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Title: 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{sub CO}{sup ′} 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{sub CO}{sup ′} 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{sub IR}{sup tot} results in a mean L{sub IR}{sup SF}/L{sub CO}{sup ′} for our entire sample consistent with the mean L{sub IR}/L{sub CO}{sup ′} 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 luminousmore » infrared galaxies and find a consistent trend between L{sub 6.2}/L{sub IR}{sup SF} and L{sub IR}{sup SF}/L{sub CO}{sup ′}, such that small dust grain emission decreases with increasing L{sub IR}{sup SF}/L{sub CO}{sup ′} for both local and high-redshift dusty galaxies.« less
Authors:
; ; ; ; ;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomy, University of Massachusetts, Amherst, MA 01002 (United States)
  2. Instituto Nacional de Astrofísica, Optica y Electrónica, Apdos. Postales 51 y 216, C.P. 72000 Puebla, Pue. (Mexico)
  3. Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States)
  4. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  5. School of Astronomy and Space Science, Nanjing University, Nanjing, 210093 (China)
Publication Date:
OSTI Identifier:
22370112
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 796; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; COSMIC GASES; DUSTS; EFFICIENCY; EMISSION; GALAXIES; GALAXY NUCLEI; HYDROGEN; MOLECULES; POLYCYCLIC AROMATIC HYDROCARBONS; RED SHIFT; SPECTROSCOPY; STARS; TELESCOPES