- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3461
- Title:
- 6.7-GHz methanol masers-dust associations
- Short Name:
- J/MNRAS/446/3461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of 870{mu}m continuum observations, using the Large APEX Bolometer Camera, towards 77 class-II, 6.7-GHz methanol masers identified by the Methanol MultiBeam (MMB) survey to map the thermal emission from cool dust towards these objects. These data complement a study of 630 methanol masers associated with compact dense clumps identified from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. Compact dust emission is detected towards 70 sources, which implies a dust-association rate of 99 per cent for the full MMB catalogue. Evaluation of the derived dust and maser properties leads us to conclude that the combined sample represents a single population tracing the same phenomenon. We find median clump masses of a few 10^3^M_{sun}_ and that all but a handful of sources satisfy the mass-size criterion required for massive star formation. This study provides the strongest evidence of the almost ubiquitous association of methanol masers with massive, star-forming clumps. The fraction of methanol-maser associated clumps is a factor of ~2 lower in the outer Galaxy than the inner Galaxy, possibly a result of the lower metallicity environment of the former. We find no difference in the clump-mass and maser-luminosity distributions of the inner and outer Galaxy. The maser-pumping and clump formation mechanisms are therefore likely to be relatively invariant to Galactic location. Finally, we use the ratio of maser luminosity and clump mass to investigate the hypothesis that the maser luminosity is a good indicator of the evolutionary stage of the embedded source, however, we find no evidence to support this.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/851
- Title:
- Giant Radio Quasars properties
- Short Name:
- J/MNRAS/426/851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analysed the optical and radio properties of lobe-dominated giant-sized (>0.72Mpc) radio quasars and compared the results with those derived for a sample of smaller radio sources to determine whether the large size of some extragalactic radio sources is related to the properties of their nuclei. We compiled the largest (to date) sample of giant radio quasars, including 24 new and 21 previously known objects, and calculated a number of important parameters of their nuclei such as the black hole mass and the accretion rate.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/254
- Title:
- GLASS. IX. Structural param. from HFF & GLASS
- Short Name:
- J/ApJ/835/254
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using deep Hubble Frontier Fields imaging and slitless spectroscopy from the Grism Survey from Space, we study 2200 cluster and 1748 field galaxies at 0.2<=z<=0.7 to determine the impact of environment on galaxy size and structure at stellar masses logM_*_/M_{sun}_>7.8, an unprecedented limit at these redshifts. Based on simple assumptions-r_e_=f(M_*_)-we find no significant differences in half-light radii (r_e_) between equal-mass cluster or field systems. More complex analyses --r_e_=f(M_*_,U-V,n,z,{Sigma})-- reveal local density ({Sigma}) to induce only a 7%+/-3% (95% confidence) reduction in r_e_ beyond what can be accounted for by U-V color, Sersic index (n), and redshift (z) effects. Almost any size difference between galaxies in high- and low-density regions is thus attributable to their different distributions in properties other than environment. Indeed, we find a clear color-r_e_ correlation in low-mass passive cluster galaxies (logM_*_/M_{sun}_<9.8) such that bluer systems have larger radii, with the bluest having sizes consistent with equal-mass star-forming galaxies. We take this as evidence that large-r_e_ low-mass passive cluster galaxies are recently acquired systems that have been environmentally quenched without significant structural transformation (e.g., by ram pressure stripping or starvation). Conversely, ~20% of small-r_e_ low-mass passive cluster galaxies appear to have been in place since z>~3. Given the consistency of the small-r_e_ galaxies' stellar surface densities (and even colors) with those of systems more than ten times as massive, our findings suggest that clusters mark places where galaxy evolution is accelerated for an ancient base population spanning most masses, with late-time additions quenched by environment-specific mechanisms mainly restricted to the lowest masses.
- ID:
- ivo://CDS.VizieR/VIII/102
- Title:
- GLEAM II. Galactic plane
- Short Name:
- VIII/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work makes available a further of the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey, covering half of the accessible galactic plane, across 20 frequency bands sampling 72-231MHz, with resolution 4-2arcmin. Unlike previous GLEAM data releases, we used multi-scale CLEAN to better deconvolve large-scale galactic structure. For the galactic longitude ranges 345{deg}<l<67{deg}, 180{deg}<l<240{deg}, we provide a compact source catalogue of 22037 components selected from a 60-MHz bandwidth image centred at 200MHz, with RMS noise ~-10-20mJy/beam and position accuracy better than 2-arcsec. The catalogue has a completeness of 50% at ~120mJy, and a reliability of 99.86%. It covers galactic latitudes 1{deg}<=|b|<=10{deg} towards the galactic centre and |b|<=10{deg} for other regions, and is available from Vizier; images covering |b|<=10{deg} for all longitudes are made available on the GLEAM Virtual Observatory (VO).server and SkyView.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/1075
- Title:
- Globular cluster in nearby dwarf galaxies. II
- Short Name:
- J/MNRAS/396/1075
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare nuclear globular clusters (nGCs) in dwarf galaxies and Galactic GCs with extended (hot) horizontal branches (EHB-GCs) in order to test the suggested external origin of the latter and the conditions at which GC self-enrichment can operate. Using luminosities and structural parameters of nGCs in low-mass (mainly late-type) dwarf galaxies from Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) imaging, we derive the present-day escape velocities (Vesc) of stellar ejecta to reach the cluster tidal radius and compare them with those of EHB-GCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/L27
- Title:
- Globular clusters in ACSVCS early-type galaxies
- Short Name:
- J/ApJ/773/L27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a determination of the two-dimensional shape parameters of the blue and red globular cluster systems (GCSs) in a large number of elliptical galaxies and lenticular galaxies (early-type galaxies, called ETGs). We use a homogeneous data set of the globular clusters in 23 ETGs obtained from the HST/ACS Virgo Cluster Survey. The position angles of both blue and red GCSs show a correlation with those of the stellar light distribution, showing that the major axes of the GCSs are well aligned with those of their host galaxies. However, the shapes of the red GCSs show a tight correlation with the stellar light distribution as well as with the rotation property of their host galaxies, while the shapes of the blue GCSs do much less. These provide clear geometric evidence that the origins of the blue and red globular clusters are distinct and that ETGs may have dual halos: a blue (metal-poor) halo and a red (metal-rich) halo. These two halos show significant differences in metallicity, structure, and kinematics, indicating that they are formed in two distinguishable ways. The red halos might have formed via dissipational processes with rotation, while the blue halos are through accretion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/L55
- Title:
- Globular clusters in M31 from K-band photometry
- Short Name:
- J/MNRAS/392/L55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the relationship between low-mass X-ray binaries (LMXBs) and globular clusters (GCs) using United Kingdom Infrared Telescope (UKIRT) observations of M31 and existing Chandra, XMM-Newton and ROSAT catalogues. By fitting King models to these data, we have estimated the structural parameters and stellar collision rates of 239 of its GCs. We show a highly significant trend between the presence of a LMXB and the stellar collision rate of a cluster. The stellar collision rate is found to be a stronger predictor of which clusters will host LMXBs than the host cluster mass. We argue that our results show that the stellar collision rate of the clusters is the fundamental parameter related to the production LMXBs. This is consistent with the formation of LMXBs through dynamical interactions with little direct dependence on the neutron star retention fraction or cluster mass.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/879
- Title:
- Globular clusters in nearby dwarf galaxies
- Short Name:
- J/MNRAS/392/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the old globular cluster (GC) population of 68 faint (M_V_>−16mag) dwarf galaxies located in the halo regions of nearby (<~12Mpc) loose galaxy groups and in the field environment based on archival Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) images in F606W and F814W filters.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/87
- Title:
- Globular clusters of M60 with HST
- Short Name:
- J/ApJ/760/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present g and z photometry and size estimates for globular clusters (GCs) in the massive Virgo elliptical NGC 4649 (M60) using a five-pointing Hubble Space Telescope/Advanced Camera for Surveys mosaic. The metal-poor GCs show a monotonic negative metallicity gradient of -0.43+/-0.10dex per dex in radius over the full radial range of the data, out to ~24kpc. There is evidence for substantial color substructure among the metal-rich GCs. The metal-poor GCs have typical sizes ~0.4pc larger than the metal-rich GCs out to large galactocentric distances (>~20kpc), favoring an intrinsic explanation for the size difference rather than projection effects. There is no clear relation between half-light radius and galactocentric distance beyond ~15kpc, suggesting that the sizes of GCs are not generically set by tidal limitation. Finally, we identify ~20 candidate ultracompact dwarfs that extend down to surprisingly faint absolute magnitudes (M_z_~-8.5), and may bridge the gap between this class and "extended clusters" in the Local Group. Three of the brighter candidates have published radial velocities and can be confirmed as bona fide ultracompact dwarfs; follow-up spectroscopy will determine the nature of the remainder of the candidates.
260. Globulars of M81
- ID:
- ivo://CDS.VizieR/J/AJ/109/1055
- Title:
- Globulars of M81
- Short Name:
- J/AJ/109/1055
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained photometric BVR, morphological, and astrometric information on 3774 objects located within a 25' radius of M81. This catalogue is complete for 15 <= V <= 21; it is used here to identify globular cluster candidates in M81 and as a database for a statistical analysis of the system as a whole. The M81 globular cluster system is revealed as a strong surface density excess of ~70 objects within an 11 kpc galactocentric radius. The total population is estimated at N_T = 210 +/- 30 globulars. The spatial, (B-V), and (V-R) distributions are very similar to those of the Milky Way and of M31. Small but significant systematic errors in Madore et al.'s [AJ, 106, 2243 (1993)] photometry could be responsible for an overestimate of the Cepheid distance to M81 [(m-M)0 = 27.8] and we propose a revised modulus of (m-M)0 = 27.5 +/- 0.3. The globular cluster luminosity function then reaches its maximum at M_V* = -7.5 +/- 0.4, as it does in the galaxy and in M31. There is suggestive evidence that 13 +/- 5 objects are globulars seen through the disk of M81; spectroscopy or high-resolution imaging will resolve this issue. Using the (B-R)0 index to trace [Fe/H], we notice a weak dependence of mean metallicity on galactocentric distance, as observed in the galaxy and in M31. This result argues in favour of in situ globular formation during the continuous collapse and self-enrichment of an early-type spiral host.
