J/A+A/366/68 Spectrophotometric indices from galaxy bulges (Prugniel+, 2001)
The formation of galaxy bulges: Spectrophotometric constraints
Prugniel P., Maubon G., Simien F.
<Astron. Astrophys. 366, 68 (2001)>
=2001A&A...366...68P 2001A&A...366...68P
ADC_Keywords: Galaxies, spectra ; Spectrophotometry
Keywords: galaxies: spiral - galaxies: fundamental parameters -
galaxies: stellar content - galaxies: evolution
Description:
We have measured Mg2, Fe5270 and Fe5335 spectrophotometric indices
(LICK system) in the bulge of 89 galaxies, mostly spirals from the
Heraudeau sample. The indices are reduced to a null velocity
dispersion and normalized to an aperture of 0.2h-1kpc. The mean
errors are 0.009 mag on Mg2, and 0.3Å on the iron indices. These
measurements almost double the amount of similar data already
available on spiral galaxies.
Our data confirm the existence of the relation between Mg2 and
sigma0, the central stellar velocity dispersion; and we find an even
tighter relation between Mg2 and Vmaxrot, the maximum rotational
velocity of the galaxy, deduced from HI observations. For the most
massive bulges these correlations may be interpreted as a
mass-metallicity relation. However, the presence of young stellar
populations, traced by the detection of [OIII]λ500.7nm
emission, provides a clear evidence that age effects play a role.
Since the contribution of the young population is anti-correlated with
the mass of the galaxy, it continues the Mg2 vs. sigma0 relation
toward the low sigma0 and globally increases its slope. We present
also evidence for a new positive correlation between Fe indices and
sigma0 and for a significant correlation between the line strength
indices and the total or disk luminosity.
We propose to model the whole sequence of bulges within the following
framework:
Bulges are composed of a primary population formed prior to the disk
during the initial collapse and a secondary population formed along
the evolution. The whole family of bulges can be classified in three
classes: (A) The bulges dominated by a young population are generally
small, have ionized gas, low velocity dispersion and low line
strengths. (B) The bulges dominated by the primary population lie
along the mass metallicity sequence defined for elliptical galaxies.
(C) The bulges where the secondary population is significant are less
Mg-overabundant than B-type bulges and deviate from the Mg2 vs.
sigma0 relation of elliptical galaxies.
The original data are available in Hypercat:
http://www-obs.univ-lyon1.fr/hypercat
The tables of measurements and the extracted 1D spectra are also
available in the present archive set.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 130 93 Catalog elements and final measurements
table3.dat 111 155 Individual measurements
fits/* . 155 Fully reduced and extracted spectra
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See also:
http://www-obs.univ-lyon1.fr/hypercat/ : the HYPERCAT database
J/A+AS/132/255 : A catalogue of Mg2 indices (Golev+ 1998)
J/A+AS/136/519 : Central Mg2 indices for early-type galaxies (Golev+ 1999)
J/A+AS/133/317 : Stellar kinematics in spiral galaxies. I. (Heraudeau+ 1998)
J/A+AS/136/509 : Stellar kinematics in spiral galaxies. II. (Heraudeau+ 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name *Normalized galaxy identifier
11- 12 I2 h RAh *? Right Ascension 1950 (hours)
13- 14 I2 min RAm ? Right Ascension 1950 (minutes)
15- 18 F4.1 s RAs ? Right Ascension 1950 (seconds)
19 A1 --- DE- *? Declination 1950 (sign)
20- 21 I2 deg DEd ? Declination 1950 (degrees)
22- 23 I2 arcmin DEm ? Declination 1950 (minutes)
24- 25 I2 arcsec DEs ? Declination 1950 (seconds)
29- 32 A4 --- MType Morphological type (from PGC96)
34- 39 F6.0 km/s Vdist *Distance velocity (from Hypercat)
43- 45 I3 km/s Vmrot Maximum velocity of rotation (from PGC96)
47- 49 I3 km/s Sig0 Central velocity dispersion (from Hypercat)
52- 58 F7.3 kpc R6 *R6 radius projected on minor axis
60- 60 I1 --- Nobs Number of individual observations
62- 67 F6.4 mag Mg2 Fully corrected Mg2 index
69- 74 F6.4 mag e_Mg2 Error on Mg2
76- 81 F6.2 0.1nm OIII OIII (5007) equivalent width
83- 88 F6.2 0.1nm e_OIII ?=-99.99 Formal fit error on OIII
90- 95 F6.3 0.1nm Fe5270 ?=-9.999 Iron 5270 index
97-102 F6.3 0.1nm e_Fe5270 ?=-9.999 error on Fe5270
104-109 F6.3 0.1nm Fe5335 ?=-9.999 Iron 5335 index
111-116 F6.3 0.1nm e_Fe5335 ?=-9.999 error on Fe5335
118-123 F6.3 0.1nm Fe ?=-9.999 Combined Iron index
126-130 F5.3 0.1nm e_Fe ?=-9.999 error on Fe
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Note on Name:
The Name has been adopted by descending the hierarchy:
1) NGC (Cat. VII/118)
2) IC (Cat. VII/118)
3) UGC (Cat. VII/26)
The galaxy identifiers follow the rule already used in
Prugniel & Simien, 1996, Cat. J/A+A/309/749 and in
Prugniel et al. 1998, Cat. J/A+AS/127/117.
Note on RAh, DE-:
No coordinates for Galactic Bulge
Note on Vdist:
The distance in h-1Mpc is deduced from the distance velocity as
distance = Vdist/100.
The flow-smoothed velocity used for aperture correction (defined
as the velocity of the cosmologic flow associated with the galaxy)
is determined iteratively by averaging the velocity of galaxies
found in the neighbourhood of a given galaxy. It is corrected for the
deviations from the linear flow assuming a Great Attractor, Virgocentric
infall and Local Group Anomaly. See Golev et al., 1999A&AS..136..519G 1999A&AS..136..519G
Note on R6:
This radius is calculated on the galaxy equivalent axis according to
Jablonka (1996AJ....112.1415J 1996AJ....112.1415J) and decomposition of Heraudeau (1996,
Thesis, Observatoire de Lyon).
There are 6 galaxies decomposed by Heraudeau but with undefined R6:
NGC 0918, NGC 2146, NGC 2715, NGC 2726, NGC 2742, NGC 7177
as defined in the paper.
In this table they have the classical undefined value "-99.999"
Note for local group galaxies, Milky Way bulge and NGC4594:
The line strength indices for the local galaxies and NGC4594 are taken
from Hypercat. The maximum velocity of rotation of the Milky Way comes
from Fish & Tremaine (1991ARA&A..29..409F 1991ARA&A..29..409F)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Faid *Identification of observation
17- 36 A20 --- FileName Spectra file name in "fits" subdirectory
38- 46 A9 --- Name Normalized galaxy identifier
49- 55 F7.0 km/s Vhel Heliocentric cz from Hypercat
57- 62 F6.4 mag Mg2 *Measured Mg2 index
64- 69 F6.4 mag e_Mg2 *Uncertainty of Mg2 index
71- 76 F6.2 0.1nm OIII *OIII 5007 A Equivalent width
78- 83 F6.2 0.1nm e_OIII ?=-99.99 Uncertainty on OIII
85- 90 F6.3 0.1nm Fe5270 Uncorrected measured Fe5270 index
92- 97 F6.3 0.1nm e_Fe5270 Error on Fe5270
99-104 F6.3 0.1nm Fe5335 Uncorrected measured Fe5335 index
106-111 F6.3 0.1nm e_Fe5335 Error on Fe5335
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Note on Faid:
Identification of the actual observation in the Hypercat FITS archive.
It may be used to access to the image. For example, to access to
L94121HP1/00062, use URL:
http://www-obs.univ-lyon1.fr/hypercat/fG.cgi?n=11&c=i&o=fa:L94121HP1/00062
From the resulting page (or similar page for the other observations)
it is possible to customize a specific extraction using the html
pipeline-editor.
The observations measured in the present paper are from the
following Hypercat datasets:
L93011HP1
L93021HP1
L93121HP1
L94021HP1
L94121HP1
L95012HP1
An Hypertext listing of all the observations (including template stars)
may be obtained at:
http://www-obs.univ-lyon1.fr/hypercat/fG.cgi?n=11&b=L93011HP1;L93021HP1;L93121HP1;L94021HP1;L94121HP1;L95012HP1
For each observation, a link to the pipeline-editor is available from
this page.
Note on Mg2:
The Mg2-index in magnitudes, uncorrected
Note on e_Mg2:
Raw error on uncorrected Mg2 (See Cardiel, 1998A&AS..127..597C 1998A&AS..127..597C)
Note on OIII:
Equivalent width of OIII in 0.1nm determined by a gaussian fit with a
constant baseline. The associated error is the formal fitting error.
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Description of files: L*.fits
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The FITS files presented in this paper contain the fully reduced and
extracted spectra corresponding to the 157 individual observations.
The original observations are described in:
J/A+AS/133/317 : Stellar kinematics in spiral galaxies (Heraudeau+ 1998)
J/A+AS/136/509 : Stellar kinematics in spiral galaxies. II. (Heraudeau+ 1999)
They were generated by the following Hypercat pipeline:
z=ffc|spk[2.2,3,2]|wrs|sks|xto[n,2.4]|prj[a,1]|fca|msk[w5575,n1,w5582,n1]
The extraction can be re-done customizing some parameters by using a
mirror of Hypercat: for example the extraction of L93021HP1_00164.fits
may be obtained by downloading the URL:
http://www-obs.univ-lyon1.fr/hypercat/fG.cgi?n=11&c=i&o=L93021HP1/00164&z=ffc|spk[2.2,3,2]|wrs|sks|xto[n,2.4]|prj[a,1]|fca|msk[w5575,n1,w5582,n1]&a=mime:application/x-fits
To define a customized extraction for the same observation, connect to
the address:
http://www-obs.univ-lyon1.fr/hypercat/fG.cgi?n=11&c=i&o=fa:L93021HP1/00164
and use the pipeline-editor.
The detailed syntax of the pipeline command and of Hypercat requests
may evolve in future versions and it is advised to consult the
documentation on a web mirror of Hypercat.
The detailed description of the pipeline procedures may be found in
the documentation of Hypercat. We describe hereafter the actual (Jan
2001) parameterization of the extraction:
1- flat-field correction: ffc
We subtracted a constant bias and divided by a normalized flat-field.
The flat-field was computed by averaging internal flat-fields taken
with a Tungsten lamp. The result was normalized to unity by dividing
by a smoothed continuum (to remove the effect of the "temperature" of
the lamp. Because the procedure do not give the proper response of the
system along the spatial direction, we used sky flat-fields to correct
the spatial response of normalized flat-field.
2- Spikes removal: spk
Spikes ("cosmic rays") are deleted if their FWHM is smaller than 2.2
pixel. This is larger than the spectral resolution, but we used this
parameter in order to have a "more efficient" clipping. We checked
on a few images that this parameter did not result in spurious
detections. The spike removal is iterated twice in order to clip the
wings of extended events. Note that it is preferable to include this
step before the wavelength resampling which slightly smooth the
signal.
3- Wavelength resampling: wrs
It is done automatically using the calibration relation pointed to
by the keyword H_WCALIB in the header. We used a cubic spline
interpolator.
4- Extraction of the subimage: xto
We extracted a region of 5 pixels wide around the light-peak of the
object
5- Projection to the wavelength axis: prj
We took the average, at each wavelength point, of the extracted
region
6- Flux calibration: fca
The spectrum is divided by the flux calibration relation pointed to by
the keyword H_FCALIB.
The flux calibration used for the whole dataset is in:
fa:LCARELEC_/99001
It was computed by comparing the single observation of SAO55164
fa:L93011HP1/00013 versus the Jacoby's spectrum: fa:L1984JACO/00097
7- Masking: msk
We masked the wavelength region under the OI [5577Å] telluric
emission because the signal to noise is much decreased at this
location. We did not mask the other bright night-sky emission line
due to the urban light (Hg at 546.074 nm), though in some case the
residuals from the sky subtraction are not negligible.
After the pipeline extraction the files were visually inspected for
validating the process. We found that the following files presented
defects:
L93021HP1/00066 Something at 5509Å
L93021HP1/00242 spk @5318
L93021HP1/00279 spk @5321
L93121HP1/00044 spk @5536
L93121HP1/00083 spk @5339
L94021HP1/00016 spk @5604
L94021HP1/00020 very badly subtracted sky line due to
LIDAR laser beam @5456
L94021HP1/00086 spk @5637
L94021HP1/00099 spk @5396
L94021HP1/00133 spk @5120 @5458
L94021HP1/00152 spk @5650
L95012HP1/00007 spk @5183
We did not edit all these files to mask the defects. Only the
following was post-processed: L95012HP1_00086 mask a spike:
msk[w5403,n1,w5408,n1]
The FITS files comply to the standard:
Astrophysics Supplement Series v44/p363, v44/p371, v73/p359, v73/p365.
Each file contains an image extension (EXTNAME=SKY) containing the
sky which was subtracted prior to the flux calibration,
The file names are composed as: DATASET_NNNNN.fits, where DATASET is
the 9 character dataset identifier, and NNNNN a five digit number.
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Acknowledgements: Philippe Prugniel
(End) Philippe Prugniel 12-Jan-2001