10,279 research outputs found
Chandra detection of a parsec scale wind in the Broad Line Radio Galaxy 3C 382
We present unambiguous evidence for a parsec scale wind in the Broad-Line
Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN, with , whereby an outflow has been measured with
X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C
382 has revealed the presence of several high ionization absorption lines in
the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are
blue-shifted with respect to the systemic velocity of 3C 382 by -840\pm60 km/s
and are resolved by Chandra with a velocity width of 340\pm70 km/s. The outflow
appears to originate from a single zone of gas of column density cm and ionization parameter . From
the above measurements we calculate that the outflow is observed on parsec
scales, within the likely range from 10-1000 pc, i.e., consistent with an
origin in the Narrow Line Region.Comment: 11 pages, accepted for publication in Astrophysical Journal Letter
The Global Implications of the Hard X-ray Excess in Type 1 AGN
Recent evidence for a strong 'hard excess' of flux at energies > 20 keV in
some Suzaku observations of type 1 Active Galactic Nuclei (AGN) has motivated
an exploratory study of the phenomenon in the local type 1 AGN population. We
have selected all type 1 AGN in the Swift Burst Alert Telescope (BAT) 58-month
catalog and cross-correlated them with the holdings of the Suzaku public
archive. We find the hard excess phenomenon to be a ubiquitous property of type
1 AGN. Taken together, the spectral hardness and equivalent width of Fe K alpha
emission are consistent with reprocessing by an ensemble of Compton-thick
clouds that partially cover the continuum source. In the context of such a
model, ~ 80 % of the sample has a hardness ratio consistent with > 50% covering
of the continuum by low-ionization, Compton-thick gas. More detailed study of
the three hardest X-ray spectra in our sample reveal a sharp Fe K absorption
edge at ~ 7 keV in each of them, indicating that blurred reflection is not
responsible for the very hard spectral forms. Simple considerations place the
distribution of Compton-thick clouds at or within the optical broad line
region.Comment: Accepted for publication in Ap
Evidence for a circum-nuclear and ionised absorber in the X-ray obscured BroadLine Radio Galaxy 3C 445
Here we present the results of a Suzaku observation of the Broad Line Radio
Galaxy 3C 445. We confirm the results obtained with the previous X-ray
observations which unveiled the presence of several soft X-ray emission lines
and an overall X-ray emission which strongly resembles a typical Seyfert 2
despite of the optical classification as an unobscured AGN. The broad band
spectrum allowed us to measure for the first time the amount of reflection
(R~0.9) which together with the relatively strong neutral Fe Kalpha emission
line (EW ~ 100 eV) strongly supports a scenario where a Compton-thick mirror is
present. The primary X-ray continuum is strongly obscured by an absorber with a
column density of NH =2-3 x10^{23} cm^{-2}. Two possible scenarios are proposed
for the absorber: a neutral partial covering or a mildly ionised absorber with
an ionisation parameter log\xi ~ 1.0 erg cm s^{-1}. A comparison with the past
and more recent X-ray observations of 3C 445 performed with XMM-Newton and
Chandra is presented, which provided tentative evidence that the ionised and
outflowing absorber varied. We argue that the absorber is probably associated
with an equatorial disk-wind located within the parsec scale molecular torus.Comment: Accepted by MNRAS; 13 pages, 6 figures, 4 table
Probing the cool ISM in galaxies via 21cm HI absorption
Recent targeted studies of associated HI absorption in radio galaxies are
starting to map out the location, and potential cosmological evolution, of the
cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21
cm absorption profiles often show two distinct spectral-line components:
narrow, deep lines arising from cold gas in the extended disc of the galaxy,
and broad, shallow lines from cold gas close to the AGN (e.g. Morganti et al.
2011). Here, we present results from a targeted search for associated HI
absorption in the youngest and most recently-triggered radio AGN in the local
universe (Allison et al. 2012b). So far, by using the recently commissioned
Australia Telescope Compact Array Broadband Backend (CABB; Wilson et al. 2011),
we have detected two new absorbers and one previously-known system. While two
of these show both a broad, shallow component and a narrow, deep component (see
Fig. 1), one of the new detections has only a single broad, shallow component.
Interestingly, the host galaxies of the first two detections are classified as
gas-rich spirals, while the latter is an early-type galaxy. These detections
were obtained using a spectral-line finding method, based on Bayesian
inference, developed for future large-scale absorption surveys (Allison et al.
2012a).Comment: 1 page, 1 figure, published in Proceedings of IAU Symposium No. 29
The Hard X-Ray View of Reflection, Absorption, and the Disk-Jet Connection in the Radio-Loud AGN 3C 33
We present results from Suzaku and Swift observations of the nearby radio
galaxy 3C 33, and investigate the nature of absorption, reflection, and jet
production in this source. We model the 0.5-100 keV nuclear continuum with a
power law that is transmitted either through one or more layers of pc-scale
neutral material, or through a modestly ionized pc-scale obscurer. The standard
signatures of reflection from a neutral accretion disk are absent in 3C 33:
there is no evidence of a relativistically blurred Fe K emission line,
and no Compton reflection hump above 10 keV. We find the upper limit to the
neutral reflection fraction is R<0.41 for an e-folding energy of 1 GeV. We
observe a narrow, neutral Fe K line, which is likely to originate at
least 2,000 R_s from the black hole. We show that the weakness of reflection
features in 3C 33 is consistent with two interpretations: either the inner
accretion flow is highly ionized, or the black-hole spin configuration is
retrograde with respect to the accreting material.Comment: 12 pages, 11 figures, 4 tables. Accepted for publication in Ap
Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers
The existence of ionized X-ray absorbing layers of gas along the line of
sight to the nuclei of Seyfert galaxies is a well established observational
fact. This material is systematically outflowing and shows a large range in
parameters. However, its actual nature and dynamics are still not clear. In
order to gain insights into these important issues we performed a literature
search for papers reporting the parameters of the soft X-ray warm absorbers
(WAs) in 35 type 1 Seyferts and compared their properties to those of the
ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources
with WAs is >60%, consistent with previous studies. The fraction of sources
with UFOs is >34%, >67% of which also show WAs. The large dynamic range
obtained when considering all the absorbers together allows us, for the first
time, to investigate general relations among them. In particular, we find
significant correlations indicating that the closer the absorber is to the
central black hole, the higher the ionization, column, outflow velocity and
consequently the mechanical power. The absorbers continuously populate the
whole parameter space, with the WAs and the UFOs lying always at the two ends
of the distribution. This strongly suggest that these absorbers, often
considered of different types, could actually represent parts of a single
large-scale stratified outflow observed at different locations from the black
hole. The observed parameters and correlations are consistent with both
radiation pressure through Compton scattering and MHD processes contributing to
the outflow acceleration, the latter playing a major role. Most of the
absorbers, especially the UFOs, have a sufficiently high mechanical power to
significantly contribute to AGN feedback.Comment: Manuscript updated to match the MNRAS published version. Link to the
related INAF news: http://www.media.inaf.it/2013/02/05/warm-absorbers
P04.66 Comparing attitudes preceding and succeeding complementary and alternative medicine and integrative medicine undergraduate courses
Non-contracting groups generated by (3,2)-automata
© Journal Algebra and Discrete Mathematics. We add to the classification of groups generated by 3-state automata over a 2-letter alphabet given by Bondarenko et al., by showing that a number of the groups in the classification are non-contracting. We show that the criterion we use to prove a self-similar action is non-contracting also implies that the associated self-similarity graph introduced by Nekrashevych is non-hyperbolic
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