[seminar] Astro Journal Club on 2 December

[Oskari Miettinen]

Dear all,

Our Astro Journal Club will be held on Wednesday at 3:00 pm (sharp) in the
seminar room F-201 of the Physics Department. This time we will discuss
about the relationship between the X-ray luminosity and star formation
rate in dusty active galactic nuclei.

Presenter: Monika Herceg
Paper title: The Relationship between black hole accretion and host star
formation in dusty AGNs
Authors: Dai, Y. S., Wilkes, B. J., Bergeron, J., et al.

Summary:
We study the relationship between the X-ray luminosity and star formation
rate (SFR) in an unbiased sample of dusty active galactic nuclei (AGNs),
detected in both the hard X-ray and far-infrared (IR) bands in the XMM-LSS
field. The sample consists of 451 AGNs with spectroscopic redshifts of
0.04 < z <3.3, and spans an X-ray luminosity range of L(2-10keV)=1.0e41-45
erg/s. We find a positive correlation between the X-ray luminosity and SFR
derived from AGN-removed IR luminosity. We find that binning the sample by
SFR instead of LX results in a more positive correlation. This is
consistent with the scenario in which the shorter variability time scale
of AGN than star formation flattens the observed correlation between AGN
and star formation. We do not find significant diversity in the observed
correlation when considering subsets selected based on supermassive black
hole mass or Eddington ratio, indicating that AGN accretion has at most a
limited effect on the SFR-Lx relation. Comparing to results in the
literature, we propose a picture in which the correlation depends on
sample composition. Additionally, we find a constant ratio between the SFR
and the black hole accretion rate (BHAR) of log(SFR/BHAR)=(3.03+/-0.55).
This value coincides with the ratio between galaxy bulge/total stellar
mass and SMBH mass found in the local universe. Our results are consistent
with the secular evolution scenario, in which dusty AGNs are coevolving
with the host from the same gas supply at a constant rate regardless of
accretion activity.

Link to the paper: http://adsabs.harvard.edu/abs/2015arXiv151106761D

Hope to see you all on Wednesday!

Cheers,
Oskari