Related papers: Radiative feedback from an early X-ray background
Feedback to the interstellar medium (ISM) from ionising radiation, stellar winds and supernovae is central to regulating star formation in galaxies. Due to their low mass ($M_{*} < 10^{9}$\,M$_\odot$), dwarf galaxies are particularly…
We study the inhomogeneous reionization in a critical density CDM universe due to stellar sources, including Population III objects. The spatial distribution of the sources is obtained from high resolution numerical N-body simulations. We…
Star formation from the interstellar medium of galactic disks is a basic process controlling the evolution of galaxies. Understanding the star formation rate in a local patch of a disk with a given gas mass is thus an important challenge…
We model Pop III star formation in different FUV and X-ray backgrounds, including radiation feedback from protostars. We confirm previous results that a moderate X-ray background increases the number of Pop III systems per unit cosmological…
Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the…
The ultraviolet (UV) light from a host star influences a planet's atmospheric photochemistry and will affect interpretations of exoplanetary spectra from future missions like the James Webb Space Telescope. These effects will be…
Accumulating evidence indicates that some of ultra-luminous X-ray sources (ULXs) are intermediate mass black holes (IMBHs), but the formation process of IMBHs is unknown. One possibility is that they were formed as remnants of population…
We present chemical models of the envelope of a young stellar object (YSO) exposed to a central X-ray source. The models are applied to the massive star-forming region AFGL 2591 for different X-ray fluxes. The total X-ray ionization rate is…
Molecular hydrogen allows cooling in primordial gas, facilitating its collapse into Population III stars within primordial halos. Lyman-Werner (LW) radiation from these stars can escape the halo and delay further star formation by…
We show that ultraviolet radiation, with wavelengths shorter than 2000 A, escaping from the disks of giant spirals could be one of the principal factors affecting the evolution of low mass satellite galaxies. We demonstrate, using a…
We present a set of controlled hydrodynamical simulations to study the effects of strong galactic outflows on the density and temperature structures, and associated X-ray signatures, of extra-planar and circumgalactic gas. We consider three…
Lyman-Werner (LW) radiation photodissociating molecular hydrogen (H$_2$) influences the thermal and dynamical evolution of the Population III (Pop III) star-forming gas cloud. The effect of powerful LW radiation has been well investigated…
Here we consider the strong evolution experienced by the matter reinserted by massive stars, both in giant star forming regions driven by a constant star formation rate, and in massive and coeval superstar clusters. In both cases we take…
The first billion years in the evolution of the Universe mark the formation of the first stars, black holes and galaxies. The radiation from the first galaxies plays an important role in determining the final state of primordial gas…
Exoplanet atmospheres are known to be vulnerable to mass loss through irradiation by stellar X-ray and extreme-ultraviolet emission. We investigate how this high-energy irradiation varies with time by combining an empirical relation…
The presence of supermassive black holes (SMBHs) of a few billion solar masses at very high redshift has motivated us to study how these massive objects formed during the first billion years after the Big Bang. The most promising model that…
We perform a large set of cosmological simulations of early structure formation and follow the formation and evolution of 1540 star-forming gas clouds to derive the mass distribution of primordial stars. The star formation in our…
We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar energy distributions (SEDs) and initial mass…
Even today in our Galaxy, stars form from gas cores in a variety of environments, which may affect the properties of resulting star and planetary systems. Here we study the role of pressure, parameterized via ambient clump mass surface…
The spectral energy distribution, variability and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum.…