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We studied all blazars of known redshift detected by the Fermi satellite during its first three months survey. For the majority of them, pointed Swift observations ensures a good multiwavelength coverage, enabling us to to reliably…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 G. Ghisellini , F. Tavecchio , L. Foschini , G. Ghirlanda , L. Maraschi , A. Celotti

A direct search of $\gamma$-ray emission centered on multi-frequency selected candidates is a valuable complementary approach to the standard search adopted in current $\gamma$-ray Fermi-LAT catalogs. Our candidates are part of the 2WHSP…

High Energy Astrophysical Phenomena · Physics 2017-02-15 Bruno Arsioli , Yu-Ling Chang

We cross-matched the 6-year Swift/Burst Alert Telescope (BAT) survey of active galactic nuclei (AGN) with the AT20G radio survey of the southern sky, which is one of the largest high-frequency radio surveys available. With these data we…

High Energy Astrophysical Phenomena · Physics 2013-04-05 D. Burlon , G. Ghirlanda , T. Murphy , R. Chhetri , E. Sadler , M. Ajello

The Swift Burst Alert Telescope (BAT) is discovering interesting new objects while monitoring the sky in the 14-195 keV band. Here we present the X-ray properties and spectral energy distributions for two unusual AGN sources. Both NVSS…

High Energy Astrophysical Phenomena · Physics 2015-06-04 J. Drew Hogg , Lisa M. Winter , Richard Mushotzky , Christopher Reynolds , Margaret Trippe

Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. We study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN…

Most of the electromagnetic output of blazars (BL Lac objects and Flat Spectrum Radio Quasars) comes out in the gamma-ray band, making the Large Area Telescope [0.1-100 GeV] onboard the Fermi satellite and the Cherenkov telescopes crucial…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 G. Ghisellini

In preparation for GLAST, we have compiled a sample of blazar candidates to increase the pool of well studied AGN from which GLAST counterparts will be drawn. Sources were selected with our Figure of Merit (FoM) ranking; thus, they have…

The recent launch of Fermi / GLAST - coinciding with the MAXI workshop - opens a new era for studies of jet-dominated active galaxies, known as blazars. While the emission processes operating in various spectral bands in blazars are…

Astrophysics · Physics 2008-10-13 Greg Madejski , Jun Kataoka , Marek Sikora

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope discovered a rapid (about 5 days duration), high-energy (E >100 MeV) gamma-ray outburst from a source identified with the blazar PKS 1502+106 (OR 103, S3 1502+10,…

High Energy Astrophysical Phenomena · Physics 2012-08-27 The Fermi LAT Collaboration , the Multifrequency Campaing Collaboration

High-redshift ($z >3$) $\gamma$-ray blazars are rare, but they are crucial for our understanding of jet evolution, $\gamma$-ray production and propagation, and the growth of supermassive black holes in the early universe. A new analysis of…

High Energy Astrophysical Phenomena · Physics 2024-06-07 Hai Lei , Ying-Kang Zhang , Xiong Jiang , Sebastian Kiehlmann , Anthony C. S. Readhead , Liang Chen , Neng-Hui Liao , Tao An

We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and gamma-ray bands. Our unique data set has allowed us to demonstrate that the…

Relativistic jets manifest some of the most intriguing activities in the nuclear regions of active galaxies. Identifying the most powerful relativistic jets permits us to probe the most luminous accretion systems and, in turn, the most…

High Energy Astrophysical Phenomena · Physics 2024-11-07 Vaidehi S. Paliya

We study the $\gamma$-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars. Most of the sources have already been detected in the…

High Energy Astrophysical Phenomena · Physics 2018-08-08 B. Arsioli , G. Polenta

We report on Swift observations of four z>2 radio-loud quasars (0212+735, 0537-286, 0836+710, and 2149-307), classified as blazars. The sources, well-known emitters at soft-medium X-rays, were detected at >5sigma with the BAT experiment in…

High-redshift blazars are the most powerful extragalactic astrophysical sources ever detected in the high-energy gamma-ray band. In this study, we present a temporal and spectral analysis of the high-redshift blazar B3 1343+451 based on 14…

High Energy Astrophysical Phenomena · Physics 2024-07-08 Fan Wu , Wen Hu , Benzhong Dai

The gamma-ray energy spectra of bright blazars of the LAT Bright AGN Sample (LBAS) are investigated using Fermi-LAT data. Spectral properties (hardness, curvature and variability) established using a data set accumulated over 6 months of…

High Energy Astrophysical Phenomena · Physics 2015-05-18 LAT Collaboration

The Burst Alert Telescope (BAT) onboard Swift detected bright emission from 15--195 keV from the source SWIFT~J0746.3+2548 (J0746 in the following), identified with the optically-faint (R ~ 19), z=2.979 quasar SDSS J074625.87+244901.2. Here…

Astrophysics · Physics 2009-11-11 Rita M. Sambruna

We use 3 years of data from the Swift/BAT survey to select a complete sample of X-ray blazars above 15 keV. This sample comprises 26 Flat-Spectrum Radio Quasars (FSRQs) and 12 BL Lac objects detected over a redshift range of 0.03<z<4.0. We…

Cosmology and Nongalactic Astrophysics · Physics 2010-02-04 M. Ajello , L. Costamante , R. M. Sambruna , N. Gehrels , J. Chiang , A. Rau , A. Escala , J. Greiner , J. Tueller , J. V. Wall , R. F. Mushotzky

We report on a detailed investigation of the gamma-ray emission from 18 broad line radio galaxies (BLRGs) based on two years of Fermi Large Area Telescope (LAT) data. We confirm the previously reported detections of 3C 120 and 3C 111 in the…

We present the preliminary results from two new surveys of blazars that have direct implications on the GLAST detection of extragalactic sources from two different perspectives: microwave selection and a combined deep X-ray/radio selection.…