559 research outputs found
Relativistic spectroscopy of the extreme NLS1 IRAS13224-3809
The narrow line Seyfert 1 (NLS1) IRAS 13224-3809 is the most X-ray variable
active galactic nucleus (AGN), exhibiting 0.3-10 keV flux changes of over an
order of magnitude within an hour. We report on the results of the 1.5 Ms 2016
XMM-Newton/NuSTAR observing campaign, which revealed the presence of a 0.24c
ultra-fast outflow in addition to the well-known strong relativistic
reflection. We also summarise other key results of the campaign, such as the
first detection of a non-linear RMS-flux relation in an accreting source,
correlations between outflow absorption strength/velocity and source flux, and
a disconnect between the X-ray and UV emission. Our results are consistent with
a scenario where a disk wind is launched close to the black hole, imprinting
absorption features into the spectrum and variability.Comment: 6 pages, 7 figures, contributed talk at "Revisiting narrow-line
Seyfert 1 galaxies and their place in the Universe" (Padova, April 2018).
Accepted for publication in Proceedings of Science, PoS(NLS1-2018)03
Disentangling the Complex Broadband X-ray Spectrum of IRAS 13197-1627 with NuSTAR, XMM-Newton and Suzaku
We present results from a coordinated -+ observation of
the type 1.8 Seyfert galaxy IRAS 13197-1627. This is a highly complex source,
with strong contributions from relativistic reflection from the inner accretion
disk, neutral absorption and further reprocessing by more distant material, and
ionised absorption from an outflow. We undertake a detailed spectral analysis
combining the broadband coverage provided by -+ with a
multi-epoch approach incorporating archival observations performed by
- and . Our focus is on characterising the reflection from
the inner accretion disk, which previous works have suggested may dominate the
AGN emission, and constraining the black hole spin. Using lamppost disk
reflection models, we find that the results for the inner disk are largely
insensitive to assumptions regarding the geometry of the distant reprocessor
and the precise form of the illuminating X-ray continuum. However, these
results do depend on the treatment of the iron abundance of the distant
absorber/reprocessor. The multi-epoch data favour a scenario in which the AGN
is chemically homogeneous, and we find that a rapidly rotating black hole is
preferred, with , but a slowly-rotating black hole is not
strongly excluded. In addition to the results for the inner disk, we also find
that both the neutral and ionised absorbers vary from epoch to epoch, implying
that both have some degree of inhomogeneity in their structure.Comment: 15 pages, 7 figures, accepted for publication in MNRA
-Scale Decoupling of the Mechanical Relaxation and Diverging Shear Wave Propagation Lengthscale in Triphenylphosphite
We have performed depolarized Impulsive Stimulated Scattering experiments to
observe shear acoustic phonons in supercooled triphenylphosphite (TPP) from
10 - 500 MHz. These measurements, in tandem with previously performed
longitudinal and shear measurements, permit further analyses of the relaxation
dynamics of TPP within the framework of the mode coupling theory (MCT). Our
results provide evidence of coupling between the shear and
longitudinal degrees of freedom up to a decoupling temperature = 231 K. A
lower bound length scale of shear wave propagation in liquids verified the
exponent predicted by theory in the vicinity of the decoupling temperature
A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN
Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, ... See full text for complete abstrac
The Compton hump and variable blue wing in the extreme low-flux NuSTAR observations of 1H0707-495
The Narrow-line Seyfert I galaxy, 1H0707-495, has been well observed in the
0.3-10 keV band, revealing a dramatic drop in flux in the iron K alpha band, a
strong soft excess, and short timescale reverberation lags associated with
these spectral features. In this paper, we present the first results of a deep
250 ks NuSTAR observation of 1H0707-495, which includes the first sensitive
observations above 10 keV. Even though the NuSTAR observations caught the
source in an extreme low-flux state, the Compton hump is still significantly
detected. NuSTAR, with its high effective area above 7 keV, clearly detects the
drop in flux in the iron K alpha band, and by comparing these observations with
archival XMM-Newton observations, we find that the energy of this drop
increases with increasing flux. We discuss possible explanations for this, the
most likely of which is that the drop in flux is the blue wing of the
relativistically broadened iron K alpha emission line. When the flux is low,
the coronal source height is low, thus enhancing the most gravitationally
redshifted emission.Comment: Submitted to MNRAS, comments are welcome. 9 pages, 5 figure
An X-Ray View of the Jet-Cycle in the Radio Loud AGN 3C120
We present a study of the central engine in the broad-line radio galaxy 3C120
using a multi-epoch analysis of a deep XMM-Newton observation and two deep
Suzaku pointings (in 2012). In order to place our spectral data into the
context of the disk-disruption/jet-ejection cycles displayed by this object, we
monitor the source in the UV/X-ray bands, and in the radio band. We find three
statistically acceptable spectral models, a disk-reflection model, a jet-model
and a jet+disk model. Despite being good descriptions of the data, the
disk-reflection model violates the radio constraints on the inclination, and
the jet-model has a fine-tuning problem, requiring a jet contribution exceeding
that expected. Thus, we argue for a composite jet+disk model. Within the
context of this model, we verify the basic predictions of the jet-cycle
paradigm, finding a truncated/refilling disk during the Suzaku observations and
a complete disk extending down to the innermost stable circular orbit (ISCO)
during the XMM-Newton observation. The idea of a refilling disk is further
supported by the detection of the ejection of a new jet knot approximately one
month after the Suzaku pointings. We also discover a step-like event in one of
the Suzaku pointings in which the soft band lags the hard band. We suggest that
we are witnessing the propagation of a disturbance from the disk into the jet
on a timescale set by the magnetic field.Comment: 14 pages, 10 figures, accepted for publication in Ap
Observations of MCG-5-23-16 with Suzaku, XMM-Newton and NuSTAR: Disk tomography and Compton hump reverberation
MCG-5-23-16 is one of the first AGN where relativistic reverberation in the
iron K line originating in the vicinity of the supermassive black hole was
found, based on a short XMM-Newton observation. In this work, we present the
results from long X-ray observations using Suzaku, XMM-Newton and NuSTAR
designed to map the emission region using X-ray reverberation. A relativistic
iron line is detected in the lag spectra on three different time-scales,
allowing the emission from different regions around the black hole to be
separated. Using NuSTAR coverage of energies above 10 keV reveals a lag between
these energies and the primary continuum, which is detected for the first time
in an AGN. This lag is a result of the Compton reflection hump responding to
changes in the primary source in a manner similar to the response of the
relativistic iron K line.Comment: Accepted for Publication in Ap
NuSTAR Reveals the Comptonizing Corona of the Broad-Line Radio Galaxy 3C 382
Broad-line radio galaxies (BLRGs) are active galactic nuclei that produce
powerful, large-scale radio jets, but appear as Seyfert 1 galaxies in their
optical spectra. In the X-ray band, BLRGs also appear like Seyfert galaxies,
but with flatter spectra and weaker reflection features. One explanation for
these properties is that the X-ray continuum is diluted by emission from the
jet. Here, we present two NuSTAR observations of the BLRG 3C 382 that show
clear evidence that the continuum of this source is dominated by thermal
Comptonization, as in Seyfert 1 galaxies. The two observations were separated
by over a year and found 3C 382 in different states separated by a factor of
1.7 in flux. The lower flux spectrum has a photon-index of
, while the photon-index of the higher flux
spectrum is . Thermal and anisotropic
Comptonization models provide an excellent fit to both spectra and show that
the coronal plasma cooled from keV in the low flux data to
keV in the high flux observation. This cooling behavior is
typical of Comptonizing corona in Seyfert galaxies and is distinct from the
variations observed in jet-dominated sources. In the high flux observation,
simultaneous Swift data are leveraged to obtain a broadband spectral energy
distribution and indicates that the corona intercepts % of the optical
and ultraviolet emitting accretion disk. 3C 382 exhibits very weak reflection
features, with no detectable relativistic Fe K line, that may be best
explained by an outflowing corona combined with an ionized inner accretion
disk.Comment: 8 pages, 8 figures, accepted by Ap
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