Sub-Eddington super-massive black hole activity in Fornax early type galaxies. (arXiv:1902.03328v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lee_N/0/1/0/all/0/1">Nathan Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gallo_E/0/1/0/all/0/1">Elena Gallo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hodges_Kluck_E/0/1/0/all/0/1">Edmund Hodges-Kluck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cote_P/0/1/0/all/0/1">Patrick Côté</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferrarese_L/0/1/0/all/0/1">Laura Ferrarese</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miller_B/0/1/0/all/0/1">Brendan Miller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baldassare_V/0/1/0/all/0/1">Vivienne Baldassare</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Plotkin_R/0/1/0/all/0/1">Rich Plotkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Treu_T/0/1/0/all/0/1">Tommaso Treu</a>
We characterize the incidence and intensity of low-level super-massive black
hole activity within the Fornax cluster, through X-ray observations of the
nuclei of 29 quiescent early-type galaxies. Using the textit{Chandra X-ray
Telescope}, we target 17 galaxies from the HST Fornax Cluster Survey, down to a
uniform (3$sigma$) limiting X-ray luminosity threshold of
$5cdot10^{38}$ergs$^{-1}$, which we combine with deeper, archival observations
for an additional 12 galaxies. A nuclear X-ray point-source is detected in 11
out of 29 targets. After accounting for the low mass X-ray binary contamination
to the nuclear X-ray signal, the X-ray active fraction is measured at $26.6%
pm 9.6%$. The results from this analysis are compared to similar
investigations targeting quiescent early types in the Virgo cluster, as well as
the field. After correcting for the different mass distributions, the measured
Fornax active fraction is less than the field fraction, at more than 3$sigma$,
confirming that the funneling of gas to the nuclear regions of cluster members
is inhibited compared to those galaxies in the field. At the same time, we find
no statistically significant difference between Fornax and Virgo galaxies, with
only marginal evidence for a lower active fraction in Fornax (1 $sigma$); if
real, owing to Fornax’s higher galaxy number density, this could indicate that
galaxy-galaxy interactions are more effective at gas removal than galaxy-gas
effects.
We characterize the incidence and intensity of low-level super-massive black
hole activity within the Fornax cluster, through X-ray observations of the
nuclei of 29 quiescent early-type galaxies. Using the textit{Chandra X-ray
Telescope}, we target 17 galaxies from the HST Fornax Cluster Survey, down to a
uniform (3$sigma$) limiting X-ray luminosity threshold of
$5cdot10^{38}$ergs$^{-1}$, which we combine with deeper, archival observations
for an additional 12 galaxies. A nuclear X-ray point-source is detected in 11
out of 29 targets. After accounting for the low mass X-ray binary contamination
to the nuclear X-ray signal, the X-ray active fraction is measured at $26.6%
pm 9.6%$. The results from this analysis are compared to similar
investigations targeting quiescent early types in the Virgo cluster, as well as
the field. After correcting for the different mass distributions, the measured
Fornax active fraction is less than the field fraction, at more than 3$sigma$,
confirming that the funneling of gas to the nuclear regions of cluster members
is inhibited compared to those galaxies in the field. At the same time, we find
no statistically significant difference between Fornax and Virgo galaxies, with
only marginal evidence for a lower active fraction in Fornax (1 $sigma$); if
real, owing to Fornax’s higher galaxy number density, this could indicate that
galaxy-galaxy interactions are more effective at gas removal than galaxy-gas
effects.
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