J/A+A/567/A71 M31 Herschel images (Viaene+, 2014)
The Herschel Exploitation of Local Galaxy Andromeda (HELGA).
IV. Dust scaling relations at sub-kpc resolution.
Viaene S., Fritz J., Baes M., Bendo G.J., Blommaert J.A.D.L., Boquien M.,
Boselli A., Ciesla L., Cortese L., De Looze I., Gear W.K., Gentile G.,
Hughes T.M., Jarrett T., Karczewski O.L., Smith M.W.L., Spinoglio L.,
Tamm A., Tempel E., Thilker D., Verstappen J.
<Astron. Astrophys. 567, A71 (2014)>
=2014A&A...567A..71V 2014A&A...567A..71V
ADC_Keywords: Galaxies, nearby ; Interstellar medium ;
Photometry, millimetric/submm
Keywords: galaxies: individual: M31 - galaxies: ISM - infrared: ISM -
galaxies: fundamental: parameters - dust, extinction -
methods: observational
Abstract:
Dust and stars play a complex game of interactions in the interstellar
medium and around young stars. The imprints of these processes are
visible in scaling relations between stellar characteristics, star
formation parameters, and dust properties. Aims. In the present work,
we aim to examine dust scaling relations on a sub-kpc resolution in
the Andromeda galaxy (M31). The goal is to investigate the properties
of M31 on both a global and local scale and compare them to other
galaxies of the local universe. Methods. New Herschel observations are
combined with available data from GALEX, SDSS, WISE, and Spitzer to
construct a dataset covering UV to submm wavelengths. All images were
brought to the beam size and pixel grid of the SPIRE 500um frame.
This divides M31 in 22437 pixels of 36 arcseconds in size on the sky,
corresponding to physical regions of 137x608pc in the galaxy's
disk. A panchromatic spectral energy distribution was modelled for
each pixel and maps of the physical quantities were constructed.
Several scaling relations were investigated, focussing on the
interactions of dust with starlight. Results. We find, on a sub-kpc
scale, strong correlations between Mdust/M* and NUV-r, and between
Mdust/M* and mu* (the stellar mass surface density). Striking
similarities with corresponding relations based on integrated galaxies
are found. We decompose M31 in four macro-regions based on their FIR
morphology; the bulge, inner disk, star forming ring, and the outer
disk region. In the scaling relations, all regions closely follow the
galaxy-scale average trends and behave like galaxies of different
morphological types. The specific star formation characteristics we
derive for these macro-regions give strong hints of an inside-out
formation of the bulge-disk geometry, as well as an internal
downsizing process. Within each macro-region, however, a great
diversity in individual micro-regions is found, regardless of the
properties of the macro-regions. Furthermore, we confirm that dust in
the bulge of M31 is heated only by the old stellar populations.
Conclusions. In general, the local dust scaling relations indicate
that the dust content in M31 is maintained by a subtle interplay of
past and present star formation. The similarity with galaxy-based
relations strongly suggests that they are in situ correlations, with
underlying processes that must be local in nature.
Description:
We present new, reduced Herschel Space Observatory PACS and SPIRE 100,
160, 250, 350, and 500 micron observations of M31 taken has part of
the Herschel Exploitation of Local Galaxy Andromeda (P.I.: J. Fritz)
The PACS 100 and 160 observations were reduced with the Herschel
Interactive Processing Environment (HIPE) v.8 and Scanamorphos v.15.0
(Roussel, 2012, ASCL, 1209.012). The SPIRE 250, 350, and 500 micron
observations data were reduced with HIPE v.8 and BriGAdE (Smith, in
preparation). Complete details on the data reduction may be found in
our first paper (Fritz et al., 2012A&A...546A..34F 2012A&A...546A..34F). Image properties
are summarised in images.dat. The raw data can be retrieved from the
Herschel Science Archive (ESA).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
images.dat 76 5 Summary of images
fits/* . 5 Individual FITS images
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See also:
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
J/PASP/122/261 : Herschel Reference Survey Sample (Boselli+, 2010)
Byte-by-byte Description of file: images.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 arcsec Scale [2/12] Image pixel size
23- 27 I5 --- Nx [1953/11485] Number of pixels along X-axis
28 A1 --- --- [x]
29- 33 I5 --- Ny [2149/12830] Number of pixels along Y-axis
35- 40 F6.2 Mibyte size [16/563] Size of FITS file
42- 52 A11 --- Filename Name of the FITS file in subdirectory fits
54- 58 A5 --- Inst Herschel instrument (PACS or SPIRE)
60- 62 I3 um lambda [100/500] Wavelength
64- 67 F4.1 arcsec FWHM [8/37] PSF FWHM
69- 76 A8 --- Units [Jy/pixel] Flux units of images
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Acknowledgements:
Sebastien Viaene, sebastien.viaene(at)ugent.be
References:
Fritz et al., Paper I 2012A&A...546A..34F 2012A&A...546A..34F
Smith et al., Paper II 2012ApJ...756...40S 2012ApJ...756...40S
Ford et al., Papper III 2013ApJ...769...55F 2013ApJ...769...55F
Mattson et al., Paper V 2014MNRAS.444..797M 2014MNRAS.444..797M
Kirk et al., Paper VI 2015ApJ...798...58K 2015ApJ...798...58K Cat. J/ApJ/798/58
(End) Sebastien Viaene [UGent, Belgium], Patricia Vannier [CDS] 06-May-2014