J/A+AS/130/341 Groups of Galaxies in PPS (Trasarti-Battistoni 1998)
Loose Groups of Galaxies in the Perseus-Pisces Survey
Trasarti-Battistoni R.
<Astron. Astrophys. Suppl. Ser. 130, 341 (1998)>
=1998A&AS..130..341T 1998A&AS..130..341T (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Velocity dispersion
Keywords: catalogs - Galaxies: cluster of ; luminosity function -
Cosmology: Large Scale Structure of the Universe.
Abstract:
We present a large catalog of galaxy loose groups in the Southern
Galactic Hemisphere, selected from the Perseus-Pisces redshift Survey
(PPS). Particular care is taken in order to obtain group samples as
homogeneous as possible to previously published catalogs. Groups are
identified with the adaptive Friends-of-Friends (FoF) algorithm of
Huchra & Geller (1982ApJ...257..423H 1982ApJ...257..423H), with suitable normalizations
V0=350km/s and D0=0.231h.Mpc. As a necessary ingredient of FoF
algorithms, we obtain the galaxy luminosity function (LF) for PPS. Its
Schechter parameters (α=-1.15±0.15, M*=-19.3±0.1) are in
good agreement with similar LF estimates from samples previously used
to select groups. The LF normalizations φ*=0.02h3/Mpc3
appropriate for PPS yields a density threshold δn/n∼180 for the
adopted D0, apparently rather different from the desired
δn/n∼80 used in previous studies. We then consider several other
link normalizations, and briefly discuss their effect on group
properties. We suggest to replace the customarily adopted δn/n
parametrization with the more direct D0 parametrization. All our
catalogs contain NG∼200 groups, significantly more than in most
previous studies where group samples were obtained from galaxy data
sets of comparable quality to (but smaller extent than) PPS. The group
properties are rather sensitive to the adopted D0 and V0, but vary
little with different redshift corrections, redshift cut-off, and
galaxy LF. Loose groups in PPS nicely trace the large scale structure
(LSS) in the parent galaxy sample. Physical properties of groups in
PPS and in other directly comparable samples are in good agreement.
There seems to be a complex interplay among LSS features, FoF grouping
procedure, and group properties.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 188 List of the values of group parameters for
D0=0.231Mpc/h and V0=350km/s
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See also:
J/AJ/105/1251 : Pisces-Perseus supercluster. V. (Wenger+, 1993)
J/AJ/105/1271 : Pisces-Perseus supercluster. VI (Giovanelli+, 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification of group
5- 7 I3 --- Nmemb Number of members
9- 11 I3 h RAh Mean right ascension 1950 (1)
13- 16 F4.1 min RAm Mean right ascension 1950 (1)
18 A1 --- DE- Sign declination (always blank)
19- 20 I2 deg DEd Mean declination 1950
22- 25 F4.1 arcmin DEm Mean declination 1950
27- 31 I5 km/s cz Mean redshift of members
33- 36 I4 km/s sigma Velocity dispersion
38- 41 F4.2 Mpc Rp Mean pairwise separation of members (2)
43- 46 F4.2 Mpc Rh Mean harmonic (virial) radius (2)
48- 52 F5.2 [solLum] log(L) Log of total luminosity (2) (3)
54- 58 F5.2 [solMass] log(M) Log of virial mass (2)
60- 64 F5.2 [Sun] log(M/L) Log of mass-to-light ratio (2) (3)
66- 70 F5.3 Mpc.s/km t(cr) Crossing time (2) (4)
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Note (1): RA was originally assigned values in the interval
[-1:30.0, +3:00.0], but without any value in the range
[0, -1]. There was clearly an omission of the minus sign in
that range, and the negative RA values were turned to standard
RA values. but it is not clear whether group #54 is 23:59.9
or 00:00.1 (mail exchange with the author, July 1998)
Note (2): Assuming h=1.0, i.e. Hubble constant H_0=100km/s/Mpc
Note (3): Observed luminosity, not corrected for the missed faint
member galaxies
Note (4): Defined as (2Rp)/(sqrt(3)sigma)
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Acknowledgements:
Roberto Trasarti-Battistoni
(End) Francois Ochsenbein, Patricia Bauer [CDS] 20-Aug-1998