A5044608406- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Magnetic confinement fusion research
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Computational Physics and Python Applications
- Classical Antiquity Studies
- Optical properties and cooling technologies in crystalline materials
- Dark Matter and Cosmic Phenomena
- Historical, Religious, and Philosophical Studies
- Distributed and Parallel Computing Systems
- Space Science and Extraterrestrial Life
- History and Developments in Astronomy
- Particle Detector Development and Performance
- Space exploration and regulation
- Advanced Database Systems and Queries
Stanford University
2016-2019
Kavli Institute for Particle Astrophysics and Cosmology
2016-2019
Center for Astrophysics Harvard & Smithsonian
2015-2016
Universität Hamburg
2013-2015
Hamburger Fern-Hochschule
2013-2014
Constructor University
2010-2013
We present deep LOFAR observations between 120-181 MHz of the "Toothbrush" (RX J0603.3+4214), a cluster that contains one brightest radio relic sources known. Our exploit new and novel calibration scheme to probe 10 times deeper than any previous study in this relatively unexplored part spectrum. The observations, when combined with VLA, GMRT, Chandra X-ray data, provide information about nature merger shocks their role re-accelerating relativistic particles. derive spectral index $\alpha =...
ABSTRACT LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of low-frequency sky. At same time also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images challenging due presence direction-dependent calibration errors, caused by imperfect knowledge station beam shapes ionosphere. Furthermore, large data volume clock errors...
The cluster 1RXS J0603.3+4214 is a merging galaxy that hosts three radio relics and giant halo. northern relic, the Toothbrush, 1.9 Mpc long has an unusual linear morphology. According to simple diffusive shock acceleration theory, its spectral index indicates Mach number of 3.3–4.6. Here, we present results from deep XMM–Newton observation cluster. We observe two distinct cores have survived merger. presence shocks at or near locations confirmed by density temperature discontinuities....
The aim of this work is to probe the magnetic field properties in relics and infall regions galaxy clusters using Faraday Rotation Measures. We present Very Large Array multi-frequency observations seven sources region South-West Coma cluster, where infalling group NGC4839 relic 1253+275 are located. Measure maps for observed derived analysed study Coma. discuss how interpret data by comparing mock rotation measures that produced simulating different 3-dimensional models. model gives best...
Giant radio halos are Mpc-size sources found in some merging galaxy clusters. The synchrotron emitting electrons thought to be (re)accelerated by plasma turbulence induced the of two massive Cool core clusters have a low temperature core, likely an indication that major merger has not recently occurred. CL1821+643 is one strongest cool known so far. Surprisingly, we detect giant halo with largest linear size $\sim$ 1.1 Mpc. We discuss and X-ray properties cluster framework proposed models...
We present VIMOS-VLT spectroscopy of the Frontier Fields cluster MACS~J0416.1-2403 (z=0.397). Taken as part CLASH-VLT survey, large spectroscopic campaign provided more than 4000 reliable redshifts, including ~800 member galaxies. The unprecedented sample members at this redshift allows us to perform a highly detailed dynamical and structural analysis out ~2.2$r_{200}$ (~4Mpc). Our substructures reveals complex system composed main massive ($M_{200}$~0.9$\times 10^{15} M_{\odot}$) presenting...
We studied the intracluster medium of galaxy cluster CIZA J2242.8+5301 using deep XMM-Newton observations. The hosts a remarkable 2-Mpc long, ~50-kpc wide radio relic that has been nicknamed "Sausage". A smaller, more irregular counter-relic is also present, along with faint giant halo. analysed distribution ICM physical properties, and searched for shocks by trying to identify density temperature discontinuities. East southern relic, we find evidence shock compression corresponding Mach...
CIZA J2242.8+5301, a merging galaxy cluster at z=0.19, hosts double-relic system and faint radio halo. Radio observations frequencies ranging from few MHz to several GHz have shown that the spectral index outer edge of N relic corresponds shock Mach number 4.6+/-1.1, under assumptions diffusive acceleration thermal particles in test particle regime. Here, we present results new Chandra cluster. The surface brightness profile across only hints discontinuity (<2-sigma detection). Nevertheless,...
Abstract To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA Chandra observations of HST Frontier Fields cluster MACS J0717.5+3745 . The image shows a complex event, with at least four belonging to different merging subclusters. Northwest cluster, ∼0.7 Mpc from center, there is ram-pressure-stripped core that appears have traversed densest parts after entering intracluster medium (ICM) direction filament southeast. We...
Abstract Golovich et al. present an optical imaging and spectroscopic survey of 29 radio relic merging galaxy clusters. In this paper, we study to identify substructure quantify the dynamics mergers. Using a combined photometric approach, minimum number substructures in each system describe populations estimate line-of-sight velocity difference between likely subclusters. We find that components mergers are typically small compared with maximum 3D relative (usually <1000 km s −1 often...
The Coma cluster is one of the nearest galaxy clusters, and first in which a radio halo peripheral relic were discovered. While its central parts intracluster medium have been studied extensively, X-ray observations plasma near scarce. Here, we present results from re-analysis 22-ks archival XMM-Newton observation. Across relic, detect shock Mach number about 2. This excludes previously suggested hypothesis that was formed by turbulence. Furthermore, multiwavelenth numerical models do not...
Pairs of radio relics are believed to form during cluster mergers, and best observed when the merger occurs in plane sky. Mergers can also produce halos, through complex processes likely linked turbulent re-acceleration cosmic-ray electrons. However, only some clusters with double show a halo. Here, we present novel method derive upper limits on halo emission, analyse archival X-ray Chandra data, as well galaxy velocity dispersions lensing order understand key parameter that switches...
Context. We present the results from Suzaku observations of merging cluster galaxies CIZA J2242.8+5301 at z = 0.192.
Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold X-ray substructure, radio halos, offsets between dark matter (DM) gas components. Using observations from Chandra, Jansky Very Large Array, Giant Metrewave Radio Telescope, Hubble Space we present a multiwavelength analysis of merging Frontier Fields MACS J0416.1-2403 (z = 0.396), which consists NE SW subclusters whose cores are separated sky by ∼250 kpc....
ABSTRACT We present an analysis of the merging cluster MACS J1149.5+2223 using archival imaging from Subaru/Suprime-Cam and multi-object spectroscopy Keck/DEIMOS Gemini/GMOS. employ two- three-dimensional substructure tests determine that is composed two separate mergers among three subclusters occurring ∼1 Gyr apart. The primary merger gives rise to elongated X-ray morphology a radio relic in southeast. brightest galaxy member northern subcluster merger. This very massive ( <?CDATA...
Extended steep-spectrum radio emission in a galaxy cluster is usually associated with recent merger. However, given the complex scenario of mergers, many discovered sources hardly fit into strict boundaries precise taxonomy. This especially true for phoenixes that do not have very well defined observational criteria. Radio are aged lobes whose reactivated by compression or other mechanisms. Here, we present detection phoenix close to moment its formation. The source located Abell 1033,...
The galaxy cluster ZwCl 2341.1+0000 is a merging system at z = 0.27, which hosts two radio relics and central, faint, filamentary structure. have unusually flat integrated spectral indices of −0.49 ± 0.18 −0.76 0.17, values that cannot be easily reconciled with the theory standard diffusive shock acceleration thermal particles weak merger shocks. We present imaging results from XMM–Newton Chandra observations cluster, aimed to detect characterize density discontinuities in intracluster...
The HST Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist four dark matter halos. We present results from deep (365 ks) Chandra observations cluster, which reveal distant cold front (z=0.544) discovered date. In outskirts, we also detect hints a surface brightness edge that could be bow shock preceding front. substructure analysis identified several components with large relative radial velocities, thus indicating at least some...
We present multi-wavelength observations of the centre RXCJ1504.1-0248 - galaxy cluster with most luminous and relatively nearby cool core at z~0.2. Although there are several galaxies within 100 kpc core, only brightest (BCG), which lies peak X-ray emission, has blue colours strong line-emission. Approximately 80 Msun/yr intracluster gas is cooling below emitting temperatures, similar to observed UV star formation rate ~140 Msun/yr. Most occurs in BCG a 42 long filament continuum, line that...
We report on high-resolution JVLA and Chandra observations of the HST Frontier Cluster MACS J0717.5+3745. J0717.5+3745 offers largest contiguous magnified area any known cluster, making it a promising target to search for lensed radio X-ray sources. With 1.0-6.5 GHz imaging in A B configuration, we detect total 51 compact sources within covered by imaging. Within this sample find 7 with amplification factors larger than $2$. None these are identified as multiply-lensed. Based luminosities,...
We use XMM-Newton observations of the galaxy cluster MaxBCG J217.95869+13.53470 to analyze its physical properties and dynamical state. is found at a redshift 0.16, has mass ~1x10^14 Msun, luminosity 7.9x10^43 erg/s. The temperature map shows presence hot regions towards north west brightest (BCG). From entropy distribution, high match location regions; more are west, ~165 kpc southwest central AGN. A second X-ray bright visible ~90 northeast BCG, 0.162. This likely be BCG smaller, infalling...
Multiwavelength studies of radio relics at merger shocks set powerful constraints on the origin and formation mechanism. However, for X-ray observations, a main difficulty is represented by low surface brightness far out in cluster outskirts, where are typically found. Here, we present XMM-Newton results from 130-ks observation CIZA J2242.8+5301, z=0.19 that hosts double relic. We focus well-defined northern There difference ~55% between temperature measure behind relic, measured with...
Abstract LOFAR, the Low Frequency Radio Array, is a new pan‐European radio telescope that almost fully operational. One of its main drivers to make deep images low frequency sky. To be able do this number challenges need addressed. These include high data rates, removal interference, calibration beams and correcting for corrupting influence ionosphere. key science goals study merger shocks, particle acceleration mechanisms structure magnetic fields in nearby distant merging clusters. Recent...