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Paolo Padovani Eric Perlman Hermine Landt Paolo Giommi Matteo Perri 《Astrophysics and Space Science》2004,294(1-2):71-78
We present a new population of radio quasars whose X-ray band, unlike previously known sources which have (flat) inverse Compton
radiation, is characterized by (steep) synchrotron emission, with a broad-band spectral energy distribution similar to that
of BL Lacs with high energy synchrotron peaks. We discuss how this new class was discovered, the class properties, and the
implications of its existence for our understanding of jets and active galactic nuclei in general. 相似文献
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D. A. Schwartz D. E. Harris H. Landt A. Siemiginowska H. L. Marshall J. M. Gelbord E. S. Perlman M. Georganopoulos M. Birkinshaw D. M. Worrall C. C. Cheung L. Stawarz S. G. Jorstad A. P. Marscher Y. Uchiyama C. M. Urry 《Astrophysics and Space Science》2007,311(1-3):341-345
We present a Chandra image of the quasar, jet, and lobes of PKS 1354+195 (=4C 19.44). The radio jet is 18 arcsec long, and appears to be very
straight. The length gives many independent spatial resolution elements in the Chandra image while the straightness implies that the geometrical factors are constant along the jet although their values are uncertain.
We also have 4 frequency radio images with half to one arcsecond angular resolution, and use HST and Spitzer data to study
the broad band spectral energy distributions. The X-ray and radio spectra are both consistent with a spectrum f
ν
∝
ν
−0.7 for the integrated jet. Using that spectral index, the model of inverse Compton scattering of electrons on the cosmic microwave
background (IC/CMB) gives magnetic field strengths and Doppler factors that are relatively constant along the jet. Extended
X-ray emission is evident in the direction of the otherwise unseen counter-jet. X-ray emission continues past the radio jet
to the South, and is detected within both the southern and northern radio lobes. 相似文献
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Hermine Landt Paolo Padovani †‡ Eric S. Perlman § Paolo Giommi Hayley Bignall Anastasios Tzioumis 《Monthly notices of the Royal Astronomical Society》2001,323(3):757-784
We have searched the archived, pointed ROSAT Position Sensitive Proportional Counter data for blazars by correlating the WGACAT X-ray data base with several publicly available radio catalogues, restricting our candidate list to serendipitous X-ray sources with a flat radio spectrum ( α r ≤0.70, where S ν ∝ ν − α ). This makes up the Deep X-ray Radio Blazar Survey (DXRBS). Here we present new identifications and spectra for 106 sources, including 86 radio-loud quasars, 11 BL Lacertae objects, and nine narrow-line radio galaxies. Together with our previously published objects and already-known sources, our sample now contains 298 identified objects: 234 radio-loud quasars [181 flat-spectrum quasars: FSRQ ( α r ≤0.50) and 53 steep-spectrum quasars: SSRQ], 36 BL Lacs and 28 narrow-line radio galaxies. Redshift information is available for 96 per cent of these. Thus our selection technique is ∼90 per cent efficient at finding radio-loud quasars and BL Lacs. Reaching 5-GHz radio fluxes ∼50 mJy and 0.1–2.0 keV X-ray fluxes a few ×10−14 erg cm−2 s−1 , DXRBS is the faintest and largest flat-spectrum radio sample with nearly complete (∼85 per cent) identification. We review the properties of the DXRBS blazar sample, including redshift distribution and coverage of the X-ray-radio–power plane for quasars and BL Lacs. Additionally, we touch upon the expanded multiwavelength view of blazars provided by DXRBS. By sampling for the first time the faint end of the radio and X-ray luminosity functions, this sample will allow us to investigate the blazar phenomenon and the validity of unified schemes down to relatively low powers. 相似文献
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