Cosmological Problems with Multiple Axion-like Fields (2009)
Mack, Katherine J., Steinhardt, Paul J.
Incorporating the QCD axion and simultaneously satisfying current constraints on the dark matter density and isocurvature fluctuations requires non-minimal fine-tuning of inflationary parameters or...
Axions, Inflation and the Anthropic Principle (2009)
The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation,...
Primordial black holes in the Dark Ages: Observational prospects for future 21cm surveys (2008)
Mack, Katherine J., Wesley, Daniel H.
We consider the signatures of a population of primordial black holes (PBHs) in future observations of 21cm radiation from neutral hydrogen at high redshift. We focus on PBHs in the mass range $5...
Ricotti, Massimo, Ostriker, Jeremiah P., Mack, Katherine J.
We investigate the effect of non-evaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic...
Observing cosmic string loops with gravitational lensing surveys (2007)
Mack, Katherine J., Wesley, Daniel H., King, Lindsay J.
We show that the existence of cosmic strings can be strongly constrained by the next generation of gravitational lensing surveys at radio frequencies. We focus on cosmic string loops, which...
Growth of structure seeded by primordial black holes (2006)
Mack, Katherine J., Ostriker, Jeremiah P., Ricotti, Massimo
We discuss the possibilities for primordial black holes (PBHs) to grow via the accretion of dark matter. In agreement with previous works, we find that accretion during the radiation-dominated era...
The Lyth Bound Revisited (2005)
Efstathiou, George, Mack, Katherine J.
We investigate the Lyth relationship between the tensor-scalar ratio, r, and the variation of the inflaton field, Delta phi, over the course of inflation. For inflationary models that produce at...
Foregrounds for 21cm Observations of Neutral Gas at High Redshift (2003)
Oh, S. Peng, Mack, Katherine J.
We investigate a number of potential foregrounds for an ambitious goal of future radio telescopes such as the Square Kilometer Array (SKA) and Low Frequency Array (LOFAR): spatial tomography of...