The Astrophysical Journal (Jan 2023)
VERITAS Discovery of Very High Energy Gamma-Ray Emission from S3 1227+25 and Multiwavelength Observations
- 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
Affiliations
- A. Acharyya
- ORCiD
- Department of Physics and Astronomy, University of Alabama , Tuscaloosa, AL 35487, USA ; [email protected], [email protected]
- C. B. Adams
- ORCiD
- Physics Department, Columbia University , New York, NY 10027, USA
- A. Archer
- Department of Physics and Astronomy, DePauw University , Greencastle, IN 46135-0037, USA
- P. Bangale
- ORCiD
- Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware , Newark, DE 19716, USA
- W. Benbow
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- A. Brill
- ORCiD
- NASA/Goddard Space-Flight Center , Code 661, Greenbelt, MD 20771, USA
- J. L. Christiansen
- Physics Department, California Polytechnic State University , San Luis Obispo, CA 94307, USA
- A. J. Chromey
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- M. Errando
- ORCiD
- Department of Physics, Washington University , St. Louis, MO 63130, USA
- A. Falcone
- ORCiD
- Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University , University Park, PA 16802, USA
- Q. Feng
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- J. P. Finley
- Department of Physics and Astronomy, Purdue University , West Lafayette, IN 47907, USA
- G. M. Foote
- ORCiD
- Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware , Newark, DE 19716, USA
- L. Fortson
- ORCiD
- School of Physics and Astronomy, University of Minnesota , Minneapolis, MN 55455, USA
- A. Furniss
- ORCiD
- Department of Physics, California State University—East Bay , Hayward, CA 94542, USA
- G. Gallagher
- Department of Physics and Astronomy, Ball State University , Muncie, IN 47306, USA
- W. Hanlon
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- D. Hanna
- ORCiD
- Physics Department, McGill University , Montreal, QC H3A 2T8, Canada
- O. Hervet
- ORCiD
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California , Santa Cruz, CA 95064, USA
- C. E. Hinrichs
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA; Department of Physics and Astronomy, Dartmouth College , 6127 Wilder Laboratory, Hanover, NH 03755 USA
- J. Hoang
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California , Santa Cruz, CA 95064, USA
- J. Holder
- ORCiD
- Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware , Newark, DE 19716, USA
- W. Jin
- ORCiD
- Department of Physics and Astronomy, University of Alabama , Tuscaloosa, AL 35487, USA ; [email protected], [email protected]
- M. N. Johnson
- ORCiD
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California , Santa Cruz, CA 95064, USA
- P. Kaaret
- ORCiD
- Department of Physics and Astronomy, University of Iowa , Van Allen Hall, Iowa City, IA 52242, USA
- M. Kertzman
- Department of Physics and Astronomy, DePauw University , Greencastle, IN 46135-0037, USA
- D. Kieda
- ORCiD
- Department of Physics and Astronomy, University of Utah , Salt Lake City, UT 84112, USA
- T. K. Kleiner
- ORCiD
- DESY , Platanenallee 6, D-15738 Zeuthen, Germany
- N. Korzoun
- ORCiD
- Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware , Newark, DE 19716, USA
- F. Krennrich
- Department of Physics and Astronomy, Iowa State University , Ames, IA 50011, USA
- M. J. Lang
- ORCiD
- School of Natural Sciences, University of Galway , University Road, Galway, H91 TK33, Ireland
- M. Lundy
- ORCiD
- Physics Department, McGill University , Montreal, QC H3A 2T8, Canada
- G. Maier
- ORCiD
- DESY , Platanenallee 6, D-15738 Zeuthen, Germany
- C. E McGrath
- School of Physics, University College Dublin , Belfield, Dublin 4, Ireland
- M. J. Millard
- ORCiD
- Department of Physics and Astronomy, University of Iowa , Van Allen Hall, Iowa City, IA 52242, USA
- J. Millis
- Department of Physics and Astronomy, Ball State University , Muncie, IN 47306, USA; Department of Physics, Anderson University, 1100 East 5th Street, Anderson, IN 46012, USA
- C. L. Mooney
- ORCiD
- Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware , Newark, DE 19716, USA
- P. Moriarty
- ORCiD
- School of Natural Sciences, University of Galway , University Road, Galway, H91 TK33, Ireland
- R. Mukherjee
- ORCiD
- Department of Physics and Astronomy, Barnard College, Columbia University , New York, NY 10027, USA
- S. O’Brien
- ORCiD
- Physics Department, McGill University , Montreal, QC H3A 2T8, Canada
- R. A. Ong
- ORCiD
- Department of Physics and Astronomy, University of California , Los Angeles, CA 90095, USA
- M. Pohl
- ORCiD
- DESY , Platanenallee 6, D-15738 Zeuthen, Germany; Institute of Physics and Astronomy, University of Potsdam , 14476 Potsdam-Golm, Germany
- E. Pueschel
- ORCiD
- DESY , Platanenallee 6, D-15738 Zeuthen, Germany
- J. Quinn
- ORCiD
- School of Physics, University College Dublin , Belfield, Dublin 4, Ireland
- K. Ragan
- ORCiD
- Physics Department, McGill University , Montreal, QC H3A 2T8, Canada
- P. T. Reynolds
- Department of Physical Sciences, Munster Technological University , Bishopstown, Cork, T12 P928, Ireland
- D. Ribeiro
- ORCiD
- School of Physics and Astronomy, University of Minnesota , Minneapolis, MN 55455, USA
- E. Roache
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- I. Sadeh
- ORCiD
- DESY , Platanenallee 6, D-15738 Zeuthen, Germany
- A. C. Sadun
- ORCiD
- Department of Physics, University of Colorado Denver , Campus Box 157, P.O. Box 173364, Denver, CO 80217, USA
- L. Saha
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA
- M. Santander
- ORCiD
- Department of Physics and Astronomy, University of Alabama , Tuscaloosa, AL 35487, USA ; [email protected], [email protected]
- G. H. Sembroski
- Department of Physics and Astronomy, Purdue University , West Lafayette, IN 47907, USA
- R. Shang
- ORCiD
- Department of Physics and Astronomy, Barnard College, Columbia University , New York, NY 10027, USA
- M. Splettstoesser
- ORCiD
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California , Santa Cruz, CA 95064, USA
- A. K. Talluri
- School of Physics and Astronomy, University of Minnesota , Minneapolis, MN 55455, USA
- J. V. Tucci
- Department of Physics, Indiana University−Purdue University Indianapolis , Indianapolis, IN 46202, USA
- V. V. Vassiliev
- Department of Physics and Astronomy, University of California , Los Angeles, CA 90095, USA
- D. A. Williams
- ORCiD
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California , Santa Cruz, CA 95064, USA
- S. L. Wong
- ORCiD
- Physics Department, McGill University , Montreal, QC H3A 2T8, Canada
- The VERITAS Collaboration
- Talvikki Hovatta
- ORCiD
- Finnish Centre for Astronomy with ESO (FINCA), University of Turku , FI-20014, Turku, Finland; Aalto University Metsähovi Radio Observatory , Metsähovintie 114, 02540 Kylmälä, Finland
- Svetlana G. Jorstad
- ORCiD
- Institute for Astrophysical Research, Boston University , 725 Commonwealth Avenue, Boston, MA 02215, USA
- Sebastian Kiehlmann
- ORCiD
- Institute of Astrophysics , Foundation for Research and Technology-Hellas, GR-71110 Heraklion, Greece; Department of Physics, Univ. of Crete , GR-70013 Heraklion, Greece
- Anne Lähteenmäki
- ORCiD
- Aalto University Metsähovi Radio Observatory , Metsähovintie 114, 02540 Kylmälä, Finland; Aalto University Department of Electronics and Nanoengineering , P.O. BOX 15500, FI-00076 AALTO, Finland
- Ioannis Liodakis
- ORCiD
- Finnish Center for Astronomy with ESO, University of Turku , FI-20014, Finland
- Alan P. Marscher
- ORCiD
- Institute for Astrophysical Research, Boston University , 725 Commonwealth Avenue, Boston, MA 02215, USA
- Walter Max-Moerbeck
- ORCiD
- Departamento de Astronomía, Universidad de Chile , Camino El Observatorio 1515, Las Condes, Santiago, Chile
- Anthony C. S. Readhead
- ORCiD
- Owens Valley Radio Observatory, California Institute of Technology , Pasadena, CA 91125, USA
- Rodrigo Reeves
- ORCiD
- Departamento de Astronomá, Universidad de Conceptión , Concepción, Chile
- Paul S. Smith
- ORCiD
- Steward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA
- Merja Tornikoski
- ORCiD
- Aalto University Metsähovi Radio Observatory , Metsähovintie 114, 02540 Kylmälä, Finland
- DOI
- https://doi.org/10.3847/1538-4357/acd2d0
- Journal volume & issue
-
Vol. 950,
no. 2
p. 152
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.
Keywords
