A joint SRG/eROSITA + ZTF search: Discovery of a 97-min period eclipsing cataclysmic variable with evidence of a brown dwarf secondary

Abstract

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Acknowledgement

This work is based on observations with eROSITA telescope onboard SRG observatory. The SRG observatory was built by Roskosmos in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI) in the framework of the Russian Federal Space Programme, with the participation of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The SRG/eROSITA X-ray telescope was built by a consortium of German Institutes led by MPE, and supported by DLR. The SRG spacecraft was designed, built, launched, and is operated by the Lavochkin Association and its subcontractors. The science data are downlinked via the Deep Space Network Antennae in Bear Lakes, Ussurijsk, and Baykonur, funded by Roskosmos. The eROSITA data used in this work were processed using the eSASS software system developed by the German eROSITA consortium and proprietary data reduction and analysis software developed by the Russian eROSITA Consortium.

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grants Numbers AST-1440341 and AST-2034437 and a collaboration, including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Centre at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant number 12540303 (PI: Graham).

We are grateful to the staffs of the Palomar and Keck Observatories for their work in helping us carry out our observations. We thank TÜBİTAK, the Space Research Institute of the Russian Academy of Sciences, the Kazan Federal University, and the Academy of Sciences of Tatarstan for their partial support in using RTT-150 (Russian–Turkish 1.5-m telescope in Antalya).

This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

This research made use of matplotlib, a python library for publication quality graphics (Hunter 2007); numpy (Harris et al. 2020); Astroquery (Ginsburg et al. 2019); astropy, a community-developed core python package for Astronomy (Astropy Collaboration et al. 2013, 2018); and the VizieR Catalogue access tool, CDS, Strasbourg, France. The authors wish to thank E. Kotze for making his Doppler tomography code, doptomog, public (Kotze, Potter & McBride 2015).

IG acknowledges support from Kazan Federal University. ACR acknowledges support from the National Science Foundation via an NSF Graduate Research Fellowship. The work of IB, MG, IKh, AS, PM, RG supported by the RSF grant number 23-12-00292. LY gratefully acknowledges discussions with G. Tovmassian. BG acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement no. 101020057). The authors thank the anonymous referee for their helpful comments and suggestions that improved the quality of the manuscript.

Data Availability

X-ray data analysed in this article were used with the permission of the Russian SRG/eROSITA consortium. The data will become publicly available as a part of the corresponding SRG/eROSITA data release along with the appropriate calibration information. The Keck/LRIS, DBSP, CHIMERA, and RTT-150 data underlying this article will be shared on reasonable request to the corresponding author. All other data are publicly available and can be accessed at the corresponding public archive servers.