Do blue galaxy-clusters have hot intracluster gas?
| Autor: | Misato, Rana, Toba, Yoshiki, Ota, Naomi, Yamamoto, Naoaki, Kodama, Tadayuki, Okabe, Nobuhiro, Oguri, Masamune, Mitsuishi, Ikuyuki |
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| Rok vydání: | 2022 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/pasj/psac002 |
| Popis: | We present herein a systematic X-ray analysis of blue galaxy-clusters at $z=0.84$ discovered by the Subaru telescope. The sample consisted of 43 clusters identified by combining red-sequence and blue-cloud surveys, covering a wide range of emitter fractions (i.e., 0.3--0.8). The spatial extent of the over-density region of emitter galaxies was approximately 1~Mpc in radius. The average cluster mass was estimated as $0.6 (<1.5)\times10^{14}~{\rm M_\odot}$ from the stacked weak-lensing measurement. We analyzed the XMM-Newton archival data, and measured the X-ray luminosity of the hot intracluster medium. As a result, diffuse X-ray emission was marginally detected in 14 clusters, yielding an average luminosity of $5\times 10^{42}~{\rm erg\,s^{-1}}$. On the contrary, it was not significant in 29 clusters. The blue clusters were significantly fainter than the red-dominated clusters, and the X-ray luminosity did not show any meaningful correlation either with emitter fraction or richness. The X-ray surface brightness was low, but the amount of gas mass was estimated to be comparable to that observed in the $10^{13-14}~{\rm M_{\odot}}$ cluster. Based on the results, we suggest that the blue clusters are at the early formation stage, and the gas is yet to be compressed and heated up to produce appreciable X-rays. Follow-up spectroscopic measurements are essential to clarify the dynamical status and co-evolution of galaxies and hot gas in the blue clusters. Comment: 9 pages, 7 figures, PASJ accepted |
| Databáze: | arXiv |
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