@article{8dab8950ea204452bdd02ccc2fd78e28,
title = "The complex evolution of the X-ray binary transient MAXI J1807+132 along the decay of its discovery outburst",
abstract = "MAXI J1807+132 is an X-ray transient discovered during the decay of an outburst in 2017. We present optical and X-ray monitoring of the source over more than 125 d, from outburst to quiescence. The outburst decay is characterized by the presence of several reflares with a quasi-periodic recurrence time of ∼6.5 d. We detect broad H and He emission lines during outburst, characteristic of transient low-mass X-ray binaries. These emission lines show strong variability from epoch to epoch and, in particular, during the early stages are found embedded into deep and very broad absorption features. The quiescent spectrum shows Hα in emission and no obvious signatures of the donor star. XMM-Newton and Swift spectra can be fitted with standard X-ray models for accreting black holes and neutron stars, although the obtained spectral parameters favour the latter scenario. Conversely, other observables such as the optical/X-ray flux ratio, the likely systemic velocity (γ ∼ −150 km s−1), and the reflares recurrence time suggest a black hole nature. We discuss all the above possibilities with emphasis on the strong similarities of MAXI J1807+132 with short orbital period systems.",
keywords = "Accretion, Accretion discs, Black hole physics, Stars: neutron, X-rays: binaries",
author = "F. Jim{\'e}nez-Ibarra and T. Mu{\~n}oz-Darias and {Armas Padilla}, M. and Russell, {D. M.} and J. Casares and Torres, {M. A.P.} and {Mata S{\'a}nchez}, D. and Jonker, {P. G.} and F. Lewis",
note = "Funding Information: We are grateful to the anonymous referee for useful comments and suggestions that have improved the paper. We acknowledge support by the Spanish MINECO under grant AYA2017-83216-P. This study is based on observations made with the Gran Telescopio Canarias (GTC), installed on the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias in the island of La Palma. The authors are thankful to the GTC team that carried out the Target of Opportunity (ToO) observations. We are thankful to Phil Charles, Nathalie Degenaar, Rudy Wijnands, and Tom Maccarone for useful discussion on the nature of the system. The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias. This study is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias with financial support from the UK Science and Technology Facilities Council. TM-D is supported by RYC-2015-18148. MAP{\textquoteright}s research is funded under the Juan de la Cierva Fellowship Programme (IJCI-2016-30867) from MINECO. MAPT acknowledges support via a Ram{\'o}n y Cajal Fellowship (RYC-2015-17854). DMS acknowledges support from the ERC under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement no. 715051; Spiders). MOLLY software developed by T. R. Marsh is gratefully acknowledged. The Faulkes Telescope Project is an education partner of LCO. The Faulkes Telescopes are maintained and operated by LCO. Funding Information: We are grateful to the anonymous referee for useful comments and suggestions that have improved the paper. We acknowledge support by the Spanish MINECO under grant AYA2017-83216-P. This study is based on observations made with the Gran Telescopio Canarias (GTC), installed on the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias in the island of La Palma. The authors are thankful to the GTC team that carried out the Target of Opportunity (ToO) observations. We are thankful to Phil Charles, Nathalie Degenaar, Rudy Wijnands, and Tom Maccarone for useful discussion on the nature of the system. The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias. This study is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias with financial support from the UK Science and Technology Facilities Council. TM-D is supported by RYC-2015-18148. MAP's research is funded under the Juan de la Cierva Fellowship Programme (IJCI-2016-30867) from MINECO. MAPT acknowledges support via a Ram{\'o}n y Cajal Fellowship (RYC-2015-17854). DMS acknowledges support from the ERC under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 715051; Spiders). MOLLY software developed by T. R. Marsh is gratefully acknowledged. The Faulkes Telescope Project is an education partner of LCO. The Faulkes Telescopes are maintained and operated by LCO. Publisher Copyright: {\textcopyright} 2018 The Author(s).",
year = "2019",
month = apr,
day = "1",
doi = "10.1093/mnras/sty3457",
language = "English (US)",
volume = "484",
pages = "2078--2088",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "2",
}