Abell 746: A Highly Disturbed Cluster Undergoing Multiple Mergers

The Astrophysical Journal, vol. 966, pp. 38

Abstract

Abstract We present deep XMM-Newton, Karl G. Jansky Very Large Array, and upgraded Giant Metrewave Radio Telescope observations of Abell 746, a cluster that hosts a plethora of diffuse emission sources that provide evidence for the acceleration of relativistic particles. Our new XMM-Newton images reveal a complex morphology of the thermal gas with several substructures. We observe an asymmetric temperature distribution across the cluster: the southern regions exhibit higher temperatures, reaching ∼9 keV, while the northern regions have lower temperatures (≤4 keV), likely due to a complex merger. We find evidence of three surface brightness edges and one candidate edge, of which three are merger-driven shock fronts. Combining our new data with published LOw-Frequency ARray observations has unveiled the nature of diffuse sources in this system. The bright NW relic shows thin filaments and a high degree of polarization with aligned magnetic field vectors. We detect a density jump, aligned with the fainter relic to the north. To the south, we detect high-temperature regions, consistent with the shock-heated regions and a density jump coincident with the northern tip of the southern radio structure. Its integrated spectrum shows a high-frequency steepening. Lastly, we find that the cluster hosts large-scale radio halo emission. A comparison of the thermal and nonthermal emission reveals an anticorrelation between the bright radio and X-ray features at the center. Our findings suggest that Abell 746 is a complex system that involves multiple mergers.

Authors 24

1. K. Rajpurohit corresponding

   Istituto di Radioastronomia di Bologna · Center for Astrophysics Harvard & Smithsonian · National Institute for Astrophysics · University of Bologna

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

   DIFA—Universitá di Bologna, via Gobetti 93/2, 40129 Bologna, Italy

   INAF-IRA, via Gobetti 101, 40129 Bologna, Italy

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

2. L. Lovisari

   Center for Astrophysics Harvard & Smithsonian · National Institute for Astrophysics

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

   INAF-IASF Milano, via A. Corti 12, 20133 Milano, Italy

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

3. A. Botteon

   Istituto di Radioastronomia di Bologna · National Institute for Astrophysics

   Affiliation as printed

   INAF-IRA, via Gobetti 101, 40129 Bologna, Italy

4. Christine J. Jones

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

5. W. Forman

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

6. Ewan O’Sullivan

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

7. Reinout J. van Weeren Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands

8. Kim HyeongHan

   Yonsei University

   Affiliation as printed

   Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea

9. A. Bonafede

   Istituto di Radioastronomia di Bologna · National Institute for Astrophysics · University of Bologna

   Affiliation as printed

   DIFA—Universitá di Bologna, via Gobetti 93/2, 40129 Bologna, Italy

   INAF-IRA, via Gobetti 101, 40129 Bologna, Italy

10. M. James Jee

    Yonsei University

    Affiliation as printed

    Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea

11. F. Vazza

    Istituto di Radioastronomia di Bologna · National Institute for Astrophysics · University of Bologna

    Affiliation as printed

    DIFA—Universitá di Bologna, via Gobetti 93/2, 40129 Bologna, Italy

    INAF-IRA, via Gobetti 101, 40129 Bologna, Italy

12. G. Brunetti

    Istituto di Radioastronomia di Bologna · National Institute for Astrophysics

    Affiliation as printed

    INAF-IRA, via Gobetti 101, 40129 Bologna, Italy

13. Hyejeon Cho corresponding

    Yonsei University

    Affiliation as printed

    Center for Galaxy Evolution Research, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea

    Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea

14. Paola Domínguez-Fernández

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

15. Andra Stroe

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

16. Kyle Finner

    California Institute of Technology · Infrared Processing and Analysis Center

    Affiliation as printed

    IPAC, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA

17. M. Brüggen

    Universität Hamburg

    Affiliation as printed

    Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

18. Jan M. Vrtilek

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

19. L. P. David

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

20. Gerrit Schellenberger

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

21. David Wittman

    University of California, Davis

    Affiliation as printed

    Department of Physics and Astronomy, University of California, Davis, CA 95616 USA

22. G. Lusetti

    Universität Hamburg

    Affiliation as printed

    Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

23. Ralph Kraft

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; kamlesh.rajpurohit@cfa.harvard.edu

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

24. F. de Gasperin

    Universität Hamburg · Istituto di Radioastronomia di Bologna · National Institute for Astrophysics

    Affiliation as printed

    Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

    INAF-IRA, via Gobetti 101, 40129 Bologna, Italy