J/MNRAS/498/4943 Milky Way and Andromeda analogues (Boardman+, 2020)
Are the Milky Way and Andromeda unusual? A comparison with Milky Way and
Andromeda analogues.
Boardman N., Zasowski G., Newman J.A., Andrews B., Fielder C., Bershady M.,
Brinkmann J., Drory N., Krishnarao D., Lane R.R., Mackereth T., Masters K.,
Stringfellow G.S.
<Mon. Not. R. Astron. Soc., 498, 4943-4954 (2020)>
=2020MNRAS.498.4943B 2020MNRAS.498.4943B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Redshifts ; Positional data ; Star Forming Region ;
Ultraviolet ; Optical ; Infrared
Keywords: galaxies: general - galaxies: spiral - galaxies: statistics -
galaxies: stellar content - galaxies: structure - Galaxy: general
Abstract:
Our Milky Way provides a unique test case for galaxy evolution models
because of our privileged position within the Milky Way's disc. This
position also complicates comparisons between the Milky Way and
external galaxies, due to our inability to observe the Milky Way from
an external point of view. Milky Way analogue galaxies offer us a
chance to bridge this divide by providing the external perspective
that we otherwise lack. However, overprecise definitions of 'analogue'
yield little-to-no galaxies, so it is vital to understand which
selection criteria produce the most meaningful analogue samples. To
address this, we compare the properties of complementary samples of
Milky Way analogues selected using different criteria. We find the
Milky Way to be within 1σ of its analogues in terms of star
formation rate and bulge-to-total ratio in most cases, but we find
larger offsets between the Milky Way and its analogues in terms of
disc scale length; this suggests that scale length must be included in
analogue selections in addition to other criteria if the most accurate
analogues are to be selected. We also apply our methodology to the
neighbouring Andromeda galaxy. We find analogues selected on the basis
of strong morphological features to display much higher star formation
rates than Andromeda, and we also find analogues selected on
Andromeda's star formation rate to overpredict Andromeda's bulge
extent. This suggests both structure and star formation rate should be
considered when selecting the most stringent Andromeda analogues.
Description:
We obtain total stellar masses and current global SFRs from the Galaxy
Evolution Explorer (GALEX)-SDSS-WISE Legacy catalogue (GSWLC; Salim et
al. 2016ApJS..227....2S 2016ApJS..227....2S), employing the GSWLC-2X catalogue (Salim,
Boquien & Lee 2018ApJ...859...11S 2018ApJ...859...11S). GSWLC-2X contains stellar masses
and SFRs for 659229 galaxies, selected by cross-referencing the
spectroscopic SDSS Data Release 10 (DR10; Ahn et al.
2014ApJS..211...17A 2014ApJS..211...17A) sample with the ultraviolet GALEX (Martin et al.
2005ApJ...619L...1M 2005ApJ...619L...1M) sample. The GSWLC masses and SFRs assume a
Chabrier (2003PASP..115..763C 2003PASP..115..763C) initial mass function (IMF); we
converted these to a Kroupa (2001MNRAS.322..231K 2001MNRAS.322..231K) IMF by multiplying
by a factor of 1.06 (Elbaz et al. 2007A&A...468...33E 2007A&A...468...33E; Salim et al.
2007ApJS..173..267S 2007ApJS..173..267S; Zahid et al. 2012ApJ...757...54Z 2012ApJ...757...54Z).
We obtain light-weighted r-band B/T and Rd values from the catalogue
of Simard et al. (2011ApJS..196...11S 2011ApJS..196...11S, Cat. J/ApJS/196/11), who
perform bulge-disc decompositions of 1123718 galaxies from the SDSS
Data Release 7 (DR7; Abazajian et al. 2009ApJS..182..543A 2009ApJS..182..543A, Cat.
II/294).
We obtain redshifts and absolute magnitudes from version 1.0.1 of the
NASA-Sloan Atlas (NSA) catalogue (Blanton et al.
2011AJ....142...31B 2011AJ....142...31B), which re-reduces the data in SDSS Data Release 8
(DR8; Aihara et al. 2011ApJS..193...29A 2011ApJS..193...29A).
Finally, we obtain measurements of galaxy morphologies from the Galaxy
Zoo 2 catalogue (GZ2; Willett et al. 2013MNRAS.435.2835W 2013MNRAS.435.2835W, Cat.
J/MNRAS/435/2835), employing user-weighted vote fractions along with
the redshift-debiased fractions described in Hart et al.
(2016MNRAS.461.3663H 2016MNRAS.461.3663H, Cat. J/MNRAS/461/3663).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 125 2688 Table of Milky Way Analogues, with no redshift
cut applied
table4.dat 123 1321 Table of Andromeda Analogues, with no redshift
cut applied
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See also:
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
II/294 : The SDSS Photometric Catalog, Release 7
(Adelman-McCarthy+, 2009)
V/139 : The SDSS Photometric Catalog, Release 9
(Adelman-McCarthy+, 2012)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID SDSS DR8 object identifier
21- 29 F9.5 deg RAdeg Right ascension (J2000)
31- 42 F12.9 deg DEdeg Declination (J2000)
44- 54 F11.9 --- z Redshift
56- 64 F9.6 [Msun] logM* Logarithm of the stellar mass
66- 79 F14.11 [Msun/yr] logSFR Logarithm of the star formation rate
81- 89 F9.7 --- B/T Bulge-to-total ratio
91- 98 F8.5 kpc Rd Disc scale length
100- 111 F12.10 --- Spiral Spiral vote fraction
113- 123 F11.9 --- Bar Bar vote fraction
125 I1 --- Flag [0/1] Flag indicating the galaxy's status
as a morphological Milky Way Analogue
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- ID SDSS DR8 object identifier
21- 29 F9.5 deg RAdeg Right ascension (J2000)
31- 42 F12.9 deg DEdeg Declination (J2000)
44- 54 F11.9 --- z Redshift
56- 64 F9.6 [Msun] logM* Logarithm of the stellar mass
66- 78 F13.10 [Msun/yr] logSFR Logarithm of the star formation rate
80- 88 F9.7 --- B/T Bulge-to-total ratio
90- 97 F8.5 kpc Rd Disc scale length
99- 109 F11.9 --- Spiral Spiral vote fraction
111- 121 F11.9 --- Bar Bar vote fraction
123 I1 --- Flag [0/1] Flag indicating the galaxy's status
as a morphological Andromeda analogue
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 09-Aug-2023