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We have observed 3C~279 in a gamma-ray flaring state in November 2008. We construct quasi-simultaneous spectral energy distributions (SEDs) of the source for the flaring period of 2008 and during a quiescent period in May 2010. Data have…

Relativistic jets from accreting supermassive black holes at cosmological distances can be powerful emitters of $\gamma$-rays. However, the precise mechanisms and locations responsible for the dissipation of energy within these jets,…

高能天体物理现象 · 物理学 2025-01-03 Sushmita Agarwal , Amit Shukla , Karl Mannheim , Bhargav Vaidya , Biswajit Banerjee

High redshift blazars are among the most powerful non-explosive sources in the Universe and play a crucial role in understanding the evolution of relativistic jets. To understand these bright objects, we performed a detailed investigation…

高能天体物理现象 · 物理学 2024-01-29 N. Sahakyan , G. Harutyunyan , S. Gasparyan , D. Israyelyan

Flaring activity from the jets of active galactic nuclei has been studied for several decades, closely related to the loading and evolution of the jet. In this work, we focus on the sub-hundred parsec jet region, well traced by non-thermal…

高能天体物理现象 · 物理学 2026-04-07 Alina Kochocki , Emma Kun , Sam Hori

3C 454.3 is frequently observed in flaring state. The long term light curve of this source has been analysed with 9 year (August 2008 - July 2017) data from Fermi LAT detector. We have identified five flares and one quiescent state. The…

高能天体物理现象 · 物理学 2020-05-06 Avik Kumar Das , Raj Prince , Nayantara Gupta

We present multiwavelength spectral analyses of two Fermi-LAT blazars, OJ 287 and 3C 279, that are part of the Boston University multiwaveband polarization program. The data have been compiled from observations with Fermi, RXTE, the VLBA,…

In July 2007, the blazar 3C 454.3 underwent a flare in the optical, reaching R~13 on July 19. Then the optical flux decreased by one magnitude, being R~14 when the source was detected by the gamma-ray satellite AGILE, that observed the…

天体物理学 · 物理学 2009-11-13 G. Ghisellini , L. Foschini , F. Tavecchio , E. Pian

III Zw 2 is the prototype of radio-intermediate quasars. Although there is the evidence of possessing strong jet, significant $\gamma$-ray emission has not been reported before. In this work, we carry out a detailed analysis of the latest…

高能天体物理现象 · 物理学 2016-10-19 Neng-Hui Liao , Yu-Liang Xin , Xu-Liang Fan , Shan-Shan Weng , Shao-Kun Li , Liang Chen , Yi-Zhong Fan

High-energy blazar light curves, in X-rays and beyond, have historically preferred a log-normal flux distribution, signifying multiplicative processes either in the jet itself or due to connection(s) with accretion. Here we present 18 year…

高能天体物理现象 · 物理学 2026-01-27 Agniva Roychowdhury

The broadband spectrum of a BL Lac object, OJ 287, from radio to $\gamma$-rays obtained during a major $\gamma$-ray flare detected by \emph{Fermi} in 2009 are studied to understand the high energy emission mechanism during this episode.…

高能天体物理现象 · 物理学 2013-09-24 Pankaj Kushwaha , S. Sahayanathan , K. P. Singh

Transition blazars exhibit a shift from one subclass to the next during different flux states. It is therefore crucial to study them to understand the underlying physics of blazars. We probe the origin of the multi-wavelength emission from…

高能天体物理现象 · 物理学 2023-11-17 Ashwani Pandey , Pankaj Kushwaha , Paul J. Wiita , Raj Prince , Bozena Czerny , C. S. Stalin

Context. Important information on the evolution of the jet can be obtained by comparing the physical state of the plasma at its propagation through the broad-line region (where the jet is most likely formed) into the intergalactic medium,…

高能天体物理现象 · 物理学 2017-12-06 D. Zargaryan , S. Gasparyan , V. Baghmanyan , N. Sahakyan

We study the jet physics of the BL Lac object PKS 2233-148 making use of synergy of observational data sets in the radio and gamma-ray energy domains. The four-epoch multi-frequency (4-43 GHz) VLBA observations focused on the parsec-scale…

高能天体物理现象 · 物理学 2018-11-28 A. B. Pushkarev , M. S. Butuzova , Y. Y. Kovalev , T. Hovatta

For more than 15 years, since the days of the Energetic Gamma-Ray Experiment Telescope (EGRET) on board the Compton Gamma-Ray Observatory (CGRO; 1991-2000), it has remained an open question why the prominent blazar 3C 345 was not reliably…

We investigate the dissipation of the bulk kinetic energy of a relativistic jet at different distances from the central power--house and analyse in detail how the dissipated energy is radiated away. We assume that the location of the…

天体物理学 · 物理学 2008-11-26 K. Katarzynski , G. Ghisellini

The large scale jet of quasar 3C 273 has been observed in radio to $\gamma$ ray frequencies. Earlier the X-ray emission from knot A of this jet has been explained with inverse Compton scattering of the cosmic microwave background radiations…

高能天体物理现象 · 物理学 2014-08-01 Esha Kundu , Nayantara Gupta

In October 2024, the object BL Lacertae experienced the brightest flaring event in gamma-ray ($>$100 MeV) with a historically bright $\gamma$-ray flux of $\sim$2.59 $\times 10^{-5}$ erg cm$^{-2}$ s$^{-1}$ with a detection of a 175.7 GeV…

高能天体物理现象 · 物理学 2025-07-08 Joysankar Majumdar , Sakshi Maurya , Raj Prince

BL Lacertae, the prototype of the BL Lacertae (BL Lac) category of blazars, underwent a giant $\gamma-$ray flare in April 2021. The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (hereafter Fermi-LAT) observed a peak…

高能天体物理现象 · 物理学 2022-12-21 Ashwani Pandey , C. S. Stalin

We analyze the shock-in-jet models for the gamma-ray flaring blazars 0420-014, OJ 287, and 1156+295 presented in Aller et al. (2014, Paper I), quantifying how well the modeling constrains internal properties of the flow (low energy spectral…

高能天体物理现象 · 物理学 2015-06-23 Philip A. Hughes , Margo F. Aller , Hugh D. Aller

Fermi-LAT observations provide continuous and regularly-sampled measurements of gamma-ray photon flux for hundreds of blazars. Many of these light curves, spanning almost 15 years, have been thoroughly examined for periodicity in multiple…

高能天体物理现象 · 物理学 2023-09-26 Polina Novikova , Ekaterina Shishkina , Dmitry Blinov