Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745 The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation van Weeren, R. J. et al. “Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745.” The Astrophysical Journal 835.2 (2017): 197. © 2017 The American Astronomical Society As Published http://dx.doi.org/10.3847/1538-4357/835/2/197 Publisher IOP Publishing Version Final published version Citable link http://hdl.handle.net/1721.1/110039 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astrophysical Journal, 835:197 (16pp), 2017 February 1 doi:10.3847/1538-4357/835/2/197 © 2017. The American Astronomical Society. All rights reserved. Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745 R. J. van Weeren1,20, G. A. Ogrean2,21, C. Jones1, W. R. Forman1, F. Andrade-Santos1, Connor J. J. Pearce1,3, A. Bonafede4, M. Brüggen4, E. Bulbul5, T. E. Clarke6, E. Churazov7,8, L. David1, W. A. Dawson9, M. Donahue10, A. Goulding11, R. P. Kraft1, B. Mason12, J. Merten13, T. Mroczkowski14, P. E. J. Nulsen1,15, P. Rosati16, E. Roediger17,22, S. W. Randall1, J. Sayers18, K. Umetsu19, A. Vikhlinin1, and A. Zitrin18,20 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected] 2 Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060, USA 3 Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK 4 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany 5 Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA 6 U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, USA 7 Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching, Germany 8 Space Research Institute, Profsoyuznaya 84/32, Moscow, 117997, Russia 9 Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94550, USA 10 Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA 11 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA 12 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA 13 Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK 14 ESO—European Organization for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München, Germany 15 ICRAR, University of Western Australia, 35 Stirling Hwy, Crawley WA 6009, Australia 16 Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Saragat 1, I-44122 Ferrara, Italy 17 E.A. Milne Centre for Astrophysics, Department of Physics & Mathematics, University of Hull, Cottinton Road, Hull, HU6 7RX, UK 18 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125, USA 19 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan Received 2016 November 15; revised 2016 December 22; accepted 2016 December 24; published 2017 January 31 Abstract To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandraobservations of the HST Frontier Fields cluster MACSJ0717.5+3745. The Chandraimage shows a complex merger event, with at least four components belonging to different merging subclusters. Northwestof the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeastof this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleuslead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re- acceleration (revival) of fossil electrons. The presence of hot 20 keV ICM gas detected by Chandranear the relic location provides additional support for this re-acceleration scenario. Key words: galaxies: clusters: individual (MACS J0717.5+3745) – galaxies: clusters: intracluster medium – radiation mechanisms: non-thermal – X-rays: galaxies: clusters 1. Introduction at least four separate merging substructures. Regions of the intracluster medium (ICM) are heated to 20 keV (Ma Merging galaxy clusters are excellent laboratories to investi- et al. 2008, 2009; Limousin et al. 2012, 2016). A study of the gate cluster formation and to explore how the particles that Sunyaev–Zel’dovich (SZ) effect provided further evidence for produce cluster-scale diffuse radio emission are accelerated. the presence of shock-heated gas (Mroczkowski et al. 2012). A textbook example of an extreme merging cluster is ( ) ( ) + + Mroczkowski et al. 2012 and Sayers et al. 2013 found MACS J0717.5 3745. MACS J0717.5 3745 was discovered evidence for a kinetic SZ signal for one of the subclusters, ( ) − by Edge et al. 2003 as part of the MAssive Cluster Survey confirming the large velocity offset (≈3000 km s 1) found ( ) MACS; Ebeling et al. 2001 and is located at a redshift of earlier from spectroscopy data (Ma et al. 2009). A recent study = z 0.5458. The cluster is very hot, with a global X-ray reported the detection of a second kinetic SZ component temperature of 11.6±0.5 keV (Ebeling et al. 2007). belonging to another subcluster (Adam et al. 2016).Connected MACSJ0717.5+3745 is one of the most complex and to the cluster in the southeast is a ∼4Mpc (projected length) dynamically disturbed clusters known. The cluster consists of galaxy and gas filament (Ebeling et al. 2004;Jauzacetal.2012). Because of the large total mass (Mvir =´()3.5 0.6 20 15 ) Clay Fellow. 10 M; Umetsu et al. 2014 , complex mass distribution, 21 Hubble Fellow. and relatively shallow mass profile (Zitrin et al. 2009), the 22 Visiting Scientist. cluster provides a large area of sky with high lensing 1 The Astrophysical Journal, 835:197 (16pp), 2017 February 1 Weeren et al. magnificationand is thus selected as part of the Cluster 2. Observations and Data Reduction Lensing And Supernova survey with Hubble (CLASH, Post- 2.1. JVLA Observations man et al. 2012; Medezinski et al. 2013) and the HST Frontier Fields program23 (Lotz et al. 2014, 2016) to find high-z lensed JVLA observations of MACSJ07175+3745 were obtained objects. in the L-, S-, and C-bands, covering the frequency range from 1 Ma et al. (2009) reported decrements in the ICM temperature to 6.5 GHz. An overview of the frequency bands and near two of the subclusters of MACSJ0717.5+3745, which observations is given in Table 1. The total recorded bandwidth they interpret as remnants of cool cores. For one of these was 1 GHz for the L-bandand was 2 GHz for the S- and subclusters, Ma et al. (2009) measured a temperature 5.7 keV C-bands. For the primary calibrators we used 3C138 and temperature, suggesting thatthis component is still at the early 3C147. J0713+4349 was included as a secondary calibrator. stage of merging. Diego et al. (2015) found that one of the dark All four polarization products were recorded. matter components (the one furthest to the northwest) has a The data were reduced with CASA (McMullin et al. 2007) significant offset from the closest X-ray peak. Significant version 4.5 and data from the different observing runs were all offsets between the lensing and X-ray peaks are expected in the processed in the same way. The data reduction procedure is ( ) case of a high-speed collision in the plane of the sky. described in more detail in van Weeren et al. 2016b .To Previous radio studies of the cluster have focused on diffuse summarize, the data were calibrated for the antenna position radio emission that is present in the cluster (Bonafede et al. offsets, elevation dependent gains, global delay, cross-hand 2009; van Weeren et al. 2009b; Pandey-Pommier et al. 2013). delay, bandpass, polarization leakage and angles, and temporal The cluster hosts a giant radio halo extending over an area of gain variations using the primary and secondary calibrator fi fl about 1.6 Mpc. Polarized emission from the radio halo was sources. RFI was identi ed and agged with the AOFlagger ( ) detected by Bonafede et al. (2009). The radio luminosity Offringa et al. 2010 . The calibration solutions from the (1.4 GHz radio power) is the largest known for any cluster, in primary and secondary calibrator sources were applied to the ’ target field and several rounds of self-calibration were carried agreement with the cluster s large mass and high global fi temperature (e.g., Cassano et al. 2013). out to re ne the gain solutions. – After the individual data sets were calibrated, the observa- The cluster also hosts a large 0.7 0.8 Mpc radio relic. It has fi ( been suggested that the radio relic in the cluster traces a large- tions from the different con gurations for the same frequency band) were combined and imaged together.