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We present a determination of the distributions of gamma-ray photon flux -- the so called LogN-LogS relation -- and photon spectral index for blazars, based on the third extragalactic source catalog of the Fermi Gamma-ray Space Telescope's…

High Energy Astrophysical Phenomena · Physics 2015-10-07 J. Singal

We present a determination of the distributions of photon spectral index and gamma-ray flux - the so called LogN-LogS relation - for the 352 blazars detected with a greater than approximately seven sigma detection threshold and located…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 J. Singal , V. Petrosian , M. Ajello

This is the first of a series of papers aimed at characterizing the populations detected in the high-latitude sky of the {\it Fermi}-LAT survey. In this work we focus on the intrinsic spectral and flux properties of the source sample. We…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-02 LAT Collaboration

The global contribution of unresolved gamma-ray point sources to the extragalactic gamma-ray background has been recently measured down to gamma-ray fluxes lower than those reached with standard source detection techniques, and by employing…

High Energy Astrophysical Phenomena · Physics 2020-05-27 Silvia Manconi , Michael Korsmeier , Fiorenza Donato , Nicolao Fornengo , Marco Regis , Hannes Zechlin

With ten years of operation and an exceptional dataset, the Fermi-Large Area Telescope allows us to unveil the detailed composition of the extragalactic $\gamma$-ray sky above $\rm 100\,MeV$. In this paper, we derive the intrinsic…

High Energy Astrophysical Phenomena · Physics 2020-06-09 Lea Marcotulli , Mattia Di Mauro , Marco Ajello

The Fermi Large Area Telescope (LAT) Collaboration has recently released the Third Catalog of Hard Fermi-LAT Sources (3FHL), which contains 1556 sources detected above 10 GeV with seven years of Pass 8 data. We investigate the source count…

High Energy Astrophysical Phenomena · Physics 2021-12-07 Mattia Di Mauro , Silvia Manconi , Hannes-S. Zechlin , Marco Ajello , Eric Charles , Fiorenza Donato

We compute the contribution of blazars (Flat Spectrum Radio Quasars and BL-Lacs) to the Fermi-LAT Extragalactic gamma-ray Background, assuming a gamma-ray luminosity function proportional to the luminosity function of radio galaxies and the…

High Energy Astrophysical Phenomena · Physics 2011-11-01 Massimo Cavadini , Ruben Salvaterra , Francesco Haardt

We examine the constraints on the luminosity-dependent density evolution model for the evolution of blazars given the observed spectrum of the diffuse gamma-ray background (DGRB), blazar source-count distribution, and the blazar spectral…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Kevork N. Abazajian , Steve Blanchet , J. Patrick Harding

We present an analysis of the intrinsic (unattenuated by the extragalactic background light, EBL) power-law spectral indices of 128 extragalactic sources detected up to z~2 with the Fermi-Large Area Telescope (LAT) at very high energies…

High Energy Astrophysical Phenomena · Physics 2015-11-11 Alberto Domínguez , Marco Ajello

Blazars constitute the most enigmatic class of extragalactic gamma-ray sources, and their observational features have been ascribed to a relativistic jet closely aligned to the line of sight. They are generally divided in two main classes:…

High Energy Astrophysical Phenomena · Physics 2015-06-04 R. D'Abrusco , F. Massaro. M. Ajello , J. E. Grindlay , H. A. Smith , G. Tosti

We present the results of the $\gamma$-ray flux distribution study on the brightest blazars which are observed by the \emph{Fermi}-LAT. We selected 50 brightest blazars based on the maximum number of detection reported in the LAT third AGN…

High Energy Astrophysical Phenomena · Physics 2018-11-07 Zahir Shah , N. Mankuzhiyil , A. Sinha , R. Misra , S. Sahayanathan , N. Iqbal

The source-count distribution as a function of their flux, dN/dS, is one of the main quantities characterizing gamma-ray source populations. We employ statistical properties of the Fermi Large Area Telescope (LAT) photon counts map to…

High Energy Astrophysical Phenomena · Physics 2016-07-28 Hannes-S. Zechlin , Alessandro Cuoco , Fiorenza Donato , Nicolao Fornengo , Andrea Vittino

Fermi-LAT LCR provide continuous and regularly-sampled gamma-ray light curves, spanning about 14 years, for a large sample of blazars. The log-normal flux distribution and linear RMS-Flux relation of the light curves for a few of Fermi…

High Energy Astrophysical Phenomena · Physics 2023-07-21 Na Wang , Ting-Feng Yi , Liang Wang , Li-Sheng Mao , Zhi-Yuan Pu , Gong-Ming Ning , Wei-Tian Huang , He Lu , Shun Zhang , Yu-Tong Chen , Liang Dong

Blazars represent the most abundant class of high-energy extragalactic $\gamma$-ray sources. The subset of blazars known as BL Lac objects is on average closer to Earth and characterized by harder spectra at high energy than the whole…

High Energy Astrophysical Phenomena · Physics 2016-05-26 M. Di Mauro , F. Donato , G. Lamanna , D. A. Sanchez , P. D. Serpico

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis,…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-20 LAT Collaboration

Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of 6 years of Fermi-LAT data to…

High Energy Astrophysical Phenomena · Physics 2016-08-01 Hannes-S. Zechlin , Alessandro Cuoco , Fiorenza Donato , Nicolao Fornengo , Marco Regis

We present the redshift evolutions and distributions of the gamma-ray luminosity and photon spectral index of flat spectrum radio quasar (FSRQ) type blazars, using non-parametric methods to obtain the evolutions and distributions directly…

High Energy Astrophysical Phenomena · Physics 2015-06-19 J. Singal , A. Ko , V. Petrosian

The spectral shapes of the contributions of different classes of unresolved gamma-ray emitters can provide insight into their relative contributions to the extragalactic gamma-ray background (EGB) and the natures of their spectra at GeV…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Tonia M. Venters , Vasiliki Pavlidou

Among the ~2157 unassociated sources in the third data release (DR3) of the fourth Fermi catalog, ~1200 were observed with the Neil Gehrels Swift Observatory pointed instruments. These observations yielded 238 high S/N X-ray sources within…

High Energy Astrophysical Phenomena · Physics 2023-02-15 Amanpreet Kaur , Stephen Kerby , Abraham D. Falcone

We present new theoretical estimates of the relative contributions of unresolved blazars and star-forming galaxies to the extragalactic gamma-ray background (EGB) and discuss constraints on the contributions from alternative mechanisms such…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Floyd W. Stecker , Tonia M. Venters
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