I study millisecond pulsars. Millisecond pulsars are dead stars with about the mass of our sun, collapsed down to about the size of Lancaster, PA (10km across), and spinning about as fast as your kitchen blender. The fastest pulsar known, PSR J1748-2446ad, spins on its axis 716 times each second.
Pulsars are very accurate clocks, meaning they are predictable at the same level that atomic clocks are predictable. I use this feature of pulsars extensively. In particular, you can think of pulsars as a collection of clocks distributed throughout the galaxy. Anything that could disturb time, such as a perturbation in space-time, will effect the clocks. Pulsars are so predictable that we may be able to detect such a disturbance by observing pulsars.
Where would a space-time perturbation come from? It turns out that we think the the Universe is filled with gravitational radiation (a traveling space-time disturbance) but no one has measured it yet. This radiation is created, for example, anytime two black holes orbit around each other, and finally coalesce into a massive black hole.
Much of my research is concerned with increasing the sensitivity of the Pulsar Timing Array, which is a collection of millisecond pulsars that are precise enough clocks that we may use them to detect gravitational radiation soon.
For more articles and information on this project please see the following:
NANOGrav.org The home page of the North American NanoHertz Observatory of Gravitational Waves, of which I was the founding chair, and am now the International Liaison charged with creating the International Pulsar Timing Array under the auspices of a recent $6.5M NSF Partnerships in International Research and Education (PIRE) Grant.
In 2008 I started the Mid-Atlantic Relativistic Initiative in Education (MARIE) program which includes both an outreach program at McCaskey High in Lancaster, and an annual workshop in which undergraduate students present their research and outreach programs can exchange ideas. See here for some nice press we recently received in the local paper.
2010 September: F&M's article on the NSF PIRE Grant.
2008 March: F&M's article on my NSF CAREER Grant.
2002 January: Press Release on Pulsar Timing Array, UC Berkeley.
USA Today, 2002 January
At right you see Michael Johnson. a UCSB graduate student who worked with my group, Isaac Walstein '08, me, and Brian Burt '10 at the Arecibo Telescope in Puerto Rico while attending the first International Pulsar Timing Array meeting (see the NANOGrav site for more information.) Please visit my student project page for more information on my students and where they are now.
(Student co-authors are in shown as links. Clicking on the name will take you to a description of their work on my Student Project Page.)
"Pulsar Timing Arrays: No Longer a Blunt Instrument for Gravitational Wave Detection," Andrea N. Lommen (2011) submitted to JPCS, Proceedings of the 9th Edoardo Amaldi Conference on Gravitational Waves, and the 2011 Numerical Relativity - Data Analysis (NRDA) meeting, held 10-15 July 2011 in Cardiff, Wales, UK, July 10-15 2011. Arxiv: 1112.2158.
"A Bayesian parameter estimation approach to pulsar time-of-arrival analysis," Messenger, C.; Lommen, A.; Demorest, P.; and Ransom, S. (2011) Class. Quantum Grav. 28, 055001.
“Measuring the Mass of the Solar System Planets Using Pulsar Timing,” Champion, D. J.; and 21 co-authors. ApJ 720L: 201.
"Detection, Localization, and Characterization of Gravitational Wave Bursts in a Pulsar Timing Array," Finn, L. S. and Lommen, A. N. (2010) ApJ 718: 1400.
"Gravitational-wave detection via radio-pulsar timing," Demorest, P, Lazio, J, and Lommen, A, (2010) Physics Today, Volume 63, Issue 1, Quick Study. (You need a subscription to get this on the web, but I have a re-print I can send you. Just let me know.)
"Status update of the Parkes pulsar timing array," Verbiest, J and 19 co-authors (2010), Classical and Quantum Gravity, Volume 27, Issue 8, pp. 084015.
"The international pulsar timing array project: using pulsars as a gravitational wave detector," Hobbs, G and 57 co-authors, (2010) Classical and Quantum Gravity, Volume 27, Issue 8, pp. 084013.
"The North American Nanohertz Observatory for Gravitational Waves" Jenet, F.; Finn, L. S.; Lazio, J.; Lommen, A.; McLaughlin, M.; Stairs, I.; Stinebring, D.; Verbiest, J.; Archibald, A.; Arzoumanian, Z.; Backer, D.; Cordes, J.; Demorest, P.; Ferdman, R.; Freire, P.; Gonzalez, M.; Kaspi, V.; Kondratiev, V.; Lorimer, D.; Lynch, R.; Nice, D.; Ransom, S.; Shannon, R.; Siemens, X. (2009) NANOGrav consortium's submission to Astro2010's Program Prioritization Panel on Particle Astrophysics and Gravitation.
"TEMPO2: a new pulsar timing package - III. Gravitational wave simulation" Hobbs, G.; Jenet, F.; Lee, K. J.; Verbiest, J. P. W.; Yardley, D.; Manchester, R.; Lommen, A.; Coles, W.; Edwards, R.; Shettigara, C. (2009) MNRAS, Volume 394, Issue 4, pp. 1945-1955.
"Gravitational Wave Astronomy Using Pulsars: Massive Black Hole Mergers & the Early Universe", Demorest, P.; Lazio, J.; Lommen, A.; Archibald, A.; Arzoumanian, Z.; Backer, D.; Cordes, J.; Demorest, P.; Ferdman, R.; Freire, P.; Gonzalez, M.; Jenet, R.; Kaspi, V.; Kondratiev, V.; Lazio, J..; Lorimer, D.; Lynch, R.; McLaughlin, M.; Nice, D.; Ransom, S.; Shannon, R.; Siemens, X.; Stairs, I.; Stinebring, D.; Reitze, D.; Shoemaker, D.; Whitcomb, S.; Weiss, R. (2009) Astro2010: The Astronomy and Astrophysics Decadal Survey, Science White Papers, no. 64
"X-ray Timing of Neutron Stars, Astrophysical Probes of Extreme Physics", Arzoumanian, Z.; Bogdanov, S.; Cordes, J.; Gendreau, K.; Lai, D.; Lattimer, J.; Link, B.; Lommen, A.; Miller, C.; Ray, P.; Rutledge, R.; Strohmayer, T.; Wilson-Hodge, C.; Wood, K. (2009) Astro2010: The Astronomy and Astrophysics Decadal Survey, Science White Papers, no. 6
"Correlation Between X-Ray Light-Curve Shape and Radio Arrival Time in the Vela Pulsar," Lommen, A., Donovan J., Gwinn, C., Arzoumanian, Z., Harding, A., Strickman, M., Dodson, R., McCulloch, P., and Moffett, D. (2007) ApJ 657: 436.
"Interstellar Plasma Weather Effects in Long-term Multi-frequency Timing of Pulsar B1937+21," Ramachandran, R.; Demorest, P.; Backer, D. C.; Cognard, I.; Lommen, A. (2006) ApJ 645:303.
"Arecibo Pulsar Survey using ALFA. II. The young, highly relativistic binary pulsar J1906+0746," Lorimer, D. and 36 co-authors (2006) ApJ 640: 428.
"Arecibo timing and single pulsar observations of 17 pulsars," Champion, D. J.; Lorimer, D. R.; McLaughlin, M. A.; Xilouris, K. M.; Arzoumanian, Z.; Freire, P. C. C.; Lommen, A. N.; Cordes, J. M.; Camilo, F. (2005) MNRAS 363:929.
"Pulsar timing and the detection of black hole binary systems in globular clusters," Jenet, F., Creighton, T. and Lommen, A. (2005) ApJL 627: 125.
"Masses, Parallax, and Relativistic Timing of the PSR J1713+0747 Binary System," Splaver, E.M., Nice, D.J., Stairs, I.H., Lommen, A.N., and Backer, D.C. (2005) ApJ 620: 405.
"Constraining the properties of supermassive black hole systems using pulsar timing: application to 3c66b," Jenet, F.A., Lommen, A.N., Larson, S.L., and Wen, L. (2004) ApJ 606: 799.
"PSR J0609+2130: a disrupted binary pulsar?" Lorimer, D.R., McLaughlin, M.A., Arzoumanian, Z., Xilouris, K.M., Cordes, J.M., Lommen, A.N., Fruchter, A.S., Chandler, A.M., and Backer, D.C. (2004) MNRAS 347:L21.
"PSR J1740+1000: A Young Pulsar Well Out Of The Galactic Plane," McLaughlin, M.A., Arzoumanian, Z., Cordes, J.M., Backer, D.C., Lommen, A.N., Lorimer, D.R., Zepka, A.F. (2002) ApJ 564: 333 . (astroph 0106371).
"X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - The Final ROSAT Observation," Becker, W., Trumper, J., Lommen, A., & Backer, D., (2000) ApJ 545: 1015.
"RXTE Absolute Timing Results for the Pulsars B1821-24 and B1509-58," A.H. Rots, K.Jahoda, D. J. Macomb, N. Kawai, Y. Saito, V.M. Kaspi, A.G. Lyne, R. N. Manchester, D.C. Backer, and A. L. Somer, D. Marsden, and R. E. Rothschild (1998) Ap.J., 501, 749 .