J/MNRAS/489/5030 Star formation in Milky Way analogues (Fraser-McKelvie+, 2019)
From the outside looking in: what can Milky Way analogues tell us about the
star formation rate of our own galaxy?
Fraser-McKelvie A., Merrifield M., Aragon-Salamanca A.
<Mon. Not. R. Astron. Soc., 489, 5030-5036 (2019)>
=2019MNRAS.489.5030F 2019MNRAS.489.5030F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Galaxies, spectra ; Milky Way ; Optical ;
Infrared
Keywords: Galaxy: general - galaxies: evolution - galaxies: general -
galaxies: spiral - galaxies: star formation
Abstract:
The Milky Way has been described as an anaemic spiral, but is its star
formation rate (SFR) unusually low when compared to its peers? To
answer this question, we define a sample of Milky Way analogues (MWAs)
based on stringent cuts on the best literature estimates of
non-transient structural features for the Milky Way. This selection
yields only 176 galaxies from the whole of the SDSS DR7 spectroscopic
sample which have morphological classifications in Galaxy Zoo 2, from
which we infer SFRs from two separate indicators. The mean SFRs found
are log(SFRSED/M☉yr-1)=0.53 with a standard deviation of
0.23dex from SED fits, and log(SFRW4/M☉yr-1)=0.68 with a
standard deviation of 0.41dex from a mid-infrared calibration. The
most recent estimate for the Milky Way's SFR of
log(SFRMW/M☉yr-1)=0.22 fits well within 2σ of these
values, where σ is the standard deviation of each of the SFR
indicator distributions. We infer that the Milky Way, while being a
galaxy with a somewhat low SFR, is not unusual when compared to
similar galaxies.
Description:
To create a sample of Milky Way Analogues (MWAs), we team a tight
constraint on stellar mass with three structural parameters that are
well-determined for the Milky Way: the presence of spiral arms, a bar,
and a small bulge. Only a galaxy satisfying all four criteria will be
termed an MWA. The parent sample is the Sloan Digital Sky Survey Data
Release 7 (SDSS DR7; Abazajian et al. 2009ApJS..182..543A 2009ApJS..182..543A, Cat.
II/294).
For the spiral and bar classifications, we used the Galaxy Zoo 2 (GZ2;
Willett et al. 2013MNRAS.435.2835W 2013MNRAS.435.2835W, J/MNRAS/435/2835) citizen science
project. For the spiral arms, we imposed the spiral weighted fraction
to be >0.7. For the bar, we selected the galaxies having a bar
weighted fraction >0.5. Then, we adopted bulge-to-total ratio (BTR)
from Simrad et al. (2011ApJS..196...11S 2011ApJS..196...11S, Cat. J/ApJS/196/11) and
selected galaxies with 0.1<BTR<0.2. Finally, we employed the
NASA-Sloan Atlas (NSA) catalogue (Blanton et al. 2011AJ....142...31B 2011AJ....142...31B)
masses derived from elliptical Petrosian photometry and keeped only
the galaxies having 4.1x1010M☉<M<8.0x1010^M☉.
By incorporating the extremely strict structural criteria listed
above, we end up with a well-defined sample of 176 galaxies in SDSS
DR7.
We take a multiwavelength approach to calculating SFRs of the MWAs,
using both UV/Optical/mid-IR spectral energy distributions (SEDs), and
as a cross-check, a mid-infrared (IR) indicator calibrated to total-IR
luminosity. Given these SFR indicators employ contrasting techniques,
and overlapping but not identical wavelength ranges, they are
complementary to one another. We list all MWAs in the sample, along
with their SFRs, in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 176 Table of the MWAs and their derived SFRs from
this work
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See also:
II/294 : The SDSS Photometric Catalog, Release 7
(Adelman-McCarthy+, 2009)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/MNRAS/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Name Galaxy name
24- 30 F7.3 deg RAdeg Right ascension (J2000)
32- 37 F6.3 deg DEdeg Declination (J2000)
39- 43 F5.2 [Msun/yr] logSFRSED ? Logarithm of SED-derived star formation
rate (1)
45- 49 F5.2 [Msun/yr] logSFRW3 ? Logarithm of the star formation rate
derived using WISE W3 (2)
51- 55 F5.2 [Msun/yr] logSFRW4 ? Logarithm of the star formation rate
derived using WISE W4 (2)
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Note (1): When no SED-derived SFR is listed, this value is missing from the
Salim et al. (2018ApJ...859...11S 2018ApJ...859...11S) catalogue
Note (2): When no W3 or W4 SFR is listed, WISE photometry was not available for
this galaxy in the AllWISE source catalogue, usually due to the
automated pipeline splitting a single nearby galaxy into two separate
sources
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 18-Jan-2023