648 research outputs found
Is it easy for producers to market organic beef meat ? The case of Biobourgogne Viande (France).
This contribution aims to present the results of a French case-study analysis - BioBourgogne Viande - carried up by members of three research teams in the framework of the European Program OMIaRD (Organic Marketing Initiatives and Rural Development) .
In a first part, after a brief description of the region where the O.M.I is located, we present the main features of the development of BioBourgogne Viande, from its origins to the present day. In a second part, the motivations, cohesion and competencies are analysed in the structure of a SWOT (opportunities, threats, strengths and weaknesses), identifying organisational learning processes through the past ten year
Extended mid-infrared emission from VV 114: probing the birth of a ULIRG
We present our 5-16 micron spectro-imaging observations of VV114, an infrared
luminous early-stage merger, taken with the ISOCAM camera on-board ISO. We find
that only 40% of the mid-infrared (MIR) flux is associated with a compact
nuclear region, while the rest of the emission originates from a rather diffuse
component extended over several kpc. This is in stark contrast with the very
compact MIR starbursts usually seen in luminous infrared galaxies. A secondary
peak of MIR emission is associated with an extra-nuclear star forming region
which displays the largest Halpha equivalent width in the whole system.
Comparing our data with the distribution of the molecular gas and cold dust, as
well as with radio observations, it becomes evident that the conversion of
molecular gas into stars can be triggered over large areas at the very first
stages of an interaction. The presence of a very strong continuum at 5 microns
in one of the sources indicates that an enshrouded active galactic nucleus may
contribute to 40% of its MIR flux. We finally note that the relative variations
in the UV to radio spectral properties between the merging galaxies provide
evidence that the extinction-corrected star formation rate of similar objects
at high z, such as those detected in optical deep surveys, can not be
accurately derived from their rest-frame UV properties.Comment: 14 pages, 5 figures, accepted for publication in A&
The PEP Survey: Infrared Properties of Radio-Selected AGN
By exploiting the VLA-COSMOS and the Herschel-PEP surveys, we investigate the
Far Infrared (FIR) properties of radio-selected AGN. To this purpose, from
VLA-COSMOS we considered the 1537, F[1.4 GHz]>0.06 mJy sources with a reliable
redshift estimate, and sub-divided them into star-forming galaxies and AGN
solely on the basis of their radio luminosity. The AGN sample is complete with
respect to radio selection at all z<~3.5. 832 radio sources have a counterpart
in the PEP catalogue. 175 are AGN. Their redshift distribution closely
resembles that of the total radio-selected AGN population, and exhibits two
marked peaks at z~0.9 and z~2.5. We find that the probability for a
radio-selected AGN to be detected at FIR wavelengths is both a function of
radio power and redshift, whereby powerful sources are more likely to be FIR
emitters at earlier epochs. This is due to two distinct effects: 1) at all
radio luminosities, FIR activity monotonically increases with look-back time
and 2) radio activity of AGN origin is increasingly less effective at
inhibiting FIR emission. Radio-selected AGN with FIR emission are
preferentially located in galaxies which are smaller than those hosting
FIR-inactive sources. Furthermore, at all z<~2, there seems to be a
preferential (stellar) mass scale M ~[10^{10}-10^{11}] Msun which maximizes the
chances for FIR emission. We find such FIR (and MIR) emission to be due to
processes indistinguishable from those which power star-forming galaxies. It
follows that radio emission in at least 35% of the entire AGN population is the
sum of two contributions: AGN accretion and star-forming processes within the
host galaxy.Comment: 13 pages, 14 figures, to appear in MNRA
Mid-infrared observations of the ultraluminous galaxies IRAS14348-1447, IRAS19254-7245, and IRAS23128-5919
We present a study of the three ultraluminous infrared galaxies
IRAS14348-1447, IRAS19254-7245, and IRAS23128-5919, based on mid-infrared (MIR)
spectro-imaging (5-18microns) observations performed with ISOCAM. We find that
the MIR emission from each system, which consists of a pair of interacting late
type galaxies, is principally confined to the nuclear regions with diameters of
1-2kpc and can account for more than 95% of their IRAS 12micron flux. In each
interacting system, the galaxy hosting an active galactic nucleus (AGN)
dominates the total spectrum and shows stronger dust continuum (12-16microns)
relative to the Unidentified Infrared Band (UIB) emission (6-9microns),
suggestive of its enhanced radiation field. The MIR dominant galaxy also
exhibits elevated 15micron/Halpha and 15micron/K ratios which trace the high
extinction due to the large quantities of molecular gas and dust present in its
central regions. Using only diagnostics based on our mid-infrared spectra, we
can establish that the Seyfert galaxy IRAS19254-7245 exhibits MIR spectral
features of an AGN while the MIR spectrum of the Seyfert (or LINER) member of
IRAS23128-5919 is characteristic of dust emission principally heated by star
forming regions.Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 9
figure
Morphological Classification of Local Luminous Infrared Galaxies
We present an analysis of the morphological classification of 89 luminous
infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey
(GOALS) sample using non-parametric coefficients and compare their morphology
as a function of wavelength. We rely on images obtained in the optical (B- and
I-band) as well as in the infrared (H-band and 5.8m). Our classification
is based on the calculation of and the second order of light ()
non-parametric coefficients which we explore as a function of stellar mass
(), infrared luminosity () and star formation rate (SFR). We
investigate the relation between , the specific SFR (sSFR) and the dust
temperature () in our galaxy sample. We find that is a
better morphological tracer than , as it allows to distinguish systems
formed by double systems from isolated and post-merger LIRGs. The
multi-wavelength analysis allows us to identify a region in the -
parameter space where ongoing mergers reside, regardless of the band used to
calculate the coefficients. In particular when measured in the H-band, this
region can be used to identify ongoing mergers, with a minimal contamination
from LIRGs in other stages. We also find that while the sSFR is positively
correlated with when measured in the mid-infrared, i.e. star-bursting
galaxies show more compact emission, it is anti-correlated with the B-band
based . We interpret this as the spatial decoupling between obscured
and un-obscured star formation, whereby the ultraviolet/optical size of a LIRGs
experience an intense dust enshrouded central starburst is larger than in the
one in the mid-infrared since the contrast between the nuclear to the extended
disk emission is smaller in the mid-infrared. This has important implications
for high redshift surveys of dusty sources. [abridged]Comment: ( 18 pages, 12 figures, Accepted for publication in A&A
A bias in optical observations of high redshift luminous infrared galaxies
We present evidence for the dramatically different morphology between the
rest frame UV and 7micron mid-IR emission of VV114 and Arp299, two nearby (z~0)
violently interacting infrared luminous galaxies (LIRGs). Nearly all LIRGs are
interacting systems and it is currently accepted that they dominate the IR
emission at z>1. Luminous IR galaxies located at z=1-2 could easily be detected
as unresolved sources in deep optical/near-IR ground based surveys, as well as
in upcoming 24micron surveys with the Space Infrared Telescope Facility. We
demonstrate that the spatial resolution of these surveys will result in
blending of the emission from unresolved interacting components. An increased
scatter will thus be introduced in the observed optical to mid-IR colors of
these galaxies, leading to a systematic underestimation of their dust content.Comment: To appear in the Astrophysical Journal Letters (4 pages 1 figure
The FUV to Near-IR Morphologies of Luminous Infrared Galaxies in the GOALS Sample
We compare the morphologies of a sample of 20 LIRGs from the Great
Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I and H bands, using
the Gini (G) and M20 parameters to quantitatively estimate the distribution and
concentration of flux as a function of wavelength. HST images provide an
average spatial resolution of ~80 pc. While our LIRGs can be reliably
classified as mergers across the entire range of wavelengths studied here,
there is a clear shift toward more negative M20 (more bulge-dominated) and a
less significant decrease in G values at longer wavelengths. We find no
correlation between the derived FUV G-M20 parameters and the global measures of
the IR to FUV flux ratio, IRX. Given the fine resolution in our HST data, this
suggests either that the UV morphology and IRX are correlated on very small
scales, or that the regions emitting the bulk of the IR emission emit almost no
FUV light. We use our multi-wavelength data to simulate how merging LIRGs would
appear from z~0.5-3 in deep optical and near-infrared images such as the HUDF,
and use these simulations to measure the G-M20 at these redshifts. Our
simulations indicate a noticeable decrease in G, which flattens at z >= 2 by as
much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the
rest-frame FUV. The higher redshift values of M20 for the GOALS sources do not
appear to change more than about 10% from the values at z~0. The change in
G-M20 is caused by the surface brightness dimming of extended tidal features
and asymmetries, and also the decreased spatial resolution which reduced the
number of individual clumps identified. This effect, seen as early as z~0.5,
could easily lead to an underestimate of the number of merging galaxies at
high-redshift in the rest-frame FUV.Comment: Accepted for publication in the Astronomical Journal. The total page
count is 15 pages with 13 figures and 1 Tabl
The radio properties of optically obscured Spitzer sources
This paper analyses the radio properties of a subsample of optically obscured
(R>25.5) galaxies observed at 24um by the Spitzer Space Telescope within the
First Look Survey. 96 F[24um]>0.35 mJy objects out of 510 are found to have a
radio counterpart at 1.4 GHz, 610 MHz or at both frequencies respectively down
to ~40uJy and ~200uJy. IRAC photometry sets the majority of them in the
redshift interval z [1-3] and allows for a broad distinction between
AGN-dominated galaxies (~47% of the radio-identified sample) and systems
powered by intense star-formation (~13%), the remaining objects being
impossible to classify. The percentage of radio identifications is a strong
function of 24um flux. The radio number counts at both radio frequencies
suggest that the physical process(es) responsible for radio activity in these
objects have a common origin regardless of whether the source shows mid-IR
emission compatible with being an obscured AGN or a star-forming galaxy. We
also find that both candidate AGN and star-forming systems follow (although
with a large scatter) the relationship between 1.4 GHz and 24um fluxes reported
by Appleton et al. (2004) which identifies sources undergoing intense star
formation activity. On the other hand, the inferred radio spectral indices
alpha indicate that a large fraction of objects in our sample (~60% of all
galaxies with estimated alpha) may belong to the population of Ultra Steep
Spectrum (USS) Sources, typically 'frustrated' radio-loud AGN. We interpret our
findings as a strong indication for concurrent AGN and star-forming activity,
whereby the 1.4 GHz flux is of thermal origin, while that at 610 GHz mainly
stems from the nuclear source.Comment: 18 pages, 16 figures, to appear in MNRA
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