TY - JOUR
T1 - A young massive stellar population around the intermediate-mass black hole ESO 243-49 HLX-1
AU - Farrell, S. A.
AU - Servillat, M.
AU - Pforr, J.
AU - MacCarone, T. J.
AU - Knigge, C.
AU - Godet, O.
AU - Maraston, C.
AU - Webb, N. A.
AU - Barret, D.
AU - Gosling, A. J.
AU - Belmont, R.
AU - Wiersema, K.
PY - 2012/3/1
Y1 - 2012/3/1
N2 - We present Hubble Space Telescope and simultaneous Swift X-ray Telescope observations of the strongest candidate intermediate-mass black hole (IMBH) ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disk models, but is well described by a model comprised of an irradiated accretion disk plus a 106 M stellar population. The age of the population cannot be uniquely constrained, with both young and old stellar populations allowed. However, the old solution requires excessive disk reprocessing and an extremely small disk, so we favor the young solution (13Myr). In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy suggest that a gas-rich minor merger may have taken place less than 200Myr ago. Such a merger event would explain the presence of the IMBH and the young stellar population.
AB - We present Hubble Space Telescope and simultaneous Swift X-ray Telescope observations of the strongest candidate intermediate-mass black hole (IMBH) ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disk models, but is well described by a model comprised of an irradiated accretion disk plus a 106 M stellar population. The age of the population cannot be uniquely constrained, with both young and old stellar populations allowed. However, the old solution requires excessive disk reprocessing and an extremely small disk, so we favor the young solution (13Myr). In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy suggest that a gas-rich minor merger may have taken place less than 200Myr ago. Such a merger event would explain the presence of the IMBH and the young stellar population.
KW - X-rays: binaries
KW - X-rays: individual (ESO 243-49 HLX-1)
KW - accretion, accretion disks
KW - galaxies: interactions
KW - galaxies: star clusters: general
KW - globular clusters: general
UR - http://www.scopus.com/inward/record.url?scp=84857579088&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/747/1/L13
DO - 10.1088/2041-8205/747/1/L13
M3 - Article
AN - SCOPUS:84857579088
SN - 2041-8205
VL - 747
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L13
ER -