Detection of Reflection Features in the Neutron Star Low-Mass X-ray Binary Serpens X-1 with NICER
| Autor: | Ludlam, R. M., Miller, J. M., Arzoumanian, Z., Bult, P. M., Cackett, E. M., Chakrabarty, D., Dauser, T., Enoto, T., Fabian, A. C., Garcia, J. A., Gendreau, K. C., Guillot, S., Homan, J., Jaisawal, G. K., Keek, L., La Marr, B., Malacaria, C., Markwardt, C. B., Steiner, J. F., Strohmayer, T. E. |
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| Rok vydání: | 2018 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/2041-8213/aabee6 |
| Popis: | We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in addition to the signature broad, asymmetric Fe K line. We confirm the presence of these lines by comparing the NICER data to archival observations with XMM-Newton/RGS and NuSTAR. Both features originate close to the innermost stable circular orbit (ISCO). When modeling the lines with the relativistic line model RELLINE, we find the Fe L blend requires an inner disk radius of $1.4_{-0.1}^{+0.2}$ $R_{\mathrm{ISCO}}$ and Fe K is at $1.03_{-0.03}^{+0.13}$ $R_{\mathrm{ISCO}}$ (errors quoted at 90%). This corresponds to a position of $17.3_{-1.2}^{+2.5}$ km and $12.7_{-0.4}^{+1.6}$ km for a canonical neutron star mass ($M_{\mathrm{NS}}=1.4\ M_{\odot}$) and dimensionless spin value of $a=0$. Additionally, we employ a new version of the RELXILL model tailored for neutron stars and determine that these features arise from a dense disk and supersolar Fe abundance. Comment: 6 pages, 4 figures, 1 table, accepted for publication in ApJL |
| Databáze: | arXiv |
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