scholarly journals Correlations between γ-ray luminosity and magnetization of the jet as well as relativistic electron injection power: cases for Mrk 421, 3C 454.3 and 3C 279

2021 ◽  
Vol 503 (2) ◽  
pp. 2523-2538
Author(s):  
Wen Hu ◽  
Dahai Yan ◽  
Qianglin Hu
Keyword(s):  
Kinetic Equations ◽  
Electron Injection ◽  
Radiative Energy ◽  
Spectral Energy ◽  
Acceleration Process ◽  
Energy Distributions ◽  
New Finding ◽  
Injection Power ◽  
Dissipative Mechanism ◽  
Γ Ray

ABSTRACT By fitting high-quality and simultaneous multiwavelength spectral energy distributions at multiple epochs with a one-zone leptonic jet model, we study the jet properties of three famous blazars: Mrk 421, 3C 454.3 and 3C 279. In the jet model, the emitting electron energy distributions are calculated by solving the kinetic equations of electron injection, escape, adiabatic and radiative energy losses. To explore multidimensional parameter space systematically, we employ a Markov chain Monte Carlo fitting technique. The properties of the emission regions we have derived here are consistent with those in previous studies, for example, the particle-dominated and low-magnetization jet. The new finding is that there is a tight correlation between γ-ray luminosity and electron injection power and an anticorrelation between γ-ray luminosity and the jet magnetization parameter. The results suggest that the same energy-dissipative mechanism (such as a shock) could be operating in the jets of different types of blazars, and that the origin of γ-ray flares is associated with the particle acceleration process.

scholarly journals An empirical approach to the extragalactic background light from AEGIS galaxy SED-type fractions

2011 ◽  
Vol 7 (S284) ◽  
pp. 442-445
Author(s):  
Alberto Domínguez
Keyword(s):  
Galaxy Evolution ◽  
Direct Measurement ◽  
Spectral Energy ◽  
Intensity Level ◽  
Energy Distributions ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Luminosity Functions ◽  
Novel Method ◽  
Γ Ray

AbstractThe extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for γ-ray astronomy. However, the overall spectrum of the EBL between 0.1 and 1000 μm has never been determined directly, neither from observed luminosity functions (LFs), over a wide redshift range, nor from any multiwavelength observation of galaxy spectral energy distributions (SEDs). The evolving overall spectrum of the EBL is derived here utilizing a novel method based on observations only. It is emphasized that the local EBL seems already well constrained from the UV up to the mid-IR. Different independent methodologies such as direct measurement, galaxy counts, γ-ray attenuation and realistic EBL modelings point towards the same EBL intensity level. Therefore, a relevant contribution from Pop III stars to the local EBL seems unlikely.

scholarly journals Nonthermal Radiation of the Extreme TeV Blazar 1ES 0229+200 from Electromagnetic Cascades on Infrared Photon Field

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 494
Author(s):  
Timur Dzhatdoev ◽  
Vladimir Galkin ◽  
Egor Podlesnyi
Keyword(s):  
Galactic Nuclei ◽  
Spectral Energy ◽  
Emission Model ◽  
Energy Distributions ◽  
Extragalactic Background Light ◽  
Nonthermal Radiation ◽  
Photon Field ◽  
Emission Models ◽  
Infrared Photon ◽  
Γ Ray

Extreme TeV blazars (ETBs) are active galactic nuclei with jets presumably pointing towards the observer having their intrinsic (compensated for the effect of γ-ray absorption on extragalactic background light photons) spectral energy distributions (SEDs) peaked at an energy in excess of 1 TeV. These sources typically reveal relatively weak and slow variability as well as higher frequency of the low-energy SED peak compared to other classes of blazars. It proved to be exceedingly hard to incorporate all these peculiar properties of ETBs into the framework of conventional γ-ray emission models. ETB physics have recently attracted great attention in the astrophysical community, underlying the importance of the development of self-consistent ETB emission model(s). We propose a new scenario for the formation of X-ray and γ-ray spectra of ETBs assuming that electromagnetic cascades develop in the infrared photon field surrounding the central blazar engine. This scenario does not invoke compact fast-moving sources of radiation (so-called “blobs”), in agreement with the apparent absence of fast and strong variability of ETBs. For the case of the extreme TeV blazar 1ES 0229+200 we propose a specific emission model in the framework of the considered scenario. We demonstrate that this model allows to obtain a good fit to the measured SED of 1ES 0229+200.

A COMPREHENSIVE STATISTICAL DESCRIPTION OF RADIO-THROUGH- γ -RAY SPECTRAL ENERGY DISTRIBUTIONS OF ALL KNOWN BLAZARS

2016 ◽  
Vol 224 (2) ◽  
pp. 26 ◽  
Author(s):  
Peiyuan Mao ◽  
C. Megan Urry ◽  
Francesco Massaro ◽  
Alessandro Paggi ◽  
Joe Cauteruccio ◽  
...  
Keyword(s):  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Γ Ray

scholarly journals On the injection of relativistic electrons in the jet of 3C 279

2020 ◽  
Vol 493 (1) ◽  
pp. 410-426
Author(s):  
Wen Hu ◽  
Dahai Yan ◽  
Benzhong Dai ◽  
Wei Zeng ◽  
Qianglin Hu
Keyword(s):  
High Energy ◽  
Shock Acceleration ◽  
Spectral Energy ◽  
Emission Region ◽  
Relativistic Electrons ◽  
Emission Model ◽  
Energy Distributions ◽  
Gamma Prime ◽  
Injection Power ◽  
Best Fitting

ABSTRACT The acceleration of electrons in 3C 279 is investigated through analysing the injected electron energy distribution (EED) in a time-dependent synchrotron self-Compton+external Compton emission model. In this model, it is assumed that relativistic electrons are continuously injected into the emission region, and the injected EED [$Q_{\rm e}^\prime (\gamma ^\prime)$] follows a single power-law form with low- and high-energy cut-offs $\rm \gamma _{min}^{\prime }$ and $\rm \gamma _{max}^{\prime }$, respectively, and the spectral index n, i.e. $Q_{\rm e}^\prime (\gamma ^\prime)\propto \gamma ^{\prime -n}$. This model is applied to 14 quasi-simultaneous spectral energy distributions of 3C 279. The Markov Chain Monte Carlo (MCMC)-fitting technique is performed to obtain the best-fitting parameters and the uncertainties on the parameters. The results show that the injected EED is well constrained in each state. The value of n is in the range of 2.5–3.8, which is larger than that expected by the classic non-relativistic shock acceleration. However, the large value of n can be explained by the relativistic oblique shock acceleration. The flaring activity seems to be related to an increased acceleration efficiency, reflected in an increased $\gamma ^{\prime }_{\rm min}$ and electron injection power.

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 A Bayesian approach to modelling multimessenger emission from blazars using lepto-hadronic kinetic equations

2020 ◽  
Vol 500 (3) ◽  
pp. 3613-3630 ◽  
Author(s):  
Bruno Jiménez-Fernández ◽  
Hendrik Jan van Eerten
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Kinetic Equations ◽  
Neutrino Flux ◽  
Spectral Energy ◽  
Acceleration Process ◽  
Emission Model ◽  
Statistical Tool ◽  
Cross Correlations

ABSTRACT Blazar TXS 0506+056 is the main candidate for a coincident neutrino and gamma-ray flare event. In this paper, we present a detailed kinetic lepto-hadronic emission model capable of producing a photon and neutrino spectrum given a set of parameters. Our model includes a range of large-scale geometries and both dynamical and steady-state injection models for electrons and protons. We link this model with a Markov chain Monte Carlo sampler to obtain a powerful statistical tool that allows us to both fit the Spectral Energy Distribution and study the probability density functions and correlations of the parameters. Assuming a fiducial neutrino flux, we demonstrate how multimessenger observations can be modelled jointly in a Bayesian framework. We find the best parameters for each of the variants of the model tested and report on their cross-correlations. Additionally, we confirm that reproducing the neutrino flux of TXS 0506+056 requires an extreme proton to electron ratio either in the local acceleration process or from external injection.

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 Characterization of M dwarfs using optical mid-resolution spectra for exploration of small exoplanets

2020 ◽  
Author(s):  
Yohei Koizumi ◽  
Masayuki Kuzuhara ◽  
Masashi Omiya ◽  
Teruyuki Hirano ◽  
John Wisniewski ◽  
...  
Keyword(s):  
Sample Selection ◽  
Optical Spectra ◽  
Average Error ◽  
Spectral Energy ◽  
M Dwarfs ◽  
Energy Distributions ◽  
Fitting Procedures ◽  
Optical Region ◽  
Selection For

Abstract We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (Teff), and radii. Our spectra were obtained using several optical spectrometers with spectral resolutions that range from 1200 to 10000. As many as 97% of the observed M-type dwarfs have a spectral type of M3–M6, with a typical error of 0.4 subtype, among which the spectral types M4–M5 are the most common. We infer the Teff of our sample by fitting our spectra with theoretical spectra from the PHOENIX model. Our inferred Teff is calibrated with the optical spectra of M dwarfs whose Teff have been well determined with the calibrations that are supported by previous interferometric observations. Our fitting procedures utilize the VO absorption band (7320–7570 Å) and the optical region (5000–8000 Å), yielding typical errors of 128 K (VO band) and 85 K (optical region). We also determine the radii of our sample from their spectral energy distributions. We find most of our sample stars have radii of <0.6 R⊙, with the average error being 3%. Our catalog enables efficient sample selection for exoplanet surveys around nearby M-type dwarfs.

scholarly journals Liquid-Mirror Telescope Surveys

1998 ◽  
Vol 11 (1) ◽  
pp. 464-467
Author(s):  
P. Hickson
Keyword(s):  
Integration Time ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Ccd Cameras ◽  
Photometric Redshifts ◽  
Rotating Liquid ◽  
Liquid Mirrors ◽  
Under Construction ◽  
Optical Telescopes ◽  
Mirror Telescope

Abstract Recent advances in the technology of rotating liquid-mirrors now make feasible the construction of large optical telescopes for dedicated survey programs. Two three-metre-class astronomical telescopes have been built and asix-metre telescope is under construction. These instruments observe in zenith-pointing mode, using drift-scanning CCD cameras to record continuous imaging of a strip of sky typically 20 arcmin wide. This enables them to observe of order 100 square degrees of sky with an integration time of a few minutes per night. Data can be co-added from night to night in order to increase the depth of the survey. Liquid-mirror telescopes are particularly wellsuited to surveys using broad or intermediate bandwidth filters to obtain photometric redshifts and spectral energy distributions for faint galaxies and quasars.

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