Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Fahrion, Katja; Georgiev, Iskren Y.; Hilker, M.; Lyubenova, M.; Ven, Glenn van de; Alfaro-Cuello, Mayte; Corsini, E. M.; Sarzi, Marc; McDermid, Richard M.; Zeeuw, Tim de

doi:10.1051/0004-6361/201834941

Cited by 22 publications

(22 citation statements)

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“…The simultaneous extraction of the metallicity of both the NSC and the galaxy stellar body showed that these NSCs are more metal-poor than their hosts, suggesting that they have formed through the process of in-spiraling GCs. Intriguingly, the masses, sizes, and metallicities of these two NSCs are consistent with the properties of known ultra-compact dwarfs (Misgeld & Hilker 2011;Voggel et al 2018Voggel et al , 2020Fahrion et al 2019a), suggesting that stripped nuclei of dwarf galaxies are the progenitors of low-mass ultra-compact dwarfs (Strader et al 2013).…”

Section: )?supporting

confidence: 79%

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: )?supporting

confidence: 79%

The properties of dwarf spheroidal galaxies in the Cen A group

Müller

Fahrion

Rejkuba

et al. 2021

A&A

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“…Being a ETG in the outskirts of the Fornax cluster, the wealth of complexity in this galaxy has been surprising: we found two KDCs, a sharp central metallicity peak and FCC 47-UCD1. As we argue in Fahrion et al (2019), the UCD could be the stripped nucleus of a disrupted dwarf galaxy and would therefore indicate a minor merger in FCC 47's past. In addition, the KDCs most likely are evidence of at least one major merger event that has altered the kinematic structure of the galaxy significantly.…”

Section: Discussionmentioning

confidence: 73%

Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC 47

Fahrion

Lyubenova

Ven

et al. 2019

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Context. Nuclear star clusters (NSCs) are found in at least 70% of all galaxies, but their formation path is still unclear. In the most common scenarios, NSCs form in-situ from the galaxy's central gas reservoir, through merging of globular clusters (GCs), or through a combination of the two. Aims. As the scenarios pose different expectations for angular momentum and stellar population properties of the NSC in comparison to the host galaxy and the GC system, it is necessary to characterise the stellar light, NSC and GCs simultaneously. The large NSC (r eff = 66 pc) and rich GC system of the early-type Fornax cluster galaxy FCC 47 (NGC 1336) render this galaxy an ideal laboratory to constrain NSC formation. Methods. Using MUSE science verification data assisted by adaptive optics, we obtained maps for the stellar kinematics and for stellar-population properties of FCC 47. We extracted the spectra of the central NSC and determined line-of-sight velocities of 24 GCs and metallicities of five. Results. FCC 47 shows two decoupled components (KDCs): a rotating disk and the NSC. Our orbit-based dynamical Schwarzschild model revealed that the NSC is a distinct kinematic feature and it constitutes the peak of metallicity and old ages in the galaxy. The main body consists of two counter-rotating populations and is dominated by a more metal-poor population. The GC system is bimodal with a dominant metal-poor population and the total GC system mass is ∼ 17% of the NSC mass (∼ 7 × 10 8 M ). Conclusions. The rotation, high metallicity and high mass of the NSC cannot be uniquely explained by GC-inspiral and most likely requires additional, but quickly quenched, in-situ formation. The presence of two KDCs most probably are evidence of a major merger that has altered the structure of FCC 47 significantly, indicating the important role of galaxy mergers in forming the complex kinematics in the galaxy-NSC system.

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“…Further evidence that our 3 UCDs are the remnants of stripped galaxies comes from their physical sizes, which are all over 30 pc. Size was also used recently by Fahrion et al (2019) to support the stripped nucleus origin for a UCD they observed in the Fornax cluster. Using MUSE on the VLT, they measured an old age (> 8 Gyr) and low metallicity ([Z/H] = -1.12).…”

Section: Discussionmentioning

confidence: 99%

Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87

Forbes

Ferré-Mateu

Durré

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Abstract Using the Keck Cosmic Web Imager we obtain spectra of several globular clusters (GCs), ultra compact dwarfs (UCDs) and the inner halo starlight of M87, at a similar projected galactocentric radius of ∼5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs and starlight consistently to derive ages, metallicities and alpha-element abundances in M87. We find evidence for a dual stellar population in the M87 halo light, i.e an ∼80% component by mass which is old and metal-rich and a ∼20% component which is old but metal-poor. Two red GCs share similar stellar populations to the halo light suggesting they may have formed contemporaneously with the dominant halo component. Three UCDs, and one blue GC, have similar stellar populations, with younger mean ages, lower metallicities and near solar alpha-element abundances. Combined with literature data, our findings are consistent with the scenario that UCDs are the remnant nucleus of a stripped galaxy. We further investigate the discrepancy in the literature for M87’s kinematics at large radii, favouring a declining velocity dispersion profile. This work has highlighted the need for more self-consistent studies of galaxy halos.

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Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

Cited by 22 publications

References 142 publications

The properties of dwarf spheroidal galaxies in the Cen A group

The properties of dwarf spheroidal galaxies in the Cen A group

Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC 47

Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87

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