J/MNRAS/516/2337 HI obs. with FAST for 113 red spirals galaxies (Wang+, 2022)
H I content of massive red spiral galaxies observed by FAST.
Wang L., Zheng Z., Hao C.-N., Guo R., Li R., Qian L., Xie L., Shi Y.,
Zou H., Cao Y., Chen Y., Xia X.
<Mon. Not. R. Astron. Soc. 516, 2337-2347 (2022)>
=2022MNRAS.516.2337W 2022MNRAS.516.2337W (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Spectroscopy ; Redshifts ; Optical ; Radio sources ;
Radio lines ; Positional data ; Equivalent widths ;
Photometry, hydrogen-line
Keywords: galaxies: disc - galaxies: evolution - galaxies: formation
Abstract:
A sample of 279 massive red spirals was selected optically by Guo et
al. 2020ApJ...897..162G 2020ApJ...897..162G , among which 166 galaxies have been observed
by the ALFALFA survey. In this work, we observe H I content of the
rest 113 massive red spiral galaxies using the Five- hundred-meter
Aperture Spherical radio Telescope (FAST). 75 of the 113 galaxies have
H I detection with a signal-to-noise ratio (S/N) greater than 4.7.
Compared with the red spirals in the same sample that have been
observed by the ALFALFA survey, galaxies observed by FAST have on
average a higher S/N, and reach to a lower H I mass. To investigate
why many red spirals contain a significant amount of H I mass, we
check colour profiles of the massive red spirals using images observed
by the DESI Legacy Imaging Surveys. We find that galaxies with H I
detection have bluer outer discs than the galaxies without H I
detection, for both ALFALFA and FAST samples. For galaxies with H I
detection, there exists a clear correlation between galaxy H I mass
and g-r colour at outer radius: galaxies with higher H I masses have
bluer outer discs. The results indicate that optically selected
massive red spirals are not fully quenched, and the H I gas observed
in many of the galaxies may exist in their outer blue discs.
Description:
In this work, we obtain a complete census of the H I content of
previous 279 massive red spiral galaxy sample by observing remaining
113 red spirals that are not covered by ALFALFA using
Five-hundred-meter Aperture Spherical radio Telescope (FAST). This
almost doubles the sample size of massive red spirals with H I
observations and hence will enable us to have a better statistics of
the H I content of such systems. Then, H I observations obtained
by FAST and ALFALFA are compared in their capabilities in detecting
atomic gas of galaxies.
Firstly, we consider 279 massive red spiral galaxies selected with an
SDSS-DR7 catalogue of galaxies. We isolate 113 galaxies that are not
in the ALFALFA region as exposed in figure 1 of the section 2.
Secondly as presented in section 2.2, we proceed to FAST observations
having strong power in detecting H I 21cm spectra and coverring a
frequency range of 1.05-1.45 GHz. Data reduction and their analysis
are fully explained in this section which gives rise to
spectrophometric results as fluxes, redshifts, EWs, S/N and mass of H I
for the selected galaxies (i.e see figure 2 for an observed and
analysed spectrum example). Finally, helping for FIRST and ALFALFA
comparisons, its results are provided in table1.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 113 Results of the massive red spirals observed
by FAST
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See also:
J/ApJS/210/3 : SDSS bulge, disk and total stellar mass estimates
(Mendel+, 2014)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/ApJ/733/74 : GALEX - SDSS properties of local galaxies (Lemonias+, 2011)
II/294 : The SDSS Photometric Catalog, Release 7
(Adelman-McCarthy+, 2009)
J/MNRAS/474/1909 : Passive spiral galaxies quench (Fraser-McKelvie+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 I18 --- objID SDSS-DR7 object identifier of galaxies
from Mendel et al. 2014ApJS..210....3M 2014ApJS..210....3M,
Cat. J/ApJS/210/3 (objID)
20- 26 F7.3 deg RAdeg Right ascension (J2000) (ra)
28- 35 F8.4 deg DEdeg Declination (J2000) (dec)
37- 42 F6.4 --- z Optical spectroscopic redshift of the
galaxy (z)
44- 46 I3 km/s W50 ? Rest-frame velocity width of the HI
profile at 50 per cent level of the profile
peaks (W50) (1)
48- 51 F4.2 mJy sigma The RMS flux noise of the spectrum
(σrms) (2)
53- 56 F4.2 Jy.km/s S21 ? Rest-frame velocity-integrated 21 cm
H I line flux (S21) (3)
58- 62 F5.2 [Msun] log(MHI) ? Logarithm of H I mass of the galaxy
(logMHI/M☉) (4)
64- 68 F5.2 [Msun] e_log(MHI) ? Uncertainty of log (MHI) (σlogMHI)
(5)
70- 74 F5.1 --- S/N ? Signal to noise ratio (S/N) (6)
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Note (1): As shown in section 2.2, the analysis point v., W50 is defined as
the difference between the two velocities that correspond to the two
frequencies. As for ALFALFA, the maximum flux density value is
calculated as the observed peak flux density minus the rms, to
correct for the contribution of noise. Following equation (20) of
Meyer et al. 2017PASA...34...52M 2017PASA...34...52M, we calculate W50 with equation 1
of section 2.2.
Note (2): As shown in section 2.2, the analysis point iv., the rms noise of the
spectrum σrms is calculated on the two continuum regions at
the two sides of the H I signal, after continuum subtraction.
Note (3): As shown in section 2.2, the analysis point vi., we determine the
central frequency of the HI line by the optical spectroscopic redshift
of the galaxy and the frequency range of the H I line is selected by
hand. Then the total S21 flux is then obtained by integrating the
continuum-subtracted H I flux density over this frequency range.
Note (4): As shown in section 2.2, the analysis point viii., MHI is derived from
the integrated H I flux S21 and distance following the equation
provided by Meyer et al. 2017PASA...34...52M 2017PASA...34...52M, under the assumption
that the H I content is optically thin as equation 3 of section 2.2.
Note (5): As shown in section 2.2, the error of the H I mass is calculated
similar as adopted by ALFALFA (Haynes et al. 2018ApJ...861...49H 2018ApJ...861...49H,
Cat. J/ApJ/861/49), to include systematic uncertainty in the flux
calibration, where the uncertainty of distance has been ignored.
Thus, we expressed σlogMHI with S21 and σS21 as the
equation 4 of section 2.2.
Note (6): As shown in section 2.2, the analysis point vii., to be compared to
ALFALFA catalogue, similarly we follow the S/N estimate as the
equation 2 of section 2.2.
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 22-Jul-2025