Non-thermal pressure support in X-COP galaxy clusters
Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
03 January 2019
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| In: |
Astronomy and astrophysics
Year: 2019, Volume: 621 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201833324 |
| Online Access: | Verlag, Volltext: https://doi.org/10.1051/0004-6361/201833324
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| Author Notes: | D. Eckert, V. Ghirardini, S. Ettori, E. Rasia, V. Biffi, E. Pointecouteau, M. Rossetti, S. Molendi, F. Vazza, F. Gastaldello, M. Gaspari, S. De Grandi, S. Ghizzardi, H. Bourdin, C. Tchernin, and M. Roncarelli |
| Summary: | Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure support is necessary to understand the processes leading to the virialization of the gas within the potential well of the main halo and to calibrate the biases in hydrostatic mass estimates. We present high-quality measurements of hydrostatic masses and intracluster gas fraction out to the virial radius for a sample of 13 nearby clusters with available <i>XMM-Newton<i/> and <i>Planck<i/> data. We compare our hydrostatic gas fractions with the expected universal gas fraction to constrain the level of non-thermal pressure support. We find that hydrostatic masses require little correction and infer a median non-thermal pressure fraction of ∼6% and ∼10% at <i>R<i/><sub>500<sub/> and <i>R<i/><sub>200<sub/>, respectively. Our values are lower than the expectations of hydrodynamical simulations, possibly implying a faster thermalization of the gas. If instead we use the mass calibration adopted by the <i>Planck<i/> team, we find that the gas fraction of massive local systems implies a mass bias 1 − <i>b<i/> = 0.85 ± 0.05 for Sunyaev-Zeldovich-derived masses, with some evidence for a mass-dependent bias. Conversely, the high bias required to match <i>Planck<i/> cosmic microwave background and cluster count cosmology is excluded by the data at high significance, unless the most massive halos are missing a substantial fraction of their baryons. |
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| Item Description: | Gesehen am 19.08.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201833324 |