16 research outputs found
IAS/CEA Evolution of Dust in Nearby Galaxies (ICED): the spatially-resolved dust properties of NGC4254
We present the first preliminary results of the project \textit{ICED},
focusing on the face-on galaxy NGC4254. We use the millimetre maps observed
with NIKA2 at IRAM-30m, as part of the IMEGIN Guaranteed Time Large Program,
and of a wide collection of ancillary data (multi-wavelength photometry and gas
phase spectral lines) that are publicly available. We derive the global and
local properties of interstellar dust grains through infrared-to-radio spectral
energy distribution fitting, using the hierarchical Bayesian code HerBIE, which
includes the grain properties of the state-of-the-art dust model, THEMIS. Our
method allows us to get the following dust parameters: dust mass, average
interstellar radiation field, and fraction of small grains. Also, it is
effective in retrieving the intrinsic correlations between dust parameters and
interstellar medium properties. We find an evident anti-correlation between the
interstellar radiation field and the fraction of small grains in the centre of
NGC4254, meaning that, at strong radiation field intensities, very small
amorphous carbon grains are efficiently destroyed by the ultra-violet photons
coming from newly formed stars, through photo-desorption and sublimation. We
observe a flattening of the anti-correlation at larger radial distances, which
may be driven by the steep metallicity gradient measured in NGC4254.Comment: to appear in Proc. of the mm Universe 2023 conference, Grenoble
(France), June 2023, published by F. Mayet et al. (Eds), EPJ Web of
conferences, EDP Science
Exploring the interstellar medium of NGC 891 at millimeter wavelengths using the NIKA2 camera
In the framework of the IMEGIN Large Program, we used the NIKA2 camera on the
IRAM 30-m telescope to observe the edge-on galaxy NGC 891 at 1.15 mm and 2 mm
and at a FWHM of 11.1" and 17.6", respectively. Multiwavelength data enriched
with the new NIKA2 observations fitted by the HerBIE SED code (coupled with the
THEMIS dust model) were used to constrain the physical properties of the ISM.
Emission originating from the diffuse dust disk is detected at all wavelengths
from mid-IR to mm, while mid-IR observations reveal warm dust emission from
compact HII regions. Indications of mm excess emission have also been found in
the outer parts of the galactic disk. Furthermore, our SED fitting analysis
constrained the mass fraction of the small (< 15 Angstrom) dust grains. We
found that small grains constitute 9.5% of the total dust mass in the galactic
plane, but this fraction increases up to ~ 20% at large distances (|z| > 3 kpc)
from the galactic plane.Comment: To appear in Proc. of the mm Universe 2023 conference, Grenoble
(France), June 2023, published by F. Mayet et al. (Eds), EPJ Web of
conferences, EDP Science
Sources of variation for indoor nitrogen dioxide in rural residences of Ethiopia
<p>Abstract</p> <p>Background</p> <p>Unprocessed biomass fuel is the primary source of indoor air pollution (IAP) in developing countries. The use of biomass fuel has been linked with acute respiratory infections. This study assesses sources of variations associated with the level of indoor nitrogen dioxide (NO<sub>2</sub>).</p> <p>Materials and methods</p> <p>This study examines household factors affecting the level of indoor pollution by measuring NO<sub>2</sub>. Repeated measurements of NO<sub>2 </sub>were made using a passive diffusive sampler. A <it>Saltzman </it>colorimetric method using a spectrometer calibrated at 540 nm was employed to analyze the mass of NO<sub>2 </sub>on the collection filter that was then subjected to a mass transfer equation to calculate the level of NO<sub>2 </sub>for the 24 hours of sampling duration. Structured questionnaire was used to collect data on fuel use characteristics. Data entry and cleaning was done in EPI INFO version 6.04, while data was analyzed using SPSS version 15.0. Analysis of variance, multiple linear regression and linear mixed model were used to isolate determining factors contributing to the variation of NO<sub>2 </sub>concentration.</p> <p>Results</p> <p>A total of 17,215 air samples were fully analyzed during the study period. Wood and crop were principal source of household energy. Biomass fuel characteristics were strongly related to indoor NO<sub>2 </sub>concentration in one-way analysis of variance. There was variation in repeated measurements of indoor NO<sub>2 </sub>over time. In a linear mixed model regression analysis, highland setting, wet season, cooking, use of fire events at least twice a day, frequency of cooked food items, and interaction between ecology and season were predictors of indoor NO<sub>2 </sub>concentration. The volume of the housing unit and the presence of kitchen showed little relevance in the level of NO<sub>2 </sub>concentration.</p> <p>Conclusion</p> <p>Agro-ecology, season, purpose of fire events, frequency of fire activities, frequency of cooking and physical conditions of housing are predictors of NO<sub>2 </sub>concentration. Improved kitchen conditions and ventilation are highly recommended.</p
IAS/CEA Evolution of Dust in Nearby Galaxies (ICED): The spatially-resolved dust properties of NGC4254
We present the first preliminary results of the project ICED, focusing on the face-on galaxy NGC4254. We use the millimetre maps observed with NIKA2 at lRAM-30m. as part of the IMEGIN Guaranteed Time Large Program. and of a wide collection of ancillary data (multi-wavelength photometry and gas phase spectral lines) that are publicly available. We derive the global and local properties of interstellar dust grains through infrared-to-radio spectral energy distribution fitting, using the hierarchical Bayesian code HerBIE. which includes the grain properties of the state-of-the-art dust model. THEMIS. Our method allows us to get the following dust parameters: dust mass, average interstellar radiation field, and fraction of small grains. Also, it is effective in retrieving the intrinsic correlations between dust parameters and interstellar medium properties. We find an evident anti-correlation between the interstellar radiation field and the fraction of small grains in the centre of NGC4254. meaning that, at strong radiation field intensities, very small amorphous carbon grains are efficiently destroyed by the ultra-violet photons coming from newly formed stars, through photo-desorption and sublimation. We observe a flattening of the anti-correlation at larger radial distances, which may be driven by the steep metallicity gradient measured in NGC4254
Chemical exchange in tissue extracts revisited : Bicarbonate and deuterium isotope effects on 31P resonances of phosphoethanolamine and phosphocreatine
NRC publication: Ye
The stratification of ISM properties in the edge-on galaxy NGC 891 revealed by NIKA2
15 pages, 10 figures, Accepted for publication in A&AInternational audienceAs the millimeter wavelength range remains a largely unexplored spectral region for galaxies, the IMEGIN large program aims to map the millimeter continuum emission of 22 nearby galaxies at 1.15 and 2 mm. Using the high-resolution maps produced by the NIKA2 camera, we explore the existence of very cold dust and take possible contamination by free-free and synchrotron emission into account. We study the IR-to-radio emission coming from different regions along the galactic plane and at large vertical distances. New observations of NGC 891, using the NIKA2 camera on the IRAM 30m telescope, along with a suite of observations at other wavelengths were used to perform a multiwavelength study of the spectral energy distribution in the interstellar medium in this galaxy. This analysis was performed globally and locally, using the advanced hierarchical Bayesian fitting code, HerBIE, coupled with the THEMIS dust model. Our dust modeling is able to reproduce the near-IR to millimeter emission of NGC 891, with the exception of an excess at a level of 25% obtained by the NIKA2 observations in the outermost parts of the disk. The radio continuum and thermal dust emission are distributed differently in the disk and galaxy halo. Different dusty environments are also revealed by a multiwavelength investigation of the emission features. Our detailed decomposition at millimeter and centimeter wavelengths shows that emission at 1 mm is purely originated by dust. Radio components become progressively important with increasing wavelengths. Finally, we find that emission arising from small dust grains accounts for ~ 9.5% of the total dust mass, reaching up to 20% at large galactic latitudes. Shock waves in the outflows that shatter the dust grains might explain this higher fraction of small grains in the halo
IAS/CEA Evolution of Dust in Nearby Galaxies (ICED): the spatially-resolved dust properties of NGC4254
International audienceWe present the first preliminary results of the project \textit{ICED}, focusing on the face-on galaxy NGC4254. We use the millimetre maps observed with NIKA2 at IRAM-30m, as part of the IMEGIN Guaranteed Time Large Program, and of a wide collection of ancillary data (multi-wavelength photometry and gas phase spectral lines) that are publicly available. We derive the global and local properties of interstellar dust grains through infrared-to-radio spectral energy distribution fitting, using the hierarchical Bayesian code HerBIE, which includes the grain properties of the state-of-the-art dust model, THEMIS. Our method allows us to get the following dust parameters: dust mass, average interstellar radiation field, and fraction of small grains. Also, it is effective in retrieving the intrinsic correlations between dust parameters and interstellar medium properties. We find an evident anti-correlation between the interstellar radiation field and the fraction of small grains in the centre of NGC4254, meaning that, at strong radiation field intensities, very small amorphous carbon grains are efficiently destroyed by the ultra-violet photons coming from newly formed stars, through photo-desorption and sublimation. We observe a flattening of the anti-correlation at larger radial distances, which may be driven by the steep metallicity gradient measured in NGC4254