- 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.
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Search Results
- 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/835/123
- Title:
- Globular clusters in NGC 474 from CFHT obs.
- Short Name:
- J/ApJ/835/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters (GCs) are some of the most visible tracers of the merging and accretion histories of galaxy halos. Metal-poor GCs, in particular, are thought to arrive in massive galaxies largely through dry, minor merging events, but it is rare to see a direct connection between GCs and visible stellar streams. NGC 474 is a post-merger early-type galaxy with dramatic fine structures made of concentric shells and radial streams that have been more clearly revealed by deep imaging. We present a study of GCs in NGC 474 to better establish the relationship between merger-induced fine structure and the GC system. We find that many GCs are superimposed on visible streams and shells, and about 35% of GCs outside 3R_e,galaxy_ are located in regions of fine structure. The spatial correlation between GCs and fine structure is significant at the 99.9% level, which shows that this correlation is not coincidental. The colors of GCs on fine structures are mostly blue, and we also find an intermediate-color population that is dominant in the central region and that will likely passively evolve to have colors consistent with a traditional metal-rich GC population. The association of the blue GCs with fine structures is direct confirmation that many metal-poor GCs are accreted onto massive galaxy halos through merging events and that the progenitors of these mergers are sub-L^*^ galaxies.
- 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.
1365. 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/199
- Title:
- Globulars with X-ray sources in NGC 5128
- Short Name:
- J/ApJ/682/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We detect 353 X-ray point sources, mostly low-mass X-ray binaries (LMXBs), in four Chandra observations of Centaurus A (NGC 5128), the nearest giant early-type galaxy, and correlate this point-source population with the largest available ensemble of confirmed and likely globular clusters (GCs) associated with this galaxy. Of the X-ray sources, 31 are coincident with 30 GCs that are confirmed members of the galaxy by radial velocity measurement (two X-ray sources match one GC within our search radius), while one X-ray source coincides with a GC resolved by Hubble Space Telescope (HST) images. Another 36 X-ray point sources match probable, but spectroscopically unconfirmed, GC candidates.
1367. GMASS photometry
- ID:
- ivo://CDS.VizieR/J/A+A/549/A63
- Title:
- GMASS photometry
- Short Name:
- J/A+A/549/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We designed a spectroscopic observing campaign of a sample of both massive, quiescent and star-forming galaxies at z>1.4, called Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS). To determine redshifts and physical properties, such as metallicity, dust content, dynamical masses, and star formation history, we performed ultra-deep spectroscopy with the red-sensitive optical spectrograph FORS2 at the VLT. Our sample consists of objects, within the CDFS/GOODS area, detected at 4.5 micron, to be sensitive to stellar mass rather than star formation intensity. The spectroscopic targets were selected with a photometric redshift constraint (z>1.4) and magnitude constraints (B(AB)<26, I(AB)<26.5), which should ensure that these are faint, distant, and fairly massive galaxies. Up to 30 hours of spectroscopy of 174 spectroscopic targets and 70 additional objects enabled us to determine 210 redshifts, of which 145 are at z>1.4. We publicly release the redshifts and reduced spectra.
- ID:
- ivo://CDS.VizieR/J/ApJS/191/254
- Title:
- GMBCG galaxy cluster catalog from SDSS DR7
- Short Name:
- J/ApJS/191/254
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large catalog of optically selected galaxy clusters from the application of a new Gaussian Mixture Brightest Cluster Galaxy (GMBCG) algorithm to SDSS Data Release 7 data. The algorithm detects clusters by identifying the red-sequence plus brightest cluster galaxy (BCG) feature, which is unique for galaxy clusters and does not exist among field galaxies. Red-sequence clustering in color space is detected using an Error Corrected Gaussian Mixture Model. We run GMBCG on 8240 deg^2^ of photometric data from SDSS DR7 to assemble the largest ever optical galaxy cluster catalog, consisting of over 55,000 rich clusters across the redshift range from 0.1<z<0.55. We present Monte Carlo tests of completeness and purity and perform cross-matching with X-ray clusters and with the maxBCG sample at low redshift. These tests indicate high completeness and purity across the full redshift range for clusters with 15 or more members.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A110
- Title:
- GMOS-IFU spectroscopy of dwarf galaxy HS 2236+1344
- Short Name:
- J/A+A/569/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main goal of this study is to carry out a spatially resolved investigation of the warm interstellar medium (ISM) in the extremely metal-poor blue compact dwarf galaxy HS 2236+1344. Special emphasis is laid on the analysis of the spatial distribution of chemical abundances, emission-line ratios and kinematics of the ISM, and to the recent star-forming activity in this galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/83
- Title:
- GMOS spectroscopic obs. of SNR candidates in M83
- Short Name:
- J/ApJ/839/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a spectrophotometric study sampling the 300 candidate supernova remnants (SNRs) in M83 identified through optical imaging with Magellan/IMACS and Hubble Space Telescope/WFC3. Of the 118 candidates identified based on a high [SII]{lambda}{lambda}6716,6731 to H{alpha} emission ratio, 117 show spectroscopic signatures of shock-heated gas, confirming them as SNRs-the largest uniform set of SNR spectra for any galaxy. Spectra of 22 objects with a high [OIII]{lambda}5007 to H{alpha} emission ratio, selected in an attempt to identify young ejecta-dominated SNRs like Cas A, reveal only one (previously reported) object with the broad (1000km/s) emission lines characteristic of ejecta-dominated SNRs, beyond the known SN1957D remnant. The other 20 [OIII]-selected candidates include planetary nebulae, compact HII regions, and one background QSO. Although our spectroscopic sample includes 22 SNRs smaller than 11pc, none of the other objects show broad emission lines; instead their spectra stem from relatively slow (~200km/s) radiative shocks propagating into the metal-rich interstellar medium of M83. With six SNe in the past century, one might expect more of M83's small-diameter SNRs to show evidence of ejecta; this appears not to be the case. We attribute their absence to several factors, including that SNRs expanding into a dense medium evolve quickly to the ISM-dominated phase, and that SNRs expanding into regions already evacuated by earlier SNe are probably very faint.