140 research outputs found
Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs
We study dust attenuation curves of 230,000 individual galaxies in the local
universe, ranging from quiescent to intensely star-forming systems, using
GALEX, SDSS, and WISE photometry calibrated on Herschel-ATLAS. We use a new
method of constraining SED fits with infrared luminosity (SED+LIR fitting), and
parameterized attenuation curves determined with the CIGALE SED fitting code.
Attenuation curve slopes and UV bump strengths are reasonably well constrained
independently from one another. We find that attenuation
curves exhibit a very wide range of slopes that are on average as steep as the
SMC curve slope. The slope is a strong function of optical opacity. Opaque
galaxies have shallower curves - in agreement with recent radiate transfer
models. The dependence of slopes on the opacity produces an apparent dependence
on stellar mass: more massive galaxies having shallower slopes. Attenuation
curves exhibit a wide range of UV bump amplitudes, from none to MW-like; with
an average strength 1/3 of the MW bump. Notably, local analogs of high-redshift
galaxies have an average curve that is somewhat steeper than the SMC curve,
with a modest UV bump that can be to first order ignored, as its effect on the
near-UV magnitude is 0.1 mag. Neither the slopes nor the strengths of the UV
bump depend on gas-phase metallicity. Functional forms for attenuation laws are
presented for normal star-forming galaxies, high-z analogs and quiescent
galaxies. We release the catalog of associated SFRs and stellar masses
(GSWLC-2).Comment: Accepted to ApJ. GSWLC-2 catalog of SED+LIR SFRs and M* to be
released Jun 1 at http://pages.iu.edu/~salims/gswlc
DustKING - the story continues: dust attenuation in NGC628
Dust attenuation is a crucial but highly uncertain parameter that hampers the
determination of intrinsic galaxy properties, such as stellar masses, star
formation rates and star formation histories. The shape of the dust attenuation
law is not expected to be uniform between galaxies, nor within a galaxy. Our
DustKING project was introduced at the first BINA workshop in 2016 and aims to
study the variations of dust attenuation curves in nearby galaxies. At the
second BINA workshop in 2018, I presented the results of our pilot study for
the spiral galaxy NGC628. We find that the average attenuation law of this
galaxy is characterised by a MW-like bump and a steep UV slope. Furthermore, we
observe intriguing variations within the galaxy, with regions of high
exhibiting a shallower attenuation curve. Finally, we discuss how our work
might benefit from data taken with the UVIT from the Indian AstroSat mission.Comment: 8 pages, 6 figures, Proceedings paper of the second Belgo-Indian
Network for Astronomy & astrophysics (BINA) workshop, accepted for
publication in the Bulletin de la Soci\'et\'e Royale des Sciences de Li\`eg
DustKING, the story continues : dust attenuation in NGC 628
Dust attenuation is a crucial but highly uncertain parameter that hampers the determination of in- trinsic galaxy properties, such as stellar masses, star formation rates and star formation histories. The shape of the dust attenuation law is not expected to be uniform between galaxies, nor within a galaxy. Our DustKING project was introduced at the first BINA workshop in 2016 and aims to study the variations of dust attenuation curves in nearby galaxies. At the second BINA workshop in 2018, I presented the results of our pilot study for the spiral galaxy NGC 628. We find that the average attenuation law of this galaxy is characterised by a MW-like bump and a steep UV slope. Furthermore, we observe intriguing variations within the galaxy, with regions of high AV exhibiting a shallower attenuation curve. Finally, we discuss how our work might benefit from data taken with the UVIT from the Indian AstroSat mission
Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs
We study the dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using GALEX, SDSS, and WISE photometry calibrated on the Herschel ATLAS. We use a new method of constraining SED fits with infrared luminosity (SED+LIR fitting), and parameterized attenuation curves determined with the CIGALE SED-fitting code. Attenuation curve slopes and UV bump strengths are reasonably well constrained independently from one another. We find that A_λ/A_V attenuation curves exhibit a very wide range of slopes that are on average as steep as the curve slope of the Small Magellanic Cloud (SMC). The slope is a strong function of optical opacity. Opaque galaxies have shallower curves—in agreement with recent radiative transfer models. The dependence of slopes on the opacity produces an apparent dependence on stellar mass: more massive galaxies have shallower slopes. Attenuation curves exhibit a wide range of UV bump amplitudes, from none to Milky Way (MW)-like, with an average strength one-third that of the MW bump. Notably, local analogs of high-redshift galaxies have an average curve that is somewhat steeper than the SMC curve, with a modest UV bump that can be, to first order, ignored, as its effect on the near-UV magnitude is 0.1 mag. Neither the slopes nor the strengths of the UV bump depend on gas-phase metallicity. Functional forms for attenuation laws are presented for normal star-forming galaxies, high-z analogs, and quiescent galaxies. We release the catalog of associated star formation rates and stellar masses (GALEX–SDSS–WISE Legacy Catalog 2)
Spectral Energy Distributions of a set of HII regions in M33 (HerM33es)
Within the framework of the HerM33es Key Project for Herschel and in
combination with multi-wavelength data, we study the Spectral Energy
Distribution (SED) of a set of HII regions in the Local Group Galaxy M33. Using
the Halpha emission, we perform a classification of a selected HII region
sample in terms of morphology, separating the objects in filled, mixed, shell
and clear shell objects. We obtain the SED for each HII region as well as a
representative SED for each class of objects. We also study the emission
distribution of each band within the regions. We find different trends in the
SEDs for each morphological type that are related to properties of the dust and
their associated stellar cluster. The emission distribution of each band within
the region is different for each morphological type of object.Comment: 3pages, 4 figures. To appear in 'The Spectral Energy Distribution of
Galaxies' Proceedings IAU Symposium No 284, 201
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