In this thesis we present two studies of star-forming galaxies at z \u22482-3 based on deep spectroscopic and narrow band imaging observations. The first study addresses pressing questions regarding the nature of galaxies \r\nwith significant escaping Lyman continuum radiation. Our second study investigates the nature of spatially extended Lyman alpha emission first observed in the form of luminous Lyman alpha \"blobs.\"
\r\n\r\nIn part I of this thesis we present the results of a deep spectroscopic survey to detect Lyman continuum radiation from individual galaxies at z\u22483. Our measurements suggest that the escape fraction is strongly variable among galaxies at all luminosities, but that there is a significant preference for higher escape fraction in objects with luminosity lower than L_star. The\r\nintegrated escaping radiation from galaxies is sufficient to complement the contribution of AGN in keeping the hydrogen in the Universe ionized. Using supporting near-IR and mid-IR photometry we derive model stellar population parameters and discover that Lyman continuum is preferentially detected among objects with lowest values for dust extinction and star-formation rate. This finding may indicate a connection between Lyman continuum escape and the evolutionary stage of a galaxy.
\r\n\r\nIn part II we present deep imaging observations in a narrow band centered on Lyman \u03b1 and H \u03b1 at the redshift of a known protocluster of star-forming galaxies (z=2.3). We discover 6 new giant and bright Lyman \u03b1 \"blobs\" and identify a large number of Lyman \u03b1 and H \u03b1 emitters at the protocluster redshift. We find an anticorrelation between Lyman \u03b1 and H \u03b1 selection, which is explained by the observation that H \u03b1 emitters show Lyman \u03b1 line in absorption in their spectra. However, the composite Lyman \u03b1 narrow-band image of H \u03b1 emitters uncovers extended emission resembling Lyman \u03b1 blobs in miniature. We conclude that faint Lyman \u03b1 emission from gas within a radius of 40 kpc (or more) is likely a feature common to most galaxies at these redshifts. If ionizing photons produced in star-forming regions are responsible for this faint Lyman \u03b1 \"glow\", then this extended flux represents a significant fraction of total predicted Lyman \u03b1 equivalent width.
\r\n", "doi": "10.7907/KR0M-DH91", "publication_date": "2010", "thesis_type": "phd", "thesis_year": "2010" }, { "id": "thesis:3448", "collection": "thesis", "collection_id": "3448", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-170617", "primary_object_url": { "basename": "Thesis.pdf", "content": "final", "filesize": 1897034, "license": "other", "mime_type": "application/pdf", "url": "/3448/9/Thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "The Luminous, the Massive and the Dusty: A Near- to Mid-Infrared Spectroscopic Study of Submillimeter Galaxies", "author": [ { "family_name": "Men\u00e9ndez-Delmestre", "given_name": "Kar\u00edn", "orcid": "0000-0003-3153-5123", "clpid": "Men\u00e9ndez-Delmestre-Kar\u00edn" } ], "thesis_advisor": [ { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" } ], "thesis_committee": [ { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "clpid": "Scoville-N-Z" }, { "family_name": "Benson", "given_name": "Andrew J.", "clpid": "Benson-A-J" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Cohen", "given_name": "Judith G.", "clpid": "Cohen-J-G" }, { "family_name": "Armus", "given_name": "Lee", "clpid": "Armus-L" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Submillimeter (submm) surveys have uncovered a population of dust-enshrouded ultra-luminous galaxies that are inconspicuous in deep surveys at shorter wavelengths. Inferred to have high star-formation rates (up to more than 1000 Msun/yr), submm-selected galaxies (SMGs) contribute significantly to the global star-formation rate density at z~2-3 and are thus critical players in building up stars in galaxies. Many SMGs have been shown to display X-ray, optical and near-infrared (IR) signatures of active galactic nuclei (AGN), prompting the question: how significant is the AGN contribution to their total luminosity? Central to understanding SMGs is the study of the nature of their power source, their internal dynamics, their SFRs and their masses. We study mid-IR and near-IR spectra of SMGs to investigate these aspects.
\r\n\r\nWe have obtained the largest sample of 24 SMGs to date with the mid-IR Spitzer Infrared Spectrograph (IRS) at z ~ 0.65 - 3.2. Broad PAH emission features -- typically associated to intense star-formation -- are almost ubiquitous in the sample and the composite spectrum is well fit by a combination of a starburst component with an additional power law representing less than a 35% AGN contribution to the bolometric luminosity. We find weak silicate absorption in contrast to local ultra-luminous IR galaxies (ULIRGs), suggesting that the mid-IR visible star formation in SMGs occurs in a more extended component.
\r\n\r\nWe also study the near-IR emission of SMGs with the OH-Suppressing Infrared Imaging Spectrograph (OSIRIS), together with the Keck Laser-Guide Star Adaptive Optics system, to investigate the distribution and dynamics of the ionized gas. The two-dimensional insight of these observations allow us to distinguish and quantify the compact AGN emission, which allows us to refine estimates of dynamical masses, SFRs and gas masses for the population. With a spatially-resolved spectroscopic insight into the kpc-scale structure of these galaxies, we find that the H-alpha emission in SMGs extends over scales ~4-17 kpc, setting SMGs apart from local ULIRGs, where intense emission is confined to the central 1 kpc.
\r\n", "doi": "10.7907/J1R4-5F20", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:5212", "collection": "thesis", "collection_id": "5212", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282009-124109", "primary_object_url": { "basename": "Thesis_Hilke_Schlichting.pdf", "content": "final", "filesize": 822274, "license": "other", "mime_type": "application/pdf", "url": "/5212/1/Thesis_Hilke_Schlichting.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Understanding the Origin of Planetary Systems: Studying the Kuiper Belt and the Dynamics of Planet Formation", "author": [ { "family_name": "Schlichting", "given_name": "Hilke Elisabeth", "clpid": "Schlichting-Hilke-Elisabeth" } ], "thesis_advisor": [ { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" } ], "thesis_committee": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "clpid": "Hillenbrand-L-A" }, { "family_name": "Brown", "given_name": "Michael E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Sari", "given_name": "Re'em", "orcid": "0000-0002-1084-3656", "clpid": "Sari-R" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis presents theoretical and observational studies pertaining to the early solar system, planet formation and extrasolar planets.
\r\n\r\nFirst, we explore the dynamics of protoplanet formation. We find that the growth of protoplanets may be dominated by the accretion of a planetesimal disk that forms from planetesimal-planetesimal collisions, rather than direct planetesimal impacts onto the protoplanet. This has far reaching implications for the formation of planets, their growth rate and dynamics. We focus on the implications for planetary spins: it can explain the prevalence of prograde spins of planets and asteroids in the solar system, which is commonly believed to be an accident.
\r\n\r\nSecond, we present a series of investigations of the formation of multiple systems in the Kuiper Belt. Two of our studies are concerned with the formation of comparable mass binaries. We find that in a dynamically cold Kuiper Belt, binaries become bound predominantly by dynamical friction. This leads to a binary population with mostly retrograde mutual binary orbits. In a dynamically hot Kuiper Belt three-body gravitational interactions dominate the binary formation producing a roughly equal number of prograde and retrograde binaries. We propose a new formation scenario for Haumea\u2019s collisional family. In our scenario, the family members are ejected while in orbit around Haumea rather than directly from Haumea\u2019s surface as previously proposed. Our formation scenario offers an explanation for the observed velocity dispersion among the family members which is much smaller than Haumea\u2019s escape velocity. It is consistent with detecting just one collisional family in the Kuiper Belt and aids with explaining Haumea\u2019s initial giant impact.
\r\n\r\nWe conclude with observational work that aims to detect sub-km sized Kuiper Belt objects and to measure their size-distribution. Our results provide the best constraint on the surface density of small Kuiper Belt objects to date. Our findings support the idea that small Kuiper Belt objects underwent collisional evolution that modified their size distribution. We present our first candidate occultation event and show that it is unlikely to be due to instrumental artifacts or statistical fluctuations in the data.
", "doi": "10.7907/SGJJ-9V78", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:3182", "collection": "thesis", "collection_id": "3182", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08212007-151300", "primary_object_url": { "basename": "thesis_final.pdf", "content": "final", "filesize": 4753615, "license": "other", "mime_type": "application/pdf", "url": "/3182/1/thesis_final.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Understanding the Physical Processes Driving Galaxy Evolution in Clusters: A Case Study of Two z ~ 0.5 Galaxy Clusters", "author": [ { "family_name": "Moran", "given_name": "Sean Michael", "orcid": "0000-0002-9194-5071", "clpid": "Moran-Sean-Michael" } ], "thesis_advisor": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" } ], "thesis_committee": [ { "family_name": "Djorgovski", "given_name": "George", "clpid": "Djorgovski-G" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Blake", "given_name": "Geoffrey A.", "clpid": "Blake-G-A" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Clusters of galaxies represent the largest laboratories in the universe for testing the incredibly chaotic physics governing the collapse of baryons into the stars, galaxies, groups, and diffuse clouds that we see today. Within the cluster environment, there are a wide variety of physical processes that may be acting to transform galaxies.
\r\n\r\nIn this thesis, we combine extensive Keck spectroscopy with wide-field HST imaging to perform a detailed case study of two intermediate redshift galaxy clusters, Cl 0024+1654 (z=0.395) and MS 0451-03 (z=0.540). Leveraging a comprehensive multiwavelength data set that spans the X-ray to infrared, and with spectral-line measurements serving as the key to revealing both the recent star-formation histories and kinematics of infalling galaxies, we aim to shed light on the environmental processes that could be acting to transform galaxies in clusters.
\r\n\r\nWe adopt a strategy to make maximal use of our HST-based morphologies by splitting our sample of cluster galaxies according to morphological type, characterizing signs of recent evolution in spirals and early types separately. This approach proves to be powerful in identifying galaxies that are currently being altered by an environmental interaction: early-type galaxies that have either been newly transformed or prodded back into an active phase, and spiral galaxies where star formation is being suppressed or enhanced all stand out in our sample.
\r\n\r\nWe begin by using variations in the early-type galaxy population as indicators of recent activity. Because ellipticals and S0s form such a homogeneous class in the local universe, we are sensitive to even very subtle signatures of recent and current environmental interactions. This study has yielded two key results: By constructing the Fundamental Plane (FP) of Cl 0024, we observe that elliptical and S0 galaxies exhibit a high scatter in their FP residuals, which occurs only among galaxies in the cluster core, suggesting a turbulent assembly history for Cl 0024 early types. Near the Virial radius of Cl 0024, we observe a number of compact, intermediate-mass ellipticals undergoing a burst of star formation or weak AGN activity, indicated by strong [O II] emission; their locations may mark the minimum radius at which merging is effective in each cluster.
\r\n\r\nWhile E+S0 galaxies do prove to be sensitive indicators of environmental interaction, it is the spiral galaxies that, of course, host the bulk of star formation within and around these clusters. We therefore probe for kinematic disturbances in spiral disks by measuring resolved rotation curves from optical emission lines, and constructing the Tully-Fisher relation for spirals across Cl 0024 and MS 0451. We find that the cluster Tully-Fisher relation exhibits significantly higher scatter than the field relation. In probing for the origin of this difference, we find that the central mass densities of star-forming spirals exhibit a sharp break near the cluster Virial radius, with spirals in the cluster outskirts exhibiting significantly lower densities. We argue that these results considered together demonstrate that cluster spirals are kinematically disturbed by their environment, likely due to galaxy-galaxy interactions (harassment).
\r\n\r\nWe then discuss our most powerful method of tracking galaxy evolution across Cl 0024 and MS 0451: identifying and studying \"transition galaxies\"-galaxies whose stellar populations or dynamical states indicate a recent or ongoing change in morphology or star formation rate. Such galaxies are often revealed by star formation histories that seem to be at odds with the galaxy morphologies: for example, spiral galaxies with no signs of star formation, or elliptical galaxies that do show signs of star formation.
\r\n\r\nWe identify and study one such class of objects, the \"passive spirals\" in Cl 0024. These objects exhibit no emission lines in their spectra, suggesting a lack of star formation, yet are surprisingly detected in the UV, revealing the presence of young stars. By modeling the different temporal sensitivities of UV and spectroscopic data to recent activity, we show that star formation in Cl 0024 passive spirals has decayed on timescales of less than 1 Gyr, consistent with the action of \"gas starvation\".
\r\n\r\nWe then build on and link together our previous indications of galaxy evolution at work, aiming to piece together a more comprehensive picture of how cluster galaxies are affected by their environment at intermediate redshift. To accomplish this, we document what we believe to be the first direct evidence for the transformation of spirals into S0s: through an analysis of their stellar populations and recent star formation rates, we link the passive spiral galaxies in both clusters to their eventual end states as newly generated cluster S0 galaxies. Differences between the two clusters in both the timescales and spatial location of this conversion process allow us to evaluate the relative importance of several proposed physical mechanisms that could be responsible for the transformation. Combined with other diagnostics that are sensitive to either ICM-driven galaxy evolution or galaxy-galaxy interactions, we describe a self-consistent picture of galaxy evolution in clusters.
\r\n\r\nWe find that spiral galaxies within infalling groups have already begun a slow process of conversion into S0s primarily via gentle galaxy-galaxy interactions that act to quench star formation. The fates of spirals upon reaching the core of the cluster depend heavily on the cluster ICM, with rapid conversion of all remaining spirals into S0s via ram-pressure stripping in clusters where the ICM is dense. In the presence of a less-dense ICM, the conversion continues at a slower pace, with galaxy-galaxy interactions continuing to play a role along with \"starvation\" by the ICM. We conclude that the buildup of the local S0 population through the transformation of spiral galaxies is a heterogeneous process that nevertheless proceeds robustly across a variety of different environments from cluster outskirts to cores.
", "doi": "10.7907/C7Q1-DF25", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:2208", "collection": "thesis", "collection_id": "2208", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282008-104041", "primary_object_url": { "basename": "bjnaylor-thesis.pdf", "content": "final", "filesize": 27610308, "license": "other", "mime_type": "application/pdf", "url": "/2208/2/bjnaylor-thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Broadband Millimeter-Wave Spectroscopy with Z-Spec: An Unbiased Molecular-Line Survey of the Starburst Galaxy M82", "author": [ { "family_name": "Naylor", "given_name": "Bret Justin", "clpid": "Naylor-Bret-Justin" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Politzer", "given_name": "Hugh David", "clpid": "Politzer-H-D" }, { "family_name": "Golwala", "given_name": "Sunil", "clpid": "Golwala-S-R" }, { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Z-Spec is a broadband, millimeter-wave, direct-detection spectrometer based on a novel waveguide grating architecture. It is designed to fully cover the wide one-millimeter atmospheric window with a frequency range of 186 to 307 GHz at a resolution of ~ 250. The design goal is the detection of rotational and fine structure lines from the distant population of galaxies that make up the far-infrared background. Its large instantaneous bandwidth enables detection of multiple transitions of carbon monoxide and a relatively rapid determination of redshift. The grating design is based on the Rowland architecture but is much more compact because of the use of a parallel-plate waveguide propagation medium. Z-Spec uses 160 silicon nitride micromesh bolometers and is cooled to less than 100 mK to achieve background-limited performance. Moreover, Z-Spec serves as a technology demonstration of a technique that is uniquely suited to far-infrared extragalactic spectroscopy from space.
\r\n\r\nZ-Spec's capabilities enable wide-coverage, unbiased line surveys of nearby galaxies. Searches for molecular lines outside our own galaxy have typically been targeted at specific transitions of particular molecules. The brightest sources of extra-galactic molecular lines come from galaxies with physical conditions very different from those found in the Milky Way. Unbiased searches for spectral lines can discover transitions and molecules that are unexpected. A three-pointing study of the prototypical starburst galaxy M82 was performed with Z-Spec at the Caltech Submillimeter Observatory. The survey detected eleven bright lines in the center of the Z-Spec band, of which four had not been previously detected. Two of the new detections are for molecules that had been detected at lower frequencies (HNC 3 - 2 and C2H 3 - 2) and the other two are potentially transitions of SO2, for which only upper limits on lower frequency transitions were previously available. Several detected molecules are analyzed using a large-velocity-gradient (LVG) radiative-transfer model and indicate significant regions of high-density molecular gas along the major axis of M82.
", "doi": "10.7907/Y6TP-5E10", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:3237", "collection": "thesis", "collection_id": "3237", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08272007-043911", "primary_object_url": { "basename": "DetectionAndExploration.pdf", "content": "final", "filesize": 4999008, "license": "other", "mime_type": "application/pdf", "url": "/3237/1/DetectionAndExploration.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "The Detection and Exploration of Planets from the Trans-Atlantic Exoplanet Survey", "author": [ { "family_name": "O'Donovan", "given_name": "Francis Thomas", "orcid": "0000-0002-4858-6106", "clpid": "O'Donovan-Francis-Thomas" } ], "thesis_advisor": [ { "family_name": "Charbonneau", "given_name": "David", "clpid": "Charbonneau-D" } ], "thesis_committee": [ { "family_name": "Brown", "given_name": "Michael E.", "orcid": "0000-0002-8255-0545", "clpid": "Brown-M-E" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Charbonneau", "given_name": "David", "clpid": "Charbonneau-D" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "clpid": "Hillenbrand-L-A" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "I present the discovery of three transiting planets (TrES-2, TrES-3, and TrES-4) of nearby bright stars made with the ten-centimeter telescope Sleuth as part of the Trans-atlantic Exoplanet Survey (TrES). TrES-2 is the first transiting exoplanet detected in the field of view of NASA\u2019s Kepler mission. Of the 20 known transiting exoplanets, TrES-3 has the second shortest period, facilitating the study of orbital decay and atmospheric evaporation. Its visible/infrared brightness makes TrES-3 an ideal target for observations to determine the atmospheric composition. TrES-4 has the largest radius and lowest density of the known transiting planets. These three planets have radii larger than that of Jupiter, and the radius of TrES-4 significantly exceeds predictions from models of hot Jupiters, indicating a possible lack of an energy source in these models.
\r\n\r\nI present the results of Spitzer observations of TrES-2. I reject tidal dissipation of eccentricity as an explanation for the inflated radius, and examine the spectrum for evidence of atmospheric absorption.
\r\n\r\nI have monitored 19 fields each containing 6,000\u201336,000 stars for evidence of transits. I discuss the rejection of six of my candidate transiting systems from an early field that represent examples of the 67 astrophysical false positives that I encountered in Sleuth data. These six false positives highlight the benefit of a multisite survey such as TrES, and also of comprehensive follow-up of transit candidates. As a further example, I present the candidate GSC 03885-00829 from Sleuth data that was revealed to be a blend of a bright F dwarf and a fainter K-dwarf eclipsing binary. This candidate proved nontrivial to reject, requiring multicolor follow-up photometry to produce evidence of the true binary nature of this candidate.
\r\n\r\nThe yield of planets from transit surveys is not yet well constrained or understood. There are numerous factors that affect the predictions such as the amount of correlated photometric noise present in the data. Here I present an analysis of my ability to recover fake transits in TrES data. I examined both the automated transit-search algorithm and my own visual identification process. I find the recovery rate of my visual analysis to be 87% for those transit candidates that had a sufficiently high signal-to-noise ratio to be flagged by my transit-search algorithm and readily identifiable by eye.
", "doi": "10.7907/585M-JF91", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:324", "collection": "thesis", "collection_id": "324", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01242008-093655", "primary_object_url": { "basename": "final_thesis_version_jan24.pdf", "content": "final", "filesize": 4390861, "license": "other", "mime_type": "application/pdf", "url": "/324/1/final_thesis_version_jan24.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Multi-Wavelength Properties of Submillimeter-Selected Galaxies", "author": [ { "family_name": "Hainline", "given_name": "Laura Jeannine", "clpid": "Hainline-Laura-Jeannine" } ], "thesis_advisor": [ { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" } ], "thesis_committee": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "clpid": "Scoville-N-Z" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The resolution of the cosmic far-infrared background at long wavelengths has uncovered a population of high-redshift, highly infrared-luminous galaxies that indicate that a significant amount of highly obscured star formation occurred in the early history of the Universe, which has not been taken into account in studies of the cosmic star formation and mass assembly histories. Since such studies are important tests of hierarchical galaxy formation models in a cold dark matter- dominated universe, it is vital that the contribution of these luminous submillimeter-selected galaxies to the buildup of stellar mass in the Universe be understood and included when testing galaxy formation models. Progress in understanding the nature of submillimeter-selected galaxies has been slow, however, due to the faintness of the population outside of the submillimeter bands and the coarse resolution of the single-dish submillimeter surveys in which the galaxies were discovered. The slow progress has at least two important consequences: (1) there is still much that is unknown about submillimeterselected galaxies at all wavelengths, so the properties of and evolutionary predictions for the population are often inferred by making analogies to local galaxies of similar luminosity and assuming the high-redshift galaxies represent a uniform population of galaxies; and (2) the relationships of the submillimeter-selected galaxies to other high-redshift galaxy populations selected at other wavelengths remain poorly understood.
\r\n\r\nIn this work we capitalize on recently-available observing resources of the Spitzer Space Telescope, at near- and mid-infrared wavelengths, and the Green Bank Telescope, at 1 cm, to improve the characterization of the largest representative sample of submillimeter-selected galaxies with spectroscopic redshifts. We combine our new data with data from the literature at a variety of wavelengths to place new constraints on the fundamental properties of gas mass, stellar mass, infrared luminosity, and spectral energy distribution, and use our new constraints to test a variety of assumptions which have been used in the past to predict and infer characteristics of submillimeter-selected galaxies. We also use our new data to compare different populations of high-redshift galaxies selected at different wavelengths in an effort to understand the relationships between the different types of galaxies.
\r\n\r\nFirst, we use observations of CO rotational line emission with the Green Bank Telescope to constrain the cold gas mass and gas conditions in several submillimeter-selected galaxies. We obtain the first detection of CO(1\u21920) emission from a submillimeter-selected galaxy, finding that the CO(4\u21923)/CO(1\u21920) brightness temperature ratio of ~ 0.26 suggests n(H\u2082) > 3 \u2212 10 \u00d7 10\u00b2 cm\u207b\u00b3 and the presence of sub-thermally excited gas. The integrated line flux implies a cold molecular gas mass 4 times larger than the mass predicted from the CO(4\u21923) line, assuming a brightness temperature ratio of 1.0, suggesting that extrapolating molecular gas masses from J upper \u2265 3 transitions of CO, which is the primary method of estimating molecular gas masses of high-z galaxies in the literature, leads to considerable uncertainties.
\r\n\r\nNext, we use deep imaging with the Multiband Imaging Photometer for Spitzer (MIPS) on the Spitzer Space Telescope of the spectroscopic sample of radio-detected submillimeter-selected galaxies of Chapman et al. (2005) to derive new estimates of the infrared luminosity for these objects. Our Spitzer data constrain the Wien side of the infrared spectral energy distribution peak of high-redshift submillimeter-selected galaxies, and thus are extremely important to determine the contribution of hot dust emission to the total infrared luminosity. We find that most submillimeter-selected galaxies do not have dominant contributions from hot dust at rest-frame mid-infrared wavelengths. We also find that the spectral energy distribution of the nearest ultraluminous infrared galaxy, Arp 220, is significantly different on average from most high-z submillimeter-selected galaxies and is thus a poor template with which to predict properties of submillimeter-selected galaxies even though it has been often used in the past. Using our new infrared luminosity estimates constrained by multiple infrared and submillimeter data points, we show that submillimeter-selected galaxies display a relatively tight, almost linear correlation between total infrared luminosity and radio luminosity, which is not largely different from the far-infrared\u2013radio correlation of local galaxies selected by the Infrared Astronomical Satellite (IRAS).
\r\n\r\nWe examine the rest-frame ultraviolet through near-infrared spectral energy distributions of the same sample of radio-detected submillimeter-selected galaxies with spectroscopic redshifts, obtained using measurements from imaging with the Infrared Array Camera (IRAC) on Spitzer in combination with observed-frame optical and near-infrared data from the literature. We find from these spectral energy distributions, which trace the stellar light from a galaxy in the absence of an active nucleus, that submillimeter-selected galaxies suffer significant extinction at rest-frame optical wavelengths, and that both stars and dust emission contribute to the near-infrared luminosity in many z > 2 submillimeter-selected galaxies. We estimate stellar masses for the individual galaxies in the sample using restframe H-band luminosities interpolated from the observed spectral energy distributions, obtaining a median stellar mass for the sample of 6 \u2212 7 \u00d7 10\u00b9\u2070 Msun. By comparing our stellar mass estimates to molecular gas and dynamical mass estimates for 13 individual submillimeter-selected galaxies in our sample observed in CO emission lines, we determine that the molecular gas fraction in submillimeter-selected galaxies declines with increasing stellar mass, which is suggestive of an evolutionary trend. If the molecular gas masses for the 13 galaxies for which gas mass estimates are available are typical of the entire radiodetected submillimeter-selected galaxy population, then a typical lower limit to the total baryonic mass of submillimeter-selected galaxies is ~ 10\u00b9\u00b9 Msun, and these galaxies are unlikely to significantly increase their stellar mass in the current epoch of activity which is the source of their enormous infrared luminosity.
\r\n\r\nLastly, we compare the IRAC and MIPS properties of submillimeter-selected galaxies and their stellar masses to those of high-redshift ultraviolet- and optically-selected galaxies, 24 \u03bcm-selected galaxies, and powerful radio galaxies. In the IRAC bands, submillimeter-selected galaxies are brighter and redder than ultraviolet-selected galaxies, suggesting they have higher dust content, higher stellar mass, a higher contribution from an active nucleus, or some combination of these factors. The near-infrared colors of submillimeterselected galaxies are most similar to those of high-z radio galaxies, objects which are known to contain powerful, obscured active nuclei. However, submillimeter-selected galaxies are fainter in the MIPS 24 \u03bcm band than high-z radio galaxies, suggesting that the dust in the submillimeter-selected galaxies is not heated to such high temperatures as in the radio sources. We find that the typical stellar mass of submillimeter-selected galaxies is larger by a factor of 3\u20134 than that of high-redshift ultraviolet-selected galaxies, roughly similar to the typical stellar mass of optically-selected high-z galaxies, and lower than the typical stellar mass of powerful high-z radio galaxies. These comparisons suggest that submillimeter-selected galaxies are among the more massive galaxies of their epoch, but not necessarily the most massive, as has been suggested in the literature. However, systematic errors in the stellar masses of any of the high-redshift galaxy samples of a factor of a few, which are certainly possible, can alter this conclusion.
", "doi": "10.7907/Q4DB-K461", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:5243", "collection": "thesis", "collection_id": "5243", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08012006-120712", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 4705947, "license": "other", "mime_type": "application/pdf", "url": "/5243/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Submillimeter Surveys of Galaxy Samples", "author": [ { "family_name": "Yang", "given_name": "Min", "clpid": "Yang-Min" } ], "thesis_advisor": [ { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" } ], "thesis_committee": [ { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Soifer", "given_name": "B. Thomas", "clpid": "Soifer-B-T" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis aims to gain a better understanding of dusty galaxies by studying the thermal emission of interstellar dust at submillimeter (submm) wavelengths. We conduct 350\u03bcm observations of two galaxy samples selected based on entirely different criteria, using the Submillimeter High Angular Resolution Camera II (SHARC-II, Dowell et al. 2003) at the 10.4m Caltech Submillimeter Observatory (CSO).
\r\n\r\nThe first galaxy sample consists of 18 luminous infrared galaxies (LIGs) in the local Universe (0.003 \u2264 z \u2264 0.042). We estimate the global properties in this galaxy sample; dust temperature (Td = 38.6 \u00b1 7.7 K), emissivity index (\u03b2 = 1.6 \u00b1 0.3), far-infrared (FIR) luminosity (Lfir = 1011.2\u00b10.6 L\u2609}) and dust mass (Md = 107.4\u00b10.6 M\u2609). Guided by theoretical considerations and laboratory measurements, we derive a Td-\u03b2 inverse correlation for the local LIG sample; Td = [5.03 x 109]1/4.46 + \u03b2.
\r\n\r\nThe second galaxy sample consists of 36 ultraluminous infrared galaxies (ULIGs) at moderate redshifts (0.1 < z < 1.0), out of which 28 galaxies are detected. The newly acquired 350\u03bcm data, in combination with the pre-existing IRAS 60\u03bcm and 100\u03bcm data, leads to meaningful estimates of the global properties in these galaxies for the first time; Td = 40.9 \u00b1 6.9K, Lfir = 1012.2\u00b10.5 L\u2609, Md = 108.3\u00b10.3 M\u2609 and intense starburst activity (SFR = 102.5\u00b10.5 L\u2609 yr-1). There is strong circumstantial evidence that the Td-\u03b2 inverse correlation observed in the local LIG sample remains valid in ULIGs at moderate redshifts. We find that the FIR-radio correlation observed in local star-forming galaxies continues to hold for ULIGs over the redshift range of 0.1 < z < 1.0 and dust heating originates predominantly from star formation. Lfir and Td derived for dusty galaxy samples over a wide range of redshifts show significant scatter, due to differing selection biases and variations in dust mass and grain properties. We argue that the observed Td, as a large-scale SED parameter, is linked to the global star formation efficiency (SFE) and the spatial extent characteristic of dominant star formation in a galaxy.
", "doi": "10.7907/ZTAY-AM05", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:22", "collection": "thesis", "collection_id": "22", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01042006-100808", "primary_object_url": { "basename": "main.pdf", "content": "final", "filesize": 6347393, "license": "other", "mime_type": "application/pdf", "url": "/22/1/main.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "On the Distribution of Dark Matter in Clusters of Galaxies", "author": [ { "family_name": "Sand", "given_name": "David Jerome", "orcid": "0000-0003-4102-380X", "clpid": "Sand-David-Jerome" } ], "thesis_advisor": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" } ], "thesis_committee": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Mulchaey", "given_name": "John S.", "clpid": "Mulchaey-J-S" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The goal of this thesis is to provide constraints on the dark matter density profile in galaxy clusters by developing and combining different techniques. The work is motivated by the fact that a precise measurement of the logarithmic slope of the dark matter on small scales provides a powerful test of the Cold Dark Matter paradigm for structure formation, where numerical simulations suggest a density profile [see PDF] or steeper in the innermost regions.
\r\n\r\nWe have obtained deep spectroscopy of gravitational arcs and the dominant brightest cluster galaxy in six carefully chosen galaxy clusters. Three of the clusters have both radial and tangential gravitational arcs while the other three display only tangential arcs. We analyze the stellar velocity dispersion for the brightest cluster galaxies in conjunction with axially symmetric lens models to jointly constrain the dark and baryonic mass profiles jointly. For the radial arc systems we find the inner dark matter density profile is consistent with [see PDF], with [see PDF] (68% CL). Likewise, an upper limit on [see PDF] for the tangential arc sample is found to be [see PDF]0.57 (99% CL). We study a variety of possible systematic uncertainties, including the consequences of our one-dimensional mass model, fixed dark matter scale radius, and simple velocity dispersion analysis, and conclude that at most these systematics each contribute a $Delta \\beta sim 0.2$ systematic into our final conclusions. These results suggest the relationship between dark and baryonic matter in cluster cores is more complex than anticipated from dark matter only simulations.
\r\n\r\nRecognizing the power of our technique, we have performed a systematic search of the Hubble Space Telescope Wide Field and Planetary Camera 2 data archive for further examples of systems containing tangential and radial gravitational arcs. We carefully examined 128 galaxy cluster cores and found 104 tangential arcs and 12 candidate radial arcs, each of whose length to width ratio exceeds 7. Twenty-four additional radial arc candidates were identified with smaller length to width ratios. In order to confirm the nature of these radial arc candidates, we obtained Keck spectroscopy of 17 candidate radial arcs, suggesting that the contamination rate from non-lensed objects is ~30-50%. With this catalog of gravitational arcs, we use the number ratio of radial to tangential arcs as a statistical measure of the inner logarithmic dark matter slope, [see PDF], in galaxy cluster cores. This abundance ratio is fairly constant across various cluster subsamples partitioned according to X-ray luminosity and optical survey depth. Using two-component mass models for cluster cores, we show that the arc statistics in our survey are consistent with [see PDF] 1.6, depending on various assumptions, the most important of which is the stellar mass associated with the brightest cluster galaxy.
\r\n\r\nFinally, in order to refine and confirm the analysis technique presented for the six galaxy clusters with gravitational arcs and brightest cluster galaxy dynamics, and to address several comments on our earlier work, we present a more elaborate two dimensional lens model of the cluster MS2137 using a newly upgraded gravitational lensing code. We combine these two-dimensional lens model constraints with the velocity dispersion data of the brightest cluster galaxy to constrain the dark and baryonic mass profiles jointly. We find the inner dark matter density profile to be consistent with a distribution with logarithmic inner slope [see PDF] (68% CL) in agreement with the axially symmetric model presented earlier for MS2137 ([see PDF]) with simpler assumptions. However, we do find a significant degeneracy remains between the scale radius, [see PDF], and inner logarithmic slope, [see PDF], which might be resolved with further lensing data at larger radii. Notwithstanding this limitation, we conclude that our technique of combining gravitational lensing with stellar dynamics offers a reliable probe of the dark matter distribution in clusters and that, most likely, a discrepancy remains between numerical predictions in the CDM paradigm and our observations.
", "doi": "10.7907/E5WC-Q847", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:3229", "collection": "thesis", "collection_id": "3229", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08262005-170055", "primary_object_url": { "basename": "Metchev_Thesis.pdf", "content": "final", "filesize": 8334006, "license": "other", "mime_type": "application/pdf", "url": "/3229/1/Metchev_Thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Brown Dwarf Companions to Young Solar Analogs: An Adaptive Optics Survey Using Palomar and Keck", "author": [ { "family_name": "Metchev", "given_name": "Stanimir Angelov", "orcid": "0000-0003-3050-8203", "clpid": "Metchev-Stanimir-Angelov" } ], "thesis_advisor": [ { "family_name": "Hillenbrand", "given_name": "Lynne A.", "clpid": "Hillenbrand-L-A" } ], "thesis_committee": [ { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Stevenson", "given_name": "David John", "orcid": "0000-0001-9432-7159", "clpid": "Stevenson-D-J" }, { "family_name": "Hillenbrand", "given_name": "Lynne A.", "clpid": "Hillenbrand-L-A" }, { "family_name": "Dekany", "given_name": "Richard G.", "clpid": "Dekany-R-G" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present results from an adaptive optics survey conducted with the Palomar and Keck telescopes over 3 years, which measured the frequency of stellar and sub-stellar companions to Sun-like stars. The survey sample contains 266 stars in the 3-10000 million year age range at heliocentric distances between 8 and 200 parsecs and with spectral types between F5-K5. A sub-sample of 101 stars, between 3-500 million years old, were observed in deep exposures with a coronagraph to search for faint sub-stellar companions. A total of 288 candidate companions were discovered around the sample stars, which were re-imaged at subsequent epochs to determine physical association with the candidate host stars by checking for common proper motion. Benefiting from a highly accurate astrometric calibration of the observations, we were able to successfully apply the common proper motion test in the majority of the cases, including stars with proper motions as small as 20 milli-arcseconds/year.
\r\n\r\nThe results from the survey include the discovery of three new brown dwarf companions (HD 49197B, HD 203030B, and ScoPMS 214B), 43 new stellar binaries, and a triple system. The physical association of an additional, a priori-suspected, candidate sub-stellar companion to the star HII 1348 is astrometrically confirmed. The newly-discovered and confirmed young brown dwarf companions span a range of spectral types between M5 and T0.5, and will be of prime significance for constraining evolutionary models of young brown dwarfs and extra-solar planets.
\r\n\r\nBased on the 3 new detections of sub-stellar companions in the 101 star sub-sample and following a careful estimate of the survey incompleteness, a Bayesian statistical analysis shows that the frequency of 0.012-0.072 solar-mass brown dwarfs in 30-1600 AU orbits around young solar analogs is 6.8% (-4.9%, +8.3\\%; 2-sigma limits). While this is a factor of 3 lower than the frequency of stellar companions to G-dwarfs in the same orbital range, it is significantly higher than the frequency of brown dwarfs in 0-3 AU orbits discovered through precision radial velocity surveys. It is also fully consistent with the observed frequency of 0-3 AU extra-solar planets. Thus, the result demonstrates that the radial-velocity \"brown dwarf desert\" does not extend to wide separations, contrary to previous belief.
", "doi": "10.7907/ZGB1-CY59", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:3380", "collection": "thesis", "collection_id": "3380", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09082005-113029", "primary_object_url": { "basename": "main.pdf", "content": "final", "filesize": 14019184, "license": "other", "mime_type": "application/pdf", "url": "/3380/1/main.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "The Properties of Star-Forming Galaxies at z ~ 2: Kinematics, Stellar Populations, and Metallicities", "author": [ { "family_name": "Erb", "given_name": "Dawn Karuna", "orcid": "0000-0001-9714-2758", "clpid": "Erb-Dawn-Karuna" } ], "thesis_advisor": [ { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" } ], "thesis_committee": [ { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Sargent", "given_name": "Anneila Isabel", "clpid": "Sargent-A-I" }, { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We study the properties of star-forming galaxies at redshift z ~ 2, an era in which a substantial fraction of the stellar mass in the universe formed. Using 114 near-IR spectra of the H\u03b1 and [N II] emission lines and model spectral energy distributions fit to rest-frame UV through IR photometry, we examine the galaxies' star formation properties, dynamical masses and velocity dispersions, spatially resolved kinematics, outflow properties, and metallicities as a function of stellar mass and age. While the stellar masses of the galaxies in our sample vary by a factor of ~ 500, dynamical masses from H\u03b1 velocity dispersions and indirect estimates of gas masses imply that the variation of stellar mass is due as much to the evolution of the stellar population and the conversion of gas into stars as to intrinsic differences in the total masses of the galaxies. About 10% of the galaxies are apparently young starbursts with high gas fractions, caught just as they have begun to convert large amounts of gas into stars. Using the [N II]/H\u03b1 ratio of composite spectra to estimate the average oxygen abundance, we find a monotonic increase in metallicity with stellar mass. From the estimated gas fractions, we conclude that the increase in metallicity as gas is converted to stars is more likely to explain the observed mass-metallicity relation than the loss of metals through outflows. The picture that emerges is of galaxies with a broad range in stellar population properties, from young galaxies with ages of a few tens of Myr, stellar masses M* ~ 10\u2079 M\u2299, and metallicities Z ~ 1/3 Z\u2299, to massive objects with M* ~ 10\u00b9\u00b9 M\u2299, Z ~ Z\u2299, and ages as old as the universe allows. All, however, are rapidly star-forming, power galactic-scale outflows, and have masses in gas and stars of at least ~ 10\u00b9\u2070 M\u2299, in keeping with their likely role as the progenitors of elliptical galaxies seen today.
", "doi": "10.7907/C5D0-7789", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:1846", "collection": "thesis", "collection_id": "1846", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05172006-133633", "primary_object_url": { "basename": "nar_thesis.pdf", "content": "final", "filesize": 4726628, "license": "other", "mime_type": "application/pdf", "url": "/1846/1/nar_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A Multi-Wavelength Census of Star Formation at Redshift z ~ 2", "author": [ { "family_name": "Reddy", "given_name": "Naveen Ananta", "orcid": "0000-0001-9687-4973", "clpid": "Reddy-Naveen-Ananta" } ], "thesis_advisor": [ { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" } ], "thesis_committee": [ { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "clpid": "Scoville-N-Z" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We examine the census of star-forming galaxies and their extinction properties at redshift z ~ 2, when a large fraction of the stellar mass in the universe formed. We find a good agreement between the X-ray, radio, and de-reddened UV estimates of the average star formation rate (SFR) for our sample of z ~ 2 galaxies of ~ 50 M\u2299 yr\u207b\u00b9, indicating that the locally calibrated SFR relations appear to be statistically valid from redshifts 1.5 \u227e z \u227e 3.0. Spitzer MIPS data are used to assess the extinction properties of individual star-forming galaxies, and we find that the rest-frame UV slope of most galaxies at z ~ 2 can be used to infer their attenuation factors, Lbol/LUV. As in the local universe, the obscuration, LFIR/LUV is strongly dependent on bolometric luminosity, and ranges in value from < 1 to ~ 1000 within the sample considered. However, the obscuration is ~ 10 times smaller at a given Lbol (or, equivalently, a similar level of obscuration occurs at luminosities ~ 10 times larger) at z ~ 2 than at z ~ 0. This trend is expected as galaxies age and their gas becomes more dust-enriched. Specific SFRs indicate wide range in the evolutionary state of galaxies at z ~ 2, from galaxies that have just begun to form stars to those that have already accumulated most of their stellar mass and are about to become, or already are, passively evolving. Finally, we examine two techniques for assessing the census of galaxies at z ~ 2. In the first, we select galaxies using optical, near-IR, and sub-mm criteria, and find a large overlap between optical and near-IR selected samples of galaxies at z ~ 2. The second technique involves reconstructing the luminosity function of z ~ 2 galaxies as determined from Monte Carlo simulations. We find that the SFR density increases between z = 4 to 2 by a factor of ~ 1.2. However, this increase is mild compared to the much steeper increase from z ~ 6 to z ~ 4, suggesting that the processes responsible for the increase in SFR density at early epochs saturate around z ~ 2.
", "doi": "10.7907/9FXD-QX54", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:2400", "collection": "thesis", "collection_id": "2400", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06022006-123747", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 1882028, "license": "other", "mime_type": "application/pdf", "url": "/2400/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "SHARC-2 350 Micron Observations of Distant Submillimeter Selected Galaxies and Techniques for the Optimal Analysis and Observing of Weak Signals", "author": [ { "family_name": "Kov\u00e1cs", "given_name": "Attila", "clpid": "Kov\u00e1cs-Attila" } ], "thesis_advisor": [ { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" } ], "thesis_committee": [ { "family_name": "Phillips", "given_name": "Thomas G.", "clpid": "Phillips-T-G" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "New 350 micron data constrain accurately the thermal far-infrared spectral energy distributions (SEDs) for 12 distant submillimeter selected galaxies (SMGs). The results confirm that the linear radio to far-infrared correlation, established for local infrared galaxies, holds out to high redshifts z ~ 1--3. The low correlation constant q ~ 2.14 is more indicative of star formation than AGN-fueled dust heating. The sample exhibits an apparent luminosity--temperature relation (L_FIR ~ T_d^2.89), possibly owing to selection effects. As a result, photometric redshifts in the radio or far-infrared may not be viable, but expressions may relate the observed quantities for current flux and volume limited SMG samples. These suggest that SED estimation may be possible, for objects similarly selected, based on a single radio or far-infrared flux measurement.
\r\n\r\nThe detection of these faint objects (~10 mJy at 350 micron) from the ground is complicated by a bright (~1000 Jy) and highly variable (~10 Jy RMS in 10 minutes of integration) atmosphere with a 1/f^2 noise spectrum and by instrumental 1/f noise. To reach optimum sensitivities, a careful analysis of the data is required, and well-chosen observing strategies are helpful. The principal techniques that aid the extraction of weak signals from colored noise are presented. Close to optimal analysis is implemented effectively by the CRUSH software. Both the computing and storage requirement of the implementation scales linearly with the size of the data set, making this approach superior to the computationally expensive alternatives for handling the very large data volumes expected from future instruments.
", "doi": "10.7907/8ZM9-6671", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:2391", "collection": "thesis", "collection_id": "2391", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06022005-151603", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2980205, "license": "other", "mime_type": "application/pdf", "url": "/2391/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "I. Ash Injection and Exposure During Radius Expansion Type I X-Ray Bursts. II. Stellar Dynamics at the Galactic Center. III. Weak Gravitational Lensing by Dark Matter Concentrations", "author": [ { "family_name": "Weinberg", "given_name": "Nevin Nachum", "orcid": "0000-0001-9194-2084", "clpid": "Weinberg-Nevin-Nachum" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" } ], "thesis_committee": [ { "family_name": "Sari", "given_name": "Re'em", "clpid": "Sari-R" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "clpid": "Kulkarni-S-R" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "The studies presented herein are on three distinct topics in astrophysics:
\r\n\r\nI. We solve for the evolution of the vertical extent of the convective region of a neutron star atmosphere during a type I X-ray burst. The convective region is well-mixed with ashes of nuclear burning, and its extent determines the burst rise time. We show that the maximum extent of the convective region during photospheric radius expansion (PRE) bursts can be sufficiently great that some ashes of burning are: (1) ejected by the radiation-driven wind during the PRE phase and, (2) exposed at the neutron star surface following the PRE phase. We calculate the expected column density of ashes in hydrogen-like states and find that the resulting photoionization edges should be detectable with current high spectral resolution X-ray telescopes. A detection would probe the burst nuclear burning processes and might enable a measurement of the neutron star gravitational redshift.
\r\n\r\nII. We discuss physical experiments achievable via the monitoring of stellar dynamics near the massive black hole (MBH) at the Galactic center with a next-generation, extremely large telescope (ELT). We use the Markov Chain Monte Carlo method to evaluate the constraints that the monitoring of these orbits will place on the matter content at the Galactic center. We compare these future constraints with those obtained with the current data. We also describe how the monitoring of stellar proper motions can be used to probe directly the masses of isolated stellar remnants near the MBH.
\r\n\r\nIII. We calculate the abundance of dark-matter concentrations that are sufficiently overdense to produce a detectable weak-gravitational-lensing signal. Most of these overdensities are virialized halos containing identifiable X-ray and/or optical clusters. However, a significant fraction are nonvirialized, cluster-mass overdensities still in the process of gravitational collapse---these should produce significantly weaker or no X-ray emission. Our predicted abundance of such dark clusters is consistent with the abundance implied by the detection of apparent dark lenses. We also examine the prospect of using weak gravitational lenses to constrain the dark energy equation-of-state parameter.
\r\n", "doi": "10.7907/V8PX-AE66", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:1677", "collection": "thesis", "collection_id": "1677", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05082004-134233", "primary_object_url": { "basename": "simcoe_dissertation.pdf", "content": "final", "filesize": 4534686, "license": "other", "mime_type": "application/pdf", "url": "/1677/1/simcoe_dissertation.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Observations of Intergalactic Heavy-Element Enrichment in the Early Universe", "author": [ { "family_name": "Simcoe", "given_name": "Robert Andrew", "clpid": "Simcoe-Robert-Andrew" } ], "thesis_advisor": [ { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "thesis_committee": [ { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Phinney", "given_name": "E. Sterl", "clpid": "Phinney-E-S" }, { "family_name": "Rauch", "given_name": "Michael", "clpid": "Rauch-M" }, { "family_name": "Djorgovski", "given_name": "George", "clpid": "Djorgovski-G" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present the results of a search for OVI absorption in the intergalactic medium (IGM) at 2 \u227e z \u227e 3. The measurements are taken from a set of 7 quasars observed with Keck I/HIRES. We find two classes of OVI system in the high redshift IGM. The first class is more rare (2-4 per sightline) and also quite strong (NH1\u22651015.2). These systems resemble hot, collisionally ionized gas at high densities, and contain complex mixtures of HI and metals at a range of temperatures. Although we cannot measure the metallicities of individual strong absorbers, we estimate that the total population is enriched over 10 times above the level of the general IGM. We propose that the strong systems represent either accretion-shocked gas falling onto primitive large-scale structure, or (more likely) the remnants of high redshift galactic winds mixing into the IGM.
\r\n\r\nThe second class of OVI absorber is much weaker, arising in low-density gas that is photoionized by metagalactic UV/X-ray radiation. We measure the metal content of these systems, down to densities of \u03c1/\u03c1\u0305 \u2265 1.6 relative to the cosmic mean. This corresponds to the filaments of the cosmic web, which contain over half of the baryons in the high redshift universe. We develop a new method to calculate the metallicity distribution function of the Ly-\u03b1 forest using survival statistics. Carbon and oxygen are both distributed lognormally, with mean\u3008[O/H]\u3009\u2248 -2.85 and scatter of \u03c3 = 0.75 dex. We observe no decline in metallicity toward lower densities, indicating that metals are mixed very efficiently within the filaments. Comparison with Population III and galactic wind enrichment models suggests that the enrichment was dominated by superwinds. We estimate that roughly half of all baryons in the IGM came into contact with metal-rich winds by z ~ 2.5. Using a \"closed box\" model of intergalactic enrichment, we estimate that early galaxies typically recycled 0.1-0.4% of their mass back into the IGM as heavy elements prior to this epoch.
", "doi": "10.7907/E1N9-BF97", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:1771", "collection": "thesis", "collection_id": "1771", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05132004-184937", "primary_object_url": { "basename": "psu_thesis.pdf", "content": "final", "filesize": 4115387, "license": "other", "mime_type": "application/pdf", "url": "/1771/1/psu_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "H\u2080 from Cosmic Background Imager Observations of the Sunyaev-Zel\u2019dovich Effect in Nearby Clusters.", "author": [ { "family_name": "Udomprasert", "given_name": "Patricia Simcoe", "clpid": "Udomprasert-Patricia-Simcoe" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-G" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present H\u2080 results from Cosmic Background Imager (CBI) observations of the Sunyaev-Zeldovich Effect (SZE) in 7 galaxy clusters, A85, A399, A401, A478, A754, A1651, and A2597. These observations are part of a program to study a complete, volume-limited sample of low-redshift (z < 0.1), X-ray selected clusters. Our focus on nearby objects allows us to study a well-defined, orientation unbiased sample, minimizing systematic errors due to cluster asphericity. We use density models derived from ROSAT imaging data and temperature measurements from ASCA and BeppoSAX spectral observations. We quantify in detail sources of error in our derivation of H\u2080, including calibration of the CBI data, density and temperature models from the X-ray data, Cosmic Microwave Background (CMB) primary anisotropy fluctuations, and residuals from radio point source subtraction. From these 7 clusters we obtain a result of Ho = 67+30-18(ran)+15-6(sys) km/s-1 Mpc-1 for an unweighted sample average. The respective quoted errors are random and systematic uncertainties at 68% confidence. The dominant source of error is confusion from intrinsic anisotropy fluctuations. We present results from simulations of an eigenmode weighting analysis that reduce the uncertainties due to CMB in h-1/2 by ~30%.", "doi": "10.7907/VR2Z-MP09", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:1855", "collection": "thesis", "collection_id": "1855", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05182004-154315", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2798490, "license": "other", "mime_type": "application/pdf", "url": "/1855/1/thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Galaxy Formation Near the Epoch of Reionization", "author": [ { "family_name": "Santos", "given_name": "Michael Robert", "clpid": "Santos-Michael-Robert" } ], "thesis_advisor": [ { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" } ], "thesis_committee": [ { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "clpid": "Kamionkowski-M-P" }, { "family_name": "Ellis", "given_name": "Richard S.", "clpid": "Ellis-R-S" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "I present five explorations of the formation of early galaxies near the epoch of reionization: observable phenomena that demonstrate the interaction between galaxy formation and the intergalactic medium.
\r\n\r\nI calculated the contribution of the first stars (Pop III) to the cosmic infrared background (CIRB). Pop III stars produced the observed unexplained component of the NIR CIRB if they were very massive and formed efficiently over a redshift range 25 \u2273 z \u2273 7. A small escape fraction of ionizing photons from the nebular gas immediately surrounding the Pop III stars enhances the Pop III CIRB signal.
\r\n\r\nI calculated the effect of radiative transfer through the intergalactic medium (IGM) on the observed properties of Lyman alpha emission lines from z \u2273 6 galaxies. The detection of a Lyman alpha emitting galaxy at z = 6.5 resulted in claims that the universe was mostly ionized there. With existing information about the source galaxy it is almost impossible to deduce the ionization state of the z = 6.5 IGM, especially if there were galactic-scale super-winds.
\r\n\r\nI present a method to infer the stellar population responsible for completing reionization. We simulated helium and hydrogen absorption along lines-of-sight toward high-redshift QSOs assuming either Pop II or Pop III stars dominated the UV background at z=5. The final SDSS quasar sample may contain a quasar/line-of-sight combination that constrains the nature of the dominant ionizing sources only 300 Myr after the end of reionization.
\r\n\r\nI present an observational survey of low-luminosity Lyman alpha emitting galaxies at 4.5 < z < 6.7. This unprecedented survey utilized strong lensing by rich clusters of galaxies at intermediate redshifts to discover six likely Lyman alpha emitting galaxies. The z ~ 5 Lyman alpha luminosity function may be flatter than the mass function of dark matter halos, a sign of suppression of the star-formation efficiency in low-mass halos. However, our data by themselves are consistent with the slope of the halo mass function.
\r\n\r\nI modeled the formation of metal-poor globular cluster systems (GCSs), invoking reionization to explain the bimodality observed in GCS metallicity distributions. The model reproduces the mass and spatial extent of the Milky Way metal-poor GCS, and also the increasing number of metal-poor globular clusters per unit galaxy mass for galaxies in richer environments, as observed.
", "doi": "10.7907/X9XT-YT35", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:1746", "collection": "thesis", "collection_id": "1746", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05122004-113008", "primary_object_url": { "basename": "hunt_thesis.pdf", "content": "final", "filesize": 1280282, "license": "other", "mime_type": "application/pdf", "url": "/1746/1/hunt_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Faint Optically Selected AGN at z = 3", "author": [ { "family_name": "Hunt", "given_name": "Matthew Philip", "orcid": "0000-0001-6920-5563", "clpid": "Hunt-Matthew-Philip" } ], "thesis_advisor": [ { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" } ], "thesis_committee": [ { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Steidel", "given_name": "Charles C.", "clpid": "Steidel-C-C" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "clpid": "Scoville-N-Z" }, { "family_name": "Phinney", "given_name": "E. Sterl", "clpid": "Phinney-E-S" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present the results of two surveys for z \u2248 3 AGN, the Lyman break galaxy (LBG) survey and a new survey based on the same techniques, but over a wider area. These surveys, spanning more than 2 deg\u00b2, yield 24 new QSOs, and 17 new narrow-lined AGN. The combined data from these surveys span a range of luminosity that is unprecedented at high redshift, covering 6.5 mag of the faint end of the QSO luminosity function. We find a substantially flatter faint-end slope at high redshift than in the local universe, \u03b2l=1.20, which has important implications for the study of supermassive black hole (SMBH) accretion and galaxy formation, as well as the state of the IGM at z \u2248 3. We also present estimates of the QSO lifetime (~ 10\u2077 yr) and compare our AGN sample with those obtained by deep X-ray imaging. We also present a guide to the reduction of imaging data from the Large Format Camera (LFC) on the Hale Telescope.", "doi": "10.7907/J5MJ-AP67", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" } ]