HI in proto-cluster environments at z>2: absorbing haloes and the Lya forest

Peer reviewe

The clustering of subp-mJy radio sources in the Bootes Deep Field

Peer reviewe

Magnetic field evolution in giant radio relics using the example of CIZA J2242.8+5301

Article / Letter to editorSterrewach

Magnetic field evolution in giant radio relics using the example of CIZA J2242.8+5301

Large scale structure and cosmolog

Discovery of spectral curvature in the shock downstream region: CIZA J2242.8+5301

Context. Giant cluster radio relics are thought to form at shock fronts in the course of collisions between galaxy clusters. Via processes that are still poorly understood, these shocks accelerate or re-accelerate cosmic-ray electrons and might amplify magnetic fields. The best object to study this phenomenon is the galaxy cluster CIZA J2242.8+5301 as it shows the most undisturbed relic. By means of Giant Metrewave Radio Telescope (GMRT) and Westerbork Synthesis Radio Telescope (WSRT) data at seven frequencies spanning from 153 MHz to 2272 MHz, we study the synchrotron emission in this cluster. Aims: We aim at distinguishing between theoretical injection and acceleration models proposed for the formation of radio relics. We also study the head-tail radio sources to reveal the interplay between the merger and the cluster galaxies. Methods: We produced spectral index, curvature maps, and radio colour-colour plots and compared our data with predictions from models. Results: We present one of the deepest 153 MHz maps of a cluster ever produced, reaching a noise level of 1.5 mJy beam$^{-1}$. We derive integrated spectra for four relics in the cluster, discovering extremely steep spectrum diffuse emission concentrated in multiple patches. We find a possible radio phoenix embedded in the relic to the south of the cluster. The spectral index of the northern relic retains signs of steepening from the front towards the back of the shock also at the radio frequencies below 600 MHz. The spectral curvature in the same relic also increases in the downstream area. The data is consistent with the Komissarov-Gubanov injection models, meaning that the emission we observe is produced by a single burst of spectrally-aged accelerated radio electrons. Appendices are available in electronic form at http://www.aanda.orgImages as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A110GalaxiesLarge scale structure and cosmolog

Confirmation of double peaked Lyα emission at z = 6.593. Witnessing a galaxy directly contributing to the reionisation of the Universe

Large scale structure and cosmolog

LoTSS jellyfish galaxies. III. The first identification of jellyfish galaxies in the Perseus cluster

Galaxie

The Herschel view of the environment of the radio galaxy 4C+41.17 at z = 3.8

We present Herschel observations at 70, 160, 250, 350 and 500 μm of the environment of the radio galaxy 4C+41.17 at z = 3.792. About 65 per cent of the extracted sources are securely identified with mid-infrared sources observed with the Spitzer Space Telescope at 3.6, 4.5, 5.8, 8 and 24 μm. We derive simple photometric redshifts, also including existing 850 and 1200 μm data, using templates of active galactic nuclei, starburst-dominated systems and evolved stellar populations. We find that most of the Herschel sources are foreground to the radio galaxy and therefore do not belong to a structure associated with 4C+41.17. We do, however, find that the spectral energy distribution (SED) of the closest (∼25 arcsec offset) source to the radio galaxy is fully consistent with being at the same redshift as 4C+41.17. We show that finding such a bright source that close to the radio galaxy at the same redshift is a very unlikely event, making the environment of 4C+41.17 a special case. We demonstrate that multiwavelength data, in particular on the Rayleigh–Jeans side of the SED, allow us to confirm or rule out the presence of protocluster candidates that were previously selected by single wavelength data setsPeer reviewe

LoTSS jellyfish galaxies: I. Radio tails in low redshift clusters

Galaxie

An ultradeep multiband VLA survey of the faint radio sky (COSMOS-XS): source catalog and number counts

Galaxie