J/MNRAS/504/6198 GMC's properties cat. in Cen A mol. disc (Miura+, 2021)
A giant molecular cloud catalogue in the molecular disc of the elliptical
galaxy NGC 5128 (Centaurus A).
Miura R.E, Espada D, Hirota A, Henkel C, Verley S, Kobayashi M.I.N,
Matsushita S, Israel F.P, Vila-Vilaro B, Morokuma-Matsui K, Ott J,
Vlahakis C, Peck A.B, Aalto S, Hogerheijde M.R, Neumayer N, Iono D,
Kohno K, Takemura H, Komugi S
<Mon. Not. R. Astron. Soc. 504, 6198-6215 (2021)>
=2021MNRAS.504.6198M 2021MNRAS.504.6198M (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Galaxies, radio ; CO ; Radio lines ;
Millimetric/submm sources ; Photometry, millimetric/submm
Keywords: ISM: clouds - ISM: molecules -
galaxies: elliptical and lenticular, cD -
galaxies: individual (NGC 5128) - galaxies: ISM
Abstract:
We present the first census of giant molecular clouds (GMCs) complete
down to 106 M☉ and within the inner 4 kpc of the nearest giant
elliptical and powerful radio galaxy, Centaurus A. We identified 689
GMCs using CO(1-0) data with 1 arcsec spatial resolution (∼20 pc)
and 2 km/s velocity resolution obtained with the Atacama Large
Millimeter/submillimeter Array. The I(CO)-N(H2) conversion factor
based on the virial method is XCO = (2 ± 1) * 10^20 cm-2/(K.km/s)
for the entire molecular disc, consistent with that of the discs of
spiral galaxies including the Milky Way, and
XCO = (5 ± 2) * 1020cm-2/(K.km/s) for the circumnuclear disc
(CND; within a galactocentric radius of 200 pc). We obtained the GMC
mass spectrum distribution and find that the best truncated power-law
fit for the whole molecular disc, with index
γ ∝ -2.41 ± 0.02 and upper cut-off mass
∼ 1.3* 107 M☉, is also in agreement with that of nearby disc
galaxies. A trend is found in the mass spectrum index from steep to
shallow as we move to inner radii. Although the GMCs are in an
elliptical galaxy, the general GMC properties in the molecular disc
are as in spiral galaxies. However, in the CND, large offsets in the
line-width-size scaling relations (∼0.3 dex higher than those in the
GMCs in the molecular disc), a different XCO factor, and the
shallowest GMC mass distribution shape (γ = -1.1 ± 0.2) all
suggest that there the GMCs are most strongly affected by the presence
of the active galactic nucleus and/or shear motions.
Description:
The Atacama Large Millimeter/submillimeter Array (ALMA) is providing
an excellent view on what the molecular properties of truly elliptical
galaxies (e.g. Boizelle et al. 2017ApJ...845..170B 2017ApJ...845..170B ; Temi et al.
2018ApJ...858...17T 2018ApJ...858...17T ; Vila-Vilaro et al. 2019ApJ...870...39V 2019ApJ...870...39V). Here,
we present the GMC properties within the molecular disc of the closest
giant elliptical galaxy, NGC 5128, which is the host of the
radio-source Centaurus A. In this paper, we aim at providing a census
of the GMCs as traced by CO(1-0) down to GMC masses of 105 M_☉
and within the inner 4 kpc of an elliptical galaxy using high
resolution (∼20 pc), sensitivity (10 mJy/beam in 2 km/s
channels), and dynamic range observations obtained with ALMA. The
CO(1-0) line data were obtained with the 12 m, 7 m, and total
Power (TP) arrays and therefore the final combined maps have
information from small to large spatial scales.
Thanks to high angular resolution, we were able to resolve the
molecular component into tens of parsec scale clouds. Thus, we
identified GMCs with the cprops package (Rosolowsky & Leroy
2006PASP..118..590R 2006PASP..118..590R) and derived cloud properties. A total of 689 GMCs
were identified by the algorithm and their properties are listed in
table1.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 69 689 Properties of GMCs in the Molecular Disc
of Cen A
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See also:
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/ApJS/197/16 : CO observations of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)
J/ApJ/857/19 : ALMA view of GMCs in NGC 300 (Faesi+, 2018)
J/ApJ/803/16 : Giant molecular clouds in NGC4526 based on 12CO
(Utomo+, 2015)
J/ApJ/864/120 : ALMA obs. toward NGC 5253. I. Molecular clouds (Miura+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID GMC index number (ID) (1)
5- 10 F6.1 arcsec dRA Relative position in RA (deltaRA) (2)
12- 17 F6.1 arcsec dDE Relative position in Decl (deltaDE) (2)
19- 21 I3 km/s vLSR Local Standard of Rest velocity (vLSR)
23- 26 F4.1 km/s sigma Uncertainty in VLSR (sigmaV)
28- 30 F3.1 km/s e_sigma Velocity dispersion (e_sigmaV)
32- 33 I2 pc MajAxis Major axis size (sigmaMaj) (3)
35- 36 I2 pc MinAxis Minor axis size (sigmaMin) (3)
38- 40 I3 deg PA [] Position angle (PA) (4)
42- 43 I2 pc Rvir ? Virial radius (R) (5)
45- 46 I2 pc e_Rvir ? Mean error on Rvir (e_R)
48- 52 F5.1 Jy.km/s S Integrated CO(1-0) line flux density (S)
54- 56 F3.1 Jy.km/s e_S Mean error on S (e_S)
58- 61 I4 10+4Msun Mvir ? Virial mass (Mass) (5)
63- 66 I4 10+4Msun e_Mvir ? Mean error on Mvir (e_Mass)
68- 69 A2 --- Region Located region (Region) (6)
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Note (1): The GMC IDs are in order of increasing velocity (in the Local
Standard Rest frame).
Note (2): Intensity-weighted peak position relative to the AGN position at
(RA,DE) = (13:25:27.615,-43:01:08.805).
Note (3): Major and minor axes of the GMCs without beam deconvolution.
Note (4): Measured counterclockwise from north to east.
Note (5): Radius and virial masses are not presented for the GMCs whose minor
axis is too small to calculate a deconvolved minor axis.
Note (6): Identification code of the region where the GMC is located
as follows:
C = CND
S = Spiral arms
P = Parallelogram
O = Outer disk
C* = for the five excluded GMCs in the CND that fall within a
velocity range between 534 and 564 km/s
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 17-May-2024