TY - JOUR
T1 - Composition of an emission line system in black hole host globular cluster RZ2109
AU - Steele, Matthew M.
AU - Zepf, Stephen E.
AU - Maccarone, Thomas J.
AU - Kundu, Arunav
AU - Rhode, Katherine L.
AU - Salzer, John J.
PY - 2014/4/20
Y1 - 2014/4/20
N2 - We present an analysis of optical spectra from the globular cluster RZ2109 in NGC 4472, which hosts the first unambiguous globular cluster black hole. We use these spectra to determine the elemental composition of the emission line system associated with this source, and to constrain the age and metallicity of the host globular cluster. For the emission line system of RZ2109, our analysis indicates the [O III] λ5007 equivalent width is 33.82 ± 0.39 Å and the Hβ equivalent width is 0.32 ± 0.32 Å, producing a formal [O III] λ5007/Hβ emission line ratio of 106 for a 3200 km s-1 measurement aperture covering the full velocity width of the [O III] λ5007 line. Within a narrower 600 km s-1 aperture covering the highest luminosity velocity structure in the line complex, we find [O III] λ5007/Hβ = 62. The measured [O III] λ5007/Hβ ratios are significantly higher than can be produced in radiative models of the emission line region with solar composition, and the confidence interval limits exclude all but models which have gas masses much larger than those for a single star. Therefore, we conclude that the region from which the [O III] λ5007 emission originates is hydrogen-depleted relative to solar composition gas. This finding is consistent with emission from an accretion-powered outflow driven by a hydrogen-depleted donor star, such as a white dwarf, being accreted onto a black hole.
AB - We present an analysis of optical spectra from the globular cluster RZ2109 in NGC 4472, which hosts the first unambiguous globular cluster black hole. We use these spectra to determine the elemental composition of the emission line system associated with this source, and to constrain the age and metallicity of the host globular cluster. For the emission line system of RZ2109, our analysis indicates the [O III] λ5007 equivalent width is 33.82 ± 0.39 Å and the Hβ equivalent width is 0.32 ± 0.32 Å, producing a formal [O III] λ5007/Hβ emission line ratio of 106 for a 3200 km s-1 measurement aperture covering the full velocity width of the [O III] λ5007 line. Within a narrower 600 km s-1 aperture covering the highest luminosity velocity structure in the line complex, we find [O III] λ5007/Hβ = 62. The measured [O III] λ5007/Hβ ratios are significantly higher than can be produced in radiative models of the emission line region with solar composition, and the confidence interval limits exclude all but models which have gas masses much larger than those for a single star. Therefore, we conclude that the region from which the [O III] λ5007 emission originates is hydrogen-depleted relative to solar composition gas. This finding is consistent with emission from an accretion-powered outflow driven by a hydrogen-depleted donor star, such as a white dwarf, being accreted onto a black hole.
KW - X-rays: binaries
KW - X-rays: galaxies: clusters
KW - galaxies: individual (NGC 4472)
KW - galaxies: star clusters: individual (NGC 4472)
KW - globular clusters: general
UR - http://www.scopus.com/inward/record.url?scp=84898004963&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/785/2/147
DO - 10.1088/0004-637X/785/2/147
M3 - Article
AN - SCOPUS:84898004963
SN - 0004-637X
VL - 785
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 147
ER -