Results 141 to 150 of about 1,444 (209)

Testing general relativity with cosmological large scale structure. [PDF]

Gen Relativ Gravit, 2022
Durrer R.
europepmc   +1 more source

A Search for Synchrotron X-Ray Emission in Radio Quasars

, 2008
This paper presents XMM-Newton and Chandra X-ray spectroscopy of 10 flat-spectrum radio quasars (FSRQ) that are candidates to have an X-ray spectrum dominated by jet synchrotron emission. In all these FSRQ, which are less strongly relativistically beamed
Padovani, P., Cheung, C. C., Giommi, P., Perri, M., Landt, H.   +4 more
core   +1 more source

AGN torus emission for a homogeneous sample of bright flat-spectrum radio quasars

, 2015
We have selected a complete sample of 80 flat-spectrum radio quasars (FSRQs) from the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year catalog within the Sloan Digital Sky Survey (SDSS) area, all with measured redshift, and have inspected their ...
G. Castignani, G. De Zotti
core   +1 more source

Radiative Relativistic Turbulence as an In Situ Pair-plasma Source in Blazar Jets

The Astrophysical Journal
As powerful gamma-ray engines, blazars—relativistic plasma jets launched toward Earth from active galactic nuclei—are manifestly high-energy particle accelerators.
John M. Mehlhaff, Muni Zhou, Vladimir Zhdankin   +2 more
doaj   +1 more source

Hunting for Candidates of Changing-look Blazars Using Mclust Clustering Analysis

The Astrophysical Journal
C​​hanging-look blazars (CLBs) are blazars whose optical spectral lines at different epochs show significant changes and present a clear transition between standard FSRQ and BL Lacertae (BL Lac).
Shi-Ju Kang, Shan-Shan Ren, Yong-Gang Zheng, Qingwen Wu   +3 more
doaj   +1 more source

Optical Spectropolarimetric Variability Properties in Blazars PKS 0637–75 and PKS 1510–089

The Astrophysical Journal
Spectropolarimetry is a powerful tool to investigate the central regions of active galactic nuclei (AGNs) as polarization signatures are key to probing magnetic field structure, evolution, and the physics of particle acceleration in jets.
Stephanie A. Podjed, Ryan C. Hickox, Jedidah C. Isler, Markus Böttcher, Hester M. Schutte   +4 more
doaj   +1 more source

The Physical Properties of Changing-look Blazars

The Astrophysical Journal
Changing-look active galactic nuclei (AGNs) are a special class of AGNs that change their spectral type from type 1 to type 2 or vice versa. In recent years, a number of changing-look blazars (CLBs) were also reported, which transition between flat ...
Shi-Ju Kang, Bing Lyu, Qingwen Wu, Yong-Gang Zheng, Junhui Fan   +4 more
doaj   +1 more source

High-redshift obscured quasars

, 2007
Using mid-infrared and radio criteria, we select a sample of candidate z~2 obscured quasars. Optical spectroscopy confirms about half of these as type-2 quasars, and modelling the population suggests 50-80% of the quasars are obscured.
Rawlings, Steve2007, Martinez-Sansigre, Alejo, Rawlings, S, Martinez-Sansigre, A   +3 more
core  

Discovery of a ∼208 day Quasiperiodic Oscillation in the X-Ray Emission of the TeV Blazar 1ES 1959+650

The Astrophysical Journal
We report the discovery of a significant quasiperiodic oscillation (QPO) in the X-ray emission of the TeV blazar 1ES 1959+650 through a detailed timing analysis of long-term Swift X-ray Telescope data.
Bing-Kai Zhang, Min Jin, Peng Zong
doaj   +1 more source

From Nobeyama Radio Observatory to the international project ALMA -Evolution of millimeter and submillimeter wave astronomy in Japan. [PDF]

Proc Jpn Acad Ser B Phys Biol Sci, 2022
Ishiguro M, Chiba K, Sakamoto S.
europepmc   +1 more source