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Type of Document	Dissertation
Author	Menendez-Delmestre, Karin
URN	etd-09102008-170617
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-09102008-170617
Title	The luminous, the massive and the dusty: a near- to mid-infrared spectroscopic study of submillimeter galaxies
Degree	PhD
Option	Astronomy
Advisory Committee	Advisor Name Title Nick Z. Scoville Committee Chair Andrew Benson Committee Member Andrew W. Blain Committee Member Judy L. Cohen Committee Member Lee Armus Committee Member
Keywords	submillimeter galaxies Spitzer IRS Keck OSIRIS Keck NIRSPEC high-redshift galaxies
Date of Defense	2008-08-26
Availability	unrestricted
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. We 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. We 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.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    Chapter1.pdf 285.75 Kb 00:01:19 00:00:40 00:00:35 00:00:17 00:00:01   Chapter2.pdf 190.21 Kb 00:00:52 00:00:27 00:00:23 00:00:11 00:00:01   Chapter3.pdf 748.59 Kb 00:03:27 00:01:46 00:01:33 00:00:46 00:00:03   Chapter4.pdf 783.01 Kb 00:03:37 00:01:51 00:01:37 00:00:48 00:00:04   Chapter5.pdf 429.22 Kb 00:01:59 00:01:01 00:00:53 00:00:26 00:00:02   Chapter6.pdf 121.08 Kb 00:00:33 00:00:17 00:00:15 00:00:07 < 00:00:01   Preface.pdf 645.81 Kb 00:02:59 00:01:32 00:01:20 00:00:40 00:00:03   References.pdf 56.13 Kb 00:00:15 00:00:08 00:00:07 00:00:03 < 00:00:01   Thesis.pdf 1.90 Mb 00:08:46 00:04:31 00:03:57 00:01:58 00:00:10