- ID:
- ivo://CDS.VizieR/J/A+A/516/A4
- Title:
- NGC1600, NGC4125, NGC7619 extended spectroscopy
- Short Name:
- J/A+A/516/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high quality long slit spectra along the major and minor axes out to 1.5-2R_e_ (14-22kpc) of three bright elliptical galaxies (NGC1600, NGC4125, NGC7619) obtained at the Hobby-Eberly Telescope (HET). We derive stellar kinematic profiles and Lick/IDS indices (H{beta}, Mgb, Fe_{5015}, Fe_{5270}, Fe_{5335}, Fe_{5406}). Moreover, for NGC4125 we derive gas kinematics and emission line strengths. We model the absorption line strengths using Simple Stellar Populations models that take into account the variation of {alpha}/Fe and derive ages, total metallicity and element abundances. Overall, we find that the three galaxies have old and {alpha}/Fe overabundant stellar populations with no significant gradients. The metallicity is supersolar at the center with a strong negative radial gradient. For NGC4125, several pieces of evidence point to a recent dissipational merger event. We calculate the broad band color profiles with the help of SSP models. All of the colors show sharp peaks at the center of the galaxies, mainly caused by the metallicity gradients, and agree well with the measured colors. Using the Schwarzschild's axisymmetric orbit superposition technique, we model the stellar kinematics to constrain the dark halos of the galaxies. We use the tight correlation between the Mgb strength and local escape velocity to set limits on their extent by testing different halo sizes. Logarithmic halos cut at 60kpc minimize the overall scatter of the Mgb-V_esc_ relation. Larger cutoff radii are found if the dark matter density profile is decreasing more steeply at large radii.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/3776
- Title:
- NGC 3115 Stellar Populations and Kinematics
- Short Name:
- J/MNRAS/487/3776
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a combination of the Schwarzschild orbit-superposition dynamical modelling technique with the spatially-resolved mean stellar age and metallicity maps to uncover the formation history of galaxies. We apply this new approach to a remarkable 5-pointing mosaic of VLT/MUSE observations obtained by Guerou et al. (2016A&A...591A.143G, Cat. J/A+A/591/A143) extending to a maximum galactocentric distance of ~120'' (5.6kpc) along the major axis, corresponding to ~2.5R_e. Our method first identifies 'families' of orbits from the dynamical model that represent dynamically distinct structures of the galaxy. Individual ages and metallicities of these components are then fit for using the stellar-population information. Our results highlight components of the galaxy that are distinct in the combined stellar dynamics/populations space, which implies distinct formation paths. We find evidence for a dynamically-cold, metal-rich disk, consistent with a gradual in-situ formation. This disk is embedded in a generally-old population of stars, with kinematics ranging from dispersion-dominated in the centre to an old, diffuse, metal-poor stellar halo at the extremities. We find also a direct correlation between the dominant dynamical support of these components, and their associated age, akin to the relation observed in the Milky Way. This approach not only provides a powerful model for inferring the formation history of external galaxies, but also paves the way to a complete population-dynamical model.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/52
- Title:
- NGFS. III. Dwarf galaxies in outer regions
- Short Name:
- J/ApJ/859/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 271 previously undetected dwarf galaxies in the outer Fornax cluster regions at radii r_vir_/4<r<r_vir_/2 using data from the Next Generation Fornax Survey (NGFS) with deep coadded u', g', and i' images obtained with Blanco/DECam at Cerro Tololo Interamerican Observatory. From the 271 dwarf candidates, we find 39 to be nucleated. Together with our previous study of the central Fornax region, the new dwarfs detected with NGFS data number 392, of which 56 are nucleated. The total Fornax dwarf galaxy population from NGFS and other catalogs rises, therefore, to a total of 643 with 181 being nucleated, yielding an overall nucleation fraction of 28%. The absolute i'-band magnitudes for the outer NGFS dwarfs are in the range -18.80<=M_i'_<=-8.78 with effective radii r_eff,i'_=0.18-2.22kpc and an average Sersic index <n>_i'_=0.81. Nonnucleated dwarfs are found to be fainter and smaller by {Delta}<M_i'_>=2.25mag and {Delta}<r_eff,i'_>=0.4kpc than the nucleated dwarfs. We demonstrate a significant clustering of dwarf galaxies on scales <~100kpc, and projected surface number density profile estimates, {Sigma}_N_(r), show a concentration of dwarfs in the Fornax core region within r<~350kpc. {Sigma}_N_(r) has a flat distribution up to ~350kpc, beyond which it declines for the nonnucleated dwarfs. The nucleated dwarfs have a steeper {Sigma}N(r) distribution, are more concentrated toward NGC 1399, and are decreasing rapidly outwards. This is the first time the transition from cluster to field environment has been established for the very faint dwarf galaxy population with robust sample statistics.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/30
- Title:
- NGVS VI. Ultra-compact dwarfs in M87
- Short Name:
- J/ApJ/802/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of ultra-compact dwarfs (UCDs; r_h_>~10pc) --objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies-- has been hotly debated in the 15yrs since their discovery. Even whether UCDs should be considered galactic in origin, or simply the most extreme star clusters, is not yet settled. We present the dynamical properties of 97 spectroscopically confirmed UCDs and 911 GCs associated with the central cD galaxy of the Virgo cluster, M87. Our UCDs, of which 89% have M_*_>~2x10^6^M_{sun}_ and 92% are as blue as the classic blue GCs, nearly triple the confirmed sample of Virgo UCDs, providing by far the best opportunity for studying global dynamics of a UCD system. We found that (1) UCDs have a surface number density profile that is shallower than that of blue GCs in the inner ~70kpc and as steep as that of red GCs at larger radii; (2) UCDs exhibit a significantly stronger rotation than GCs, and blue GCs seem to have a velocity field that is more consistent with that of the surrounding dwarf ellipticals than with that of UCDs; (3) UCDs have an orbital anisotropy profile that is tangentially biased at radii <~40kpc and radially biased farther out, whereas blue GCs become more tangentially biased at larger radii beyond ~40kpc; (4) GCs with M_*_>~2x10^6^M_{sun}_ have rotational properties indistinguishable from the less massive ones, suggesting that it is the size, instead of mass, that differentiates UCDs from GCs as kinematically distinct populations. We conclude that most UCDs in M87 are not consistent with being merely the most luminous and extended examples of otherwise normal GCs. The radially biased orbital structure of UCDs at large radii is in general agreement with the "tidally threshed dwarf galaxy" scenario.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/128
- Title:
- NGVS. XIV. Bona fide Virgo cluster members
- Short Name:
- J/ApJ/890/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Next Generation Virgo Cluster Survey (NGVS) was designed to provide a deep census of baryonic structures in the Virgo cluster. The survey covers the 104deg^2^ area from the core of Virgo out to one virial radius, in the u*griz bandpasses, to a point-source depth of g~25.9mag (10{sigma}) and a single pixel surface brightness limit of {mu}_g_~29mag/arcsec^2^ (2{sigma} above the sky). Here we present the final catalog of 404 Virgo galaxies located within a 3.71deg^2^ (0.3Mpc^2^) region centered on M87, Virgo's dominant galaxy. Of these, 154 were previously uncataloged and span the range 17.8mag<g<23.7mag (-13.4mag<M_g_{<}-7.4mag at the 16.5Mpc distance of Virgo). Extensive simulations show that the NGVS catalog is complete down to g=18.6mag (M_g_=-12.5mag, corresponding to a stellar mass M~1.6x10^7^M_{sun}_ for an old stellar population), and 50% complete at g=22.0mag (M_g_=-9.1mag, M~6.2x10^5^M_{sun}_). The NGVS 50% completeness limit is 3mag deeper than that of the Virgo Cluster Catalog (VCC), which has served as Virgo's reference standard for over a quarter century, and 2mag deeper than the VCC detection limit. We discuss the procedure adopted for the identification of objects and the criteria used to assess cluster membership. For each of the 404 galaxies in the NGVS Virgo Cluster core catalog, we present photometric and structural parameters based on a nonparametric curve-of-growth and isophotal analysis, as well as parametric (Sersic, double-Sersic, and/or core-Sersic) fits to the one-dimensional surface brightness profiles and two-dimensional light distributions.
- ID:
- ivo://CDS.VizieR/J/AJ/137/2981
- Title:
- Northern Optical Cluster Survey. III.
- Short Name:
- J/AJ/137/2981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z<~0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less well-calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II (Cat. J/AJ/125/2064). The complete survey covers 11411deg^2^, with over 15000 candidate clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/3570
- Title:
- Nuclear star clusters in 228 spiral galaxies
- Short Name:
- J/MNRAS/441/3570
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of photometric and structural properties of 228 nuclear star clusters (NSCs) in nearby late-type disc galaxies. These new measurements are derived from a homogeneous analysis of all suitable Wide Field Planetary Camera 2 (WFPC2) images in the Hubble Space Telescope (HST) archive. The luminosity and size of each NSC are derived from an iterative point spread function (PSF) fitting technique, which adapts the fitting area to the effective radius (r_eff_) of the NSC and uses a WFPC2-specific PSF model tailored to the position of each NSC on the detector. The luminosities of NSCs are <=10^8^L_V,{sun}_, and their integrated optical colours suggest a wide spread in age. We confirm that most NSCs have sizes similar to globular clusters (GCs), but find that the largest and brightest NSCs occupy the regime between ultra-compact dwarf (UCD) and the nuclei of early-type galaxies in the size-luminosity plane. The overlap in size, mass, and colour between the different incarnations of compact stellar systems provides a support for the notion that at least some UCDs and the most massive Galactic GCs may be remnant nuclei of disrupted disc galaxies. We find tentative evidence for the NSCs' r_eff_ to be smaller when measured in bluer filters and discuss possible implications of this result. We also highlight a few examples of complex nuclear morphologies, including double nuclei, extended stellar structures, and nuclear F606W excess from either recent (circum-)nuclear star formation and/or a weak active galactic nucleus. Such examples may serve as case studies for ongoing NSC evolution via the two main suggested mechanisms, namely cluster merging and in situ star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/2122
- Title:
- Nuclear star clusters photometric masses
- Short Name:
- J/MNRAS/457/2122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic nuclei typically host either a nuclear star cluster (NSC, prevalent in galaxies with masses <~10^10^M_{sun}_) or a massive black hole (MBH, common in galaxies with masses >~10^12^M_{sun}_). In the intermediate-mass range, some nuclei host both an NSC and an MBH. In this paper, we explore scaling relations between NSC mass (M_*,gal_) and host-galaxy total stellar mass (M_NSC_) using a large sample of NSCs in late- and early-type galaxies, including a number of NSCs harbouring an MBH. Such scaling relations reflect the underlying physical mechanisms driving the formation and (co)evolution of these central massive objects. We find ~1.5{sigma} significant differences between NSCs in late- and early-type galaxies in the slopes and offsets of the relations r_eff,NSC_-M_NSC_, r_eff,NSC_-M_*,gal_ and M_NSC_-M_*,gal_, in the sense that (i) NSCs in late types are more compact at fixed M_NSC_ and M_*,gal_; and (ii) the M_NSC_-M_*,gal_ relation is shallower for NSCs in late types than in early types, similar to the M_BH-M_*,bulge relation. We discuss these results in the context of the (possibly ongoing) evolution of NSCs, depending on host-galaxy type. For NSCs with an MBH, we illustrate the possible influence of an MBH on its host NSC, by considering the ratio between the radius of the MBH sphere of influence and r_eff,NSC_. NSCs harbouring a sufficiently massive black hole are likely to exhibit surface brightness profile deviating from a typical King profile.
- ID:
- ivo://CDS.VizieR/J/MNRAS/363/1019
- Title:
- Nucleated dwarf ellipticals in Virgo cluster
- Short Name:
- J/MNRAS/363/1019
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using images from a charge-coupled device survey with the Wide Field Camera on the Isaac Newton Telescope, we performed B- and I-band photometry on 156 Virgo cluster dwarf elliptical (dE) galaxies, 25 candidate new cluster dwarfs, and nine candidate field dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/226
- Title:
- Nuker law parameters of early-type galaxies
- Short Name:
- J/ApJ/664/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine several HST investigations on the central structure of early-type galaxies to generate a large sample of surface photometry. The studies selected were those that used the "Nuker law" to characterize the inner light distributions of the galaxies. The sample comprises WFPC1 and WFPC2 V-band observations published earlier by our group, R-band WFPC2 photometry of Rest et al. (2001AJ....121.2431R), NICMOS H-band photometry by Ravindranath et al. (2001AJ....122..653R) and Quillen et al. (2000ApJS..128...85Q), and the brightest cluster galaxy WFPC2 I-band photometry of Laine et al. (2003, Cat. J/AJ/125/478).
