dc.contributor.author Ruszkowski, M dc.contributor.author Yang, HYK dc.contributor.author Reynolds, CS dc.date.accessioned 2018-10-10T05:17:06Z dc.date.available 2018-10-10T05:17:06Z dc.date.issued 2018 dc.identifier.issn 0004-637X dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/283363 dc.description.abstract Cluster cool cores possess networks of line-emitting filaments. These filaments are thought to originate via uplift of cold gas from cluster centers by buoyant active galactic nuclei (AGN) bubbles, or via local thermal instability in the hot intracluster medium (ICM). Therefore, the filaments are either the signatures of AGN feedback or feeding of supermassive black holes. Despite being characterized by very short cooling times, the filaments are significant H$\alpha$ emitters, which suggests that some process continuously powers these structures. Many cool cores host diffuse radio mini halos and AGN injecting radio plasma, suggesting that cosmic rays (CRs) and magnetic fields are present in the ICM. We argue that the excitation of Alfv\'en waves by CR streaming, and the replenishment of CR energy via accretion onto the filaments of high plasma-$\beta$ ICM characterized by low CR pressure support, can provide the adequate amount of heating to power and sustain the emission from these filaments. This mechanism does not require the CRs to penetrate the filaments even if the filaments are magnetically isolated from the ambient ICM and it may operate irrespectively of whether the filaments are dredged up from the center or form in situ in the ICM. This picture is qualitatively consistent with non-thermal line ratios seen in the cold filaments. Future X-ray observations of the iron line complex with XARM, Lynx, or Athena could help to test this model by providing constraints on the amount of CRs in the hot plasma that is cooling and accreting onto the filaments. dc.publisher American Astronomical Society dc.rights Attribution 4.0 International dc.rights.uri https://creativecommons.org/licenses/by/4.0/ dc.title Powering of Hα Filaments by Cosmic Rays dc.type Article prism.issueIdentifier 1 prism.publicationDate 2018 prism.publicationName Astrophysical Journal prism.volume 858 dc.identifier.doi 10.17863/CAM.30731 dcterms.dateAccepted 2018-03-27 rioxxterms.versionofrecord 10.3847/1538-4357/aaba72 rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved rioxxterms.licenseref.startdate 2018-05-01 dc.contributor.orcid Reynolds, Christopher [0000-0002-1510-4860] dc.identifier.eissn 1538-4357 rioxxterms.type Journal Article/Review pubs.funder-project-id National Aeronautics and Space Administration (NNX17AG27G) pubs.funder-project-id Directorate for Mathematical & Physical Sciences (1333514) cam.issuedOnline 2018-05-04
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