Search my publications on SPIRES, ADS, or astro-ph

Recent preprints:

  • Axions, Inflation and the Anthropic Principle (KJM)

    arXiv:0911.0421, submitted to Physical Review D

    Summary: (coming soon)


  • Cosmological Problems with Multiple Axion-like Fields (KJM & P.J. Steinhardt)

    arXiv:0911.0418, submitted to Physical Review D

    Summary: (coming soon)


  • Primordial black holes in the Dark Ages: Observational prospects for future 21cm surveys (KJM & D.H. Wesley)

    arXiv:0805.1531, submitted to Physical Review D

    Summary: If primordial black holes were evaporating during the cosmological Dark Ages when the universe was dominated by neutral hydrogen gas, the effects of the Hawking radiation on the neutral hydrogen may be detectable in future high-redshift 21cm radio interferometry surveys. We present the signal that would be seen in the 21cm fluctuation power spectrum and discuss the instrumental requirements and challenges for such an observation. We show that the high-redshift 21cm fluctuation power spectrum has the potential to place strong limits on evaporating primordial black holes and other exotic energy sources in the Dark Ages.

Published works:

  • Effect of primordial black holes on the cosmic microwave background and cosmological parameter estimation (M. Ricotti, J.P. Ostriker & KJM)

    The Astrophysical Journal, 680, 829 (2008)

    Summary: Massive, non-evaporating primordial black holes can ionize and heat the intergalactic medium in the epoch before the formation of stars and galaxies by accreting baryonic matter and producing X-rays. We show that failing to account for a non-standard recombination history can lead to a misestimation of cosmological parameters. We also discuss the effect of primordial black hole baryon accretion on the primordial molecular hydrogen abundance, which may affect the rate of formation of the first stars and galaxies.


  • Observing cosmic string loops with gravitational lensing surveys (KJM, D.H. Wesley & L.J. King)

    Phys. Rev. D 76, 123515

    Summary: Current constraints on the existence of cosmic strings mainly rely on an understanding of their emission of gravitational radiation. Taking a different approach, we start with an estimate of the gravitational lensing effect of a typical cosmic string loop against a background radio source and use this to predict the constraints that might be reached with extant and future radio surveys.


  • Growth of structure seeded by primordial black holes (KJM, J.P. Ostriker & M. Ricotti)

    The Astrophysical Journal, 665, 1277 (2007)

    Summary: We discuss the constraints on massive (non-evaporating) primordial black holes (PBHs) as a component of dark matter. We also explore the possibilities for PBHs to contribute to the early growth of supermassive black holes or to become the intermediate-mass black holes whose existence may account for ultraluminous x-ray sources seen today.


  • The Lyth bound revisited (G.P. Efstathiou & KJM)

    Journal of Cosmology and Astroparticle Physics, 05 (2005) 008

    Summary: The Lyth bound relates the tensor-scalar ratio to the variation in the inflaton field over the course of inflation. We study a population of inflationary models produced stochastically using the inflationary flow equations and with a minimal set of assumptions to test this relationship and comment on its implications for the future detection of a primordial tensor signal.


  • Foregrounds for 21-cm observations of neutral gas at high redshift (S.P. Oh & KJM)

    Monthly Notices of the Royal Astronomical Society, 346, 871 (2003)

    Summary: One of the biggest challenges for observing the cosmological Dark Ages with redshifted 21cm radio observations will be overcoming a wide range of foregrounds. We investigate the effects of foregrounds on spatial tomography of neutral gas at high redshift and on observations of spectral features along a pencil-beam slice.