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56
Sep 18, 2013
09/13
by
C. C. Cheung; L. Stawarz; A. Siemiginowska
texts
eye 56
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A newly identified kiloparsec-scale X-ray jet in the high-redshift z=3.89 quasar 1745+624 is studied with multi-frequency Very Large Array, Hubble Space Telescope, and Chandra X-ray imaging data. This is only the third large-scale X-ray jet beyond z>3 known and is further distinguished as being the most luminous relativistic jet observed at any redshift, exceeding 10^45 erg/s in both the radio and X-ray bands. Apart from the jet's extreme redshift, luminosity, and high inferred equipartition...
Source: http://arxiv.org/abs/astro-ph/0606255v2
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19
Jun 28, 2018
06/18
by
A. Simionescu; Ł. Stawarz; Y. Ichinohe; C. C. Cheung; M. Jamrozy; A. Siemiginowska; K. Hagino; P. Gandhi; N. Werner
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eye 19
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A recent Chandra observation of the nearby galaxy cluster Abell 585 has led to the discovery of an extended X-ray jet associated with the high-redshift background quasar B3 0727+409, a luminous radio source at redshift z=2.5. This is one of only few examples of high-redshift X-ray jets known to date. It has a clear extension of about 12", corresponding to a projected length of ~100 kpc, with a possible hot spot located 35" from the quasar. The archival high resolution VLA maps...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1509.04822
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45
Sep 24, 2013
09/13
by
A. Comastri; G. M. Stirpe; C. Vignali; W. N. Brandt; K. M. Leighly; F. Fiore; M. Guainazzi; G. Matt; F. Nicastro; E. M. Puchnarewicz; A. Siemiginowska
texts
eye 45
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The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5m telescope at La Silla. The 0.1-10 keV X-ray spectrum is characterized by a strong soft component which is best described by blackbody-like emission with a temperature of about 160 eV. At higher energies a steep (Gamma = 2.4) power-law tail is present. There is evidence of an ionized reflector in the form of an iron line and edge. We do not find...
Source: http://arxiv.org/abs/astro-ph/0010476v1
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70
Sep 22, 2013
09/13
by
E. M. Puchnarewicz; K. O. Mason; A. Siemiginowska; A. Fruscione; A. Comastri; F. Fiore; I. Cagnoni
texts
eye 70
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We present a comprehensive study of the spectrum of the narrow-line Seyfert 1 galaxy RE J1034+396, summarizing the information obtained from the optical to X-rays with observations from the William Herschel 4.2m Telescope (WHT), the Hubble Space Telescope, the Extreme UltraViolet Explorer, ROSAT, ASCA and BeppoSAX. The BeppoSAX spectra reveal a soft component which is well-represented by two blackbodies with kT of about 60 eV and 160 eV, mimicking that expected from a hot, optically-thick...
Source: http://arxiv.org/abs/astro-ph/0011389v1
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44
Sep 18, 2013
09/13
by
M. A. Sobolewska; A. Siemiginowska; M. Gierlinski
texts
eye 44
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Active galactic nuclei (AGN) and galactic black hole binaries (GBHs) represent two classes of accreting black holes. They both contain an accretion disc emitting a thermal radiation, and a non-thermal X-ray emitting corona. GBHs exhibit state transitions, and their spectral states are characterized by different luminosity levels and shapes of the spectral energy distribution (SED). If AGN transitioned in a similar way, the characteristic timescales of such transitions would exceed ~10^5 years....
Source: http://arxiv.org/abs/1102.0798v1
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71
Sep 18, 2013
09/13
by
G. Salvesen; J. M. Miller; E. Cackett; A. Siemiginowska
texts
eye 71
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We report on an XMM-Newton observation of the z=1.055 quasar and Giga-hertz Peaked Spectrum (GPS) source 3C 287. Our 62.3 ksec observation provides an exceptional X-ray view of a prominent member of this important subclass of active galactic nuclei (AGN). The X-ray spectra of 3C 287 are consistent with a simple absorbed power-law with a spectral index of Gamma = 1.72 +/- 0.02. Our fits imply a bolometric luminosity of L = 5.8 +/- 0.2 E+45 erg/s over the 0.3-10.0 keV band; this gives a mass...
Source: http://arxiv.org/abs/0809.4691v1
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64
Sep 22, 2013
09/13
by
T. L. Aldcroft; A. Siemiginowska; M. Elvis; S. Mathur; F. Nicastro; S. S. Murray
texts
eye 64
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The red quasar 3C 212 (z=1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C 212 for 19.5 ksec, resulting in a net detection of ~4000 counts. The Chandra data confirm the presence of an excess absorbing column N_H ~ 4 x 10^21 cm^-2 at the quasar redshift, but we find no compelling evidence for a warm absorber. Using both the Chandra and archival ROSAT...
Source: http://arxiv.org/abs/astro-ph/0307397v1
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50
Sep 21, 2013
09/13
by
M. Guainazzi; A. Siemiginowska; P. Rodriguez-Pascual; C. Stanghellini
texts
eye 50
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We report the XMM-Newton discovery of the first Compton-thick obscured AGN in a Broad Line Radio Galaxy, the Gigahertz Peaked-Spectrum source Mkn668 (OQ+208). The remarkably flat 2-10 keV X-ray spectrum (observed photon index, \Gamma ~ 0.7), alongside with a prominent iron K-alpha fluorescent emission line, is a clear signature of a Compton-reflection dominated spectrum. Mkn688 represents a remarkable example of discrepancy between X-ray spectral properties and optical classification, as its...
Source: http://arxiv.org/abs/astro-ph/0402639v1
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59
Sep 22, 2013
09/13
by
M. A. Sobolewska; M. Gierlinski; A. Siemiginowska
texts
eye 59
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We draw a comparison between AGN and Galactic black hole binaries using a uniform description of spectral energy distribution of these two classes of accreting X-ray sources. We parametrize spectra of GBHs with an alpha_GBH parameter which we define as a slope of a nominal power law function between 3 and 20 keV. We show that this parameter can be treated as an equivalent of the X-ray loudness, alpha_OX, used to describe AGN spectra. We do not find linear correlation between the alpha_GBH and...
Source: http://arxiv.org/abs/0901.2150v1
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38
Sep 22, 2013
09/13
by
H. L. Marshall; M. J. Hardcastle; M. Birkinshaw; J. Croston; D. Evans; H. Landt; E. Lenc; F. Massaro; E. S. Perlman; D. A. Schwartz; A. Siemiginowska; Ł. Stawarz; C. M. Urry; D. M. Worrall
texts
eye 38
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A Chandra X-ray imaging observation of the jet in Pictor A showed a feature that appears to be a flare that faded between 2000 and 2002. The feature was not detected in a follow-up observation in 2009. The jet itself is over 150 kpc long and a kpc wide, so finding year-long variability is surprising. Assuming a synchrotron origin of the observed high-energy photons and a minimum energy condition for the outflow, the synchrotron loss time of the X-ray emitting electrons is of order 1200 yr,...
Source: http://arxiv.org/abs/1004.0191v1
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58
Jul 20, 2013
07/13
by
E. Hatziminaoglou; A. Siemiginowska; M. Elvis
texts
eye 58
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We have developed a consistent analytical model to describe the observed evolution of the quasar luminosity function. Our model combines black hole mass distributions based on the Press - Schechter theory of the structure formation in the Universe with quasar luminosity functions resulting from a physics-based emission model that takes into account the time-dependent phenomena occurring in the accretion disks. Quasar evolution and CDM models are mutually constraining, therefore our model gives...
Source: http://arxiv.org/abs/astro-ph/0009105v1
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44
Sep 19, 2013
09/13
by
S. Pellegrini; A. Siemiginowska; G. Fabbiano; M. Elvis; L. Greenhill; R. Soria; A. Baldi; D. W. Kim
texts
eye 44
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The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821 hosts an extreme example of a quiescent central massive black hole, for which deep Chandra observations revealed a nuclear source for the first time (with L(2-10 keV)/L_Edd ~ 3.6X10^{-8}). We present here a multiwavelength study of this nucleus, including VLA observations that detect a radio counterpart to the Chandra nuclear source at 1.4 GHz, with a flux density of 127 $\mu$m and possibly a flat spectral shape; we also...
Source: http://arxiv.org/abs/astro-ph/0701642v2
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52
Sep 22, 2013
09/13
by
L. Stawarz; Y. T. Tanaka; G. Madejski; S. P. O'Sullivan; C. C. Cheung; I. J. Feain; Y. Fukazawa; P. Gandhi; M. J. Hardcastle; J. Kataoka; M. Ostrowski; B. Reville; A. Siemiginowska; A. Simionescu; T. Takahashi; Y. Takei; Y. Takeuchi; N. Werner
texts
eye 52
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[abridged] We report on Suzaku observations of selected regions within the Southern giant lobe of the radio galaxy Centaurus A. We focus on distinct X-ray features likely associated with fine radio structure of the lobe. We find that the spectral properties of the detected X-ray features are equally consistent with thermal emission from hot gas, or with a power-law radiation continuum. However, the plasma parameters implied by these different models favor a synchrotron origin for the analyzed...
Source: http://arxiv.org/abs/1210.4237v3
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49
Sep 23, 2013
09/13
by
B. Czerny; M. Moscibrodzka; D. Proga; T. Das; A. Siemiginowska
texts
eye 49
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Sgr A* is a source of strongly variable emission in several energy bands. It is generally agreed that this emission comes from the material surrounding the black hole which is either falling in or flowing out. The activity must be driven by accretion but the character of accretion flow in this object is an open question. We suggest that the inflow is dominated by the relatively low angular momentum material originating in one of the nearby group of stars. Such material flows in directly towards...
Source: http://arxiv.org/abs/0710.2426v2
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50
Sep 22, 2013
09/13
by
L. Stawarz; A. Siemiginowska; M. Ostrowski; M. Sikora
texts
eye 50
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The energy content of large-scale jets in FR I radio galaxies is still an open issue. Here we show that upper limits on the high-energy and very high-energy gamma-ray emission of the kpc-scale jet in M 87 radio galaxy imposed by EGRET, Whipple, and - most importantly - HEGRA and HESS observations, provide important constraints on the magnetic field strength in this object. In particular, a non-detection of gamma-ray radiation from the brightest part of this jet (knot A), expected from the...
Source: http://arxiv.org/abs/astro-ph/0501612v1
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52
Sep 19, 2013
09/13
by
F. Fiore; S. Pellegrini; G. Matt; L. A. Antonelli; A. Comastri; R. Della Ceca; E. Giallongo; S. Mathur; S. Molendi; A. Siemiginowska; G. Trinchieri; B. Wilkes
texts
eye 52
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BeppoSAX observed NGC4258 on December 1998, when its 2-10 keV luminosity was \~1E41 erg/s. 100% variability is observed in the 3-10 keV band on timescales of a half a day while 20% variability is observed on timescales of one hour. The nuclear component is visible above 2 keV only, being obscured by a column density of (9.5+/-1.2)E22 cm-2; this component is detected up to 70 keV with S/N>=3 and with the steep power law energy index of 1.11+/-0.14. Bremsstrahlung emission for the 2-70 keV...
Source: http://arxiv.org/abs/astro-ph/0102438v1
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63
Sep 18, 2013
09/13
by
M. Guainazzi; F. Fiore; E. Giallongo; A. Laor; M. Elvis; A. Siemiginowska
texts
eye 63
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We have monitored with the RXTE PCA the variability pattern of the 2-20 keV flux in four PG quasars (QSOs) from the Laor et al. (1994) sample. Six observations of each target at regular intervals of 1 day were performed. The sample comprises objects with extreme values of Balmer line width (and hence soft X-ray steepness) and spans about one order of magnitude in luminosity. The most robust result is that the variability amplitude decreases as energy increases. Several options for a possible...
Source: http://arxiv.org/abs/astro-ph/0005131v1
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42
Sep 19, 2013
09/13
by
M. Kunert-Bajraszewska; M. P. Gawronski; A. Labiano; A. Siemiginowska
texts
eye 42
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We present a new sample of Compact Steep Spectrum (CSS) sources with radio luminosity below 10^26 W/Hz at 1.4 GHz called the low luminosity compact (LLC) objects. The sources have been selected from FIRST survey and observed with MERLIN at L-band and C-band. The main criterion used for selection was luminosity of the objects and approximately one third of the CSS sources from the new sample have a value of radio luminosity comparable to FRIs. About 80% of the sources have been resolved and...
Source: http://arxiv.org/abs/1009.5235v1
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47
Sep 19, 2013
09/13
by
M. Kunert-Bajraszewska; A. Siemiginowska; K. Katarzynski; A. Janiuk
texts
eye 47
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We present new results on X-ray properties of radio loud broad absorption line (BAL) quasars and focus on broad-band spectral properties of a high ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We...
Source: http://arxiv.org/abs/0910.0579v2
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61
Sep 21, 2013
09/13
by
C. C. Cheung; L. Stawarz; A. Siemiginowska; D. E Harris; D. A. Schwartz; J. F. C. Wardle; D. Gobeille; N. P. Lee
texts
eye 61
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We describe our efforts to understand large-scale (10's-100's kpc) relativistic jet systems through observations of the highest-redshift quasars. Results from a VLA survey search for radio jets in ~30 z>3.4 quasars are described along with new Chandra observations of 4 selected targets.
Source: http://arxiv.org/abs/0712.1192v1
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45
Sep 19, 2013
09/13
by
D. A. Schwartz; D. E. Harris; H. Landt; A. Siemiginowska; E. S. Perlman; C. C. Cheung; J. M. Gelbord; D. M. Worrall; M. Birkinshaw; S. G. Jorstad; A. P. Marscher; L. Stawarz
texts
eye 45
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We investigate the variations of the magnetic field, Doppler factor, and relativistic particle density along the jet of a quasar at z=0.72. We chose 4C 19.44 for this study because of its length and straight morphology. The 18 arcsec length of the jet provides many independent resolution elements in the Chandra X-ray image. The straightness suggests that geometry factors, although uncertain, are almost constant along the jet. We assume the X-ray emission is from inverse Compton scattering of...
Source: http://arxiv.org/abs/astro-ph/0610755v1
4
4.0
Jun 28, 2018
06/18
by
M. J. Hardcastle; E. Lenc; M. Birkinshaw; J. H. Croston; J. L. Goodger; H. L. Marshall; E. S. Perlman; A. Siemiginowska; L. Stawarz; D. M. Worrall
texts
eye 4
favorite 0
comment 0
We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The new X-ray data have a factor 4 more exposure than observations previously presented and span a 15-year time baseline, allowing a detailed study of the spatial, temporal and spectral properties of the AGN, jet, hotspot and lobes. We present evidence for further time variation of the jet, though the flare that we reported in...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1510.08392
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37
Sep 19, 2013
09/13
by
M. Kunert-Bajraszewska; A. Janiuk; A. Siemiginowska; M. Gawronski
texts
eye 37
favorite 0
comment 0
We consider the radiation pressure instability operating on short timescales 10^3 - 10^6 years in the accretion disk around a supermassive black hole as the origin of the intermittent activity of radio sources. We test whether this instability can be responsible for short ages (
Source: http://arxiv.org/abs/1010.2762v1
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58
Jul 20, 2013
07/13
by
A. Comastri; F. Fiore; M. Guainazzi; G. Matt; G. M. Stirpe; G. Zamorani; W. N. Brandt; K. M. Leighly; L. Piro; S. Molendi; A. N. Parmar; A. Siemiginowska; E. M. Puchnarewicz
texts
eye 58
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We report on the first spectrum up to 10 keV of the bright narrow-line Seyfert 1 galaxy Ton S 180, obtained with the imaging instruments onboard BeppoSAX. This is the first observed source in a sample of a dozen narrow-line Seyfert 1 galaxies in the BeppoSAX Core Program. We also present and discuss a high quality optical spectrum taken at the 1.5 m telescope at La Silla two months before the BeppoSAX observation. The X-ray spectrum shows a clear hardening above about 2 keV, where a power law...
Source: http://arxiv.org/abs/astro-ph/9712182v1
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49
Sep 20, 2013
09/13
by
M. A. Sobolewska; A. Siemiginowska; P. T. Zycki
texts
eye 49
favorite 0
comment 0
We modeled the spectral energy distribution (SED) of high redshift radio quiet quasars (high-z RQQs). We computed spectra in a patchy corona geometry where an accretion disk extends to the last stable orbit and the Comptonizing active regions (hot clouds) are distributed above the disk. We explored the model parameter space to find theoretical parameters that give spectra with the optical/UV luminosity, the X-ray loudness, and the X-ray photon index compatible with those of high-z RQQs observed...
Source: http://arxiv.org/abs/astro-ph/0410206v1
3
3.0
Jun 28, 2018
06/18
by
L. Ostorero; R. Morganti; A. Diaferio; A. Siemiginowska; Ł. Stawarz; R. Moderski; A. Labiano
texts
eye 3
favorite 0
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With the Westerbork Synthesis Radio Telescope, we performed HI observations of a sample of known X-ray emitting Gigahertz-peaked-spectrum galaxies with compact-symmetric-object morphology (GPS/CSOs) that lacked an HI absorption detection. We combined radio and X-ray data of the full sample of X-ray emitting GPS/CSOs and found a significant, positive correlation between the column densities of the total and neutral hydrogen ($N_{\rm H}$ and $N_{\rm HI}$, respectively). Using a Bayesian approach,...
Topics: Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1511.01649
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42
Sep 18, 2013
09/13
by
M. Guainazzi; A. Siemiginowska; C. Stanghellini; P. Grandi; E. Piconcelli; C. Azibuke
texts
eye 42
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We present the first broadband X-ray observations of four Giga-Hertz Peaked Spectrum (GPS) radio galaxies at redshift 2 keV) X-rays. All sources were detected. Their radio-to-X-ray spectral energy distributions are similar, except for PKS0941-080, which is X-ray under-luminous by about two orders of magnitude. The comparison between the full sample of GPS galaxies with measurements in hard X-rays and a control sample of radio galaxies rules out intrinsic X-ray weakness as causing a lower...
Source: http://arxiv.org/abs/astro-ph/0509043v2
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42
Sep 19, 2013
09/13
by
F. Fiore; G. Matt; M. Cappi; M. Elvis; K. M. Leighly; F. Nicastro; L. Piro; A. Siemiginowska; B. J. Wilkes
texts
eye 42
favorite 0
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Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong FeII emission, large and fast X-ray variability, rather steep 2-10 keV spectrum. These intriguing objects have been suggested to be the analogs of Galactic black hole candidates in the high, soft state. We present here results from ASCA observations for two of these quasars: NAB0205+024 and PG1244+026. Both objects show similar variations (factor of about 2 in 10 ks), despite a factor of about ten...
Source: http://arxiv.org/abs/astro-ph/9804256v1
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48
Sep 20, 2013
09/13
by
M. J. Hardcastle; F. Massaro; D. E. Harris; S. A. Baum; S. Bianchi; M. Chiaberge; R. Morganti; C. P. O'Dea; A. Siemiginowska
texts
eye 48
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We present Chandra X-ray and VLA radio observations of the radio galaxy 3C305. The X-ray observations reveal the details of the previously known extended X-ray halo around the radio galaxy. We show using X-ray spectroscopy that the X-ray emission is consistent with being shock-heated material and can be modelled with standard collisional-ionization models, rather than being photoionized by the active nucleus. On this basis, we can make a self-consistent model in which the X-ray-emitting plasma...
Source: http://arxiv.org/abs/1205.0962v1
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49
Sep 18, 2013
09/13
by
J. Kataoka; L. Stawarz; D. E. Harris; A. Siemiginowska; M. Ostrowski; M. R. Swain; M. J. Hardcastle; J. L. Goodger; K. Iwasawa; P. G. Edwards
texts
eye 49
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We report X-ray imaging of the powerful FR-II radio galaxy 3C353 using the Chandra X-ray Observatory. 3C353's two 4"-wide and 2'-long jets allow us to study in detail the internal structure of the large-scale relativistic outflows at both radio and X-ray photon energies with the sub-arcsecond spatial resolution. In a 90 ks Chandra observation, we have detected X-ray emission from most radio structures in 3C353, including the nucleus, the jet and the counterjet, the terminal jet regions...
Source: http://arxiv.org/abs/0806.1260v1
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68
Sep 22, 2013
09/13
by
G. Lanzuisi; F. Civano; M. Elvis; M. Salvato; G. Hasinger; C. Vignali; G. Zamorani; T. Aldcroft; M. Brusa; A. Comastri; F. Fiore; A. Fruscione; R. Gilli; L. C. Ho; V. Mainieri; A. Merloni; A. Siemiginowska
texts
eye 68
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We present the X-ray spectral analysis of the 390 brightest extragalactic sources in the Chandra-COSMOS catalog, showing at least 70 net counts in the 0.5-7 keV band. This sample has a 100% completeness in optical-IR identification, with 75% of the sample having a spectroscopic redshift and 25% a photometric redshift. Our analysis allows us to accurately determine the intrinsic absorption, the broad band continuum shape ({\Gamma}) and intrinsic L(2-10) distributions, with an accuracy better...
Source: http://arxiv.org/abs/1302.1062v2
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43
Sep 20, 2013
09/13
by
B. Czerny; A. Siemiginowska; A. Janiuk; A. C. Gupta
texts
eye 43
favorite 0
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We select a sample of 10 radio-quiet quasars with confirmed intranight optical variability and with available X-ray data. We compare the variability properties and the broad band spectral constraints to the predictions of intranight variability by three models: (i) irradiation of an accretion disk by a variable X-ray flux (ii) an accretion disk instability (iii) the presence of a weak blazar component. We concluded that the third model, e.g. the blazar component model, is the most promising if...
Source: http://arxiv.org/abs/0802.4396v1
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50
Sep 21, 2013
09/13
by
E. M. Puchnarewicz; K. O. Mason; A. Siemiginowska
texts
eye 50
favorite 0
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We present UV spectroscopy of RE1034+396, taken with the Faint Object Spectrograph on the Hubble Space Telescope. With a spectral resolution of ~1-2A FWHM and a typical S/N of ~15 per diode, this is one of the first detailed UV spectra of an object in the narrow-line Seyfert 1 (NLS1) class. The spectrum probes the physics and kinematics of the high-ionization and coronal line gas, and the strength and form of the big blue bump component in the UV. We detect many emission lines, including Lyman...
Source: http://arxiv.org/abs/astro-ph/9711009v1
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43
Sep 20, 2013
09/13
by
M. G. Dainotti; M. Ostrowski; D. Harris; A. Siemiginowska; H. Siejkowski
texts
eye 43
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Relativistic jets propagating through an ambient medium must produce some observational effects along their side boundaries because of interactions across the large velocity gradient. One possible effect of such an interaction would be a sheared magnetic field structure at the jet boundaries, leading to a characteristic radio polarization pattern. As proposed by Ostrowski, another effect can come from the generation of a high energy cosmic ray component at the boundary, producing dynamic...
Source: http://arxiv.org/abs/1205.1612v1
3
3.0
Jun 30, 2018
06/18
by
L. Stawarz; A. Szostek; C. C. Cheung; A. Siemiginowska; D. Koziel-Wierzbowska; N. Werner; A. Simionescu; G. Madejski; M. C. Begelman; D. E. Harris; M. Ostrowski; K. Hagino
texts
eye 3
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[abridged] Here we present the analysis of multifrequency data gathered for the FRII radio galaxy PKS B1358-113, hosted in the brightest cluster galaxy of Abell 1836. The galaxy harbors one of the most massive black holes known to date and our analysis of the optical data reveals that this black hole is only weakly active. Based on new Chandra and XMM-Newton X-ray observations and archival radio data we derive the preferred range for the jet kinetic luminosity $\sim (0.5-3) \times 10^{45}$ erg...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1404.5703
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54
Sep 19, 2013
09/13
by
M. Jamrozy; C. Konar; D. J. Saikia; L. Stawarz; K. -H. Mack; A. Siemiginowska
texts
eye 54
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We present radio observations at frequencies ranging from 240 to 8460 MHz of the radio galaxy 4C29.30 (J0840+2949) using the Giant Metrewave Radio Telescope (GMRT), the Very Large Array (VLA) and the Effelsberg telescope. We report the existence of weak extended emission with an angular size of $\sim$520 arcsec (639 kpc) within which a compact edge-brightened double-lobed source with a size of 29 arcsec (36 kpc) is embedded. We determine the spectrum of the inner double from 240 to 8460 MHz and...
Source: http://arxiv.org/abs/astro-ph/0703723v1
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48
Sep 23, 2013
09/13
by
Olof Tengstrand; M. Guainazzi; A. Siemiginowska; N. Fonseca Bonilla; A. Labiano; D. M. Worrall; P. Grandi; E. Piconcelli
texts
eye 48
favorite 0
comment 0
This paper presents the X-ray properties of a flux- and volume-limited complete sample of 16 Giga-Hertz Peaked Spectrum (GPS) galaxies. This study addresses three basic questions in our understanding of the nature and evolution of GPS sources: a) What is the physical origin of the X-ray emission in GPS galaxies? b) What physical system is associated with the X-ray obscuration? c) What is the "endpoint" of the evolution of compact radio sources? We obtain a 100% (94%) detection...
Source: http://arxiv.org/abs/0903.2444v3
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46
Sep 22, 2013
09/13
by
A. Różańska; B. Czerny; A. Siemiginowska; A. -M. Dumont; T. Kawaguchi
texts
eye 46
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We present new interpretation of Ton S180 spectrum obtained by {\it Chandra} Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines and a few emission disk lines have been successfully fitted to the data. We have not found any significant edges accompanying line emission. We propose the interpretation of narrow lines consistent with the paper recently written by Krolik (2002), where warm absorber is strongly inhomogeneous. Such situation is possible in so called...
Source: http://arxiv.org/abs/astro-ph/0309430v1
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45
Sep 20, 2013
09/13
by
G. Fabbiano; A. Baldi; S. Pellegrini; A. Siemiginowska; M. Elvis; A. Zezas; J. McDowell
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eye 45
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We report the results of the {\it Chandra} ACIS-S observations of the elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (of $3.5 \times 10^7 M_{\odot}$), but does not show sign of AGN activity. A small, 8.5$^{\prime\prime}$ long ($\sim 1$ kpc at the galaxy's distance of 23 Mpc), S-shaped, jet-like feature centered on the nucleus is detected in the 38 ksec ACIS-S integrated exposure of this region. The luminosity of this feature is $L_X \sim 2.6 \times 10^{39} \rm ergs...
Source: http://arxiv.org/abs/astro-ph/0405358v1
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67
Sep 20, 2013
09/13
by
M. A. Sobolewska; A. Siemiginowska; P. T. Zycki
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eye 67
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Two families of models are currently considered to describe an accretion flow onto black holes and production of the observed X-ray radiation: (1) a standard cold accretion disk with a hot corona above it and (2) an outer truncated accretion disk with a hot semispherical inner flow. We compute spectra in the scenario with a hot inner flow surrounded by a truncated accretion disk covered by a hot corona and test the results on a sample of high redshift (z > 4) quasars observed with Chandra....
Source: http://arxiv.org/abs/astro-ph/0410204v1
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60
Sep 19, 2013
09/13
by
S. Pellegrini; A. Baldi; D. W. Kim; G. Fabbiano; R. Soria; A. Siemiginowska; M. Elvis
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eye 60
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The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821, hosting a central massive black hole but inactive at all wavelengths, was observed with Chandra for a total exposure of 230 ksec, to search for nuclear emission and gas available for accretion. Within its optical image, 41 sources were detected, with spectral properties typical of low mass X-ray binaries (LMXBs). The fractions of LMXBs in the field and in globular clusters were determined, together with their X-ray luminosity...
Source: http://arxiv.org/abs/astro-ph/0701639v2
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55
Sep 24, 2013
09/13
by
G. Migliori; A. Siemiginowska; A. Celotti
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eye 55
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We present the X-ray analysis of a deep ~200 ksec Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z=1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution (SED), adopting several scenarios for the jet emission. For the values of the...
Source: http://arxiv.org/abs/1202.3153v1
93
93
Sep 20, 2013
09/13
by
A. Baldi; G. Fabbiano; S. Pellegrini; A. Siemiginowska; M. Elvis; A. Zezas; J. C. McDowell
texts
eye 93
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We report the results of the Chandra ACIS-S observations of the elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (of 3.5x10^7 solar masses), but does not show sign of AGN activity. A small, 8.5" long (~1 kpc at the galaxy's distance of 23 Mpc), S-shaped, jet-like feature centered on the nucleus is detected in the 38 ksec ACIS-S integrated exposure of this region. The luminosity of this feature is L_X ~ 2.6 x 10^39 erg/s (0.3-10 keV), and its spectrum is hard...
Source: http://arxiv.org/abs/astro-ph/0410169v1
88
88
Jul 20, 2013
07/13
by
M. Cappi; P. Mazzotta; M. Elvis; D. J. Burke; A. Comastri; F. Fiore; W. Forman; A. Fruscione; P. Green; D. Harris; E. J. Hooper; C. Jones; J. S. Kaastra; E. Kellogg; S. Murray; B. McNamara; F. Nicastro; T. J. Ponman; E. M. Schlegel; A. Siemiginowska; H. Tananbaum; A. Vikhlinin; S. Virani; B. Wilkes
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eye 88
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We present results from a Chandra X-ray Observatory study of the field X-ray source populations in 4 different observations: two high-redshift (z~0.5) clusters of galaxies 3C295 and RXJ003033.2+261819; and two non-cluster fields with similar exposure time. Surprisingly, the 0.5-2 keV source surface densities (~900-1200 sources deg**-2 at a flux limit of 1.5x10**-15 erg cm**-2s**-1) measured in an ~8'x8' area surrounding each cluster exceed by a factor of ~2 the value expected on the basis of...
Source: http://arxiv.org/abs/astro-ph/0009199v1
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46
Sep 23, 2013
09/13
by
A. Siemiginowska; C. C. Cheung; S. LaMassa; D. Burke; T. L. Aldcroft; J. Bechtold; M. Elvis; D. M. Worrall
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eye 46
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We report the first significant detection of an X-ray cluster associated with a powerful (L(bol) ~1e47 erg/sec) radio-loud quasar at high redshift (z=1.06). Diffuse X-ray emission is detected out to ~120 kpc from the CSS quasar 3C 186. A strong Fe-line emission at the z(rest)=1.06 confirms its thermal nature. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by ~2-3 orders of magnitude. This provides direct observational evidence that the radio...
Source: http://arxiv.org/abs/astro-ph/0511464v1
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51
Sep 19, 2013
09/13
by
F. Nicastro; A. Fruscione; M. Elvis; A. Siemiginowska; F. Fiore; S. Bianchi
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eye 51
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Mkn 421 was observed by Chandra twice, on November 5, 1999 as part of the Chandra calibration program, with the ACIS-HETG configuration, and on May 29, 2000 following our Target Of Opportunity request aimed to catch the source in an ultra-high state, with both the ACIS-HETG and the HRC-LETG configurations. In this contribution we present and compare the two Chandra-MEG observations of Mkn 421, which lasted 26 and 19.6 ks respectively.
Source: http://arxiv.org/abs/astro-ph/0102455v1
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11
Jun 27, 2018
06/18
by
K. Hagino; L. Stawarz; A. Siemiginowska; C. C. Cheung; D. Koziel-Wierzbowska; A. Szostek; G. Madejski; D. E. Harris; A. Simionescu; T. Takahashi
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eye 11
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Here we analyze radio, optical, and X-ray data for a peculiar cluster Abell 578. This cluster is not fully relaxed and consists of two merging sub-systems. The brightest cluster galaxy, CGPG 0719.8+6704, is a pair of interacting ellipticals with projected separation $\sim$10 kpc, the brighter of which hosts the radio source 4C +67.13. The Fanaroff-Riley type-II radio morphology of 4C +67.13 is unusual for central radio galaxies in local Abell clusters. Our new optical spectroscopy revealed that...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1503.07244
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39
Sep 20, 2013
09/13
by
G. Fabbiano; M. Elvis; S. Markoff; A. Siemiginowska; S. Pellegrini; A. Zezas; F. Nicastro; G. Trinchieri; J. McDowell
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eye 39
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Chandra observations of the supermassive black hole in the nucleus of IC1459 show a weak [L_X=8x10(40)erg s(-1), 0.3-8keV], unabsorbed nuclear X-ray source, with a slope Gamma=1.88+/-0.09, and no strong Fe-K line at 6.4keV (EW$
Source: http://arxiv.org/abs/astro-ph/0301297v1
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46
Sep 21, 2013
09/13
by
L. Stawarz; F. Aharonian; J. Kataoka; M. Ostrowski; A. Siemiginowska; M. Sikora
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eye 46
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Stimulated by recent observations of a radio-to-X-ray synchrotron flare from HST-1, the innermost knot of the M 87 jet, as well as by a detection of a very high energy gamma-ray emission from M 87, we investigated the dynamics and multiwavelength emission of the HST-1 region. We study thermal pressure of the hot interstellar medium in M 87 and argue for a presence of a gaseous condensation in its central parts. Interaction of the jet with such a feature is likely to result in formation of a...
Source: http://arxiv.org/abs/astro-ph/0602220v2
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53
Sep 22, 2013
09/13
by
L. Stawarz; A. Siemiginowska; M. Ostrowski; M. Sikora
texts
eye 53
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Several low-power kiloparsec-scale jets in nearby radio galaxies are known for their synchrotron radiation extending up to optical and X-ray photon energies. Here we comment on high-energy gamma-ray emission of one particular object of this kind, i.e. the kiloparsec-scale jet of M 87 radio galaxy, resulting from comptonization of the starlight photon field of the host galaxy by the synchrotron-emitting jet electrons. In the analysis, we include relativistic bulk velocity of the jet, as well as...
Source: http://arxiv.org/abs/astro-ph/0501597v2
