Andrea Lommen's Research and Publications
Dr. Lommen's research interests
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 am currently chair.
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.
2008 March: F&M's article on my NSF CAREER Grant. This also contains a brief description of the outreach program I am starting in high schools here and in Australia.
2002 January: Press Release on Pulsar Timing Array, UC Berkeley.
The Ripple Effect, New Scientist. 2002 Jan 18;
USA Today, 2002 January
At right you see Michael Johnson. a UCSB graduate student who is working 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.
Recent Publications
(Student co-authors are designated in red. Clicking on the name will take you to a description of their work on my Student Project Page.)
"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.
"Parallax and Proper Motion of J0030+0451," Lommen, A.N., Kipphorn, R.A., Nice, D.J., Splaver, E.M., Stairs, I.H., and Backer, D.C. (2006) ApJ 642: 1012.
"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.
"Using Pulsars to Detect Massive Black Hole Binaries via Gravitational Radiation: Sagittarius A* and Nearby Galaxies, " Lommen, A. N., Backer, D.C., (2001) ApJ 562: 297 . (astroph 0107470).
"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).
"New Pulsars from an Arecibo Drift Scan Search," Lommen, A. N., Zepka, A., Backer, D.C., McLaughlin, M., Cordes. J. C., Arzoumanian, Z., Xilouris, K., (2000) ApJ 545: 1007 . (astroph 0008054).
"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 .
