Multiwavelength study of VHE emission from Markarian 501 using TACTIC observations during April-May, 2012
Abstract
We have observed Markarian 501 in Very High Energy (VHE) gamma-ray wavelength band for 70.6 h from 15 April to 30 May, 2012 using TACTIC telescope. Detailed analysis of ∼66.3 h of clean data revealed the presence of a TeV γ-ray signal (686± 77 γ-ray events) from the source direction with a statistical significance of 8.89σ above 850 GeV. Further, a total of 375 ± 47 γ-ray like events were detected in 25.2 h of observation from 22 - 27 May, 2012 with a statistical significance of 8.05σ indicating that the source has possibly switched over to a relatively high gamma-ray emission state. We have derived time-averaged differential energy spectrum of the state in the energy range 850 GeV - 17.24 TeV which fits well with a power law function of the form dF / dE =f0E-Γ with f0 =(2.27 ± 0.38) ×10-11 photons cm-2 s-1 TeV-1 and Γ = 2.57 ± 0.15 . In order to investigate the source state, we have also used almost simultaneous multiwavelength observations viz: high energy data collected by Fermi-LAT, X-ray data collected by Swift-XRT and MAXI, optical and UV data collected by Swift-UVOT, and radio data collected by OVRO, and reconstructed broad-band Spectral Energy Distribution (SED). The obtained SED supports leptonic model (homogeneous single zone) for VHE gamma-ray emission involving synchrotron and synchrotron self Compton (SSC) processes.
- Publication:
-
New Astronomy
- Pub Date:
- July 2017
- DOI:
- 10.1016/j.newast.2017.01.004
- arXiv:
- arXiv:1701.04935
- Bibcode:
- 2017NewA...54...42C
- Keywords:
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- Blazars: Markarian 501;
- TeV γ-rays;
- Multi-wavelength observations;
- Data analysis;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 10