The parsec-scale properties of the radio galaxy 4C 26.42 in the dense cooling core cluster A1795

The aim of the present work is to study the radio emission on the parsec scale of 4C 26.42, the Brightest cluster galaxy in Abell 1795, in the framework of radiosources in a dense cool core cluster. We present Very Long Baseline Array (VLBA) observations at 1.6, 5, 8.4 and 22 GHz. We performed a spectral index and multiepoch analysis. The source appears two-sided with a well defined and symmetric Z-structure at ~5 mas from the core. The kiloparsec-scale morphology is similar to the parsec-scale structure, but reversed in P.A., with symmetric 90 deg. bends at about 2 arcsec from the nuclear region. Comparing data obtained at 3 different epochs we derive a 3$\sigma$ limit to the apparent proper motion of $\beta_a$ < 0.04. We suggest that the parsec-scale jets are sub-relativistic, in contrast with the high velocities found for most low-power radio galaxies. The origin of the unusual radio morphology remains a puzzle. We suggest that the identification of the parent galaxy with the central cD in a cooling cluster plays an important role in the properties and structure of the jets.Comment: 8 pages, 4 figures, 4 tables, Accepted for pubblication in Astronomy & Astrophysic

First simultaneous optical/near-infrared imaging of an X-ray selected, high-redshift cluster of galaxies with GROND: the galaxy population of XMMU J0338.7+0030 at z=1.1

The XMM-Newton Distant Cluster Project is a serendipitous survey for clusters of galaxies at redshifts z>=0.8 based on deep archival XMM-Newton observations. ... Low-significance candidate high-z clusters are followed up with the seven-channel imager GROND (Gamma-Ray Burst Optical and Near-Infrared Detector) that is mounted at a 2m-class telescope. ... The test case is XMMU J0338.7+0030, suggested to be at z~1.45+/-0.15 from the analysis of the z-H vs H colour-magnitude diagram obtained from the follow-up imaging. Later VLT-FORS2 spectroscopy enabled us to identify four members, which set this cluster at z=1.097+/-0.002. To reach a better knowledge of its galaxy population, we observed XMMU J0338.7+0030 with GROND for about 6 hr. The publicly available photo-z code le Phare was used. The Ks-band number counts of the non-stellar sources out of the 832 detected down to z'~26 AB-mag in the 3.9x4.3 square arcmin region of XMMU J0338.7+0030 imaged at all GROND bands clearly exceed those computed in deep fields/survey areas at ~20.5 - 22.5 AB-mag. The photo-z's of the three imaged spectroscopic members yield z=1.12+/-0.09. The spatial distribution and the properties of the GROND sources with a photo-z in the range 1.01 - 1.23 confirm the correspondence of the X-ray source with a galaxy over-density at a significance of at least 4.3 sigma. Candidate members that are spectro-photometrically classified as elliptical galaxies define a red locus in the i'-z' vs z' colour-magnitude diagram that is consistent with the red sequence of the cluster RDCS J0910+5422 at z=1.106. XMMU J0338.7+0030 hosts also a population of bluer late-type spirals and irregulars. The starbursts among the photometric members populate both loci, consistently with previous results. The analysis of the available data set indicates that XMMU J0338.7+0030 is a low-mass cluster (M_200 ~ 1E14 M_sun) at z=1.1. (Abridged)Comment: accepted for publication in Astronomy & Astrophysics Main Journal, 27 pages, 24 figures, 1 tabl

Heating groups and clusters of galaxies: the role of AGN jets

X-Ray observations of groups and clusters of galaxies show that the Intra-Cluster Medium (ICM) in their cores is hotter than expected from cosmological numerical simulations of cluster formation which include star formation, radiative cooling and SN feedback. We investigate the effect of the injection of supersonic AGN jets into the ICM using axisymmetric hydrodynamical numerical simulations. A simple model for the ICM, describing the radial properties of gas and the gravitational potential in cosmological N-Body+SPH simulations of one cluster and three groups of galaxies at redshift z=0, is obtained and used to set the environment in which the jets are injected. We varied the kinetic power of the jet and the emission-weighted X-Ray temperature of the ICM. The jets transfer their energy to the ICM mainly by the effects of their terminal shocks. A high fraction of the injected energy can be deposited through irreversible processes in the cluster gas, up to 75% in our simulations. We show how one single, powerful jet can reconcile the predicted X-Ray properties of small groups, e.g. the Lx-Tx relation, with observations. We argue that the interaction between AGN jets and galaxy groups and cluster atmospheres is a viable feedback mechanism.Comment: 18 pages, 14 figures, to appear on Astronomy and Astrophysic

The THESEUS space mission concept: science case, design and expected performances

THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5¿1 arcmin localization, an energy band extending from several MeV down to 0.3¿keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7¿m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ¿20s/early ¿30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).© 2018 COSPARS.E. acknowledges the financial support from contracts ASI-INAF 1/009/10/0, NARO15 ASI-INAF 1/037/12/0 and ASI 2015-046-R.0. R.H. acknowledges GACR grant 13-33324S. S.V. research leading to these results has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 606176. D.S. was supported by the Czech grant 1601116S GA CR. Maria Giovanna Dainotti acknowledges funding from the European Union through the Marie Curie Action FP7-PEOPLE-2013-IOF, under grant agreement No. 626267 (>Cosmological Candles>)

The THESEUS space mission concept : science case, design and expected performances

Abstract THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5-1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift ∼ 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ’20s / early ’30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).Peer reviewe

CoreValve implantation for severe aortic regurgitation: a multicentre registry.

AIMS: We sought to evaluate the outcome of transcatheter aortic valve replacement (TAVR) with the CoreValve Revalving System (CRS-TAVR) in inoperable patients presenting with severe aortic regurgitation (AR), compared to in patients treated for severe native aortic stenosis (AS). From October 2008 to January 2013, 1,557 consecutive patients undergoing CRS-TAVR, of whom 26 (1.6%) presented with AR, were prospectively followed. Compared with patients with AS, patients with AR were significantly younger (mean age 73±10 vs. 82±6, p=0.02), more frequently in NYHA Class III/IV (95% vs. 73%, p=0.01) and had a higher incidence of severe pulmonary hypertension (sPAP >60 mmHg, 31% vs. 10%, p=0.007). Log EuroSCORE and STS score were similar. VARC-2-defined device success was lower in the AR group (79% vs. 96%, p=0.006). At one month, patients treated for AR had a higher overall mortality (23% vs. 5.9%; OR 4.22 [3.03-8.28], p<0.001) and cardiac mortality (15.3% vs. 4%, OR 4.01 [2.40-7.66], p<0.001). Results were consistent at 12 months: overall mortality (31% vs. 19%, HR 2.1 [1.5-4.41], p<0.001) and cardiac mortality (19.2% vs. 6%, HR 3.1 [2.09-8.22], p<0.001). CRS-TAVR for AR is associated with a significantly higher mortality compared to CRS-TAVR for AS. Considering the ominous prognosis of these patients when treated medically, TAVR may be a reasonable choice in selected patients. In this regard, conventional risk scores have an inadequate predictive value

CoreValve implantation for severe aortic regurgitation: a multicentre registry

We sought to evaluate the outcome of transcatheter aortic valve replacement (TAVR) with the CoreValve Revalving System (CRS-TAVR) in inoperable patients presenting with severe aortic regurgitation (AR), compared to in patients treated for severe native aortic stenosis (AS). From October 2008 to January 2013, 1,557 consecutive patients undergoing CRS-TAVR, of whom 26 (1.6%) presented with AR, were prospectively followed. Compared with patients with AS, patients with AR were significantly younger (mean age 73±10 vs. 82±6, p=0.02), more frequently in NYHA Class III/IV (95% vs. 73%, p=0.01) and had a higher incidence of severe pulmonary hypertension (sPAP >60 mmHg, 31% vs. 10%, p=0.007). Log EuroSCORE and STS score were similar. VARC-2-defined device success was lower in the AR group (79% vs. 96%, p=0.006). At one month, patients treated for AR had a higher overall mortality (23% vs. 5.9%; OR 4.22 [3.03-8.28], p<0.001) and cardiac mortality (15.3% vs. 4%, OR 4.01 [2.40-7.66], p<0.001). Results were consistent at 12 months: overall mortality (31% vs. 19%, HR 2.1 [1.5-4.41], p<0.001) and cardiac mortality (19.2% vs. 6%, HR 3.1 [2.09-8.22], p<0.001). CRS-TAVR for AR is associated with a significantly higher mortality compared to CRS-TAVR for AS. Considering the ominous prognosis of these patients when treated medically, TAVR may be a reasonable choice in selected patients. In this regard, conventional risk scores have an inadequate predictive value

Transcatheter aortic valve implantation under angiographic guidance with and without adjunctive transesophageal echocardiography

Although transcatheter aortic valve implantation (TAVI) is still currently guided by transesophageal echocardiography (TEE) in a considerable number of hospitals, exclusive angiographic (Angio) guidance seems a reasonable approach in this setting. To date, however, no studies have directly compared the outcomes of TAVI according to the imaging modality used for procedural guidance. We, therefore, used data from a large multicenter data repository to compare the outcomes of TAVI guided exclusively by Angio and ATEE. All consecutive patients with severe aortic stenosis who underwent TAVI with the CoreValve Revalving System (CRS) in 9 Italian centers from September 2007 to March 2014, dichotomized according to the imaging support used to guide the procedure (ATEE and Angio), were included. Thirty-day and 12-month clinical outcomes were evaluated. Propensity matching analysis was performed to adjust for baseline differences. A total of 625 patients were included (256 and 369 patients were included in the ATEE and Angio groups, respectively). Patients from the ATEE more frequently underwent TAVI under general anesthesia compared with Angio group (37.9% vs 22.8%, respectively, p <0.001). Importantly, ∼80% of the patients experienced mild or even less aortic regurgitation as assessed by angiography after the procedure, without between-group differences. Postdilation and valve-in-valve rates were equivalent (24.7% vs 25%, p = 0.934 and 5.5% vs 3.4%, respectively, p = 0.217). No differences were revealed in the rates of death, cardiovascular death, and stroke or transient ischemic attack at 12-month follow-up. These results were sustained after propensity matching analysis. In conclusion, as long as a comprehensive procedural planning is performed, TAVI with CRS may be performed exclusively under angiographic guidance without the need for associated TEE