J/A+A/614/A48 Continuous rise of bulges out of galactic disks (Breda+, 2018)
The continuous rise of bulges out of galactic disks.
Breda I., Papaderos P.
<Astron. Astrophys. 614, A48 (2018)>
=2018A&A...614A..48B 2018A&A...614A..48B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs
Keywords: galaxies: spiral - galaxies: bulges - galaxies: evolution
Abstract:
A key subject in extragalactic astronomy concerns the chronology and
driving mechanisms of bulge formation in late-type galaxies (LTGs).
The standard scenario distinguishes between classical bulges and
pseudo-bulges (CBs and PBs, respectively), the first thought to form
monolithically prior to disks and the second gradually out of disks.
These two bulge formation routes obviously yield antipodal predictions
on the bulge age and bulge-to-disk age contrast, both expected to be
high (low) in CBs (PBs).
Our main goal is to explore whether bulges in present-day LTGs
segregate into two evolutionary distinct classes, as expected from the
standard scenario. Other questions motivating this study center on
evolutionary relations between LTG bulges and their hosting disks, and
the occurrence of accretion-powered nuclear activity as a function of
bulge stellar mass M* and stellar surface density Σ*.
In this study we have combined three techniques - surface
photometry, spectral modeling of integral field spectroscopy data and
suppression of stellar populations younger than an adjustable age
cutoff with the code REMOVE YOUNG (RY) - toward a systematic
analysis of the physical and evolutionary properties (e.g., M* ,
Σ* and mass-weighted stellar age <t*>M and metallicity
<Z*>M, respectively) of a representative sample of 135 nearby
(≤130Mpc) LTGs from the CALIFA survey that cover a range between
108.9M☉ and 1011.5M☉ in total stellar mass M*,T. In
particular, the analysis here revolves around <δµ9G>, a new
distance- and formally extinction-independent measure of the
contribution by stellar populations of age ≥9Gyr to the mean r-band
surface brightness of the bulge. We argue that <δµ9Gx > offers
a handy semi-empirical tracer of the physical and evolutionary
properties of LTG bulges and a promising means for their
characterization.
Description:
Photometric, evolutionary and physical quantities for the sample of
late-type galaxies from the CALIFA survey, analyzed in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ltgs.dat 135 135 Photometric, evolutionary and physical quantities
for the galaxy sample under study (table C1)
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See also:
J/A+A/576/A135 : CALIFA DR2 (Garcia-Benito+, 2015)
Byte-by-byte Description of file: ltgs.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Galaxy name (name)
14- 18 F5.1 Mpc Dist Assumed distance (distance)
20- 27 F8.6 kpc RB Isophotal radius of the bulge (BrRiso)
29- 36 F8.5 [Msun] logM*T logarithm of the total stellar mass
(T_logMnow) (1)
38- 45 F8.5 [Msun] logM*B logarithm of the present-day stellar mass
within RB (B_logMnow) (1)
47- 54 F8.5 Gyr <t*B>M Mass-weighted stellar age of the bulge
(B_tMass) (1)
56- 63 F8.6 Gyr s_<t*B>M Dispersion of <t*B>M (BtMassE) (1)
65- 72 F8.5 Gyr <t*D>M Mass-weighted stellar age of the disk
(D_tMass) (1)
74- 81 F8.6 Gyr s_<t*D>M Dispersion of <t*D>M (DtMassE) (1)
83- 90 F8.6 Sun <Z*B>M Mass-weighted stellar metallicity of the
bulge (B_Zmass) (1)
92- 99 F8.6 Sun s_<Z*B>M Dispersion of <Z*B>M (BZmassE) (1)
101-108 F8.6 Sun <Z*D>M Mass-weighted stellar metallicity of the
disk (D_Zmass) (1)
110-117 F8.6 Sun s_<Z*D>M Dispersion of <Z*D>M (DZmassE) (1)
119-125 F7.5 [Msun/kpc2] logS*B logarithm of the mean stellar mass surface
density in the bulge (B_logSSDensity) (1)
127-135 F9.6 mag <md9G> Mean <δµ9G> (rmag) within RB
(DeltaMu_Rb)
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Note (1): Quantities were obtained from spectral modeling with STARLIGHT
of CALIFA V500 data with the Z4 SSP library and refer to the present-day
M* (cf. Sect. 2.2.2).
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Acknowledgements:
Iris Breda, Iris.Breda(at)astro.up.pt
(End) Patricia Vannier [CDS] 28-Dec-2017