ALMA observations of cold molecular gas in AGN hosts at z ~ 1.5 – evidence of AGN feedback?

Sargent, Mark (2017) ALMA observations of cold molecular gas in AGN hosts at z ~ 1.5 – evidence of AGN feedback? Monthly Notices of the Royal Astronomical Society, 468 (4). pp. 4205-4215. ISSN 0035-8711

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Similarly to the cosmic star formation history, the black hole accretion rate density of the Universe peaked at 1<z<3. This cosmic epoch is hence best suited for investigating the effects of radiative feedback from AGN. Observational efforts are underway to quantify the impact of AGN feedback, if any, on their host galaxies. Here we present a study of the molecular gas content of AGN hosts at z~1.5 using CO[2-1] line emission observed with ALMA for a sample of 10 AGNs. We compare this with a sample of galaxies without an AGN matched in redshift, stellar mass, and star formation rate. We detect CO in 3 AGNs with $\mathrm{L_{CO} \sim 6.3-25.1\times 10^{9} L_{\odot}}$ which translates to a molecular hydrogen gas mass of $\mathrm{2.5-10\times 10^{10} M_{\odot}}$ assuming conventional conversion factor of $\mathrm{\alpha_{CO}}\sim3.6$. Our results indicate a >99% probability of lower depletion time scales and lower molecular gas fractions in AGN hosts with respect to the non-AGN comparison sample. We discuss the implications of these observations on the impact that AGN feedback may have on star formation efficiency of z>1 galaxies.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Depositing User: Mark Sargent
Date Deposited: 06 Jun 2017 08:12
Last Modified: 06 Jun 2017 08:16

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Project NameSussex Project NumberFunderFunder Ref
From gas to stars: 12 billion years of galaxy growthG1946-02Royal SocietyLT150041