TY - JOUR
T1 - The baryon budget on the galaxy group/cluster boundary
AU - Sanderson, A.J.R.
AU - O'Sullivan, E.
AU - Ponman, T.J.
AU - Gonzalez, A.H.
AU - Sivanandam, S.
AU - Zabludoff, A.I.
AU - Zaritsky, D.
N1 - Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/3/11
Y1 - 2013/3/11
N2 - We present a study of the hot gas and stellar content of five optically selected poor galaxy clusters, including a full accounting of the contribution from intracluster light (ICL) and a combined hot gas and hydrostatic X-ray mass analysis with XMM-Newton observations. We find weighted mean stellar (including ICL), gas and total baryon mass fractions within r of 0.026 ± 0.003, 0.070 ± 0.005 and 0.096 ± 0.006, respectively, at a corresponding weighted mean M of (1.08) × 10 M. Even when accounting for the intracluster stars, four out of five clusters show evidence for a substantial baryon deficit within r, with baryon fractions (f) between 50 ± 6 and 59 ± 8 per cent of the universal mean level (i.e. Ω/Ω), the remaining cluster having f = 75±11 per cent. For the three clusters where we can trace the hot halo to r we find no evidence for a steepening of the gas density profile in the outskirts with respect to a power law, as seen in more massive clusters. We find that in all cases, the X-ray mass measurements are larger than those originally published on the basis of the galaxy velocity dispersion (σ) and an assumed σ-M relation, by a factor of 1.7-5.7. Despite these increased masses, the stellar fractions (in the range 0.016-0.034, within r) remain consistent with the trend with mass published by Gonzalez et al., from which our sample is drawn.
AB - We present a study of the hot gas and stellar content of five optically selected poor galaxy clusters, including a full accounting of the contribution from intracluster light (ICL) and a combined hot gas and hydrostatic X-ray mass analysis with XMM-Newton observations. We find weighted mean stellar (including ICL), gas and total baryon mass fractions within r of 0.026 ± 0.003, 0.070 ± 0.005 and 0.096 ± 0.006, respectively, at a corresponding weighted mean M of (1.08) × 10 M. Even when accounting for the intracluster stars, four out of five clusters show evidence for a substantial baryon deficit within r, with baryon fractions (f) between 50 ± 6 and 59 ± 8 per cent of the universal mean level (i.e. Ω/Ω), the remaining cluster having f = 75±11 per cent. For the three clusters where we can trace the hot halo to r we find no evidence for a steepening of the gas density profile in the outskirts with respect to a power law, as seen in more massive clusters. We find that in all cases, the X-ray mass measurements are larger than those originally published on the basis of the galaxy velocity dispersion (σ) and an assumed σ-M relation, by a factor of 1.7-5.7. Despite these increased masses, the stellar fractions (in the range 0.016-0.034, within r) remain consistent with the trend with mass published by Gonzalez et al., from which our sample is drawn.
UR - http://www.scopus.com/inward/record.url?partnerID=yv4JPVwI&eid=2-s2.0-84874126369&md5=ae9b0e3b1463d2b174c00f68de1c853f
U2 - 10.1093/mnras/sts586
DO - 10.1093/mnras/sts586
M3 - Article
AN - SCOPUS:84874126369
SN - 0035-8711
VL - 429
SP - 3288
EP - 3304
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
IS - 4
ER -