J/MNRAS/470/755 Galaxy mergers and AGN activity (Hewlett+, 2017)
The redshift evolution of major merger triggering of luminous AGNs:
a slight enhancement at z ∼ 2.
Hewlett T., Villforth C., Wild V., Mendez-Abreu J., Pawlik M., Rowlands K.
<Mon. Not. R. Astron. Soc., 470, 755-770 (2017)>
=2017MNRAS.470..755H 2017MNRAS.470..755H (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Photometry ; Morphology
Keywords: galaxies: active - galaxies: interactions - X-rays: galaxies
Abstract:
Active galactic nuclei (AGNs), particularly the most luminous AGNs,
are commonly assumed to be triggered through major mergers; however,
observational evidence for this scenario is mixed. To investigate any
influence of galaxy mergers on AGN triggering and luminosities through
cosmic time, we present a sample of 106 luminous X-ray-selected type 1
AGNs from the COSMOS survey. These AGNs occupy a large redshift range
(0.5<z<2.2) and two orders of magnitude in X-ray luminosity
(∼1043-1045erg/s). AGN hosts are carefully mass and redshift
matched to 486 control galaxies. A novel technique for identifying and
quantifying merger features in galaxies is developed, subtracting
GALFIT galaxy models and quantifying the residuals. Comparison to
visual classification confirms this measure reliably picks out
disturbance features in galaxies. No enhancement of merger features
with increasing AGN luminosity is found with this metric, or by visual
inspection. We analyse the redshift evolution of AGNs associated with
galaxy mergers and find no merger enhancement in lower redshift bins.
Contrarily, in the highest redshift bin (z∼2) AGNs are ∼4 times more
likely to be in galaxies exhibiting evidence of morphological
disturbance compared to control galaxies, at 99 per cent confidence
level (∼2.4σ) from visual inspection. Since only ∼15 per cent of
these AGNs are found to be in morphologically disturbed galaxies, it
is implied that major mergers at high redshift make a noticeable but
subdominant contribution to AGN fuelling. At low redshifts, other
processes dominate and mergers become a less significant triggering
mechanism.
Description:
High-resolution HST images of 106 X-ray-selected AGNs and 486 host
galaxy mass and redshift-matched control galaxies from the COSMOS
survey are analysed. Artificial AGNs (stars), matched in apparent
magnitude to the relevant AGNs, are placed into control galaxies to
make images equivalent. A new method for detecting disturbance in
galaxies is developed
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
agnsamp.dat 97 106 AGN sample
control.dat 97 486 Control sample
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See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
J/ApJS/172/29 : XMM-Newton survey in COSMOS field. I. (Hasinger+, 2007)
J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS field (Cappelluti+ 2009)
Byte-by-byte Description of file: agnsamp.dat control.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- XID Identification number,
XMMC NNNN in Simbad for AGN,
COSMOS NNNNNNN in Simbad for galaxies
9- 16 F8.4 deg RAdeg Right ascension (J2000)
18- 24 F7.5 deg DEdeg Declination (J2000)
26- 32 F7.4 mag mPS Point source magnitude
34- 39 F6.4 mag e_mPS rms uncertainty on mPS
41- 48 F8.4 mag mGal ?=-99 Galaxy magnitude
50- 57 F8.4 mag e_mGal ?=-99 rms uncertainty on mGal
59- 68 F10.6 kpc Re ?=-99 Effective radius
70- 79 F10.6 kpc e_Re ?=-99 rms uncertainty on Re
81- 88 F8.4 --- n ?=-99 Sersic number
90- 97 F8.4 --- e_n ?=-99 rms uncertainty on n
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Apr-2020