The behaviour of dark matter associated with 4 bright cluster galaxies in the 10kpc core of Abell 3827
Richard Massey, Liliya Williams, Renske Smit, Mark Swinbank, Thomas Kitching, David Harvey, Mathilde Jauzac, Holger Israel, Douglas Clowe, Alastair Edge, Matt H… 展开作者
Richard Massey, Liliya Williams, Renske Smit, Mark Swinbank, Thomas Kitching, David Harvey, Mathilde Jauzac, Holger Israel, Douglas Clowe, Alastair Edge, Matt Hilton, Eric Jullo, Adrienne Leonard, Jori Liesenborgs, Julian Merten, Irshad Mohammed, Daisuke Nagai, Johan Richard, Andrew Robertson, Prasenjit Saha, Rebecca Santana, John Stott, Eric Tittley
Galaxy cluster Abell 3827 hosts the stellar remnants of four almost equally bright elliptical galaxies within a core of radius 10kpc. Such corrugation of the stellar distribution is very rare, and suggests recent formation by several simultaneous mergers. We map the distribution of associated dark matter, using new Hubble Space Telescope imaging and VLT/MUSE integral field spectroscopy of a gravitationally lensed system threaded through the cluster core. We find that each of the central galaxies retains a dark matter halo, but that (at least) one of these is spatially offset from its stars. The best-constrained offset is 1.62+/-0.48kpc, where the 68% confidence limit includes both statistical error and systematic biases in mass modelling. Such offsets are not seen in field galaxies, but are predicted during the long infall to a cluster, if dark matter self-interactions generate an extra drag force. With such a small physical separation, it is difficult to definitively rule out astrophysical effects operating exclusively in dense cluster core environments - but if interpreted solely as evidence for self-interacting dark matter, this offset implies a cross-section sigma/m=(1.7+/-0.7)x10^{-4}cm^2/g x (t/10^9yrs)^{-2}, where t is the infall duration.
New high-resolution r band imaging of the brightest cluster galaxy (BCG) in Abell 85 (Holm 15A) was obtained using the Gemini Multi Object Spectrograph. These data were taken with the aim of deriving an accurate surface brightness profile of the BCG of Abell 85, in particular its central region. The new Gemini data show clear evidence of a previously unreported nuclear emission that is evident as a distinct light excess in the central kiloparsec of the surface brightness profile. We find that the light profile is never flat nor does it present a downward trend towards the center of the galaxy.…
The study of low surface brightness light in large, deep imaging surveys is still uncharted territory as automated data reduction pipelines over-subtract or eliminate this light. Using archival data of the Abell 85 cluster of galaxies taken with Hyper Suprime-Cam on the Subaru Telescope, we show that using careful data processing can unveil the diffuse light within the cluster, the intracluster light. We reach surface brightness limits of $μ_{g}^{limit}$(3$σ$, 10"x10") = 30.9 mag/arcsec$^2$, and $μ_{i}^{limit}$(3$σ$, 10"x10") = 29.7 mag/arcsec$^2$. We measured the radial surface brightness pro…
We report the discovery of twin radio relics in the outskirts of the low-mass merging galaxy cluster Abell 168 (redshift=0.045). One of the relics is elongated with a linear extent $\sim$ 800 kpc, a projected width of $\sim$ 80 kpc and is located $\sim$ 900 kpc toward the north of the cluster center, oriented roughly perpendicular to the major axis of the X-ray emission. The second relic is ring-shaped with a size $\sim$ 220 kpc and is located near the inner edge of the elongated relic at a distance of $\sim$ 600 kpc from the cluster center. These radio sources were imaged at 323 and 608 MHz w…
Context: The shape of the mass density profiles of cosmological halos informs us of the nature of DM and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition to predictions derived from numerical simulations of CDM. Aims: We determine the inner slope of the DM density profile of a massive cluster of galaxies, Abell S1063 (RXC J2248.7$-$4431) at $z=0.35$, with a dynamical analysis based on an extensive spectroscopic campaign carried out with the VIMOS and MUSE spectrographs at the ESO VLT. This new data set provide…
We present a detailed analysis of a cool-core galaxy cluster Abell 3017, at a redshift of z=0.219, which has been identified to be merging with its companion cluster Abell 3016. This study has made use of X-ray Chandra, UV (GALEX), optical (ESO/VLT), mid-infrared (WISE), and radio uGMRT observations of this cluster. Using various image processing techniques, such as unsharp masking, 2-d fits using Beta models, contour binning and the use of surface brightness profiles, we show the existence of a pair of X-ray cavities, at a projected distance of $\sim$20'' (70 kpc) and $\sim$16'' (57 kpc), res…
Multifrequency studies of galaxy clusters are crucial for inferring their dynamical states and physics. Moreover, these studies allow us to investigate cluster-embedded sources, whose evolution is affected by the physical and dynamical condition of the cluster itself. So far, these kinds of studies have been preferentially conducted on clusters visible from the northern hemisphere due to the high-fidelity imaging capabilities of ground-based radio interferometers located there. In this paper, we conducted a multifrequency study of the poorly known galaxy cluster Abell 3718. We investigated the…
We investigate the origin and nature of the multiple sloshing cold fronts in the core of Abell 496 by direct comparison between observations and dedicated hydrodynamical simulations. Our simulations model a minor merger with a 4{\times}10^13M{\circ} subcluster crossing A496 from the south-west to the north-north-east, passing the cluster core in the south-east at a pericentre distance 100 to a few 100 kpc about 0.6 to 0.8 Gyr ago. The gas sloshing triggered by the merger can reproduce almost all observed features, e.g. the characteristic spiral-like brightness residual distribution in the clus…
We present the first X-ray dedicated study of the galaxy cluster A795 and of the Fanaroff-Riley Type 0 hosted in its brightest cluster galaxy. Using an archival 30 ks \textit{Chandra} observation we study the dynamical state and cooling properties of the intracluster medium, and we investigate whether the growth of the radio galaxy is prevented by the surrounding environment. We discover that A795 is a weakly cool core cluster, with an observed mass deposition rate $\lessapprox 14\,$ M$_{\odot}$yr$^{-1}$ in the cooling region (central $\sim$66 kpc). In the inner $\sim$ 30 kpc we identify two p…
Abell 2146 consists of two galaxy clusters that have recently collided close to the plane of the sky, and it is unique in showing two large shocks on $\textit{Chandra X-ray Observatory}$ images. With an early stage merger, shortly after first core passage, one would expect the cluster galaxies and the dark matter to be leading the X-ray emitting plasma. In this regard, the cluster Abell 2146-A is very unusual in that the X-ray cool core appears to lead, rather than lag, the Brightest Cluster Galaxy (BCG) in their trajectories. Here we present a strong lensing analysis of multiple image systems…
If dark matter has a non-zero self-interaction cross-section, then dark matter halos of individual galaxies in cluster cores should experience a drag force from the ambient dark matter of the cluster, which will not affect the stellar components of galaxies, and thus will lead to a separation between the stellar and dark matter. If the cross-section is only a few decades below its current astrophysically determined upper limit, then kpc-scale separations should result. However, such separations will be observable only under very favorable conditions. Abell 3827 is a nearby late stage cluster m…
We report on the detection of a giant radio halo in the cluster Abell 3404 as well as confirmation of the radio halo observed in Abell 141 (with linear extents $\sim 770$ kpc and $\sim 850$ kpc, respectively). We use the Murchison Widefield Array (MWA) in conjunction with the Australian Square Kilometre Array Pathfinder (ASKAP) and the Australia Telescope Compact Array (ATCA) to characterise the emission and intervening radio sources from $\sim100$-$1000$ MHz; power law models are fit to the spectral energy distributions with spectral indices $α_{88}^{1110} = -1.66 \pm 0.07$ and $α_{88}^{944} …
We study the dynamics of Abell 370 (A370), a highly massive Hubble Frontier Fields galaxy cluster, using self-consistent three-dimensional N-body/hydrodynamical simulations. Our simulations are constrained by X-ray, optical spectroscopic and gravitational lensing, and Sunyaev-Zel'dovich (SZ) effect observations. Analyzing archival Chandra observations of A370 and comparing the X-ray morphology to the latest gravitational lensing mass reconstruction, we find offsets of ~30 kpc and ~100 kpc between the two X-ray surface brightness peaks and their nearest mass surface density peaks, suggesting th…
We present integral field spectroscopy of the nebular line emission in a sample of 9 brightest cluster galaxies (BCGs). The sample was chosen to probe both cooling flow and non-cooling flow clusters, as well as a range of cluster X-ray luminosities. The line emission morphology and velocity gradients suggest a great diversity in the properties of the line emitting gas. While some BGCs show evidence for filamentary or patchy emission (Abell 1060, Abell 1668 and MKW3s), others have extended emission (Abell 1204, Abell 2199), while still others have centrally concentrated emission (Abell 2052). W…
We present the evidence for the existence of substructure in the cold front cluster A2554 based on a 20.14 ks Chandra observation. Using centroid shift and X-ray brightness concentration parameters, we confirm that A2554 is a dynamically disturbed system. We detect two dominant structures; a main cluster at z = 0.1108 and a foreground northern substructure at z = 0.1082. The analysis reveals an X-ray surface brightness edge at r \simeq 60 kpc from the cluster core. The thermodynamical profiles across the edge are ruling out the shock scenario. The temperature jump (from \sim 6 keV to \sim 10 k…
Cluster faint low surface brightness galaxies (fLSBs) are difficult to observe. Consequently, their origin, physical properties and number density are not well known. After a first search for fLSBs in the highly substructured Coma cluster, we present here a search for fLSBs in Abell 496. This cluster appears to be much more relaxed than Coma, but is embedded in a large scale filament of galaxies. Our aim is to compare the properties of fLSBs in these two very different clusters, to search for environmental effects. Based on deep CFHT/Megacam images in the u*, g', r' and i' bands, we selected g…
We use the Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) strong lensing image catalog of the merging galaxy cluster Abell 370 to obtain a mass model using the free-form lens inversion algorithm GRALE. The improvement of the strong lensing data quality results in a lens plane rms of only 0.45 arcsec, about a factor of two lower than that of our existing HFF v4 reconstruction. We attribute the improvement to spectroscopic data and use of the full reprocessed HST mosaics. In our reconstructed mass model, we found indications of three distinct mass features in Abell 370: (i) …
We measure alignments on scales of 1 Mpc $h^{-1}_{71}$ for galaxies in Abell 1689 ($z=0.18$) from an existing Hubble Space Telescope mosaic. We find evidence of galaxy alignment in the inner 500 $h^{-1}_{71}$ kpc. The alignment appears to be stronger towards the centre and is mostly present among the fainter galaxies, while bright galaxies are unaligned. This is consistent with a model where alignments originate from tidal locking.
We present the analysis of deep optical imaging of the galaxy cluster Abell 133 with the IMACS instrument on Magellan. Our multi-band photometry enables stellar mass measurements in the cluster member galaxies down to a mass limit of $M_\star=3\times10^8\,M_\odot$ ($\approx 0.1$ of the Large Magellanic Cloud stellar mass). We observe a clear difference in the spatial distribution of large and dwarf galaxies within the cluster. Modeling these galaxies populations separately, we can confidently track the distribution of stellar mass locked in the galaxies to the cluster's virial radius. The exte…
Abell 3667 is among the most well-studied galaxy clusters in the Southern Hemisphere. It is known to host two giant radio relics and a head-tail radio galaxy as the brightest cluster galaxy. Recent work has suggested the additional presence of a bridge of diffuse synchrotron emission connecting the North-Western radio relic with the cluster centre. In this work, we present full-polarization observations of Abell 3667 conducted with the Karoo Array Telescope at 1.33 and 1.82 GHz. Our results show both radio relics as well as the brightest cluster galaxy. We use ancillary higher-resolution data …
We report the discovery of seven strongly lensed Lyman break galaxy (LBG) candidates at z~7 detected in Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) imaging of Abell 1703. The brightest candidate, called A1703-zD1, has an observed (lensed) magnitude of 24.0 AB (26 sigma) in the WFC3/IR F160W band, making it 0.2 magnitudes brighter than the z_850-dropout candidate recently reported behind the Bullet Cluster and 0.7 magnitudes brighter than the previously brightest known z~7.6 galaxy, A1689-zD1. With a cluster magnification of ~9, this source has an intrinsic magnitude of H_160 = 26.4…
We present the results of deep Chandra and XMM-Newton X-ray imaging and spatially-resolved spectroscopy of Abell 2256, a nearby (z=0.058) galaxy cluster experiencing multiple mergers and displaying a rich radio morphology dominated by a large relic. The X-ray data reveals three subclusters: (i) the `main cluster'; (ii) the remnant of an older merger in the east of the cluster with a ~ 600 kpc long tail; (iii) a bright, bullet-like, low-entropy infalling system, with a large line-of-sight velocity component. The low-entropy system displays a 250 kpc long cold front with a break and an intriguin…
We present new low-frequency ($ν= 88$-216 MHz) observations of the complex merging galaxy cluster Abell 3266. These new observations are taken with the Murchison Widefield Array (MWA) in its Phase II 'extended', long-baseline configuration, offering the highest-resolution low-frequency view of the cluster to date. We report on the detection of four steep spectrum ($α\lesssim -1$ for $S_ν\propto ν^α$) extended radio sources within the cluster. We confirm the detection of a $\sim 570$ kpc radio relic to the south of the cluster, and a possible bridge of emission connecting the relic to the clust…
Cluster mergers are an important laboratory for studying the behaviour of dark matter (DM) and intracluster gas. There are dissociative collisions that can separate the intracluster gas from the DM. Abell 2034 presents clear dissociative features observed by X-rays and gravitational lensing. The cluster, at $z$ = 0.114, consists of two substructures with mass ratio of about 1:2.2, separated by $\sim$720 kpc. The X-ray emission peak is offcentred from the south DM peak by $\sim$350 kpc. Using N-body hydrodynamical simulations, we aim to reconstruct the dynamic history of the collision, reproduc…
We present the results of deep Chandra, XMM-Newton and Suzaku observations of the nearby galaxy cluster Abell 85, which is currently undergoing at least two mergers, and in addition shows evidence for gas sloshing which extends out to r ~ 600 kpc. One of the two infalling subclusters, to the south of the main cluster center, has a dense, X-ray bright cool core and a tail extending to the southeast. The northern edge of this tail is strikingly smooth and sharp (narrower than the Coulomb mean free path of the ambient gas) over a length of 200 kpc, while toward the southwest the boundary of the t…
Thermal gas in the center of galaxy clusters can show substantial motions that generate surface-brightness and temperature discontinuities known as cold fronts. The motions may be triggered by minor or off-axis mergers that preserve the cool core of the system. The dynamics of the thermal gas can also generate radio emission from the intra-cluster medium (ICM) and impact the evolution of clusters' radio sources. We aim to study the central region of Abell 1775, a system in an ambiguous dynamical state at $z=0.072$ which is known to host an extended head-tail radio galaxy, with the goal of inve…
We report on the discovery of three bright, strongly-lensed objects behind Abell 1703 and CL0024+16 from a dropout search over 25 square arcminutes of deep NICMOS data, with deep ACS optical coverage. They are undetected in the deep ACS images below 8500 A and have clear detections in the J and H bands. Fits to the ACS, NICMOS and IRAC data yield robust photometric redshifts in the range z~6-7 and largely rule out the possibility that they are low-redshift interlopers. All three objects are extended, and resolved into a pair of bright knots. The bright i-band dropout in Abell 1703 has an H-ban…
Based on HST and MUSE data, we probe the stellar and gas properties (i.e. kinematics, stellar mass, star formation rate) of the radio-loud brightest cluster galaxy (BCG) located at the centre of the X-ray luminous cool core cluster Abell 2667 (z = 0.2343). The bi-dimensional modelling of the BCG surface brightness profile reveals the presence of a complex system of substructures extending all around the galaxy. Clumps of different size and shape plunged into a more diffuse component constitute these substructures, whose intense 'blue' optical colour hints to the presence of a young stellar pop…
We present a new analysis of very deep Chandra observations of the galaxy cluster Abell 1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to resolve the thermodynamic structure of the Intracluster Medium (ICM) on length scales of ~ 1 kpc near the cool core. We find several previously unresolved structures, including a high pressure feature to the north of the BCG that appears to arise from the bulk motion of Abell 1795's cool core. To the south of the cool core, we find low temperature (~ 3 keV), diffuse ICM gas extending for distances of ~ 50 kpc spatially coincident with previou…
Clusters of galaxies are excellent laboratories for studying recurring nuclear activity in galactic nuclei since their hot gaseous medium can vastly prolong the detectability of their radio lobes via better confinement. We report here a multi-band study of the sparsely studied galaxy cluster Abell 980, based on our analysis of {\it{Chandra}} X-ray and the GMRT (150 and 325 MHz) and EVLA (1.5 GHz) radio archival data, revealing an unusually rich phenomenology. It is shown to be a quasi-relaxed cluster with a cool core ($T\sim4.2$ keV) surrounded by a hot and extensive intracluster medium (ICM) …
We present a new study of the merger dynamics of Abell~1775 by analyzing the high-quality Chandra and XMM-Newton archival data. We confirm/identify an arc-shaped edge (i.e., the head) at $\sim48$~kpc west of the X-ray peak, a split cold gas tail that extends eastward to $\sim163$~kpc, and a plume of spiral-like X-ray excess (within about $81-324$~kpc northeast of the cluster core) that connects to the end of the tail. The head, across which the projected gas temperature rises outward from $3.39_{-0.18}^{+0.28}$~keV to $5.30_{-0.43}^{+0.54}$~keV, is found to be a cold front with a Mach number o…
We present a study of the population of bright early-type dwarf galaxies in the multiple-cluster system Abell 901/902. We use data from the STAGES survey and COMBO-17 to investigate the relation between the color and structural properties of the dwarfs and their location in the cluster. The definition of the dwarf sample is based on the central surface brightness and includes galaxies in the luminosity range -16 >= M_B >~-19 mag. Using a fit to the color magnitude relation of the dwarfs, our sample is divided into a red and blue subsample. We find a color-density relation in the projected radi…
We present here our results on a complete sample of Brightest Cluster Galaxies (BCGs) in nearby Abell Clusters (distance class <3). Combined with data from the literature, we provide parsec scale information for 34 BCGs. We found that also radio loud BCGs have core structures very complex (e.g. 4C 26.42 in Abell 1795). Moreover, we noted a possible dichotomy between BCGs in cool-core clusters and those in non-cool-core clusters. Among resolved sources, those in cool-core clusters tend to have two-sided parsec scale jets, while those in less relaxed clusters have predominantly one-sided parsec …
The intracluster plasma of Abell 2052 exhibits in X-rays a spiral structure extending more than 250 kpc, which is comprised of cool gas. This feature is understood to be the result of gas sloshing caused by the off-axis collision with a smaller subcluster. We aim to recover the dynamical history of Abell 2052 and to reproduce the broad morphology of the spiral feature. To this end, we perform hydrodynamical $N$-body simulations of cluster collisions. We obtain two regimes that adequately reproduce the desired features. The first scenario is a close encounter and a recent event (0.8 Gyr since p…
(Abstract abridged) The Abell 222 and 223 clusters are located at an average redshift z ~ 0.21 and are separated by 0.26 deg. Signatures of mergers have been previously found in these clusters, both in X-rays and at opticalwavelengths, thus motivating our study. In X-rays, they are relatively bright, and Abell 223 shows a double structure. A filament has also been detected between the clusters both at optical and X-ray wavelengths. We analyse the optical properties of these two clusters based on deep imaging in two bands, derive their galaxy minosity functions (GLFs) and correlate these proper…
We present a new 400 ks Chandra X-ray observation of the merging galaxy cluster Abell 2146. This deep observation reveals detailed structure associated with the major merger event including the Mach M=2.3+/-0.2 bow shock ahead of the dense, ram pressure stripped subcluster core and the first known example of an upstream shock in the ICM (M=1.6+/-0.1). By measuring the electron temperature profile behind each shock front, we determine the timescale for the electron population to thermally equilibrate with the shock-heated ions. We find that the temperature profile behind the bow shock is consis…
Observed galaxy clusters often exhibit X-ray morphologies suggestive of recent interaction with an infalling subcluster. Abell 3376 is a nearby (z=0.046) massive galaxy cluster whose bullet-shaped X-ray emission indicates that it may have undergone a recent collision. It displays a pair of Mpc-scale radio relics and its brightest cluster galaxy is located 970 h_70^-1 kpc away from the peak of X-ray emission, where the second brightest galaxy lies. We attempt to recover the dynamical history of Abell 3376. We perform a set of N-body adiabatic hydrodynamical simulations using the SPH code Gadget…
The brightest cluster galaxy (BCG) in the Abell 1664 cluster is unusually blue and is forming stars at a rate of ~ 23 M_{\sun} yr^{-1}. The BCG is located within 5 kpc of the X-ray peak, where the cooling time of 3.5x10^8 yr and entropy of 10.4 keV cm^2 are consistent with other star-forming BCGs in cooling flow clusters. The center of A1664 has an elongated, "bar-like" X-ray structure whose mass is comparable to the mass of molecular hydrogen, ~ 10^{10} M_{\sun} in the BCG. We show that this gas is unlikely to have been stripped from interloping galaxies. The cooling rate in this region is ro…
We have made mass maps of three strong-lensing clusters, Abell 3827, Abell 2218 and Abell 1689, in order to test for mass-light offsets. The technique used is GRALE, which enables lens reconstruction with minimal assumptions, and specifically with no information about the cluster light being given. In the first two of these clusters, we find local mass peaks in the central regions that are displaced from the nearby galaxies by a few to several kpc. These offsets {\em could\/} be due to line of sight structure unrelated to the clusters, but that is very unlikely, given the typical levels of cha…
Based on a detailed analysis of the high-quality Chandra, XMM-Newton, and Suzaku data of the X-ray bright cluster of galaxies Abell 1795, we report clear evidence for a two-phase intracluster medium (ICM) structure, which consists of a cool (with a temperature T = 2.0-2.2 keV) and a hot (T = 5.0-5.7 keV) component that coexist and dominate the X-ray emission at least in the central 80 kpc. A third weak emission component (T = 0.8 keV) is also detected within the innermost 144 kpc and is ascribed to a portion of inter-stellar medium (ISM) of the cD galaxy. Deprojected spectral analysis reveals …
Diffuse radio emission in galaxy clusters, and their connection with cluster mergers, are still debated. We seek to explore the internal dynamics of the radio halo cluster Abell 545. This cluster is also peculiar for hosting in its center a very bright, red, diffuse intracluster light due to an old, stellar population, so bright to be named as "star pile". Our analysis is based on redshift data for 110 galaxies. We identify 95 cluster members and analyze the cluster internal dynamics by combining galaxy velocities and positions. We also use both photometric and X-ray data. We estimate the clus…
We present a new mass estimate of a well-studied gravitational lensing cluster, Abell 1689, from deep Chandra observations with a total exposure of 200 ks. Within r=200 h-1 kpc, the X-ray mass estimate is systematically lower than that of lensing by 30-50%. At r>200 h-1 kpc, the mass density profiles from X-ray and weak lensing methods give consistent results. The most recent weak lensing work suggest a steeper profile than what is found from the X-ray analysis, while still in agreement with the mass at large radii. Previous studies have suggested that cooler small-scale structures can bias X-…
Off-axis collisions between galaxy clusters may induce the phenomenon of sloshing, causing dense gas to be dragged from the cool core of a cluster, resulting in a spiral of enhanced X-ray emission. Abell 2199 displays signatures of sloshing in its core and it is possible that the orbital plane of the collision is seen nearly edge-on. We aim to evaluate whether the features of Abell 2199 can be explained by a sloshing spiral seen under a large inclination angle. To address this, we perform tailored hydrodynamical $N$-body simulations of a non-frontal collision with a galaxy group of $M_{200}=1.…
The Abell 780 cluster, better known as the Hydra A cluster, has been thouroughly analyzed in X-rays. However, little is known on its optical properties. We derive the galaxy luminosity function (GLF) in this apparently relaxed cluster, and search for possible environmental effects by comparing the GLFs in various regions, and by looking at the galaxy distribution at large scale around Abell 780. Our study is based on optical images obtained with the ESO 2.2m telescope and WFI camera in the B and R bands, covering a total region of 67.22x32.94 arcmin^2, or 4.235x2.075 Mpc^2 for a cluster redshi…
Identification of Abell 3120 as a galaxy cluster has recently been questioned with alternative suggestions including: a fossil remnant of a group merger, non-thermal emission from a radio galaxy, and projected emission from of a filamentary string of galaxies. We report on our analysis of the Chandra observation and evaluate these hypotheses based on our results. Abell 3120 shows X-ray emission extending 158 kpc, well beyond the central galaxy. The spatial distribution of X-rays in the core more closely follows the radio emission showing a jet-like structure extending to the north that is misa…
We present the first flexion-focused gravitational lensing analysis of the first of the strong-lensing "cosmic telescope" galaxy clusters, observed as part of the Hubble Frontier Fields initiative. Using HST observations of Abell 2744 (z = 0.308), we apply a modified Analytic Image Model (AIM) technique to measure source galaxy flexion and shear values at a final number density of 82 arcmin$^{-2}$. By using flexion data alone we are able to identify the primary mass structure aligned along the heart of the cluster in addition to a major substructure peak offset 1.43' from the cluster core. We …
We present new Chandra X-ray observations of the brightest cluster galaxy (BCG) in the cool core cluster Abell 2597. The data reveal an extensive kpc-scale X-ray cavity network as well as a 15 kpc filament of soft-excess gas exhibiting strong spatial correlation with archival VLA radio data. In addition to several possible scenarios, multiwavelength evidence may suggest that the filament is associated with multiphase (10^3 - 10^7 K) gas that has been entrained and dredged-up by the propagating radio source. Stemming from a full spectral analysis, we also present profiles and 2D spectral maps o…
Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z=0.306), which reveal the presence of a shock front 1.5 Mpc East of the cluster core. The surface-brightness jump coincides with the position of a known radio relic. Although the surface-brightness jump indicates a weak shock with a Mach number $\mathcal{M}=1.7_{-0.3}^{+0.5}$, the plasma in the post-shock region has been heated to a very high temperature ($\sim13$ keV) by the pa…
Combined LOFAR-uGMRT analysis of the diffuse radio emission in the massive clusters Abell 773 and Abell 1351
Istituto Nazionale di Astrofisica (INAF) - Istituto di Radioastronomia (IRA)（意大利国家天体物理研究所-射电天文研究所）；Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna（博洛尼亚大学物理与天文学系）；Istituto Nazionale di Astrofisica – Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF)（意大利国家天体物理研究所-空间天体物理学与宇宙物理学研究所）；University of Kashmir（克什米尔大学）；Hamburger Sternwarte, Universität Hamburg（汉堡天文台，汉堡大学）
We report ALMA Early Science observations of the Abell 1835 brightest cluster galaxy (BCG) in the CO (3-2) and CO (1-0) emission lines. We detect 5E10 solar masses of molecular gas within 10 kpc of the BCG. Its velocity width of ~130 km/s FWHM is too narrow to be supported by dynamical pressure. The gas may instead be supported in a rotating, turbulent disk oriented nearly face-on. The disk is forming stars at a rate of 100-180 solar masses per year. Roughly 1E10 solar masses of molecular gas is projected 3-10 kpc to the north-west and to the east of the nucleus with line of sight velocities l…
We report ALMA Early Science CO(1-0) and CO(3-2) observations of the brightest cluster galaxy (BCG) in Abell 1664. The BCG contains 1.1x10^{10} solar masses of molecular gas divided roughly equally between two distinct velocity systems: one from -250 to +250 km/s centred on the BCG's systemic velocity and a high velocity system blueshifted by 570 km/s with respect to the systemic velocity. The BCG's systemic component shows a smooth velocity gradient across the BCG center with velocity proportional to radius suggestive of solid body rotation about the nucleus. However, the mass and velocity st…
Abell 1351 is a massive merging cluster that hosts a giant radio halo and a bright radio edge blended in the halo. In this paper, we present the first ever spectral analysis of this cluster using GMRT 610 MHz and VLA 1.4 GHz archival data and discuss the radio edge property. Using \textit{Chandra} data, we report the first tentative detection of shock front at the location of the edge in A1351 with discontinuities in both X-ray surface brightness and temperature. Our analysis strengthens the previous claim of the detected "edge" being a high luminosity radio relic. The radio relic has an integ…
We extend our analyses of the dark matter (DM) distribution in relaxed clusters to the case of Abell 383, a luminous X-ray cluster at z=0.189 with a dominant central galaxy and numerous strongly-lensed features. Following our earlier papers, we combine strong and weak lensing constraints secured with Hubble Space Telescope and Subaru imaging with the radial profile of the stellar velocity dispersion of the central galaxy, essential for separating the baryonic mass distribution in the cluster core. Hydrostatic mass estimates from Chandra X-ray observations further constrain the solution. These …
We present the analysis of a deep Chandra observation of a ~2L_* late-type galaxy, ESO 137-002, in the closest rich cluster A3627. The Chandra data reveal a long (>40 kpc) and narrow tail with a nearly constant width (~3 kpc) to the southeast of the galaxy, and a leading edge ~1.5 kpc from the galaxy center on the upstream side of the tail. The tail is most likely caused by the nearly edge-on stripping of ESO 137-002's ISM by ram pressure, compared to the nearly face-on stripping of ESO 137-001 discussed in our previous work. Spectral analysis of individual regions along the tail shows that th…
We measure the local correlation between radio emission and Compton-$y$ signal across two galaxy clusters, Abell~399 and Abell~401, using maps from the Low-Frequency Array (LOFAR) and the Atacama Cosmology Telescope (ACT) + \Planck. These datasets allow us to make the first measurement of this kind at $\sim$arcminute resolution. We find that the radio brightness scales as $F_{\mathrm{radio}} \propto y^{1.5}$ for Abell~401 and $F_{\mathrm{radio}} \propto y^{2.8}$ for Abell~399. Furthermore, using \XMM data, we derive a sublinear correlation between radio and X-ray brightness for both the cluste…
Abell 2744, a massive Hubble Frontier Fields merging galaxy cluster with many multiple images in the core has been the subject of many lens inversions using different methods. While most existing studies compare various inversion methods, we focus on a comparison of reconstructions that use different input lensing data. Since the quantity and quality of lensing data is constantly improving, it makes sense to ask if the estimated uncertainties are robust against changes in the data. We address this question using free-form Grale, which takes only image information as input, and nothing pertaini…
We present results from a deep Chandra observation of Abell 2052. A2052 is a bright, nearby, cooling flow cluster, at a redshift of z=0.035. Concentric surface brightness discontinuities are revealed in the cluster center, and these features are consistent with shocks driven by the AGN, both with Mach numbers of approximately 1.2. The southern cavity in A2052 now appears to be split into two cavities with the southernmost cavity likely representing a ghost bubble from earlier radio activity. There also appears to be a ghost bubble present to the NW of the cluster center. The cycle time measure…
