학술논문
Multi-Wavelength Observation Campaign of the TeV Gamma-Ray Binary HESS J0632+057 with NuSTAR, VERITAS, MDM, and Swift
Document Type
Working Paper
Author
Tokayer, Y. M.; An, H.; Halpern, J. P.; Kim, J.; Mori, K.; Hailey, C. J.; Adams, C. B.; Benbow, W.; Brill, A.; Buckley, J. H.; Capasso, M.; Errando, M.; Falcone, A.; Farrell, K. A; Foote, G. M; Fortson, L.; Furniss, A.; Gent, A.; Giuri, C.; Hanna, D.; Hassan, T.; Hervet, O.; Holder, J.; Hona, B.; Humensky, T. B.; Jin, W.; Kaaret, P.; Kertzman, M.; Kieda, D.; Lang, M. J.; Maier, G.; McGrath, C. E; Moriarty, P.; Mukherjee, R.; Nievas-Rosillo, M.; O'Brien, S.; Ong, R. A.; Otte, A. N.; Park, N.; Patel, S.; Pfrang, K.; Pohl, M.; Prado, R. R.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Ribeiro, D.; Roache, E.; Ryan, J. L.; Santander, M.; Schlenstedt, S.; Sembroski, G. H.; Weinstein, A.; Williams, D. A.; Williamson, T. J
Source
Subject
Language
Abstract
HESS J0632+057 belongs to a rare subclass of binary systems which emits gamma-rays above 100 GeV. It stands out for its distinctive high-energy light curve, which features a sharp ``primary'' peak and broader ``secondary'' peak. We present the results of contemporaneous observations by NuSTAR and VERITAS during the secondary peak between Dec. 2019 and Feb. 2020, when the orbital phase ($\phi$) is between 0.55 and 0.75. NuSTAR detected X-ray spectral evolution, while VERITAS detected TeV emission. We fit a leptonic wind-collision model to the multi-wavelength spectra data obtained over the four NuSTAR and VERITAS observations, constraining the pulsar spin-down luminosity and the magnetization parameter at the shock. Despite long-term monitoring of the source from Oct. 2019 to Mar. 2020, the MDM observatory did not detect significant variation in H$\alpha$ and H$\beta$ line equivalent widths, an expected signature of Be-disk interaction with the pulsar. Furthermore, fitting folded Swift-XRT light curve data with an intra-binary shock model constrained the orbital parameters, suggesting two orbital phases (at $\phi_D = 0.13$ and 0.37) where the pulsar crosses the Be-disk, as well as phases for the periastron ($\phi_0 = 0.30$) and inferior conjunction ($\phi_{\text{IFC}} = 0.75$). The broad-band X-ray spectra with Swift-XRT and NuSTAR allowed us to measure a higher neutral hydrogen column density at one of the predicted disk-passing phases.
Comment: 21 pages, 9 figures, accepted to ApJ
Comment: 21 pages, 9 figures, accepted to ApJ