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J/ApJ/442/523 Multiparam. Analysis, Einstein Sample. II. (Eskridge+ 1995)
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A Multiparametric Analysis of the Einstein Sample of Early-Type Galaxies. II.
Galaxy Formation History and Properties of the Interstellar Medium
Eskridge P.B., Fabbiano G., Kim D.-W.
<Astrophys. J. 442, 523 (1995)>
=1995ApJ...442..523E
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ADC_Keywords: Galaxies, optical; Interstellar medium
Keywords: galaxies: elliptical and lenticular, cD -- galaxies: ISM --
galaxies: structure -- X-rays: galaxies
Abstract:
We have conducted bivariate and multivariate statistical analysis of
data measuring the integrated luminosity, shape, and potential depth
of the Einstein sample of early-type galaxies (presented by Fabbiano
et al. =1992ApJS...80..531F). We find significant correlations between
the X-ray properties and the axial ratios (a/b) of our sample, such
that the roundest systems tend to have the highest L_X and L_X/L_B.
The most radio-loud objects are also the roundest. We confirm the
assertion of Bender et al. (1989A&A...217...35B) that galaxies with
high L_X are boxy (have negative a_4). Both a/b and a_4 are correlated
with L_B, but not with IRAS 12 um and 100 um luminosities. There are
strong correlations between L_X, Mg_2 and sigma_v in the sense that
those systems with the deepest potential wells have the highest L_X
and Mg_2. Thus the depth of the potential well appears to govern both
the ability to retain an ISM at the present epoch and to retain the
enriched ejecta of early star formation bursts. Both L_X/L_B and L_6
(the 6 cm radio luminosity) show threshold effects with sigma_v,
exhibiting sharp increases at log(sigma_v) ~ 2.2. Finally, there is
clearly an interrelationship between the various stellar and
structural parameters: The scatter in the bivariate relationships
between the shape parameters (a/b and a_4) and the depth parameter
(sigma_v) is a function of abundance in the sense that, for a given
a_4 or a/b, the systems with the highest sigma_v also have the highest
Mg_2. Furthermore, for a constant sigma_v, disky galaxies tend to have
higher Mg_2 than boxy ones. Alternatively, for a given abundance, boxy
ellipticals tend to be more massive than disky ellipticals. One
possibility is that early-type galaxies of a given mass, originating
from mergers (boxy ellipticals), have lower abundances than
"primordial" (disky) early-type galaxies. Another is that disky inner
isophotes are due not to primordial dissipational collapse, but to
either the self-gravitating inner disks of captured spirals or the
dissipational collapse of new disk structures from the premerger ISM.
The high measured nuclear Mg_2 values would thus be due to enrichment
from secondary bursts of star formation triggered by the merging
event.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1a.dat 63 113 Partial Spearman Rank Analysis: Trends with
Log(a/b), E+S0 Sample
tablea1b.dat 50 18 Partial Spearman Rank Analysis: Trends with
Log(a/b), Separate E and S0 Samples
tablea2.dat 63 143 Partial Spearman Rank Analysis: Trends with
Mg_2
tablea3.dat 63 155 Partial Spearman Rank Analysis: Trends with
sigma_v
tablea4.dat 63 233 Partial Spearman Rank Analysis: Trends with
a_4
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Comments for file: tablea1a.dat
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Table A1a shows the partial Spearman rank statistical analysis of
L_B--a/b, L_X--a/b, L_X/L_B--a/b, and L_6--a/b.
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Byte-by-byte Description of file: tablea1a.dat
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Bytes Format Units Label Explanations
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1-14 A14 --- Pair Test pair, if blank, record is a continuation
15-44 A30 --- Held Quantities to be held constant in the test
45-47 I3 --- Size Number of objects in the sample
48-55 F8.3 --- Spearman Partial Spearman rank statistic
57 A1 --- l_Prob Probability limiting character
58-63 F6.3 --- Prob Probability that the test pair shows a
correlation for this set of parameters
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Comments for file: tablea1b.dat
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Table A1b shows the partial Spearman rank statistical analysis of
separate E and S0 samples for L_B--a/b, L_X--a/b, and L_X/L_B--a/b
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Byte-by-byte Description of file: tablea1b.dat
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Bytes Format Units Label Explanations
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1-14 A14 --- Pair Test pair, if blank, record is a continuation
15-26 A12 --- Held Quantities to be held constant in the test
28-31 A4 --- Sample Sample designation, Es or S0s
32-34 I3 --- Size Number of objects in the sample
35-42 F8.3 --- Spearman Partial Spearman rank statistic
44 A1 --- l_Prob Probability limiting character
45-50 F6.3 --- Prob Probability that the test pair shows a
correlation for this set of parameters
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Comments for file: tablea2.dat
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Table A2 shows the partial Spearman rank statistical analysis of
L_B--Mg_2, L_X--Mg_2, L_X/L_B--Mg_2, a/b--Mg_2 and Mg_2--C_21.
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1-14 A14 --- Pair Test pair, if blank, record is a continuation
15-44 A30 --- Held Quantities to be held constant in the test
45-47 I3 --- Size Number of objects in the sample
48-55 F8.3 --- Spearman Partial Spearman rank statistic
57 A1 --- l_Prob Probability limiting character
58-63 F6.3 --- Prob Probability that the test pair shows a
correlation for this set of parameters
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Comments for file: tablea3.dat
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Table A3 shows the partial Spearman rank statistical analysis of
L_B--sigma_v, L_X--sigma_v, L_X/L_B--sigma_v, a/b--sigma_v, and
Mg_2--sigma_v.
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1-18 A18 --- Pair Test pair, if blank, record is a continuation
19-44 A26 --- Held Quantities to be held constant in the test
45-47 I3 --- Size Number of objects in the sample
48-55 F8.3 --- Spearman Partial Spearman rank statistic
57 A1 --- l_Prob Probability limiting character
58-63 F6.3 --- Prob Probability that the test pair shows a
correlation for this set of parameters
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Comments for file: tablea4.dat
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Table A4 shows the partial Spearman rank statistical analysis of
L_B--a_4, L_X--a_4, L_X/L_B--a_4, L_6--a_4, a/b--a_4, Mg_2--a_4,
and sigma_v--a_4
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1-14 A14 --- Pair Test pair, if blank, record is a continuation
15-44 A30 --- Held Quantities to be held constant in the test
45-47 I3 --- Size Number of objects in the sample
48-55 F8.3 --- Spearman Partial Spearman rank statistic
57 A1 --- l_Prob Probability limiting character
58-63 F6.3 --- Prob Probability that the test pair shows a
correlation for this set of parameters
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Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 06-May-1995
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(End) [CDS] 11-Jul-1995