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We performed an observational program with the X-ray satellite BeppoSAX to study objects with extreme synchrotron peak frequencies (nu_peak > 1 keV). Of the seven sources observed, four showed peak frequencies in the range 1-5 keV, while…

Recent observations have shown that in many large solar energetic particle (SEP) events the event-integrated differential spectra resemble double power laws. We perform numerical modeling of particle acceleration at coronal shocks…

Solar and Stellar Astrophysics · Physics 2022-02-16 Feiyu Yu , Xiangliang Kong , Fan Guo , Wenlong Liu , Zelong Jiang , Yao Chen , Joe Giacalone

We measure the far-infrared emission of the general quasar (QSO) population using Planck observations of the Baryon Oscillation Spectroscopic Survey QSO sample. By applying multi-component matched multi-filters to the seven highest Planck…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-21 Loïc Verdier , Jean-Baptiste Melin , James G. Bartlett , Christophe Magneville , Nathalie Palanque-Delabrouille , Christophe Yèche

The flat spectrum radio quasars (FSRQs) are a sub-class of blazars characterised by prominent optical emission lines and a collimated large-scale jet along the observer line of sight. An X-ray spectral flattening has been reported in FSRQs…

High Energy Astrophysical Phenomena · Physics 2021-06-16 Haritma Gaur , Prashanth Mohan , Ashwani Pandey

We present a new scenario of the emissive origin in the Steep Power Law (SPL) state of X-ray Binaries. The power-law component of X-ray emission is the synchrotron radiation of relativistic electrons in highly magnetized compact spots…

High Energy Astrophysical Phenomena · Physics 2009-05-19 Jiancheng Wang , Lihong Yan

One of the main, unresolved questions about the nature of quasars is the position of the acceleration site responsible for the highest energies. The attempt to investigate this question in the energy regime with the highest resolution, the…

High Energy Astrophysical Phenomena · Physics 2014-01-08 Stephan Richter , Felix Spanier

Four persistent (Cygnus X-1, GX 339-4, GRS 1758-258 and 1E 1740.7-2942) and three transient (GS 2023+38, GRO J0422+32 and GS 1354-64) black hole X-ray binary systems have been extensively observed at radio wavelengths during extended…

Astrophysics · Physics 2009-10-31 R. P. Fender

We present optical spectroscopic data for a complete sample of 161 S_5GHz >= 0.2 Jy, flat-spectrum radio sources. The sources were observed as part of a survey for high redshift, radio-loud quasars, and were selected for spectroscopic…

Astrophysics · Physics 2015-06-24 I. M. Hook , R. G. McMahon , M. J. Irwin , C. Hazard

Blazars are promising candidates for high energy neutrino sources, yet the physical origin of their neutrino emission remains uncertain. In this work, we extend our previous study by modeling the broadband spectral energy distributions…

High Energy Astrophysical Phenomena · Physics 2026-05-12 Hubing Xiao , Zhihao Ouyang , Lili Yang , Jingtian Zhu , Minfeng Gu , Liang Chen , Shaohua Zhang , Zhijian Luo , Junhui Fan

We use statistical results from a large sample of about 500 blazars, based on two surveys, the Deep X-ray Radio Blazar Survey (DXRBS), nearly complete, and the RASS-Green Bank survey (RGB), to provide new constraints on the spectral energy…

Astrophysics · Physics 2009-11-07 P. Padovani , E. Perlman , H. Landt , P. Giommi , M. Perri

Many years of study have failed to conclusively establish relations between a quasar's spectral energy distribution (SED) and the emission lines it is thought to produce. This is at least partially due to the lack of well-observed SEDs. We…

Astrophysics · Physics 2007-05-23 B. J. Wilkes , P. J. Green , S. Mathur , J. C. McDowell

In inhomogeneous optically thick synchrotron sources a substantial part of the electron population at low energies can be hidden by self-absorption and overpowered by high energy electrons in optically thin emission. These invisible…

Astrophysics · Physics 2009-11-07 Thomas Beckert , Heino Falcke

We present the results of our study of spectral energy distributions (SEDs) of a sample of ten low- to intermediate-synchrotron-peaked blazars. We investigate some of the physical parameters most likely responsible for the observed…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Bindu Rani , Alok C. Gupta , R. Bachev , A. Strigachev , E. Semkov , F. D'Ammando , P. J. Wiita , M. A. Gurwell , E. Ovcharov , B. Mihov , S. Boeva , S. Peneva

From a Principal Component Analysis (PCA) of 78 z~3 high quality quasar spectra in the SDSS-DR7, we derive the principal components characterizing the QSO continuum over the full wavelength range available. The shape of the mean continuum,…

In the restframe UV, two of the parameters that best characterize the range of emission-line properties in quasar broad emission-line regions are the equivalent width and the blueshift of the CIV line relative to the quasar rest frame. We…

We present results based on the first 20 Chandra images obtained in a survey of jets in radio selected flat-spectrum quasars (FSRQs), along with new sub-arcsecond radio maps and optical images. We discover jet X-ray flux in 12 sources…

This paper presents XMM-Newton and Chandra X-ray spectroscopy of ten flat-spectrum radio quasars (FSRQ) which are candidates to have an X-ray spectrum dominated by jet synchrotron emission. In all these FSRQ, which are less strongly…

Astrophysics · Physics 2010-11-11 Hermine Landt , Paolo Padovani , Paolo Giommi , Matteo Perri , Chi C. Cheung

We present new mid-infrared and submillimetre observations for a sample of eight high redshift type-2 QSOs located in the Chandra Deep Field South. The sources are X-ray absorbed with luminosities in excess of 10^44 erg/s. Two of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 D. Rigopoulou , V. Mainieri , O. Almaini , A. Alonso-Herrero , J. -S. Huang , G. Hasinger , G. Rieke , J. Dunlop , I. Lehmann

We present a multiwavelength study of the black hole X-ray binary V404 Cyg in quiescence, focusing upon the spectral energy distribution (SED). Radio, optical, UV, and X-ray coverage is simultaneous. We supplement the SED with additional…

High Energy Astrophysical Phenomena · Physics 2015-05-13 R. I. Hynes , C. K. Bradley , M. Rupen , E. Gallo , R. P. Fender , J. Casares , C. Zurita

The Flat Spectrum Radio Quasar PMN J2345-1555 is a bright gamma-ray source, that recently underwent a flaring episode in the IR, UV and gamma-ray bands. The flux changed quasi simultaneously at different frequencies, suggesting that it was…

High Energy Astrophysical Phenomena · Physics 2015-06-15 G. Ghisellini , F. Tavecchio , L. Foschini , G. Bonnoli , G. Tagliaferri