2011/05/31 by Nanda Rea, Diego F. Torres · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Absorption (acoustics) #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Binary number #Earth Systems and Cosmic Evolution #Flux (metallurgy) #High energy #Intermediate state #Limit (mathematics) #Photon #Pulsar #SIGNAL (programming language) #Spectral line #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1088/2041-8205/737/1/l12
5 pages, 4 figures; ApJ Letter in press
arxiv created 2011/07/07 · openalex publication_date 2011/07/20 · arxiv updated 2015/05/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report on a 40 ks Chandra observation of the TeV emitting high-mass X-ray binary HESS J0632+057 performed in 2011 February during a high state of X-ray and TeV activity. We have used the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. Furthermore, we compare the emission of the source during this high state, with its X-ray properties during a low state of emission, caught by a 47 ks XMM-Newton observation on 2007 September. We did not find any periodic or quasi-periodic signal in any of the two observations. We derived an average pulsed fraction 3σ upper limit for the presence of a periodic signal of ≲35% and 25% during the low and high emission states, respectively (although this limit is strongly dependent on the frequency and the energy band). Using the best X-ray spectra derived to date for HESS J0632+057, we found evidence for a significant spectral change between the low and high X-ray emission states, with the absorption value and the photon index varying between N H ≃ (2.1–4.3) × 10 21 cm −2 and Γ ≃ 1.18–1.61. In contrast to what has been observed in other TeV binaries, it seems that in this source the higher the flux, the softer the X-ray spectrum.