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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2401.00727 |
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| _version_ | 1866913357089472512 |
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| author | Berg, Maureen van den Homan, Jeroen Heinke, Craig O. Pooley, David A. Wijnands, Rudy Bahramian, Arash Miller-Jones, James C. A. |
| author_facet | Berg, Maureen van den Homan, Jeroen Heinke, Craig O. Pooley, David A. Wijnands, Rudy Bahramian, Arash Miller-Jones, James C. A. |
| contents | We have analyzed Chandra and Suzaku observations of the globular cluster Terzan 6, made when the recurrent transient GRS 1747-312 was in quiescence. Our analysis reveals the presence of a second eclipsing, bursting neutron-star low-mass X-ray binary in the central regions of the cluster, in addition to GRS 1747-312. The new source, which we name Terzan 6 X2, is located only ~0.7 arcsec away from GRS 1747-312 in the 2021 Chandra images. The detection of a 5.14 ks-long eclipse in the light curve of X2 at a time not predicted by the ephemeris of GRS 1747-312 confirms that it is an unrelated source. Using the Suzaku light curve from 2009, which in addition to a type-I X-ray burst also showed an eclipse-like feature, we constrain the orbital period to be longer than 16.27 h. The 0.5-10 keV luminosities of X2 vary in the range of ~0.24-5.9x10^34 erg/s on time scales of months to years. We have identified a plausible optical counterpart of X2 in HST F606W and F814W images. This star varied by 2.7 mag in V_606 between epochs separated by years. In the cluster color-magnitude diagram, the variable counterpart lies in the blue-straggler region when it was optically bright, about 1.1-1.7 mag above the main-sequence turn-off. From the orbital period-density relation of Roche-lobe filling stars we find the mass-donor radius to be >0.8 Rsun. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_00727 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Discovery of a second eclipsing, bursting neutron-star low-mass X-ray binary in the globular cluster Terzan 6 Berg, Maureen van den Homan, Jeroen Heinke, Craig O. Pooley, David A. Wijnands, Rudy Bahramian, Arash Miller-Jones, James C. A. High Energy Astrophysical Phenomena We have analyzed Chandra and Suzaku observations of the globular cluster Terzan 6, made when the recurrent transient GRS 1747-312 was in quiescence. Our analysis reveals the presence of a second eclipsing, bursting neutron-star low-mass X-ray binary in the central regions of the cluster, in addition to GRS 1747-312. The new source, which we name Terzan 6 X2, is located only ~0.7 arcsec away from GRS 1747-312 in the 2021 Chandra images. The detection of a 5.14 ks-long eclipse in the light curve of X2 at a time not predicted by the ephemeris of GRS 1747-312 confirms that it is an unrelated source. Using the Suzaku light curve from 2009, which in addition to a type-I X-ray burst also showed an eclipse-like feature, we constrain the orbital period to be longer than 16.27 h. The 0.5-10 keV luminosities of X2 vary in the range of ~0.24-5.9x10^34 erg/s on time scales of months to years. We have identified a plausible optical counterpart of X2 in HST F606W and F814W images. This star varied by 2.7 mag in V_606 between epochs separated by years. In the cluster color-magnitude diagram, the variable counterpart lies in the blue-straggler region when it was optically bright, about 1.1-1.7 mag above the main-sequence turn-off. From the orbital period-density relation of Roche-lobe filling stars we find the mass-donor radius to be >0.8 Rsun. |
| title | Discovery of a second eclipsing, bursting neutron-star low-mass X-ray binary in the globular cluster Terzan 6 |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2401.00727 |