Related papers: Laboratory Photoionization Fronts in Nitrogen Gas:…
Recent studies showed that observations of line emission from shocks in YSO jets require a substantial amount of ionization of the pre-shock matter. Photoionization from X-ray emitted close to the central source may be responsible for the…
A 2D approach is used to simulate the properties of positive and negative streamers emerging from a high-voltage electrode in a long (14 cm) air gap for standard pressure and temperature. The applied voltage varies from 100 to 500 kV. To…
We construct atmosphere models for strongly magnetized neutron stars with surface fields $B\sim 10^{12}-10^{15}$ G and effective temperatures $T_{\rm eff}\sim 10^6-10^7$ K. The atmospheres directly determine the characteristics of thermal…
A photoionized gas in thermal equilibrium can display a thermal instability, with 3 or more solutions in the multi-branch region of the S-shape curve giving the temperature versus the radiation-to-gas-pressure ratio. Many studies have been…
The organic compounds HCN and C2H2, present in protoplanetary disks, may react to form precursor molecules of the nucleobases, such as the pyrimidine molecule, C4H4N2. Depending on the temperature in a given region of the disk, molecules…
The strong electromagnetic fields carried by relativistic highly charged ions make heavy-ion colliders attractive places to study photonuclear interactions and two-photon interactions. At RHIC, three experiments have studied coherent…
Simulations are presented of the photoionisation of three dense gas clouds threaded by magnetic fields, showing the dynamical effects of different initial magnetic field orientations and strengths. For moderate magnetic field strengths the…
Here we report new ${\it ab initio}$ calculations of the effective recombination coefficients for the \ion{N}{ii} recombination spectrum. We have taken into account the density dependence of the coefficients arising from the relative…
An ionization front (I-front) that propagates through an inhomogeneous medium is slowed down by self-shielding and recombinations. We perform cosmological radiation hydrodynamics simulations of the I-front propagation during the epoch of…
We analyze the reliability of oxygen abundances and ionization parameters obtained from different diagnostic diagrams. For this, we compiled from the literature observational emission line intensities and oxygen abundance of 446…
The photoionization-driven evaporation of planetary atmospheres has emerged as a potentially fundamental process for planets on short period orbits. While 1-D studies have proven the effectiveness of stellar fluxes at altering the…
Compact, low-mass galaxies with strong nebular emission are considered promising candidates for efficient ionizing photon production and escape. We present a spatially resolved analysis of 189 galaxies at redshifts $z \sim 6.7-7.6$ in JADES…
We use photoionization models designed to reconcile the joint rest-UV-optical spectra of high-z star-forming galaxies to self-consistently infer the gas chemistry and nebular ionization and excitation conditions for ~150 galaxies from the…
The possibility that star-forming galaxies may leak ionizing photons is at the heart of many present-day studies that investigate the reionization of the Universe. We test this hypothesis on local blue compact dwarf galaxies of very high…
The photon-ion merged-beams technique for the photoionization of mass/charge selected ionized atoms, molecules and clusters by x-rays from synchrotron radiation sources is introduced. Examples for photoionization of atomic ions are…
We study the ionization structure of galactic outflows in 37 nearby, star forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to…
Photocatalytic nitrogen fixation provides a promising route to produce reactive nitrogen compounds at benign conditions. Titania has been reported as an active photocatalyst for reduction of dinitrogen to ammonia; however there is little…
Small, illuminated aerosol particles embedded in a gas experience a photophoretic force. Most approximations assume the mean particle surface temperature to be effectively the gas temperature. This might not always be the case. If the…
We use the recent detection of He II absorption at $z=2.2-2.6$ in the line of sight of the quasar HS1700+64 to put bounds on the sources of ionization. We find that given the uncertainty in $\tauhgp$ and the model of absorption in the…
We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the…