3
3.0
Jun 28, 2018
06/18
by
V. Ramakrishnan; T. Hovatta; M. Tornikoski; K. Nilsson; E. Lindfors; M. Baloković; A. Lähteenmäki; R. Reinthal; L. Takalo
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eye 3
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In an attempt to constrain and understand the emission mechanism of gamma rays, we perform a cross-correlation analysis of 15 blazars using light curves in millimetre, optical and gamma rays. We use discrete correlation function and consider only correlations significant at 99 per cent level. A strong correlation was found between 37 and 95 GHz with a near-zero time delay in most of the sources, and ~1 month or longer in the rest. A similar result was obtained between the optical and gamma-ray...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.02654
6
6.0
Jun 29, 2018
06/18
by
H. Landt; M. J. Ward; M. Balokovic; D. Kynoch; T. Storchi-Bergmann; C. Boisson; C. Done; J. Schimoia; D. Stern
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eye 6
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Narrow-line Seyfert 1 galaxies have been identified by the Fermi Gamma-Ray Space Telescope as a rare class of gamma-ray emitting active galactic nuclei (AGN). The lowest-redshift candidate among them is the source 1H 0323+342. Here we present quasi-simultaneous Gemini near-infrared and Keck optical spectroscopy for it, from which we derive a black hole mass based on both the broad Balmer and Paschen emission lines. We supplement these observations with a NuSTAR X-ray spectrum taken about two...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1609.08002
4
4.0
Jun 30, 2018
06/18
by
L. Marcotulli; V. S. Paliya; M. Ajello; A. Kaur; D. H. Hartmann; D. Gasparrini; J. Greiner; A. Rau; P. Schady; M. Balokovic; D. Stern; G. Madejski
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eye 4
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The most powerful sources among the blazar family are MeV blazars. Often detected at $z>2$, they usually display high X- and \gm-ray luminosities, larger-than-average jet powers and black hole masses $\gtrsim 10^9 M_{\odot}$. In the present work we perform a multiwavelength study of three high redshift blazars: 3FGL J0325.5+2223 ($z=2.06$), 3FGL J0449.0+1121 ($z= 2.15$), and 3FGL J0453.2$-$2808 ($z=2.56$), analysing quasi simultaneous data from GROND, \swift-UVOT and XRT, \nustar, and...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1703.10657
20
20
Jun 26, 2018
06/18
by
T. Hovatta; M. Petropoulou; J. L. Richards; D. Giannios; K. Wiik; M. Baloković; A. Lähteenmäki; B. Lott; W. Max-Moerbeck; V. Ramakrishnan; A. C. S. Readhead
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eye 20
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In 2012 Markarian 421 underwent the largest flare ever observed in this blazar at radio frequencies. In the present study, we start exploring this unique event and compare it to a less extreme event in 2013. We use 15 GHz radio data obtained with the Owens Valley Radio Observatory 40-m telescope, 95 GHz millimeter data from the Combined Array for Research in Millimeter-Wave Astronomy, and GeV gamma-ray data from the Fermi Gamma-ray Space Telescope. The radio light curves during the flaring...
Topics: High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1501.07407
6
6.0
Jun 29, 2018
06/18
by
M. Brightman; A. Masini; D. R. Ballantyne; M. Baloković; W. N. Brandt; C. -T. Chen; A. Comastri; D. Farrah; P. Gandhi; F. A. Harrison; C. Ricci; D. Stern; D. J. Walton
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eye 6
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Due to their heavily obscured central engines, the growth rate of Compton-thick (CT) active galactic nuclei (AGN) is difficult to measure. A statistically significant correlation between the Eddington ratio, {\lambda}$_{Edd}$, and the X-ray power-law index, {\Gamma}, observed in unobscured AGN offers an estimate of their growth rate from X-ray spectroscopy (albeit with large scatter). However, since X-rays undergo reprocessing by Compton scattering and photoelectric absorption when the...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1606.09265
4
4.0
Jun 30, 2018
06/18
by
A. Zoghbi; E. M. Cackett; C. Reynolds; E. Kara; F. A. Harrison; A. C. Fabian; A. Lohfink; G. Matt; M. Balokovic; S. E. Boggs; F. E. Christensen; W. Craig; C. J. Hailey; D. Stern; W. W. Zhang
texts
eye 4
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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...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1405.3674
4
4.0
Jun 30, 2018
06/18
by
G. Matt; M. Balokovic; A. Marinucci; D. R. Ballantyne; S. E. Boggs; F. E. Christensen; A. Comastri; W. W. Craig; P. Gandhi; C. J. Hailey; F. A. Harrison; G. Madejski; K. K. Madsen; D. Stern; W. W. Zhang
texts
eye 4
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NuSTAR observed the bright Compton-thin, narrow line Seyfert 1 galaxy, NGC 5506, for about 56 ks. In agreement with past observations, the spectrum is well fit by a power law with Gamma~1.9, a distant reflection component and narrow ionized iron lines. A relativistically blurred reflection component is not required by the data. When an exponential high energy cutoff is added to the power law, a value of 720(+130,-190) keV (90% confidence level) is found. Even allowing for systematic...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1412.4541
15
15
Jun 27, 2018
06/18
by
G. Tagliaferri; G. Ghisellini; M. Perri; M. Hayashida; M. Balokovic; S. Covino; P. Giommi; G. M. Madejski; S. Puccetti; T. Sbarrato; S. E. Boggs; J. Chiang; F. E. Christensen; W. W. Craig; C. J. Hailey; F. A. Harrison; D. Stern; W. W. Zhang
texts
eye 15
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The most powerful blazars are the flat spectrum radio quasars whose emission is dominated by a Compton component peaking between a few hundred keV and a few hundred MeV. We selected two bright blazars, PKS 2149-306 at redshift z=2.345 and S5 0836+710 at z=2.172, in order to observe them in the hard X-ray band with the NuSTAR satellite. In this band the Compton component is rapidly rising almost up to the peak of the emission. Simultaneous soft-X-rays and UV-optical observations were performed...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1503.04848
7
7.0
Jun 28, 2018
06/18
by
E. Rivers; M. Baloković; P. Arévalo; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; F. Harrison; M. Koss; C. Ricci; D. Stern; D. J. Walton; W. W. Zhang
texts
eye 7
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NGC 7582 is a well-studied X-ray bright Seyfert 2 with moderately heavy ($N_{\text{H}}\sim10^{23}-10^{24}$~cm$^{-2}$), highly variable absorption and strong reflection spectral features. The spectral shape changed around the year 2000, dropping in observed flux and becoming much more highly absorbed. Two scenarios have been put forth to explain this spectral change: 1) the central X-ray source partially ``shut off'' around this time, decreasing in intrinsic luminosity, with a delayed decrease...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.01951
8
8.0
Jun 28, 2018
06/18
by
A. Marinucci; S. Bianchi; G. Matt; D. M. Alexander; M. Balokovic; F. E. Bauer; W. N. Brandt; P. Gandhi; M. Guainazzi; F. A. Harrison; K. Iwasawa; M. Koss; K. K. Madsen; F. Nicastro; S. Puccetti; C. Ricci; D. Stern; D. J. Walton
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eye 8
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We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During the August 2014 observation, we detect with NuSTAR a flux excess above 20 keV ($32\pm6 \%$) with respect to the December 2012 observation and to a later observation performed in February 2015. We do not detect any spectral variation below 10 keV in the XMM-Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.03503
6
6.0
Jun 30, 2018
06/18
by
A. Marinucci; G. Matt; S. Bianchi; T. N. Lu; P. Arevalo; M. Baloković; D. Ballantyne; F. E. Bauer; S. E. Boggs; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; F. Harrison; S. Puccetti; E. Rivers; D. J. Walton; D. Stern; W. Zhang
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eye 6
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We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suzaku, BeppoSAX, Chandra and Swift. Simultaneous NuSTAR and Swift broad band spectra (in the 3-80 keV range) indicate a cutoff energy $E_{\rm c}>210$ keV, with no detectable contribution from Compton...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1411.5151
10
10.0
Jun 27, 2018
06/18
by
Michael J. Koss; C. Romero-Canizales; L. Baronchelli; S. H. Teng; M. Balokovic; S. Puccetti; F. E. Bauer; P. Arevalo; R. Assef; D. R. Ballantyne; W. N. Brandt; M. Brightman; A. Comastri; P. Gandhi; F. A. Harrison; B. Luo; K. Schawinski; D. Stern; E. Treister
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eye 10
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We present new NuSTAR and Chandra observations of NGC 3393, a galaxy reported to host the smallest separation dual AGN resolved in the X-rays. While past results suggested a 150 pc separation dual AGN, three times deeper Chandra imaging, combined with adaptive optics and radio imaging suggest a single, heavily obscured, radio-bright AGN. Using VLA and VLBA data, we find an AGN with a two-sided jet rather than a dual AGN and that the hard X-ray, UV, optical, NIR, and radio emission are all from...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1505.03524
4
4.0
Jun 30, 2018
06/18
by
D. R. Ballantyne; J. M. Bollenbacher; L. W. Brenneman; K. K. Madsen; M. Balokovic; S. E. Boggs; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; F. A. Harrison; A. M. Lohfink; A. Marinucci; C. B. Markwardt; D. Stern; D. J. Walton; W. W. Zhang
texts
eye 4
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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...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1408.5281
5
5.0
Jun 30, 2018
06/18
by
M. Baloković; G. Matt; F. A. Harrison; A. Zoghbi; D. R. Ballantyne; S. E. Boggs; F. E. Christensen; W. W. Craig; C. J. Esmerian; A. C. Fabian; F. Fürst; C. J. Hailey; A. Marinucci; M. L. Parker; C. S. Reynolds; D. Stern; D. J. Walton; W. W. Zhang
texts
eye 5
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Measurements of the high-energy cut-off in the coronal continuum of active galactic nuclei have long been elusive for all but a small number of the brightest examples. We present a direct measurement of the cut-off energy in the nuclear continuum of the nearby Seyfert 1.9 galaxy MCG -05-23-016 with unprecedented precision. The high sensitivity of NuSTAR up to 79 keV allows us to clearly disentangle the spectral curvature of the primary continuum from that of its reflection component. Using a...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1412.5978
4
4.0
Jun 29, 2018
06/18
by
Michael J. Koss; R. Assef; M. Balokovic; D. Stern; P. Gandhi; I. Lamperti; D. M. Alexander; D. R. Ballantyne; F. E. Bauer; S. Berney; W. N. Brandt; A. Comastri; N. Gehrels; F. A. Harrison; G. Lansbury; C. Markwardt; C. Ricci; E. Rivers; K. Schawinski; E. Treister; C. Megan Urry
texts
eye 4
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We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick AGN in low-quality Swift BAT X-ray data. Using NuSTAR, we observe nine high SC-selected AGN. We find that high-sensitivity spectra show the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (NH~5-8x10^23 cm^-2). We find the SC_bat and SC_nustar measurements are consistent, suggesting this technique can be applied to future telescopes. We tested the SC method...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1604.07825
4
4.0
Jun 29, 2018
06/18
by
A. Masini; A. Comastri; M. Baloković; I. Zaw; S. Puccetti; D. R. Ballantyne; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; F. A. Harrison; M. J. Koss; G. Madejski; C. Ricci; E. Rivers; D. Stern; W. W. Zhang
texts
eye 4
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Aims. Study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser Active Galactic Nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with available physical quantities from VLBI mapping. Results. Most of the sources analyzed are heavily...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1602.03185
4
4.0
Jun 29, 2018
06/18
by
A. Masini; A. Comastri; S. Puccetti; M. Baloković; P. Gandhi; M. Guainazzi; F. E. Bauer; S. E. Boggs; P. G. Boorman; M. Brightman; F. E. Christensen; W. W. Craig; D. Farrah; C. J. Hailey; F. A. Harrison; M. J. Koss; S. M. LaMassa; C. Ricci; D. Stern; D. J. Walton; W. W. Zhang
texts
eye 4
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Aims. We study the long-term variability of the well-known Seyfert 2 galaxy Mrk 1210 (a.k.a. UGC 4203, or the Phoenix galaxy). Methods. The source was observed by many X-ray facilities in the last 20 years. Here we present a NuSTAR observation and put the results in context of previously published observations. Results. NuSTAR observed Mrk 1210 in 2012 for 15.4 ks. The source showed Compton-thin obscuration similar to that observed by Chandra, Suzaku, BeppoSAX and XMM-Newton over the past two...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1609.00374
13
13
Jun 26, 2018
06/18
by
M. Brightman; M. Balokovic; D. Stern; P. Arevalo; D. R. Ballantyne; F. E. Bauer; S. E. Boggs; W. W. Craig; F. E. Christensen; A. Comastri; F. Fuerst; P. Gandhi; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. LaMassa; S. Puccetti; E. Rivers; R. Vasudevan; D. J. Walton; W. W. Zhang
texts
eye 13
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The covering factor of Compton-thick obscuring material associated with the torus in active galactic nuclei (AGN) is at present best understood through the fraction of sources exhibiting Compton-thick absorption along the line of sight ($N_{H}>1.5\times10^{24}$ cm$^{-2}$) in the X-ray band, which reveals the average covering factor. Determining this Compton-thick fraction is difficult however, due to the extreme obscuration. With its spectral coverage at hard X-rays ($>$10 keV), NuSTAR is...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1502.07353
5
5.0
Jun 29, 2018
06/18
by
D. Blinov; V. Pavlidou; I. Papadakis; S. Kiehlmann; I. Liodakis; G. V. Panopoulou; T. J. Pearson; E. Angelakis; M. Baloković; T. Hovatta; V. Joshi; O. G. King; A. Kus; N. Kylafis; A. Mahabal; A. Marecki; I. Myserlis; E. Paleologou; I. Papamastorakis; E. Pazderski; S. Prabhudesai; A. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; J. A. Zensus
texts
eye 5
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We present a new set of optical polarization plane rotations in blazars, observed during the third year of operation of RoboPol. The entire set of rotation events discovered during three years of observations is analysed with the aim of determining whether these events are inherent in all blazars. It is found that the frequency of the polarization plane rotations varies widely among blazars. This variation cannot be explained either by a difference in the relativistic boosting or by selection...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1607.04292
3
3.0
Jun 30, 2018
06/18
by
A. Marinucci; G. Matt; E. Kara; G. Miniutti; M. Elvis; P. Arevalo; D. R. Ballantyne; M. Balokovic; F. Bauer; L. Brenneman; S. E. Boggs; M. Cappi; F. E. Christensen; W. W. Craig; A. C. Fabian; F. Fuerst; C. J. Hailey; F. A. Harrison; G. Risaliti; C. S. Reynolds; D. K. Stern; D. J. Walton; W. Zhang
texts
eye 3
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We present a broad band spectral analysis of the joint XMM-Newton and NuSTAR observational campaign of the Narrow Line Seyfert 1 SWIFT J2127.4+5654, consisting of 300 ks performed during three XMM-Newton orbits. We detect a relativistic broadened iron K$\alpha$ line originating from the innermost regions of the accretion disc surrounding the central black hole, from which we infer an intermediate spin of $a$=$0.58^{+0.11}_{-0.17}$. The intrinsic spectrum is steep ($\Gamma=2.08\pm0.01$) as...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1402.7245
7
7.0
Jun 30, 2018
06/18
by
O. G. King; D. Blinov; D. Giannios; I. Papadakis; E. Angelakis; M. Balokovic; L. Fuhrmann; T. Hovatta; P. Khodade; S. Kiehlmann; N. Kylafis; A. Kus; I. Myserlis; D. Modi; G. Panopoulou; I. Papamastorakis; V. Pavlidou; B. Pazderska; E. Pazderski; T. J. Pearson; C. Rajarshi; A. N. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; J. A. Zensus
texts
eye 7
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We report the polarized optical light curve of a gamma-ray burst afterglow obtained using the RoboPol instrument. Observations began 655 seconds after the initial burst of gamma-rays from GRB131030A, and continued uninterrupted for 2 hours. The afterglow displayed a low, constant fractional linear polarization of $p = (2.1 \pm 1.6)\,\%$ throughout, which is similar to the interstellar polarization measured on nearby stars. The optical brightness decay is consistent with a forward-shock...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1409.2417
49
49
Jun 27, 2018
06/18
by
D. Blinov; V. Pavlidou; I. Papadakis; S. Kiehlmann; G. Panopoulou; I. Liodakis; O. G. King; E. Angelakis; M. Baloković; H. Das; R. Feiler; L. Fuhrmann; T. Hovatta; P. Khodade; A. Kus; N. Kylafis; I. Myserlis; D. Modi; B. Pazderska; E. Pazderski; I. Papamastorakis; T. J. Pearson; C. Rajarshi; A. Ramaprakash; P. Reig; A. C. S. Readhead; K. Tassis; J. A. Zensus
texts
eye 49
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We present first results on polarization swings in optical emission of blazars obtained by RoboPol, a monitoring program of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events. A possible connection of polarization swing events with periods of high activity in gamma rays is investigated using the dataset obtained during the first season of operation. It was found that the brightest gamma-ray flares tend to be located closer in time to...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1505.07467
4
4.0
Jun 29, 2018
06/18
by
E. Angelakis; T. Hovatta; D. Blinov; V. Pavlidou; S. Kiehlmann; I. Myserlis; M. Boettcher; P. Mao; G. V. Panopoulou; I. Liodakis; O. G. King; M. Balokovic; A. Kus; N. Kylafis; A. Mahabal; A. Marecki; E. Paleologou; I. Papadakis; I. Papamastorakis; E. Pazderski; T. J. Pearson; S. Prabhudesai; A. N. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; M. Urry; J. A. Zensus
texts
eye 4
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We present average R-band optopolarimetric data, as well as variability parameters, from the first and second RoboPol observing season. We investigate whether gamma- ray--loud and gamma-ray--quiet blazars exhibit systematic differences in their optical polarization properties. We find that gamma-ray--loud blazars have a systematically higher polarization fraction (0.092) than gamma-ray--quiet blazars (0.031), with the hypothesis of the two samples being drawn from the same distribution of...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1609.00640
13
13
Jun 27, 2018
06/18
by
G. V. Panopoulou; K. Tassis; D. Blinov; V. Pavlidou; O. G. King; E. Paleologou; A. Ramaprakash; E. Angelakis; M. Balokovic; H. K. Das; R. Feiler; T. Hovatta; P. Khodade; S. Kiehlmann; A. Kus; N. Kylafis; I. Liodakis; A. Mahabal; D. Modi; I. Myserlis; I. Papadakis; I. Papamastorakis; B. Pazderska; E. Pazderski; T. J. Pearson; C. Rajarshi; A. C. S. Readhead; P. Reig; J. A. Zensus
texts
eye 13
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The stages before the formation of stars in molecular clouds are poorly understood. Insights can be gained by studying the properties of quiescent clouds, such as their magnetic field structure. The plane-of-the-sky orientation of the field can be traced by polarized starlight. We present the first extended, wide-field ($\sim$10 $\rm deg^2$) map of the Polaris Flare cloud in dust-absorption induced optical polarization of background stars, using the RoboPol polarimeter at the Skinakas...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1503.03054
6
6.0
Jun 29, 2018
06/18
by
D. Blinov; V. Pavlidou; I. E. Papadakis; T. Hovatta; T. J. Pearson; I. Liodakis; G. V. Panopoulou; E. Angelakis; M. Baloković; H. Das; P. Khodade; S. Kiehlmann; O. G. King; A. Kus; N. Kylafis; A. Mahabal; A. Marecki; D. Modi; I. Myserlis; E. Paleologou; I. Papamastorakis; B. Pazderska; E. Pazderski; C. Rajarshi; A. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; J. A. Zensus
texts
eye 6
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We present measurements of rotations of the optical polarization of blazars during the second year of operation of RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events, and we analyse the large set of rotation events discovered in two years of observation. We investigate patterns of variability in the polarization parameters and total flux density during the rotation events and compare them to the behaviour...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1601.03392
20
20
Jun 28, 2018
06/18
by
A. Annuar; P. Gandhi; D. M. Alexander; G. B. Lansbury; P. Arévalo; D. R. Ballantyne; M. Baloković; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; A. Del Moro; C. J. Hailey; F. A. Harrison; R. C. Hickox; G. Matt; S. Puccetti; C. Ricci; J. R. Rigby; D. Stern; D. J. Walton; L. Zappacosta; W. Zhang
texts
eye 20
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We present two NuSTAR observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy ($\sim$0.5-100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line-of-sight. However, the lack of...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1509.03322
6
6.0
Jun 28, 2018
06/18
by
S. Puccetti; A. Comastri; F. E. Bauer; W. N. Brandt; F. Fiore; F. A. Harrison; B. Luo; D. Stern; C. M. Urry; D. M. Alexander; A. Annuar; P. Arévalo; M. Baloković; S. E. Boggs; M. Brightman; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; M. J. Koss; S. La Massa; A. Marinucci; C. Ricci; D. J. Walton; L. Zappacosta; W. Zhang
texts
eye 6
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We present a broad-band (~0.3-70 keV) spectral and temporal analysis of NuSTAR observations of the luminous infrared galaxy NGC 6240, combined with archival Chandra, XMM-Newton and BeppoSAX data. NGC 6240 is a galaxy in a relatively early merger state with two distinct nuclei separated by ~1."5. Previous Chandra observations have resolved the two nuclei, showing that they are both active and obscured by Compton-thick material. Although they cannot be resolved by NuSTAR, thanks to the...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1510.04477
6
6.0
Jun 28, 2018
06/18
by
F. Fuerst; C. Mueller; K. K. Madsen; L. Lanz; E. Rivers; M. Brightman; P. Arevalo; M. Balokovic; T. Beuchert; S. E. Boggs; F. E. Christensen; W. W. Craig; T. Dauser; D. Farrah; C. Graefe; C. J. Hailey; F. A. Harrison; M. Kadler; A. King; F. Krauss; G. Madejski; G. Matt; A. Marinucci; A. Markowitz; P. Ogle; R. Ojha; R. Rothschild; D. Stern; D. J. Walton; J. Wilms; W. Zhang
texts
eye 6
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We present simultaneous XMM-Newton and NuSTAR observations spanning 3-78 keV of the nearest radio galaxy, Centaurus A (Cen A). The accretion geometry around the central engine in Cen A is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the central region of Cen A with sub-arcminute resolution at X-ray energies above 10 keV for the first time, but finds no evidence for an extended source or other off-nuclear point-sources. The...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.01915
9
9.0
Jun 30, 2018
06/18
by
G. B. Lansbury; D. M. Alexander; A. Del Moro; P. Gandhi; R. J. Assef; D. Stern; J. Aird; D. R. Ballantyne; M. Balokovic; F. E. Bauer; S. E. Boggs; W. N. Brandt; F. E. Christensen; W. W. Craig; M. Elvis; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. M. LaMassa; B. Luo; J. R. Mullaney; S. H. Teng; C. M. Urry; W. W. Zhang
texts
eye 9
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We present NuSTAR hard X-ray (3-79 keV) observations of three Type 2 quasars at z ~ 0.4-0.5, optically selected from the Sloan Digital Sky Survey (SDSS). Although the quasars show evidence for being heavily obscured Compton-thick systems on the basis of the 2-10 keV to [OIII] luminosity ratio and multiwavelength diagnostics, their X-ray absorbing column densities (N_H) are poorly known. In this analysis: (1) we study X-ray emission at >10 keV, where X-rays from the central black hole are...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1402.2666
7
7.0
Jun 30, 2018
06/18
by
A. Del Moro; J. R. Mullaney; D. M. Alexander; A. Comastri; F. E. Bauer; E. Treister; D. Stern; F. Civano; P. Ranalli; C. Vignali; J. A. Aird; D. R. Ballantyne; M. Baloković; S. E. Boggs; W. N. Brandt; F. E. Christensen; W. W. Craig; P. Gandhi; R. Gilli; C. J. Hailey; F. A. Harrison; R. C. Hickox; S. M. LaMassa; G. B. Lansbury; B. Luo; S. Puccetti; M. Urry; W. W. Zhang
texts
eye 7
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We report NuSTAR observations of NuSTAR J033202-2746.8, a heavily obscured, radio-loud quasar detected in the Extended Chandra Deep Field-South, the deepest layer of the NuSTAR extragalactic survey (~400 ks, at its deepest). NuSTAR J033202-2746.8 is reliably detected by NuSTAR only at E>8 keV and has a very flat spectral slope in the NuSTAR energy band (Gamma=0.55^{+0.62}_{-0.64}; 3-30 keV). Combining the NuSTAR data with extremely deep observations by Chandra and XMM-Newton (4 Ms and 3 Ms,...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1403.2491
5
5.0
Jun 30, 2018
06/18
by
M. Baloković; A. Comastri; F. A. Harrison; D. M. Alexander; D. R. Ballantyne; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; A. Del Moro; P. Gandhi; C. J. Hailey; M. Koss; G. B. Lansbury; B. Luo; G. M. Madejski; A. Marinucci; G. Matt; C. B. Markwardt; S. Puccetti; C. S. Reynolds; G. Risaliti; E. Rivers; D. Stern; D. J. Walton; W. W. Zhang
texts
eye 5
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We present X-ray spectral analyses for three Seyfert 2 active galactic nuclei, NGC 424, NGC 1320, and IC 2560, observed by NuSTAR in the 3-79 keV band. The high quality hard X-ray spectra allow detailed modeling of the Compton reflection component for the first time in these sources. Using quasi-simultaneous NuSTAR and Swift/XRT data, as well as archival XMM-Newton data, we find that all three nuclei are obscured by Compton-thick material with column densities in excess of ~5 x $10^{24}$...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1408.5414
16
16
Jun 28, 2018
06/18
by
G. B. Lansbury; P. Gandhi; D. M. Alexander; R. J. Assef; J. Aird; A. Annuar; D. R. Ballantyne; M. Balokovic; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; F. Civano; A. Comastri; W. W. Craig; A. Del Moro; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. M. LaMassa; B. Luo; S. Puccetti; D. Stern; E. Treister; C. Vignali; L. Zappacosta; W. W. Zhang
texts
eye 16
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The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end of the quasar population and for redshifts z 1.5e24 cm^-2) type 2 quasars (CTQSO2s); five new NuSTAR observations are reported herein, and four have been previously published. The candidate CTQSO2s lie at z ~ 90 net source counts at 8-24 keV). For these NuSTAR-detected sources direct (i.e., X-ray spectral) constraints on the intrinsic AGN properties are feasible, and we measure column...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1506.05120
8
8.0
Jun 30, 2018
06/18
by
P. Gandhi; G. B. Lansbury; D. M. Alexander; D. Stern; P. Arévalo; D. R. Ballantyne; M. Baloković; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; M. Elvis; A. C. Fabian; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. M. LaMassa; B. Luo; G. M. Madejski; A. F. Ptak; S. Puccetti; S. H. Teng; C. M. Urry; D. J. Walton; W. W. Zhang
texts
eye 8
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We present Nustar 3-40 keV observations of the optically selected Type 2 quasar (QSO2) SDSS J1034+6001 or Mrk 34. The high-quality hard X-ray spectrum and archival XMM-Newton data can be fitted self-consistently with a reflection-dominated continuum and strong Fe Kalpha fluorescence line with equivalent-width >1 keV. Prior X-ray spectral fitting below 10 keV showed the source to be consistent with being obscured by Compton-thin column densities of gas along the line-of-sight, despite...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics, Cosmology and...
Source: http://arxiv.org/abs/1407.1844
7
7.0
Jun 30, 2018
06/18
by
D. Stern; G. B. Lansbury; R. J. Assef; W. N. Brandt; D. M. Alexander; D. R. Ballantyne; M. Balokovic; D. Benford; A. Blain; S. E. Boggs; C. Bridge; M. Brightman; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; P. R. M. Eisenhardt; P. Gandhi; R. Griffith; C. J. Hailey; F. A. Harrison; R. C. Hickox; T. H. Jarrett; M. Koss; S. Lake; S. M. LaMassa; B. Luo; C. -W. Tsai; D. J. Walton; E. L. Wright; J. Wu; L. Yan; W. W. Zhang
texts
eye 7
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We report on a NuSTAR and XMM-Newton program that has observed a sample of three extremely luminous, heavily obscured WISE-selected AGN at z~2 in a broad X-ray band (0.1 - 79 keV). The parent sample, selected to be faint or undetected in the WISE 3.4um (W1) and 4.6um (W2) bands but bright at 12um (W3) and 22um (W4), are extremely rare, with only ~1000 so-called W1W2-dropouts across the extragalactic sky. Optical spectroscopy reveals typical redshifts of z~2 for this population, implying...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1403.3078
4
4.0
Jun 29, 2018
06/18
by
E. Bañados; B. P. Venemans; R. Decarli; E. P. Farina; C. Mazzucchelli; F. Walter; X. Fan; D. Stern; E. Schlafly; K. C. Chambers; H-W. Rix; L. Jiang; I. McGreer; R. Simcoe; F. Wang; J. Yang; E. Morganson; G. De Rosa; J. Greiner; M. Baloković; W. S. Burgett; T. Cooper; P. W. Draper; H. Flewelling; K. W. Hodapp; H. D. Jun; N. Kaiser; R. -P. Kudritzki; E. A. Magnier; N. Metcalfe; D. Miller; J. -T. Schindler; J. L. Tonry; R. J. Wainscoat; C. Waters; Q. Yang
texts
eye 4
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Luminous quasars at z>5.6 can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe. Thus far these studies have been statistically limited by the number of quasars known at these redshifts. Such quasars are rare and therefore wide-field surveys are required to identify them and multiwavelength data are needed to separate them efficiently from their main contaminants, the far more numerous cool dwarfs. In...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1608.03279
14
14
Jun 28, 2018
06/18
by
J. R. Mullaney; A. Del-Moro; J. Aird; D. M. Alexander; F. M. Civano; R. C. Hickox; G. B. Lansbury; M. Ajello; R. Assef; D. R. Ballantyne; M. Balokovic; F. E. Bauer; W. N. Brandt; S. E. Boggs; M. Brightman; F. E. Christensen; A. Comastri; W. W. Craig; M. Elvis; K. Forster; P. Gandhi; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; M. Koss; S. M. LaMassa; B. Luo; K. K. Madsen; S. Puccetti; C. Saez; D. Stern; E. Treister; C. M. Urry; D. R. Wik; L. Zappacosta; W. Zhang
texts
eye 14
favorite 1
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We present initial results and the source catalog from the NuSTAR survey of the Extended Chandra Deep Field South (hereafter, ECDFS) - currently the deepest contiguous component of the NuSTAR extragalactic survey program. The survey covers the full ~30 arcmin x 30 arcmin area of this field to a maximum depth of ~360 ks (~220 ks when corrected for vignetting at 3-24 keV), reaching sensitivity limits of ~1.3 x 10^-14 erg/cm2/s (3-8 keV), ~3.4 x 10^-14 erg/cm2/s (8-24 keV) and ~3.0 x 10^-14...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04186
3
3.0
Jun 29, 2018
06/18
by
G. B. Lansbury; D. Stern; J. Aird; D. M. Alexander; C. Fuentes; F. A. Harrison; E. Treister; F. E. Bauer; J. A. Tomsick; M. Balokovic; A. Del Moro; P. Gandhi; M. Ajello; A. Annuar; D. R. Ballantyne; S. E. Boggs; N. Brandt; M. Brightman; C. J. Chen; F. E. Christensen; F. Civano; A. Comastri; W. W. Craig; K. Forster; B. W. Grefenstette; C. J. Hailey; R. Hickox; B. Jiang; H. Jun; M. Koss; S. Marchesi; A. D. Melo; J. R. Mullaney; G. Noirot; S. Schulze; D. J. Walton; L. Zappacosta; W. Zhang
texts
eye 3
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We present the first full catalog and science results for the NuSTAR serendipitous survey. The catalog incorporates data taken during the first 40 months of NuSTAR operation, which provide ~20Ms of effective exposure time over 331 fields, with an areal coverage of 13 sq deg, and 497 sources detected in total over the 3-24 keV energy range. There are 276 sources with spectroscopic redshifts and classifications, largely resulting from our extensive campaign of ground-based spectroscopic followup....
Topics: Astrophysics, High Energy Astrophysical Phenomena, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1612.06389
10
10.0
Jun 28, 2018
06/18
by
J. Aird; D. M. Alexander; D. R. Ballantyne; F. Civano; A. Del-Moro; R. C. Hickox; G. B. Lansbury; J. R. Mullaney; F. E. Bauer; W. N. Brandt; A. Comastri; A. C. Fabian; P. Gandhi; F. A. Harrison; B. Luo; D. Stern; E. Treister; L. Zappacosta; M. Ajello; R. Assef; S. E. Boggs; M. Brightman; F. E. Christensen; W. W. Craig; M. Elvis; K. Forster; M. Balokovic; B. W. Grefenstette; C. J. Hailey; M. Koss; S. M. LaMassa; K. K. Madsen; S. Puccetti; C. Saez; C. M. Urry; D. R. Wik; W. Zhang
texts
eye 10
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We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of Active Galactic Nuclei (AGNs) based on a sample of 94 sources at 0.1 < z
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04184
7
7.0
Jun 29, 2018
06/18
by
G. M. Madejski; K. Nalewajko; K. K. Madsen; J. Chiang; M. Baloković; D. Paneque; A. K. Furniss; M. Hayashida; C. M. Urry; M. Sikora; M. Ajello; R. D. Blandford; F. A. Harrison; D. Sanchez; B. Giebels; D. Stern; D. M. Alexander; D. Barret; S. E. Boggs; F. E. Christensen; W. W. Craig; K. Forster; P. Giommi; B. Grefenstette; C. Hailey; A. Hornstrup; T. Kitaguchi; J. E. Koglin; P. H. Mao; H. Miyasaka; K. Mori; M. Perri; M. J. Pivovaroff; S. Puccetti; V. Rana; N. J. Westergaard; W. W. Zhang; A....
texts
eye 7
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We report the first hard X-ray observations with NuSTAR of the BL Lac type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and gamma-ray data from the Fermi Large Area Telescope, obtained in April 2013 when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5 - 60 keV, is best described by a model consisting of a log-parabola component with curvature beta = 0.3(+0.2,-0.1) and a (local) photon index 3.04 +/- 0.15 at photon...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1609.02203
9
9.0
Jun 28, 2018
06/18
by
F. A. Harrison; J. Aird; F. Civano; G. Lansbury; J. R. Mullaney; D. R. Ballantyne; D. M. Alexander; D. Stern; M. Ajello; D. Barret; F. E. Bauer; M. Balokovic; W. N. Brandt; M. Brightman; S. E. Boggs; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; K. Forster; P. Gandhi; P. Giommi; B. W. Grefenstette; C. J. Hailey; R. C. Hickox; A. Hornstrup; T. Kitaguchi; J. Koglin; B. Luo; K. K. Madsen; P. H. Mao; H. Miyasaka; K. Mori; M. Perri; M. Pivovaroff; S. Puccetti; V. Rana; E. Treister; D....
texts
eye 9
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We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGN) identified in the NuSTAR extragalactic surveys. NuSTAR has now resolved 33-39% of the X-ray background in the 8-24 keV band, directly identifying AGN with obscuring columns up to approximately 1e25 /cm2. In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range 5e-15 < S(3 - 8 keV)/(erg/cm2/s) < 1e-12 probed by NuSTAR. In the hard...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04183
18
18
Jun 26, 2018
06/18
by
M. Hayashida; K. Nalewajko; G. M. Madejski; M. Sikora; R. Itoh; M. Ajello; R. D. Blandford; S. Buson; J. Chiang; Y. Fukazawa; A. K. Furniss; C. M. Urry; I. Hasan; F. A. Harrison; D. M. Alexander; M. Baloković; D. Barret; S. E. Boggs; F. E. Christensen; W. W. Craig; K. Forster; P. Giommi; B. Grefenstette; C. Hailey; A. Hornstrup; T. Kitaguchi; J. E. Koglin; K. K. Madsen; P. H. Mao; H. Miyasaka; K. Mori; M. Perri; M. J. Pivovaroff; S. Puccetti; V. Rana; D. Stern; G. Tagliaferri; N. J....
texts
eye 18
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We report the results of a multi-band observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The $\gamma$-ray emission of the source measured by Fermi-LAT showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the Fermi mission, with $F(E > 100\,{\rm MeV})$ of $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and with a flux...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1502.04699
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15
Jun 29, 2018
06/18
by
A. U. Abeysekara; S. Archambault; A. Archer; W. Benbow; R. Bird; M. Buchovecky; J. H. Buckley; V. Bugaev; J. V Cardenzana; M. Cerruti; X. Chen; B. De Lotto; E. de Oña Wilhelmi; F. Di Pierro; M. Doert; A. Domínguez; D. Dominis Prester; D. Dorner; M. Doro; S. Einecke; D. Eisenacher Glawion; L. Ciupik; D. Elsaesser; M. Engelkemeier; V. Fallah Ramazani; A. Fernández-Barral; D. Fidalgo; M. V. Fonseca; L. Font; C. Fruck; D. Galindo; R. J. García López; M. P. Connolly; M. Garczarczyk; M. Gaug; P....
texts
eye 15
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Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three "target-of-opportunity" (ToO) observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1611.04626
