- ID:
- ivo://CDS.VizieR/J/ApJS/240/33
- Title:
- MaDCoWS. I. Catalog of z~1 galaxy clusters
- Short Name:
- J/ApJS/240/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Massive and Distant Clusters of WISE Survey (MaDCoWS), a search for galaxy clusters at 0.7<=z<=1.5 based upon data from the Wide-field Infrared Survey Explorer (WISE) mission. MaDCoWS is the first cluster survey capable of discovering massive clusters at these redshifts over the full extragalactic sky. The search is divided into two regions-the region of the extragalactic sky covered by Pan-STARRS ({delta}{>}-30{deg}) and the remainder of the southern extragalactic sky at {delta}{<}-30{deg} for which shallower optical data from the SuperCOSMOS Sky Survey is available. In this paper, we describe the search algorithm, characterize the sample, and present the first MaDCoWS data release-catalogs of the 2433 highest amplitude detections in the WISE-Pan-STARRS region and the 250 highest amplitude detections in the WISE-SuperCOSMOS region. A total of 1723 of the detections from the WISE-Pan-STARRS sample have also been observed with the Spitzer Space Telescope, providing photometric redshifts and richnesses, and an additional 64 detections within the WISE-SuperCOSMOS region also have photometric redshifts and richnesses. Spectroscopic redshifts for 38 MaDCoWS clusters with IRAC photometry demonstrate that the photometric redshifts have an uncertainty of {sigma}z/(1+z)~0.036. Combining the richness measurements with Sunyaev-Zel'dovich observations of MaDCoWS clusters, we also present a preliminary mass-richness relation that can be used to infer the approximate mass distribution of the full sample. The estimated median mass for the WISE-Pan-STARRS catalog is M_500_=1.6_-0.8_^+0.7^x10^14^M_{sun}_, with the Sunyaev-Zel'dovich data confirming that we detect clusters with masses up to M_500_~5x10^14^M_{sun}_ (_M200_~10^15^M_{sun}_).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/162/229
- Title:
- 13 Magellanic Clouds metal-poor stars
- Short Name:
- J/AJ/162/229
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- The chemical abundances of a galaxy's metal-poor stellar population can be used to investigate the earliest stages of its formation and chemical evolution. The Magellanic Clouds are the most massive of the Milky Way's satellite galaxies and are thought to have evolved in isolation until their recent accretion by the Milky Way. Unlike the Milky Way's less massive satellites, little is known about the Magellanic Clouds' metal-poor stars. We have used the mid-infrared metal-poor star selection of Schlaufman & Casey and archival data to target nine LMC and four SMC giants for high-resolution Magellan/MIKE spectroscopy. These nine LMC giants with -2.4<~[Fe/H]<~-1.5 and four SMC giants with -2.6<~[Fe/H]<~-2.0 are the most metal-poor stars in the Magellanic Clouds yet subject to a comprehensive abundance analysis. While we find that at constant metallicity these stars are similar to Milky Way stars in their {alpha}, light, and iron-peak elemental abundances, both the LMC and SMC are enhanced relative to the Milky Way in the r-process element europium. These abundance offsets are highly significant, equivalent to 3.9{sigma} for the LMC, 2.7{sigma} for the SMC, and 5.0{sigma} for the complete Magellanic Cloud sample. We propose that the r-process enhancement of the Magellanic Clouds' metal-poor stellar population is a result of the Magellanic Clouds' isolated chemical evolution and long history of accretion from the cosmic web combined with r-process nucleosynthesis on a timescale longer than the core-collapse supernova timescale but shorter than or comparable to the thermonuclear (i.e., Type Ia) supernova timescale.
- ID:
- ivo://CDS.VizieR/J/A+A/456/451
- Title:
- Magellanic Clouds PNe abundances
- Short Name:
- J/A+A/456/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of an optical spectroscopic study of planetary nebulae in the LMC and SMC. The first paper, Leisy & Dennefeld (1996, Cat. <J/A+AS/116/95>), discussed the CNO cycle for those objects where C abundances were available. In this paper we concentrate more on other elemental abundances (such as O, Ne, S, Ar) and their implications for the evolution of the progenitor stars. We use a much larger sample of 183 objects, of which 65 are our own observations, where the abundances have been re-derived in a homogeneous way. For 156 of them, the quality of data is considered to be satisfactory for further analysis.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/11
- Title:
- Magellan/IMACS spectra of Crater II & Hercules
- Short Name:
- J/ApJ/883/11
- Date:
- 21 Jan 2022 09:25:05
- Publisher:
- CDS
- Description:
- We investigate the possibility that the dwarf galaxies Crater II and Hercules have previously been tidally stripped by the Milky Way. We present Magellan/IMACS spectra of candidate member stars in both objects. We identify 37 members of Crater II, 25 of which have velocity measurements in the literature, and we classify three stars within that subset as possible binaries. We find that including or removing these binary candidates does not change the derived velocity dispersion of Crater II. Excluding the binary candidates, we measure a velocity dispersion of {sigma}_Vlos_=2.7_-0.4_^+0.5^km/s, corresponding to M/L=47_-13_^+17^M_{sun}_/L_{sun}_. We measure a mean metallicity of [Fe/H]=-1.95_-0.05_^+0.06^, with a dispersion of {sigma}_[Fe/H]_=0.18_-0.08_^+0.06^. Our velocity dispersion and metallicity measurements agree with previous measurements for Crater II, and confirm that the galaxy resides in a kinematically cold dark-matter halo. We also search for spectroscopic members stripped from Hercules in the possible extratidal stellar overdensities surrounding the dwarf. For both galaxies, we calculate proper motions using Gaia DR2 astrometry, and use their full 6D phase space information to evaluate the probability that their orbits approach sufficiently close to the Milky Way to experience tidal stripping. Given the available kinematic data, we find a probability of ~40% that Hercules has suffered tidal stripping. The proper motion of Crater II makes it almost certain to be stripped.
- ID:
- ivo://CDS.VizieR/J/AJ/154/113
- Title:
- Magellan/M2FS spectroscopy of Abell 267
- Short Name:
- J/AJ/154/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a pilot program to use the Magellan/M2FS spectrograph to survey the galactic populations and internal kinematics of galaxy clusters. For this initial study, we present spectroscopic measurements for 223 quiescent galaxies observed along the line of sight of the galaxy cluster Abell 267 (z~0.23). We develop a Bayesian method for modeling the integrated light from each galaxy as a simple stellar population, with free parameters that specify the redshift (v_los_/c) and characteristic age, metallicity ([Fe/H]), alpha-abundance ([{alpha}/Fe]), and internal velocity dispersion ({sigma}_int_) for individual galaxies. Parameter estimates derived from our 1.5hr observation of A267 have median random errors of {sigma}_Vlos_=20km/s, {sigma}_Age_=1.2Gyr, {sigma}_[Fe/H]_=0.11dex, {sigma}_[{alpha}/Fe]_=0.07dex, and {sigma}_{sigma}int_=20km/s. In a companion paper, we use these results to model the structure and internal kinematics of A267.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/53
- Title:
- Magellan/M2FS spectroscopy of Tucana 2 and Grus 1
- Short Name:
- J/ApJ/819/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 147 stellar targets along the line of sight to the newly discovered "ultrafaint" stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line of sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of 8.6^+4.4^_-2.7_km/s about a mean of -129.1+/-3.5km/s (solar rest frame), and to estimate a mean metallicity of [Fe/H]=-2.23^+0.18^_-0.12_. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass 2.7^+3.1^_-1.3_x10^6^M_{sun}_ enclosed within the central ~160pc, and dynamical mass-to-light ratio 1913^+2234^_-950_M_{sun}_/L_{nu},{sun}_. For Gru 1 we estimate a mean velocity of -140.5^+2.4^_-1.6_km/s and a mean metallicity of [Fe/H]=-1.42^+0.55^_-0.42_ but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within a distance of <~300pc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/776/114
- Title:
- MAGIICAT. I. MgII Absorber-Galaxy Catalog
- Short Name:
- J/ApJ/776/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the MgII Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07<=z<=1.1) galaxies with measurements of MgII {lambda}{lambda}2796,2803 absorption from their circumgalactic medium within projected distances of 200kpc from background quasars. In this work, we present "isolated" galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100kpc and a line of sight velocity separation of 500km/s. We standardized all galaxy properties to the {Lambda}CDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame MgII equivalent width, W_r_(2796), versus galaxy redshift. The well-known anti-correlation between W_r_(2796) and quasar-galaxy impact parameter, D, is significant to the 8{sigma} level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W_r_(2796) and redshift subsamples: "weak absorbing" [W_r_(2796)<0.3{AA}], "strong absorbing" [W_r_(2796)>=0.3{AA}], low redshift (z{<}<z>), and high redshift (z{>=}<z>), where <z> = 0.359 is the median galaxy redshift. Rest-frame color B-K correlates with M_K_ at the 8{sigma} level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6{sigma}). Using M_K_ as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, MgII absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/145
- Title:
- MagLiteS Carina II and Carina III spectroscopy
- Short Name:
- J/ApJ/857/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the Carina II (CarII) and Carina III (CarIII) dwarf galaxy candidates, recently discovered in the Magellanic Satellites Survey (MagLiteS). We identify 18 member stars in Car II, including two binaries with variable radial velocities and two RR Lyrae stars. The other 14 members have a mean heliocentric velocity v_hel_=477.2+/-1.2km/s and a velocity dispersion of {sigma}_v_=3.4_-0.8_^+1.2^km/s. Assuming Car II is in dynamical equilibrium, we derive a total mass within the half-light radius of 1.0_-0.4_^+0.8^x10^6^M_{sun}_, indicating a mass-to-light ratio of 369_-161_^+309^M_{sun}_/L_{sun}_. From equivalent width measurements of the calcium triplet lines of nine red giant branch (RGB) stars, we derive a mean metallicity of [Fe/H]=-2.44+/-0.09 with dispersion {sigma}_[Fe/H]_=0.22_-0.07_^+0.10^. Considering both the kinematic and chemical properties, we conclude that CarII is a dark-matter-dominated dwarf galaxy. For CarIII, we identify four member stars, from which we calculate a systemic velocity of v_hel_=284.6_-3.1_^+3.4^km/s. The brightest RGB member of CarIII has a metallicity of [Fe/H]=-1.97+/-0.12. Due to the small size of the Car III spectroscopic sample, we cannot conclusively determine its nature. Although these two systems have the smallest known physical separation ({Delta}d~10kpc) among Local Group satellites, the large difference in their systemic velocities, ~200km/s, indicates that they are unlikely to be a bound pair. One or both systems are likely associated with the Large Magellanic Cloud (LMC), and may remain LMC satellites today. No statistically significant excess of {gamma}-ray emission is found at the locations of Car II and Car III in eight years of Fermi-LAT data.
- ID:
- ivo://CDS.VizieR/J/AJ/153/144
- Title:
- Magnetic CVs spectra and other variable objects
- Short Name:
- J/AJ/153/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), provides a unique opportunity to discover variable sources and improves the statistical samples of such classes of objects. Our goal is the discovery of magnetic Cataclysmic Variables (mCVs). These are rare objects that probe interesting accretion scenarios controlled by the white-dwarf magnetic field. In particular, improved statistics of mCVs would help to address open questions on their formation and evolution. We performed an optical spectroscopy survey to search for signatures of magnetic accretion in 45 variable objects selected mostly from the CRTS. In this sample, we found 32 CVs, 22 being mCV candidates, 13 of which were previously unreported as such. If the proposed classifications are confirmed, it would represent an increase of 4% in the number of known polars and 12% in the number of known IPs. A fraction of our initial sample was classified as extragalactic sources or other types of variable stars by the inspection of the identification spectra. Despite the inherent complexity in identifying a source as an mCV, variability-based selection, followed by spectroscopic snapshot observations, has proved to be an efficient strategy for their discoveries, being a relatively inexpensive approach in terms of telescope time.
- ID:
- ivo://CDS.VizieR/J/AJ/159/114
- Title:
- Magnetic CVs spectra & other variable objects II.
- Short Name:
- J/AJ/159/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper of a series presenting our search for magnetic cataclysmic variables (mCVs) among candidates selected mostly from the Catalina Real-Time Transient Survey. We present the identification spectra, obtained at the SOAR Telescope, as well as magnitudes and Gaia distances for 45 objects. Of these, 39 objects are identified as CVs, from which 8 targets show observational characteristics of mCVs, being 7 polars and 1 intermediate polar. The remaining 31 CVs in our sample are probably non-magnetic systems, in low (22 systems) or high (9 systems) accretion states. Six targets of the sample are not CVs (5 active galactic nuclei and 1 T-Tauri star). Among the 8 objects with mCV spectra, 6 are new classifications. Three polars were observed in low-accretion state, either revealing photospheric features of the secondary star and allowing the estimation of their spectral type, or presenting H{beta} Zeeman components associated to the white dwarf (WD) magnetic field. In addition to the results obtained in the first paper of the series, and depending on the confirmation of these classifications by observational follow-up, our results would increase the sample of known polars by about 9%.
