On the stellar kinematics and mass of the Virgo ultradiffuse galaxy VCC 1287

ABSTRACT Here, we present a kinematical analysis of the Virgo cluster ultradiffuse galaxy (UDG) VCC 1287 based on data taken with the Keck Cosmic Web Imager (KCWI). We confirm VCC 1287’s association both with the Virgo cluster and its globular cluster (GC) system, measuring a recessional velocity of 1116 ± 2 km s−1. We measure a stellar velocity dispersion (19 ± 6 km s−1) and infer both a dynamical mass ($1.11^{+0.81}_{-0.81} \times 10^{9} \ \mathrm{M_{\odot }}$) and mass-to-light ratio (M/L) ($13^{+11}_{-11}$) within the half-light radius (4.4 kpc). This places VCC 1287 slightly above the well-established relation for normal galaxies, with a higher M/L for its dynamical mass than normal galaxies. We use our dynamical mass, and an estimate of GC system richness, to place VCC 1287 on the GC number–dynamical mass relation, finding good agreement with a sample of normal galaxies. Based on a total halo mass derived from GC counts, we then infer that VCC 1287 likely resides in a cored or low-concentration dark matter halo. Based on the comparison of our measurements to predictions from simulations, we find that strong stellar feedback and/or tidal effects are plausibly the dominant mechanisms in the formation of VCC 1287. Finally, we compare our measurement of the dynamical mass with those for other UDGs. These dynamical mass estimates suggest relatively massive haloes and a failed galaxy origin for at least some UDGs.

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Dark matter and no dark matter: on the halo mass of NGC 1052

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2420 ◽

2019 ◽

Vol 489 (3) ◽

pp. 3665-3669

Author(s):

Duncan A Forbes ◽

Adebusola Alabi ◽

Jean P Brodie ◽

Aaron J Romanowsky

Keyword(s):

Dark Matter ◽

Globular Clusters ◽

Dark Matter Halo ◽

Host Galaxy ◽

Mass Relation ◽

Mean Velocity ◽

Dynamical Mass ◽

Mass Profile ◽

Velocity Dispersions ◽

Internal Velocity

ABSTRACT The NGC 1052 group, and in particular the discovery of two ultra-diffuse galaxies with very low internal velocity dispersions, has been the subject of much attention recently. Here we present radial velocities for a sample of 77 globular clusters associated with NGC 1052 obtained on the Keck telescope. Their mean velocity and velocity dispersion are consistent with that of the host galaxy. Using a simple tracer mass estimator, we infer the enclosed dynamical mass and dark matter fraction of NGC 1052. Extrapolating our measurements with a Navarro–Frenk–White (NFW) mass profile we infer a total halo mass of 6.2(±0.2) × 1012 M⊙. This mass is fully consistent with that expected from the stellar mass–halo mass relation, suggesting that NGC 1052 has a normal dark matter halo mass (i.e. it is not deficient in dark matter in contrast to two ultra-diffuse galaxies in the group). We present a phase-space diagram showing the galaxies that lie within the projected virial radius (390 kpc) of NGC 1052. Finally, we briefly discuss the two dark matter-deficient galaxies (NGC 1052-DF2 and NGC 1052-DF4) and consider whether modified Newtonian dynamics (MOND) can account for their low observed internal velocity dispersions.

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The Dark Blue Compact Dwarf Galaxy NGC 2915

Publications of the Astronomical Society of Australia ◽

10.1071/as97077 ◽

1997 ◽

Vol 14 (1) ◽

pp. 77-80 ◽

Cited By ~ 2

Author(s):

Gerhardt R. Meurer

Keyword(s):

Dark Matter ◽

Mass Distribution ◽

Dwarf Galaxy ◽

Dark Matter Halo ◽

High Mass ◽

Mass Star ◽

Normal Galaxies ◽

The Galaxy ◽

Dark Blue ◽

Blue Compact Dwarf Galaxy

AbstractRecent results on NGC 2915, the first blue compact dwarf galaxy to have its mass distribution modelled, are summarised. NGC 2915 is shown to have HI well beyond its detected optical extent. Its rotation curve is well determined and fit with maximum disk mass models. The dark matter halo dominates the mass distribution at nearly all radii, and has a very dense core compared to those of normal galaxies. High-mass star formation energises the HI in the centre of the galaxy, but appears to be maintained in viriai equilibrium with the dark matter halo. The implications of these results are briefly discussed.

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STELLAR KINEMATICS AND STRUCTURAL PROPERTIES OF VIRGO CLUSTER DWARF EARLY-TYPE GALAXIES FROM THE SMAKCED PROJECT. I. KINEMATICALLY DECOUPLED CORES AND IMPLICATIONS FOR INFALLEN GROUPS IN CLUSTERS

The Astrophysical Journal ◽

10.1088/0004-637x/783/2/120 ◽

2014 ◽

Vol 783 (2) ◽

pp. 120 ◽

Cited By ~ 35

Author(s):

E. Toloba ◽

P. Guhathakurta ◽

G. van de Ven ◽

S. Boissier ◽

A. Boselli ◽

...

Keyword(s):

Structural Properties ◽

Virgo Cluster ◽

Early Type ◽

Stellar Kinematics

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Origin of Nonaxisymmetric Features of Virgo Cluster Early-type Dwarf Galaxies. II. Tidal Effects on Disk Features and Stability

The Astrophysical Journal ◽

10.3847/1538-4357/ab5716 ◽

2019 ◽

Vol 887 (2) ◽

pp. 139 ◽

Cited By ~ 2

Author(s):

SungWon Kwak ◽

Woong-Tae Kim ◽

Soo-Chang Rey ◽

Thomas R. Quinn

Keyword(s):

Dwarf Galaxies ◽

Virgo Cluster ◽

Early Type ◽

Tidal Effects

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Stellar Populations and Kinematics in Seyfert Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306005126 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 71-75 ◽

Cited By ~ 1

Author(s):

N. V. Asari ◽

L. R. Vega ◽

A. Garcia-Rissmann ◽

R. M. González Delgado ◽

T. Storchi-Bergmann ◽

...

Keyword(s):

Equivalent Width ◽

Correlation Method ◽

Seyfert Galaxies ◽

Population Synthesis ◽

Stellar Kinematics ◽

Spatially Resolved ◽

Fitting Method ◽

Stellar Velocity ◽

Velocity Dispersions ◽

Nuclear Signal

AbstractOur aim is to study the stellar kinematics in hosts of AGN. We do so by measuring nuclear stellar velocity dispersions (σ⋆). Our sample comprises spectra of 78 objects, 69 of which are Seyfert galaxies, in the region around the λλ8498.02, 8542.09, 8662.14 Calcium triplet (CaT). We investigate two methods to measure σ⋆: (1) the direct fitting method (DFM), which makes use of our stellar population synthesis code Starlight, and (2) the cross-correlation method (CCM), for which we use the fxcor package in IRAF. Both methods yield velocity dispersions consistent to within 19 km/s on-average. We have also measured the CaT equivalent width (WCaT) and the λ3933 CaII K equivalent width (WK) for the objects in our sample. Other studies have shown that WK is a powerful tracer of starbursts in Seyfert nuclei, so we check if WCaT can be used in the same way. We have also analysed a sub-sample of 34 spatially resolved objects with reasonably good off-nuclear signal-to-noise. We study the spatial variations of both σ⋆ and WCaT. We see no dilution in WCaT for composite starburst + Seyfert 2 galaxies, in contrast to the dilution in the WK (studied by other authors) for the same objects.

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KMOS Clusters and VIRIAL GTO Surveys

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314009922 ◽

2014 ◽

Vol 10 (S309) ◽

pp. 293-294

Author(s):

D. Wilman ◽

R. Bender ◽

R. L. Davies ◽

J. T. Mendel ◽

J. Chan ◽

...

Keyword(s):

Near Infrared ◽

Early Type ◽

Dynamical Mass ◽

Fundamental Plane ◽

Cluster Galaxies ◽

Medium Resolution ◽

Stellar Velocity ◽

Time Observation ◽

Field Unit ◽

First Time

AbstractWe present the KMOS (K-band Multi-Object Spectrograph) Cluster and VIRIAL (VLT IRIFU Absorption Line) Guaranteed Time Observation (GTO) programs. KMOS provides 24 arms each feeding an integral field unit (14×14 spaxels of 0.2″ pixels) for IZ, YJ, H and K band near infrared (NIR) medium resolution spectroscopy (R ∼ 3500). Targets are selected from a 7.2′ diameter patrol field. Ultra-deep spectroscopy of ∼ 80 early-type cluster galaxies (∼ 20hr on source) and ∼ 200 (∼ 10hr on source) early-type field galaxies at 1 < z < 2 will dramatically improve the situation at z > 1 for which measurements of stellar velocity dispersions and absorption indices are limited to a few, often relatively young passively evolving galaxies (e.g. Bezanson 2013). In ESO Periods P92 and P93, 15 nights worth of data has been collected for KMOS-Clusters and 6 nights for VIRIAL: this will be supplemented with more data in upcoming semesters. All galaxies have multiband HST imaging including existing or upcoming WFC3 IR imaging, providing stellar mass maps and sizes. Combined with our dispersion measurements, this will allow us to examine the fundamental plane and the dynamical mass of a large sample of z > 1 galaxies for the first time, for both cluster and field galaxies.

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Galaxy population structure from proper motions

Symposium - International Astronomical Union ◽

10.1017/s0074180900242319 ◽

1985 ◽

Vol 106 ◽

pp. 165-166

Author(s):

N. Reid ◽

C. A. Murray

Keyword(s):

Preliminary Analysis ◽

Velocity Structure ◽

Proper Motions ◽

The Galaxy ◽

Stellar Velocity ◽

Galaxy Population ◽

Absolute Frame ◽

Image Position ◽

Overlap Method ◽

Good Agreement

We are currently engaged in astrometry of Kapteyn Selected Area photographic plates covering the period 1908 to the present day using the GALAXY measuring engine at RGO. Our intention is to use the apparent motions to investigate the stellar velocity structure within a kiloparsec of the Sun. We have completed a preliminary analysis of SA 68 (ℓ = 1110, b = 460), deriving positions and proper motions using the central overlap method on measures of plates spanning the period 1909 to 1980. These include the original (1909) and second epoch (1925) plates taken with the Radcliffe refractor at Oxford, and used in the compilation of the Radcliffe Catalogue (Knox-Shaw and Scott-Barrett, 1934), as well as more recent plates taken using the 26-inch refractor at Herstmonceux. For stars present on all thirteen exposures (including double exposures on the same plate) the internal residuals in positions in each co-ordinate are per plate, giving annual motions accurate to ~1 milli-arcsecond over the 71 year baseline. Since our plates have a limiting magnitude of only B ~15, we have used 17 stars in common with Chiu (1980) to transform our relative motions to the absolute frame. Our motions are in very good agreement with those by Chiu, with a scatter of less than 3 milliarcseconds in each co-ordinate and linearity of scale between the two datasets.

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NIHAO XXIV: rotation- or pressure-supported systems? Simulated Ultra Diffuse Galaxies show a broad distribution in their stellar kinematics

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2094 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4282-4292

Author(s):

Salvador Cardona-Barrero ◽

Arianna Di Cintio ◽

Christopher B A Brook ◽

Tomas Ruiz-Lara ◽

Michael A Beasley ◽

...

Keyword(s):

Galaxy Evolution ◽

Dark Matter Halo ◽

Stellar Kinematics ◽

Broad Distribution ◽

Hydrodynamical Simulation ◽

Low Surface Brightness ◽

Astrophysical Objects ◽

Comprehensive Survey ◽

Gas Accretion ◽

State Pressure

ABSTRACT In recent years, a new window on galaxy evolution opened, thanks to the increasing discovery of galaxies with a low-surface brightness, such as Ultra Diffuse Galaxies (UDGs). The formation mechanism of these systems is still a much debated question and so are their kinematical properties. In this work, we address this topic by analysing the stellar kinematics of isolated UDGs formed in the hydrodynamical simulation suite Numerical Investigation of a Hundred Astrophysical Objects (NIHAO). We construct projected line-of-sight velocity and velocity dispersion maps to compute the projected specific angular momentum, λR, to characterize the kinematical support of the stars in these galaxies. We found that UDGs cover a broad distribution, ranging from dispersion to rotation-supported galaxies, with similar abundances in both regimes. The degree of rotation support of simulated UDGs correlates with several properties such as galaxy morphology, higher H i fractions, and larger effective radii with respect to the dispersion-supported group, while the dark matter halo spin and mass accretion history are similar among the two populations. We demonstrate that the alignment of the infalling baryons into the protogalaxy at early z is the principal driver of the z = 0 stellar kinematic state: pressure-supported isolated UDGs form via misaligned gas accretion while rotation-supported ones build up their baryons in an ordered manner. Accounting for random inclination effects, we predict that a comprehensive survey will find nearly half of field UDGs to have rotationally supported stellar discs, when selecting UDGs with effective radius larger than 1 kpc.

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A flexible analytic model of cosmic variance in the first billion years

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2828 ◽

2020 ◽

Vol 499 (2) ◽

pp. 2401-2415

Author(s):

A C Trapp ◽

Steven R Furlanetto

Keyword(s):

Dark Matter ◽

Star Formation ◽

Luminosity Function ◽

Large Scale ◽

High Redshift ◽

Mass Function ◽

Dark Matter Halo ◽

Analytic Model ◽

Stellar Feedback ◽

High Redshift Universe

ABSTRACT Cosmic variance is the intrinsic scatter in the number density of galaxies due to fluctuations in the large-scale dark matter density field. In this work, we present a simple analytic model of cosmic variance in the high-redshift Universe (z ∼ 5–15). We assume that galaxies grow according to the evolution of the halo mass function, which we allow to vary with large-scale environment. Our model produces a reasonable match to the observed ultraviolet (UV) luminosity functions in this era by regulating star formation through stellar feedback and assuming that the UV luminosity function is dominated by recent star formation. We find that cosmic variance in the UV luminosity function is dominated by the variance in the underlying dark matter halo population, and not by differences in halo accretion or the specifics of our stellar feedback model. We also find that cosmic variance dominates over Poisson noise for future high-z surveys except for the brightest sources or at very high redshifts (z ≳ 12). We provide a linear approximation of cosmic variance for a variety of redshifts, magnitudes, and survey areas through the public python package galcv. Finally, we introduce a new method for incorporating priors on cosmic variance into estimates of the galaxy luminosity function and demonstrate that it significantly improves constraints on that important observable.

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