Now showing items 1-20 of 67

• #### 3-Cm Fine Structure Masers: A Unique Signature of Supermassive Black Hole Formation via Direct Collapse in the Early Universe ﻿

(American Astronomical Society, 2016)
The direct collapse black hole (DCBH) scenario describes the isothermal collapse of a pristine gas cloud directly into a massive, M_BH=10^4-10^6 M_sun black hole. In this paper we show that large HI column densities of ...
• #### Absence of a Thick Atmosphere on the Terrestrial Exoplanet LHS 3844b ﻿

(Springer Science and Business Media LLC, 2019-08-19)
The majority of terrestrial planets in the Galaxy orbit small stars with radii less than 60% that of the Sun1,2. Theoretical models predict that these planets are more vulnerable to at- mospheric escape and collapse than ...
• #### Astrophysical Russian dolls ﻿

(Springer Nature, 2017)
Are there examples of "astrophysical Russian dolls," and what could we learn from their similarities? In this article, we list a few such examples, including disks, filaments, and clusters. We suggest that forging connections ...
• #### Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451 ﻿

(Springer Nature, 2011)
Active galactic nuclei, which are powered by long-term accretion onto central supermassive black holes, produce1 relativistic jets with lifetimes of at least one million years, and the observation of the birth of such a ...
• #### Blackbody Radiation From Isolated Neptunes ﻿

(American Astronomical Society, 2016)
Recent analyses of the orbits of some Kuiper Belt objects hypothesize the presence of an undiscovered Neptune-size planet at a very large separation from the Sun. The energy budget of Neptunes on such distant orbits is ...
• #### CEMP stars: possible hosts to carbon planets in the early Universe ﻿

(Oxford University Press (OUP), 2016)
We explore the possibility of planet formation in the carbon-rich protoplanetary disks of carbon-enhanced metal-poor (CEMP) stars, possible relics of the early Universe. The chemically anomalous abundance patterns ([C/Fe] ...
• #### CHIPS: The Cosmological HI Power Spectrum Estimator ﻿

(American Astronomical Society, 2016)
Detection of the cosmological neutral hydrogen signal from the Epoch of Reionization, and estimation of its basic physical parameters, is the principal scientific aim of many current low-frequency radio telescopes. Here ...
• #### Constraining the CMB optical depth through the dispersion measure of cosmological radio transients ﻿

(IOP Publishing, 2016)
The dispersion measure of extragalactic radio transients, such as of recently discovered Fast Radio Burst FRB150418, can be used to measure the column density of free electrons in the intergalactic medium. The same electrons ...
• #### Constraining the Milky Way mass with hypervelocity stars ﻿

(Elsevier BV, 2017)
Context. Although a variety of techniques have been employed for determining the Milky Way dark matter halo mass distribution, the range of allowed masses spans both light and heavy values. Knowing the precise mass of our ...
• #### Contribution of quasar-driven outflows to the extragalactic gamma-ray background ﻿

(Springer Science and Business Media LLC, 2016-07-25)
The origin of the extragalactic γ-ray background permeating throughout the Universe remains a mystery forty years after its discovery. The extrapolated population of blazars can account for only half of the background ...
• #### Cosmological Recombination of Lithium and Its Effect on the Microwave Background Anisotropies ﻿

(IOP Publishing, 2002)
The cosmological recombination history of lithium, produced during big bang nucleosynthesis, is presented using updated chemistry and cosmological parameters consistent with recent cosmic microwave background (CMB) ...
• #### Cumulative neutrino background from quasar-driven outflows ﻿

(IOP Publishing, 2016-12-06)
Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar ...
• #### Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization ﻿

(American Astronomical Society, 2016)
The Detection of redshifted 21 cm emission from the epoch of reionization (EoR) is a challenging task owing to strong foregrounds that dominate the signal. In this paper, we propose a general method, based on the delay ...
• #### Density Jumps Near the Virial Radius of Galaxy Clusters ﻿

(American Astronomical Society, 2016)
Recent simulations have indicated that the dark matter halos of galaxy clusters should feature steep density jumps near the virial radius. Since the member galaxies are expected to follow similar collisionless dynamics as ...
• #### Detectability of Local Group Dwarf Galaxy Analogues at High Redshifts ﻿

(IOP Publishing, 2015)
The dwarf galaxies of the Local Group are believed to be similar to the most abundant galaxies during the epoch of reionization (z>6). As a result of their proximity, there is a wealth of information that can be obtained ...
• #### Detecting stars at the galactic centre via synchrotron emission ﻿

(Oxford University Press (OUP), 2015)
Stars orbiting within 1$\arcsec$ of the supermassive black hole in the Galactic Centre, Sgr A*, are notoriously difficult to detect due to obscuration by gas and dust. We show that some stars orbiting this region may be ...
• #### Detecting Triple Systems With Gravitational Wave Observations ﻿

(American Astronomical Society, 2017)
The Laser Interferometer Gravitational Wave Observatory (LIGO) has recently discovered gravitational waves (GWs) emitted by merging black hole binaries. We examine whether future GW detections may identify triple companions ...
• #### Detection of Gravitational Wave Emission by Supermassive Black Hole Binaries Through Tidal Disruption Flares ﻿

(Nature Publishing Group, 2016)
Galaxy mergers produce supermassive black hole binaries, which emit gravitational waves prior to their coalescence. We perform three-dimensional hydrodynamic simulations to study the tidal disruption of stars by such a ...
• #### The Distortion of the Cosmic Microwave Background Spectrum Due to Intergalactic Dust ﻿

(American Astronomical Society, 2016)
Infrared emission from intergalactic dust might compromise the ability of future experiments to detect subtle spectral distortions in the Cosmic Microwave Background (CMB) from the early Universe. We provide the first ...
• #### The Dynamics and Evolution of Supermassive Black Holes in Merging Galaxies ﻿

(2012-08-03)
This thesis is a theoretical study of supermassive black holes (SMBHs) in merging galaxies. We consider the dynamics that govern inspiralling SMBH pairs and gravitational-wave (GW) recoiling SMBHs, as well as the fueling ...