J/AJ/106/530 Low surface brightness disk galaxies (Bothun+, 1993)
The small scale environment of low surface brightness disk galaxies
BOTHUN G.D., SCHOMBERT J.M., IMPEY C.D., SPRAYBERRY D., MCGAUGH S.S.
<Astron. J. 106, 530 (1993)>
=1993AJ....106..530B 1993AJ....106..530B (SIMBAD/NED Reference)
ADC_Keywords: Galaxies, optical; Redshifts
Abstract:
We use a sample of approximately 340 low surface brightness (LSB) disk
galaxies with measured redshifts in combination with the Center for
Astrophysics redshift survey to test the hypothesis that LSB galaxies
have a deficit of nearby companion galaxies compared to high
surface brightness (HSB) disk galaxies. We find a very strong
statistical deficit of galaxies located within a projected radius of
0.5 Mpc and within a velocity of 500 km/s around LSB disk galaxies
compared to HSB ones. Further, comparing LSB and HSB disk galaxies
which are located in the same portion of the sky indicates that the
average distance to the nearest neighbor is 1.7 times farther for LSB
disk galaxies. A Komologorov-Smirnoff test rules out, at greater than
the 99% confidence level, the hypothesis that the distribution of
nearest-neighbor distances is the same for HSB and LSB disk galaxies.
We speculate that LSB disk galaxies have relatively long formation time
scales and therefore must form in relative isolation. In addition, the
lack of tidal interactions over a Hubble time serves to suppress the
overall star-formation rate as no external trigger is available to help
clump the gas. The observed low surface densities of HI in combination
with the low probability of tidal interactions effectively prevents
these disk galaxies from evolving very rapidly.
File Summary:
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File Name Lrecl Records Explanations
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ReadMe 80 . This file
table1 43 86 Summary of Counts
table2 75 12 *Difference in mean counts
table3 50 15 Nearest-neighbor summary
table4 69 38 The most isolated LSB galaxies
table5 80 37 The most popular LSB galaxies
tables.tex 109 310 Tex version of the tables
format.tex 85 365 Format for tables.tex
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Note on table2: This table summarizes the differences between the means, in
units of sigma, in the comparison of various LSB and HSB samples. The POSS
and APM samples are compared at radii of 0.5, 1.0, 1.5, and 2.0 Mpc to the
total HSB sample as well as to the respective HSB sample that covers the
equivalent area of sky.
Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 8 A8 --- Sample Sample designation
11- 17 A7 km/s Vrange Velocity range
20- 22 F3.1 Mpc RadProj Projected radius out to which the counts
were made
25- 28 I4 --- Ngal Number of galaxies forming the sample mean
31- 32 I2 --- Nrej []? Number of rejected galaxies
35- 38 F4.2 --- Sample mean. In general, mean quantities are
calculated after one cycle of 2.5 sigma
projection.
40- 43 F4.2 --- e_ rms uncertainty in sample mean.
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 8 A8 --- Sample Sample designation
11- 17 A7 km/s Vrange Velocity range
20- 23 F4.1 --- POSS5 []? POSS comparison at 0.5 Mpc radius
25- 27 F3.1 --- POSS5B []? POSS at 0.5 Mpc obtained by considering
subset B in comparison to the POSS HSB sample
30- 32 F3.1 --- POSS10 []? POSS comparison at 1.0 Mpc radius
34- 36 F3.1 --- POSS10B []? POSS at 1.0 Mpc considering subset B
39- 41 F3.1 --- POSS15 []? POSS comparison at 1.5 Mpc radius
43- 45 F3.1 --- POSS15B []? POSS at 1.5 Mpc considering subset B
48- 50 F3.1 --- POSS20 []? POSS comparison at 2.0 Mpc radius
52- 54 F3.1 --- POSS20B []? POSS at 2.0 Mpc considering subset B
57- 60 F4.1 --- APM5 []? APM comparison at 0.5 Mpc radius
62- 65 F4.1 --- APM10 []? APM comparison at 1.0 Mpc radius
68- 70 F3.1 --- APM15 []? APM comparison at 1.5 Mpc radius
72- 75 F4.1 --- APM20 []? APM comparison at 2.0 Mpc radius
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Note:
Table2 summarizes the differences between the means, in units of sigma,
in the comparison of various LSB and HSB samples. The POSS and APM samples
are compared at radii of 0.5, 1.0, 1.5, and 2.0 Mpc to the total HSB sample
as well as to the respective HSB sample that covers the equivalent area of
sky.
Byte-by-byte Description of file: table3
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Bytes Format Units Label Explanations
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1- 8 A8 --- Sample Sample designation
11- 14 I4 --- Ngal Number of galaxies which have at least one
companion within a projected radius of 2.0 Mpc
17- 23 A7 km/s Vrange Velocity range
26- 29 F4.2 Mpc Dist Mean projected distance to the nearest
companion
31- 34 F4.2 Mpc e_Dist rms uncertainty on mean projected distance
37- 39 F3.2 --- DmaxPOSS []? KS statistic, Dmax, for the POSS sample
41- 42 I2 --- cl_DmaxPOSS []? Confidence level that Dmax exceeds
45- 47 F3.2 --- DamxAPN []? KS statistic, Dmax, for the APM sample
49- 50 I2 --- cl_DmaxAPM []? Confidence level that Dmax exceeds
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Byte-by-byte Description of file: table4
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name
10- 13 A4 --- Sample Sample designation (POSS or APM)
16- 17 I2 h RAh Right ascension 1950
19- 20 I2 min RAm Right ascension 1950
22- 25 F4.1 s RAs Right ascension 1950
27 A1 --- DE- Declination sign
28- 29 I2 deg DEd Declination 1950
31- 32 I2 arcmin DEm Declination 1950
34- 35 I2 arcsec DEs Declination 1950
38- 41 I4 km/s Vel Velocity
44- 69 A26 --- Com Comments
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Byte-by-byte Description of file: table5
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name
10- 13 A4 --- Sample Sample designation (POSS or APM)
16- 17 I2 h RAh Right ascension 1950
19- 20 I2 min RAm Right ascension 1950
22- 25 F4.1 s RAs Right ascension 1950
27 A1 --- DE- Declination sign
28- 29 I2 deg DEd Declination 1950
31- 32 I2 arcmin DEm Declination 1950
34- 35 I2 arcsec DEs Declination 1950
38- 41 I4 km/s Vel Velocity
44- 51 A8 --- BrightGal Name of the brightest galaxy within 2 Mpc or a
known structure near the galaxy
54- 80 A27 --- Com Comments
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Origin: AAS CD-ROM series, Volume 1, 1993
(End) Patricia Bauer [CDS] 25-Jul-1994