J/ApJ/440/28 Brightest Cluster Galaxies velocities (Postman+ 1995)
Brightest cluster galaxies as standard candles.
Postman M., Lauer T.R
<Astrophys. J. 440, 28 (1995)>
=1995ApJ...440...28P 1995ApJ...440...28P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Magnitudes ; Radial velocities
Keywords: galaxies: clusters: general - galaxies: photometry
Abstract:
We investigate the use of Brightest Cluster Galaxies (BCGs) as
standard candles for measuring galaxy peculiar velocities on large
scales. We have obtained precise large-format CCD surface photometry
and redshifts for an all-sky, volume-limited (z≤0.05) sample of 119
BCG. We reinvestigate the Hoessel (1980ApJ...241..493H 1980ApJ...241..493H) relationship
between the metric luminosity, Lm, within the central 10h-1kpc of
the BCGs and the logarithmic slope of the surface brightness profile,
α. The Lm-α relationship reduces the cosmic scatter in
Lm from 0.327mag to 0.244mag, yielding a typical distance accuracy
of 17% per BCG. Residuals about the Lm-α relationship are
independent of BCG luminosity, BCG B-Rc color, BCG location within
the host cluster, and richness of the host cluster. The metric
luminosity is independent of cluster richness even before correcting
for its dependence on α, which provides further evidence for the
unique nature of the BCG luminosity function. Indeed, the BCG
luminosity function, both before and after application of the
α-correction, is consistent with a single Gaussian distribution.
Half the BCGs in the sample show some evidence of small color
gradients as a function of radius within their central 50h-1kpc
regions but with almost equal numbers becoming redder as becoming
bluer. However, with the central 10h-1kpc the colors are remarkably
constant, the mean B-Rc color is 1.51 with a dispersion of only
0.06mag. The narrow photometric and color distributions of the BCGs,
the lack of "second-parameter" effects, as well as the unique rich
cluster environment of BCGs, argue that BCGs are the most homogeneous
distance indicators presently available for large-scale structure
research.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 119 The BCG sample
table3.dat 25 856 Brightest cluster galaxy aperture photometry
table4.dat 41 33 *Interrun photometry comparisons
table5.dat 31 21 External photometry comparisons
table6.dat 58 86 Galaxy redshift observations
table7.dat 62 29 Second-ranked galaxy observations
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Note on table4.dat: Comparisons are shown for the Rc-band Photometry at the
adopted metric aperture in the Local Group frame. Details of the runs are given
in Table 2. A portion of the comparisons Were based on the second-ranked
galaxies in some clusters.
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See also:
J/AJ/101/1561 : Isophotometry of ellipticals in Abell clusters (Porter+ 1991)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell galaxy number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
31- 35 I5 km/s czBCG Heliocentric BCG velocity
38- 42 I5 km/s czCl Heliocentric cluster velocity
45- 51 A7 --- Run Runs
53- 67 A15 --- Note Notes (1)
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Note (1): 1: The present BCG choice differs from the galaxy selected by
Hoessel et al., 1980ApJ...241..493H 1980ApJ...241..493H
2: A0419 appears to consist of two overlapping clusters at z=0.041 and
z=0.068. We have selected the lower redshift component.
3: The redshift for the BCG in A1139 (obtained from the CfA Redshift
Survey) had a relatively large measurement error of 170km/s
(see Table 6). However a remeasurement of its redshift by us
in 1992 gives a heliocentric velocity of 11495(±29)km/s,
within 35km/s of the less precise value.
4: A1631 appears to consist of two overlapping clusters at z=0.014 and
z=0.046. We have selected the higher redshift component.
5: This cluster was included to test for inhomogeneous velocity
bias at the sample edge (see Paper I,
Lauer et al., 1994ApJ...425..418L 1994ApJ...425..418L).
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Table 2: BCG imaging runs
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Run Date Telescope CCD Pixel Scale FOV
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1 1989 Oct CTIO 1.5m TI 800x800 (TI2) 0.273" 3.6'
2 1989 Nov KPNO 4m TI 800x800 (TI2) 0.299" 4.0'
3 1990 Nov CTIO 1.4m TI 800x800 (TI2) 0.273 3.6'
4 1991 Mar KPNO 2.1m Tek 1024x1024 (TE1K) 0.304" 5.2'
5 1991 Apr CTIO 1.5m Tek 1024x1024 (TEK1K-1) 0.434" 7.4'
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell cluster number
6- 11 F6.2 arcsec Rad Radius
13- 18 F6.3 mag Rc Rc magnitude
20- 24 F5.3 mag B-Rc ? B-Rc colour index
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell cluster number
5- 6 A2 --- m_Abell Designation in Abell cluster
8- 13 F6.3 mag Rc1 ? Run 1 Rc magnitude
15- 20 F6.3 mag Rc2 ? Run 2 Rc magnitude
22- 27 F6.3 mag Rc3 ? Run 3 Rc magnitude
29- 34 F6.3 mag Rc4 ? Run 4 Rc magnitude
36- 41 F6.3 mag Rc5 ? Run 5 Rc magnitude
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell number
6- 10 F5.2 arcsec Rad Radius
12- 17 F6.3 mag Rc Rc magnitude from Colless et al.
(1993MNRAS.262..475C 1993MNRAS.262..475C)
19- 24 F6.3 mag Rw Rc magnitude from this work
26- 31 F6.3 mag Rc-Rw Rc-Rw value (1)
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Note (1): Comparisons are shown for the Rc-band photoelectric photometry
of Colless et al. (1993MNRAS.262..475C 1993MNRAS.262..475C) (Rc) and the
present work (Rw), for the selected Colless et al. aperture
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell cluster number
5- 7 A3 --- m_Abell Designation in Abell cluster
9- 10 I2 h RAh Right ascension (J2000.0)
12- 13 I2 min RAm Right ascension (J2000.0)
15- 19 F5.2 s RAs Right ascension (J2000.0)
21 A1 --- DE- Declination sign
22- 23 I2 deg DEd Declination (J2000.0)
25- 26 I2 arcmin DEm Declination (J2000.0)
28- 31 F4.1 arcsec DEs Declination (J2000.0)
33- 37 I5 km/s cz Heliocentric velocity
39- 41 I3 km/s e_cz rms uncertainty on cz (1)
43 I1 --- Sources [1/3] Sources (2)
45- 64 A20 --- Note Notes (3)
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Note (1): For 1837-G1, the value printed, 3, was modified in 30.
Note (2): 1: MMT, J. Huchra & A. Zabludoff, private communication.
2: CTIO 1.5m, 1991 Spring
3: CTIO 1.5m, 1990 Fall.
Note (3): 1: This galaxy is a background object.
2: This galaxy is in a cluster beyond the 15000km/s heliocentric
velocity limit. The redshift measurement, however, was obtained
by us to better determine the membership of the z<0.05
cluster sample.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell cluster number
5- 6 A2 --- m_Abell Designation in Abell cluster
8- 9 I2 h RAh Right ascension (J2000.0)
11- 12 I2 min RAm Right ascension (J2000.0)
14- 18 F5.2 s RAs Right ascension (J2000.0)
20 A1 --- DE- Declination sign
21- 22 I2 deg DEd Declination (J2000.0)
24- 25 I2 arcmin DEm Declination (J2000.0)
27- 30 F4.1 arcsec DEs Declination (J2000.0)
32- 36 F5.3 mag M2-M1 Second ranked minus first ranked galaxies
absolute magnitudes
38- 42 F5.3 --- alpha α parameter (1)
44- 48 I5 km/s cz ? Heliocentric velocity
50- 52 I3 km/s e_cz ? rms uncertainty on cz
54- 73 A20 --- Note Notes
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Note (1): α is proportional to dlog(Lm/d)log(r|rmr)
where Lm is the total BCG luminosity within the circular aperture
of physical radius rm centered on the BCG nucleus.
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History: Prepared via OCR at CDS.
+ A227 from H. Andernach
(End) James Marcout, Patricia Bauer [CDS] 18-Sep-1997