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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2018

Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51

R. Urquhart
  • Fonction : Auteur
R. Soria
  • Fonction : Auteur
H.M. Johnston
  • Fonction : Auteur
A. Schwope
  • Fonction : Auteur
J.C.A. Miller-Jones
  • Fonction : Auteur
G.E. Anderson
  • Fonction : Auteur

Résumé

We present the discovery and interpretation of ionized nebulae around two ultraluminous X-ray sources in M 51; both sources share the rare property of showing 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 elongated, 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 × 10^39 erg s^−1. Additional X-ray photoionization may also be present, to explain the strength of high-ionization lines such as He ii λ4686 and [Ne v] λ3426. On the other hand, the emission lines from the ULX-2 bubble are typical for photoionization by normal O stars suggesting that the nebula is actually an H ii region not physically related to the ULX but is simply a chance alignment. From archival Very Large Array data, we also detect spatially extended, steep-spectrum radio emission at the location of the ULX-1 bubble (consistent with its jet origin), but no radio counterpart for ULX-2 (consistent with the lack of shock-ionized gas around that source).

Dates et versions

hal-01703712 , version 1 (08-02-2018)

Identifiants

Citer

R. Urquhart, R. Soria, H.M. Johnston, M.W. Pakull, C. Motch, et al.. Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51. Monthly Notices of the Royal Astronomical Society, 2018, 475 (3), pp.3561-3576. ⟨10.1093/mnras/sty014⟩. ⟨hal-01703712⟩
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