- ID:
- ivo://CDS.VizieR/J/ApJ/788/48
- Title:
- X-ray through NIR photometry of NGC 2617
- Short Name:
- J/ApJ/788/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After the All-Sky Automated Survey for SuperNovae discovered a significant brightening of the inner region of NGC 2617, we began a ~70 day photometric and spectroscopic monitoring campaign from the X-ray through near-infrared (NIR) wavelengths. We report that NGC 2617 went through a dramatic outburst, during which its X-ray flux increased by over an order of magnitude followed by an increase of its optical/ultraviolet (UV) continuum flux by almost an order of magnitude. NGC 2617, classified as a Seyfert 1.8 galaxy in 2003, is now a Seyfert 1 due to the appearance of broad optical emission lines and a continuum blue bump. Such "changing look active galactic nuclei (AGNs)" are rare and provide us with important insights about AGN physics. Based on the H{beta} line width and the radius-luminosity relation, we estimate the mass of central black hole (BH) to be (4+/-1)x10^7^ M_{sun}_. When we cross-correlate the light curves, we find that the disk emission lags the X-rays, with the lag becoming longer as we move from the UV (2-3 days) to the NIR (6-9 days). Also, the NIR is more heavily temporally smoothed than the UV. This can largely be explained by a simple model of a thermally emitting thin disk around a BH of the estimated mass that is illuminated by the observed, variable X-ray fluxes.
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- ID:
- ivo://CDS.VizieR/J/ApJS/245/17
- Title:
- X-shaped radio galaxies from FIRST
- Short Name:
- J/ApJS/245/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 290 "winged" or X-shaped radio galaxies (XRGs) extracted from the latest (2014 December 17) data release of the "Very Large Array Faint Images of the Radio Sky at Twenty centimeter". We have combined these radio images with their counterparts in the TIFR GMRT sky survey at 150MHz, in an attempt to identify any low surface brightness radio emission present in these sources. This has enabled us to assemble a sample of 106 "strong" XRG candidates and 184 "probable" XRG candidates whose XRG designation needs to be verified by further observations. The present sample of 290 XRG candidates is almost twice as large as the number of XRGs currently known. Twenty-five of our 290 XRG candidates (9 "strong" and 16 "probable") are identified as quasars. Double-peaked narrow emission lines are seen in the optical spectra of three of the XRG candidates (two "strong" and one "probable"). Nearly 90% of the sample is located in the FR II domain of the Owen-Ledlow diagram. A few of the strong XRG candidates have a rather flat radio spectrum (spectral index {alpha} flatter than -0.3) between 150MHz and 1.4GHz, or between 1.4 and 5GHz. Since this is not expected for lobe-dominated extragalactic radio sources (like nearly all known XRGs), these sources are particularly suited for follow-up radio imaging and near-simultaneous measurement of the radio spectrum.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/48
- Title:
- "X-shaped" radio sources. II. Sample properties
- Short Name:
- J/ApJ/852/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an earlier paper, we presented Jansky Very Large Array multi-frequency, multi-array continuum imaging of a unique sample of low-axial ratio radio galaxies. In this paper, the second in the series, we examine the images to learn the phenomenology of how the off-axis emission relates to the main radio source. Inversion-symmetric offset emission appears to be bimodal and to originate from one of two strategic locations: outer ends of radio lobes (outer-deviation) or from inner ends (inner-deviation). The latter sources are almost always associated with edge-brightened sources. With S- and Z-shaped sources being a subset of outer-deviation sources, this class lends itself naturally to explanations involving black hole axis precession. Our data allow us to present a plausible model for the more enigmatic inner-deviation sources with impressive wings; as for outer-deviation sources these too require black hole axis shifts, although they also require plasma backflows into relic channels. Evolution in morphology over time relates the variety in structures in inner-deviation sources including XRGs. With features such as non- collinearities, central inner-S "spine," corresponding lobe emission peaks, double and protruding hotspots not uncommon, black hole axis precession, drifts, or flips could be active in a significant fraction of radio sources with prominent off-axis emission. At least 4% of radio galaxies appear to undergo black hole axis rotation. Quasars offer a key signature for recognizing rotating axes. With a rich haul of sources that have likely undergone axis rotation, our work shows the usefulness of low-axial ratio sources in pursuing searches for binary supermassive black holes.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A1
- Title:
- X-shooter spectra of 6 ~2.2 quasars
- Short Name:
- J/A+A/603/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the spectra of six z~2.2 quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and X-shooter's spectral coverage allow us to cover the rest spectral range ~1200-7000{AA} for the simultaneous detection of optical and ultraviolet lines emitted by the Broad Line Region. Simultaneous measurements, avoiding issues related to quasars variability, help us understanding the connection between different Broad Line Region line profiles generally used as virial estimators of Black Holes masses in quasars. The goal of this work is comparing the emission lines from the same object to check on the reliability of H{alpha}, MgII and CIV with respect to H{beta}. H{alpha} and MgII linewidths correlate well with H{beta}, while CIV shows a poorer correlation, due to the presence of strong blueshifts and asymmetries in the profile. We compare our sample with the only other two whose spectra were taken with the same instrument and for all examined lines our results are in agreement with the ones obtained with X-shooter at z~1.5-1.7. We finally evaluate CIII] as a possible substitute of CIV in the same spectral range and find that its behaviour is more coherent with those of the other lines: we believe that, when a high quality spectrum such as the ones we present is available and a proper modelization with the FeII and FeIII emissions is performed, the use of this line is more appropriate than that of CIV if not corrected for the contamination by non-virialized components.
1015. XXL Survey. DR2
- ID:
- ivo://CDS.VizieR/IX/52
- Title:
- XXL Survey. DR2
- Short Name:
- IX/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second data release (DR2) of the XXL Survey, contextually with the appearance of a second A&A special issue dedicated to XXL. This intermediate release includes the following catalogues and data: The X-ray point source catalogue (3XLSS) and the associated multiwavelength catalogues in the XXL-N and XXL-s areas (XXL paper XXVII). The same paper also provides the list of XMM pointings used, and a supplementary catalogue of redshifts obtained with the AAOmega spectrograph in the XXL-S area. The XXL-365-GC galaxy cluster catalogue (XXL paper XX) with the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. The ATCA 2.1 GHz radio source catalogue in the XXL-S area (XXL paper XXVIII), together with the catalogue of ther optical and near infrared counterparts (XXL paper XXVI). The GMRT 610 MHz radio source catalogue in the XXL-N area (XXL paper XXIX). FITS images of the XXL-North field: continuum radio mosaic from observations with the Giant Meterwave Radio Telescope (GMRT) at 610MHz, and the corresponding noise map. A complete spectrophotometric sample of galaxies within X-ray detected, optically spectroscopically confirmed groups and clusters (G&C), including also field objects, in the XXL-N area (XXL paper XXII). The list of brightest cluster galaxies (BCGs) in the XXL-N area (XXL paper XXVIII). FITS images of the two radio galaxies described in XXL paper XXXIV. ATCA XXL-S source classification data (XXL paper XXXVI) http://sci.esa.int/xmm-newton/60686-tracing-the-universe-x-ray-survey-\ supports-standard-cosmological-model/ List of XXL DR2 papers: XVI. The clustering of X-ray selected galaxy clusters at z~0.3 XVII. X-ray and Sunyaev-Zel'dovich properties of the redshift 2.0 galaxy cluster XLSSC 122 XVIII. ATCA 2.1 GHz radio source catalogue and source counts for the XXL-South field XIX. A realistic population of simulated X-ray AGN: Comparison of models with observations XX. The 365 cluster catalogue XXI. The environment and clustering of X-ray AGN in the XXL-South field XXII. The XXL-North spectrophotometric sample and galaxy stellar mass function in X-ray detected groups and clusters XXIII. The mass scale of XXL clusters from ensemble spectroscopy XXIV. The final detection pipeline XXV. Cosmological analysis of the C1 cluster number counts XXVI. Optical and near infrared identification of the ATCA 2.1 GHz radio sources in the XXL-S field XXVII. The 3XLSS point source catalogue XXVIII. Galaxy luminosity functions of the XXL-N clusters XXIX. GMRT 610 MHz continuum observations XXX. Characterisation of the XLSSsC N01 supercluster and analysis of the galaxy stellar populations XXXI. Classification and host galaxy properties of 2.1 GHz ATCA XXL-S radio sources XXXII. Spatial clustering of the XXL-S AGN XXXIII. Chandra constraints on the AGN contamination of z > 1 XXL galaxy clusters XXXIV. Double irony in XXL-North. A tale of two radio galaxies in a supercluster at z = 0.14 XXXV. The role of cluster mass in AGN activity XXXVI. Evolution and black hole feedback of high-excitation and low-excitation radio galaxies in XXL-S
- ID:
- ivo://CDS.VizieR/J/A+AS/139/393
- Title:
- Young Massive Star Clusters. II.
- Short Name:
- J/A+AS/139/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 4 lists photometric data for Young Massive Star Clusters identified in a sample of 21 nearby galaxies. The photometric data have been corrected for Galactic foreground extinction. Each cluster is identified by the abbreviated NGC number of its host galaxy and an object number: nxxx-yyy is object number yyy in the galaxy NGC xxx. Effective cluster radii have been obtained by modeling the cluster images as MOFFAT15 functions convolved with the point-spread function measured on the CCD images.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/78
- Title:
- z=4.5 and z=5.7 LAEs properties with Spitzer
- Short Name:
- J/ApJ/813/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a stellar population modeling analysis of a sample of 162 z=4.5 and 14 z=5.7 Ly{alpha} emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 {mu}m from the Spitzer Ly{alpha} Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 {mu}m for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >=3{sigma} in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8^-10^11^ M_{sun}_. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr^-1^ Gyr, while the remainder have ages <100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8-20x10^8^ M_{sun}_) and young (64-570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-based star formation rate (SFR) similar to that at lower redshifts, in that higher mass galaxies exhibit higher SFRs. However, the z=4.5 LAE correlation is elevated 4-5 times in SFR compared to continuum-selected galaxies at similar redshifts. The exception is the most massive LAEs which have SFRs similar to galaxies at lower redshifts suggesting that they may represent a different population of galaxies than the traditional lower-mass LAEs, perhaps with a different mechanism promoting Ly{alpha} photon escape.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/44
- Title:
- 120 3<=z<=5 galaxies candidates in CANDELS fields
- Short Name:
- J/ApJ/897/44
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Using the CANDELS photometric catalogs for the Hubble Space Telescope ACS and WFC3, we identified massive evolved galaxies at 3<z<4.5 employing three different selection methods. We find the comoving number density of these objects to be ~2x10^-5^ and 8x10^-6^/Mpc^3^ after correction for completeness for two redshift bins centered at z=3.4, 4.7. We quantify a measure of how much confidence we should have for each candidate galaxy from different selections and what the conservative error estimates propagated into our selection are. Then we compare the evolution of the corresponding number densities and their stellar mass density with numerical simulations, semianalytical models, and previous observational estimates, which shows slight tension at higher redshifts as the models tend to underestimate the number and mass densities. By estimating the average halo masses of the candidates (M_h_~4.2, 1.9, and 1.3x1012M{sun} for redshift bins centered at z=3.4, 4.1, and 4.7), we find them to be consistent with halos that were efficient in turning baryons to stars, relatively immune to the feedback effects, and on the verge of transition into hot-mode accretion. This can suggest the relative cosmological starvation of the cold gas followed by an overconsumption phase in which the galaxy rapidly consumes the available cold gas as one of the possible drivers for the quenching of the massive evolved population at high redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/32
- Title:
- Zwicky Transient Facility BTS. I.
- Short Name:
- J/ApJ/895/32
- Date:
- 16 Mar 2022 00:25:08
- Publisher:
- CDS
- Description:
- The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (~3{pi}) with newly found transient candidates announced via public alerts. The ZTF Bright Transient Survey (BTS) is a large spectroscopic campaign to complement the photometric survey. BTS endeavors to spectroscopically classify all extragalactic transients with m_peak_<~18.5mag in either the g_ZTF_ or r_ZTF_ filters, and publicly announce said classifications. BTS discoveries are predominantly supernovae (SNe), making this the largest flux-limited SN survey to date. Here we present a catalog of 761 SNe, classified during the first nine months of ZTF (2018 April 1-2018 December 31). We report BTS SN redshifts from SN template matching and spectroscopic host-galaxy redshifts when available. We analyze the redshift completeness of local galaxy catalogs, the redshift completeness fraction (RCF; the ratio of SN host galaxies with known spectroscopic redshift prior to SN discovery to the total number of SN hosts). Of the 512 host galaxies with SNe Ia, 227 had previously known spectroscopic redshifts, yielding an RCF estimate of 44%{+/-}4%. The RCF decreases with increasing distance and decreasing galaxy luminosity (for z<0.05, or ~200Mpc, RCF~0.6). Prospects for dramatically increasing the RCF are limited to new multifiber spectroscopic instruments or wide-field narrowband surveys. Existing galaxy redshift catalogs are only ~50% complete at r~16.9mag. Pushing this limit several magnitudes deeper will pay huge dividends when searching for electromagnetic counterparts to gravitational wave events or sources of ultra-high-energy cosmic rays or neutrinos.