2018ApJ...865...26D


Query : 2018ApJ...865...26D

2018ApJ...865...26D - Astrophys. J., 865, 26-26 (2018/September-3)

A high-resolution mosaic of the neutral hydrogen in the M81 Triplet.

DE BLOK W.J.G., WALTER F., FERGUSON A.M.N., BERNARD E.J., VAN DER HULST J.M., NEELEMAN M., LEROY A.K., OTT J., ZSCHAECHNER L.K., ZWAAN M.A., YUN M.S., LANGSTON G. and KEATING K.M.

Abstract (from CDS):

We present a 3° x 3°, 105-pointing, high-resolution neutral hydrogen (H I) mosaic of the M81 galaxy triplet, (including the main galaxies M81, M82, and NGC 3077, as well as dwarf galaxy NGC 2976) obtained with the Very Large Array C and D arrays. This H I synthesis mosaic uniformly covers the entire area and velocity range of the triplet. The observations have a resolution of ∼20'' or ∼420 pc. The data reveal many small-scale anomalous velocity features highlighting the complexity of the interacting M81 triplet. We compare our data with Green Bank Telescope observations of the same area. This comparison provides evidence for the presence of a substantial reservoir of low-column density gas in the northern part of the triplet, probably associated with M82. Such a reservoir is not found in the southern part. We report a number of newly discovered kpc-sized low-mass H I clouds with H I masses of a few times 106 M. A detailed analysis of their velocity widths show that their dynamical masses are much larger than their baryonic masses, which could indicate the presence of dark matter if the clouds are rotationally supported. However, due to their spatial and kinematical association with H I tidal features, it is more likely that the velocity widths indicate tidal effects or streaming motions. We do not find any clouds that are not associated with tidal features down to an H I mass limit of a few times 104 M. We compare the H I column densities with resolved stellar density maps and find a star formation threshold around 3-6 x 1020 cm–2. We investigate the widths of the H I velocity profiles in the triplet and find that extreme velocity dispersions can be explained by a superposition of multiple components along the line of sight near M81 as well as winds or outflows around M82. The velocity dispersions found are high enough that these processes could explain the linewidths of damped-Lyα absorbers observed at high redshift.

Abstract Copyright: © 2018. The American Astronomical Society. All rights reserved.

Journal keyword(s): galaxies: fundamental parameters - galaxies: individual: (M81, M82, NGC 3077) - galaxies: ISM - galaxies: kinematics and dynamics - radio lines: galaxies

CDS comments: Figure 11: Complex A and Cloud B are not in SIMBAD.

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1333 1
2 NAME NGC 2403 Group GrG 07 36.9 +65 36           ~ 21 0
3 NAME Leo T G 09 34 53.4 +17 03 05     15.1     ~ 330 0
4 NGC 2976 GiP 09 47 15.458 +67 54 58.97 11.77 11.03 10.16 9.51   ~ 604 1
5 4C 66.09 AGN 09 49 12.16518 +66 14 59.5874   21.6 21.6     ~ 50 1
6 [CLY2008] 1 HI 09 50 07.2 +69 55 56           ~ 5 1
7 NAME M 81-82 Group GrG 09 55 +69.1           ~ 654 0
8 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 4078 5
9 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5478 6
10 NAME M 81 Triplet GrG 09 56.0 +69 00           ~ 19 1
11 UGC 5336 G 09 57 32.1 +69 02 46 15.19 15.15 14.10 14.12   ~ 297 4
12 NGC 3077 GiP 10 03 19.0965510921 +68 44 01.556166166 11.23 10.85 10.14 9.74   ~ 707 0
13 NAME Garland G 10 03 43.1 +68 41 32           ~ 55 2
14 NAME M81 dwB G 10 05 30.44 +70 21 53.9 15.95 15.56 15.09 14.87   ~ 182 1
15 NAME Leo P BiC 10 21 45.123 +18 05 16.89           ~ 168 0

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2021.09.19-19:50:09

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