J/ApJS/95/401 Clusters of galaxies position angles (Plionis 1994)
Position angles and alignments of clusters of galaxies
Plionis M.
<Astrophys. J. Suppl. Ser. 95, 401 (1994)>
=1994ApJS...95..401P 1994ApJS...95..401P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy
Keywords: galaxies: clustering - galaxies: fundamental parameters
Abstract:
The position angles of a large number of Abell and Shectman clusters,
identified in the Lick map as surface galaxy-density enhancements, are
estimated. I determine the major axis orientation of a total of 637
clusters, of which 448 are Shectman clusters (202 of which are also
Abell clusters) and 189 are Abell clusters not originally detected by
Shectman due to his adopted density threshold. Using published
redshifts for 277 of these clusters I have detected strong nearest
neighbor alignments over scales up to ∼15h-1Mpc at a≳2.5-3σ
significance level, while quite weak alignments are detected even up
to ∼60h-1Mpc. A more significant alignment signal (∼4σ) is
detected among all neighbors residing in superclusters and having
separations ≲ 10h-1Mpc. Again, weaker but significant alignments
are found when larger separations are considered. Since my cluster
sample is neither volume limited nor redshift complete (which would
have tended to wash out any real alignment signal), the alignments
detected should reflect a real and possibly a stronger underline
effect.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1a.dat 35 448 Mean position angles of Abell and Shectman clusters
identified at the 3.6 level
table1b.dat 15 32 Position angles of Abell clusters, identified at
the 3.6 level but estimated at the 2.5 level
table1c.dat 15 41 Position angles of Abell clusters, identified at
the 3.6 level but estimated at the 1.8 level
table1d.dat 15 123 *Position angles of Abell clusters, identified at
the 2.5 level but estimated at the 1.8 level
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Note on table1d.dat: Note that there are 12 clusters in common with
table1b, which for comparison reasons we have not averaged their
estimated position angles.
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Byte-by-byte Description of file: table1a.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Shect ? Cluster Shectman number (1985ApJS...57...77S 1985ApJS...57...77S)
5- 8 I4 --- Abell ? Cluster Abell number (Cat. VII/4)
10- 11 I2 --- Level Number of levels (1)
13- 14 I2 --- Ncells Number of cells, minimum if n_Ncells='-' (2)
15 A1 --- --- [-] - for interval
16- 17 I2 --- Ncells2 ? Maximun number of cells
19- 23 F5.1 deg PA Position angle
25- 28 F4.1 deg e_PA ? rms uncertainty on PA (3)
30- 34 F5.1 deg PAMed ? Median position angle (3)
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Note (1): Number of overdensity levels used to estimate the position angle
Note (2): Minimum and maximum number of 10'x10' cells, Ncells, defining the
cluster sampling area (at the different overdensity levels).
Note (3): For the cases were the position angle was determined in three or more
overdensity levels, the error and the median value are also listed.
In those cases where four levels were used, we average the two
central PA values
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Byte-by-byte Description of file: table1b.dat table1c.dat table1d.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Abell Abell number
6- 8 I3 --- Ncells Number of cells
10- 14 F5.1 deg PA Position angle
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History: Prepared via OCR at CDS.
* 20-Jul-1998: several OCR errors corrected thanks to the catalog
A222 supplied by A. Andernach originated from Manolis Plionis
(End) Patricia Bauer [CDS] 30-May-1997