8 research outputs found
Diagnostics for mechanical heating in star-forming galaxies
In this thesis the molecular emission of
species such as CO, HCN and HNC and HCO+ are used to probe and quantify
mechanical heating in star-forming galaxies. In the first part of the
thesis photo-dissociation models are used to find a diagnostic of
mechanical heating at the level of molecular clouds. It was shown that
mechanical heating leaves a strong signature in diagnostics that involve
high-J to low-J transitions. In the second part of the thesis ,
synthetic line emission maps of molecular species are computed for model
star-forming galaxies. The emission from these maps are used as input
to photo-dissociation models in-order to constrain the physical
properties, such as gas density and visual extinction, of star-forming
galaxies. It was demonstrated that it is essential to consider
mechanical heating in modelling the emission of star-forming galaxies
using photo-dominated models.GalaxiesInterstellar matter and star formatio
Non-thermal photons and direct photodissociation of H, HD and HeH in the chemistry of the primordial Universe
International audienceNon-thermal photons deriving from radiative transitions among the internal ladder of atoms and molecules are an important source of photons in addition to thermal and stellar sources in many astrophysical environments. In the present work, the calculation of reaction rates for the direct photodissociation of some molecules relevant in early Universe chemistry is presented; in particular, the calculations include non-thermal photons deriving from the recombination of primordial hydrogen and helium atoms for the cases of H_2, HD and HeH^+. New effects on the fractional abundances of chemical species are investigated and the fits for the HeH^+ photodissociation rates by thermal photons are provided
Photodissociation with mechanical heating
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Diagnostics of the molecular component of PDRs with mechanical heating. II: Line intensities and ratios.' (bibcode: 2015A&A...574A.127K
Photodissociation with mechanical heating
VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Diagnostics of the molecular component of PDRs with mechanical heating. II: Line intensities and ratios.' (bibcode: 2015A&A...574A.127K
Euclid. IV. The NISP Calibration Unit
The near-infrared calibration unit (NI-CU) onboard Euclid's Near-Infrared Spectrometer and Photometer (NISP) is the first astronomical calibration lamp based on light-emitting diodes (LEDs) to be operated in space. Euclid is a mission in ESA's 'Cosmic Vision 2015-2025' framework, to explore the dark universe and provide a next-level characterisation of the nature of gravitation, dark matter, and dark energy. Calibrating photometric and spectrometric measurements of galaxies to better than 1.5% accuracy in a survey homogeneously mapping ~14000 deg^2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties, as well their constant monitoring in flight. To cover two of the main contributions - relative pixel-to-pixel sensitivity and non-linearity characteristics - as well as support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (=100 from ~15 ph s^-1 pixel^-1 to >1500 ph s^-1 pixel^-1. For this functionality, NI-CU is based on LEDs. We describe the rationale behind the decision and design process, describe the challenges in sourcing the right LEDs, as well as the qualification process and lessons learned. We also provide a description of the completed NI-CU, its capabilities and performance as well as its limits. NI-CU has been integrated into NISP and the Euclid satellite, and since Euclid's launch in July 2023 has started supporting survey operations
Euclid. IV. The NISP Calibration Unit
International audienceThe near-infrared calibration unit (NI-CU) onboard Euclid's Near-Infrared Spectrometer and Photometer (NISP) is the first astronomical calibration lamp based on light-emitting diodes (LEDs) to be operated in space. Euclid is a mission in ESA's 'Cosmic Vision 2015-2025' framework, to explore the dark universe and provide a next-level characterisation of the nature of gravitation, dark matter, and dark energy. Calibrating photometric and spectrometric measurements of galaxies to better than 1.5% accuracy in a survey homogeneously mapping ~14000 deg^2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties, as well their constant monitoring in flight. To cover two of the main contributions - relative pixel-to-pixel sensitivity and non-linearity characteristics - as well as support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (=100 from ~15 ph s^-1 pixel^-1 to >1500 ph s^-1 pixel^-1. For this functionality, NI-CU is based on LEDs. We describe the rationale behind the decision and design process, describe the challenges in sourcing the right LEDs, as well as the qualification process and lessons learned. We also provide a description of the completed NI-CU, its capabilities and performance as well as its limits. NI-CU has been integrated into NISP and the Euclid satellite, and since Euclid's launch in July 2023 has started supporting survey operations
Euclid. I. Overview of the Euclid mission
The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance
Euclid. I. Overview of the Euclid mission
International audienceThe current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance