RELICS: ICL Analysis of the z = 0.566 Merging Cluster WHL J013719.8–08284

We present a pilot study of the intracluster light (ICL) in massive clusters using imaging of the z = 0.566 cluster of galaxies WHL J013719.8–08284 observed by the RELICS project with the Hubble Space Telescope. We measure the ICL fraction in four optical ACS/WFC filters (F435W, F475W, F606W, and F814W) and five infrared WFC3/IR bands (F105W, F110W, F125W, F140W, and F160W). The ICL maps are calculated using the free-of-a-priori-assumptions algorithm CICLE, and the cluster membership is estimated from photometric properties. We find optical ICL fractions that range between ∼6% and 19%, in nice agreement with the values found in previous works for merging clusters. We also observe an ICL fraction excess between 3800 Å and 4800 Å, previously identified as a signature of merging clusters at 0.18 < z < 0.55. This excess suggests the presence of an enhanced population of young/low-metallicity stars in the ICL. All indicators thus point to WHL J013719.8–08284 as a disturbed cluster with a significant amount of recently injected stars, bluer than the average stars hosted by the cluster members and likely stripped out from infalling galaxies during the current merging event. Infrared ICL fractions are ∼50% higher than optical ones, which could be signatures of an older and/or higher-metallicity ICL population that can be associated with the buildup of the brightest cluster galaxy, passive evolution of previously injected young stars, or preprocessing in infalling groups. Finally, investigating the photometry of the cluster members, we tentatively conclude that WHL J013719.8–08284 fulfills the expected conditions for a fossil system progenitor.

Non-Keplerian Orbits in Dark Matter

This paper is concerned with the mathematical description of orbits that do not have a constant central gravitating mass. Instead, the attracting mass is a diffuse condensate, a situation which classical orbital dynamics has never encountered before. The famous Coma Cluster of Galaxies is embedded in Dark Matter. Condensed Neutrino Objects (CNO), which are stable assemblages of neutrinos and anti-neutrinos, are candidates for the Dark Matter. A CNO solution has been attained previously for the Coma Cluster, which allows mathematical modeling of galaxy orbital mechanics within Dark Matter, first reported here. For non-zero eccentricity galaxy orbits, each point along the trajectory sees a different gravitating central mass, akin to satellite orbits inside Earth. Mathematically, the galaxy orbits are non-Keplerian, spirographs.

M87 Supermassive Black Hole Review

M87 is a giant elliptical galaxy in the Virgo cluster of galaxies. The radio source has a core which coincides with the nucleus of the galaxy and a jet of emission which is detected from radio to X-ray bands. A supermassive black hole is assumed to be at the centre of M87 which sends out relativistic particles in the form jets along its axis of rotation. Relativistic particles accelerated in a magnetic field, give out synchrotron radiation. The centre is surrounded by an accretion disc, which is the closest that we can probe into a black hole. High resolution observations are needed to examine the nature of the radio emission closest to the centre of M87. An array of millimetre-band telescopes across the globe were used as an interferometer, called the Event Horizon Telescope, (EHT) to probe the nuclear region. The angular resolution of this interferometer array is 25 microarc sec, at a wavelength of 1.3mm and the data was carefully calibrated and imaged. The resulting image shows an asymmetric ring which is consistent with the predictions of strong gravitational lensing of synchrotron emission from hot plasma near the event horizon. In this paper, we review the results of the observations of the radio galaxy, M87, using the Event Horizon Telescope

An X-ray and Radio Study of the Hubble Frontier Field Cluster Abell S1063

We present results from Chandra X-ray observations and 325 MHz Giant Metrewave Radio Telescope (GMRT) observations of the massive and X-ray luminous cluster of galaxies Abell S1063. We report the detection of large-scale “excess brightness” in the residual Chandra X-ray surface brightness map, which extends at least 2.7 Mpc towards the north-east from the center of the cluster. We also present a high fidelity X-ray flux and temperature map using Chandra archival data of 122 ksec, which shows the disturbed morphology in the cluster. The residual flux map shows the first observational confirmation of the merging axis proposed in earlier simulations. The average temperature within R500 is 11.7 ± 0.56 keV, which makes AS1063 one of the hottest clusters in the nearby Universe. The integrated radio flux density at 325 MHz is found to be 62.0 ± 6.3 mJy. The integrated spectrum of the radio halo follows a power-law with a spectral index α = −1.43 ± 0.13. The radio halo is found to be significantly under-luminous, which favored for both the hadronic as well as the turbulent re-acceleration mechanism for its origin.

Structure and kinematics of the Virgo cluster of galaxies

Aims. This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities VLG < 2600 km s−1 situated within a region of ΔSGL = 30° and ΔSGB = 20° around M 87. About half of the galaxies have distance estimates. Methods. We selected 398 galaxies with distances in a (17 ± 5) Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster. Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extension filament. From a 1D profile of the cluster, we obtain the virial mass estimate of (6.3 ± 0.9)×1014 M⊙, which is in tight agreement with its mass estimate via the external infall pattern of galaxies. Conclusions. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius.