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  • VERITAS Observations of the...
    Adams, C. B.; Benbow, W.; Brill, A.; Brose, R.; Buchovecky, M.; Capasso, M.; Christiansen, J. L.; Chromey, A. J.; Daniel, M. K.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fortson, L.; Furniss, A.; Gent, A.; Gillanders, G. H.; Giuri, C.; Hanna, D.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Jin, W.; Kaaret, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krennrich, F.; Kumar, S.; Lang, M. J.; Lundy, M.; Maier, G.; Moriarty, P.; Mukherjee, R.; Nieto, D.; Nievas-Rosillo, M.; O’Brien, S.; Ong, R. A.; Otte, A. N.; Pfrang, K.; Pohl, M.; Prado, R. R.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Ribeiro, D.; Richards, G. T.; Roache, E.; Ryan, J. L.; Santander, M.; Schlenstedt, S.; Sembroski, G. H.; Shang, R.; Stevenson, B.; Wakely, S. P.; Weinstein, A.; Williams, D. A.

    Astrophysical journal/˜The œAstrophysical journal, 06/2021, Letnik: 913, Številka: 2
    Journal Article

    Abstract The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of nonthermal radiation. The inner 375 pc × 600 pc region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants (SNRs). We present the results of our improved analysis of the very-high-energy gamma-ray emission above 2 TeV from the GC using 125 hr of data taken with the Very Energetic Radiation Imaging Telescope Array System imaging-atmospheric Cerenkov telescope between 2010 and 2018. The central source VER J1745–290, consistent with the position of Sagittarius A*, is detected at a significance of 38 standard deviations above the background level (38 σ ), and we report its spectrum and light curve. Its differential spectrum is consistent with a power law with exponential cutoff, with a spectral index of , a flux normalization at 5.3 TeV of TeV −1 cm −2 s −1 , and cutoff energy of TeV. We also present results on the diffuse emission near the GC, obtained by combining data from multiple regions along the GC ridge, which yield a cumulative significance of 9.5 σ . The diffuse GC ridge spectrum is best fit by a power law with a hard index of 2.19 ± 0.20, showing no evidence of a cutoff up to 40 TeV. This strengthens the evidence for a potential accelerator of PeV cosmic rays being present in the GC. We also provide spectra of the other sources in our field of view with significant detections, composite SNR G0.9+0.1, and HESS J1746–285.