Publication Search Results

ID: 159265
Type: article
Authors: Stuardi, C.; Bonafede, A.; Lovisari, L.; Domínguez-Fernández, P.; Vazza, F.; Brüggen, M.; van Weeren, R. J.; de Gasperin, F.
Abstract: Magnetic fields are ubiquitous in galaxy clusters, yet their radial profile, power spectrum, and connection to host cluster properties are poorly known. Merging galaxy clusters hosting diffuse polarized emission in the form of radio relics offer a unique possibility to study the magnetic fields in these complex systems. In this paper, we investigate the intracluster magnetic field in Abell 2345. This cluster hosts two radio relics that we detected in polarization with 1-2 GHz Jansky Very Large Array observations. X-ray XMM-Newton images show a very disturbed morphology. We derived the rotation measure (RM) of five polarized sources within ∼1 Mpc from the cluster centre applying the RM synthesis. Both, the average RM and the RM dispersion radial profiles probe the presence of intracluster magnetic fields. Using the thermal electron density profile derived from X-ray analysis and simulating a 3D magnetic field with fluctuations following a power spectrum derived from magneto-hydrodynamical cosmological simulations, we build mock RM images of the cluster. We constrained the magnetic field profile in the eastern radio relic sector by comparing simulated and observed RM images. We find that, within the framework of our model, the data require a magnetic field scaling with thermal electron density as B(r) ∝ n_e(r). The best model has a central magnetic field (within a 200 kpc radius) of 2.8 $\pm 0.1 \ \mu$ G. The average magnetic field at the position of the eastern relic is $\sim 0.3 \ \mu$ G, a factor 2.7 lower than the equipartition estimate.

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: 158584
Type: article
Authors: Ettori, S.; Lovisari, Lorenzo; Sereno, M.
Abstract: As the end products of the hierarchical process of cosmic structure formation, galaxy clusters present some predictable properties, like those mostly driven by gravity, and some others more affected by astrophysical dissipative processes that can be recovered from observations and that show remarkable universal behaviour once rescaled by halo mass and redshift. However, a consistent picture that links these universal radial profiles and the integrated values of the thermodynamical quantities of the intracluster medium, also quantifying the deviations from the standard self-similar gravity-driven scenario, has to be demonstrated. In this work we use a semi-analytic model based on a universal pressure profile in hydrostatic equilibrium within a cold dark matter halo with a defined relation between mass and concentration to reconstruct the scaling laws between the X-ray properties of galaxy clusters. We also quantify any deviation from the self-similar predictions in terms of temperature dependence of a few physical quantities such as the gas mass fraction, the relation between spectroscopic temperature and its global value, and, if present, the hydrostatic mass bias. This model allows us to reconstruct both the observed profiles and the scaling laws between integrated quantities. We use the Planck Early Sunyaev-Zeldovich sample, a Planck-selected sample of objects homogeneously analysed in X-rays, to calibrate the predicted scaling laws between gas mass, temperature, luminosity, and total mass. Our universal model reproduces well the observed thermodynamic properties and provides a way to interpret the observed deviations from the standard self-similar behaviour, also allowing us to define a framework to modify accordingly the characteristic physical quantities that renormalise the observed profiles. By combining these results with the constraints on the observed Y_SZ - T relation we show how we can quantify the level of gas clumping affecting the studied sample, estimate the clumping-free gas mass fraction, and suggest the average level of hydrostatic bias present.

ID: 158594
Type: article
Authors: Lovisari, Lorenzo; Ettori, S.; Sereno, M.; Schellenberger, Gerrit; Forman, William R.; Andrade-Santos, Felipe; Jones, C.
Abstract: Context. Total mass is arguably the most fundamental property for cosmological studies with galaxy clusters. The individual cluster masses can be obtained with different methods, each with its own biases and limitations. Systematic differences in mass measurements can strongly impact the determination of the hydrostatic bias and of the mass-observable relations, key requirements of many cluster abundance studies.
Aims: We investigate the present differences in the mass estimates obtained through independent X-ray, weak-lensing, and dynamical studies using a large subsample of the Planck-ESZ clusters. We also discuss the implications for mass bias analyses.
Methods: After assessing the systematic differences in the X-ray-derived masses reported by distinct groups, we examine the mass estimates obtained with independent methods and quantify the differences as the mean ratio 1-b = M_HE/M_{WL, dyn}, where HE refers to hydrostatic masses obtained from X-ray observations, WL refers to the results of weak-lensing measurements, and dyn refers to the mass estimates either from velocity dispersion or from the caustic technique. So defined, the 1-b parameter includes all possible astrophysical, observational, and methodological biases in one single value.
Results: Recent X-ray masses reported by independent groups show average differences smaller than ˜10%, posing a strong limit on the systematics that can be ascribed to the differences in the X-ray analysis when studying the hydrostatic bias. The mean ratio between our X-ray masses and the weak-lensing masses in the LC²-single catalog is 1-b = 0.74 ± 0.06, which corresponds to a mass bias of 26 ± 6%, a value insufficient to reconcile the Planck cluster abundance and cosmic microwave background results. However, the mean mass ratios inferred from the WL masses of different projects vary by a large amount, with APEX-SZ showing a bias consistent with zero (1-b = 1.02 ± 0.12), LoCuSS and CCCP/MENeaCS showing a significant difference (1-b = 0.76 ± 0.09 and 1-b = 0.77 ± 0.10, respectively), and WtG pointing to the largest deviation (1-b = 0.61 ± 0.12), which would substantially reduce the tension between the Planck results. Because of small differences between our M - Y_X relation and the one used by the Planck collaboration, our X-ray masses are on average 7% lower (4% at the same physical radius) than the Planck masses and can further reduce the required bias. At odds with the WL results, the dynamical mass measurements show better agreement with the X-ray hydrostatic masses, although there are significant differences when relaxed or disturbed clusters are used. However, the comparison is currently limited by the small sample sizes. Conclisions. The systematic differences between total masses obtained with recent independent X-ray analyses are smaller than those found in previous studies. This shifts the focus to WL and dynamical studies for a better convergence of the level of mass bias. However, the ratios obtained using different mass estimators suggest that there are still systematics that are not accounted for in all the techniques used to recover cluster masses. This prevents the determination of firm constraints on the level of hydrostatic mass bias in galaxy clusters.

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: 157297
Type: article
Authors: Migkas, K.; Schellenberger, Gerrit; Reiprich, T. H.; Pacaud, F.; Ramos-Ceja, M. E.; Lovisari, Lorenzo
Abstract: The isotropy of the late Universe and consequently of the X-ray galaxy cluster scaling relations is an assumption greatly used in astronomy. However, within the last decade, many studies have reported deviations from isotropy when using various cosmological probes; a definitive conclusion has yet to be made. New, effective and independent methods to robustly test the cosmic isotropy are of crucial importance. In this work, we use such a method. Specifically, we investigate the directional behavior of the X-ray luminosity-temperature (L_X-T) relation of galaxy clusters. A tight correlation is known to exist between the luminosity and temperature of the X-ray-emitting intracluster medium of galaxy clusters. While the measured luminosity depends on the underlying cosmology through the luminosity distance D_L, the temperature can be determined without any cosmological assumptions. By exploiting this property and the homogeneous sky coverage of X-ray galaxy cluster samples, one can effectively test the isotropy of cosmological parameters over the full extragalactic sky, which is perfectly mirrored in the behavior of the normalization A of the L_X-T relation. To do so, we used 313 homogeneously selected X-ray galaxy clusters from the Meta-Catalogue of X-ray detected Clusters of galaxies. We thoroughly performed additional cleaning in the measured parameters and obtain core-excised temperature measurements for all of the 313 clusters. The behavior of the L_X-T relation heavily depends on the direction of the sky, which is consistent with previous studies. Strong anisotropies are detected at a ≳4σ confidence level toward the Galactic coordinates (l, b) ∼ (280°, - 20°), which is roughly consistent with the results of other probes, such as Supernovae Ia. Several effects that could potentially explain these strong anisotropies were examined. Such effects are, for example, the X-ray absorption treatment, the effect of galaxy groups and low redshift clusters, core metallicities, and apparent correlations with other cluster properties, but none is able to explain the obtained results. Analyzing 10⁵ bootstrap realizations confirms the large statistical significance of the anisotropic behavior of this sky region. Interestingly, the two cluster samples previously used in the literature for this test appear to have a similar behavior throughout the sky, while being fully independent of each other and of our sample. Combining all three samples results in 842 different galaxy clusters with luminosity and temperature measurements. Performing a joint analysis, the final anisotropy is further intensified (∼5σ), toward (l, b) ∼ (303°, - 27°), which is in very good agreement with other cosmological probes. The maximum variation of D_L seems to be ∼16 ± 3% for different regions in the sky. This result demonstrates that X-ray studies that assume perfect isotropy in the properties of galaxy clusters and their scaling relations can produce strongly biased results whether the underlying reason is cosmological or related to X-rays. The identification of the exact nature of these anisotropies is therefore crucial for any statistical cluster physics or cosmology study.

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: 156987
Type: article
Authors: Xie, C.; van Weeren, Reinout J.; Lovisari, L.; Andrade-Santos, Felipe; Botteon, A.; Brüggen, M.; Bulbul, Esra; Churazov, E.; Clarke, T. E.; Forman, William R.; Intema, H. T.; Jones, C.; Kraft, Ralph P.; Lal, D. V.; Mroczkowski, T.; Zitrin, A.
Abstract: Context. Massive merging galaxy clusters often host diffuse megaparsec- scale radio synchrotron emission. This emission originates from relativistic electrons in the ionized intracluster medium. An important question is how these synchrotron emitting relativistic electrons are accelerated.
Aims: Our aim is to search for diffuse emission in the Frontier Fields clusters Abell S1063 and Abell 370 and characterize its properties. While these clusters are very massive and well studied at some other wavelengths, no diffuse emission has been reported for these clusters so far.
Methods: We obtained 325 MHz Giant Metrewave Radio Telescope (GMRT) and 1-4 GHz Jansky Very Large Array (VLA) observations of Abell S1063 and Abell 370. We complement these data with Chandra and XMM-Newton X-ray observations.
Results: In our sensitive images, we discover radio halos in both clusters. In Abell S1063, a giant radio halo is found with a size of ∼1.2 Mpc. The integrated spectral index between 325 MHz and 1.5 GHz is -0.94 ± 0.08 and it steepens to -1.77 ± 0.20 between 1.5 and 3.0 GHz. This spectral steepening provides support for the turbulent reacceleration model for radio halo formation. Abell 370 hosts a faint radio halo mostly centered on the southern part of this binary merging cluster, with a size of ∼500-700 kpc. The spectral index between 325 MHz and 1.5 GHz is -1.10 ± 0.09. Both radio halos follow the known scaling relation between the cluster mass proxy Y₅₀₀ and radio power, which is consistent with the idea that they are related to ongoing cluster merger events.

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: 154239
Type: article
Authors: Bartalucci, I.; Arnaud, M.; Pratt, G. W.; Démoclès, J.; Lovisari, Lorenzo
Abstract: We study the dynamical state and the integrated total mass profiles of 75 massive (M₅₀₀ > 5 × 10¹⁴ M_☉) Sunyaev-Zeldovich(SZ)-selected clusters at 0.08 ) Sunyaev-Zeldovich(SZ)-selected clusters at 0.08 0.9. Using XMM-Newton imaging observations, we characterise the dynamical state with the centroid shift ⟨w⟩, the concentration C_SB, and their combination, M, which simultaneously probes the core and the large-scale gas morphology. Using spatially resolved spectroscopy and assuming hydrostatic equilibrium, we derive the total integrated mass profiles. The mass profile shape is quantified by the sparsity, that is the ratio of M₅₀₀ to M₂₅₀₀, the masses at density contrasts of 500 and 2500, respectively. We study the correlations between the various parameters and their dependence on redshift. We confirm that SZ-selected samples, thought to most accurately reflect the underlying cluster population, are dominated by disturbed and non-cool core objects at all redshifts. There is no significant evolution or mass dependence of either the cool core fraction or the centroid shift parameter. The M parameter evolves slightly with z, having a correlation coefficient of ρ = -0.2 ± 0.1 and a null hypothesis p-value of 0.01. In the high-mass regime considered here, the sparsity evolves minimally with redshift, increasing by 10% between z 0.55, an effect that is significant at less than 2σ. In contrast, the dependence of the sparsity on dynamical state is much stronger, increasing by a factor of ̃60% from the one third most relaxed to the one third most disturbed objects, an effect that is significant at more than 3σ. This is the first observational evidence that the shape of the integrated total mass profile in massive clusters is principally governed by the dynamical state and is only mildly dependent on redshift. We discuss the consequences for the comparison between observations and theoretical predictions.

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: 154618
Type: article
Authors: Green, Sheridan B.; Ntampaka, Michelle; Nagai, Daisuke; Lovisari, Lorenzo; Dolag, Klaus; Eckert, Dominique; ZuHone, John A.
Abstract: We present a machine-learning approach for estimating galaxy cluster masses, trained using both Chandra and eROSITA mock X-ray observations of 2041 clusters from the Magneticum simulations. We train a random forest (RF) regressor, an ensemble learning method based on decision tree regression, to predict cluster masses using an input feature set. The feature set uses core-excised X-ray luminosity and a variety of morphological parameters, including surface brightness concentration, smoothness, asymmetry, power ratios, and ellipticity. The regressor is cross-validated and calibrated on a training sample of 1615 clusters (80% of sample), and then results are reported as applied to a test sample of 426 clusters (20% of sample). This procedure is performed for two different mock observation series in an effort to bracket the potential enhancement in mass predictions that can be made possible by including dynamical state information. The first series is computed from idealized Chandra-like mock cluster observations, with high spatial resolution, long exposure time (1 Ms), and the absence of background. The second series is computed from realistic-condition eROSITA mocks with lower spatial resolution, short exposures (2 ks), instrument effects, and background photons modeled. We report a 20% reduction in the mass estimation scatter when either series is used in our RF model compared to a standard regression model that only employs core-excised luminosity. The morphological parameters that hold the highest feature importance are smoothness, asymmetry, and surface brightness concentration. Hence these parameters, which encode the dynamical state of the cluster, can be used to make more accurate predictions of cluster masses in upcoming surveys, offering a crucial step forward for cosmological analyses.

ID: 150509
Type: article
Authors: Lovisari, Lorenzo; Reiprich, T. H.
Abstract: We study a sample of 207 nearby galaxy groups and clusters observed with XMM-Newton. Key aspects of this sample include the large size, the high data quality, and the large diversity of cluster dynamical states. We determine the overall metallicity within 0.3 R₅₀₀ and the radial distribution of the metals. On average, we find a mild dependence of the core metallicity with the average temperature of the system in agreement with previous results. However, we identify the cause of this mild dependence to be due to relaxed systems only; disturbed systems do not show this trend, on average. The large scatter observed in this relation is strongly associated with the dynamical state of the systems: relaxed systems have, on average, a higher metallicity in the core than disturbed objects. The radial profiles of relaxed systems are centrally peaked and show a steep decrease with radius, flattening beyond 0.3-0.4 R₅₀₀. The metallicity of disturbed systems is also higher in the centre but at much lower values than what is observed for relaxed objects. This finding is consistent with the picture that cluster mergers mix the abundance distribution by inducing large-scale motions. The scatter of the radial profiles is quite large, but while for relaxed systems it decreases almost monotonically as function of the radius, for disturbed systems it shows a significant boost at large radii. Systems with a central radio source have a flatter profile indicating that central AGNs are an efficient mechanism to uplift and redistribute the metals in the ICM.

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: 155242
Type: article
Authors: Phipps, Frederika; Bogdán, Ákos; Lovisari, Lorenzo; Kovács, Orsolya E.; Volonteri, Marta; Dubois, Yohan
Abstract: Supermassive black holes (BHs) residing in brightest cluster galaxies (BCGs) are overly massive when considering the local relationships between the BH mass and stellar bulge mass or velocity dispersion. Because of the location of these BHs within the cluster, large-scale cluster processes may aid the growth of BHs in BCGs. In this work, we study a sample of 71 galaxy clusters to explore the relationship between the BH mass, stellar bulge mass of the BCG, and the total gravitating mass of the host clusters. Because of difficulties in obtaining dynamically measured BH masses in distant galaxies, we use the Fundamental Plane relationship of BHs to infer their masses. We utilize X-ray observations taken by Chandra to measure the temperature of the intracluster medium, which is a proxy for the total mass of the cluster. We analyze the M _BH-kT and M _BH-M _bulge relationships and establish the best-fitting power laws: {log}}₁₀({M}_BH}/{10}⁹ {M}_☉ ) = -0.35+2.08 {log}}₁₀({kT}/1 {keV}) and {log}}₁₀({M}_BH}/{10}⁹ {M}_☉ ) = -1.09+1.92 {log}}₁₀({M}_bulge}/{10}¹¹ {M}_☉ ). Both relations are comparable with that established earlier for a sample of brightest group/cluster galaxies with dynamically measured BH masses. Although both the M _BH-kT and the M _BH-M _bulge relationships exhibit large intrinsic scatter, on the basis of Monte Carlo simulations, we conclude that dominant fraction of the scatter originates from the Fundamental Plane relationship. We split the sample into cool core and noncool core resembling clusters but do not find statistically significant differences in the M _BH-kT relation. We speculate that the overly massive BHs in BCGs may be due to frequent mergers and cool gas inflows onto the cluster center.

ID: 152906
Type: article
Authors: Ramos-Ceja, M. E.; Pacaud, F.; Reiprich, T. H.; Migkas, K.; Lovisari, Lorenzo; Schellenberger, Gerrit
Abstract: Presently, the largest sample of galaxy clusters selected in X-rays comes from the ROSAT All-Sky Survey (RASS). Although there have been many interesting clusters discovered with the RASS data, the broad point spread function of the ROSAT satellite limits the attainable amount of spatial information for the detected objects. This leads to the discovery of new cluster features when a re-observation is performed with higher-resolution X-ray satellites. Here we present the results from XMM-Newton observations of three clusters: RXC J2306.6-1319, ZwCl 1665, and RXC J0034.6-0208, for which the observations reveal a double or triple system of extended components. These clusters belong to the extremely expanded HIghest X-ray FLUx Galaxy Cluster Sample (eeHIFLUGCS), which is a flux-limited cluster sample (f_{X, 500} ≥ 5 × 10^-12 erg s^-1 cm^-2 in the 0.1-2.4 keV energy band). For each structure in each cluster, we determine the redshift with the X-ray spectrum and find that the components are not part of the same cluster. This is confirmed by an optical spectroscopic analysis of the galaxy members. Therefore, the total number of clusters is actually seven, rather than three. We derive global cluster properties of each extended component. We compare the measured properties to lower-redshift group samples, and find a good agreement. Our flux measurements reveal that only one component of the ZwCl 1665 cluster has a flux above the eeHIFLUGCS limit, while the other clusters will no longer be part of the sample. These examples demonstrate that cluster-cluster projections can bias X-ray cluster catalogues and that with high-resolution X-ray follow-up this bias can be corrected.

ID: 154166
Type: article
Authors: Su, Y.; Kraft, Ralph P.; Nulsen, Paul E. J.; Jones, C.; Maccarone, T. J.; Mernier, F.; Lovisari, Lorenzo; Sheardown, A.; Randall, Scott W.; Roediger, E.; Fish, T. M.; Forman, William R.; Churazov, Eugene
Abstract: The M49 group, residing outside the virial radius of the Virgo cluster, is falling onto the cluster from the south. We report results from deep XMM-Newton mosaic observations of M49. Its hot gas temperature is 0.8 keV at the group center and rises to 1.5 keV beyond the brightest group galaxy (BGG). The group gas extends to radii of ̃300 kpc to the north and south. The observations reveal a cold front ̃20 kpc north of the BGG center and an X-ray-bright stripped tail 70 kpc long and 10 kpc wide to the southwest of the BGG. We argue that the atmosphere of the infalling group was slowed by its encounter with the Virgo cluster gas, causing the BGG to move forward subsonically relative to the group gas. We measure declining temperature and metallicity gradients along the stripped tail. The tail gas can be traced back to the cooler and enriched gas uplifted from the BGG center by buoyant bubbles, implying that active galactic nucleus outbursts may have intensified the stripping process. We extrapolate to a virial radius of 740 kpc and derive a virial mass of 4.6 × 10¹³ M _☉ for the M49 group. Its group atmosphere appears truncated and deficient when compared with isolated galaxy groups of similar temperatures. If M49 is on its first infall to Virgo, the infall region of a cluster could have profound impacts on galaxies and groups that are being accreted onto galaxy clusters. Alternatively, M49 may have already passed through Virgo once.

ID: 150175
Type: article
Authors: Bogdán, Ákos; Lovisari, Lorenzo; Kovács, Orsolya E.; Andrade-Santos, Felipe; Jones, Christine; Forman, William R.; Kraft, Ralph P.
Abstract: Brightest Cluster Galaxies (BCGs) residing in the centers of galaxy clusters are typically quenched giant ellipticals. A recent study hinted that star-forming galaxies with large disks, so-called superluminous spirals and lenticulars, are the BCGs of a subset of galaxy clusters. Based on the existing optical data it was not possible to constrain whether the superluminous disk galaxies reside at the center of galaxy clusters. In this work, we utilize XMM-Newton X-ray observations of five galaxy clusters to map the morphology of the ICM, characterize the galaxy clusters, determine the position of the cluster center, and measure the offset between the cluster center and the superluminous disk galaxies. We demonstrate that one superluminous lenticular galaxy, 2MASX J10405643-0103584, resides at the center of a low-mass (M ₅₀₀ = 10¹⁴ M _⊙) galaxy cluster. This represents the first conclusive evidence that a superluminous disk galaxy is the central BCG of a galaxy cluster. We speculate that the progenitor of 2MASX J10405643-0103584 was an elliptical galaxy, whose extended disk was re-formed due to the merger of galaxies. We exclude the possibility that the other four superluminous disk galaxies reside at the center of galaxy clusters, as their projected distance from the cluster center is 150–1070 kpc, which corresponds to (0.27–1.18)R ₅₀₀. We conclude that these clusters host quiescent massive elliptical galaxies at their center.

ID: 145761
Type: article
Authors: Bogdán, Ákos; Lovisari, Lorenzo; Volonteri, Marta; Dubois, Yohan
Abstract: Supermassive black holes (BHs) residing in the brightest cluster galaxies are over-massive relative to the stellar bulge mass or central stellar velocity dispersion of their host galaxies. As BHs residing at the bottom of the galaxy cluster's potential well may undergo physical processes that are driven by the large-scale characteristics of the galaxy clusters, it is possible that the growth of these BHs is (indirectly) governed by the properties of their host clusters. In this work, we explore the connection between the mass of BHs residing in the brightest group/cluster galaxies (BGGs/BCGs) and the virial temperature, and hence total gravitating mass, of galaxy groups/clusters. To this end, we investigate a sample of 17 BGGs/BCGs with dynamical BH mass measurements and utilize XMM-Newton X-ray observations to measure the virial temperatures and infer the {M}₅₀₀ mass of the galaxy groups/clusters. We find that the {M}_{BH}{--}{kT} relation is significantly tighter and exhibits smaller scatter than the {M}_{BH}{--}{M}_{bulge} relations. The best-fitting power-law relations are {{log}}₁₀({M}_{BH}/{10}⁹ {M}_o )=0.20+1.74{{log}}₁₀({kT}/1 {keV}) and {{log}}₁₀({M}_{BH}/{10}⁹ {M}_o ) = -0.80+1.72{{log}}₁₀({M}_{bulge}/{10}¹¹ {M}_o ). Thus, the BH mass of BGGs/BCGs may be set by physical processes that are governed by the properties of the host galaxy group/cluster. These results are confronted with the Horizon-AGN simulation, which reproduces the observed relations well, albeit the simulated relations exhibit notably smaller scatter.

ID: 148987
Type: article
Authors: Cibirka, Nathália; Acebron, Ana; Zitrin, Adi; Coe, Dan; Agulli, Irene; Andrade-Santos, Felipe; Bradac, Marusa; Frye, Brenda; Livermore, Rachael C.; Mahler, Guillaume; Salmon, Brett; Sharon, Keren; Trenti, Michele; Umetsu, Keiichi; Avila, Roberto; Bradley, Larry; Carrasco, Daniela; Cerny, Catherine; Czakon, Nicole G.; Dawson, William A.; Hoag, Austin T.; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Kikuchihara, Shotaro; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Oesch, Pascal A.; Ogaz, Sara; Ouchi, Masami; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Ryan, Russell E.; Sendra-Server, Irene; Stark, Daniel P.; Strait, Victoria; Toft, Sune; Vulcani, Benedetta
Abstract: We present a strong lensing analysis of four massive galaxy clusters imaged with the Hubble Space Telescope in the Reionization Lensing Cluster Survey. We use a light-traces-mass technique to uncover sets of multiple images and constrain the mass distribution of the clusters. These mass models are the first published for Abell S295 and MACS J0159.8-0849 and are improvements over previous models for Abell 697 and MACS J0025.4-1222. Our analysis for MACS J0025.4-1222 and Abell S295 shows a bimodal mass distribution supporting the merger scenarios proposed for these clusters. The updated model for MACS J0025.4-1222 suggests a substantially smaller critical area than previously estimated. For MACS J0159.8-0849 and Abell 697, we find a single peak and relatively regular morphology revealing fairly relaxed clusters. Despite being less prominent lenses, three of these clusters seem to have lensing strengths, i.e., cumulative area above certain magnification, similar to those of the Hubble Frontier Fields clusters (e.g., A(mu > 5) ~ 1--3 arcmin², A(mu > 10) ~ 0.5--1.5 arcmin²), which in part can be attributed to their merging configurations. We make our lens models publicly available through the Mikulski Archive for Space Telescopes. Finally, using Gemini-N/GMOS spectroscopic observations, we detect a single emission line from a high-redshift J ₁₂₅ ~= 25.7 galaxy candidate lensed by Abell 697. While we cannot rule out a lower-redshift solution, we interpret the line as Lyalpha at z = 5.800 ± 0.001, in agreement with its photometric redshift and dropout nature. Within this scenario, we measure a Lyalpha rest-frame equivalent width of 52 ± 22 Å and an observed Gaussian width of 117 ± 15 km s^-1.