Related papers: Two-photon production in low-velocity shocks
The physical origin of high velocity cool gas seen in galactic winds remains unknown. Following Wang (1995), we argue that radiative cooling in initially hot thermally-driven outflows can produce fast neutral atomic and photoionized cool…
We have obtained high resolution FUSE and HST/STIS echelle observations of the quasar PG 1116+215. The semi-continuous coverage of the ultraviolet spectrum over the wavelength range 916-2800 provides detections of Galactic and high velocity…
A population of early star-forming galaxies is the leading candidate for the re-ionization of the universe. It is still unclear what conditions and physical processes would enable a significant fraction of the ionizing photons to escape…
The most popular models for the complex phase and time lags in the rapid aperiodic variability of Galactic X-ray binaries are based Comptonization of soft seed photons in a hot corona, where small-scale flares are induced by flares of the…
We investigate models for the photoionization of the widespread diffuse ionized gas in galaxies. In particular we address the long standing question of the penetration of Lyman continuum photons from sources close to the galactic midplane…
We explore the origin of the observed Lya and other UV lines from galaxies at z<3.7 by detailed modelling of the spectra. The objects are chosen among those showing a) UV-optical-near-IR lines, b) only UV lines and c) those showing Lya in…
Interstellar ice mantles on the surfaces of dust grains are thought to have a bi-layered structure, with a H2O-rich polar layer, covered by a CO-rich apolar layer that probably harbors H2 and other volatiles such as N2. In this work, we…
The Magellanic Stream and several high velocity clouds have now been detected in optical line emission. The observed emission measures and kinematics are most plausibly explained by photoionization due to hot, young stars in the Galactic…
We present the properties of 17 faint Ly$\alpha$ emitting galaxies (LAEs) at $z>5.8$ from the JWST Advanced Deep Extragalactic Survey (JADES) in the Hubble Ultra Deep Field/GOODS-S. These LAEs span a redshift range $z\approx5.8-8.0$ and a…
We present integral field spectroscopy of a Lyman-alpha blob at redshift 2.38, with a spectral resolution three times better than previous published work. As with previous observations, the blob has a chaotic velocity structure, much of…
Context. There is a population of runaway stars that move at extremely high speeds with respect to their surroundings. The fast motion and the stellar wind of these stars, plus the wind-medium interaction, can lead to particle acceleration…
High resolution spectroscopy with FUSE and STIS of atomic and molecular velocity stratification in the nebular outflow of M27 challenge models for the abundance kinematics in planetary nebulae. The simple picture of a very high speed (~…
(ABRIDGED)The Ly$\alpha$ clouds at low redshifts (z < 1.7)observed by HST showed us two unexpected features: Lanzetta et.al.establised the association between Ly$\alpha$ clouds and galaxies, and Ulmer pointed out the strong clustering of…
The heating and cooling of the interstellar medium allow the gas in the ISM to coexist at very different temperatures in thermal pressure equilibrium. The heating cannot be directly determined, but the cooling can be inferred from…
Galactic winds are associated with intense star formation and AGNs. Depending on their formation mechanism and velocity they may remove a significant fraction of gas from their host galaxies, thus suppressing star formation, enriching the…
Observations of SN1006 have shown that ions and electrons in the plasma behind fast supernova remnant shock waves are far from equilibrium, with the electron temperature much lower than the proton temperature and ion temperatures…
Surveys for nearby low-luminosity dwarfs tend to avoid the crowded regions of the Galactic Plane. We have devised near-infrared colour-magnitude and colour-colour selection criteria designed to identify late-type M and early-type L dwarfs…
We report evidence for a bimodality in damped Ly systems (DLAs). Using [C II] 158 mu cooling rates, lc, we find a distribution with peaks at lc=10^-27.4 and 10^-26.6 ergs s^-1 H^-1 separated by a trough at lc^crit ~= lc < 10^-27.0 ergs s^-1…
A novel two-stage helium buffer gas cooled beam source is introduced. The properties of the molecular beams produced from this source are investigated theoretically using the CaF as a test molecule. The gas-phase molecules are first…
We study the formation of a partially ionized zone behind the usual H II zone in photo-ionized gas for gas density intermediate between ordinary H II regions and AGN BLRs and without X-rays. While Lyman continuum photons are depleted before…