Abstract:The environment of NGC 1052 has recently attracted much attention because of the presence of low-surface-brightness galaxies (LSBGs) with apparently "exotic" properties, making it a region of high interest for the detection of new objects. We used public deep photometric data from the Dark Energy Camera Legacy Survey to carry out a comprehensive search for LSBGs over a wide region of 6×6 degrees, equivalent to 2×2 Mpc at the distance of NGC 1052. We detected 42 LSBGs with r e f f > 5 arcsec and µ g (0) > 24 ma… Show more
“…4b . The unusual prevalence of large, low-surface-brightness galaxies in the central regions of the NGC 1052 group has been noted previously 1 , 23 ; here we propose that the bullet-dwarf event was responsible for it. Fig.…”
Section: Mainsupporting
confidence: 77%
“…The spatial distribution of galaxies with magnitude g > 16.5 in a recently compiled catalogue of the NGC 1052 field 23 is shown in Fig. 2a .…”
Section: Mainmentioning
confidence: 99%
“… a , Distribution of galaxies with g > 16.5 (black circles) from a recent compilation of low-surface-brightness objects in the NGC 1052 field 23 . The positions are with respect to the coordinates of NGC 1052, the central bright elliptical galaxy in the group.…”
Section: Mainmentioning
confidence: 99%
“…RCP 32 and DF7 are candidates for the two dark-matter-dominated remnants that have been predicted to precede dark-matter-deficient galaxies along the post-collision trajectory 11 . We also highlight DF9 (SDSS J024007.01−081344.4), a galaxy with a bright star cluster that falls on the trail but is not part of the objectively selected sample 23 . Fig.…”
The ultra-diffuse galaxies DF2 and DF4 in the NGC 1052 group share several unusual properties: they both have large sizes1, rich populations of overluminous and large globular clusters2–6, and very low velocity dispersions that indicate little or no dark matter7–10. It has been suggested that these galaxies were formed in the aftermath of high-velocity collisions of gas-rich galaxies11–13, events that resemble the collision that created the bullet cluster14 but on much smaller scales. The gas separates from the dark matter in the collision and subsequent star formation leads to the formation of one or more dark-matter-free galaxies12. Here we show that the present-day line-of-sight distances and radial velocities of DF2 and DF4 are consistent with their joint formation in the aftermath of a single bullet-dwarf collision, around eight billion years ago. Moreover, we find that DF2 and DF4 are part of an apparent linear substructure of seven to eleven large, low-luminosity objects. We propose that these all originated in the same event, forming a trail of dark-matter-free galaxies that is roughly more than two megaparsecs long and angled 7° ± 2° from the line of sight. We also tentatively identify the highly dark-matter-dominated remnants of the two progenitor galaxies that are expected11 at the leading edges of the trail.
“…4b . The unusual prevalence of large, low-surface-brightness galaxies in the central regions of the NGC 1052 group has been noted previously 1 , 23 ; here we propose that the bullet-dwarf event was responsible for it. Fig.…”
Section: Mainsupporting
confidence: 77%
“…The spatial distribution of galaxies with magnitude g > 16.5 in a recently compiled catalogue of the NGC 1052 field 23 is shown in Fig. 2a .…”
Section: Mainmentioning
confidence: 99%
“… a , Distribution of galaxies with g > 16.5 (black circles) from a recent compilation of low-surface-brightness objects in the NGC 1052 field 23 . The positions are with respect to the coordinates of NGC 1052, the central bright elliptical galaxy in the group.…”
Section: Mainmentioning
confidence: 99%
“…RCP 32 and DF7 are candidates for the two dark-matter-dominated remnants that have been predicted to precede dark-matter-deficient galaxies along the post-collision trajectory 11 . We also highlight DF9 (SDSS J024007.01−081344.4), a galaxy with a bright star cluster that falls on the trail but is not part of the objectively selected sample 23 . Fig.…”
The ultra-diffuse galaxies DF2 and DF4 in the NGC 1052 group share several unusual properties: they both have large sizes1, rich populations of overluminous and large globular clusters2–6, and very low velocity dispersions that indicate little or no dark matter7–10. It has been suggested that these galaxies were formed in the aftermath of high-velocity collisions of gas-rich galaxies11–13, events that resemble the collision that created the bullet cluster14 but on much smaller scales. The gas separates from the dark matter in the collision and subsequent star formation leads to the formation of one or more dark-matter-free galaxies12. Here we show that the present-day line-of-sight distances and radial velocities of DF2 and DF4 are consistent with their joint formation in the aftermath of a single bullet-dwarf collision, around eight billion years ago. Moreover, we find that DF2 and DF4 are part of an apparent linear substructure of seven to eleven large, low-luminosity objects. We propose that these all originated in the same event, forming a trail of dark-matter-free galaxies that is roughly more than two megaparsecs long and angled 7° ± 2° from the line of sight. We also tentatively identify the highly dark-matter-dominated remnants of the two progenitor galaxies that are expected11 at the leading edges of the trail.
“…• Another environment-motivated class of model, the "tidal interaction" scenario, has UDGs suffering dynamical heating within galaxy clusters and galaxy groups that "puffs" them up (e.g., Carleton et al 2019;Amorisco 2019;Sales et al 2020). Studies exist that both favour (Mancera Piña et al 2019;Rong et al 2020;Jones et al 2021;Román et al 2021) or disfavour (Venhola et al 2017;Kado-Fong et al 2021) this scenario. In such a scenario, the galaxy's low surface brightness is attributed to the dynamical expansion of the galaxy, not to a lower star formation efficiency, and so 𝑁 GC /𝑀 * should be comparable to that of dwarf galaxies.…”
We present an analysis of Hubble Space Telescope observations of globular clusters (GCs) in six ultra-diffuse galaxies (UDGs) in the Coma cluster, a sample that represents UDGs with large effective radii (𝑅 e ), and use the results to evaluate competing formation models. We eliminate two significant sources of systematic uncertainty in the determination of the number of GCs, 𝑁 GC by using sufficiently deep observations that (i) reach the turnover of the GC luminosity function and (ii) provide a sufficient number of GCs with which to measure the GC number radial distribution. We find that 𝑁 GC for these galaxies is on average ∼ 20, which implies an average total mass, 𝑀 total , ∼ 10 11 𝑀 when applying the relation between 𝑁 GC and 𝑀 total . This value of 𝑁 GC lies at the upper end of the range observed for dwarf galaxies of the same stellar mass and is roughly a factor of two larger than the mean. The GC luminosity function, radial profile and average colour are more consistent with those observed for dwarf galaxies than with those observed for the more massive (𝐿 * ) galaxies, while both the radial and azimuthal GC distributions closely follow those of the stars in the host galaxy. Finally, we discuss why our observations, specifically the GC number and GC distribution around these six UDGs, pose challenges for several of the currently favoured UDG formation models.
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