scholarly journals Spectroscopic study of MATLAS-2019 with MUSE: An ultra-diffuse galaxy with an excess of old globular clusters

2020 ◽  
Vol 640 ◽  
pp. A106 ◽  
Author(s):  
Oliver Müller ◽  
Francine R. Marleau ◽  
Pierre-Alain Duc ◽  
Rebecca Habas ◽  
Jérémy Fensch ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Mass Scaling ◽  
Systematic Uncertainties ◽  
Deep Imaging ◽  
Systemic Velocity ◽  
The Galaxy ◽  
Stellar Body ◽  
The Individual ◽  
Field Unit

The MATLAS deep imaging survey has uncovered a plethora of dwarf galaxies in the low density environment it has mapped. A fraction of them are unusually extended and have low surface brightness. Among these so-called ultra-diffuse galaxies, a few seem to host an excess of globular clusters (GCs). With the integral field unit spectrograph MUSE we have observed one of these galaxies – MATLAS J15052031+0148447 (MATLAS-2019) – located toward the nearby group NGC 5846 and measured its systemic velocity, age, and metallicity, and that of its GC candidates. For the stellar body of MATLAS-2019 we derive a metallicity of −1.33−0.01+0.19 dex and an age of 11.2−0.8+1.8 Gyr. For some of the individual GCs and the stacked GC population, we derive consistent ages and metallicities. From the 11 confirmed GCs and using a Markov Chain Monte Carlo approach we derived a dynamical mass-to-light ratio of 4.2−3.4+8.6 M⊙/L⊙. This is at the lower end of the luminosity-mass scaling relation defined by the Local Group dwarf galaxies. Furthermore, we could not confirm or reject the possibility of a rotational component in the GC system. If present, this would further modify the inferred mass. Follow-up observations of the GC population and of the stellar body of the galaxy are needed to assess whether this galaxy lacks dark matter, as was suggested for the pair of dwarf galaxies in the field of NGC 1052, or if this is a misinterpretation arising from systematic uncertainties of the method commonly used for these systems and the large uncertainties of the individual GC velocities.

scholarly journals The Fornax 3D project: Globular clusters tracing kinematics and metallicities

2020 ◽  
Vol 637 ◽  
pp. A26 ◽  
Author(s):  
K. Fahrion ◽  
M. Lyubenova ◽  
M. Hilker ◽  
G. van de Ven ◽  
J. Falcón-Barroso ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Globular Clusters ◽  
Spectroscopic Studies ◽  
Host Galaxy ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Stellar Body ◽  
Galaxy Assembly ◽  
Fossil Records ◽  
Fornax Cluster

Globular clusters (GCs) are found ubiquitously in massive galaxies and due to their old ages, they are regarded as fossil records of galaxy evolution. Spectroscopic studies of GC systems are often limited to the outskirts of galaxies, where GCs stand out against the galaxy background and serve as bright tracers of galaxy assembly. In this work, we use the capabilities of the Multi Unit Explorer Spectrograph (MUSE) to extract a spectroscopic sample of 722 GCs in the inner regions (≲3 Reff) of 32 galaxies in the Fornax cluster. These galaxies were observed as part of the Fornax 3D project, a MUSE survey that targets early and late-type galaxies within the virial radius of Fornax. After accounting for the galaxy background in the GC spectra, we extracted line-of-sight velocities and determined metallicities of a sub-sample of 238 GCs. We found signatures of rotation within GC systems, and comparing the GC kinematics and that of the stellar body shows that the GCs trace the spheroid of the galaxies. While the red GCs prove to closely follow the metallicity profile of the host galaxy, the blue GCs show a large spread of metallicities but they are generally more metal-poor than the host.

scholarly journals Spatially Resolved Stellar Spectroscopy of the Ultra-diffuse Galaxy Dragonfly 44. III. Evidence for an Unexpected Star Formation History under Conventional Galaxy Evolution Processes

2022 ◽  
Vol 924 (1) ◽  
pp. 32
Author(s):  
Alexa Villaume ◽  
Aaron J. Romanowsky ◽  
Jean Brodie ◽  
Pieter van Dokkum ◽  
Charlie Conroy ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Globular Clusters ◽  
Stellar Population ◽  
Dwarf Galaxies ◽  
Star Formation History ◽  
Population Parameters ◽  
Spatially Resolved ◽  
Formation History ◽  
Field Unit

Abstract We use the Keck Cosmic Web Imager integral field unit spectrograph to (1) measure the global stellar population parameters for the ultra-diffuse galaxy (UDG) Dragonfly 44 (DF44) to much higher precision than previously possible for any UDG and (2) for the first time measure spatially resolved stellar population parameters of a UDG. We find that DF44 falls below the mass–metallicity relation established by canonical dwarf galaxies both in and beyond the Local Group. We measure a flat radial age gradient ( m logage = + 0.01 − 0.08 + 0.08 log Gyr kpc−1) and a flat to positive metallicity gradient ( m [ Fe / H ] = + 0.09 − 0.12 + 0.11 dex kpc−1), which are inconsistent with the gradients measured in similarly pressure-supported dwarf galaxies. We also measure a negative [Mg/Fe] gradient ( m [ Mg / Fe ] = − 0.20 − 0.18 + 0.18 ) dex kpc−1 such that the central 1.5 kpc of DF44 has stellar population parameters comparable to metal-poor globular clusters. Overall, DF44 does not have internal properties similar to other dwarf galaxies and is inconsistent with it having been puffed up through a prolonged, bursty star formation history, as suggested by some simulations. Rather, the evidence indicates that DF44 experienced an intense epoch of “inside-out” star formation and then quenched early and catastrophically, such that star formation was cut off more quickly than in canonical dwarf galaxies.

scholarly journals The Effect of Dwarf Galaxies on the Tidal Tails of Globular Clusters

2021 ◽  
Author(s):  
Nada El-Falou ◽  
Jeremy J Webb
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Size And Shape ◽  
The Galaxy ◽  
Galaxy Model ◽  
Galactic Globular Clusters ◽  
Tidal Tails

Abstract The tidal tails of globular clusters have been shown to be sensitive to the external tidal field. We investigate how Galactic globular clusters with observed tails are affected by satellite dwarf galaxies by simulating tails in galaxy models with and without dwarf galaxies. The simulations indicate that tidal tails can be subdivided into into three categories based on how they are affected by dwarf galaxies: 1) dwarf galaxies perturb the progenitor cluster’s orbit (NGC 4590, Pal 1, Pal 5), 2) dwarf galaxies perturb the progenitor cluster’s orbit and individual tail stars (NGC 362, NGC 1851, NGC 4147, NGC 5466, NGC 7492, Pal 14, Pal 15), and 3) dwarf galaxies negligibly affect tidal tails (NGC 288, NGC 5139, NGC 5904, Eridanus). Perturbations to a cluster’s orbit occur when dwarf galaxies pass within its orbit, altering the size and shape of the orbital and tail path. Direct interactions between one or more dwarf galaxies and tail stars lead to kinks and spurs, however we find that features are more difficult to observe in projection. We further find that the tails of Pal 5 are shorter in the galaxy model with dwarf galaxies as it is closer to apocentre, which results in the tails being compressed. Additional simulations reveal that differences between tidal tails in the two galaxy models are primarily due to the Large Magellanic Cloud. Understanding how dwarf galaxies affect tidal tails allows for tails to be used to map the distribution of matter in dwarf galaxies and the Milky Way.

scholarly journals Chemical evolution of star clusters

2010 ◽  
Vol 368 (1913) ◽  
pp. 801-828 ◽  
Author(s):  
Jacco Th. van Loon
Keyword(s):  
Dark Matter ◽  
Chemical Evolution ◽  
Gravitational Potential ◽  
Globular Clusters ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Star Clusters ◽  
Galactic Bulge ◽  
Potential Wells ◽  
The Galaxy

I discuss the chemical evolution of star clusters, with emphasis on old Galactic globular clusters (GCs), in relation to their formation histories. GCs are clearly formed in a complex fashion, under markedly different conditions from any younger clusters presently known. Those special conditions must be linked to the early formation epoch of the Galaxy and must not have occurred since. While a link to the formation of GCs in dwarf galaxies has been suggested, present-day dwarf galaxies are not representative of the gravitational potential wells within which the GCs formed. Instead, a formation deep within the proto-Galaxy or within dark-matter mini-haloes might be favoured. Not all GCs may have formed and evolved similarly. In particular, we may need to distinguish Galactic Halo from Galactic Bulge clusters.

Outlying Hα blobs in SDSS IV MaNGA

2018 ◽  
Vol 14 (S344) ◽  
pp. 265-266
Author(s):  
Omkar Bait ◽  
Yogesh Wadadekar ◽  
Sudhanshu Barway
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Continuum Emission ◽  
Host Galaxy ◽  
Deep Imaging ◽  
Sky Survey ◽  
Optical Continuum ◽  
Low Mass ◽  
Field Unit ◽  
Rule Out

AbstractWe have discovered a population of 29 outlying Hα emitters which appear like unresolved blobs in the DR14 data release of the SDSS IV MaNGA integral field unit survey. They do not have any underlying optical continuum emission in deep imaging from the DECam Legacy Survey or Beijing-Arizona Sky Survey. These blobs either lie away from the disc of the host galaxy in the MaNGA IFU and/or have velocities which are different from the velocity map of the host galaxy. Interestingly, all of them show photoionisation due to star formation. These galaxies have very high specific star formation rates compared to the known population of dwarf galaxies. However, their metallicities are consistent with or even lowerthan those of the local volume dwarfs. Thus, we can possibly rule out tidal dwarf galaxies. They could represent a new population of low mass and starbursting dwarf galaxies.

scholarly journals The building blocks of the Milky Way halo using APOGEE and Gaia or Is the Galaxy a typical galaxy?

2019 ◽  
Vol 14 (S351) ◽  
pp. 170-173 ◽  
Author(s):  
Ricardo P. Schiavon ◽  
J. Ted Mackereth ◽  
Joel Pfeffer ◽  
Rob A. Crain ◽  
Jo Bovy
Keyword(s):  
Numerical Simulations ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Stellar Populations ◽  
Building Blocks ◽  
Stellar Content ◽  
The Galaxy ◽  
Milky Way Halo

AbstractWe summarise recent results from analysis of APOGEE/Gaia data for stellar populations in the Galactic halo, disk, and bulge, leading to constraints on the contribution of dwarf galaxies and globular clusters to the stellar content of the Milky Way halo. Intepretation of the extant data in light of cosmological numerical simulations suggests that the Milky Way has been subject to an unusually intense accretion history at z ≳ 1.5.

scholarly journals A nuclear ionized gas outflow in the Seyfert 2 galaxy UGC 2024

2019 ◽  
Vol 487 (3) ◽  
pp. 3679-3692 ◽  
Author(s):  
Dania Muñoz-Vergara ◽  
Neil M Nagar ◽  
Venkatessh Ramakrishnan ◽  
Carolina Finlez ◽  
Thaisa Storchi-Bergmann ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Emission Lines ◽  
Ionized Gas ◽  
Full Field ◽  
North West ◽  
Gas Kinematics ◽  
Systemic Velocity ◽  
The Galaxy ◽  
Field Unit ◽  
Prime 2

ABSTRACT As part of a high-resolution observational study of feeding and feedback processes occurring in the vicinity of the active galactic nucleus in 40 galaxies, we observed the inner 3${^{\prime\prime}_{.}}$5 × 5 arcsec of the nearby spiral and Seyfert 2 galaxy UGC 2024 with the integral field unit of the Gemini-South Telescope. The observations enabled a study of the stellar and gas kinematics in this region at a spatial resolution of 0${^{\prime\prime}_{.}}$5 (218 pc), and a spectral resolution of 36  km s−1 over the wavelength range 4100–7300 Å. For the strongest emission-lines (H β, [$\rm{O\,{\small III}}$] λ5007 Å, H α, [$\rm{N\,{\small II}}$] λ6584 Å, and [$\rm{S\,{\small II}}$] λλ6717,6731 Å) we derived maps of the flux, radial velocity, and velocity dispersion. The flux distribution and kinematics of the [$\rm{O\,{\small III}}$] emission line are roughly symmetric around the nucleus: the radial velocity is close to systemic over the full field of view. The kinematics of the other strong emission lines trace both this systemic velocity component, and ordered rotation (with kinematic centre 0${^{\prime\prime}_{.}}$2 north-west of the nucleus). The stellar continuum morphology and kinematics are, however, asymmetrical around the nucleus. We interpret these unusual kinematics as the superposition of a component of gas rotating in the galaxy disc plus a ‘halo’ component of highly ionized gas. This halo either traces a quasi-spherical fountain with average radial velocity 200 km s−1, in which case the total nuclear outflow mass and momentum are 2 × 105 M⊙ and 4 × 107 M⊙ km s−1, respectively, or a dispersion supported halo created by a past nuclear starburst.

scholarly journals Imprints of mass accretion history on the shape of the intracluster medium and the TX–M relation

2019 ◽  
Vol 490 (2) ◽  
pp. 2380-2389 ◽  
Author(s):  
Huanqing Chen ◽  
Camille Avestruz ◽  
Andrey V Kravtsov ◽  
Erwin T Lau ◽  
Daisuke Nagai
Keyword(s):  
Galaxy Clusters ◽  
Bimodal Distribution ◽  
Characteristic Time Scale ◽  
Intracluster Medium ◽  
X Ray ◽  
Mass Scaling ◽  
Systematic Uncertainties ◽  
The Galaxy ◽  
Statistical Sample ◽  
The Impact

ABSTRACT We use a statistical sample of galaxy clusters from a large cosmological N-body + hydrodynamics simulation to examine the relation between morphology, or shape, of the X-ray emitting intracluster medium (ICM) and the mass accretion history of the galaxy clusters. We find that the mass accretion rate (MAR) of a cluster is correlated with the ellipticity of the ICM. The correlation is largely driven by material accreted in the last ∼4.5 Gyr, indicating a characteristic time-scale for relaxation of cluster gas. Furthermore, we find that the ellipticity of the outer regions (R ∼ R500c) of the ICM is correlated with the overall MAR of clusters, while ellipticity of the inner regions (≲0.5 R500c) is sensitive to recent major mergers with mass ratios of ≥1:3. Finally, we examine the impact of variations in cluster mass accretion history on the X-ray observable–mass scaling relations. We show that there is a continuous anticorrelation between the residuals in the TX–M relation and cluster MARs, within which merging and relaxed clusters occupy extremes of the distribution rather than form two peaks in a bimodal distribution, as was often assumed previously. Our results indicate that the systematic uncertainties in the X-ray observable–mass relations can be mitigated by using the information encoded in the apparent ICM ellipticity.

scholarly journals The Next Generation Fornax Survey (NGFS): VII. A MUSE view of the nuclear star clusters in Fornax dwarf galaxies

2020 ◽  
Vol 495 (2) ◽  
pp. 2247-2264
Author(s):  
Evelyn J Johnston ◽  
Thomas H Puzia ◽  
Giuseppe D’Ago ◽  
Paul Eigenthaler ◽  
Gaspar Galaz ◽  
...  
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Star Clusters ◽  
Stellar Populations ◽  
Host Galaxy ◽  
Wide Field ◽  
The Core ◽  
The Galaxy

ABSTRACT Clues to the formation and evolution of nuclear star clusters (NSCs) lie in their stellar populations. However, these structures are often very faint compared to their host galaxy, and spectroscopic analysis of NSCs is hampered by contamination of light from the rest of the system. With the introduction of wide-field integral field unit (IFU) spectrographs, new techniques have been developed to model the light from different components within galaxies, making it possible to cleanly extract the spectra of the NSCs and study their properties with minimal contamination from the light of the rest of the galaxy. This work presents the analysis of the NSCs in a sample of 12 dwarf galaxies in the Fornax Cluster observed with the Multi-Unit Spectroscopic Explorer (MUSE). Analysis of the stellar populations and star formation histories reveal that all the NSCs show evidence of multiple episodes of star formation, indicating that they have built up their mass further since their initial formation. The NSCs were found to have systematically lower metallicities than their host galaxies, which is consistent with a scenario for mass assembly through mergers with infalling globular clusters, whilst the presence of younger stellar populations and gas emission in the core of two galaxies is indicative of in-situ star formation. We conclude that the NSCs in these dwarf galaxies likely originated as globular clusters that migrated to the core of the galaxy that have built up their mass mainly through mergers with other infalling clusters, with gas-inflow leading to in-situ star formation playing a secondary role.

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