- ID:
- ivo://CDS.VizieR/J/A+A/657/A25
- Title:
- A521 and Cosmic Snake ALMA abd HST images
- Short Name:
- J/A+A/657/A25
- Date:
- 16 Mar 2022 13:03:06
- Publisher:
- CDS
- Description:
- We study the spatially resolved physical properties of the Cosmic Snake arc in MACS J1206.2-0847 and the arc in Abell 0521 (A521). These are two strongly lensed galaxies at redshifts z=1.036 and z=1.044. We used observations of the Hubble Space Telescope (HST) and the Atacama Large Millimeter/submillimeter Array (ALMA). The former gives access to the star formation rate (SFR) and stellar mass (M*), and the latter to the H_2_ molecular gas mass (Mmol). HST and ALMA observations have similar angular resolutions of 0.15"-0.2", which with the help of strong gravitational lensing enable us to reach spatial resolutions down to ~30pc and ~100pc in these two galaxies, respectively. These resolutions are close to the resolution of observations of nearby galaxies. We study the radial profiles of SFR, M*, and Mmol surface densities of these high-redshift galaxies and compare the corresponding exponential scale lengths with those of local galaxies. We find that the scale lengths in the Cosmic Snake are about 0.5kpc-1.5kpc, and they are 3 to 10 times larger in A521. This is a significant difference knowing that the two galaxies have comparable integrated properties. These high-redshift scale lengths are nevertheless comparable to those of local galaxies, which cover a wide distribution. The particularity of our high-redshift radial profiles is the normalisation of the Mmol surface density profiles (Sigma Mmol), which are offset by up to a factor of 20 with respect to the profiles of z=0 counterparts. The SFR surface density profiles are also offset by the same factor as {SIGMA}Mmol, as expected from the Kennicutt-Schmidt law.
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- ID:
- ivo://CDS.VizieR/J/A+A/647/A3
- Title:
- Abell 3391-Abell 3395 ASKAP/EMU image
- Short Name:
- J/A+A/647/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The pre-merging system of galaxy clusters Abell 3391-Abell 3395 located at a mean redshift of 0.053 has been observed at 1GHz in an ASKAP/EMU Early Science observation as well as in X-rays with eROSITA. The projected separation of the X-ray peaks of the two clusters is ~50{deg} or ~3.1Mpc. Here we present an inventory of interesting radio sources in this field around this cluster merger. While the eROSITA observations provide clear indications of a bridge of thermal gas between the clusters, neither ASKAP nor MWA observations show any diffuse radio emission coinciding with the X-ray bridge. We derive an upper limit on the radio emissivity in the bridge region of <J>_1GHz_<1.2x10^-44^W/H/m3. A non-detection of diffuse radio emission in the X-ray bridge between these two clusters has implications for particle-acceleration mechanisms in cosmological large-scale structure. We also report extended or otherwise noteworthy radio sources in the 30deg^2^ field around Abell 3391-Abell 3395. We identified 20 Giant Radio Galaxies, plus 7 candidates, with linear projected sizes greater than 1Mpc. The sky density of field radio galaxies with largest linear sizes of >0.7Mpc is ~1.7deg^2^, three times higher than previously reported. We find no evidence for a cosmological evolution of the population of Giant Radio Galaxies. Moreover, we find seven candidates for cluster radio relics and radio halos.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A152
- Title:
- Abell 1795 GMRT and Chandra maps
- Short Name:
- J/A+A/618/A152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we analyze AGN activity signatures in the rich nearby galaxy cluster Abell 1795 aiming to confirm and characterize the long-term feedback history in the system. We combine radio observations at 610 and 235MHz from the Giant Metrewave Radio Telescope (GMRT) with 3.4Msec X-ray data from the Chandra Observatory. Extracting radial temperature profiles, as well as Xray and radio surface brightness profiles in three directions showing major morphological disturbances, we highlight the signatures of activity in the system. For the first time we observe radio emission corresponding to the NW X-ray depression, which provides evidence in favor of the classification of the depression as a cavity. We identify two other X-ray cavities situated NW and SW of the AGN. While the central radio emission corresponding to the inner cavities shows a flatter spectral index, the radio extensions associated with the farthest X-ray cavities consist of aged plasma. All observed signatures both in radio and X-ray are consistent with several consecutive episodes of AGN activity, which gave rise to the observed morphology NW and SW from the core. In the southern region, we confirm the cooling wake hypothesis for the origin of the long tail. The deep X-ray data also allows us to distinguish significant distortions in the tail's inner parts, which we attribute to the activity of the AGN.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/1519
- Title:
- Abell 1367 HI sources from AGES
- Short Name:
- J/MNRAS/383/1519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 21cm HI line observations of 5x1deg^2^ centred on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with Sloan Digital Sky Survey (SDSS) optical imaging, we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly, all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large-scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wavelength are also discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A22
- Title:
- Abell 1914 multiwavelength radio images
- Short Name:
- J/A+A/622/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A number of radio observations have revealed the presence of large synchrotron-emitting sources associated with the intra-cluster medium. There is strong observational evidence that the emitting particles have been (re-)accelerated by shocks and turbulence generated during merger events. The particles that are accelerated are thought to have higher initial energies than those in the thermal pool but the origin of such mildly relativistic particles remains uncertain and needs to be further investigated. The galaxy cluster Abell 1914 is a massive galaxy cluster in which X-ray observations show clear evidence of merging activity. We carried out radio observations of this cluster with the LOw Frequency ARay (LOFAR) at 150MHz and the Giant Metrewave Radio Telescope (GMRT) at 610MHz. We also analysed Very Large Array (VLA) 1.4GHz data, archival GMRT 325MHz data, CFHT weak lensing data and Chandra observations. Our analysis shows that the ultra-steep spectrum source (4C38.39; {alpha}<~-2), previously thought to be part of a radio halo, is a distinct source with properties that are consistent with revived fossil plasma sources. Finally, we detect some diffuse emission to the west of the source 4C38.39 that could belong to a radio halo.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A37
- Title:
- Abell 1775 radio images
- Short Name:
- J/A+A/649/A37
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Thermal gas in the center of galaxy clusters can show substantial motions that generate surface brightness and temperature discontinuities known as cold fronts. The motions may be triggered by minor or o-axis mergers that preserve the cool-core of the system. The dynamics of the thermal gas can also generate radio emission from the intra-cluster medium (ICM) and impact the evolution of clusters radio sources. We study the central region of Abell 1775, a system in an ambiguous dynamical state at z=0.072 which is known to host an extended head-tail radio galaxy, with the aim of investigating the connection between thermal and non-thermal components in its center. We made use of a deep (100ks) Chandra observation accompanied by LOFAR 144MHz, GMRT 235MHz and 610MHz, and VLA 1.4GHz radio data. We find a spiral-like pattern in the X-ray surface brightness that is mirrored in the temperature and pseudo-entropy maps. Additionally, we characterize an arc-shaped cold front in the ICM. We interpret these features in the context of a slingshot gas tail scenario. The structure of the head-tail radio galaxy "breaks" at the position of the cold front, showing an extension that is detected only at low frequencies, likely due to its steep and curved spectrum. We speculate that particle re-acceleration is occurring in the outer region of this tail, that in total covers a projected size of 800kpc. We also report the discovery of revived fossil plasma with ultra-steep spectrum radio emission in the cluster core together with a central diffuse radio source that is bounded by the arc-shaped cold front. The results reported in this work demonstrate the interplay between thermal and non-thermal components in the cluster center and the presence of ongoing particle re-acceleration in the ICM on different scales.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A172
- Title:
- Abell 2626 radio source LOFAR image at 144MHz
- Short Name:
- J/A+A/643/A172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new LOFAR data of the galaxy cluster Abell 2626. Weproduced a new, resolved spectral index map of the source with a resolution of 7" and we studied the spatial correlation of radio and X-ray emission to investigate the interplay between thermal and nonthermal plasma. The new LOFAR data changed our view of the Kite because we discovered two steep-spectrum ({alpha}<-1.5) plumes of emission connected to the arcs. On the basis of our results, we propose that the Kite was originally an X-shaped radio galaxy whose fossil radio plasma, after the end of the activity of the central active galactic nucleus, has been compressed as a consequence of motions of the thermal plasma encompassing the galaxy. The interplay between the compression and advection of the fossil plasma, with the restarting of the nuclear activity of the central galaxy,could have enhanced the radio emission of the fossil plasma producing the arcs of the Kite. We also present the first, low-frequency observation of a jellyfish galaxy in the same field, in which we detect extended, low-frequency emission without a counterpart at higher frequencies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4485
- Title:
- Absolute polarimetry observations of 33 pulsars
- Short Name:
- J/MNRAS/453/4485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute polarimetry observations of 33 pulsars were carried out with the Green Bank Telescope in the 1100-1900 MHz band using the Green Bank Ultimate Pulsar Processing Instrument. This group was selected to help complete a larger sample for which accurate proper-motion measurements were available. A combination of profile analysis using the core/double cone model and polarization-angle fitting methods were applied to estimate the "fiducial" longitude of the magnetic axis for each star and refer the linear polarization angle at that point to infinite frequency. As had been found previously, a number of the pulsars are found to have fiducial polarization directions that fall either along or at right angles to their proper-motion directions, whereas upwards of a third of the stars studied show alignments that are neither parallel nor orthogonal.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/7
- Title:
- Abundance of X-shaped radio sources. I. VLA survey
- Short Name:
- J/ApJS/220/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cheung (2007, J/AJ/133/2097) identified a sample of 100 candidate X-shaped radio galaxies using the NRAO FIRST survey; these are small-axial-ratio extended radio sources with off-axis emission. Here, we present radio images of 52 of these sources that have been made from archival Very Large Array data with resolution of about 1". Fifty-one of the 52 were observed at 1.4GHz, 7 were observed at 1.4 and 5GHz, and 1 was observed only at 5GHz. We also present overlays of the Sloan Digital Sky Survey red images for 48 of the sources, and DSS-II overlays for the remainder. Optical counterparts have been identified for most sources, but there remain a few empty fields. Our higher resolution VLA images along with FIRST survey images of the sources in the sample reveal that extended extragalactic radio sources with small axial ratios are largely (60%) cases of double radio sources with twin lobes that have off-axis extensions, usually with inversion-symmetric structure. The available radio images indicate that at most 20% of sources might be genuine X-shaped radio sources that could have formed by a restarting of beams in a new direction following an interruption and axis flip. The remaining 20% are in neither of these categories.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A78
- Title:
- A case study of the HI content of HCG 16
- Short Name:
- J/A+A/632/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hickson Compact Group (HCG) 16 is a prototypical compact group of galaxies in an intermediate stage of the evolutionary sequence proposed by Verdes-Montenegro et al. (2001A&A...377..812V), where its galaxies are losing gas to the intra-group medium (IGrM). The group hosts galaxies that are HI-normal, HI-poor, centrally active with both AGN and starbursts, as well as a likely new member and a 160kpc long HI tidal feature. Despite being a well-studied group at all wavelengths, no previous study of HCG 16 has focused on its extraordinary HI component. The characteristics of HCG 16 make it an ideal case study for exploring which processes are likely to dominate the late stages of evolution in compact groups, and ultimately determine their end states. In order to build a coherent picture of the evolution of this group we make use of the multi-wavelength data available, but focus particularly on HI as a tracer of interactions and evolutionary phase. We reprocess archival VLA L-band observations of HCG 16 using the multi-scale CLEAN algorithm to accurately recover diffuse features. Tidal features and galaxies are separated in 3 dimensions using the SlicerAstro package. The HI deficiency of the separated galaxies is assessed against the benchmark of recent scaling relations of isolated galaxies. This work has been performed with particular attention to reproducibility and is accompanied by a complete workflow to reproduce all the final data products, figures, and results. Despite the clear disruption of the HI component of HCG 16 we find that it is not globally HI deficient, even though HCG 16a and b have lost the majority of their HI and almost 50% of the group's HI is in the IGrM. The HI content of HCG 16d shows highly disturbed kinematics, with only a marginal velocity gradient that is almost perpendicular to its optical major axis. The ~160kpc long tail extending towards the South-East appears to be part of an even larger structure which spatially and kinematically connects NGC 848 to the North-West corner of the group. This study indicates that in the recent past (1Gyr) galaxies HCG 16a and b likely underwent major interactions that unbound gas without triggering significant star formation. This gas was then swept away by a high speed, close encounter with NGC 848. The starburst events HCG 16c and d, likely initiated by their mutual interaction, have triggered galactic winds which, in the case of HCG 16d, appears to have disrupted its HI reservoir. The tidal features still connected to all these galaxies indicate that more HI will soon be lost to the IGrM, while that which remains in the discs will likely be consumed by star formation episodes triggered by their on-going interaction. This is expected to result in a collection of gas-poor galaxies embedded in a diffuse HI structure, which will gradually (over several Gyr) be evaporated by the UV background, resembling the final stage of the evolutionary model of compact groups.
- ID:
- ivo://CDS.VizieR/J/MNRAS/277/1477
- Title:
- A catalogue of BL Lacertae objects
- Short Name:
- J/MNRAS/277/1477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 233 BL Lacertae objects compiled through an extensive bibliographic search updated to mid-1995. A large fraction of the sources listed in the catalogue belongs to well-defined samples and can be used for statistical purposes. A smaller fraction consists of miscellaneous (but confirmed) BL Lacs and of objects classified as BL Lac candidates. We discuss the selection criteria of the different samples, report the discovery of two previously unnoticed BL Lacs in the Palomar-Green survey, and comment on the possible association of some of the still unidentified high galactic latitude gamma-ray (EGRET, see Thompson et al., =1995ApJS..101..259T) sources with BL Lacs. Some statistical properties of the catalogue are also briefly discussed.
- ID:
- ivo://CDS.VizieR/V/138
- Title:
- A catalogue of cross-matched radio/infrared/X-ray sources
- Short Name:
- V/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found. The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic latitudes (|b|>=10deg). At low galactic latitudes (|b|<=10deg) most of unidentified X-ray sources (~94%) lie at |b|>=2deg. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties. These tables are intended as a useful tool for researchers interested in particular identifications.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/5
- Title:
- Accurate OH maser positions from SPLASH. III.
- Short Name:
- J/ApJS/247/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high spatial resolution observations of ground-state OH masers achieved with the Australia Telescope Compact Array (ATCA). These observations targeted 253 pointing centers containing OH maser candidates at all four ground-state OH transitions identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) across 96deg^2^ of the southern Galactic plane (332{deg}<l<334{deg} and -2{deg}<b<+2{deg}, 344{deg}<l<355{deg} and -2{deg}<b<+2{deg}, 358{deg}<l<4{deg} and +2{deg}<b<+6{deg}, 5{deg}<l<10{deg} and -2{deg}<b<+2{deg}). We detect maser emission toward 236 fields and suggest that 7 out of 17 nondetections are due to the slightly lower sensitivity of the ATCA observations, combined with some temporal variability. The superior resolution provided by the ATCA data has allowed us to identify 362 OH maser sites in the 236 target fields. Almost half (160 of 362) of these masers have been detected for the first time. Comparison between these 362 maser sites and information presented in the literature allowed us to categorize 238 sites as evolved star sites (66%), 63 as star formation (17%), 8 as supernova remnants, and 53 as unknown maser sites (15%). We present an analysis of the OH masers across the full SPLASH survey range (176deg^2^) and find that the detection rate of 1.7GHz radio continuum sources (18%) is lower than that previously found at 8.2 and 9.2GHz (38%). We also find that the velocity separations of evolved star sites with symmetric 1612MHz maser profiles are generally smaller than those with asymmetric profiles.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/15
- Title:
- Accurate OH maser positions. II. The GC.
- Short Name:
- J/ApJS/239/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high spatial resolution observations of ground-state OH masers achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted toward 171 pointing centers where OH maser candidates were identified previously in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) toward the Galactic center region between Galactic longitudes of 355* and 5* and Galactic latitudes of -2{deg} and +2{deg}. We detect maser emission toward 162 target fields and suggest that six out of nine nondetections are due to intrinsic variability. Due to the superior spatial resolution of the follow-up ATCA observations, we have identified 356 OH maser sites in the 162 target fields with maser detections. Almost half (161 of 356) of these maser sites have been detected for the first time in these observations. After comparing the positions of these 356 maser sites to the literature, we find that 269 (76%) sites are associated with evolved stars (two of which are PNe), 31 (9%) are associated with star formation, and four are associated with supernova remnants; we were unable to determine the origin of the remaining 52 (15%) sites. Unlike the pilot region, the infrared colors of evolved star sites with symmetric maser profiles in the 1612MHz transition do not show obvious differences compared with those of evolved star sites with asymmetric maser profiles.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/2240
- Title:
- Accurate water maser positions from HOPS
- Short Name:
- J/MNRAS/442/2240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on high spatial resolution water maser observations, using the Australia Telescope Compact Array, towards water maser sites previously identified in the H2O southern Galactic Plane Survey (HOPS) within the area covering Galactic coordinates from l=290 to l=30 and b=-0.5 to b=+0.5. Of the 540 maser sites identified in the single-dish observations of Walsh et al. (2011MNRAS.416.1764W, Cat. J/MNRAS/416/1764), we detect emission in all but 31 fields. These maser sites together comprise 2790 individual spectral features (maser spots), with brightnesses ranging from 0.06Jy to 576Jy and with velocities ranging from -238.5 to +300.5km/s. Based on a definition of maser site size of 4-arcsec (except for G000.667+0.028, also known as Sgr B2, which we treat as a special case), we identify 631 maser sites. We have compared the positions of these sites to the literature to associate the sites with astrophysical objects. We identify 433 (69%) with star formation, 121 (19%) with evolved stars and 77 (12%) as unknown. Comparing the properties of maser sites of different origins, we find that those associated with evolved stars tend to have more maser spots and have smaller angular sizes than those associated with star formation. We present evidence that maser sites associated with evolved stars show an increased likelihood of having a velocity range between 15 and 35 km/s compared to other maser sites. We suggest this is because many of these maser sites are associated with the circumstellar shells of the evolved stars, which are expanding at these velocities. Of the 31 non-detections, we conclude they were not detected due to intrinsic variability and confirm previous results showing that such variable masers tend to be weaker and have simpler spectra with fewer peaks. Of the small number of maser sites showing linear features, we find evidence for lines that are both perpendicular and parallel to known outflows, suggesting that in star formation, H_2_O maser origins may be as varied and as complex as those of class II methanol masers.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A70
- Title:
- Acetaldehyde CH_2_DCOH and CH_3_COD
- Short Name:
- J/A+A/624/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detection of deuterated species may provide information on the evolving chemistry in the earliest phases of star-forming regions. For molecules with two isomeric forms of the same isotopic variant, gas-phase and solid-state formation pathways can be differentiated using their abundance ratio. Spectroscopic databases for astrophysical purposes are built for the two mono deuterated isomeric species CH_2_DCOH and CH_3_COD of the complex organic molecule acetaldehyde. These databases can be used to search and detect these two species in astrophysical surveys, retrieving their column density and therefore abundances. Submillimeter wave and terahertz transitions were measured for mono deuterated acetaldehyde CH2DCOH which is a non-rigid species displaying internal rotation of its asymmetrical CH_2_D methyl group. An analysis of a dataset consisting of previously measured microwave data and the newly measured transition was carried out with a model accounting for the large amplitude torsion. The frequencies of 2556 transitions are reproduced with a unitless standard deviation of 2.3 yielding various spectroscopic constants. Spectroscopic databases for astrophysical purposes were built for CH_2_DCOH using the results of the present analysis and for CH_3_COD using the results of a previous spectroscopic investigation. These two species were both searched for and are detected toward a low-mass star-forming region. We report the first detection of CH2DCOH (93 transitions) and the detection of CH_3_COD (43 transitions) species in source B of the IRAS 16293-2422 young stellar binary system located in the {rho} Ophiuchus cloud region, using the publicly available ALMA Protostellar Interferometric Line Survey.
- ID:
- ivo://CDS.VizieR/J/AJ/140/968
- Title:
- A cluster of compact radio sources in W40
- Short Name:
- J/AJ/140/968
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep 3.6 cm radio continuum observations of the HII region W40 obtained using the Very Large Array (VLA) in its A and B configurations. We detect a total of 20 compact radio sources in a region of 4'x4', with 11 of them concentrated in a band with 30" of extent. We also present JHK photometry of the W40 cluster taken with the QUIRC instrument on the University of Hawaii 2.2m telescope. These data reveal that 15 of the 20 VLA sources have infrared counterparts, and 10 show radio variability with periods less than 20 days. Based on these combined radio and IR data, we propose that eight of the radio sources are candidate ultracompact HII regions, seven are likely to be young stellar objects, and two may be shocked interstellar gas.
- ID:
- ivo://CDS.VizieR/J/ApJS/243/21
- Title:
- A complete sample of broad-line AGN from SDSS-DR7
- Short Name:
- J/ApJS/243/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new, complete sample of 14584 broad-line active galactic nuclei (AGNs) at z<0.35 is presented, which are uncovered homogeneously from the complete database of galaxies and quasars observed spectroscopically in the Sloan Digital Sky Survey Seventh Data Release. The stellar continuum is properly removed for each spectrum with significant host absorption line features, and careful analyses of the emission line spectra, particularly in the H{alpha} and H{beta} wavebands, are carried out. The broad Balmer emission line, particularly H{alpha}, is used to indicate the presence of an AGN. The broad H{alpha} lines have luminosities in a range of 10^38.5^-10^44.3^erg/s, and line widths (FWHMs) of 500-34000km/s. The virial black hole masses, estimated from the broad-line measurements, span a range of 10^5.1^-10^10.3^M_{sun}_, and the Eddington ratios vary from -3.3 to 1.3 in logarithmic scale. Other quantities such as multiwavelength photometric properties and flags denoting peculiar line profiles are also included in this catalog. We describe the construction of this catalog and briefly discuss its properties. The catalog is publicly available online. This homogeneously selected AGN catalog, along with the accurately measured spectral parameters, provides the most updated, largest AGN sample data, which will enable further comprehensive investigations of the properties of the AGN population in the low-redshift universe.
- ID:
- ivo://CDS.VizieR/J/ApJS/160/272
- Title:
- A CO survey of young planetary nebulae
- Short Name:
- J/ApJS/160/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a sensitive survey of young planetary nebulae in the CO J=2-1 line that significantly increases the available data on warm, dense, molecular gas in the early phases of planetary nebula formation. The observations were made using the IRAM 30m telescope with the 3x3 pixel Heterodyne Receiver Array (HERA). The array provides an effective means of discriminating the CO emission of planetary nebulae in the Galactic plane from contaminating emission of interstellar clouds along the line of sight. A total of 110 planetary nebulae were observed in the survey, and 40 were detected. The results increase the number of young planetary nebulae with known CO emission by approximately a factor of 2. The CO spectra yield radial velocities for the detected nebulae, about half of which have uncertain or no velocity measurements at optical wavelengths. The CO profiles range from parabolic to double-peaked, tracing the evolution of structure in the molecular gas. The line widths are significantly larger than on the asymptotic giant branch, and many of the lines show extended wings, which probably result from the effects on the envelopes of high-velocity jets.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A44
- Title:
- ACS J1149.5+2223 LOFAR and VLA images
- Short Name:
- J/A+A/650/A44
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Radio halos and relics are Mpc-scale diffuse radio sources in galaxy clusters, which have a steep spectral index {alpha}>1 (defined as S{prop.to}{nu}^-{alpha}^). It has been proposed that halos and relics arise from particle acceleration induced by turbulence and weak shocks that are injected into the intracluster medium (ICM) during mergers. MACS J1149.5+2223 is a high-redshift (z=0.544) galaxy cluster possibly hosting a radio halo and a relic. We analysed LOw Frequency Array (LOFAR), Giant Metrewave Radio Telescope, and Karl G. Jansky Very Large Array (JVLA) radio data at 144, 323, and 1500MHz, respectively. In addition, we analysed archival Chandra X-ray data to characterise the thermal and non-thermal properties of the cluster. We obtained radio images at different frequencies to investigate the spectral properties of the radio halo. We used Chandra X-ray images to constrain the thermal properties of the cluster and to search for discontinuities (due to cold fronts or shock fronts) in the surface brightness of the ICM. By combining radio and X-ray images, we carried out a point-to-point analysis to study the connection between the thermal and non-thermal emission. We measured a steep spectrum of the halo, which can be described by a power-law with {alpha}=1.49+/-0.12 between 144 and 1500MHz. The radio surface brightness distribution across the halo is found to correlate with the X-ray brightness of the ICM. The derived correlation shows a sub-linear slope in the range 0.4-0.6. We also report two possible cold fronts in north-east and north-west, but deeper X-ray observations are required to firmly constrain the properties of the upstream emission. We show that the combination of high-redshift, steep radio spectrum, and sub-linear radio-X scaling of the halo rules out hadronic models. An old (~1Gyr ago) major merger likely induced the formation of the halo through stochastic re-acceleration of relativistic electrons. We suggest that the two possible X-ray discontinuities may be part of the same cold front. In this case, the coolest gas pushed towards the north-west might be associated with the cool core of a sub-cluster involved in the major merger. The peculiar orientation of the south-east relic might indicate a different nature of this source and requires further investigation.