EARLY SCIENCE WITH THE LARGE MILLIMETER TELESCOPE: EXPLORING THE EFFECT OF AGN ACTIVITY ON THE RELATIONSHIPS BETWEEN MOLECULAR GAS, DUST, AND STAR FORMATION

The molecular gas, H sub(2), that fuels star formation in galaxies is difficult to observe directly. As such, the ratio of L sub(IR) to L super(l) sub(CO) is an observational estimate of the star formation rate compared with the amount of molecular gas available to form stars, which is related to th...

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Bibliographic Details
Published in:The Astrophysical journal 2014-12, Vol.796 (2), p.1-13
Main Authors: Kirkpatrick, Allison, Pope, Alexandra, ARETXAGA, ITZIAR, Armus, Lee, Calzetti, Daniela, Helou, George, Montana, Alfredo, Narayanan, Gopal, Schloerb, F Peter, Shi, Yong, Vega, Olga, Yun, Min S
Format: Article
Language:English
Subjects:
Active galactic nuclei
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CARBON MONOXIDE
Cobalt
COMPARATIVE EVALUATIONS
COSMIC GASES
Dust
DUSTS
EFFICIENCY
EMISSION
GALAXIES
GALAXY NUCLEI
HYDROGEN
MOLECULES
POLYCYCLIC AROMATIC HYDROCARBONS
RED SHIFT
Searching
SPECTROSCOPY
Star formation
STARS
TELESCOPES
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Summary:The molecular gas, H sub(2), that fuels star formation in galaxies is difficult to observe directly. As such, the ratio of L sub(IR) to L super(l) sub(CO) is an observational estimate of the star formation rate compared with the amount of molecular gas available to form stars, which is related to the star formation efficiency and the inverse of the gas consumption timescale. We test what effect an IR luminous active galactic nucleus (AGN) has on the ratio L sub(IR)/L super(l ) sub(CO) in a sample of 24 intermediate redshift galaxies from the 5 mJy Unbiased Spitzer Extragalactic Survey (5MUSES). We obtain new CO(1-0) observations with the Redshift Search Receiver on the Large Millimeter Telescope. We diagnose the presence and strength of an AGN using Spitzer IRS spectroscopy. We find that removing the AGN contribution to L super(tot) sub(IR) results in a mean L super(SF) sub(IR)/L super(l) sub(CO) for our entire sample consistent with the mean L sub(IR)/L super(l ) sub(CO) derived for a large sample of star forming galaxies from z ~ 0-3. We also include in our comparison the relative amount of polycyclic aromatic hydrocarbon emission for our sample and a literature sample of local and high-redshift ultra luminous infrared galaxies and find a consistent trend between L sub(6.2)/L super(SF) sub(IR) and L super(SF) sub(IR)/L super(l) sub(CO), such that small dust grain emission decreases with increasing L super(SF) sub(IR)/L super(l) sub(CO) for both local and high-redshift dusty galaxies.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/796/2/135