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Title: Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Abstract

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of 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-northeast of 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 100–300 kpc. 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 nucleus lead into the large radio relic where the radio spectrum flattens again.more » 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 Chandra near the relic location provides additional support for this re-acceleration scenario.« less

Authors:
; ; ; ; ; ; ;  [1];  [2]; ;  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12] more »; « less
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)
  3. Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany)
  4. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
  5. U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375 (United States)
  6. Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany)
  7. Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94550 (United States)
  8. Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
  9. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  10. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
  11. Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
  12. ESO—European Organization for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München (Germany)
Publication Date:
OSTI Identifier:
22663917
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; DENSITY; ELECTRONS; GALAXY CLUSTERS; GALAXY NUCLEI; KEV RANGE; RADIO GALAXIES; SPECTRA; X RADIATION; X-RAY GALAXIES

Citation Formats

Van Weeren, R. J., Jones, C., Forman, W. R., Andrade-Santos, F., Pearce, Connor J. J., David, L., Kraft, R. P., Nulsen, P. E. J., Ogrean, G. A., Bonafede, A., Brüggen, M., Bulbul, E., Clarke, T. E., Churazov, E., Dawson, W. A., Donahue, M., Goulding, A., Mason, B., Merten, J., Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu, and and others. Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/197.
Van Weeren, R. J., Jones, C., Forman, W. R., Andrade-Santos, F., Pearce, Connor J. J., David, L., Kraft, R. P., Nulsen, P. E. J., Ogrean, G. A., Bonafede, A., Brüggen, M., Bulbul, E., Clarke, T. E., Churazov, E., Dawson, W. A., Donahue, M., Goulding, A., Mason, B., Merten, J., Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu, & and others. Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745. United States. doi:10.3847/1538-4357/835/2/197.
Van Weeren, R. J., Jones, C., Forman, W. R., Andrade-Santos, F., Pearce, Connor J. J., David, L., Kraft, R. P., Nulsen, P. E. J., Ogrean, G. A., Bonafede, A., Brüggen, M., Bulbul, E., Clarke, T. E., Churazov, E., Dawson, W. A., Donahue, M., Goulding, A., Mason, B., Merten, J., Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu, and and others. Wed . "Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745". United States. doi:10.3847/1538-4357/835/2/197.
@article{osti_22663917,
title = {Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745},
author = {Van Weeren, R. J. and Jones, C. and Forman, W. R. and Andrade-Santos, F. and Pearce, Connor J. J. and David, L. and Kraft, R. P. and Nulsen, P. E. J. and Ogrean, G. A. and Bonafede, A. and Brüggen, M. and Bulbul, E. and Clarke, T. E. and Churazov, E. and Dawson, W. A. and Donahue, M. and Goulding, A. and Mason, B. and Merten, J. and Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu and and others},
abstractNote = {To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of 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-northeast of 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 100–300 kpc. 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 nucleus lead 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 Chandra near the relic location provides additional support for this re-acceleration scenario.},
doi = {10.3847/1538-4357/835/2/197},
journal = {Astrophysical Journal},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of 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. Here, we detect a density discontinuity north-northeast of this core, which we speculatemore » 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 100–300 kpc. 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 nucleus lead 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 Chandra near the relic location provides additional support for this re-acceleration scenario.« less
  • We report on high-resolution JVLA and Chandra observations of the Hubble Space Telescope (HST) Frontier Cluster MACS J0717.5+3745. MACS J0717.5+3745 offers the largest contiguous magnified area of any known cluster, making it a promising target to search for lensed radio and X-ray sources. With the high-resolution 1.0–6.5 GHz JVLA imaging in A and B configuration, we detect a total of 51 compact radio sources within the area covered by the HST imaging. Within this sample, we find seven lensed sources with amplification factors larger than two. None of these sources are identified as multiply lensed. Based on the radio luminosities,more » the majority of these sources are likely star-forming galaxies with star-formation rates (SFRs) of 10–50 M yr -1 located at 1≲ z ≲ 2. Two of the lensed radio sources are also detected in the Chandra image of the cluster. These two sources are likely active galactic nuclei, given their 2–10 keV X-ray luminosities of ~ 10 43-44 erg s -1. From the derived radio luminosity function, we find evidence for an increase in the number density of radio sources at 0.6 < z < 2.0, compared to a z < 0.3 sample. Lastly, our observations indicate that deep radio imaging of lensing clusters can be used to study star-forming galaxies, with SFRs as low as ~10M yr -1, at the peak of cosmic star formation history.« less
  • Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold fronts, X-ray substructure, radio halos, and offsets between the dark matter (DM) and the gas components. Using observations from Chandra, the Jansky Very Large Array, the Giant Metrewave Radio Telescope, and the Hubble Space Telescope, we present a multiwavelength analysis of the merging Frontier Fields cluster MACS J0416.1-2403 (z = 0.396), which consists of NE and SW subclusters whose cores are separated on the sky by ∼250 kpc. We find that the NE subcluster has a compact core and hosts an X-ray cavity,more » yet it is not a cool core. Approximately 450 kpc south–southwest of the SW subcluster, we detect a density discontinuity that corresponds to a compression factor of ∼1.5. The discontinuity was most likely caused by the interaction of the SW subcluster with a less massive structure detected in the lensing maps SW of the subcluster's center. For both the NE and the SW subclusters, the DM and the gas components are well-aligned, suggesting that MACS J0416.1-2403 is a pre-merging system. The cluster also hosts a radio halo, which is unusual for a pre-merging system. The halo has a 1.4 GHz power of (1.3 ± 0.3) × 10{sup 24} W Hz{sup −1}, which is somewhat lower than expected based on the X-ray luminosity of the cluster if the spectrum of the halo is not ultra-steep. We suggest that we are either witnessing the birth of a radio halo, or have discovered a rare ultra-steep spectrum halo.« less
  • We present 90, 140, and 268 GHz subarcminute resolution imaging of the Sunyaev-Zel'dovich effect (SZE) in the disturbed, intermediate-redshift (z 0.5458) galaxy cluster MACS J0717.5+3745, a triple-merger system comprising four distinct, optically detected subclusters. Our 90 GHz SZE data result in a sensitive, 34 {mu}Jy beam{sup -1} map of the SZE at 13'' effective resolution using the MUSTANG bolometer array on the Green Bank Telescope (GBT). Our 140 and 268 GHz SZE imaging, with resolutions of 58'' and 31'' and sensitivities of 1.8 and 3.3 mJy beam{sup -1}, respectively, was obtained through observations from the Caltech Submillimeter Observatory using Bolocam.more » We compare these maps to a two-dimensional pressure map derived from Chandra X-ray observations. Our MUSTANG SZE data confirm previous indications from Chandra of a pressure enhancement due to shock-heated, {approx}> 20 keV gas immediately adjacent to extended radio emission seen in low-frequency radio maps of this cluster. MUSTANG also detects pressure substructure that is not well constrained by the Chandra X-ray data in the remnant core of a merging subcluster. We find that the small-scale pressure enhancements in the MUSTANG data amount to {approx}2% of the total pressure measured in the 140 GHz Bolocam observations. The X-ray inferred pseudo-pressure template also fails on larger scales to accurately describe the Bolocam data, particularly at the location of the subcluster with a remnant core known to have a high line-of-sight optical velocity of {approx}3200 km s{sup -1}. Our Bolocam data are adequately described when we add an additional component-not described by a thermal SZE spectrum-to the X-ray template coincident with this subcluster. Using flux densities extracted from our model fits, and marginalizing over the X-ray spectroscopic temperature constraints for the region, we fit a thermal + kinetic SZE spectrum to our Bolocam data and find that the subcluster has a best-fit line-of-sight proper velocity v{sub z} 3600{sup +3440}{sub -{sub 2160}} km s{sup -1}, in agreement with the optical velocity estimates for the subcluster. The probability v{sub z} {<=} 0 given our measurements is 2.1%. Repeating this analysis using flux densities measured directly from our maps results in a 3.4% probability v{sub z} {<=} 0. We note that this tantalizing result for the kinetic SZE is on resolved, subcluster scales.« less
  • The Grism Lens-Amplified Survey from Space (GLASS) is a Hubble Space Telescope (HST) Large Program, which will obtain 140 orbits of grism spectroscopy of the core and infall regions of 10 galaxy clusters, selected to be among the very best cosmic telescopes. Extensive HST imaging is available from many sources including the CLASH and Frontier Fields programs. We introduce the survey by analyzing spectra of faint multiply-imaged galaxies and z ≳ 6 galaxy candidates obtained from the first 7 orbits out of 14 targeting the core of the Frontier Fields cluster MACSJ0717.5+3745. Using the G102 and G141 grisms to covermore » the wavelength range 0.8-1.7 μm, we confirm four strongly lensed systems by detecting emission lines in each of the images. For the 9 z ≳ 6 galaxy candidates clear from contamination, we do not detect any emission lines down to a 7 orbit 1σ noise level of ∼5 × 10{sup –18} erg s{sup –1} cm{sup –2}. Taking lensing magnification into account, our flux sensitivity reaches ∼0.2-5 × 10{sup –18} erg s{sup –1}cm{sup –2}. These limits over an uninterrupted wavelength range rule out the possibility that the high-z galaxy candidates are instead strong line emitters at lower redshift. These results show that by means of careful modeling of the background—and with the assistance of lensing magnification—interesting flux limits can be reached for large numbers of objects, avoiding pre-selection and the wavelength restrictions inherent to ground-based multi-slit spectroscopy. These observations confirm the power of slitless HST spectroscopy even in fields as crowded as a cluster core.« less