APPROXIMATELY A THOUSAND ULTRA-DIFFUSE GALAXIES IN THE COMA CLUSTER

By J. Koda, M. Yagi, H. Yamanoi, Y. Komiyama. 2015

190 citations recorded by the source corpus.

We report the discovery of 854 ultra-diffuse galaxies (UDGs) in the Coma cluster using deep R band images, with partial B, i, and Hα band coverage, obtained with the Subaru telescope. Many of them (332) are Milky Way (MW) sized with very large effective radii of r e > 1.5 kpc ?> . This study was motivated by the recent discovery of 47 UDGs by Dokkum et al.; our discovery suggests > 1000 ?> UDGs after accounting for the smaller Subaru field ( 4.1 degree 2 ?> ; about one-half of Dragonfly). The new Subaru UDGs show a distribution concentrated around the cluster center, strongly suggesting that the great majority are (likely longtime) cluster members. They are a passively evolving population, lying along the red sequence in the color–magnitude diagram with no signature of Hα emission. Star formation was, therefore, quenched in the past. They have exponential light profiles, effective radii r e ∼ 800 pc ?> – 5 kpc ?> , effective surface brightnesses &mgr; e ( R ) = ?> 25–28 mag arcsec−2, and stellar masses ∼ 1 × 10 7 M ⊙ ?> – 5 × 10 8 M ⊙ ?> . There is also a population of nucleated UDGs. Some MW-sized UDGs appear closer to the cluster center than previously reported; their survival in the strong tidal field, despite their large sizes, possibly indicates a large dark matter fraction protecting the diffuse stellar component. The indicated baryon fraction ≲ 1 % ?> is less than the cosmic average, and thus the gas must have been removed (from the possibly massive dark halo). The UDG population is elevated in the Coma cluster compared to the field, indicating that the gas removal mechanism is related primarily to the cluster environment.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e7c4e2f6a1ccaff9afb365eaff918d5cbab2fbbe

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Citations in the corpus

Ultra-diffuse galaxies outside clusters: clues to their formation and evolution (2016, methodology): “For this reason, these galaxies have been explored in galaxy clusters, where the distance to the UDGs is inferred by their proximity to the massive structure (e.g. Koda et al. 2015; Mihos et al. 2015; Muñoz et al. 2015; van der Burg et al. 2016).”
Ultradiffuse galaxies: the high-spin tail of the abundant dwarf galaxy population (2016, background): “…also in the Virgo cluster (Mihos et al. 2015), the Fornax cluster (Muñoz et al. 2015), in 8 other clusters at redshift z = 0.044 − 0.063 (van der Burg et al. 2016, vdB16), and the number of detections in Coma have increased by at least an order of magnitude (Koda et al. 2015, K15).”
GALAXIES AT THE EXTREMES: ULTRA-DIFFUSE GALAXIES IN THE VIRGO CLUSTER (2015, background): “The derived properties given in Table 1 show that, like the extreme Coma LSBs (vD15a, Koda et al. 2015; K15), these objects are reasonably well characterized by exponential profiles (n ∼ 1.0).”
Gravitational probes of dark matter physics (2017, background): “A new class of ultradiffuse (extremely low projected luminosity density) galaxies has been discovered, largely in galaxy clusters (because that is where people looked first [549, 550, 551, 552, 553, 128, 554]), but also in the field [555, 556, 557].”
NIHAO - XI. Formation of ultra-diffuse galaxies by outflows (2016, methodology): “Almost 1000 UDGs have been identified in the Coma cluster using the Dragonfly array (van Dokkum et al. 2015a,b) and the Subaru telescope (Koda et al. 2015; Yagi et al. 2016): they represent a passively evolving population, lying on the red sequence in the color-magnitude diagram, as opposed to…”
A HIGH STELLAR VELOCITY DISPERSION AND ∼100 GLOBULAR CLUSTERS FOR THE ULTRA-DIFFUSE GALAXY DRAGONFLY 44 (2016, background): “…examples of such galaxies had been known for many years (Impey, Bothun, & Malin 1988; Dalcanton et al. 1997), but their ubiquity, at least in dense environments (van Dokkum et al. 2015a; Koda et al. 2015; van der Burg, Muzzin, & Hoekstra 2016; Roman & Trujillo 2016), had not been recognized.”
(Almost) Dark Galaxies in the ALFALFA Survey: Isolated H i-bearing Ultra-diffuse Galaxies (2017, background): “UDGs appear to be common in cluster environments (e.g., Koda et al. 2015; van der Burg et al. 2016), and have colors and morphologies consistent with extrapolation of early type galaxies on the red sequence (van Dokkum et al. 2015).”
CATALOG OF ULTRA-DIFFUSE GALAXIES IN THE COMA CLUSTERS FROM SUBARU IMAGING DATA (2016, methodology): “Koda et al. (2015) reported 854 Subaru-UDGs in the archival Subaru data.”
Illuminating Low Surface Brightness Galaxies with the Hyper Suprime-Cam Survey (2017, background): “Blends of faint galaxies and/or distant galaxy groups are a major source of contamination for any deep diffuse-galaxy search (e.g., Koda et al. 2015; Sifón et al. 2018).”