Results 51 to 60 of about 34,519 (239)

Multiwavelength study of high-redshift blazars [PDF]

Monthly notices of the Royal Astronomical Society, 2020
High-redshift blazars are among the most powerful objects in the Universe. The spectral and temporal properties of 33 distant blazars (z > 2.5) detected in the high-energy γ-ray band are investigated by analysing the Fermi-LAT and Swift Ultraviolet and
N. Sahakyan, D. Israyelyan, G. Harutyunyan, M. Khachatryan, S. Gasparyan   +4 more
semanticscholar   +1 more source

BL Lac Contribution to the Extragalactic Gamma-Ray Background [PDF]

, 2007
Very high energy gamma-rays from blazars traversing cosmological distances through the metagalactic radiation field can convert into electron-positron pairs in photon-photon collisions. The converted gamma-rays initiate electromagnetic cascades driven by
Aharonian, Aharonian, Aharonian, Bade, Beckmann, Chiang, Coppi, Costamante, Costamante, Fossati, Ghisellini, Gioia, Giommi, Gorbunov, Hunter, K. Mannheim, Kneiske, Kneiske, Kronberg, Laurent-Mühleisen, Maciolek-Niedzwiecki, Mannheim, Mannheim, Protheroe, Protheroe, Rector, Reimer, Reimer, Reimer, Ryu, Sigl, Sreekumar, Stawarz, Stawarz, Stecker, T. M. Kneiske, Waxman, Wei   +37 more
core   +2 more sources

The Nature of γ-Ray Variability in Blazars [PDF]

Astrophysical Journal, 2019
We present an in-depth and systematic variability study of a sample of 20 powerful blazars, including 12 BL Lacs and 8 flat-spectrum radio quasars, applying various analysis tools such as flux distribution, symmetry analysis, and time-series analysis on ...
G. Bhatta, N. Dhital
semanticscholar   +1 more source

Gaussian Process Modeling Fermi-LAT γ-Ray Blazar Variability: A Sample of Blazars with γ-Ray Quasi-periodicities [PDF]

, 2020
Blazar variability may be driven by stochastic processes. On the other hand, quasi-periodic oscillation (QPO) behaviors were recently reported to be detected in the Fermi-LAT data of blazars.
Shenbang Yang, D. Yan, Peng-fei Zhang, B. Dai, Li Zhang   +4 more
semanticscholar   +1 more source

Blazars at Very High Energies: Emission Modelling

Galaxies, 2022
Blazars are very broadband cosmic sources with spectra spanning over twenty orders of magnitude in frequency, down to the 100 MHz regime in the radio range, up to VHE at several tens of TeV.
Hélène Sol, Andreas Zech
doaj   +1 more source

Unveiling the nature of the unidentified gamma-ray sources III: gamma-ray blazar-like counterparts at low radio frequencies [PDF]

, 2013
About one third of the gamma-ray sources listed in the second Fermi LAT catalog (2FGL) have no firmly established counterpart at lower energies so being classified as unidentified gamma-ray sources (UGSs). Here we propose a new approach to find candidate
D'Abrusco, R., Funk, S., Giroletti, M., Masetti, N., Massaro, F., Nori, M., Paggi, A., Tosti, G.   +7 more
core   +3 more sources

The 3HSP catalogue of extreme and high-synchrotron peaked blazars [PDF]

Astronomy & Astrophysics, 2019
Aims. High-synchrotron peaked blazars (HSPs or HBLs) play a central role in very high-energy (VHE) γ-ray astronomy, and likely in neutrino astronomy. Currently, the largest compilation of HSP blazars, the 2WHSP sample, includes 1691 sources, but it is ...
Yu-Ling Chang, B. Arsioli, P. Giommi, P. Padovani, C. Brandt   +4 more
semanticscholar   +1 more source

A Machine Learning Approach for Predicting Black Hole Mass in Blazars Using Broadband Emission Model Parameters

Universe, 2022
Blazars are observed to emit non-thermal radiation across the entire electromagnetic spectrum from the radio to the very-high-energy γ-ray region. The broadband radiation measured from a blazar is dominated by emission from a relativistic plasma jet ...
Krishna Kumar Singh, Anilkumar Tolamatti, Sandeep Godiyal, Atul Pathania, Kuldeep Kumar Yadav   +4 more
doaj   +1 more source

Extreme blazars as counterparts of IceCube astrophysical neutrinos [PDF]

, 2016
We explore the correlation of $\gamma$-ray emitting blazars with IceCube neutrinos by using three very recently completed, and independently built, catalogues and the latest neutrino lists.
P. Padovani, E. Resconi, P. Giommi, B. Arsioli, Y. L. Chang   +4 more
openalex   +3 more sources

Optical spectroscopy of blazars for the Cherenkov Telescope Array [PDF]

Astronomy & Astrophysics, 2020
Context. Blazars are the most numerous class of High Energy (HE; E about 50 MeV - few 100 GeV) and Very High Energy (VHE; E about 100 GeV - 10 TeV) gamma-ray emitters.
P. Goldoni, S. Pita, C. Boisson, W. Max-Moerbeck, E. Kasai, D. Williams, F. D’Ammando, V. Navarro-Aranguiz, M. Backes, U. D. Almeida, J. Becerra-González, G. Cotter, O. Hervet, J. Lenain, E. Lindfors, H. Sol, S. Wagner   +16 more
semanticscholar   +1 more source