ABSTRACT As part of our program to build a complete radio and X-ray database of all Third Cambridge catalog extragalactic radio sources, we present an analysis of 93 sources for which Chandra ...archival data are available. Most of these sources have already been published. Here we provide a uniform re-analysis and present nuclear X-ray fluxes and X-ray emission associated with radio jet knots and hotspots using both publicly available radio images and new radio images that have been constructed from data available in the Very Large Array archive. For about 1/3 of the sources in the selected sample, a comparison between the Chandra and radio observations was not reported in the literature: we find X-ray detections of 2 new radio jet knots and 17 hotspots. We also report the X-ray detection of extended emission from the intergalactic medium for 15 galaxy clusters.
This paper presents the analysis of Chandra X-ray snapshot observations of a subsample of the extragalactic sources listed in the revised Third Cambridge radio catalog (3CR), previously lacking X-ray ...observations and thus observed during Chandra Cycle 15. This data set extends the current Chandra coverage of the 3CR extragalactic catalog up to redshift z = 1.0. Our sample includes 22 sources consisting of 1 compact steep spectrum source, 3 quasars (QSOs), and 18 FR II radio galaxies. As in our previous analyses, here we report the X-ray detections of radio cores and extended structures (i.e., knots, hotspots, and lobes) for all sources in the selected sample. We measured their X-ray intensities in three energy ranges, soft (0.5-1 keV), medium (1-2 keV), and hard (2-7 keV), and we also performed standard X-ray spectral analysis for brighter nuclei. All radio nuclei in our sample have an X-ray counterpart. We also discovered X-ray emission associated with the eastern knot of 3CR 154, with radio hotspots in 3CR 41, 3CR 54, and 3CR 225B, and with the southern lobe of 3CR 107. Extended X-ray radiation around the nuclei 3CR 293.1 and 3CR 323 on a scale of few tens of kiloparsecs was also found. X-ray extended emission, potentially arising from the hot gas in the intergalactic medium and/or due to the high-energy counterpart of lobes, is detected for 3CR 93, 3CR 154, 3CR 292, and 3CR 323 over a scale of a few hundred kiloparsecs. Finally, this work also presents an update on the state-of-the-art of Chandra and XMM-Newton observations for the entire 3CR sample.
The aim of this paper is to present an analysis of newly acquired X-ray observations of 16 extragalactic radio sources listed in the Third Cambridge Revised (3CR) catalog and not previously observed ...by Chandra. Observations were performed during Chandra Cycle 17, extending X-ray coverage for the 3CR extragalactic catalog up to z = 1.5. Among the 16 targets, two lie at z < 0.5 (3CR 27 at z = 0.184 and 3CR 69 at z = 0.458); all of the remaining 14 have redshifts between 1.0 and 1.5. In the current sample, there are three compact steep spectrum (CSS) sources, three quasars, and an FR I radio galaxy, while the other nine are FR II radio galaxies. All radio sources have an X-ray counterpart. We measured nuclear X-ray fluxes as well as X-ray emission associated with radio jet knots, hotspots, or lobes in three energy bands: soft (0.5-1 keV), medium (1-2 keV), and hard (2-7 keV). We also performed standard X-ray spectral analysis for the four brightest nuclei. We discovered X-ray emission associated with the radio lobe of 3CR 124, a hotspot of the quasar 3CR 220.2, another hotspot of the radio galaxy 3CR 238, and the jet knot of 3CR 297. We also detected extended X-ray emission around the nuclear region of 3CR 124 and 3CR 297 on scales of several tens of kiloparsecs. Finally, we present an update on the X-ray observations performed with Chandra and XMM-Newton on the entire 3CR extragalactic catalog.
We present the analysis of nine radio sources belonging to the Third Cambridge Revised catalog (3CR) observed with Chandra during Cycle 20 in the redshift range between 1.5 and 2.5. This study ...completes the 3CR Chandra Snapshot Survey thus guaranteeing the X-ray coverage of all 3CR sources identified to date. This sample lists two compact steep spectrum sources, four radio galaxies, and three quasars. We detected X-ray emission from all nuclei, with the only exception of 3C 326.1 and 3C 454.1 and from radio lobes in six out of nine sources at a level of confidence larger than ∼5 . We measured X-ray fluxes and luminosities for all nuclei and lobes in the soft (0.5-1 keV), medium (1-2 keV), and hard (2-7 keV) X-ray bands. Since the discovered X-ray extended emission is spatially coincident with the radio structure in all cases, its origin could be due to inverse Compton (IC) scattering of the cosmic microwave background (CMB) occurring in radio lobes.
We present Herschel (PACS and SPIRE) far-infrared (FIR) photometry of a complete sample of z> 1 3CR sources, from the Herschel guaranteed time project The Herschel Legacy of distant radio-loud AGN. ...Combining these with existing Spitzer photometric data, we perform an infrared (IR) spectral energy distribution (SED) analysis of these landmark objects in extragalactic research to study the star formation in the hosts of some of the brightest active galactic nuclei (AGN) known at any epoch. Accounting for the contribution from an AGN-powered warm dust component to the IR SED, about 40% of our objects undergo episodes of prodigious, ULIRG-strength star formation, with rates of hundreds of solar masses per year, coeval with the growth of the central supermassive black hole. Median SEDs imply that the quasar and radio galaxy hosts have similar FIR properties, in agreement with the orientation-based unification for radio-loud AGN. The star-forming properties of the AGN hosts are similar to those of the general population of equally massive non-AGN galaxies at comparable redshifts, thus there is no strong evidence of universal quenching of star formation (negative feedback) within this sample. Massive galaxies at high redshift may be forming stars prodigiously, regardless of whether their supermassive black holes are accreting or not.
Weak emission line quasars are a rare and puzzling group of objects. In this paper, we present one more object of this class found in the Sloan Digital Sky Survey (SDSS). The quasar SDSS ...J094533.99+100950.1, lying at z= 1.66, has practically no C iv emission line, a red continuum very similar to the second steepest of the quasar composite spectra of Richards et al., is not strongly affected by absorption and the Mg ii line, although relatively weak, is strong enough to measure the black hole mass. The Eddington ratio in this object is about 0.45, and the line properties are not consistent with the trends expected at high accretion rates. We propose that the most probable explanation of the line properties in this object, and perhaps in all weak emission line quasars, is that the quasar activity has just started. A disc wind is freshly launched so the low ionization lines which form close to the disc surface are already observed but the wind has not yet reached the regions where high ionization lines or narrow line components are formed. The relatively high occurrence of such a phenomenon may additionally indicate that the quasar active phase consists of several subphases, each starting with a fresh build-up of the broad-line region.
Abstract
We present the analysis of multiwavelength observations of seven extragalactic radio sources, listed as unidentified in the Third Cambridge Revised Catalog (3CR). X-ray observations, ...performed during Chandra Cycle 21, were compared to Very Large Array (VLA), Wide-field Infrared Survey Explorer, and Pan-STARRS observations in the radio, infrared, and optical bands, respectively. All sources in this sample lack a clear optical counterpart, and are thus missing their redshift and optical classification. In order to confirm the X-ray and infrared radio counterparts of core and extended components, here we present for the first time radio maps obtained manually reducing VLA archival data. As in previous papers on the Chandra X-ray snapshot campaign, we report X-ray detections of radio cores and two sources, out of the seven presented here, are found to be members of galaxy clusters. For these two cluster sources (namely, 3CR 409 and 3CR 454.2), we derived surface brightness profiles in four directions. For all seven sources, we measured X-ray intensities of the radio sources and we also performed standard X-ray spectral analysis for the four sources (namely, 3CR 91, 3CR 390, 3CR 409, and 3CR 428) with the brightest nuclei (more than 400 photons in the 2″ nuclear region). We also detected extended X-ray emission around 3CR 390 and extended X-ray emission associated with the northern jet of 3CR 158. This paper represents the first attempt to give a multiwavelength view of the unidentified radio sources listed in the 3CR catalog.
Abstract
We present the analysis of X-ray and optical observations of gas filaments observed in the radio source 3CR 318.1, associated with NGC 5920, the brightest cluster galaxy (BCG) of MKW 3 s, a ...nearby cool core galaxy cluster. This work is one of the first X-ray and optical analyses of filaments in cool core clusters carried out using MUSE observations. We aim at identifying the main excitation processes responsible for the emission arising from these filaments. We complemented the optical VLT/MUSE observations, tracing the colder gas phase, with X-ray Chandra observations of the hotter highly ionized gas phase. Using the MUSE observations, we studied the emission line intensity ratios along the filaments to constrain the physical processes driving the excitation, and, using the Chandra observations, we carried out a spectral analysis of the gas along these filaments. We found a spatial association between the X-ray and optical morphology of these filaments, which are colder and have lower metal abundance than the surrounding intracluster medium (ICM), as already seen in other BCGs. Comparing with previous results from the literature for other BCGs, we propose that the excitation process that is most likely responsible for these filaments emission is a combination of star formation and shocks, with a likely contribution from self-ionizing, cooling ICM. Additionally, we conclude that the filaments most likely originated from AGN-driven outflows in the direction of the radio jet.
We analyze the consequences of the hypothesis that the formation of the Broad Line Region is intrinsically connected to the existence of the cold accretion disk. We assume that the Broad Line Region ...radius is reliably estimated by the formula of Kaspi et al. (CITE, ApJ, 533, 631). We consider three models of the disappearance of the inner disk that limit the existence of the Broad Line Region: (i) the classical ADAF approach, i.e. the inner hot flow develops whenever it can exist; (ii) the disk evaporation model of Meyer & Meyer-Hofmeister (CITE, A&A, 392, L5); (iii) the generalized disk evaporation model of Różańska & Czerny (2000b, A&A, 360, 1170). For each of the models, we determine the minimum value of the Eddington ratio and the maximum value of the broad line widths as functions of the viscosity parameter α and the magnetic field parameter β. We compare the predicted parameter space with observations of several AGN. Weak dependence of the maximum value of the FWHM and minimum value of the Eddington ratio on the black hole mass in our sample is noticeable. It seems to favor the description of the cold disk/hot inner flow transition as in the classical ADAF approach rather than with the model of disk evaporation due to conduction between the disk and accreting corona.
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