1,180 research outputs found
An extended XMM-Newton observation of the Seyfert galaxy NGC 4051. I. Evidence for a shocked outflow
An extended XMM-Newton observation of the Seyfert 1 galaxy NGC 4051 has
revealed a rich absorption line spectrum indicating the presence of a
photoionized outflow with a wide range of velocities and ionization parameter.
At low continuum fluxes an emission line spectrum is well defined with both
narrow and broad components of several abundant metal ions. The absorption line
velocity structure and a broad correlation of velocity and ionization parameter
are consistent with an outflow scenario where a highly ionized, high velocity
wind, perhaps launched during intermittent super-Eddington accretion, runs into
the interstellar medium or previous ejecta, losing much of its kinetic energy
in the resultant strong shock. We explore the possibility that a quasi-constant
soft X-ray emission component may be evidence of this post-shock cooling. This
revised view of AGN outflows is consistent with multiple minor Eddington
accretion episodes creating a momentum-driven feedback linking black hole and
host galaxy growth.Comment: accepted for publication in Monthly Notices of the Royal Astronomical
Societ
Black Hole Winds
We show that black holes accreting at or above the Eddington rate probably
produce winds which are optically thick in the continuum, whether in quasars or
X-ray binaries. The photospheric radius and outflow speed are proportional to
\mo^2 and \mo^-1 respectively, where \mo is the mass outflow rate. The outflow
momentum rate is always of order L_Edd/c. Blackbody emission from these winds
may provide the big blue bump in some quasars and AGN, as well as ultrasoft
X-ray components in ULXs.Comment: 3 pages, no figures; MNRAS, in press (with minor corrections applied
An extended XMM-Newton observation of the Seyfert galaxy NGC 4051. II. Soft X-ray emission from a limb-brightened shell of post-shock gas
An extended XMM-Newton observation of the Seyfert I galaxy NGC 4051 in 2009
revealed a complex absorption spectrum, with a wide range of outflow velocities
and ionisation states.The main velocity and ionisation structure was
interpreted in Paper I in terms of a decelerating, recombining flow resulting
from the shocking of a still higher velocity wind colliding with the ISM or
slower moving ejecta. The high sensitivity of the XMM-Newton observation also
revealed a number of broad emission lines, all showing evidence of
self-absorption near the line cores. The line profiles are found here to be
consistent with emission from a limb-brightened shell of post-shock gas
building up ahead of the contact discontinuity. While the broad emission lines
remain quasi-constant as the continuum flux changes by an order of magnitude,
recombination continua of several H- and He-like ions are found to vary in
response to the continuum, providing an important key to scaling the ionised
flow.Comment: Accepted for publication in MNRA
Quantifying the fast outflow in the luminous Seyfert galaxy PG1211+143
We report two new XMM-Newton observations of PG1211+143 in December 2007,
again finding evidence of the fast outflow of highly ionised gas first detected
in 2001. Stacking the new spectra with those from two earlier XMM-Newton
observations reveals strong and broad emission lines of FeXXV and OVIII,
indicating the fast outflow to be persistent and to have a large covering
factor. This finding confirms a high mass rate for the ionised ouflow in
PG1211+143 and provides the first direct measurement of a wide angle,
sub-relativistic outflow from an AGN transporting mechanical energy with the
potential to disrupt the growth of the host galaxy. We suggest PG1211+143 may
be typical of an AGN in a rapid super-Eddington growth phase.Comment: Accepted for publication in MNRAS. Extended version with new figures
and table
Recommendations and comments concerning documentation on the microwave active spectrometer systems
There are no author-identified significant results in this report
The Locus of Highly Accreting AGNs on the M_BH--sigma Plane: Selections, Limitations, and Implications
We re-examine the locus of narrow line Seyfert 1 galaxies on the M_BH--sigma
(black hole mass--bulge velocity dispersion) plane in the light of the results
from large new optically selected samples. We find that (1) soft X-ray selected
NLS1s have a lower ratio of BH mass to \sigma^{4}_{[OIII]} than broad line
Seyfert 1 galaxies; this remains a robust statistical result contrary to recent
claims otherwise; (2) optically selected NLS1s have systematically lower
Eddington luminosity ratio compared to X-ray selected NLS1s; and (3) as a
result, the locus of NLS1s on the M_BH--sigma plane is affected by selection
effects. We argue that there is no single explanation for the origin of the
M_BH--sigma relation; instead tracks of galaxies on the M_BH--sigma plane
differ with redshift, consistent with the downsizing of AGN activity. If these
results at face value are incorrect, then the data imply that AGNs with high
Eddington accretion reside preferentially in relatively late type galaxies at
the present epoch, perhaps a more interesting result and a challenge to
theoretical models.Comment: To appear in Ap
AGN have Underweight Black Holes and Reach Eddington
Eddington outflows probably regulate the growth of supermassive black holes
(SMBH) in AGN. I show that effect of the Rayleigh--Taylor instability on these
outflows means that SMBH masses are likely to be a factor of a few below the relation in AGN. This agrees with the suggestion by Batcheldor (2010)
that the relation defines an upper limit to the black hole mass. I
further argue that observed AGN black holes must spend much of their lives
accreting at the Eddington rate. This is already suggested by the low observed
AGN fraction amongst all galaxies despite the need to grow to the masses
required by the Soltan relation, and is reinforced by the suggested low SMBH
masses. Most importantly, this is the simplest explanation of the recent
discovery by Tombesi et al (2010a, b) of the widespread incidence of massive
ultrafast X--ray outflows in a large sample of AGN.Comment: MNRAS, in pres
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