SRG/ART-XC and NuSTAR observations of the X-ray pulsar GRO J1008-57 in the lowest luminosity state
| Autor: | V. Arefiev, A. Tkachenko, S. Molkov, I. Lapshov, Victor Doroshenko, Alexander A. Lutovinov, M. N. Pavlinsky, Alexander A. Mushtukov, Sergey S. Tsygankov |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Spectral shape analysis
Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences High mass x-ray binary stars Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Neutron stars law.invention Luminosity Telescope Pulsar law Astrophysics::Solar and Stellar Astrophysics Pulsars Astrophysics::Galaxy Astrophysics High Energy Astrophysical Phenomena (astro-ph.HE) Physics Accretion (meteorology) Astronomy and Astrophysics Neutron star Orders of magnitude (time) Space and Planetary Science 1306 1108 733 Astrophysics - High Energy Astrophysical Phenomena X-ray pulsar |
| Zdroj: | The Astrophysical Journal, 912(1) |
| Popis: | We report results of the first broadband observation of the transient X-ray pulsar GRO J1008-57 performed in the quiescent state. Observations were conducted quasi-simultaneously with the Mikhail Pavlinsky ART-XC telescope on board SRG and NuSTAR right before the beginning of a Type I outburst. GRO J1008-57 was detected in the state with the lowest observed luminosity around several $\times 10^{34}$ erg s$^{-1}$ and consequently accreting from the cold disk. Timing analysis allowed to significantly detect pulsations during this state for the first time. The observed pulsed fraction of about 20\% is, however, almost three times lower than in brighter states when the accretion proceeds through the standard disk. We traced the evolution of the broadband spectrum of the source on a scale of three orders of magnitude in luminosity and found that at the lowest luminosities the spectrum transforms into the double-hump structure similarly to other X-ray pulsars accreting at low luminosities (X Persei, GX 304-1, A0535+262) reinforcing conclusion that this spectral shape is typical for these objects. 8 pages, 5 figures, accepted to ApJ |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|