Multiband Counterparts of Two Eclipsing Ultraluminous X-Ray Sources in M 51
MNRAS 000,1{16 (2017) Preprint 5 November 2018 Compiled using MNRAS LATEX style file v3.0 Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51 R. Urquhart,1? R. Soria,2;1;3 H.M. Johnston,3 M.W. Pakull,4 C. Motch,4 A. Schwope,5 J.C.A. Miller-Jones1 and G.E. Anderson1 1International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845, Australia 2National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China 3Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, Sydney, NSW 2006, Australia 4Observatoire astronomique, Universit´ede Strasbourg, CNRS, UMR 7550, 11 rue de l'Universit´e,67000, Strasbourg, France 5Leibniz-Institut f¨urAstrophysik Potsdam, An der Sternwarte 16, 14482, Potsdam, Germany Accepted XXX. Received YYY; in original form ZZZ ABSTRACT We present the discovery and interpretation of ionized nebulae around two ultra- luminous X-ray sources in M 51; both sources share the rare property of show- ing X-ray eclipses by their companion stars, and are therefore prime targets for follow-up studies. Using archival Hubble Space Telescope images, we found an elon- gated, 100-pc-long emission-line structure associated with one X-ray source (CXOM51 J132940.0+471237; ULX-1 for simplicity), and a more circular, ionized nebula at the location of the second source (CXOM51 J132939.5+471244; ULX-2 for simplicity). We observed both nebulae with the Large Binocular Telescope's Multi-Object Double Spectrograph. From our analysis of the optical spectra, we argue that the gas in the ULX-1 bubble is shock-ionized, consistent with the effect of a jet with a kinetic power of ≈2 ×1039 erg s−1.
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