Star Formation Indicators and Line Equivalent Width in Lyman Alpha Galaxies (2009)
Dijkstra, Mark, Westra, Eduard
The equivalent width (EW) of the Lyman Alpha (Lya) line is directly related to the ratio of star formation rates determined from Lya flux and UV flux density [SFR(Lya)/SFR(UV)]. We use published data...
Active Galactic Nuclei (AGN) produce a dominant fraction (~80%) of the Soft X-ray background (SXB) at photon energies 0.5
Explaining the Observed Lyman Alpha `Blobs' as Cold Streams of Gas in the Halos of Galaxies (2009)
Over the past decade, mysterious blobs of Lyman alpha (Lya) emission by hydrogen have been discovered in the vicinity of galaxies at early cosmic times. Although a number of possible models were...
Dijkstra, Mark, Haiman, Zoltan, Mesinger, Andrei, Wyithe, Stuart
The earliest generation of stars and black holes must have established an early 'Lyman-Werner' background (LWB) at high redshift, prior to the epoch of reionization. Because of the long mean free...
On the Detectability of the Hydrogen 3-cm Fine Structure Line from the EoR (2008)
Dijkstra, Mark, Lidz, Adam, Pritchard, Jonathan R., Greenhill, Lincoln J., Mitchell, D. A., Ord, S. M., ...
A soft ultraviolet radiation field, 10.2 eV < E 2p_3/2) against the Cosmic Microwave Background out to very high redshifts. In particular, the optical depth in the fine-structure line through...
Acceleration of Galactic Supershells by Lyman Alpha Radiation (2008)
Scattering of Lyman Alpha (hereafter Lya) photons by neutral hydrogen gas in a single outflowing 'supershell' around star forming regions often explains the shape and offset of the observed Lya...
Lyman Alpha Driven Outflows Around Star Forming Galaxies (2008)
We present accurate Monte-Carlo calculations of Lyman Alpha (hereafter Lya) radiation pressure in a range of models which represent galaxies during various epochs of our Universe. We show that the...
UV Radiative Feedback During the Advanced Stages of Reionization (2008)
Mesinger, Andrei, Dijkstra, Mark
The ionizing ultraviolet background (UVB) during reionization can suppress the gas content of low-mass galaxies, even those capable of efficient atomic cooling, and thus lead to an extended...
Continuum Emission by Cooling Clouds (2007)
The collapse of baryons into the center of a host dark matter halo is accompanied by radiation that may be detectable as compact (< 10 kpc) UV-continuum and Lyman Alpha (hereafter Lya) emission with...
The Polarization of Scattered Lyman Alpha Radiation Around High-Redshift Galaxies (2007)
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...
Very Massive Stars in High-Redshift Galaxies (2007)
Dijkstra, Mark, Wyithe, Stuart
A significant fraction of Lyman Alpha (Lya) emitting galaxies (LAEs) at z> 5.7 have rest-frame equivalent widths (EW) greater than ~100 Angstrom. However only a small fraction of the Lya flux...
The Impact of The IGM on High-Redshift Lyman Alpha Emission Lines (2007)
Dijkstra, Mark, Lidz, Adam, Wyithe, Stuart
We calculate the impact of the intergalactic medium (IGM) on the observed Lyman alpha lines (hereafter Lya) emitted by galaxies in an ionised IGM at z>4. Our model accounts for gas clumping in the...
Luminosity Functions of Lyman Alpha Emitting Galaxies and Cosmic Reionization of Hydrogen (2006)
Dijkstra, Mark, Wyithe, Stuart, Haiman, Zoltan
Recent observations imply that the observed number counts of Lya Emitters (LAEs) evolved significantly between z=5.7 and z=6.5. It has been suggested that this was due to a rapid evolution in the...
Requirements for Cosmological 21-cm Masers (2006)
We perform Monte-Carlo calculations of the radiative transfer of Lyman Alpha (hereafter Lya) photons emitted by a source embedded in a neutral collapsing gas cloud. This represents a young galaxy or...
Lyman Alpha Constraints on Very Low Luminosity AGN (2006)
Dijkstra, Mark, Wyithe, Stuart
Recent surveys have detected Lya emission from z=4.5-6.5 at luminosities as low as 10^41 erg/s. There is good evidence that low numbers of AGN are among observed faint Lya emitters. Combining these...
Dijkstra, Mark, Haiman, Zoltan, Spaans, Marco
We present Monte Carlo calculations of Lyman alpha (Lya) radiative transfer through collapsing gas clouds, representing proto-galaxies that are caught in the process of their assembly. Such galaxies...
Lyman Alpha Radiation From Collapsing Protogalaxies II: Observational Evidence for Gas Infall (2005)
Dijkstra, Mark, Haiman, Zoltan, Spaans, Marco
We model the spectra and surface brightness distributions for the Lyman alpha (Lya) radiation expected from protogalaxies that are caught in the early stages of their assembly. We use the results of...
Constraints on high redshift galaxy formation and its impact on the intergalactic medium (2005)
The formation and evolution of galaxies and the thermodynamic state of the inter-galactic medium (IGM) are fundamentally intertwined. The formation of stars is associated with various mechanisms that...
Constraints on high redshift galaxy formation and its impact on the intergalactic medium (2005)
Department: Astronomy.
On Detecting the X-ray Silhouette of a Damped Lyman alpha System (2004)
Dijkstra, Mark, Haiman, Zoltan, Scharf, Caleb
We explore the possibility of resolving an image of a damped Lyman alpha (DLA) system in absorption against an extended, diffuse background X-ray source. Typical columns of neutral hydrogen in DLAs...
The Growth of the Earliest Supermassive Black Holes and Their Contribution to Reionization (2004)
Haiman, Zoltan, Dijkstra, Mark, Mesinger, Andrei
We discuss currently available observational constraints on the reionization history of the intergalactic medium (IGM), and the extent to which accreting black holes (BHs) can help explain these...
A Limit from the X-ray Background on the Contribution of Quasars to Reionization (2004)
Dijkstra, Mark, Haiman, Zoltan, Loeb, Abraham
A population of black holes (BHs) at high redshifts (z>6) that contributes significantly to the ionization of the intergalactic medium (IGM) would be accompanied by the copious production of hard...
Photoionization Feedback in Low--Mass Galaxies at High Redshift (2003)
Dijkstra, Mark, Haiman, Zoltan, Rees, Martin J., Weinberg, David H.
The cosmic ultraviolet (UV) ionizing background impacts the formation of dwarf galaxies in the low-redshift universe (z=3) by suppressing gas infall into galactic halos with circular velocities up to...
Beyond Lyman-alpha: Constraints and Consistency Tests from the Lyman-beta Forest (2003)
Dijkstra, Mark, Lidz, Adam, Hui, Lam
Absorption between the rest-frame wavelengths of 973 and 1026 Angstroms in quasar spectra arises from two sources (apart from occasional metals): one is due to Lyman-alpha (Lya) absorption by...