1,095 research outputs found
A remarkable long-term light curve, and deep, low-state spectroscopy: Swift & XMM-Newton monitoring of the NLS1 galaxy Mkn 335
The Narrow-line Seyfert 1 galaxy (NLS1) Mkn 335 is remarkable because it has
repeatedly shown deep, long X-ray low-states which show pronounced spectral
structure. It has become one of the prototype AGN in deep minimum X-ray states.
Here we report on the continuation of our ongoing monitoring campaign with
Swift and the examination of the low state X-ray spectra based on a 200 ks
triggered observation with XMM in June 2009. Swift has continuously monitored
Mkn 335 since May 2007 typically on a monthly basis. This is one of the longest
simultaneous UV/X-ray light curves so far obtained for an active galactic
nucleus (AGN). Mkn 335 has shown strong X-ray variability even on time scales
of hours. In the UV, it turns out to be one of the most variable among NLS1s.
Long-term Swift monitoring allow us to examine correlations between the UV,
X-rays and X-ray hardness ratios. We find no significant correlation or lag
between the UV and X-ray variability; however, we do find distinct trends in
the behavior of the hardness ratio variability. The hardness ratio and count
rate are correlated in the low-flux state, but no correlation is seen in the
high-state. The X-ray low-state spectra of the 2007 and 2009 XMM observations
display significant spectral variability. We fit the X-ray spectra with a suite
of phenomenological models in order to characterize the data. The broad band
CCD spectrum can be fitted equally well with partial absorption and blurred
reflection models. These more complicated models are explored in further detail
in upcoming work.Comment: 23 pages, 8 figures, 4 Tables, ApJ Suppl. accepte
Mkn 1239: A highly polarized NLS1 with a steep X-ray spectrum and strong NeIX emission
We report the results of an XMM-Newton observation of the Narrow-Line Seyfert
1 galaxy Mkn 1239. This optically highly polarized AGN has one of the steepest
X-ray spectra found in AGN with alpha-X = +3.0 based on ROSAT PSPC data. The
XMM-Newton EPIC PN and MOS data confirm this steep X-ray spectrum. The PN data
are best-fit by a powerlaw with a partial covering absorption model suggesting
two light paths between the continuum source and the observer, one indirect
scattered one which is less absorbed and a highly absorbed direct light path.
This result agrees with the wavelength dependent degree of polarization in the
optical/UV band. Residuals in the X-ray spectra of all three XMM-Newton EPIC
detectors around 0.9 keV suggest the presence of an emission line feature, most
likely the Ne IX triplet. The detection of NeIX and the non-detection of
OVII/OVIII suggest a super-solar Ne/O ratio.Comment: Submitted to Aj, 11 pages, 8 figue
IC 3599 did it again: A second outburst of the X-ray transient Seyfert 1.9 Galaxy
We report on the Swift discovery of a second high-amplitude (factor 100)
outburst of the Seyfert 1.9 galaxy IC 3599, and discuss implications for
outburst scenarios. Swift detected this active galactic nucleus (AGN) again in
February 2010 in X-rays at a level of (1.50\plm0.11) W (0.2-2.0
keV), which is nearly as luminous as the first outburst detected with ROSAT in
1990. Optical data from the Catalina sky survey show that the optical emission
was already bright two years before the Swift X-ray high-state. Our new Swift
observations performed between 2013 and 2015 show that IC 3599 is currently
again in a very low X-ray flux state. This repeat optical and X-ray outburst,
and the long optical duration, suggest that IC 3599 is likely not a tidal
disruption event (TDE). Instead, variants of AGN-related variability are
explored. The data are consistent with an accretion disk instability around a
black hole of mass on the order 10--10 M; a value estimated
using several different methods.Comment: Accepted for publication in ApJ Letter, 6 pages, 1 table, 3 figure
Analysing the Suzaku Spectra of the Broad-Line Seyfert 1 Galaxy CBS 126
We analysed new simultaneous \emph{Suzaku} and \emph{Swift} data of the Broad
Line Seyfert 1 (BLS1) galaxy CBS 126. A clear Fe emission line and a strong
soft excess are present in the source spectra. We fit the spectra with a
relativistic reflection model and find the model tends to fit the data with a
high iron abundance possibly due to the large soft excess present. By checking
the difference and the RMS spectra, we find there is likely an absorption edge
at 0.89 keV, which might be caused by oxygen or neon. We also produced
an analysis of the time-resolved spectra in order to examine the existence of
the edge. Although high iron abundance is required more in the time-resolved
spectra, a model of solar iron abundance together with an absorption edge gives
a more physical explanation. Variation of the ionisation parameter is an
alternative, plausible explanation for the excess seen in the difference
spectra. It is difficult to know if there are warm absorbers in this source
from the current data. To further investigate the presence of possible warm
absorbers, higher signal-to-noise low-energy data are needed. The work
presented here tentatively suggests that the spectra of a BLS1 can be explained
by a relativistic reflection model similar to that often seen in their
narrow-line cousins.Comment: 10 pages, 12 figures, accepted for publication in MNRA
Seyfert galaxies with Swift: giant flares, rapid drops, and other surprises
Swift has initiated a new era of understanding the extremes of active
galactic nuclei (AGN) variability, their drivers and underlying physics. This
is based on its rapid response, high sensitivity, good spatial resolution, and
its ability to collect simultaneously X--ray-to-optical SEDs. Here, we present
results from our recent monitoring campaigns with Swift of highly variable AGN,
including outbursts, deep low states, and unusual long-term trends in several
Seyfert galaxies including Mrk 335, WPVS007, and RXJ2314.9+2243. We also report
detection of a new X-ray and optical outburst of IC 3599 and our Swift
follow-ups. IC 3599 was previously known as one of the AGN with the
highest-amplitude outbursts. We briefly discuss implications of this second
outburst of IC 3599 for emission scenarios including accretion-disk
variability, repeat tidal disruption events, and the presence of a binary
supermassive black hole.Comment: to appear in "Swift: 10 years of discovery", Proceedings of Scienc
The Gamma-Ray Detected Narrow-Line Seyfert 1 Galaxy 1H 0323+342: Swift Monitoring and Suzaku Spectroscopy
As a radio-loud narrow-line Seyfert 1 galaxy (NLS1) detected by Fermi/LAT in
GeV -rays, 1H 0323+342 is a remarkable Active Galactic Nucleus (AGN)
showing properties characteristic of both NLS1s and blazars. Here we present
results of simultaneous X-ray and UV/optical monitoring observations on 1H
0323+342 taken with the UV/Optical Telescope (UVOT) and X-ray Telescope (XRT)
onboard the Swift satellite over six years from 2006. Overall, the object
showed statistically correlated variations in both the UV and X-ray bands on
timescales of years as well as on timescales of days. A deep Suzaku observation
reveals X-ray variability on timescales as short as a few tens of thousand
seconds, and an X-ray spectrum typical of Seyfert galaxies. The broad-band
spectral energy distribution, for which the data of UV and X-ray observations
taken on 2009 July 26-27 were used, can be well modeled with a simple one-zone
leptonic jet model plus accretion disk/corona emission. The latter is
predominantly responsible for the UV/optical and X-ray (0.3-10 keV) emission
and their observed variations. The correlated UV-X-ray variability on the
timescale of days is consistent with reprocessing of the X-ray radiation by the
accretion disk. The shortest timescale and large normalized excess variance of
the X-ray variability detected with Suzaku suggest a relatively small black
hole mass of the order of , consistent with the estimation based
on the broad H line in the optical.Comment: 38 pages, 12 figures, in press, accepted by AJ (first submitted on
2014 July 7th
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