Submillimeter Surveys of Galaxy Samples

Author: Yang, Min

Year: 2007

Degree: Dissertation (Ph.D.)

Advisor: Phillips, Thomas G.

Committee Members: Phillips, Thomas G.; Blain, Andrew W.; Soifer, B. Thomas; Zmuidzinas, Jonas

Option: Physics; Social Science

DOI: 10.7907/ZTAY-AM05

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 350μm 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).

The first galaxy sample consists of 18 luminous infrared galaxies (LIGs) in the local Universe (0.003 ≤ z ≤ 0.042). We estimate the global properties in this galaxy sample; dust temperature (Td = 38.6 ± 7.7 K), emissivity index (β = 1.6 ± 0.3), far-infrared (FIR) luminosity (Lfir = 1011.2±0.6 L☉}) and dust mass (Md = 107.4±0.6 M☉). Guided by theoretical considerations and laboratory measurements, we derive a Td-β inverse correlation for the local LIG sample; Td = [5.03 x 109]1/4.46 + β.

The 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 350μm data, in combination with the pre-existing IRAS 60μm and 100μm data, leads to meaningful estimates of the global properties in these galaxies for the first time; Td = 40.9 ± 6.9K, Lfir = 1012.2±0.5 L☉, Md = 108.3±0.3 M☉ and intense starburst activity (SFR = 102.5±0.5 L☉ yr-1). There is strong circumstantial evidence that the Td-β 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.

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