MAXI and NuSTAR Observations of the Faint X-Ray Transient MAXI J1848-015 in the GLIMPSE-C01 Cluster
| Autor: | Sean N. Pike, Hitoshi Negoro, John A. Tomsick, Matteo Bachetti, McKinley Brumback, Riley M. T. Connors, Javier A. García, Brian Grefenstette, Jeremy Hare, Fiona A. Harrison, Amruta Jaodand, R. M. Ludlam, Guglielmo Mastroserio, Tatehiro Mihara, Megumi Shidatsu, Mutsumi Sugizaki, Ryohei Takagi |
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| Přispěvatelé: | ITA, USA, JPN |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Space and Planetary Science Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics - High Energy Astrophysical Phenomena Astrophysics::Galaxy Astrophysics |
| Popis: | We present the results of MAXI monitoring and two NuSTAR observations of the recently discovered faint X-ray transient MAXI J1848-015. Analysis of the MAXI light-curve shows that the source underwent a rapid flux increase beginning on 2020 December 20, followed by a rapid decrease in flux after only $\sim5$ days. NuSTAR observations reveal that the source transitioned from a bright soft state with unabsorbed, bolometric ($0.1$-$100$ keV) flux $F=6.9 \pm 0.1 \times 10^{-10}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$, to a low hard state with flux $F=2.85 \pm 0.04 \times 10^{-10}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$. Given a distance of $3.3$ kpc, inferred via association of the source with the GLIMPSE-C01 cluster, these fluxes correspond to an Eddington fraction of order $10^{-3}$ for an accreting neutron star of mass $M=1.4M_\odot$, or even lower for a more massive accretor. However, the source spectra exhibit strong relativistic reflection features, indicating the presence of an accretion disk which extends close to the accretor, for which we measure a high spin, $a=0.967\pm0.013$. In addition to a change in flux and spectral shape, we find evidence for other changes between the soft and hard states, including moderate disk truncation with the inner disk radius increasing from $R_\mathrm{in}\approx3\,R_\mathrm{g}$ to $R_\mathrm{in}\approx8\,R_\mathrm{g}$, narrow Fe emission whose centroid decreases from $6.8\pm0.1$ keV to $6.3 \pm 0.1$ keV, and an increase in low-frequency ($10^{-3}$-$10^{-1}$ Hz) variability. Due to the high spin we conclude that the source is likely to be a black hole rather than a neutron star, and we discuss physical interpretations of the low apparent luminosity as well as the narrow Fe emission. 19 pages, 9 figures, 3 tables. Accepted for publication in ApJ |
| Databáze: | OpenAIRE |
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