[seminar] Astro Journal Club on 29 April

[Oskari Miettinen]

Dear all,

The Astro Journal Club will be held on Wednesday at 10:15 in the seminar
room F-201 of the Physics Department. This time we will discuss about the
fuelling of active galactic nuclei.

Presenter: Ivan Delvecchio
Paper title: Galaxy pairs in the Sloan Digital Sky Survey - XII: The
fuelling mechanism of low excitation radio-loud AGN
Authors: Ellison, S. L., Patton, D. R., and Hickox, R. C.

Summary:
We investigate whether the fuelling of low excitation radio galaxies
(LERGs) is linked to major galaxy interactions. Our study utilizes a
sample of 10,800 spectroscopic galaxy pairs and 97 post-mergers selected
from the Sloan Digital Sky Survey with matches to multi-wavelength
datasets. The LERG fraction amongst interacting galaxies is a factor of
3.5 higher than that of a control sample matched in local galaxy density,
redshift and stellar mass. However, the LERG excess in pairs does not
depend on projected separation and remains elevated out to at least 500
kpc, suggesting that major mergers are not their main fuelling channel. In
order to identify the primary fuelling mechanism of LERGs, we compile
samples of control galaxies that are matched in various host galaxy and
environmental properties. The LERG excess is reduced, but not completely
removed, when halo mass or D4000 are included in the matching parameters.
However, when BOTH M_halo and D4000 are matched, there is no LERG excess
and the 1.4 GHz luminosities (which trace jet mechanical power) are
consistent between the pairs and control. In contrast, the excess of
optical and mid-IR selected AGN in galaxy pairs is unchanged when the
additional matching parameters are implemented. Our results suggest that
whilst major interactions may trigger optically and mid-IR selected AGN,
the gas which fuels the LERGs has two secular origins: one associated with
the large scale environment, such as accretion from the surrounding medium
or minor mergers, plus an internal stellar mechanism, such as winds from
evolved stars.

Link to the paper: http://adsabs.harvard.edu/abs/2015arXiv150406255E

Hope to see you all on Wednesday!

Best wishes,
Oskari