A multi-wavelength investigation of PSR J2229+6114 and its pulsar wind nebula in the radio, X-ray, and gamma-ray bands

• Main Authors: Pope, I, Mori, K, Abdelmaguid, M, Gelfand, J. D, Reynolds, S. P, Safi-Harb, S, Hailey, C. J, An, H, Collaboration, VERITAS, :, Bangale, P, Batista, P, Benbow, W, Buckley, J. H, Capasso, M, Christiansen, J. L, Chromey, A. J, Falcone, A, Feng, Q, Finley, J. P, Foote, G. M, Gallagher, G, Hanlon, W. F, Hanna, D, Hervet, O, Holder, J, Humensky, T. B, Jin, W, Kaaret, P, Kertzman, M, Kieda, D, Kleiner, T. K, Korzoun, N, Krennrich, F, Kumar, S, Lang, M. J, Maier, G, McGrath, C. E, Mooney, C. L, Moriarty, P, Mukherjee, R, O'Brien, S, Ong, R. A, Park, N, Patel, S. R, Pfrang, K, Pohl, M, Pueschel, E, Quinn, J, Ragan, K, Reynolds, P. T, Roache, E, Sadeh, I, Saha, L, Sembroski, G. H, Tak, D, Tucci, J. V, Weinstein, A, Williams, D. A, Woo, J
• Format: Journal Article
• Language: English
• Published: 06.10.2023
• Subjects: Physics - High Energy Astrophysical Phenomena
• DOI: 10.48550/arxiv.2310.04512

G106.3$+$2.7, commonly considered a composite supernova remnant (SNR), is characterized by a boomerang-shaped pulsar wind nebula (PWN) and two distinct ("head" & "tail") regions in the radio band. A discovery of very-high-energy (VHE) gamma-ray emission ($E_\gamma > 100$ GeV) followed by the recent detection of ultra-high-energy (UHE) gamma-ray emission ($E_\gamma > 100$ TeV) from the tail region suggests that G106.3$+$2.7 is a PeVatron candidate. We present a comprehensive multi-wavelength study of the Boomerang PWN (100" around PSR J2229+6114) using archival radio and Chandra data obtained from two decades ago, a new NuSTAR X-ray observation from 2020, and upper limits on gamma-ray fluxes obtained by Fermi and VERITAS observatories. The NuSTAR observation allowed us to detect a 51.67 ms spin period from the pulsar PSR J2229+6114 and the PWN emission characterized by a power-law model with $\Gamma = 1.52\pm0.06$ up to 20 keV. Contrary to the previous radio study by Kothes et al. 2006, we prefer a much lower PWN B-field ($B\sim3$ $\mu$G) and larger distance ($d \sim 8$ kpc) based on (1) the non-varying X-ray flux over the last two decades, (2) the energy-dependent X-ray PWN size resulting from synchrotron burn-off and (3) the multi-wavelength spectral energy distribution (SED) data. Our SED model suggests that the PWN is currently re-expanding after being compressed by the SNR reverse shock $\sim 1000$ years ago. In this case, the head region should be formed by GeV--TeV electrons injected earlier by the pulsar propagating into the low density environment.