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http://hdl.handle.net/20.500.12386/29395
Title: | The very faint hard state of the persistent neutron star X-ray binary SLX 1737-282 near the Galactic Centre | Authors: | Armas Padilla, M. PONTI, GABRIELE De Marco, B. Muñoz-Darias, T. Haberl, F. |
Issue Date: | 2018 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 473 | Issue: | 3 | First Page: | 3789 | Abstract: | We report on a detailed study of the spectral and temporal properties of the neutron star low-mass X-ray binary SLX 1737-282, which is located only ∼1° away from Sgr A*. The system is expected to have a short orbital period, even within the ultracompact regime, given its persistent nature at low X-ray luminosities and the long duration thermonuclear burst that it has displayed. We have analysed a Suzaku (18 ks) observation and an XMM-Newton (39 ks) observation taken 7 yr apart. We infer (0.5-10 keV) X-ray luminosities in the range of 3-6 × 10<SUP>35</SUP>ergs<SUP>-1</SUP>, in agreement with previous findings. The spectra are well described by a relatively cool (kT<SUB>bb</SUB> = 0.5 keV) blackbody component plus a Comptonized emission component with Γ ∼ 1.5-1.7. These values are consistent with the source being in a faint hard state, as confirmed by the ∼20 per cent fractional root-mean-square amplitude of the fast variability (0.1-7 Hz) inferred from the XMM-Newton data. The electron temperature of the corona is ≳7 keV for the Suzaku observation, but it is measured to be as low as ∼2 keV in the XMM-Newton data at higher flux. The latter is significantly lower than expected for systems in the hard state. We searched for X-ray pulsations and imposed an upper limit to their semi-amplitude of 2 per cent (0.001-7 Hz). Finally, we investigated the origin of the low-frequency variability emission present in the XMM-Newton data and ruled out an absorption dip origin. This constraint the orbital inclination of the system to ≲65° unless the orbital period is longer than 11 h (i.e. the length of the XMM-Newton observation). | URI: | http://hdl.handle.net/20.500.12386/29395 | URL: | https://academic.oup.com/mnras/article/473/3/3789/4265368 | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stx2538 | Bibcode ADS: | 2018MNRAS.473.3789A | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
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1706.01479.pdf | preprint | 582.54 kB | Adobe PDF | View/Open |
stx2538.pdf | pdf editoriale | 593.6 kB | Adobe PDF | View/Open |
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