scholarly journals Scaling relations and the fundamental line of the local group dwarf galaxies

2008 ◽  
Author(s):  
Joanna Woo ◽  
Stéphane Courteau ◽  
Avishai Dekel
Keyword(s):  
Local Group ◽  
Dwarf Galaxies ◽  
Scaling Relations ◽  
Fundamental Line

An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750

2019 ◽  
Vol 15 (S356) ◽  
pp. 376-376
Author(s):  
Ingyin Zaw
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Host Galaxy ◽  
Scaling Relations ◽  
Host Galaxies ◽  
Seed Formation ◽  
Maser Emission ◽  
Water Masers

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.

Subaru Hyper Suprime-Cam Survey for the Local Group Dwarf Galaxies: Ursa Minor

2018 ◽  
Vol 14 (S344) ◽  
pp. 94-95
Author(s):  
Yutaka Komiyama
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Structural Parameters ◽  
Deep Imaging ◽  
Ursa Minor ◽  
Red Giant

AbstractWe have carried out a wide and deep imaging survey for the Local Group dwarf spheroidal galaxy Ursa Minor (UMi) using Hyper Suprime-Cam (HSC). The data cover out beyond the nominal tidal radius down to ~25 mag in i band, which is ~2 mag below the main sequence turn-off point. The structural parameters of UMi are derived using red giant branch (RGB) stars and sub-giant branch (SGB) stars, and the tidal radius is suggested to be larger than those estimated by the previous studies. It is also found that the distribution of bluer RGB/SGB stars is more extended than that of redder RGB/SGB stars. The fraction of binary systems is estimated to be ~0.4 from the morphology of the main sequences.

scholarly journals Feeding and feedback from little monsters: AGN in dwarf galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 238-242
Author(s):  
Mar Mezcua
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Early Universe ◽  
Dwarf Galaxies ◽  
Scaling Relations ◽  
Strong Impact ◽  
Hole Formation ◽  
Intermediate Mass ◽  
Black Hole Formation ◽  
Low Mass

AbstractDetecting the seed black holes from which quasars formed is extremely challenging; however, those seeds that did not grow into supermassive should be found as intermediate-mass black holes (IMBHs) of 100 – 105 M⊙ in local dwarf galaxies. The use of deep multiwavelength surveys has revealed that a population of actively accreting IMBHs (low-mass AGN) exists in dwarf galaxies at least out to z ˜3. The black hole occupation fraction of these galaxies suggests that the early Universe seed black holes formed from direct collapse of gas, which is reinforced by the possible flattening of the black hole-galaxy scaling relations at the low-mass end. This scenario is however challenged by the finding that AGN feedback can have a strong impact on dwarf galaxies, which implies that low-mass AGN in dwarf galaxies might not be the untouched relics of the early seed black holes. This has important implications for seed black hole formation models.

scholarly journals Pushing back the limits: detailed properties of dwarf galaxies in a ΛCDM universe

2018 ◽  
Vol 616 ◽  
pp. A96 ◽  
Author(s):  
Yves Revaz ◽  
Pascale Jablonka
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Mass Scale ◽  
Dwarf Spheroidal Galaxies ◽  
The Galaxy ◽  
Dynamical Simulations ◽  
Ursa Minor ◽  
Stellar Properties ◽  
Star Formation Histories

We present the results of a set of high-resolution chemo-dynamical simulations of dwarf galaxies in a ΛCDM cosmology. Out of an original (3.4 Mpc/h)3 cosmological box, a sample of 27 systems are re-simulated from z = 70 to z = 0 using a zoom-in technique. Gas and stellar properties are confronted to the observations in the greatest details: in addition to the galaxy global properties, we investigated the model galaxy velocity dispersion profiles, half-light radii, star formation histories, stellar metallicity distributions, and [Mg/Fe] abundance ratios. The formation and sustainability of the metallicity gradients and kinematically distinct stellar populations are also tackled. We show how the properties of six Local Group dwarf galaxies, NGC 6622, Andromeda II, Sculptor, Sextans, Ursa Minor and Draco are reproduced, and how they pertain to three main galaxy build-up modes. Our results indicate that the interaction with a massive central galaxy could be needed for a handful of Local Group dwarf spheroidal galaxies only, the vast majority of the systems and their variety of star formation histories arising naturally from a ΛCDM framework. We find that models fitting well the local Group dwarf galaxies are embedded in dark haloes of mass between 5 × 108 to a few 109 M⊙, without any missing satellite problem. We confirm the failure of the abundance matching approach at the mass scale of dwarf galaxies. Some of the observed faint however gas-rich galaxies with residual star formation, such as Leo T and Leo P, remain challenging. They point out the need of a better understanding of the UV-background heating.

Chemical composition of globular clusters in dwarf galaxies

2019 ◽  
Vol 14 (S351) ◽  
pp. 317-320
Author(s):  
Søren S. Larsen
Keyword(s):  
Chemical Composition ◽  
Globular Clusters ◽  
Milky Way ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Chemical Abundances ◽  
Preliminary Results ◽  
Detailed Chemical

AbstractThis contribution gives an update on on-going efforts to characterise the detailed chemical abundances of Local Group globular clusters (GCs) from integrated-light spectroscopy. Observations of a sample of 20 GCs so far, located primarily within dwarf galaxies, show that at low metallicities the [α/Fe] ratios are generally indistinguishable from those in Milky Way GCs. However, the “knee” above which [α/Fe] decreases towards Solar-scaled values occurs at lower metallicities in the dwarfs, implying that GCs follow the same trends seen in field stars. Efforts are underway to establish NLTE corrections for integrated-light abundance measurements, and preliminary results for Mn are discussed.

scholarly journals Dwarf Galaxies and the Black–Hole Scaling Relations

2020 ◽  
Author(s):  
Andrew King ◽  
Rebecca Nealon
Keyword(s):  
Black Hole ◽  
Dwarf Galaxies ◽  
Initial Distribution ◽  
Scaling Relations ◽  
Massive Galaxies ◽  
Stellar Feedback ◽  
Stellar Masses ◽  
Black Hole Masses ◽  
Close Fit ◽  
Fundamental Physical

Abstract The sample of dwarf galaxies with measured central black hole masses M and velocity dispersions σ has recently doubled, and gives a close fit to the extrapolation of the M∝σ relation for more massive galaxies. We argue that this is difficult to reconcile with suggestions that the scaling relations between galaxies and their central black holes are simply a statistical consequence of assembly through repeated mergers. This predicts black hole masses significantly larger than those observed in dwarf galaxies unless the initial distribution of uncorrelated seed black hole and stellar masses is confined to much smaller masses than earlier assumed. It also predicts a noticeable flattening of the M∝σ relation for dwarfs, to M∝σ2 compared with the observed M∝σ4. In contrast black hole feedback predicts that black hole masses tend towards a universal M∝σ4 relation in all galaxies, and correctly gives the properties of powerful outflows recently observed in dwarf galaxies. These considerations emphasize once again that the fundamental physical black-hole — galaxy scaling relation is between M and σ. The relation of M to the bulge mass Mb is acausal, and depends on the quite independent connection between Mb and σ set by stellar feedback.

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