5 research outputs found
AGN Feedback models: Correlations with star formation and observational implications of time evolution
We examine the correlation between the star formation rate (SFR) and black
hole accretion rate (BHAR) across a suite of different AGN feedback models,
using the time evolution of a merger simulation. By considering three different
stages of evolution, and a distinction between the nuclear and outer regions of
star formation, we consider 63 different cases. Despite many of the feedback
models fitting the M-\sigma\ relationship well, there are often distinct
differences in the SFR-BHAR correlations, with close to linear trends only
being present after the merger. Some of the models also show evolution in the
SFR-BHAR parameter space that is at times directly across the long-term
averaged SFR-BHAR correlation. This suggests that the observational SFR-BHAR
correlation found for ensembles of galaxies is an approximate statistical
trend, as suggested by Hickox et al. Decomposing the SFR into nuclear and outer
components also highlights notable differences between models and there is only
modest agreement with observational studies examining this in Seyfert galaxies.
For the fraction of the black hole mass growth from the merger event relative
to the final black hole mass, we find as much as a factor of three variation
among models. This also translates into a similar variation in the
post-starburst black hole mass growth. Overall, we find that while qualitative
features are often similar amongst models, precise quantitative analysis shows
there can be quite distinct differences.Comment: Accepted to MNRAS. Comments welcom
AGN feedback models: correlations with star formation and observational implications of time evolution
We examine the correlation between the star formation rate (SFR) and black hole accretion rate (BHAR) across a suite of different active galactic nuclei (AGN) feedback models, using the time evolution of a merger simulation. By considering three different stages of evolution, and a distinction between the nuclear and outer regions of star formation, we consider 63 different cases. Despite many of the feedback models fitting the M-σ relationship well, there are often distinct differences in the SFR-BHAR correlations, with close to linear trends only being present after the merger. Some of the models also show evolution in the SFR-BHAR parameter space that is at times directly across the long-term averaged SFR-BHAR correlation. This suggests that the observational SFR-BHAR correlation found for ensembles of galaxies is an approximate statistical trend, as suggested by Hickox etal. Decomposing the SFR into nuclear and outer components also highlights notable differences between models and there is only modest agreement with observational studies examining this in Seyfert galaxies. For the fraction of the black hole mass growth from the merger event relative to the final black hole mass, we find as much as a factor of 3 variation among models. This also translates into a similar variation in the post-starburst black hole mass growth. Overall, we find that while qualitative features are often similar amongst models, precise quantitative analysis shows there can be quite distinct difference
1ES 1927+654: a bare Seyfert 2
1ES 1927+654 is an active galactic nucleus (AGN) that appears to defy the
unification model. It exhibits a type-2 optical spectrum, but possesses little
X-ray obscuration. XMM-Newton and Suzaku observations obtained in 2011 are used
to study the X-ray properties of 1ES 1927+654. The spectral energy distribution
derived from simultaneous optical-to-X-ray data obtained with XMM-Newton shows
the AGN has a typical Eddington ratio (L/L_Edd = 0.014-0.11). The X-ray
spectrum and rapid variability are consistent with originating from a corona
surrounding a standard accretion disc. Partial covering models can describe the
x-ray data; however, the narrow Fe Ka emission line predicted from standard
photoelectric absorption is not detected. Ionized partial covering also favours
a high-velocity outflow (v ~ 0.3c), which requires the kinetic luminosity of
the wind to be >30 per cent of the bolometric luminosity of the AGN. Such
values are not unusual, but for 1ES 1927+654 it requires the wind is launched
very close to the black hole (~ 10 Rg). Blurred reflection models also work
well at describing the spectral and timing properties of 1ES 1927+654 if the
AGN is viewed nearly edge-on, implying that an inner accretion disc must be
present. The high inclination is intriguing as it suggests 1ES 1927+654 could
be orientated like a Seyfert 2, in agreement with its optical classification,
but viewed through a tenuous torus.Comment: 14 pages. Accepted for publication in MNRA