PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics
We report upgraded Giant Metrewave Radio Telescope and Karl J. Jansky Very Large Array radio observations of a low-mass merging galaxy cluster PSZ2 G181.06+48.47. This exceptional galaxy cluster hosts two megaparsec-scale diffuse sources, symmetrically located with respect to the cluster center and...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adbbb9 |
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| author | Kamlesh Rajpurohit Andra Stroe Ewan O’Sullivan Eunmo Ahn Wonki Lee Hyejeon Cho M. James Jee Reinout van Weeren Lorenzo Lovisari Kyle Finner Aurora Simionescu William Forman Timothy Shimwell Christine Jones Zhenlin Zhu Scott Randall |
| author_facet | Kamlesh Rajpurohit Andra Stroe Ewan O’Sullivan Eunmo Ahn Wonki Lee Hyejeon Cho M. James Jee Reinout van Weeren Lorenzo Lovisari Kyle Finner Aurora Simionescu William Forman Timothy Shimwell Christine Jones Zhenlin Zhu Scott Randall |
| author_sort | Kamlesh Rajpurohit |
| collection | DOAJ |
| description | We report upgraded Giant Metrewave Radio Telescope and Karl J. Jansky Very Large Array radio observations of a low-mass merging galaxy cluster PSZ2 G181.06+48.47. This exceptional galaxy cluster hosts two megaparsec-scale diffuse sources, symmetrically located with respect to the cluster center and separated by about 2.6 Mpc in projection. We detect these low surface brightness sources in our new high-frequency observations (0.3–2 GHz) and classify them as radio relics associated with merger-driven shock fronts. The southwest relic exhibits an inverted morphology and shows evidence of spectral steepening in the post-shock region, potentially tracing a high Mach number shock (∼4) under the framework of diffusive shock acceleration. The northeast relic is found to be highly polarized with a 22% average polarization fraction at 1.5 GHz and aligned magnetic field vectors. Its spectral and polarization properties, along with the presence of a nearby tailed galaxy, support reacceleration scenarios. The merger axis defined by the two relics is tilted by ∼45° with respect to the plane of the sky, which implies an unprecedented physical separation of ∼3.5 Mpc. We also detect a possible faint radio halo, suggesting weak turbulence in the central cluster region. We conclude that the faint double relics can be best explained by two outward-moving shock waves in which particles are (re)accelerated and that the cluster is in an evolved merger state. PSZ2 G181.06+48.47 presents a unique opportunity to investigate particle acceleration in low-mass systems characterized by large relic separations. |
| format | Article |
| id | doaj-art-301eeff2ebef40138616314cb678c1c3 |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-301eeff2ebef40138616314cb678c1c32025-08-20T02:12:20ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198412510.3847/1538-4357/adbbb9PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio RelicsKamlesh Rajpurohit0https://orcid.org/0000-0001-7509-2972Andra Stroe1https://orcid.org/0000-0001-8322-4162Ewan O’Sullivan2https://orcid.org/0000-0002-5671-6900Eunmo Ahn3https://orcid.org/0009-0009-4676-7868Wonki Lee4https://orcid.org/0000-0002-1566-5094Hyejeon Cho5https://orcid.org/0000-0001-5966-5072M. James Jee6https://orcid.org/0000-0002-5751-3697Reinout van Weeren7https://orcid.org/0000-0002-0587-1660Lorenzo Lovisari8https://orcid.org/0000-0002-3754-2415Kyle Finner9https://orcid.org/0000-0002-4462-0709Aurora Simionescu10https://orcid.org/0000-0002-9714-3862William Forman11https://orcid.org/0000-0002-9478-1682Timothy Shimwell12https://orcid.org/0000-0001-5648-9069Christine Jones13https://orcid.org/0000-0003-2206-4243Zhenlin Zhu14https://orcid.org/0000-0001-8812-8284Scott Randall15https://orcid.org/0000-0002-3984-4337Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.eduCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.edu; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USACenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.eduDepartment of Astronomy, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of KoreaDepartment of Astronomy, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of KoreaDepartment of Astronomy, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea; Center for Galaxy Evolution Research, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of KoreaDepartment of Astronomy, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea; Department of Physics and Astronomy, University of California , Davis, One Shields Avenue, Davis, CA 95616, USALeiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden, The NetherlandsCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.edu; INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano , via A. Corti 12, 20133 Milano, ItalyIPAC, California Institute of Technology , 1200 E California Blvd., Pasadena, CA 91125, USASRON, Netherlands Institute for Space Research , Sorbonnelaan 2, 3584 CA Utrecht, The NetherlandsCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.eduLeiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden, The Netherlands; ASTRON, the Netherlands Institute for Radio Astronomy , Postbus 2, NL-7990 AA Dwingeloo, The NetherlandsCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.eduCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.edu; SRON Netherlands Institute for Space Research , Niels Bohrweg 4, 2333 CA Leiden, The Netherlands; Leiden Observatory, Leiden University , Niels Bohrweg 2, 2300 RA Leiden, The NetherlandsCenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USA ; kamlesh.rajpurohit@cfa.harvard.eduWe report upgraded Giant Metrewave Radio Telescope and Karl J. Jansky Very Large Array radio observations of a low-mass merging galaxy cluster PSZ2 G181.06+48.47. This exceptional galaxy cluster hosts two megaparsec-scale diffuse sources, symmetrically located with respect to the cluster center and separated by about 2.6 Mpc in projection. We detect these low surface brightness sources in our new high-frequency observations (0.3–2 GHz) and classify them as radio relics associated with merger-driven shock fronts. The southwest relic exhibits an inverted morphology and shows evidence of spectral steepening in the post-shock region, potentially tracing a high Mach number shock (∼4) under the framework of diffusive shock acceleration. The northeast relic is found to be highly polarized with a 22% average polarization fraction at 1.5 GHz and aligned magnetic field vectors. Its spectral and polarization properties, along with the presence of a nearby tailed galaxy, support reacceleration scenarios. The merger axis defined by the two relics is tilted by ∼45° with respect to the plane of the sky, which implies an unprecedented physical separation of ∼3.5 Mpc. We also detect a possible faint radio halo, suggesting weak turbulence in the central cluster region. We conclude that the faint double relics can be best explained by two outward-moving shock waves in which particles are (re)accelerated and that the cluster is in an evolved merger state. PSZ2 G181.06+48.47 presents a unique opportunity to investigate particle acceleration in low-mass systems characterized by large relic separations.https://doi.org/10.3847/1538-4357/adbbb9Non-thermal radiation sourcesRadio continuum emissionGalaxy clustersLarge-scale structure of the universeExtragalactic radio sources |
| spellingShingle | Kamlesh Rajpurohit Andra Stroe Ewan O’Sullivan Eunmo Ahn Wonki Lee Hyejeon Cho M. James Jee Reinout van Weeren Lorenzo Lovisari Kyle Finner Aurora Simionescu William Forman Timothy Shimwell Christine Jones Zhenlin Zhu Scott Randall PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics The Astrophysical Journal Non-thermal radiation sources Radio continuum emission Galaxy clusters Large-scale structure of the universe Extragalactic radio sources |
| title | PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics |
| title_full | PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics |
| title_fullStr | PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics |
| title_full_unstemmed | PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics |
| title_short | PSZ2 G181.06+48.47. II. Radio Analysis of a Low-mass Cluster with Exceptionally Distant Radio Relics |
| title_sort | psz2 g181 06 48 47 ii radio analysis of a low mass cluster with exceptionally distant radio relics |
| topic | Non-thermal radiation sources Radio continuum emission Galaxy clusters Large-scale structure of the universe Extragalactic radio sources |
| url | https://doi.org/10.3847/1538-4357/adbbb9 |
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