Concordance of X-ray cluster data with big bang nucleosynthesis in mixed dark matter models

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Astrophysical Journal

DOI:https://doi.org/10.1086/304059· OSTI ID:538391

Strickland, R W ^[1]; Schramm, D N ^[1]

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1. University of Chicago, Chicago, Illinois 60637 (United States)

If the hot, X-ray-emitting gas in rich clusters forms a fair sample of the universe as in cold dark matter (CDM) models and the universe is at the critical density {Omega}{sub T}=1, then the data appear to imply a baryon fraction {Omega}{sub b,X} ({Omega}{sub b,X}{equivalent_to}{Omega}{sub b} derived from X-ray cluster data), larger than that predicted by big bang nucleosynthesis (BBN). While other systematic effects such as clumping can lower {Omega}{sub b,X}, in this paper we use an elementary analysis to show that a simple admixture of hot dark matter (HDM; low-mass neutrinos) with CDM to yield mixed dark matter shifts {Omega}{sub b,X} down so that significant overlap with {Omega}{sub b} from BBN can occur for H{sub 0}{approx_lt}73kms{sup {minus}1}Mpc{sup {minus}1}, even without invoking the possible aforementioned effects. The overlap interval is slightly larger for lower mass neutrinos since fewer of them cluster on the scale of the hot X-ray gas. We illustrate this result quantitatively in terms of a simple isothermal model. More realistic velocity dispersion profiles, with less centrally peaked density profiles, imply that fewer neutrinos are trapped and thus further increase the interval of overlap. {copyright} {ital 1997} {ital The American Astronomical Society}

• OSTI ID: 538391
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 481; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COSMIC NEUTRINOS
COSMIC PHOTONS
COSMOLOGICAL MODELS
COSMOLOGY
ELEMENT ABUNDANCE
GALAXY CLUSTERS
NONLUMINOUS MATTER
NUCLEOSYNTHESIS
REST MASS