2017/03/02 by Iurii Sushch, Brian van Soelen
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Binary star #Flux (metallurgy) #Photon #Position (finance) #Position angle #Pulsar #Pulsars and Gravitational Waves Research #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/aa62ff
9 pages, 7 figures, 1 table. Accepted for publication in ApJ
arxiv created 2017/03/02 · openalex publication_date 2017/03/10 · openalex created_date 2017/03/16 · arxiv updated 2017/03/22 · openalex updated_date 2026/08/05
Abstract The observed TeV light curve from the γ -ray binary PSR B1259-63/LS 2883 shows a decrease in the flux at periastron that has not been fully explained by emission mechanisms alone. This observed decrease can, however, be explained by γγ absorption due to the stellar and disk photons. We calculate the γγ absorption in PSR B1259-63/LS 2883 taking into account photons from both the circumstellar disk and star, assuming that the γ -rays originate at the position of the pulsar. The γγ absorption due to the circumstellar disk photons produces a ≈14% decrease in the flux, and there is a total decrease of ≈52% (>1 TeV) within a few days before periastron, accompanied by a hardening of the γ -ray photon index. While the γγ absorption alone is not sufficient to explain the full complexity of the H.E.S.S. γ -ray light curve, it results in a significant decrease in the predicted flux, which is coincident with the observed decrease. In addition, we have calculated an upper limit on the γγ absorption, assuming that the emission is produced at the apex of the bow shock. Future observations with CTA during the 2021 periastron passage may be able to confine the location of the emission based on the degree of γγ absorption, as well as measure the hardening of the spectrum around periastron.