相关论文: Polarization of the \lya Halos Around Sources Befo…
The spectra of the first galaxies and quasars in the Universe should be strongly absorbed shortward of their rest-frame Lyman-alpha wavelength by neutral hydrogen (HI) in the intervening intergalactic medium. However, the Lyman-alpha line…
The high-redshift Universe contains luminous Lyman Alpha (hereafter Lya) emitting sources such as galaxies and quasars. The emitted Lya radiation is often scattered by surrounding neutral hydrogen atoms. We show that the scattered Lya…
We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing sources. For various sets of simulated 21-cm…
The history of the transition from a neutral intergalactic medium (IGM) to one that is almost fully ionized can reveal the character of cosmological ionizing sources. We study the evolution of the volume filling factor of HII and HeIII…
When modelling the ionisation of gas in the intergalactic medium after reionisation, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that…
We observed 51 sources in the Q-U-I JOint TEnerife (QUIJOTE) cosmological fields which were brighter than 1 Jy at 30 GHz in the Planck Point Source Catalogue (version 1), with the Very Large Array at 28 -- 40 GHz, in order to characterise…
I use cosmological simulations that incorporate a physically motivated approximation to three-dimensional radiative transfer that recovers correct asymptotic ionization front propagation speeds for some cosmologically relevant density…
In this paper, we present the formalism of simulating Lyman-$\alpha$ emission and polarization around reionization ($z$ = 8) from a plane-parallel ionization front. We accomplish this by using a Monte Carlo method to simulate the production…
We present deep VLA observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.6" and 10". At 1.6", we find that the peak flux cumulative number count distribution is N($>$p) $\sim$ 45 *…
The fraction of galaxies with strong Ly$\alpha$ emission has been observed to decrease rapidly with redshift at $z \ge 6$, after a gradual increase at $z< 6$. This has been interpreted as a hint of the reionization of the intergalactic…
The first sources of ionizing radiation to condense out of the dark and neutral IGM sent ionization fronts sweeping outward through their surroundings, overtaking other condensed objects and photoevaporating them. This feedback effect of…
We present a formalism that incorporates hydrogen Lyman-alpha (Ly$\alpha$) polarization arising from the scattering of radiation in galaxy halos into the intensity mapping approach. Using the halo model, and emission profiles based on…
While cosmic reionization has been broadly constrained by global observables, the interplay between internal sources (Milky Way, M31, and their satellites) and external ionization fronts remains poorly understood in a realistic Local Group…
We quantify the contribution of Ly$\alpha$ fluorescence to observed spatially extended Ly$\alpha$ halos around Ly$\alpha$ emitters (LAE) at redshift ${\rm z=3.1}$. The key physical quantities that describe the fluorescent signal include…
We have investigated the linear polarisation of Lya transferred in a static, dustless, and thick plane-parallel slab that is uniformly filled with neutral hydrogen. Because the scattering phase function is characterised by the dipole type…
To understand the mechanism behind high-$z$ Ly${\alpha}$ nebulae, we simulate the scattering of Ly${\alpha}$ in a $\rm H\,I$ halo about a central Ly${\alpha}$ source. For the first time, we consider both smooth and clumpy distributions of…
The unification scheme of active galactic nuclei (AGNs) invokes an optically thick molecular torus component hiding the broad emission line region. Assuming the presence of a thick neutral component in the molecular torus characterized by a…
We have used polarimetric imaging to study the magneto-ionic medium of the Galaxy, obtaining 1420 MHz images with an angular resolution of 1' over more than 40 square-degrees of sky around the W3/W4/W5/HB3 HII region/SNR complex in the…
Two methods are developed for solving the steady-state spherically symmetric radiative transfer equation for resonance line radiation emitted by a point source in the Intergalactic Medium. One method is based on solving the ray and moment…
We estimate the effects of weak lensing by large-scale density inhomogeneities and long-wavelength gravitational waves upon the polarization properties of electromagnetic radiation as it propagates from cosmologically distant sources.…