The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies

Saifollahi, Teymoor; Trujillo, Ignacio; Beasley, Michael A.; Peletier, Reynier F.; Knapen, J. H.

doi:10.1093/mnras/staa3016

Cited by 50 publications

(46 citation statements)

References 49 publications

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“…For KK 197 and KKs 58, the S N are 18.2 and 16.9, respectively (Fahrion et al 2020b), and for KKs 55 it is 17.9. These numbers are compatible with the specific frequencies of dwarf galaxies from the Local Group (Grebel 2016) and other nearby dwarf galaxies (Georgiev et al 2010;Harris et al 2013), as well as dwarf galaxies in clusters (Lim et al 2018;Prole et al 2019;Saifollahi et al 2020), but we note that the S N has a significant scatter in the classical dwarf galaxy regime.…”

Section: Globular Clusters Propertiessupporting

confidence: 86%

The properties of dwarf spheroidal galaxies in the Cen A group

Müller

Fahrion

Rejkuba

et al. 2021

A&A

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Dwarf spheroidal galaxies (dSphs) have been extensively investigated in the Local Group, but their low luminosity and surface brightness make similar work in more distant galaxy groups challenging. Modern instrumentation unlocks the possibility of scrutinizing these faint systems in other environments, expanding the parameter space of group properties. We use MUSE spectroscopy to study the properties of 14 known or suspected dSph satellites of Cen A. Twelve targets are confirmed to be group members based on their radial velocities. Two targets are background galaxies at ∼50 Mpc: KK 198 is a face-on spiral galaxy, and dw1315-45 is an ultradiffuse galaxy with an effective radius of ∼2300 pc. The 12 confirmed dSph members of the Cen A group have old and metal-poor stellar populations and follow the stellar metallicity-luminosity relation defined by the dwarf galaxies in the Local Group. In the three brightest dwarf galaxies (KK 197, KKs 55, and KKs 58), we identify globular clusters, as well as a planetary nebula in KK 197, although its association with this galaxy and/or the extended halo of Cen A is uncertain. Using four discrete tracers, we measure the velocity dispersion and dynamical mass of KK 197. This dSph appears dark matter dominated and lies on the radial acceleration relation of star-forming galaxies within the uncertainties. It also is consistent with predictions stemming from modified Newtonian dynamics (MOND). Surprisingly, in the dwarf KK 203 we find an extended Hα ring. Careful examination of Hubble Space Telescope photometry reveals a very low level of star formation at ages between 30-300 Myr. The Hα emission is most likely linked to a ∼40 Myr old supernova remnant, although other possibilities for its origin cannot be entirely ruled out.

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Section: Globular Clusters Propertiessupporting

confidence: 86%

The properties of dwarf spheroidal galaxies in the Cen A group

Müller

Fahrion

Rejkuba

et al. 2021

A&A

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“…Overall, it seems that UDGs show a wide range of GC abundances; some are GC−poor and some are GC−rich (Gannon et al 2021) In contrast to GC abundances, other GC properties appear to be similar in UDGs and non-UDGs. The ratio of the GC half-number radius (𝑅 GC ) to the UDG effective radius (𝑅 e ) of < 2, the GC colours (dominantly blue and metal-poor), and the shape of GC luminosity function (GCLF) are all similar to what is found for GCs in dwarf galaxies (Beasley & Trujillo 2016;Peng & Lim 2016;van Dokkum et al 2017;Amorisco et al 2018;Prole et al 2019;Lim et al 2020;Somalwar et al 2020;Saifollahi et al 2021;Müller et al 2021) These results suggest that GCs in UDGs are similar to those in other galaxies and that what differs between GCs in UDGs and other galaxies is simply the relative formation efficiency between them and the stars in the host galaxy. As such, GCs may provide an avenue for discriminating among competing UDG formation/evolution models.…”

Section: Introductionsupporting

confidence: 66%

“…Our large UDGs are expected to host a few tens of GCs each of which about half of that many are brighter than the GCLF turn-over magnitude (Peng & Lim 2016;Beasley & Trujillo 2016;Saifollahi et al 2021). Additionally, we are 75 per cent complete near the peak of the GCLF, and so expect a fraction (more than 75 per cent) of that half in our catalogues.…”

Section: Gc Luminosity Functionmentioning

confidence: 86%

Implications for Galaxy Formation Models from Observations of Globular Clusters around Ultra-Diffuse Galaxies

Saifollahi,

Zaritsky,

Trujillo

et al. 2022

Preprint

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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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“…This is the fraction of GC candidates per unit area within the 3×r e f f region divided by the number of candidates per unit area outside of this region. We used 3×r e f f as a value in which most of the GCs are expected to be located, if they exist, motivated by the works by Forbes (2017) and Saifollahi et al (2021). With this β parameter we take into account the size of each LSBG to obtain a possible overdensity of GC candidates on it.…”

Section: Potential Gcs In the Lsbgsmentioning

confidence: 99%

Discovery and analysis of low-surface-brightness galaxies in the environment of NGC 1052

Román

Castilla

Pascual-Granado

2021

A&A

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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 mag arcsec −2 , of which 20 are previously undetected objects. Among all the newly detected objects, RCP 32 stands out with extreme properties: r e f f = 23.0 arcsec and <µ g > e f f = 28.6 mag arcsec −2 . This makes RCP 32 one of the lowest surface brightness galaxies ever detected through integrated photometry, located at just 10 arcmin from the extensively studied NGC 1052-DF2. We explored the presence of globular clusters (GCs) in the LSBGs. We marginally detected a GC system in RCP 32, and argue that this LSBG is of great interest for follow-up observations given its extremely low baryon density. After analyzing the distribution of galaxies with available spectroscopy, we identified a large-scale structure of approximately 1 Mpc that is well isolated in redshift space and centered on NGC 1052. The spatial correlation analysis between the LSBGs and this large-scale structure suggests their association. However, when exploring the distribution of effective radius, we find an overpopulation of large LSBGs (r e f f > 15 arcsec) located close to the line of sight of NGC 1052. We argue that this is suggestive of a substructure with similar radial velocity in sight projection, but at a closer distance, to which some of these apparently larger LSBGs could be associated. However. possible effects derived from tidal interactions are worthy of further study. Our work expands the catalog of LSBGs with new interesting objects and provides a detailed environmental context for the study of LSBGs in this region.

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The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies

Cited by 50 publications

References 49 publications

The properties of dwarf spheroidal galaxies in the Cen A group

The properties of dwarf spheroidal galaxies in the Cen A group

Implications for Galaxy Formation Models from Observations of Globular Clusters around Ultra-Diffuse Galaxies

Discovery and analysis of low-surface-brightness galaxies in the environment of NGC 1052

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