J/AJ/147/13 Disturbers of nearby giant galaxies (Karachentsev+, 2014)
Suites of dwarfs around nearby giant galaxies.
Karachentsev I.D., Kaisina E.I., Makarov D.I.
<Astron. J., 147, 13 (2014)>
=2014AJ....147...13K 2014AJ....147...13K
ADC_Keywords: Galaxies, nearby
Keywords: galaxies: dwarf - galaxies: groups: general - galaxies: interactions
Abstract:
The Updated Nearby Galaxy Catalog (UNGC) contains the most
comprehensive summary of distances, radial velocities, and
luminosities for 800 galaxies located within 11Mpc from us. The high
density of observables in the UNGC makes this sample indispensable for
checking results of N-body simulations of cosmic structures on a ∼1Mpc
scale. The environment of each galaxy in the UNGC was characterized by
a tidal index Θ1, depending on the separation and mass of the
galaxy's main disturber (MD). We grouped UNGC galaxies with a common
MD in suites, and ranked suite members according to their Θ1.
All suite members with positive Θ1 are assumed to be physical
companions of the MD. About 58% of the sample are members of physical
groups. The distribution of suites by the number of members, n,
follows a relation N(n)∼n-2. The 20 most populated suites contain
468 galaxies, i.e., 59% of the UNGC sample. The fraction of MDs among
the brightest galaxies is almost 100% and drops to 50% at MB=-18m.
We discuss various properties of MDs, as well as galaxies belonging to
their suites. The suite abundance practically does not depend on the
morphological type, linear diameter, or hydrogen mass of the MD, the
tightest correlation being with the MD dynamical mass. Dwarf galaxies
around MDs exhibit well-known segregation effects: the population of
the outskirts has later morphological types, richer HI contents, and
higher rates of star formation activity. Nevertheless, there are some
intriguing cases where dwarf spheroidal galaxies occur at the far
periphery of the suites, as well as some late-type dwarfs residing
close to MDs. Comparing simulation results with galaxy groups, most
studies assume the Local Group is fairly typical. However, we
recognize that the nearby groups significantly differ from each other
and there is considerable variation in their properties. The suites of
companions around the Milky Way and M31, consisting of the Local
Group, do not quite seem to be a typical nearby group. The
multiplicity of nearby groups of the number of their physical members
can be described by the Hirsh-like index hg=9, indicating that the
Local Volume contains nine groups with populations exceeding nine
companions to their MDs.
Description:
The Updated Nearby Galaxy Catalog (UNGC; Karachentsev et al., 2013,
cat. J/AJ/145/101) contains the most complete summary of various
observable characteristics for 869 galaxies located within 11Mpc. The
environment of each galaxy in the UNGC was characterized by a tidal
index Θ1, depending on the separation and mass of the galaxy's
main disturber (MD). For each of the 869 galaxies in the UNGC, we
determined Θ1. We grouped UNGC galaxies with a common MD in
suites, and ranked suite members according to their Θ1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 796 Local Volume (LV) galaxies ranked according to
their main disturbers and tidal indices
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See also:
J/AJ/145/101 : Updated nearby galaxy catalog (Karachentsev+, 2013)
J/ApJ/676/184 : Peculiar motion away from the Local Void (Tully+, 2008)
J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)
http://www.sao.ru/lv/lvgdb : Database on the Local Volume Galaxies
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Galaxy name in well-known catalogs
19- 23 F5.2 kpc a26 ? Galaxy linear diameter (1)
25- 29 F5.1 mag BMag ? Absolute B-band magnitude (2)
31- 35 F5.2 [Msun] logM* ? Galaxy log stellar mass
37- 41 F5.2 [Msun] logM26 ? Galaxy log dynamic mass (3)
43 A1 --- l_logMHI [<] Upper limit flag on logMHI
44- 48 F5.2 [Msun] logMHI ? Galaxy log of the hydrogen mass
50- 53 F4.1 --- Ti1 [-2.4/6.6] Tidal index Θ1 (4)
55- 69 A15 --- MD Main disturber's name
71- 75 F5.2 Mpc D [0.01/11] Distance to the galaxy
77- 80 I4 km/s Dv ? Line-of-sight velocity Δv of the galaxy
relative to the velocity of the main disturber
82- 83 I2 --- Nm [1/53] Number of members in the suite of the
main disturber to which the galaxy belongs
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Note (1): Determined at Holmberg's isophote (26.5mag/arcsec2).
Note (2): Corrected for the Galactic and internal extinction.
Note (3): Within the Holmberg diameter:
log(M26)=2log(Vm)+log(a26)+log(D)+4.52,
where the rotation velocity Vm is expressed in km/s, the Holmberg
diameter a26 in angular minutes, and the distance D in Mpc.
Note (4): The tidal index is defined as in Karachentsev & Makarov
(1999IAUS..186..109K 1999IAUS..186..109K): Θ1=max[log(Ln/Dn3)]+C, n=1,2,...N
(where Ln is the K-band luminosity of the neighboring galaxy,
Dn is its spatial separation from the considered galaxy,
and the constant C=-10.96; see Sec.2 for details).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 27-Aug-2014