- ID:
- ivo://CDS.VizieR/J/ApJ/769/107
- Title:
- RVs and [Fe/H] of star members of NGC 6388
- Short Name:
- J/ApJ/769/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By combining high spatial resolution and wide-field spectroscopy performed, respectively, with SINFONI and FLAMES at the ESO/VLT we measured the radial velocities of more than 600 stars in the direction of NGC 6388, a Galactic globular cluster which is suspected to host an intermediate-mass black hole. Approximately 55% of the observed targets turned out to be cluster members. The cluster velocity dispersion has been derived from the radial velocity of individual stars: 52 measurements in the innermost 2", and 276 stars located between 18" and 600". The velocity dispersion profile shows a central value of ~13km/s, a flat behavior out to ~60" and a decreasing trend outward. The comparison with spherical and isotropic models shows that the observed density and velocity dispersion profiles are inconsistent with the presence of a central black hole more massive than ~2000M_{sun}_. These findings are at odds with recent results obtained from integrated light spectra, showing a velocity dispersion profile with a steep central cusp of 23-25km/s at r<2" and suggesting the presence of a black hole with a mass of ~1.7x10^4^M_{sun}_. We also found some evidence of systemic rotation with amplitude A_rot_~8km/s in the innermost 2" (0.13pc), decreasing to A_rot_=3.2km/s at 18"<r<160".
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/572/A42
- Title:
- SagDIG carbon and oxygen stars
- Short Name:
- J/A+A/572/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sagittarius dwarf irregular (also known as SagDIG or UKS 1927-177) is a gas-rich, low-metallicity and star-forming galaxy, at the outskirts (D~1.1Mpc) of the Local Group. Projected relatively close to the Galactic center [(l,b)=(21.06,-16.29)] the resolved stellar populations of this galaxy reflects a strong Galactic foreground contamination, attributed to the thin and thick disk and the halo. This has so far hampered the reconstruction of its star formation and chemical enrichment history, and studies of individual stars. We have analyzed two ACS@HST data-sets (GO-9820 and GO-10472) that were collected in August 2003 and June 2005, having a ~1.85 years epoch separation. The data has allowed the derivation of the relative proper-motion for the SagDIG stellar population and reduction of the heavy foreground contamination. This provides a much clearer view of the red stellar populations (young RSG and intermediate-age AGB as well as the old RGB and AGB). The ACS/WFC data was collected in the F475W, F606W and F814W HST filters, and the published table provides a photometric calibration of the ACS/WFC filters that follows Bedin et al. (2003AJ....126..247B). This is based on the Vega spectrum and follows the recipes given by Holtzmann et al. (1995PASP..107..156H) for WFPC2, using the most updated in-flight characterization of the camera (Sirianni et al. 2005PASP..117.1049S). Besides the reported magnitudes and their relative errors, we also provide the pixel-based offset between the two F814W epochs, which is used to separate the SagDIG stellar population from the Galactic foreground (see Sec.3 of the paper for details).
- ID:
- ivo://CDS.VizieR/J/ApJ/635/243
- Title:
- Sample of GOODS/CDFS early-type galaxies
- Short Name:
- J/ApJ/635/243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the evolution of field early-type galaxies in a sample extracted from the ACS images of the southern GOODS field. The galaxies are selected by means of a nonparametric analysis, followed by visual inspection of the candidates with a concentrated surface brightness distribution. We furthermore exclude from the final sample those galaxies that are not consistent with an evolution into the Kormendy relation between surface brightness and size that is observed for z=0 ellipticals. The final set, which comprises 249 galaxies with a median redshift z_m_=0.71, represents a sample of early-type systems not selected with respect to color, with similar scaling relations as those of bona fide elliptical galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/170
- Title:
- Sample SNRs for M31 and M33
- Short Name:
- J/ApJ/795/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Hubble Space Telescope photometry to measure star formation histories, we age-date the stellar populations surrounding supernova remnants (SNRs) in M31 and M33. We then apply stellar evolution models to the ages to infer the corresponding masses for their supernova progenitor stars. We analyze 33 M33 SNR progenitors and 29 M31 SNR progenitors in this work. We then combine these measurements with 53 previously published M31 SNR progenitor measurements to bring our total number of progenitor mass estimates to 115. To quantify the mass distributions, we fit power laws of the form dN/dM{prop.to}M^-{alpha}^. Our new larger sample of M31 progenitors follows a distribution with {alpha}=4.4_-0.4_^+0.4^, and the M33 sample follows a distribution with {alpha}=3.8_-0.5_^+0.4^. Thus both samples are consistent within the uncertainties, and the full sample across both galaxies gives {alpha}=4.2_-0.3_^+0.3^. Both the individual and full distributions display a paucity of massive stars when compared to a Salpeter initial mass function, which we would expect to observe if all massive stars exploded as SN that leave behind observable SNR. If we instead fix {alpha}=2.35 and treat the maximum mass as a free parameter, we find M_max_~35-45 M_{sun}_, indicative of a potential maximum cutoff mass for SN production. Our results suggest that either SNR surveys are biased against finding objects in the youngest (<10 Myr old) regions, or the highest mass stars do not produce SNe.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/69
- Title:
- SEDs of galaxies at 3.8<z<5 in GOODS
- Short Name:
- J/ApJ/738/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present evidence for strong H{alpha} emission in galaxies with spectroscopic redshifts in the range of 3.8<z<5.0 over the Great Observatories Origins Deep Survey fields. Among 74 galaxies detected in the Spitzer IRAC 3.6 and 4.5um bands, more than 70% of the galaxies show clear excess at 3.6um compared to the expected flux density from stellar continuum only. We provide evidence that this 3.6um excess is due to H{alpha} emission redshifted into the 3.6um band, and classify these 3.6um excess galaxies to be H{alpha} emitter (HAE) candidates. The selection of HAE candidates using an excess in broadband filters is sensitive to objects whose rest-frame H{alpha} equivalent width (EW) is larger than 350{AA}. The H{alpha} inferred star formation rates (SFRs) of the HAEs range between 20 and 500M_{sun}_/yr and are a factor of ~6 larger than SFRs inferred from the UV continuum. The ratio between the H{alpha} luminosity and UV luminosity of HAEs is also on average larger than that of local starbursts.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/7
- Title:
- SG1120-1202 members HST imaging & 24um fluxes
- Short Name:
- J/ApJ/836/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Hubble Space Telescope to obtain WFC3/F390W imaging of the supergroup SG1120-1202 at z=0.37, mapping the UV emission of 138 spectroscopically confirmed members. We measure total (F390W-F814W) colors and visually classify the UV morphology of individual galaxies as "clumpy" or "smooth." Approximately 30% of the members have pockets of UV emission (clumpy) and we identify for the first time in the group environment galaxies with UV morphologies similar to the "jellyfish" galaxies observed in massive clusters. We stack the clumpy UV members and measure a shallow internal color gradient, which indicates that unobscured star formation is occurring throughout these galaxies. We also stack the four galaxy groups and measure a strong trend of decreasing UV emission with decreasing projected group distance (R_proj_). We find that the strong correlation between decreasing UV emission and increasing stellar mass can fully account for the observed trend in (F390W-F814W)-R_proj_, i.e., mass-quenching is the dominant mechanism for extinguishing UV emission in group galaxies. Our extensive multi-wavelength analysis of SG1120-1202 indicates that stellar mass is the primary predictor of UV emission, but that the increasing fraction of massive (red/smooth) galaxies at R_proj_<~2R_200_ and existence of jellyfish candidates is due to the group environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/851/48
- Title:
- SLACS. XIII. Galaxy-scale strong lens candidates
- Short Name:
- J/ApJ/851/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the full sample of 118 galaxy-scale strong-lens candidates in the Sloan Lens ACS (SLACS) Survey for the Masses (S4TM) Survey, which are spectroscopically selected from the final data release of the Sloan Digital Sky Survey. Follow-up Hubble Space Telescope (HST) imaging observations confirm that 40 candidates are definite strong lenses with multiple lensed images. The foreground-lens galaxies are found to be early-type galaxies (ETGs) at redshifts 0.06-0.44, and background sources are emission-line galaxies at redshifts 0.22-1.29. As an extension of the SLACS Survey, the S4TM Survey is the first attempt to preferentially search for strong-lens systems with relatively lower lens masses than those in the pre-existing strong-lens samples. By fitting HST data with a singular isothermal ellipsoid model, we find that the total projected mass within the Einstein radius of the S4TM strong-lens sample ranges from 3x10^10^M_{sun}_ to 2x10^11^M_{sun}_. In Shu+ (2015ApJ...803...71S), we have derived the total stellar mass of the S4TM lenses to be 5x10^10^M_{sun}_ to 1x10^12^M_{sun}_. Both the total enclosed mass and stellar mass of the S4TM lenses are on average almost a factor of 2 smaller than those of the SLACS lenses, which also represent the typical mass scales of the current strong-lens samples. The extended mass coverage provided by the S4TM sample can enable a direct test, with the aid of strong lensing, for transitions in scaling relations, kinematic properties, mass structure, and dark-matter content trends of ETGs at intermediate-mass scales as noted in previous studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/777/97
- Title:
- SL2S galaxy-scale lens sample. III.
- Short Name:
- J/ApJ/777/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope (HST) imaging data and Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey (SL2S) project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies (ETGs). Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods, we estimate that our Einstein radii are accurate to ~3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with space-based images. Information from the lens models is used together with spectroscopic information from companion Paper IV (2013ApJ...777...98S) to classify the systems, resulting in a final sample of 39 confirmed (grade A) lenses and 17 promising candidates (grade B,C).
- ID:
- ivo://CDS.VizieR/J/ApJ/884/L31
- Title:
- Spectra & HST obs. of gal. in 1ES1553+113 field
- Short Name:
- J/ApJ/884/L31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of ultraviolet (UV)+X-ray spectra for surveys of the circumgalactic/intergalactic medium (CGM/IGM). Nicastro+ (2018Natur.558..406N) reported the detection of two OVII WHIM absorbers at z=0.4339 and 0.3551 in its spectrum, suggesting that the WHIM is metal rich and sufficient to close the missing baryons problem. Our survey indicates that the blazar is a member of a z=0.433 group and that the higher-z OVII candidate arises from its intragroup medium. The resulting bias precludes its use in baryon censuses. The z=0.3551 candidate occurs in an isolated environment 630kpc from the nearest galaxy (with stellar mass logM_*_/M_{sun}_~9.7), which we show is unexpected for the WHIM. Finally, we characterize the galactic environments of broad HI Ly{alpha} absorbers (Doppler widths of b=40-80km/s; T<~4x10^5^K) that provide metallicity-independent WHIM probes. On average, broad Ly{alpha} absorbers are ~2x closer to the nearest luminous (L>0.25L*) galaxy (700kpc) than narrow (b<30km/s; T<~4x10^5^K) ones (1300kpc) but ~2x further than OVI absorbers (350kpc). These observations suggest that gravitational collapse heats portions of the IGM to form the WHIM, but with feedback that does not enrich the IGM far beyond galaxy/group halos to levels currently observable in UV/X-ray metal lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/157
- Title:
- Spectrophotometric redshifts of GOODS galaxies
- Short Name:
- J/ApJ/883/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the accuracy of 4000{AA}/Balmer-break based redshifts by combining Hubble Space Telescope (HST) grism data with photometry. The grism spectra are from the Probing Evolution And Reionization Spectroscopically survey with HST using the G800L grism on the Advanced Camera for Surveys. The photometric data come from a compilation by the 3D-HST collaboration of imaging from multiple surveys (notably, the Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS) and 3D-HST). We show evidence that spectrophotometric redshifts (SPZs) typically improve the accuracy of photometric redshifts by ~17%-60%. Our SPZ method is a template-fitting-based routine that accounts for correlated data between neighboring points within grism spectra via the covariance matrix formalism and also accounts for galaxy morphology along the dispersion direction. We show that the robustness of the SPZ is directly related to the fidelity of the D4000 measurement. We also estimate the accuracy of continuum-based redshifts, i.e., for galaxies that do not contain strong emission lines, based on the grism data alone ({sigma}_{Delta}z/(1+z)_^NMAD^<~0.06). Given that future space-based observatories like Wide Field InfraRed Survey Telescope and Euclid will spend a significant fraction of time on slitless spectroscopic observations, we estimate number densities for objects with |{Delta}z/(1+z_s_)|<=0.02. We predict ~700-4400 galaxies degree^-2^ for galaxies with D4000>1.1 and |{Delta}z/(1+z_s_)|<=0.02 to a limiting depth of i_AB_=24mag. This is especially important in the absence of an accompanying rich photometric data set like the existing one for the CANDELS fields, where redshift accuracy from future surveys will rely only on the presence of a feature like the 4000{AA}/Balmer breaks or the presence of emission lines within the grism spectra.
