J/MNRAS/493/5089 HI asymmetries with LVHIS, VIVA, and HALOGAS (Reynolds+, 2020)
HI asymmetries in LVHIS, VIVA, and HALOGAS galaxies.
Reynolds T.N., Westmeier T., Staveley-Smith L., Chauhan G., Lagos C.D.P.
<Mon. Not. R. Astron. Soc., 493, 5089-5106 (2020)>
=2020MNRAS.493.5089R 2020MNRAS.493.5089R (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, group ; Galaxies ; Radio lines ;
H I data ; Spectroscopy
Keywords: galaxies: clusters: general - galaxies: groups: general -
radio lines: galaxies
Abstract:
We present an analysis of morphological, kinematic, and spectral
asymmetries in observations of atomic neutral hydrogen (HI) gas from
the Local Volume HI Survey (LVHIS), the VLA Imaging of Virgo in Atomic
Gas (VIVA) survey, and the Hydrogen Accretion in Local Galaxies
Survey. With the aim of investigating the impact of the local
environment density and stellar mass on the measured HI asymmetries in
future large HI surveys, we provide recommendations for the most
meaningful measures of asymmetry for use in future analysis. After
controlling for stellar mass, we find signs of statistically
significant trends of increasing asymmetries with local density. The
most significant trend we measure is for the normalized flipped
spectrum residual (Aspec), with mean LVHIS and VIVA values of
0.204±0.011 and 0.615±0.068 at average weighted 10th
nearest-neighbour galaxy number densities of log(ρ10/Mpc-3)
=-1.64 and 0.88, respectively. Looking ahead to the Widefield ASKAP
L-band Legacy All-sky Blind survey on the Australian Square Kilometre
Array Pathfinder, we estimate that the number of detections will be
sufficient to provide coverage over 5 orders of magnitude in both
local density and stellar mass increasing the dynamic range and
accuracy with which we can probe the effect of these properties on the
asymmetry in the distribution of atomic gas in galaxies.
Description:
We use the Local Volume HI Survey (LVHIS, Koribalski et al.
2018MNRAS.478.1611K 2018MNRAS.478.1611K, Cat. J/MNRAS/478/1611), the VLA Imaging of Virgo
in Atomic Gas survey (VIVA, Chung et al. 2009AJ....138.1741C 2009AJ....138.1741C), and the
Hydrogen Accretion in Local Galaxies survey (HALOGAS, Heald et al.
2011A&A...526A.118H 2011A&A...526A.118H) to investigate the influence of environment
density on measured morphological, kinematic, and spectral asymmetry
parameters.
The Local Volume HI Survey (LVHIS, Koribalski et al.
2018MNRAS.478.1611K 2018MNRAS.478.1611K, Cat. J/MNRAS/478/1611) was carried out on the
Australia Telescope Compact Array (ATCA), observing HI in 82 nearby
(<10Mpc) gas-rich spiral, dwarf, and irregular galaxies. The majority
of LVHIS galaxies are members of local groups or pairs and have at
least one close neighbour with an angular separation of <300arcsec
(projected separation <17kpc) and a systemic velocity <800km/s. We
exclude galaxies which are not covered by the 6dF Galaxy Survey due to
incompleteness. We use LVHIS stellar masses from Wang et al.
(2017MNRAS.472.3029W 2017MNRAS.472.3029W).
The VLA Imaging of Virgo in Atomic Gas survey (VIVA, Chung et al.
2009AJ....138.1741C 2009AJ....138.1741C) imaged 53 late-type galaxies in HI using the Karl
G. Jansky Very Large Array (VLA) at an angular resolution of
∼15arcsec. Here we use a subsample of 45 galaxies for which the
reduced HI spectral line cubes are available.
The Hydrogen Accretion in Local Galaxies survey (HALOGAS, Heald et al.
2011A&A...526A.118H 2011A&A...526A.118H) on the Westerbork Synthesis Radio Telescope
(WSRT) imaged 24 spiral galaxies in HI at an angular resolution of
∼40arcsec. The HALOGAS sample is composed of galaxies residing in
pairs and groups and includes both dominant and minor group members.
Here we use a subsample of 18 galaxies which lie within the SDSS
spectroscopic survey footprint (Strauss et al. 2002AJ....124.1810S 2002AJ....124.1810S).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 62 79 Asymmetry parameters for LVHIS galaxies
tablea2.dat 61 45 Asymmetry parameters for VIVA galaxies
tablea3.dat 61 18 Asymmetry parameters for HALOGAS galaxies
--------------------------------------------------------------------------------
See also:
J/MNRAS/478/1611 : Local Volume H I Survey (LVHIS) (Koribalski+, 2018)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Galaxy name (LVHISNNN)
10- 14 F5.2 [Mpc-3] logrho Logarithm of the environment density
computed using the 10 nearest neighbours
(Section 2.4)
16- 19 F4.1 [Msun] logMass ? Logarithm of the stellar mass
21- 22 I2 km/s DVsys Difference between the flux weighted mean
systemic velocity and the systemic velocity
defined as the mid-point of the spectrum at
50% of the spectrum's peak height
(Section 3.1.1)
24- 25 I2 km/s DVsysopt ? Difference between the flux weighted mean
systemic velocity from the HI spectrum and
the optical velocity (Section 3.1.1)
27- 31 F5.3 --- Aspec ? Spectrum residual (G1)
33- 36 F4.2 --- Aflux ? Ratio of the integrated flux in the left
and right halves of the spectrum divided at
the systemic velocity (Section 3.1.2)
38- 41 F4.2 --- Apeak ? Ratio between the left and right peaks of
the spectrum (Section 3.1.3)
43- 46 F4.2 --- Amap ? Bias corrected asymmetry parameter of
integrated intensity (moment 0) map
(Section 3.2.1)
48- 51 F4.2 --- ? Mean first harmonic coefficient from
Fourier analysis of moment 0 map over radii
smaller than the optical radius
(Section 3.2.2)
53- 56 F4.2 --- ? Mean first harmonic coefficient from
Fourier analysis of moment 0 map over radii
larger than the optical radius
(Section 3.2.2)
58- 62 F5.3 --- Avel ? Velocity asymmetry parameter (G2)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Name Galaxy name (NGCNNNN)
9- 13 F5.2 [Mpc-3] logrho Logarithm of the environment density
computed using the 10 nearest neighbours
(Section 2.4)
15- 18 F4.1 [Msun] logMass ? Logarithm of the stellar mass
20- 21 I2 km/s DVsys Difference between the flux weighted mean
systemic velocity and the systemic velocity
defined as the mid-point of the spectrum at
50% of the spectrum's peak height
(Section 3.1.1)
23- 24 I2 km/s DVsysopt ? Difference between the flux weighted mean
systemic velocity from the HI spectrum and
the optical velocity (Section 3.1.1)
26- 30 F5.3 --- Aspec Spectrum residual (G1)
32- 35 F4.2 --- Aflux Ratio of the integrated flux in the left
and right halves of the spectrum divided at
the systemic velocity (Section 3.1.2)
37- 40 F4.2 --- Apeak ? Ratio between the left and right peaks of
the spectrum (Section 3.1.3)
42- 45 F4.2 --- Amap Bias corrected asymmetry parameter of
integrated intensity (moment 0) map
(Section 3.2.1)
47- 50 F4.2 --- ? Mean first harmonic coefficient from
Fourier analysis of moment 0 map over radii
smaller than the optical radius
(Section 3.2.2)
52- 55 F4.2 --- ? Mean first harmonic coefficient from
Fourier analysis of moment 0 map over radii
larger than the optical radius
(Section 3.2.2)
57- 61 F5.3 --- Avel ? Velocity asymmetry parameter (G2)
--------------------------------------------------------------------------------
Global Notes:
Note (G1): Sum of the absolute differences between the flux in each channel of
the spectrum and the flux in the spectral channel of the spectrum
flipped about the systemic velocity normalized by the integrated
flux of the spectrum (Section 3.1.4).
Note (G2): Weighted median absolute deviation of the sum of the velocity field
and the velocity field rotated by 180deg about the galaxy centre
scaled by the 95th percentile of the difference map between the
original and rotated velocity fields (Section 3.2.3)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 11-May-2023