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ALMA resolves extended star formation in high-z AGN host galaxies

Lookup NU author(s): Dr Christopher HarrisonORCiD


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© 2016 The Authors. We present high-resolution (0.3 arcsec) Atacama Large Millimeter Array (ALMA) 870 μm imaging of five z ≈ 1.5-4.5 X-ray detected AGN (with luminosities of L2-8keV > 1042 erg s-1). These data provide a ≳20 times improvement in spatial resolution over single-dish restframe far-infrared (FIR) measurements. The sub-millimetre emission is extended on scales of FWHM ≈ 0.2 arcsec-0.5 arcsec, corresponding to physical sizes of 1-3 kpc (median value of 1.8 kpc). These sizes are comparable to the majority of z=1-5 sub-millimetre galaxies (SMGs) with equivalent ALMA measurements. In combination with spectral energy distribution analyses, we attribute this rest-frame FIR emission to dust heated by star formation. The implied star-formation rate surface densities are ≈20-200 Mγ yr-1 kpc-2, which are consistent with SMGs of comparable FIR luminosities (i.e. LIR ≈ [1-5] × 1012 Lγ). Although limited by a small sample of AGN, which all have high-FIR luminosities, our study suggests that the kpc-scale spatial distribution and surface density of star formation in high-redshift star-forming galaxies is the same irrespective of the presence of X-ray detected AGN.

Publication metadata

Author(s): Harrison CM, Simpson JM, Stanley F, Alexander DM, Daddi E, Mullaney JR, Pannella M, Rosario DJ, Smail I

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society: Letters

Year: 2016

Volume: 457

Issue: 1

Pages: L122-L126

Print publication date: 21/03/2016

Online publication date: 01/02/2016

Acceptance date: 04/01/2016

ISSN (print): 1745-3925

ISSN (electronic): 1745-3933

Publisher: Oxford University Press


DOI: 10.1093/mnrasl/slw001


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