593 datasets found

Gamma-ray bursts (GRBs) are fascinating events due to their panchromatic nature. We study optical plateaus in GRB afterglows via an extended search into archival data. We...

The origin of {gamma}-ray flares observed from blazars is one of the major mysteries in jet physics. We have attempted to address this problem following a novel spectral energy...

We present a morphological and spectral study of a sample of 99 BL Lac objects using the LOFAR Two-Metre Sky Survey Second Data Release (LDR2). Extended emission has been...

We present initial results from a Hubble Space Telescope snapshot imaging survey of the host galaxies of Swift-BAT active galactic nuclei (AGN) at z<0.1. The hard X-ray...

We present the first Fermi Large Area Telescope (LAT) catalog of long-term {gamma}-ray transient sources (1FLT). This comprises sources that were detected on monthly time...

Fermi-LAT's detection of {gamma}-rays from narrow-line Seyfert 1 galaxies (NLS1s) has received increasing attention. Understanding these {gamma}-NLS1s is of interest because...

Gamma-ray bursts (GRBs) are highly variable and exhibit strong spectral evolution. In particular, the emission properties vary from pulse to pulse in multipulse bursts. Here we...

As a follow-up to the optical spectroscopic campaign aimed at achieving completeness in the Third Catalog of Hard Fermi-LAT Sources (3FHL), we present here the results of a...

We present a catalog of central engine properties, i.e., black hole mass (M_BH_) and accretion luminosity (L_disk_), for a sample of 1077 blazars detected with the Fermi Large...

3C 454.3 is frequently observed in the flaring state. The long-term light curve of this source has been analyzed with 9yr (2008 August - 2017 July) of data from the Fermi-LAT...

We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses,...

Associating {gamma}-ray sources to their low-energy counterparts is one of the major challenges of modern {gamma}-ray astronomy. In the context of the Fourth Fermi Large Area...

The exact relationship between the long gamma-ray burst (LGRB) rate and the cosmic star formation rate (CSFR) is essential for using LGRBs as cosmological probes. In this work,...

We present the fourth Fermi Large Area Telescope catalog (4FGL) of {gamma}-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope...

We present the results from the timing and spectral study of Mrk 421 based mainly on the Swift data in the X-ray energy range obtained during the time interval 2015...

Extreme high-frequency-peaked BL Lac objects (EHBLs) are blazars that exhibit extremely energetic synchrotron emission. They also feature nonthermal gamma-ray emission whose...

We present the detailed timing and spectral results obtained during the Swift observations of the TeV-detected blazar 1ES 1959+650 in 2016 August-2017 November. The source...

We present a search for spatial extension in high-latitude (|b|>5{deg}) sources in recent Fermi point source catalogs. The result is the Fermi High-Latitude Extended Sources...

Based on broadband spectral energy distributions (SEDs), we estimate the jet physical parameters of 1392 {gamma}-ray-loud active galactic nuclei (AGNs), the largest sample so...

Hard X-ray (>=10keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The...