A5060439232- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- High-Energy Particle Collisions Research
- Black Holes and Theoretical Physics
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Computational Physics and Python Applications
- Astrophysical Phenomena and Observations
- Atomic and Subatomic Physics Research
- Gyrotron and Vacuum Electronics Research
- Particle Detector Development and Performance
- Relativity and Gravitational Theory
- Radio Wave Propagation Studies
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Coding theory and cryptography
- Electromagnetic Compatibility and Measurements
Nanjing University
2024-2025
Hunan University of Arts and Science
2015-2024
Guangzhou University
2011-2024
China University of Petroleum, East China
2024
Urumqi General Hospital of PLA
2015
Guangzhou Institute of Geography
2015
National Chung Cheng University
2008
(Abridged) In this paper, multi-wavelength data are compiled for a sample of 1425 Fermi blazars to calculate their spectral energy distributions (SEDs). A parabolic function, $\log(\nu F_{\nu}) = P_1(\log\nu - P_2)^2 + P_3,$ is used SED fitting. Synchrotron peak frequency ($\log \nu_p$), curvature ($P_1$), flux ($\nu_{\rm p}F_{\rm \nu_p}$), and integrated ($\nu F_{\nu}$) successfully obtained 1392 (461 flat spectrum radio quasars-FSRQs, 620 BL Lacs-BLs 311 uncertain type-BCUs, 999 sources...
Abstract In this work, we present 8523 pairs of R -band optical photometry observations for the quasar 3C 454.3 made during period 2006 October–2018 February on 70 cm meniscus telescope at Abastumani Observatory, Georgia, to study its intraday variabilities (IDVs) and long-term variations, have come following results. (1) We detected 10 outbursts, a Δ = 3.825 mag variation, some IDVs. The IDV timescales are from 4.1 285 minutes, with corresponding variability amplitude being A 2.9%–43.67%....
Abstract In this paper, the multiwavelength data from radio to X-ray bands for 2709 blazars in 4FGL-DR3 catalog are compiled calculate their spectral energy distributions using a parabolic equation <?CDATA $\mathrm{log}(\nu {f}_{\nu })={P}_{1}{\left(\mathrm{log}\nu -{P}_{2}\right)}^{2}+{P}_{3}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>ν</mml:mi> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi>...
We selected 457 blazars (193 flat spectrum radio quasars, 61 low-synchrotron peaked blazars, 69 intermediate-synchrotron and 134 high-synchrotron blazars) from the second Fermi-LAT catalog (2FGL) of γ-ray sources, which have X-ray observations. calculated lower limits for their Doppler factors, δγ, compared with available factors apparent superluminal velocities in literature.
In this paper, we used the database of university Michigan Radio Astronomy Observatory (UMRAO) at three (4.8 GHz, 8.0 GHZ, and 14.5 GHz) radio frequency to analyze light curves by power spectral analysis method in search possible periodicity. The results showed that sources display astrophysically meaningful periodicity ranging from 2.2 20.8 years their frequencies. We also calculated variability parameters investigated correlations between parameter flux density. For parameters, found...
Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and beaming effect in region. We compiled X-ray observations for 138 (54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, 48 high-peaked objects) calculated their Doppler factors, δγ. It is interesting δγ, correlated luminosity.
Blazars are an extreme subclass of active galactic nuclei. Their rapid variability, luminous brightness, superluminal motion, and high variable polarization probably due to a beaming effect. However, this factor (or Doppler factor) is very difficult measure. Currently, good way estimate it use the time scale their radio flares. In $Letter$, we multiwavelength data factors reported in literatures for sample 86 flaring blazars detected by Fermi compute intrinsic spectral energy distributions,...
Abstract Studies and constraints on the emission region are crucial to blazar radiation mechanism. Yet previous works have mainly focused individual sources. In this work, we make use of largest latest spectral energy distribution fitting results in literature statistically study properties framework a one-zone leptonic model. Our reveal: (1) that flat-spectrum radio quasars (FSRQs) show lower electron ( γ p ≲ 1.6 × 10 3 ) than BL Lacertae objects (BL Lacs) tend stronger magnetic field B...
Abstract Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the AGNs is called blazars, which are believed to unified with Fanaroff-Riley type I/II (FRI/II) radio galaxies. Following our previous work (Fan et al.), we present a sample 2400 sources measured flux densities core extended components. The contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRII galaxies 104 unidentified sources. We...
Abstract Blazars show extreme observational properties that are due to the beaming effect with jet being close line of sight. It was found observed luminosity is anticorrelated synchrotron peak frequency but debeamed and positively correlated. In this work, we revisit correlation for a large sample 255 blazars from fourth Fermi catalog available Doppler factors. Our analysis comes following conclusions. (1) The radio, X-ray, γ -ray, all frequency, correlated frequency. anticorrelation...
Aiming to delineate the physical framework of blazars, we present an effective method estimate four important parameters based on idea proposed by \citet{BK95}, including upper limit central black hole mass $M$, Doppler factor $\delta$, distance along axis site $\gamma$-ray production $d$ (which then can be transformed into location $\gamma$-ray-emitting region $R_{\gamma}$) and propagation angle with respect accretion disk $\Phi$. To do so, adopt identical sample 809 {\it...
In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi γ-ray data is compiled to investigate the correlation both between spectral index luminosity, compare indexes αX, αγ, αXγ, αγXγ for different subclasses. We also investigated luminosity. The following results have been obtained. (1) Our analysis indicates that an anti-correlation exists whole sample. However, when we considered subclasses (FSRQs,...
Abstract Blazars are a subclass of active galactic nuclei with extreme observation properties, which is caused by the beaming effect, expressed Doppler factor ( $\delta$ ), in relativistic jet. an important parameter blazars paradigm to indicate all and many methods were proposed estimate its value. In this paper, we present method following Mattox et al. calculate lower limit on $\gamma$ -ray $\delta_{\gamma}$ ) for 809 selected Fermi /LAT-detected adopting available X-ray data. Our sample...
Active galactic nuclei (AGNs) have two major classes, namely radio loud AGNs and quiet AGNs. A small subset of the radio-loud is called blazars, which display extreme observational properties, such as rapid variability, high luminosity, variable polarization, superluminal motion. All those properties are probably due to a relativistic beaming effect with jet pointing close line sight. Observations suggest that orientation can be expressed by core-dominance parameter, R. The R, some extent,...
Abstract Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the AGNs is called blazars, which are believed to unified with Fanaroff-Riley type I II (FRI&II) radio galaxies. Following our previous work, we present a latest sample 966 sources measured flux densities core extended components. The includes 83 BL Lacs, 473 flat spectrum quasars, 101 Seyferts, 245 galaxies, 52 FRIs&IIs 12 unidentified sources. We...
Abstract In this paper, we discuss the relationship between spectral index and core-dominance parameter for blazars (BL Lacertae objects flat spectrum radio quasars). To do so, calculated indexes 38 BL using preliminary data of University Michigan Radio Astronomy Observatory (UMRAO) with those quasars from our previous paper (2008, PASJ, 60, 707). For parameters, mainly them flux densities given by Kovalev et al. (2005, AJ, 130, 2473). We have compiled a list parameters some sources...
In the present work, using data base of University Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8 GHz, 8GHZ, and 14.5 GHz), we studied polarization properties for 47 BL Lacertae objects: 38 selected Lac objects, 7 X-ray two inter-middle objects (Mkn 421 Mkn 501), found that: (1) polarizations higher frequency is than those lower frequency, (2) variability (3) correlated with spectral index, (4) core-dominance parameter known parameters, suggesting that...
In this work, the support vector machine (SVM) method is adopted to separate BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs) in plots of photon index against flux, αph∼logF, those variability index, αph∼logVI logVI∼logF. Then, we used dividing lines distinguish Lacs from FSRQs blazar candidates uncertain types Fermi/LAT catalogue. Our main conclusions are: 1. We by αph=−0.123logF+1.170 αph∼logF plot, αph=−0.161logVI+2.594 plot logVI=0.792logF+9.203 logVI∼logF plot. 2....