A Synchrotron Self-Compton Scenario for the Very High Energy γ-ray Emission of the Intermediate BL Lacertae object W Comae

نویسنده

  • Jin Zhang
چکیده

W Comae has significant variability in multi-wavelengthes, from the radio to the gamma-ray bands. A bright outburst in the optical and X-ray bands was observed in 1998, and most recently, a strong TeV flare was detected by VERITAS in 2008. It is the first TeV intermediate-frequency-peaked BL Lacertae (IBL) source. I find that both the broadband spectral energy distributions (SEDs) quasi-simultaneously obtained during the TeV flare and during the optical/X-ray outburst are well fit by using a single-zone synchrotron + synchrotron-self-Compton (SSC) model. The satisfactory fitting requires a large beaming factor, i.e., δ ∼ 25 and δ ∼ 20 for the TeV flare and the optical/X-ray outburst, respectively, suggesting that both the optical/X-ray outburst and the TeV flare are from a relativistic jet. The size of the emission region of the TeV flare is three times larger than that of the optical/Xray outburst, and the strength of the magnetic field for the TeV flare is ∼ 14 times smaller than that of the X-ray/optical outburst, likely indicating that the region of the TeV flare is more distant from the core than that of the X-ray/optical outburst. The IC component of the TeV flare peaks at around 1.3 GeV, but it is around 20 MeV for the X-ray/optical outburst, lower than that for the TeV flare with 2 orders of magnitude. The model predicts that the optical/X-ray outburst might be accompanied by a strong MeV/GeV emission, but the TeV flare may be not associated with the X-ray/optical outburst. The GeV emission is critical to characterize the SEDs of the optical/X-ray outburst and the TeV flare. The predicted GeV flux is above the sensitivity of Fermi/LAT, and it could be verified with the observations by Fermi/LAT in near future.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

VERITAS Blazar Observations - Recent Results

We present the discovery of very high energy (VHE) gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 0806+524 (z=0.138) and the intermediate-frequency-peaked BL Lac object W Comae (z=0.102) with VERITAS. VHE emission was discovered from these objects during the 2007/2008 observing campaign, with a strong outburst from W Comae detected in mid-March, lasting a few days. Quasi-si...

متن کامل

Analysis of Five Fermi–LAT LBL/IBL BL Lac Objects: Examining the June 2011 γ–ray Flare of BL Lacertae

Constructing a unification scenario for active galactic nuclei (AGN) is a forefront field of study in contemporary astrophysics. These highly variable and energetic objects produce radiation in wavelengths from radio through γ–ray. As more detectors of the most energetic electromagnetic regimes are developing, so is our knowledge of the emission models responsible for this cosmic radiation. Bla...

متن کامل

First Results from a Search for Tev Emission from Bl Lacs out to Z=0.2

Two active galactic nuclei have been detected at TeV energies using the atmospheric Čerenkov imaging technique. The Whipple Observatory γ-ray telescope has been used to observe all the BL Lacertae objects in the northern hemisphere out to a redshift of 0.1. We report the tentative detection of VHE emission from a third BL Lac object, 1ES 2344+514. Progress in extending this survey out to z=0.2 ...

متن کامل

ar X iv : a st ro - p h / 98 06 24 9 v 1 1 8 Ju n 19 98 Analyzing the Multiwavelength Spectrum and Variability of BL Lacertae During the July 1997 Outburst

The multiwavelength spectrum of BL Lacertae during its July 1997 outburst is analyzed in terms of different models for the production of high-energy radiation from blazars. We find that a two-component γ-ray spectrum, consisting of a synchrotron self-Compton and an external Compton component, is required in order to yield an acceptable fit to the broadband spectrum. Our analysis indicates that ...

متن کامل

Predictions of the High - Energy Emission from BL Lac objects : The Case of

Spectral fitting of the radio through hard X-ray emission of BL Lac objects has previously been used to predict their level of high-energy (GeV – TeV) emission. In this paper, we point out that such spectral fitting can have very large uncertainties with respect to predictions of the VHE emission, in particular if no reliable, contemporaneous measurement of the GeV flux is available and the νF ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2009