- ID:
- ivo://CDS.VizieR/J/A+A/624/A19
- Title:
- GALAH survey, chemodynamical analyse with TGAS
- Short Name:
- J/A+A/624/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The overlap between the spectroscopic Galactic Archaeology with HERMES (GALAH) survey and Gaia provides a high-dimensional chemodynamical space of unprecedented size. We present a first analysis of a subset of this overlap, of 7066 turn-off, and sub-giant stars. These stars have spectra from the GALAH survey and high parallax precision from the Gaia DR1 Tycho-Gaia Astrometric Solution. We investigate correlations between chemical compositions, ages, and kinematics for this sample. Stellar parameters and elemental abundances are derived from the GALAH spectra with the spectral synthesis code Spectroscopy Made Easy. We determine kinematics and dynamics, including action angles, from the Gaia astrometry and GALAH radial velocities. Stellar masses and ages are determined with Bayesian isochrone matching, using our derived stellar parameters and absolute magnitudes. We report measurements of Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, as well as Ba and we note that we have employed non-LTE calculations for Li, O, Al, and Fe. We show that the use of astrometric and photometric data improves the accuracy of the derived spectroscopic parameters, especially log g. Focusing our investigation on the correlations between stellar age, iron abundance [Fe/H], and mean alpha-enhancement [{alpha}/Fe] of the magnitude-selected sample, we recover the result that stars of the high-{alpha} sequence are typically older than stars in the low-{alpha} sequence, the latter spanning iron abundances of -0.7<[Fe/H]<+0.5. While these two sequences become indistinguishable in [{alpha}/Fe] vs. [Fe/H] at the metal-rich regime, we find that age can be used to separate stars from the extended high-alpha and the low-alpha sequence even in this regime. When dissecting the sample by stellar age, we find that the old stars (>8Gyr) have lower angular momenta L_z_ than the Sun, which implies that they are on eccentric orbits and originate from the inner disc. Contrary to some previous smaller scale studies we find a continuous evolution in the high-alpha-sequence up to super-solar [Fe/H] rather than a gap, which has been interpreted as a separate 'high-alpha metal-rich' population. Stars in our sample that are younger than 10Gyr, are mainly found on the low alpha-sequence and show a gradient in L_z_ from low [Fe/H] (L_z_>L_z,{sun}_) towards higher [Fe/H] (L_z_<L_z,{sun}_), which implies that the stars at the ends of this sequence are likely not originating from the close solar vicinity.
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Search Results
612. GALAH Survey DR2
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/4513
- Title:
- GALAH Survey DR2
- Short Name:
- J/MNRAS/478/4513
- Date:
- 04 Feb 2022 00:12:04
- Publisher:
- CDS
- Description:
- The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of the Milky Way, designed to deliver complementary chemical information to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342 682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community. Here we present the target selection, observation, data reduction, and detailed explanation of how the spectra were analysed to estimate stellar parameters and element abundances. For the stellar analysis, we have used a multistep approach. We use the physics-driven spectrum synthesis of Spectroscopy Made Easy (SME) to derive stellar labels (Teff, logg, [Fe/H], [X/Fe], vmic, vsini, A_KS_) for a representative training set of stars. This information is then propagated to the whole sample with the data-driven method of The Cannon. Special care has been exercised in the spectral synthesis to only consider spectral lines that have reliable atomic input data and are little affected by blending lines. Departures from local thermodynamic equilibrium (LTE) are considered for several key elements, including Li, O, Na, Mg, Al, Si, and Fe, using 1D marcs stellar atmosphere models. Validation tests including repeat observations, Gaia benchmark stars, open and globular clusters, and K2 asteroseismic targets lend confidence to our methods and results. Combining the GALAH DR2 catalogue with the kinematic information from Gaia will enable a wide range of Galactic Archaeology studies, with unprecedented detail, dimensionality, and scope.
- ID:
- ivo://CDS.VizieR/J/ApJ/653/1004
- Title:
- Galaxies at 1.4<~z<~3.0 in GOODS-North Field
- Short Name:
- J/ApJ/653/1004
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a spectroscopic survey with LRIS-B on Keck of more than 280 star-forming galaxies and AGNs at redshifts 1.4~<z~<3.0 in the GOODS-N field. Candidates are selected by their UnGR colors using the "BM/BX" criteria to target redshift 1.4~<z~<2.5 galaxies and the LBG criteria to target redshift z~3 galaxies; combined these samples account for ~25%-30% of the R and Ks band counts to R=25.5 and Ks(AB)=24.4, respectively. The 212 BM/BX galaxies and 74 LBGs constitute the largest spectroscopic sample of galaxies at z>1.4 in GOODS-N. Extensive multiwavelength data allow us to investigate the stellar populations, stellar masses, bolometric luminosities (Lbol), and extinction z~2 of galaxies. Deep Chandra and Spitzer data indicate that the sample includes galaxies with a wide range in Lbol (~10^10^ to >10^12^L_{sun}_) and 4 orders of magnitude in dust obscuration (Lbol/LUV).
- ID:
- ivo://CDS.VizieR/J/AJ/132/926
- Title:
- Galaxies in the Hubble Ultra Deep Field
- Short Name:
- J/AJ/132/926
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present aperture-matched point-spread function (PSF)corrected BVi'z'JH photometry and Bayesian photometric redshifts (BPZ) for objects detected in the Hubble Ultra Deep Field (UDF), 8042 of which are detected at the 10 level (e.g., i'<29.01 or z'<28.43). Most of our objects are defined identically to those in the public STScI catalogs, enabling a straightforward object-by-object comparison. We have combined detections from i', z', J+H, and B+V+i'+ z' images into a single comprehensive segmentation map. Using a new program called SExSeg, we are able to force this segmentation map into SExtractor for photometric analysis. The resulting photometry is corrected for the wider NIC3 PSFs using our ColorPro software. We also correct for the ACS z'-band PSF halo. Offsets are applied to our NIC3 magnitudes, which are found to be too faint relative to the ACS fluxes. Based on BPZ spectral energy distribution (SED) fits to objects of known spectroscopic redshift, we derived corrections of -0.30+/-0.03mag in J and -0.18+/-0.04mag in H. Our offsets appear to be supported by a recent recalibration of the UDF NIC3 images combined with nonlinearity measured in NICMOS itself. The UDF reveals a large population of faint blue galaxies (presumably young starbursts), bluer than those observed in the original Hubble Deep Fields.
- ID:
- ivo://CDS.VizieR/J/ApJ/816/98
- Title:
- Galaxies in X-ray clusters with DES. I. Stellar mass
- Short Name:
- J/ApJ/816/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the science verification data of the Dark Energy Survey for a new sample of 106 X-ray selected clusters and groups, we study the stellar mass growth of bright central galaxies (BCGs) since redshift z~1.2. Compared with the expectation in a semi-analytical model applied to the Millennium Simulation, the observed BCGs become under-massive/under-luminous with decreasing redshift. We incorporate the uncertainties associated with cluster mass, redshift, and BCG stellar mass measurements into an analysis of a redshift-dependent BCG-cluster mass relation, m_*_{propto}(M_200_/1.5x10^14^M_{sun}_)^0.24+/-0.08^(1+z)^-0.19+/-0.34, and compare the observed relation to the model prediction. We estimate the average growth rate since z=1.0 for BCGs hosted by clusters of M_200,z_=10^13.8^M_{sun}_; at z=1.0: m_*,BCG_ appears to have grown by 0.13+/-0.11dex, in tension at the ~2.5{sigma} significance level with the 0.40 dex growth rate expected from the semi-analytic model. We show that the build-up of extended intracluster light after z=1.0 may alleviate this tension in BCG growth rates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/3875
- Title:
- Galaxy And Mass Assembly (GAMA): DR3
- Short Name:
- J/MNRAS/474/3875
- Date:
- 19 Jan 2022 09:03:58
- Publisher:
- CDS
- Description:
- We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multiwavelength photometric survey in three equatorial regions each of 60.0deg^2^ (G09, G12, and G15), and two southern regions of 55.7deg^2^ (G02) and 50.6deg^2^ (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS (Herschel - Astrophysical Terahertz Large Area Survey) sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5 per cent redshift complete to r<19.8mag over an area of 19.5deg^2^, with 20086 galaxy redshifts, that overlaps substantially with the XXL survey (X-ray) and VIPERS (redshift survey). In the equatorial regions, the main survey has even higher completeness (98.5 per cent), and spectra for about 75 per cent of H-ATLAS filler targets were also obtained. This filler sample extends spectroscopic redshifts, for probable optical counterparts to H-ATLAS submillimetre sources, to 0.8mag deeper (r<20.6mag) than the GAMA main survey. There are 25814 galaxy redshifts for H-ATLAS sources from the GAMA main or filler surveys. GAMA DR3 is available at the survey website (www.gama-survey.org/dr3/).
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/2087
- Title:
- Galaxy And Mass Assembly (GAMA): DR2
- Short Name:
- J/MNRAS/452/2087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. Covering an area of ~286deg^2^ (split among five survey regions) down to a limiting magnitude of r<19.8mag, we have collected spectra and reliable redshifts for 238000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1nm-1m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Sersic fits, stellar masses, H{alpha}-derived star formation rates, environment information, and group properties for all galaxies with r<19.0mag in two of our survey regions, and for all galaxies with r<19.4mag in a third region (72225 objects in total). The data base serving these data is available at http://www.gama-survey.org/.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/971
- Title:
- Galaxy And Mass Assembly (GAMA) DR1
- Short Name:
- J/MNRAS/413/971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy and Mass Assembly (GAMA) survey has been operating since 2008 February on the 3.9-m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution of R~1300 for 120862 Sloan Digital Sky Survey selected galaxies. The target catalogue constitutes three contiguous equatorial regions centred at 9h (G09), 12h (G12) and 14.5h (G15) each of 12x4deg^2^ to limiting fluxes of r_pet_<19.4, r_pet_<19.8 and r_pet_<19.4 mag, respectively (and additional limits at other wavelengths). Spectra and reliable redshifts have been acquired for over 98 per cent of the galaxies within these limits. Here we present the survey footprint, progression, data reduction, redshifting, re-redshifting, an assessment of data quality after 3yr, additional image analysis products (including ugrizYJHK photometry, Sersic profiles and photometric redshifts), observing mask and construction of our core survey catalogue (GamaCore). From this we create three science-ready catalogues: GamaCoreDR1 for public release, which includes data acquired during year 1 of operations within specified magnitude limits (2008 February to April); GamaCoreMainSurvey containing all data above our survey limits for use by the GAMA Team and collaborators; and GamaCoreAtlasSV containing year 1, 2 and 3 data matched to Herschel-ATLAS science demonstration data. These catalogues along with the associated spectra, stamps and profiles can be accessed via the GAMA website: http://www.gama-survey.org/
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/2144
- Title:
- Galaxy And Mass Assembly: red & blue galaxies
- Short Name:
- J/MNRAS/446/2144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the mass functions for generically red and blue galaxies, using a z<0.12 sample of logM_*_>8.7 field galaxies from the Galaxy And Mass Assembly (GAMA) survey. Our motivation is that, as we show, the dominant uncertainty in existing measurements stems from how "red" and "blue" galaxies have been selected/defined. Accordingly, we model our data as two naturally overlapping populations, each with their own mass function and colour-mass relation, which enables us characterize the two populations without having to specify a priori which galaxies are "red" and "blue". Our results then provide the means to derive objective operational definitions for the terms "red" and "blue", which are based on the phenomenology of the colour-mass diagrams. Informed by this descriptive modelling, we show that (1) after accounting for dust, the stellar colours of "blue" galaxies do not depend strongly on mass; (2) the tight, flat "dead sequence" does not extend much below logM_*_~10.5; instead, (3) the stellar colours of "red" galaxies vary rather strongly with mass, such that lower mass "red" galaxies have bluer stellar populations; (4) below logM_*_~9.3, the "red" population dissolves into obscurity, and it becomes problematic to talk about two distinct populations; as a consequence, (5) it is hard to meaningfully constrain the shape, including the existence of an upturn, of the "red" galaxy mass function below logM_*_~9.3. Points 1-4 provide meaningful targets for models of galaxy formation and evolution to aim for.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/127
- Title:
- Galaxy clusters discovered in the SPT survey
- Short Name:
- J/ApJ/763/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of galaxy cluster candidates, selected through their Sunyaev-Zel'dovich (SZ) effect signature in the first 720deg^2^ of the South Pole Telescope (SPT) survey. This area was mapped with the SPT in the 2008 and 2009 austral winters to a depth of ~18{mu}K_CMB_-arcmin at 150GHz; 550deg^2^ of it was also mapped to ~44{mu}K_CMB_-arcmin at 95GHz. Based on optical imaging of all 224 candidates and near-infrared imaging of the majority of candidates, we have found optical and/or infrared counterparts for 158, which we then classify as confirmed galaxy clusters. Of these 158 clusters, 135 were first identified as clusters in SPT data, including 117 new discoveries reported in this work. This catalog triples the number of confirmed galaxy clusters discovered through the SZ effect. We report photometrically derived (and in some cases spectroscopic) redshifts for confirmed clusters and redshift lower limits for the remaining candidates. The catalog extends to high redshift with a median redshift of z=0.55 and maximum confirmed redshift of z=1.37. Forty-five of the clusters have counterparts in the ROSAT bright or faint source catalogs from which we estimate X-ray fluxes. Based on simulations, we expect the catalog to be nearly 100% complete above M_500_{approx}5x10^14^M_{sun}_h^-1^_70_ at z>~0.6. There are 121 candidates detected at signal-to-noise ratio greater than five, at which the catalog purity is measured to be 95%.
