Data di Pubblicazione:
2009
Citazione:
Stellar and total baryon mass fractions in groups and clusters since redshift 1 / S. Giodini, D. Pierini, A. Finoguenov, G.W. Pratt, H. Boehringer, A. Leauthaud, GUZZO LUIGI, H. Aussel, M. Bolzonella, P. Capak, M. Elvis, G. Hasinger, O. Ilbert, J.S. Kartaltepe, A.M. Koekemoer, S.J. Lilly, R. Massey, H.J. Mccracken, J. Rhodes, M. Salvato, D.B. Sanders, N.Z. Scoville, S. Sasaki, V. Smolcic, Y. Taniguchi, D. Thompson. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 703:1(2009), pp. 982-993. [10.1088/0004-637X/703/1/982]
Abstract:
We investigate if the discrepancy between estimates of the total baryon mass fraction obtained from observations of the cosmic microwave background (CMB) and of galaxy groups/clusters persists when a large sample of groups is considered. To this purpose, 91 candidate X-ray groups/poor clusters at redshift 0.1 <= z <= 1 are selected from the COSMOS 2 deg(2) survey, based only on their X-ray luminosity and extent. This sample is complemented by 27 nearby clusters with a robust, analogous determination of the total and stellar mass inside R(500). The total sample of 118 groups and clusters with z <= 1 spans a range in M(500) of similar to 10(13)-10(15) M(circle dot). We find that the stellar mass fraction associated with galaxies at R(500) decreases with increasing total mass as M(500)(-0.37+/-0.04), independent of redshift. Estimating the total gas mass fraction from a recently derived, high-quality scaling relation, the total baryon mass fraction (f(500)(stars+gas) = f(500)(stars) + f(500)(gas)) is found to increase by similar to 25%, when M(500) increases from < M > = 5 x 10(13) M(circle dot) to < M > = 7 x 10(14)M(circle dot). After consideration of a plausible contribution due to intracluster light (11%-22% of the total stellar mass) and gas depletion through the hierarchical assembly process (10% of the gas mass), the estimated values of the total baryon mass fraction are still lower than the latest CMB measure of the same quantity (WMAP5), at a significance level of 3.3 sigma for groups of < M > = 5 x 10(13) M(circle dot). The discrepancy decreases toward higher total masses, such that it is 1 sigma at < M > = 7 x 10(14) M(circle dot). We discuss this result in terms of nongravitational processes such as feedback and filamentary heating.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
cosmological parameters; cosmology: observations; diffuse radiation; galaxies: clusters: general; galaxies: stellar content; X-rays: galaxies: clusters
Elenco autori:
S. Giodini, D. Pierini, A. Finoguenov, G.W. Pratt, H. Boehringer, A. Leauthaud, L. Guzzo, H. Aussel, M. Bolzonella, P. Capak, M. Elvis, G. Hasinger, O. Ilbert, J.S. Kartaltepe, A.M. Koekemoer, S.J. Lilly, R. Massey, H.J. Mccracken, J. Rhodes, M. Salvato, D.B. Sanders, N.Z. Scoville, S. Sasaki, V. Smolcic, Y. Taniguchi, D. Thompson
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