Publication Search Results

ID: 159641
Type: article
Authors: Jimenez-Gallardo, A.; Massaro, F.; Paggi, A.; D'Abrusco, Raffaele; Prieto, M. A.; Peña-Herazo, H. A.; Berta, V.; Ricci, F.; Stuardi, C.; Wilkes, Belinda J.; O'Dea, C. P.; Baum, S. A.; Kraft, Ralph P.; Forman, William R.; Jones-Forman, Christine; Mingo, B.; Liuzzo, E.; Balmaverde, B.; Capetti, A.; Missaglia, V.; Hardcastle, M. J.; Baldi, R. D.; Morabito, L. K.
Abstract: We present a systematic analysis of the extended X-ray emission discovered around 35 FR II radio galaxies from the revised Third Cambridge Catalog (3CR) Chandra Snapshot Survey with redshifts between 0.05 and 0.9. We aimed to (i) test for the presence of extended X-ray emission around FR II radio galaxies, (ii) investigate whether the extended emission origin is due to inverse Compton (IC) scattering of seed photons arising from the cosmic microwave background (CMB) or thermal emission from an intracluster medium (ICM), and (iii) test the impact of this extended emission on hot-spot detection. We investigated the nature of the extended X-ray emission by studying its morphology and compared our results with low-frequency radio observations (i.e., ∼150 MHz) in the TGSS and LOFAR archives, as well as with optical images from Pan-STARRS. In addition, we optimized a search for X-ray counterparts of hot spots in 3CR FR II radio galaxies. We found statistically significant extended emission (>3σ confidence level) along the radio axis of ∼90% and in the perpendicular direction of ∼60% of the galaxies in our sample. We confirmed the detection of seven hot spots in the 0.5-3 keV energy range. In the cases where the emission in the direction perpendicular to the radio axis is comparable to that along the radio axis, we suggest that the underlying radiative process is thermal emission from the ICM. Otherwise, the dominant radiative process is likely nonthermal IC/CMB emission from lobes. We found that nonthermal IC/CMB is the dominant process in ∼70% of the sources in our sample, while thermal emission from the ICM dominates in ∼15% of them.

ID: 157836
Type: article
Authors: Acebron, Ana; Zitrin, Adi; Coe, Dan; Mahler, Guillaume; Sharon, Keren; Oguri, Masamune; Bradač, Maruša; Bradley, Larry D.; Frye, Brenda; Forman, Christine J.; Strait, Victoria; Su, Yuanyuan; Umetsu, Keiichi; Andrade-Santos, Felipe; Avila, Roberto J.; Carrasco, Daniela; Cerny, Catherine; Czakon, Nicole G.; Dawson, William A.; Fox, Carter; Hoag, Austin T.; Huang, Kuang-Han; Johnson, Traci L.; Kikuchihara, Shotaro; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Nonino, Mario; Oesch, Pascal A.; Ogaz, Sara; Ouchi, Masami; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Ryan, Russell E.; Salmon, Brett; Stark, Daniel P.; Toft, Sune; Trenti, Michele; Vulcani, Benedetta; Welch, Brian
Abstract: Extensive surveys with the Hubble Space Telescope over the past decade, targeting some of the most massive clusters in the sky, have uncovered dozens of galaxy cluster strong lenses. The massive cluster strong-lens scale is typically θ_E ∼ 10″ to ∼30″-35″, with only a handful of clusters known with Einstein radii θ_E ∼ 40″ or above (for z_source = 2, nominally). Here we report another very large cluster lens, RXC J0032.1+1808 (z = 0.3956), the second-richest cluster in the redMapper cluster catalog and the 85th most massive cluster in the Planck Sunyaev-Zel'dovich catalog. With our light-traces-mass and fully parametric approaches, we construct strong-lensing models based on 18 multiple images of five background galaxies newly identified in the Hubble data, mainly from the Reionization Lensing Cluster Survey (RELICS), in addition to a known sextuply imaged system in this cluster. Furthermore, we compare these models to Lenstool and GLAFIC models that were produced independently as part of the RELICS program. All models reveal a large effective Einstein radius of θ_E ≃ 40″ (z_source = 2), owing to the obvious concentration of substructures near the cluster center. Although RXC J0032.1+1808 has a very large critical area and high lensing strength, only three magnified high-redshift candidates are found within the field targeted by RELICS. Nevertheless, we expect many more high-redshift candidates will be seen in wider and deeper observations with Hubble or the James Webb Space Telescope. Finally, the comparison between several algorithms demonstrates that the total error budget is largely dominated by systematic uncertainties.

ID: 156376
Type: article
Authors: Liu, Wenhao; Sun, Ming; Nulsen, Paul E. J.; Worrall, Diana M.; Birkinshaw, Mark; Sarazin, Craig; Forman, William R.; Jones, Christine; Ge, Chong
Abstract: We present results from a deep (174 ks) Chandra observation of the FR-II radio galaxy 3C 220.1, the central brightest cluster galaxy (BCG) of a kT ∼ 4 keV cluster at z = 0.61. The temperature of the hot cluster medium drops from ∼5.9 to ∼3.9 keV at ∼35 kpc radius, while the temperature at smaller radii may be substantially lower. The central active galactic nucleus (AGN) outshines the whole cluster in X-rays, with a bolometric luminosity of 2.0 × 10⁴⁶ erg s^-1 (∼10 per cent of the Eddington rate). The system shows a pair of potential X-ray cavities ∼35 kpc east and west of the nucleus. The cavity power is estimated within the range of 1.0 × 10⁴⁴ and 1.7 × 10⁴⁵ erg s^-1, from different methods. The X-ray enhancements in the radio lobes could be due to inverse Compton emission, with a total 2-10 keV luminosity of ∼8.0 × 10⁴² erg s^-1. We compare 3C 220.1 with other cluster BCGs, including Cygnus A, as there are few BCGs in rich clusters hosting an FR-II galaxy. We also summarize the jet power of FR-II galaxies from different methods. The comparison suggests that the cavity power of FR-II galaxies likely underestimates the jet power. The properties of 3C 220.1 suggest that it is at the transition stage from quasar-mode feedback to radio- mode feedback.

ID: 157289
Type: article
Authors: Lovisari, Lorenzo; Schellenberger, Gerrit; Sereno, Mauro; Ettori, Stefano; Pratt, Gabriel W.; Forman, William R.; Jones, Christine; Andrade-Santos, Felipe; Randall, Scott; Kraft, Ralph
Abstract: We report the scaling relations derived by fitting the X-ray parameters determined from analyzing the XMM-Newton observations of 120 galaxy clusters in the Planck Early Sunyaev-Zel'dovich (SZ) sample spanning the redshift range of 0.059 _tot and L-T relations determined for different samples. M_tot-T, M_tot-Y_X, and M_tot-M_gas relations show little dependence on the dynamical state of the clusters, but the normalizations of these relations may depend on the mass range investigated. Although most of the clusters investigated in this work reside at relatively low redshift, the fits prefer values of γ, the parameter accounting for the redshift evolution, different from the self-similar predictions. This suggests an evolution ( relations show little dependence on the dynamical state of the clusters, but the normalizations of these relations may depend on the mass range investigated. Although most of the clusters investigated in this work reside at relatively low redshift, the fits prefer values of γ, the parameter accounting for the redshift evolution, different from the self-similar predictions. This suggests an evolution (_tot-T relation) of the scaling relations. For the first time, we find significant evolution (>3σ) of the M_tot-T relation, pointing to an increase of the kinetic- to-thermal energy ratio with redshift. This is consistent with a scenario in which higher-redshift clusters are on average more disturbed than their lower-redshift counterparts.

ID: 158593
Type: article
Authors: Masini, Alberto; Hickox, Ryan C.; Carroll, Christopher M.; Aird, James; Alexander, David M.; Assef, Roberto J.; Bower, Richard; Brodwin, Mark; Brown, Michael J. I.; Chatterjee, Suchetana; Chen, Chien-Ting J.; Dey, Arjun; DiPompeo, Michael A.; Duncan, Kenneth J.; Eisenhardt, Peter R. M.; Forman, William R.; Gonzalez, Anthony H.; Goulding, Andrew D.; Hainline, Kevin N.; Jannuzi, Buell T.; Jones, Christine; Kochanek, Christopher S.; Kraft, Ralph; Lee, Kyoung-Soo; Miller, Eric D.; Mullaney, James; Myers, Adam D.; Ptak, Andrew; Stanford, Adam; Stern, Daniel; Vikhlinin, Alexey; Wake, David A.; Murray, Stephen S.
Abstract: We present a new, ambitious survey performed with the Chandra X-ray Observatory of the 9.3 deg² Boötes field of the NOAO Deep Wide-Field Survey. The wide field probes a statistically representative volume of the universe at high redshift. The Chandra Deep Wide-field Survey exploits the excellent sensitivity and angular resolution of Chandra over a wide area, combining 281 observations spanning 15 yr, for a total exposure time of 3.4 Ms, and detects 6891 X-ray point sources down to limiting fluxes of 4.7 × 10^-16, 1.5 × 10^-16, and 9 ×10^-16 erg cm^-2 s^-1 in the 0.5-7, 0.5-2, and 2-7 keV bands, respectively. The robustness and reliability of the detection strategy are validated through extensive, state-of-the-art simulations of the whole field. Accurate number counts, in good agreement with previous X-ray surveys, are derived thanks to the uniquely large number of point sources detected, which resolve 65.0% ± 12.8% of the cosmic X-ray background between 0.5 and 2 keV and 81.0% ± 11.5% between 2 and 7 keV. Exploiting the wealth of multiwavelength data available on the field, we assign redshifts to ˜94% of the X-ray sources, estimate their obscuration, and derive absorption-corrected luminosities. We provide an electronic catalog containing all of the relevant quantities needed for future investigations.

ID: 157301
Type: article
Authors: Oppenheimer, Benjamin D.; Bogdán, Ákos; Crain, Robert A.; ZuHone, John A.; Forman, William R.; Schaye, Joop; Wijers, Nastasha A.; Davies, Jonathan J.; Jones, Christine; Kraft, Ralph P.; Ghirardini, Vittorio
Abstract: We simulate stacked observations of nearby hot X-ray coronae associated with galaxies in the EAGLE and Illustris-TNG hydrodynamic simulations. A forward modeling pipeline is developed to predict 4 yr eROSITA observations and stacked image analysis, including the effects of instrumental and astrophysical backgrounds. We propose an experiment to stack z ≍ 0.01 galaxies separated by specific star formation rate (sSFR) to examine how the hot (T ≥ 10⁶ K) circumgalactic medium (CGM) differs for high- and low-sSFR galaxies. The simulations indicate that the hot CGM of low-mass ( ${M}_{* }\approx {10}^{10.5}\ {M}_{\odot }$ ), high-sSFR (defined as the top one-third ranked by sSFR) central galaxies will be detectable to a galactocentric radius r ≍ 30-50 kpc. Both simulations predict lower luminosities at fixed stellar mass for the low-sSFR galaxies (the lower third of sSFR) with Illustris-TNG predicting 3× brighter coronae around high-sSFR galaxies than EAGLE. Both simulations predict detectable emission out to r ≍ 150-200 kpc for stacks centered on high-mass ( ${M}_{* }\approx {10}^{11.0}\ {M}_{\odot }$ ) galaxies, with EAGLE predicting brighter X-ray halos. The extended soft X-ray luminosity correlates strongly and positively with the mass of circumgalactic gas within the virial radius (f_CGM). Prior analyses of both simulations have established that f_CGM is reduced by expulsive feedback driven mainly by black hole growth, which quenches galaxy growth by inhibiting replenishment of the interstellar medium. Both simulations predict that eROSITA stacks should not only conclusively detect and resolve the hot CGM around L* galaxies for the first time, but provide a powerful probe of how the baryon cycle operates, for which there remains an absence of consensus between state- of-the-art simulations.

ID: 156218
Type: article
Authors: Salmon, Brett; Coe, Dan; Bradley, Larry; Bouwens, Rychard; Bradač, Marusa; Huang, Kuang-Han; Oesch, Pascal A.; Stark, Daniel; Sharon, Keren; Trenti, Michele; Avila, Roberto J.; Ogaz, Sara; Andrade-Santos, Felipe; Carrasco, Daniela; Cerny, Catherine; Dawson, William; Frye, Brenda L.; Hoag, Austin; Johnson, Traci Lin; Jones, Christine; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Past, Matt; Paterno-Mahler, Rachel; Peterson, Avery; Riess, Adam G.; Rodney, Steven A.; Ryan, Russel E.; Sendra-Server, Irene; Strait, Victoria; Strolger, Louis-Gregory; Umetsu, Keiichi; Vulcani, Benedetta; Zitrin, Adi
Abstract: Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the $z\sim 6\mbox{--}8$ candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of ≈200 arcmin². These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z ∼ 6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z ∼ 6 candidates are as bright as AB mag ∼23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope.

ID: 156917
Type: article
Authors: Schellenberger, Gerrit; David, Laurence P.; Vrtilek, Jan; O'Sullivan, Ewan; Lim, Jeremy; Forman, William; Sun, Ming; Combes, Francoise; Salome, Philippe; Jones, Christine; Giacintucci, Simona; Edge, Alastair; Gastaldello, Fabio; Temi, Pasquale; Brighenti, Fabrizio; Bardelli, Sandro
Abstract: The fate of cooling gas in the centers of galaxy clusters and groups is still not well understood, as is also the case for the complex processes of triggering star formation in central dominant galaxies, reheating of cooled gas by active galactic nuclei (AGN), and the triggering or "feeding" of supermassive black hole outbursts. We present CO observations of the early-type galaxy NGC 5044, which resides at the center of an X-ray bright group with a moderate cooling flow. For our analysis we combine CO(2-1) data from the 7 m antennae of the Atacama Compact Array (ACA) and the ACA total power array (TP). We demonstrate, using the 7 m array data, that we can recover the total flux inferred from IRAM 30 m single-dish observations, which corresponds to a total molecular mass of about 4 × 10⁷M_☉. Most of the recovered flux is blueshifted with respect to the galaxy rest frame and is extended on kiloparsec-scales, suggesting low filling factor dispersed clouds. We find eight concentrations of molecular gas out to a radius of 10″ (1.5 kpc), which we identify with giant molecular clouds. The total molecular gas mass is more centrally concentrated than the X-ray emitting gas, but is extended in the northeast-southwest direction beyond the IRAM 30 m beam. We also compare the spatial extent of the molecular gas to the Hα emission: The CO emission coincides with the very bright Hα region in the center. We do not detect CO emission in the fainter Hα regions. Furthermore, we find two CO absorption features spatially located at the center of the galaxy, within 5 pc projected distance of the AGN, infalling at 255 and 265 km s^-1 relative to the AGN. This indicates that the two giant molecular clouds seen in absorption are most likely within the sphere of influence of the supermassive black hole.

ID: 155247
Type: article
Authors: Acebron, Ana; Alon, May; Zitrin, Adi; Mahler, Guillaume; Coe, Dan; Sharon, Keren; Cibirka, Nathália; Bradač, Maruša; Trenti, Michele; Umetsu, Keiichi; Andrade-Santos, Felipe; Avila, Roberto J.; Bradley, Larry; Carrasco, Daniela; Cerny, Catherine; Czakon, Nicole G.; Dawson, William A.; Frye, Brenda; Hoag, Austin T.; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Kikuchihara, Shotaro; Lam, Daniel; Livermore, Rachael C.; Lovisari, Lorenzo; Mainali, Ramesh; Oesch, Pascal A.; Ogaz, Sara; Ouchi, Masami; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Ryan, Russell E.; Salmon, Brett; Sendra-Server, Irene; Stark, Daniel P.; Strait, Victoria; Toft, Sune; Vulcani, Benedetta
Abstract: Strong gravitational lensing (SL) is a powerful means of mapping the distribution of dark matter. In this work, we perform an SL analysis of the prominent X-ray cluster RXJ0152.7-1357 (z = 0.83, also known as CL0152.7-1357) in Hubble Space Telescope images, taken in the framework of the Reionization Lensing Cluster Survey (RELICS). On top of a previously known z = 3.93 galaxy multiply imaged by RXJ0152.7-1357, for which we identify an additional multiple image, guided by a light- traces-mass approach, we identify seven new sets of multiply imaged background sources lensed by this cluster, spanning the redshift range [1.79-3.93]. A total of 25 multiple images are seen over a small area of ∼0.4 arcmin², allowing us to put relatively high-resolution constraints on the inner matter distribution. Although modestly massive, the high degree of substructure, together with its very elongated shape, makes RXJ0152.7-1357 a very efficient lens for its size. This cluster also comprises the third-largest sample of z ∼ 6-7 candidates in the RELICS survey. Finally, we present a comparison of our resulting mass distribution and magnification estimates with those from a Lenstool model. These models are made publicly available through the Mikulski Archive for Space Telescopes.

ID: 154553
Type: article
Authors: Andrade-Santos, Felipe; van Weeren, Reinout J.; Di Gennaro, Gabriella; Wittman, David; Ryu, Dongsu; Vir Lal, Dharam; Placco, Vinicius M.; Fogarty, Kevin; Jee, M. James; Stroe, Andra; Sobral, David; Forman, William R.; Jones, Christine; Kraft, Ralph P.; Murray, Stephen S.; Brüggen, Marcus; Kang, Hyesung; Santucci, Rafael; Golovich, Nathan; Dawson, William
Abstract: We present deep Chandra observations of A3411─12, a remarkable merging cluster that hosts the most compelling evidence for electron reacceleration at cluster shocks to date. Using the {Y}_{{X}}{--}M scaling relation, we find r ₅₀₀ ∼ 1.3 Mpc, {M}₅₀₀=(7.1+/- 0.7)× {10}¹⁴ {M}_ȯ , {kT}=6.5+/- 0.1 {keV}, and a gas mass of {M}_{{g},500}=(9.7+/- 0.1)× {10}¹³{M}_ȯ . The gas mass fraction within r ₅₀₀ is {f}_{{g}}=0.14+/- 0.01. We compute the shock strength using density jumps to conclude that the Mach number of the merging subcluster is small (M≤slant {1.15}_-0.09^+0.14). We also present density, temperature, pseudo-pressure, and pseudo-entropy maps. Based on the pseudo-entropy map, we conclude that the cluster is undergoing a mild merger, consistent with the small Mach number. On the other hand, radio relics extend over Mpc scale in the A3411─12 system, which strongly suggests that a population of energetic electrons already existed over extended regions of the cluster.

ID: 155151
Type: article
Authors: Bocquet, S.; Dietrich, J. P.; Schrabback, T.; Bleem, L. E.; Klein, M.; Allen, S. W.; Applegate, D. E.; Ashby, Matthew L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Brodwin, M.; Bulbul, Esra; Canning, R. E. A.; Capasso, R.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H. -M; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, William R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Grandis, S.; Gupta, N.; Halverson, N. W.; Hlavacek-Larrondo, J.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Huang, N.; Jones, Christine; Khullar, G.; Knox, L.; Kraft, Ralph; Lee, A. T.; von der Linden, A.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Morris, R. G.; Padin, S.; Patil, S.; Pryke, C.; Rapetti, D.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Stalder, Brian; Stanford, S. A.; Staniszewski, Z.; Stark, Antony A.; Story, K. T.; Strazzullo, V.; Stubbs, Christopher W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, Alexey; Williamson, R.; Zenteno, A.
Abstract: We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg² SPT-SZ survey. The sample spans the redshift range 0.25 SPT-SZ survey. The sample spans the redshift range 0.25 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 _m = 0.276 ± 0.047, σ ₈ = 0.781 ± 0.037, and σ ₈(Ω_m/0.3)^0.2 = 0.766 ±0.025. The redshift evolutions of the X-ray Y _X-mass and M _gas-mass relations are both consistent with self-similar evolution to within 1σ. The mass slope of the Y _X-mass relation shows a 2.3σ deviation from self-similarity. Similarly, the mass slope of the M _gas-mass relation is steeper than self- similarity at the 2.5σ level. In a νwCDM cosmology, we measure the dark energy equation-of-state parameter w = -1.55 ± 0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z ∼ 1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.

ID: 154720
Type: article
Authors: Coe, Dan; Salmon, Brett; Bradač, Maruša; Bradley, Larry D.; Sharon, Keren; Zitrin, Adi; Acebron, Ana; Cerny, Catherine; Cibirka, Nathália; Strait, Victoria; Paterno-Mahler, Rachel; Mahler, Guillaume; Avila, Roberto J.; Ogaz, Sara; Huang, Kuang-Han; Pelliccia, Debora; Stark, Daniel P.; Mainali, Ramesh; Oesch, Pascal A.; Trenti, Michele; Carrasco, Daniela; Dawson, William A.; Rodney, Steven A.; Strolger, Louis-Gregory; Riess, Adam G.; Jones, Christine; Frye, Brenda L.; Czakon, Nicole G.; Umetsu, Keiichi; Vulcani, Benedetta; Graur, Or; Jha, Saurabh W.; Graham, Melissa L.; Molino, Alberto; Nonino, Mario; Hjorth, Jens; Selsing, Jonatan; Christensen, Lise; Kikuchihara, Shotaro; Ouchi, Masami; Oguri, Masamune; Welch, Brian; Lemaux, Brian C.; Andrade-Santos, Felipe; Hoag, Austin T.; Johnson, Traci L.; Peterson, Avery; Past, Matthew; Fox, Carter; Agulli, Irene; Livermore, Rachael; Ryan, Russell E.; Lam, Daniel; Sendra-Server, Irene; Toft, Sune; Lovisari, Lorenzo; Su, Yuanyuan
Abstract: Large surveys of galaxy clusters with the Hubble Space Telescope (HST) and Spitzer, including the Cluster Lensing And Supernova survey with Hubble and the Frontier Fields, have demonstrated the power of strong gravitational lensing to efficiently deliver large samples of high- redshift galaxies. We extend this strategy through a wider, shallower survey named RELICS, the Reionization Lensing Cluster Survey, described here. Our 188-orbit Hubble Treasury Program observed 41 clusters at 0.182 ≤ z ≤ 0.972 with Advanced Camera for Surveys (ACS) and WFC3/IR imaging spanning 0.4-1.7 μm. We selected 21 of the most massive clusters known based on Planck PSZ2 estimates and 20 additional clusters based on observed or inferred lensing strength. RELICS observed 46 WFC3/IR pointings (̃200 arcmin²) each with two orbits divided among four filters (F105W, F125W, F140W, and F160W) and ACS imaging as needed to achieve single-orbit depth in each of three filters (F435W, F606W, and F814W). As previously reported by Salmon et al., we discovered over 300 z ̃ 6-10 candidates, including the brightest z ̃ 6 candidates known, and the most distant spatially resolved lensed arc known at z ̃ 10. Spitzer IRAC imaging (945 hr awarded, plus 100 archival, spanning 3.0-5.0 μm) has crucially enabled us to distinguish z ̃ 10 candidates from z ̃ 2 interlopers. For each cluster, two HST observing epochs were staggered by about a month, enabling us to discover 11 supernovae, including 3 lensed supernovae, which we followed up with 20 orbits from our program. Reduced HST images, catalogs, and lens models are available on MAST, and reduced Spitzer images are available on IRSA.

ID: 150904
Type: article
Authors: Di Gennaro, Gabriella; van Weeren, Reinout J.; Andrade-Santos, Felipe; Akamatsu, H.; Randall, Scott W.; Forman, William R.; Kraft, Ralph P.; Brunetti, G.; Dawson, W. A.; Golovich, N.; Jones, Christine
Abstract: We present the results from new deep Chandra (∼410 ks) and Suzaku (∼180 ks) observations of the merging galaxy cluster ZwCl 0008.8+5215 (z = 0.104). Previous radio observations revealed the presence of a double radio relic located diametrically west and east of the cluster center. Using our new Chandra data, we find evidence for the presence of a shock at the location of the western relic, RW, with a Mach number {{ \mathcal M }}_{SX}={1.48}_-0.32^+0.50 from the density jump. We also measure {{ \mathcal M }}_{TX}={2.35}_-0.55^+0.74 and {{ \mathcal M }}_{TX}={2.02}_-0.47^+0.74 from the temperature jump, with Chandra and Suzaku, respectively. These values are consistent with the Mach number estimate from a previous study of the radio spectral index, under the assumption of diffusive shock acceleration ({{ \mathcal M }}_RW}={2.4}_-0.2^+0.4). Interestingly, the western radio relic does not entirely trace the X-ray shock. A possible explanation is that the relic traces fossil plasma from nearby radio galaxies that is reaccelerated at the shock. For the eastern relic we do not detect an X-ray surface brightness discontinuity, despite the fact that radio observations suggest a shock with {{ \mathcal M }}_RE}={2.2}_-0.1^+0.2. The low surface brightness and reduced integration time for this region might have prevented the detection. The Chandra surface brightness profile suggests { \mathcal M }≲ 1.5, while the Suzaku temperature measurements found {{ \mathcal M }}_{TX}={1.54}_-0.47^+0.65. Finally, we also detect a merger-induced cold front on the western side of the cluster, behind the shock that traces the western relic.

ID: 152897
Type: article
Authors: Ge, Chong; Sun, Ming; Liu, Ruo-Yu; Rudnick, Lawrence; Sarazin, Craig; Forman, William; Jones, Christine; Chen, Hao; Liu, Wenhao; Yagi, Masafumi; Boselli, Alessandro; Fossati, Matteo; Gavazzi, Giuseppe
Abstract: Multiwavelength observations show that Abell 1367 (A1367) is a dynamically young cluster, with at least two subclusters merging along the SE-NW direction. With the wide-field XMM-Newton mosaic of A1367, we discover a previously unknown merger shock at the NW edge of the cluster. We estimate the shock Mach number from the density and temperature jumps as M_ρ = 1.21 ± 0.08 and M_T = 1.60 ± 0.07, respectively. This shock region also corresponds to a radio relic discovered with the VLA and GBT, which could be produced by the shock re-acceleration of pre-existing seed relativistic electrons. We suggest that some of the seed relativistic electrons originate from late-type, star-forming galaxies in this region.

ID: 151208
Type: article
Authors: Ge, Chong; Sun, Ming; Rozo, Eduardo; Sehgal, Neelima; Vikhlinin, Alexey; Forman, William; Jones, Christine; Nagai, Daisuke
Abstract: We use a complete sample of 38 richest maxBCG clusters to study the ICM-galaxy scaling relations and the halo mass selection properties of the maxBCG algorithm, based on X-ray and optical observations. The clusters are selected from the two largest bins of optical richness in the Planck stacking work with the maxBCG richness N₂₀₀ ≥ 78. We analyse their Chandra and XMM-Newton data to derive the X-ray properties of the ICM. We then use the distribution of P(X|N), X = T_X, L_X, Y_X, to study the mass selection P(M|N) of maxBCG. Compared with previous works based on the whole richness sample, a significant fraction of blended systems with boosted richness is skewed into this richest sample. Parts of the blended haloes are picked apart by the redMaPPer, an updated red-sequence cluster finding algorithm with lower mass scatter. Moreover, all the optical blended haloes are resolved as individual X-ray haloes, following the established L_X-T_X and L_X-Y_X relations. We further discuss that the discrepancy between ICM-galaxy scaling relations, especially for future blind stacking, can come from several factors, including miscentring, projection, contamination of low-mass systems, mass bias, and covariance bias. We also evaluate the fractions of relaxed and cool core clusters in our sample. Both are smaller than those from SZ or X-ray selected samples. Moreover, disturbed clusters show a higher level of mass bias than relaxed clusters.

ID: 151824
Type: article
Authors: Lyskova, N.; Churazov, E.; Zhang, C.; Forman, William; Jones, Christine; Dolag, K.; Roediger, E.; Sheardown, A.
Abstract: We study a merger of the NGC 4839 group with the Coma cluster using X-ray observations from the XMM-Newton and Chandra telescopes. X-ray data show two prominent features: (i) a long (˜600 kpc in projection) and bent tail of cool gas trailing (towards south-west) the optical centre of NGC 4839, and (ii) a `sheath' region of enhanced X-ray surface brightness enveloping the group, which is due to hotter gas. While at first glance the X-ray images suggest that we are witnessing the first infall of NGC 4839 into the Coma cluster core, we argue that a post-merger scenario provides a better explanation of the observed features and illustrate this with a series of numerical simulations. In this scenario, the tail is formed when the group, initially moving to the south-west, reverses its radial velocity after crossing the apocenter, the ram pressure ceases and the ram pressure-displaced gas falls back towards the centre of the group and overshoots it. Shortly after the apocenter passage, the optical galaxy, dark matter, and gaseous core move in a north-east direction, while the displaced gas continues moving to the south-west. The `sheath' is explained as being due to interaction of the re-infalling group with its own tail of stripped gas mixed with the Coma gas. In this scenario, the shock, driven by the group before reaching the apocenter, has already detached from the group and would be located close to the famous relic to the south-west of the Coma cluster.

ID: 155415
Type: article
Authors: Mahler, Guillaume; Sharon, Keren; Fox, Carter; Coe, Dan; Jauzac, Mathilde; Strait, Victoria; Edge, Alastair; Acebron, Ana; Andrade-Santos, Felipe; Avila, Roberto J.; Bradač, Maruša; Bradley, Larry D.; Carrasco, Daniela; Cerny, Catherine; Cibirka, Nathália; Czakon, Nicole G.; Dawson, William A.; Frye, Brenda L.; Hoag, Austin T.; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Kikuchihara, Shotaro; Lam, Daniel; Livermore, Rachael; Lovisari, Lorenzo; Mainali, Ramesh; Ogaz, Sara; Ouchi, Masami; Paterno-Mahler, Rachel; Roederer, Ian U.; Ryan, Russell E.; Salmon, Brett; Sendra-Server, Irene; Stark, Daniel P.; Toft, Sune; Trenti, Michele; Umetsu, Keiichi; Vulcani, Benedetta; Zitrin, Adi
Abstract: Strong gravitational lensing by clusters of galaxies probes the mass distribution at the core of each cluster and magnifies the universe behind it. MACS J0417.5-1154 at z = 0.443 is one of the most massive clusters known based on weak lensing, X-ray, and Sunyaev-Zel'dovich analyses. Here we compute a strong lens model of MACS J0417 based on Hubble Space Telescope imaging observations collected, in part, by the Reionization Lensing Cluster Survey (RELICS), and recently reported spectroscopic redshifts from the MUSE instrument on the Very Large Telescope (VLT). We measure an Einstein radius of {θ }_E≃ 36^\prime\prime at z = 9 and a mass projected within 200 kpc of {M}_(200{kpc)}={1.78}_-0.03^+0.01× {10}¹⁴ M {}_☉ . Using this model, we measure a ratio between the mass attributed to cluster-member galaxy halos and the main cluster halo of order 1:100. We assess the probability to detect magnified high-redshift galaxies in the field of this cluster, both for comparison with RELICS HST results and as a prediction for the James Webb Space Telescope (JWST) Guaranteed Time Observations upcoming for this cluster. Our lensing analysis indicates that this cluster has similar lensing strength to other clusters in the RELICS program. Our lensing analysis predicts a detection of at least a few z ∼ 6-8 galaxies behind this cluster, at odds with a recent analysis that yielded no such candidates in this field. Reliable strong lensing models are crucial for accurately predicting the intrinsic properties of lensed galaxies. As part of the RELICS program, our strong lensing model produced with the Lenstool parametric method is publicly available through the Mikulski Archive for Space Telescopes.

ID: 155315
Type: article
Authors: Sheardown, Alex; Fish, Thomas M.; Roediger, Elke; Hunt, Matthew; Zuhone, John; Su, Yuanyuan; Kraft, Ralph P.; Nulsen, Paul; Churazov, Eugene; Forman, William; Jones, Christine; Lyskova, Natalya; Eckert, Dominique; De Grandi, Sabrina
Abstract: We show that there is a new class of gas tails-slingshot tails-that form as a subhalo (i.e., a subcluster or early-type cluster galaxy) moves away from the cluster center toward the apocenter of its orbit. These tails can point perpendicular or even opposite to the subhalo direction of motion, not tracing the recent orbital path. Thus, the observed tail direction can be misleading, and we caution against naive conclusions regarding the subhalo's direction of motion based on the tail direction. A head-tail morphology of a galaxy's or subcluster's gaseous atmosphere is usually attributed to ram pressure stripping, and the widely applied conclusion is that gas stripped tail traces the most recent orbit. However, during the slingshot tail stage, the subhalo is not being ram pressure stripped (RPS) and the tail is shaped by tidal forces more than just the ram pressure. Thus, applying a classic RPS scenario to a slingshot tail leads not only to an incorrect conclusion regarding the direction of motion but also to incorrect conclusions regarding the subhalo velocity, expected locations of shear flows, instabilities, and mixing. We describe the genesis and morphology of slingshot tails using data from binary cluster merger simulations and discuss their observable features and how to distinguish them from classic RPS tails. We identify three examples from the literature that are not RPS tails but slingshot tails and discuss other potential candidates.

ID: 154186
Type: article
Authors: Snios, Bradford; Nulsen, Paul E. J.; Kraft, Ralph P.; Cheung, C. C.; Meyer, Eileen T.; Forman, William R.; Jones, Christine; Murray, Stephen S.
Abstract: Chandra HRC observations are investigated for evidence of proper motion and brightness changes in the X-ray jet of the nearby radio galaxy M87. Using images spanning 5 yr, proper motion is measured in the X-ray knotHST-1, with a superluminal apparent speed of 6.3 ± 0.4c, or 24.1 ± 1.6mas yr^-1, and in Knot D, with a speed of 2.4 ± 0.6c. Upper limits are placed on the speeds of the remaining jet features. The X-ray knot speeds are in excellent agreement with existing measurements in the radio, optical, and ultraviolet. Comparing the X-ray results with imagesfrom the Hubble Space Telescope indicates that the X-ray and optical/UV emitting regions co-move. The X-ray knots also vary by up to 73% in brightness, whereas there is no evidence of brightness changes in the optical/UV. Using the synchrotron cooling models, we determine lower limits on magnetic field strengths of ̃ 420 μG and ̃ 230 μG for HST-1and Knot A, respectively, consistent with estimates of the equipartition fields. Together, these results lend strong support to the synchrotron cooling model for Knot HST-1, which requires that its superluminal motion reflects the speed of the relativistic bulk flow in the jet.

ID: 150527
Type: article
Authors: Snios, Bradford; Wykes, Sarka; Nulsen, Paul E. J.; Kraft, Ralph P.; Meyer, Eileen T.; Birkinshaw, Mark; Worrall, Diana M.; Hardcastle, Martin J.; Roediger, Elke; Forman, William R.; Jones, Christine
Abstract: We report results from Chandra observations analyzed for evidence of variability and proper motion in the X-ray jet of Centaurus A. Using data spanning 15 yr, collective proper motion of 11.3 ± 3.3 mas yr^‑1, or 0.68 ± 0.20c, is detected for the fainter X-ray knots and other substructure present within the jet. The three brightest knots (AX1A, AX1C, and BX2) are found to be stationary to an upper limit of 0.10c. Brightness variations up to 27% are detected for several X-ray knots in the jet. For the fading knots, BX2 and AX1C, the changes in spectral slope expected to accompany synchrotron cooling are not found, ruling it out and placing upper limits of ≃80 μG for each of their magnetic field strengths. Adiabatic expansion can account for the observed decreases in brightness. Constraints on models for the origin of the knots are established. Jet plasma overrunning an obstacle is favored as the generator of stationary knots, while moving knots are likely produced either by internal differences in jet speed or the late stages of jet interaction with nebular or cloud material.