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| Natura: | Preprint |
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2022
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| Accesso online: | https://arxiv.org/abs/2205.05204 |
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| _version_ | 1866908443263107072 |
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| author | Vinokurov, A. Atapin, K. Bordoloi, O. P. Sarkisyan, A. Kashyap, U. Chakraborty, M. Rahna, P. T. Kostenkov, A. Solovyeva, Y. Fabrika, S. Safonova, M. Gogoi, R. Sutaria, F. Murthy, J. |
| author_facet | Vinokurov, A. Atapin, K. Bordoloi, O. P. Sarkisyan, A. Kashyap, U. Chakraborty, M. Rahna, P. T. Kostenkov, A. Solovyeva, Y. Fabrika, S. Safonova, M. Gogoi, R. Sutaria, F. Murthy, J. |
| contents | We present the results of 8 epochs of simultaneous UV and X-ray observations of the highly variable ultraluminous X-ray source (ULX) Holmberg II X-1 with AstroSat -- Indian multiwavelength space satellite. During the entire observation period from late 2016 to early 2020, Holmberg II X-1 showed a moderate X-ray luminosity of $8\times10^{39}$ erg/s and a hard power-law spectrum with $Γ\lesssim 1.9$. Due to low variability of the object in X-rays (by a factor 1.5) and insignificant variability in the UV range (upper limit $\approx25$%) we could not find reliable correlation between flux changes in these ranges. Inside each particular observation, the X-ray variability amplitude is higher, it reaches a factor of 2-3 respect to the mean level at the time scales of $\sim10$ ks or even shorter. We discussed our results in terms of three models of a heated donor star, a heated disk and a heated wind, and estimated the lower limit to the variability which would allow to reject at least part of them. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2205_05204 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Simultaneous X-ray/UV observations of ultraluminous X-ray source Holmberg II X-1 with Indian space mission AstroSat Vinokurov, A. Atapin, K. Bordoloi, O. P. Sarkisyan, A. Kashyap, U. Chakraborty, M. Rahna, P. T. Kostenkov, A. Solovyeva, Y. Fabrika, S. Safonova, M. Gogoi, R. Sutaria, F. Murthy, J. High Energy Astrophysical Phenomena We present the results of 8 epochs of simultaneous UV and X-ray observations of the highly variable ultraluminous X-ray source (ULX) Holmberg II X-1 with AstroSat -- Indian multiwavelength space satellite. During the entire observation period from late 2016 to early 2020, Holmberg II X-1 showed a moderate X-ray luminosity of $8\times10^{39}$ erg/s and a hard power-law spectrum with $Γ\lesssim 1.9$. Due to low variability of the object in X-rays (by a factor 1.5) and insignificant variability in the UV range (upper limit $\approx25$%) we could not find reliable correlation between flux changes in these ranges. Inside each particular observation, the X-ray variability amplitude is higher, it reaches a factor of 2-3 respect to the mean level at the time scales of $\sim10$ ks or even shorter. We discussed our results in terms of three models of a heated donor star, a heated disk and a heated wind, and estimated the lower limit to the variability which would allow to reject at least part of them. |
| title | Simultaneous X-ray/UV observations of ultraluminous X-ray source Holmberg II X-1 with Indian space mission AstroSat |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2205.05204 |