J/AJ/163/14 Galactic extinction near external galaxies (Brown+, 2022)
Galaxian Contamination in Galactic Reddening Maps.
Brown P.J., Walker T.
<Astron. J., 163, 14 (2022)>
=2022AJ....163...14B 2022AJ....163...14B
ADC_Keywords: Galaxies; Interstellar medium; Extinction; Infrared; Supernovae
Keywords: Interstellar dust extinction ; Milky Way Galaxy ; Infrared
Astronomical Satellite ; Galaxies ; Supernovae
Abstract:
Estimating the amount of foreground extinction due to the Milky Way
dust along the line of sight is often a first step in determining the
luminosity of an object. The amount of Galactic dust inferred by
infrared emission maps can be contaminated by infrared light from
nearby galaxies. By comparing extinction values at and around the
location of nearby galaxies, we compile a list of 95 galaxies that
likely contaminate the maps with an excess or improperly subtracted
galaxian infrared emission, and tabulate our recommended values for
the MW contribution. In addition to M82, which inspired this work, six
more sources have an excess visual extinction A V of at least 0.05mag
greater than our annular values; including M83, NGC1313, NGC6822,
NGC918, UGC11501, and UGC11797. M33 is shown to be oversubtracted.
NGC88 and the outskirts of NGC4258 are located in gaps in the Infrared
Astronomical Satellite imaging. The recommended dust map values for
the LMC, SMC, and M31 may also not be correctly returned by some
software packages. Accurate reddening estimates are important for
measuring stellar and supernova luminosities in these nearby galaxies.
Description:
We have searched for galaxies whose infrared emission might
significantly contaminate the Infrared Astronomical Satellite (IRAS)
images resulting in a overestimate of the foreground MW dust
reddening. We provide a table of such galaxies, their coordinates, our
recommended values on the Schlafly+, 2011ApJ...737..103S 2011ApJ...737..103S system, and
the radius with which to use replacement values from those looked up
by default from the SFD98 maps via NED or Astroquery (Ginsburg+,
2019AJ....157...98G 2019AJ....157...98G).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 179 96 *Improved estimates for the galactic extinction in
the line of sight near external galaxies
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Note on table1.dat : In the Schlafly+, 2011ApJ...737..103S 2011ApJ...737..103S system.
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See also:
VII/109 : IRAS Observations of Large Optical Galaxies (Rice+, 1988)
J/ApJ/652/1133 : BVI photometry of NGC 4258 Cepheids (Macri+, 2006)
J/ApJ/697/1138 : Discovery of PNe in M82 (Johnson+, 2009)
J/ApJ/830/10 : >20yrs of HST obs. Cepheids SNIa host gal. (Hoffmann+, 2016)
J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Name Galaxy Name
25- 26 I2 h RAh [0/23] Hour of Right Ascension (J2000)
28- 29 I2 min RAm Minute of Right Ascension (J2000)
31- 37 F7.4 s RAs Second of Right Ascension (J2000)
39- 39 A1 --- DE- [±] Sign of the Declination (J2000)
40- 41 I2 deg DEd Degree of Declination (J2000)
43- 44 I2 arcmin DEm Arcminute of Declination (J2000)
46- 52 F7.4 arcsec DEs Arcsecond of Declination (J2000)
54- 56 I3 arcmin Rad [5/323] Galaxy radius
58- 63 F6.4 mag AVmag [0.02/1.95] Estimate, V-band Galactic
Extinction in the Line of Sight
65- 65 A1 --- f_AVmag Flag on AVmag (1)
67- 71 F5.3 mag e_AVmag [0.001/0.1] Uncertainty on AVmag (2)
73-179 A107 --- SNe Comma separated list of Supernovae/Transients
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Note (1): Flags as follows:
b = Value from Appendix C of Schlegel+, 1998ApJ...500..525S 1998ApJ...500..525S converted to
the Schlafly+, 2011ApJ...737..103S 2011ApJ...737..103S system
c = Value from Dalcanton+, 2009ApJS..183...67D 2009ApJS..183...67D converted to the
Schlafly+, 2011ApJ...737..103S 2011ApJ...737..103S system.
Note (2): This is the uncertainty on what the extinction would be from the
Schlegel+, 1998ApJ...500..525S 1998ApJ...500..525S maps converted to the
Schlafly+, 2011ApJ...737..103S 2011ApJ...737..103S system. It does not include the overall
16% uncertainty of the maps themselves quoted by
Schlegel+, 1998ApJ...500..525S 1998ApJ...500..525S which should be added in quadrature.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 28-Mar-2022