J/MNRAS/446/2823 CO and CaT derived sigma in spiral galaxies (Riffel+, 2015)
Differences between CO- and calcium triplet-derived velocity dispersions in
spiral galaxies: evidence for central star formation?
Riffel R.A., Ho L.C., Mason R., Rodriguez-Ardila A., Martins L., Riffel R.,
Diaz R., Colina L., Alonso-herrero A., Flohic H., Gonzalez Martin O.,
Lira P., McDermid R., Ramos Almeida C., Schiavon R., Thanjavur K.,
Ruschel-Dutra D., Winge C., Perlman E.
<Mon. Not. R. Astron. Soc., 446, 2823-2836 (2015)>
=2015MNRAS.446.2823R 2015MNRAS.446.2823R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Velocity dispersion ; Spectroscopy
Keywords: galaxies: active - galaxies: kinematics and dynamics -
galaxies: star formation - infrared: galaxies
Abstract:
We examine the stellar velocity dispersions (σ) of a sample of
48 galaxies, 35 of which are spirals, from the Palomar nearby galaxy
survey. It is known that for ultra-luminous infrared galaxies (ULIRGs)
and merger remnants, the σ derived from the near-infrared CO
band heads is smaller than that measured from optical lines, while no
discrepancy between these measurements is found for early-type
galaxies. No such studies are available for spiral galaxies - the
subject of this paper. We used cross-dispersed spectroscopic data
obtained with the Gemini Near-Infrared Spectrograph, with spectral
coverage from 0.85 to 2.5µm, to obtain σ measurements from
the 2.29µm CO band heads (σCO) and the 0.85µm calcium
triplet (σCaT). For the spiral galaxies in the sample, we
found that σCO is smaller than σCaT, with a mean
fractional difference of 14.3 per cent. The best fit to the data is
given by σopt=(46.0±18.1)+(0.85±0.12)σCO. This
'σ-discrepancy' may be related to the presence of warm dust, as
suggested by a slight correlation between the discrepancy and the
infrared luminosity. This is consistent with studies that have found
no σ-discrepancy in dust-poor early-type galaxies, and a much
larger discrepancy in dusty merger remnants and ULIRGs. That
σCO is lower than σopt may also indicate the presence of
a dynamically cold stellar population component. This would agree with
the spatial correspondence between low-σCO and
young/intermediate-age stellar populations that has been observed in
spatially resolved spectroscopy of a handful of galaxies.
Description:
The sample of galaxies used in this work comprises 48 objects selected
from the Palomar spectroscopic survey of nearby galaxies (Ho,
Filippenko & Sargent 1995, Cat. J/ApJS/98/477, 1997, Cat.
J/ApJS/112/315), covering a wide range of luminosity and nuclear
activity type. Some properties of the sample are shown in Table 1,
while full details of the overall programme, sample, observations, and
data reduction are given in Mason et al. (submitted).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 107 47 Properties of the galaxies from our sample
tableb1.dat 58 323 Stellar templates used for each galaxy to
derive the stellar kinematics
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See also:
J/ApJS/98/477 : Optical spectral atlas of Seyfert nuclei (Ho+ 1995)
J/ApJS/112/315 : Spectroscopic parameters of Seyfert nuclei (Ho+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Gal Galaxy name
9 A1 --- n_Gal [b] Note on Gal (1)
12- 26 A15 --- HType Hubble type from Ho et al.
(1997, Cat. J/ApJS/112/315)
28- 36 A9 --- NAct Nuclear Activity from Ho et al.
(1997, Cat. J/ApJS/112/315) (2)
38- 42 F5.1 km/s sigmaCO CO derived velocity dispersion
44- 47 F4.1 km/s e_sigmaCO rms uncertainty on sigmaCO
48 A1 --- n_sigmaCO [a] Note on sigmaCO (1)
51- 55 F5.1 km/s sigmaCaT ?=- CaT derived velocity dispersion (3)
57- 60 F4.1 km/s e_sigmaCaT ? rms uncertainty on sigmaCaT
61 A1 --- n_sigmaCaT [a] Note on sigmaCaT (1)
63- 67 F5.2 --- h3CO Stellar kinematic parameter h3 derived from CO
69- 72 F4.2 --- e_h3CO rms uncertainty on h3CO (4)
74- 78 F5.2 --- h3CaT ?=- Stellar kinematic parameter h3 derived
from CaT (3)
80- 83 F4.2 --- e_h3CaT ? rms uncertainty on h3CaT (4)
85- 89 F5.2 --- h4CO Stellar kinematic parameter h4 derived from CO
91- 94 F4.2 --- e_h4CO rms uncertainty on h4CO (4)
96-100 F5.2 --- h4CaT ?=- Stellar kinematic parameter h4 derived
from CaT (3)
102-105 F4.2 --- e_h4CaT ? rms uncertainty on h4CaT (4)
107 A1 --- Conf [ab] Instrumental configuration used for
the observations (5)
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Note (1): Notes as follows:
a = The measured sigma is smaller than the instrumental sigma.
b = The second CO band was excluded from the fitting due to contamination
by the [CaVIII] 2.322um emission.
Note (2): Nuclear Activity code as follows:
S = Seyfert nucleus
L = LINER
T = transition object
H = HII nucleus
':' means that the classification is uncertain
Note (5): Configuration code as follows:
a = observations done before 2012 November and has an instrumental sigma
of 65km/s for both spectral regions
b = observations done after 2012 November and has an instrumental sigma
of 100 and 110km/s for the CO and CaT regions
Note (3): The dashes in the table are due to the fact that for a few objects,
we were not able to get a good fit of the spectrum in one of the spectral
regions due to a low S/N ratio or non-detection of the absorption lines.
Note (4): The uncertainties included for the kinematic parameters are those
that PPXF outputs.
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Gal Galaxy name
10- 16 A7 --- SpType1 CaT region spectral type
18- 30 A13 --- Star1 CaT region star name (1)
34- 35 I2 % W1 ? CaT region weight (1)
37- 44 A8 --- SpType2 CO region spectral type
46- 55 A10 --- Star2 CO region star name (2)
57- 58 I2 % W2 ? CO region weight (2)
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Note (1): Name and percentual contribution of the star to the fit of the galaxy
spectrum for the Ca triplet region. Templates are from Cenarro et. al.
(2001MNRAS.326..959C 2001MNRAS.326..959C, Cat. J/MNRAS/326/959) and for some cluster stars, the
authors list the positions of the stars in the HR diagram
(SGB: subgiant branch; GB: giant branch; HB: horizontal branch).
Note (2): Name and percentual contribution of the star to the fit of the galaxy
spectrum for the CO spectral region. Templates are from Winge, Riffel &
Storchi-Bergmann (2009ApJS..185..186W 2009ApJS..185..186W).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Jun-2015