The Local Tully–fisher Relation for Dwarf Galaxies

Abstract

We study different incarnations of the Tully-Fisher (TF) relation for the Local Volume (LV) galaxies taken from Updated Nearby Galaxy Catalog. The UNGC sample contains 656 galaxies with W 50 HI-line-width estimates, mostly belonging to low mass dwarfs. Of them, 296 objects have distances measured with accuracy better than 10%. For the sample of 331 LV galaxies having baryonic masses log M bar > 5.8 log M ⊙ we obtain a relation log M bar = 2.49 log W 50 + 3.97 with observed scatter of 0.38 dex. The largest factors affecting the scatter are observational errors in K-band magnitudes and W 50 line widths for the tiny dwarfs, as well as uncertainty of their inclinations. We find that accounting for the surface brightness of the LV galaxies, or their gas fraction, or specific star formation rate, or the isolation index do not reduce essentially the observed scatter on the baryonic TF-diagram. We also notice that a sample of 71 dSph satellites of the Milky Way and M31 with known stellar velocity dispersion σ * tends to follow nearly the same bTF relation, having slightly lower masses than that of late-type dwarfs.

Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters

“…Using simulations, Pfeffer et al (2014) predicted the number of UCDs from stripped NSCs of a given stellar mass as a function of environment virial mass. For the Centaurus group, virial masses between 4.0 ×10 12 and 1.4 ×10 13 M are discussed (Karachentsev et al 2007;Woodley 2006;Woodley et al 2007Woodley et al , 2010 and due to this large scatter, the number of predicted UCDs from stripped NSCs with masses > 10 5 M ranges between ∼ 4 -13, following the prescription of Pfeffer et al (2014). Because these predictions strongly depend on the nucleation fraction of galaxies, assessing the number and masses of dwarf galaxy NSCs can help to improve such models.…”

Structure and kinematics of the Virgo cluster of galaxies

“…The basic observational characteristics of 1537 galaxies in the considered area are presented in Table 1, with the full machine readable version available at SIMBAD Astronomical Database 1 . The table columns contain the (1) galaxy name; (2) equatorial coordinates J2000.0; (3, 4) supergalactic coordinates; (5) projected distance of a galaxy from M87; (6) radial velocity (km s −1 ) relative to the Local Group centroid; (7) morphological type determined by us based on images from Sloan Digital Sky Survey (SDSS, Abazajian et al 2009) and Panoramic Survey Telescope and Rapid Response System (PanSTARRS, Chambers et al 2016); (8) apparent B-magnitude from Hy-perLEDA 2 (Makarov et al 2014) or NASA Extragalactic Database 3 (NED); (9) apparent K-magnitude calculated from B-magnitude adjusted for the morphological type of the galaxy according to Jarrett et al (2003); (10) 21 cm HI line width (km s −1 ) at half maximum from HyperLEDA data; (11) apparent HI-magnitude from Hy-perLEDA; (12, 13) distance modulus and galaxy distance (Mpc), (14) method applied to determine distance: 'cep', 'SN'-from supernovae and cepheids luminosity, 'sbf'-from surface brightness fluctuation, 'rgb'-from the tip of the red giant branch, 'bs'-from the brightest stars luminosity, 'FP'-from the fundamental plane, 'gc'-from luminosity function of globular clusters, 'tf', 'TF', 'TFb'-from Tully & Fisher relation (1977), with lowercase indicating distance estimates from NED, and uppercase indicating our estimates based on classical (Tully & Pierce 2000) or baryonic (Karachentsev et al 2017) Tully-Fisher relation.…”

The dwarf galaxy satellite system of Centaurus A

“…Our Cen A analogs were selected to be the primaries of halos within a mass range of 4.0 × 10 12 ≤ M 200 ≤ 1.2 × 10 13 (Karachentsev et al 2007;Woodley 2006;Woodley et al 2007Woodley et al , 2010, where M 200 is the total mass within a sphere that has a mean density of 200 times the critical density of the Universe. To ensure a comparable isolation to Cen A, all hosts that have another halo with M 200 ≥ 0.5 × 10 12 within a distance of 1.4 Mpc were discarded (representing the separation between Cen A and M 83).…”