Dr Roland Crocker

Adjunct Research Fellow PhD, Particle astrophysics, University of Melbourne, 2003 B.A./B.Sc. (Hons), University of Melbourne, 1999 Phone +61 (3) 9905 3636 FAX +61 (3) 9905 3637 Email:Roland.Crocker@monash.edu

The ~1012 eV diffuse gamma-ray glow along the Galactic plane revealed by the HESS instrument. Figure credit: HESS Collaboration. The dark star shows the position of the super-massive black hole located at the very centre of the Milky Way. The longitudinal extent of the image is approximately 1800 lightyears. The earth is located around 26 000 lightyears from the Galactic centre.

Explanation: the nucleus of the Milky Way presents a superb laboratory of modern astrophysics where astronomers and astrophysicists can study at unprecedented spatial resolution and across the entire electromagnetic spectrum physical processes that may also happen in the cores of other galaxies. In common with most other galaxies, right at the centre of our Galaxy lurks an enormous black hole (ours has a mass around four million times that of the sun). Processes occurring close to this object may ultimately be responsible for powering many of the high-energy phenomena seen in the Galactic centre region. For instance, observations conducted by the HESS instrument in Namibia have recently revealed that the molecular gas pervading the central few hundred lightyears around our Galactic centre glows brightly in high-energy gamma rays. With my collaborators I am investigating the idea that these gamma rays are created in collisions between a population of high-energy cosmic rays (accelerated relatively close to the event horizon of the super-massive black hole) and ambient gas.

RESEARCH INTERESTS

• high-energy phenomenology of the Galactic centre
• the Galactic centre magnetic field
• cosmic rays and neutrinos from Galactic and extragalactic sources
• implications of cosmic rays for Galactic dynamics and cosmology.

Teaching

• third year Statistical Mechanics (PHS3031 sub-unit 2, semester 1)
• third year Elementary Particles (PHS3062 sub-unit 2, semester 2).

SELECTED PUBLICATIONS

1. *Crocker, R. M.; Jones, D.; Protheroe, R. J.; Ott, J.; Ekers, R.; Melia, F.; Stanev, T.; Green, A. (2007), The Cosmic Ray Distribution in Sagittarius B, The Astrophysical Journal, Volume 666, Issue 2, pp. 934-948. [5]
2. James, C. W.; Crocker, R. M.; Ekers, R. D.; Hankins, T. H.; O'Sullivan, J. D.; Protheroe, R. J. (2007), Limit on ultrahigh energy neutrino flux from the Parkes Lunar Radio Cherenkov experiment, Monthly Notices Royal Astronomical Society Volume 379, Issue 3, pp. 1037-1041. [2]
3. *Crocker, R. M.; Jones, D.; Ballantyne, D. R.; Melia, F. (2007), Radio Synchrotron Emission from Secondary Leptons in the Vicinity of Sagittarius A*, Astrophysical Journal Letters Volume 664, Issue 2, pp. L95-L98. [0]
4. *Ballantyne, D. R.; Melia, F.; Liu, S.; Crocker, R. M. (2007), A Possible Link Between the Galactic Center HESS Source and Sgr A*, Astrophysical Journal Letters Volume 657, Issue 1, pp. L13-L16. [2]
5. *Crocker, R. M.; Fatuzzo, M.; Jokipii, J. R.; Melia, F.; Volkas, R. R. (2005), The AGASA and SUGAR Anisotropies and TeV Gamma Rays from the Galactic Center: A Possible Signature of Extremely High Energy Neutrons, The Astrophysical Journal, Volume 622, Issue 2, pp. 892-909. [37]
6. *Crocker, R. M.; Melia, F.; Volkas, R. R. (2005), Neutrinos from the Galactic Center in the Light of Its Gamma-Ray Detection at TeV Energy, The Astrophysical Journal Letters, Volume 622, Issue 1, pp. L37-L40. [10]
7. Crocker, R. M.; Giunti, C. ; Mortlock, D. J. (2004), Neutrino interferometry in curved spacetime, Physical Review D, vol. 69, Issue 6, id. 063008. [3]

Refereed conference papers

8. Crocker, R. M. (2006), Neutrons (and Neutrinos) from the Galactic Center, Journal of Physics: Conference Series, Volume 47, Issue 1, pp. 205-212. [0]
9. Peele, A. G.; Lyngsjo, H.; Crocker, R. M.; Markham, J.; Bannister, N.; Nugent, K.A. (2004), Modeling of the Lobster-ISS x-ray telescope in orbit, UV and Gamma-Ray Space Telescope Systems. Edited by Hasinger, Gnther; Turner, Martin J. L. Proceedings of the SPIE, Volume 5488, pp. 232-241. [0]

Other publications

10. Clay, R. & Crocker, R. M. (2007), Exploring the High-Energy Cosmic Ray Spectrum with a Toy Model of Cosmic Ray Diffusion, Submitted to Astroparticle Physics (eprint arXiv:0710.4990) [0]
11. *Fatuzzo, M.; Melia, F.; Crocker, R. M. (2006), High-Energy Activity in the Unusually Soft TeV Source HESS J1804-216 Toward the Galactic Center, (eprint arXiv, astro-ph/ 0602330). [5]