Abstract
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 r500 of 0.026 ± 0.003, 0.070 ± 0.005 and 0.096 ± 0.006, respectively, at a corresponding weighted mean M500 of (1.08-0.18+0.21) × 1014 M⊙. Even when accounting for the intracluster stars, four out of five clusters show evidence for a substantial baryon deficit within r500, with baryon fractions (fb) between 50 ± 6 and 59 ± 8 per cent of the universal mean level (i.e. Ωb/Ωm), the remaining cluster having fb = 75±11 per cent. For the three clusters where we can trace the hot halo to r500 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-M500 relation, by a factor of 1.7-5.7. Despite these increased masses, the stellar fractions (in the range 0.016-0.034, within r500) remain consistent with the trend with mass published by Gonzalez et al., from which our sample is drawn.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3288-3304 |
| Number of pages | 17 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 429 |
| Issue number | 4 |
| DOIs | |
| State | Published - Mar 11 2013 |
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Keywords
- Cosmology: observations -X-rays: galaxies: clusters
- Galaxies: clusters: general
- Galaxies: evolution
- Galaxies: stellar content
ASJC Scopus subject areas
- Space and Planetary Science
- Astronomy and Astrophysics
Cite this
The baryon budget on the galaxy group/cluster boundary. / Sanderson, Alastair J R; O'Sullivan, Ewan; Ponman, Trevor J.; Gonzalez, Anthony H.; Sivanandam, Suresh; Zabludoff, Ann I; Zaritsky, Dennis F.
In: Monthly Notices of the Royal Astronomical Society, Vol. 429, No. 4, 11.03.2013, p. 3288-3304.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The baryon budget on the galaxy group/cluster boundary
AU - Sanderson, Alastair J R
AU - O'Sullivan, Ewan
AU - Ponman, Trevor J.
AU - Gonzalez, Anthony H.
AU - Sivanandam, Suresh
AU - Zabludoff, Ann I
AU - Zaritsky, Dennis F
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 r500 of 0.026 ± 0.003, 0.070 ± 0.005 and 0.096 ± 0.006, respectively, at a corresponding weighted mean M500 of (1.08-0.18+0.21) × 1014 M⊙. Even when accounting for the intracluster stars, four out of five clusters show evidence for a substantial baryon deficit within r500, with baryon fractions (fb) between 50 ± 6 and 59 ± 8 per cent of the universal mean level (i.e. Ωb/Ωm), the remaining cluster having fb = 75±11 per cent. For the three clusters where we can trace the hot halo to r500 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-M500 relation, by a factor of 1.7-5.7. Despite these increased masses, the stellar fractions (in the range 0.016-0.034, within r500) 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 r500 of 0.026 ± 0.003, 0.070 ± 0.005 and 0.096 ± 0.006, respectively, at a corresponding weighted mean M500 of (1.08-0.18+0.21) × 1014 M⊙. Even when accounting for the intracluster stars, four out of five clusters show evidence for a substantial baryon deficit within r500, with baryon fractions (fb) between 50 ± 6 and 59 ± 8 per cent of the universal mean level (i.e. Ωb/Ωm), the remaining cluster having fb = 75±11 per cent. For the three clusters where we can trace the hot halo to r500 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-M500 relation, by a factor of 1.7-5.7. Despite these increased masses, the stellar fractions (in the range 0.016-0.034, within r500) remain consistent with the trend with mass published by Gonzalez et al., from which our sample is drawn.
KW - Cosmology: observations -X-rays: galaxies: clusters
KW - Galaxies: clusters: general
KW - Galaxies: evolution
KW - Galaxies: stellar content
UR - http://www.scopus.com/inward/record.url?scp=84874126369&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84874126369&partnerID=8YFLogxK
U2 - 10.1093/mnras/sts586
DO - 10.1093/mnras/sts586
M3 - Article
AN - SCOPUS:84874126369
VL - 429
SP - 3288
EP - 3304
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -