Radio Emission Associated with the Ulx in Holmberg Ii
نویسندگان
چکیده
We report the detection of radio emission coincident with the ultraluminous X-ray source (ULX) in Holmberg II. The radio emission is diffuse and resolved, covering an area ∼ 60 × 40 pc in extent and well-matched to the recently discovered He ii nebula surrounding the X-ray source. Comparison of the radio and optical properties of this extended radio emission argue against its association with either an H ii region or supernova remnant. This is additional evidence that this ULX is not powered by a stellar-mass object whose emission is relativistically beamed towards the observer, and thus is either a super-Eddington source or intermediate mass black hole as suggested by optical observations. Implications of this result to future and existing radio studies of ULXs are discussed. Subject headings: galaxies: individual (Holmberg II) – stars: individual (Holmberg II X-1) – X-rays: galaxies – radio continuum: galaxies
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