Roberto P. Muñoz

The next generation Virgo cluster survey. VI. the kinematics of ultra-compact dwarfs and globular clusters in m87

The origin of ultra-compact dwarfs (UCDs; r(h) greater than or similar to 10 pc)-objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies-has been hotly debated in the 15 years 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-* greater than or similar to 2x10(6) M-circle dot 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 similar to 70 kpc 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 less than or similar to 40 kpc and radially biased farther out, whereas blue GCs become more tangentially biased at larger radii beyond similar to 40 kpc; (4) GCs with M-* greater than or similar to 2 x 10(6) M-circle dot 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.

Larger sizes of massive quiescent early-type galaxies in clusters than in the field at 0.8 < z < 1.5

We analyse the mass–size relation of ∼400 quiescent massive ETGs (M_*/M_⊙ > 3 × 10^(10)) hosted by massive clusters (M_(200 ∼ 2–7) × 10^(14)M_⊙) at 0.8 < z < 1.5, compared to those found in the field at the same epoch. Size is parametrized using the mass-normalized B-band rest-frame size, γ=R_e/M^(0.57)_(11). We find that the γ distributions in both environments peak at the same position, but the distributions in clusters are more skewed towards larger sizes. This tail induces average sizes ∼30–40 peru2009cent larger for cluster galaxies than for field galaxies of similar stellar mass, while the median sizes are statistically the same with a difference of ∼10 ± 10 peru2009cent. Since this size difference is not observed in the local Universe, the evolution of average galaxy size at fixed stellar mass from z ∼ 1.5 for cluster galaxies is less steep at more than 3σ (∝(1 + z)^(−0.53 ± 0.04)) than the evolution of field galaxies (∝(1 + z)^(−0.92 ± 0.04)). The difference in evolution is not measured when the median values of γ are considered: ∝(1 + z)^(−0.84 ± 0.04) in the field versus ∝(1 + z)^(−0.71 ± 0.05) in clusters. In our sample, the tail of large galaxies is dominated by galaxies with 3 × 10^(10) < M_*/M_⊙ < 10^(11). At this low-mass end, the difference in the average size is better explained by the accretion of new galaxies that are quenched more efficiently in clusters and/or by different morphological mixing in the cluster and field environments. If part of the size evolution would be due to mergers, the difference that we see between cluster and field galaxies could be caused by higher merger rates in clusters at higher redshift, when galaxy velocities are lower.

UNVEILING A RICH SYSTEM OF FAINT DWARF GALAXIES IN THE NEXT GENERATION FORNAX SURVEY

We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded

The Next Generation Virgo Cluster Survey-Infrared (NGVS-IR). I. A New Near-Ultraviolet, Optical, and Near-Infrared Globular Cluster Selection Tool

u, g

The Next Generation Virgo Cluster Survey. V. Modeling the Dynamics of M87 with the Made-to-measure Method

and

THE NEXT GENERATION VIRGO CLUSTER SURVEY. X. PROPERTIES OF ULTRA-COMPACT DWARFS IN THE M87, M49, AND M60 REGIONS

i

THE NEXT GENERATION VIRGO CLUSTER SURVEY. XV. THE PHOTOMETRIC REDSHIFT ESTIMATION FOR BACKGROUND SOURCES

-band image obtained with the DECam wide-field camera mounted on the 4-meter Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the {it Next Generation Fornax Survey} (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii

The accelerated build-up of the red sequence in high-redshift galaxy clusters

0.1! !75%

Dark matter-baryons separation at the lowest mass scale: The bullet group

at luminosities brighter than

Abundance ratios and IMF slopes in the dwarf elliptical galaxy NGC 1396 with MUSE

M_i!simeq!-15.0