학술논문
VERITAS Discovery of Very High Energy Gamma-Ray Emission from S3 1227+25 and Multiwavelength Observations
Document Type
article
Author
A. Acharyya; C. B. Adams; A. Archer; P. Bangale; W. Benbow; A. Brill; J. L. Christiansen; A. J. Chromey; M. Errando; A. Falcone; Q. Feng; J. P. Finley; G. M. Foote; L. Fortson; A. Furniss; G. Gallagher; W. Hanlon; D. Hanna; O. Hervet; C. E. Hinrichs; J. Hoang; J. Holder; W. Jin; M. N. Johnson; P. Kaaret; M. Kertzman; D. Kieda; T. K. Kleiner; N. Korzoun; F. Krennrich; M. J. Lang; M. Lundy; G. Maier; C. E McGrath; M. J. Millard; J. Millis; C. L. Mooney; P. Moriarty; R. Mukherjee; S. O’Brien; R. A. Ong; M. Pohl; E. Pueschel; J. Quinn; K. Ragan; P. T. Reynolds; D. Ribeiro; E. Roache; I. Sadeh; A. C. Sadun; L. Saha; M. Santander; G. H. Sembroski; R. Shang; M. Splettstoesser; A. K. Talluri; J. V. Tucci; V. V. Vassiliev; D. A. Williams; S. L. Wong; The VERITAS Collaboration; Talvikki Hovatta; Svetlana G. Jorstad; Sebastian Kiehlmann; Anne Lähteenmäki; Ioannis Liodakis; Alan P. Marscher; Walter Max-Moerbeck; Anthony C. S. Readhead; Rodrigo Reeves; Paul S. Smith; Merja Tornikoski
Source
The Astrophysical Journal, Vol 950, Iss 2, p 152 (2023)
Subject
Language
English
ISSN
1538-4357
Abstract
We report the detection of very high energy gamma-ray emission from the blazar S3 1227+25 (VER J1230+253) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). VERITAS observations of the source were triggered by the detection of a hard-spectrum GeV flare on 2015 May 15 with the Fermi-Large Area Telescope (LAT). A combined 5 hr VERITAS exposure on May 16 and 18 resulted in a strong 13 σ detection with a differential photon spectral index, Γ = 3.8 ± 0.4, and a flux level at 9% of the Crab Nebula above 120 GeV. This also triggered target-of-opportunity observations with Swift, optical photometry, polarimetry, and radio measurements, also presented in this work, in addition to the VERITAS and Fermi-LAT data. A temporal analysis of the gamma-ray flux during this period finds evidence of a shortest variability timescale of τ _obs = 6.2 ± 0.9 hr, indicating emission from compact regions within the jet, and the combined gamma-ray spectrum shows no strong evidence of a spectral cutoff. An investigation into correlations between the multiwavelength observations found evidence of optical and gamma-ray correlations, suggesting a single-zone model of emission. Finally, the multiwavelength spectral energy distribution is well described by a simple one-zone leptonic synchrotron self-Compton radiation model.