THE OPTICAL-X-RAY–GAMMA-RAY SPECTRAL ENERGY DISTRIBUTIONS OF GEV GAMMA-RAY LOUD BLAZARS AND CONNECTION AMONG LBLs, HBLs AND FSRQs

2003 ◽  
Vol 12 (05) ◽  
pp. 781-789 ◽  
Author(s):  
G. Z. XIE ◽  
S. X. DING ◽  
H. DAI ◽  
E. W. LIANG ◽  
H. T. LIU
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Spectral Energy ◽  
Spectral Indices ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Γ Ray ◽  
High Energy Emission ◽  
Bl Lacs

In this paper, we introduce a new composite spectral indices αγxγ = αxγ - αγ, and prove [Formula: see text], that means αγxγ is intrinsic. We plot a αxox - αγxγ diagram for 25 Gev γ-ray blazars for which αx and αγ have been provided in the literature, where αxox = αox - αx which was introduced by Sambruna et al. (1996) and proved that it is intrinsic by our previous paper (Xie et al. 2001). Using this new composite color–color (αxox - αγxγ) diagram, we investigated the nature of the HBLs–LBLs relationship, and the BL Lacs–FSRQs relationship, in high-energy emission. The results show that the spectral energy distributions of three subclasses of Gev γ-ray loud blazars are different, but essentially continuous: HBLs and FSRQs occupy separated regions while LBLs bridge the gap between HBLs and FSRQs. The results are consistent with that derived from a low energy color–color(αxox - αoro) diagram by Sambruna et al. (1996) and Xie et al. (2001). However, on the αox - αxγ diagram, FSRQs, LBLs and HBLs occupy same region. Because both αγxγ and αxox are intrinsic, thus, the new connection among HBLs, LBLs and FSRQs obtained by us is intrinsic.

scholarly journals Tracing the high energy emission of γ-ray detected radio loud quasars

2014 ◽  
Vol 10 (S313) ◽  
pp. 225-230
Author(s):  
Giulia Migliori
Keyword(s):  
Spectral Energy Distribution ◽  
High Energy ◽  
Host Galaxy ◽  
Spectral Energy ◽  
X Ray ◽  
Relativistic Jet ◽  
Quasar Jets ◽  
Γ Ray ◽  
High Energy Emission ◽  
Jet Power

AbstractWe present a multiwavelength study of the core and relativistic jet of the radio loud (RL) quasar RGB J1512+020A (z=0.20). We report the discovery of a bright, 13” extended X-ray jet with a short Chandra observation. We discuss the origin of the jet X-ray emission and its properties in comparison with sample of X-ray quasar jets. The broadband core spectrum is contributed by the emission of the central quasar, by a blazar component, responsible for the γ-ray emission detected by Fermi, and by the host galaxy. We model the non-thermal blazar spectral energy distribution (SED) and constrain the total jet power. The jet power inferred from the blazar SED modeling is in agreement with the values obtained from the total radio power, pointing to a jet that efficiently carries its power up to kiloparsec scales. The quasar emission appears intrinsically weak in the optical-UV band. The disk luminosity estimated from the broad emission lines is lower than the jet power, in agreement with recent results from observations and theory.

scholarly journals Extinction curves of GRB environment with the X-shooter

2015 ◽  
Vol 11 (A29B) ◽  
pp. 253-254
Author(s):  
Andreja Gomboc ◽  
Jure Japelj ◽  
Stefano Covino
Keyword(s):  
Rest Frame ◽  
Near Infrared ◽  
Gamma Ray ◽  
Spectral Energy ◽  
X Rays ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Unique Probe ◽  
Photometric Measurements

AbstractGamma Ray Bursts (GRBs) can be used as a powerful tool to study galactic environments at different epochs of the Universe's evolution, thanks to their bright afterglow emission ranging from X-rays to optical and radio wavebands. Important aspect of the environment is dust, which plays a central role in the astrophysical processes of interstellar medium and in the formation of stars. GRBs can be a unique probe of dust at cosmological distances, where its origin and properties are still poorly known. By using a sample of GRB afterglow spectra observed with the VLT/X-shooter spectrograph we studied the rest-frame extinction in GRB lines-of-sight by modelling the broadband near-infrared to X-ray afterglow spectral energy distributions. We present our results on the rest-frame extinction of our sample, and illustrate that the spectroscopic data, thanks to a combination of excellent resolution and coverage of the blue part of the spectral energy distributions, are more successful than photometric measurements in constraining the extinction curves and therefore the dust properties in GRB hosts.

scholarly journals TeV-peaked candidate BL Lac objects

2019 ◽  
Vol 491 (2) ◽  
pp. 2771-2778 ◽  
Author(s):  
L Costamante
Keyword(s):  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Flux Ratio ◽  
High Energy ◽  
Spectral Energy ◽  
Bl Lac Objects ◽  
X Ray ◽  
Cherenkov Telescopes ◽  
Bl Lac ◽  
Bl Lacs

ABSTRACT BL Lac objects can be extreme in two ways: with their synchrotron emission, peaking beyond 1 keV in their spectral energy distribution, or with their gamma-ray emission, peaking at multi-TeV energies up to and beyond 10–20 TeV, like 1ES 0229+200. This second type of extreme BL Lacs – which we can name TeV-peaked BL Lacs – is not well explained by the usual synchrotron self-Compton scenarios for BL Lacs. These sources are also important as probes for the intergalactic diffuse infrared background and cosmic magnetic fields, as well as possible sites of production of ultra-high-energy cosmic rays and neutrinos. However, all these studies are hindered by their still very limited number. Here I propose a new, simple criterium to select the best candidates for TeV observations, specifically aimed at this peculiar type of BL Lac objects by combining X-ray, gamma-ray, and infrared data. It is based on the observation of a clustering towards a high X-ray to GeV gamma-ray flux ratio, and it does not rely on the radio flux or X-ray spectrum. This makes it suitable to find TeV-peaked sources also with very faint radio emission. Taking advantage of the Fermi all-sky gamma-ray survey applied to the ROMA-BZCAT and Sedentary Survey samples, I produce an initial list of 47 TeV-peaked candidates for observations with present and future air-Cherenkov telescopes.

scholarly journals Multiwavelength study of potential blazar candidates among Fermi-LAT unidentified gamma-ray sources

2019 ◽  
Vol 15 (S356) ◽  
pp. 326-328
Author(s):  
Jean Damascène Mbarubucyeye ◽  
Felicia Krauß ◽  
Pheneas Nkundabakura
Keyword(s):  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Peak Position ◽  
Spectral Energy ◽  
Synchrotron Emission ◽  
Parabolic Model ◽  
X Ray ◽  
Single Radio ◽  
High Energy Emission

AbstractStudying unidentified γ-ray sources is important as they may hide new discoveries. We conducted a multiwavelength analysis of 13 unidentified Fermi-LAT sources in the 3FGL catalogue that have no known counterparts (Unidentified Gamma-ray Sources, UnIDs). The sample was selected for sources that have a single radio and X-ray candidate counterpart in their uncertainty ellipses. The purpose of this study is to find a possible blazar signature and to model the Spectral Energy Distribution (SED) of the selected sources using an empirical log parabolic model. The results show that the synchrotron emission of all sources peaks in the infrared (IR) band and that the high-energy emission peaks in MeV to GeV bands. The SEDs of sources in our sample are all blazar like. In addition, the peak position of the sample reveals that 6 sources (46.2%) are Low Synchrotron Peaked (LSP) blazars, 4 (30.8%) of them are High Synchrotron Peaked (HSP) blazars, while 3 of them (23.0%) are Intermediate Synchrotron Peaked (ISP) blazars.

scholarly journals Comptonization as Blazar High Energy Emission

1996 ◽  
Vol 175 ◽  
pp. 421-422 ◽  
Author(s):  
Oliver Dreissigacker
Keyword(s):  
Particle Acceleration ◽  
Gamma Ray ◽  
High Energy ◽  
Energy Output ◽  
Relativistic Electrons ◽  
X Ray ◽  
Γ Ray ◽  
Exotic Particle ◽  
Jet Plasma ◽  
High Energy Emission

We explain the overall continuous Grazar (Gamma Ray Blazar) spectrum from the synchrotron turnover to the EGRET GeV detections by means of Comptonization in the parsec scale jet's substructures.While making use of the constraints on the synchrotron spectrum and other measurable quantities, no exotic particle acceleration is needed to achieve the high energy output.We show, that the “Lighthouse Model” of blobs of relativistic electrons, travelling with the jet plasma at relativistic speeds, produce both, correct timescales and shapes for the lightcurve, and correct ratios and slopes of the synchrotron, X-ray and γ-ray branches.

MODELING OF NON-HBL VHE γ-RAY BLAZARS

2009 ◽  
Vol 18 (10) ◽  
pp. 1517-1521
Author(s):  
MARKUS BÖTTCHER
Keyword(s):  
High Energy ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Bl Lac Objects ◽  
Spectrum Radio ◽  
Bl Lac ◽  
Γ Ray ◽  
High Energy Emission ◽  
Radio Quasar ◽  
Negligible Contribution

This is a summary of recent modeling results of three newly detected TeV blazars of the intermediate BL Lac object (IBL) and flat-spectrum radio quasar (FSRQ) sub-classes: W Comae, 3C 66A, and 3C 279. For model fits to the spectral energy distributions of W Comae and 3C 66A, a non-negligible contribution from a source of soft radiation external to the jets of these blazars is strongly preferred over pure synchrotron-self-Compton or synchrotron-proton-blazar models, respectively. This indicates that IBLs are truly intermediate between the "classical" TeV blazars (high-frequency-peaked BL Lac objects) and FSRQs. The VHE γ-ray detection of the FSRQ 3C 279 poses severe challenges for leptonic models, and seems to favor a hadronic origin of the high-energy emission. However, even a hadronic model suffers from problems with extreme energy requirements.

scholarly journals The Classifications and Some Correlations for Fermi Blazars

2016 ◽  
Author(s):  
Junhui Fan ◽  
Y Liu ◽  
J.H. Yang ◽  
C Lin ◽  
J.M. Hao
Keyword(s):  
Spectral Index ◽  
Gamma Ray ◽  
Empirical Relation ◽  
Peak Frequency ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Peak Luminosity ◽  
Integrated Luminosity

In a recent paper, we calculate spectral energy distributions (SEDs) for 1425 Fermi blazars, classifications of low synchrotron peak sources (LSPs) if log $\nu_{\rm p} (\rm Hz) \leq $ 14.0, intermediate synchrotron peak sources (ISPs) if $14.0 < \,\log\, \nu_{\rm p} (\rm Hz) \leq 15.3 $, and high synchrotron peak sources (HSPs) if $ \log\, \nu_{\rm p} (\rm Hz) > 15.3$ are made based on 999 logarithms of synchrotron peak frequencies with known redshift, and we obtain an empirical relation to estimate the synchrotron peak frequency, $\nu_{\rm p}^{\rm Eq.}$ from effective spectral indexes $\alpha_{ox}\, {\rm and}\, \alpha_{ro}$ as $\log \nu_{\rm p}^{\rm Eq.} = 16+4.238X $ if $X < 0$, and $\log \nu_{\rm p}^{\rm Eq.} = 16+4.005Y $ if $X > 0$, where $X = 1.0 - 1.262 \alpha_{ro} - 0.623 \alpha_{ox}$, and $Y = 1.0 + 0.034 \alpha_{ro} - 0.978 \alpha_{ox}$ \cite{Fan16}. In the present work, we investigate the correlation between the peak frequency and the radio to X-ray spectral index, that between peak luminosity (integrated luminosity) and $\gamma$-ray/optical luminosity, and that between peak luminosity and integrated luminosity. Some discussions are presented.

scholarly journals The Far‐Infrared Spectral Energy Distributions of X‐Ray–selected Active Galaxies

2003 ◽  
Vol 590 (1) ◽  
pp. 128-148 ◽  
Author(s):  
Joanna K. Kuraszkiewicz ◽  
Belinda J. Wilkes ◽  
Eric ◽  
J. Hooper ◽  
Kim K. McLeod ◽  
...  
Keyword(s):  
Far Infrared ◽  
Active Galaxies ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Infrared Spectral

scholarly journals Fermi-LAT and WMAP observations of the supernova remnant Puppis A

2013 ◽  
Vol 9 (S296) ◽  
pp. 295-299
Author(s):  
Marie-Hélène Grondin ◽  
John W. Hewitt ◽  
Marianne Lemoine-Goumard ◽  
Thierry Reposeur ◽  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
High Energy ◽  
Radio Spectrum ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Large Area ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

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