I am a
junior faculty member at
the University of Washington in the physics
department. The above photo is of my RadCos (radio cosmology)
research group (left to right): Amy Kimball, David Wright,
Adam Beardsley, Ken Odenberger, Adrienne Stilp, Bryna Hazelton, Patti
Carroll, Christian Boutan, Brynn MacCoy, and Alex Bastidas Fry.
research interests fall into three related areas: observational
cosmology, the transient universe, and the development of the advanced
hardware and software needed for emerging astrophysics observations.
Over the past few years I have developed several new radio cosmology
signatures and I’m currently working on the construction of the
Murchison Widefield Array (MWA)
and GASE array, and the design of the CARPE.
Much of my
research concentrates on Epoch of
Reionization (EoR) observations. The cosmic microwave background (CMB)
shows us that the early universe was very, very smooth, while today
matter is clumped into galaxies and clusters separated by enormous
voids. The process of galaxies and stars coallescing out of the smooth
early universe is called structure formation, and we would like to
study the first stars and galaxies as they form to help us understand
how the structure we see around us formed.
Unfortunately, seeing the first galaxies and stars as they turn on is
very hard. Just after the image of the smooth early universe we see in
microwave background, the hydrogen filling the universe becomes
neutral. Since neutral hydrogen absorbs the light we can detect with
optical telescopes, we can only see galaxies after this fog of
neutral hydrogen has burned off at redshifts smaller than about six.
Because of the absorption by neutral hydrogen, the time between the
smooth microwave background at a redshift of 1089 and the clumpy
galaxies and quasars at a redshift of 6 is largely unexplored, and has
become known as the “cosmic dark ages.” The end of the
cosmic dark ages is called the Epoch of Reionization, and fortunately,
neutral hydrogen has a faint spectral line at radio frequencies. By
observing this faint radio signal from the neutral hydrogen we can
observe the formation of galaxies and the ignition of the first stars
and quasars at the end of the cosmic dark ages.
Observing the EoR requires new observational capabilities, and I am one of the principal designers of the Murchison Widefield Array. The MWA will consist of 512 fully cross-correlated antennas in a compact 1.5 km diameter array, and is currently under construction at the very remote Murchison Radio Observatory in the western Australian desert. Full cross-correlation of all antenna pairs provides a very large ~30° field-of-view (survey speed) and excellent instantaneous visibility coverage (PSF quality), both of which are required to achieve the sensitivity and systematic error control needed for the EoR. The photo above is from a November 2008 trip to commission the prototype (I'm next to one of the 32 antennas of the prototype, and others can be seen in the distance, more photos from the trip). The images below are from data taken during the November trip. The left one shows many sources surrounding the bright radio galaxy Pictor A (note the image is 30° across!), and the right image shows the extended emission from the Puppis A super nova remnant.
the faint EoR signal from the strong astrophysical signals (like
galaxies and super nova remnants) will require
advances in data analysis and foreground removal techniques. We have
extended the CMB style analyses to utilize
the line-of-sight information and the symmetries inherent in the EoR
signal. This three-dimensional statistical analysis significantly
improves the sensitivity of radio arrays to the EoR structure. I recently wrote a
review article with Stuart Wyithe for Annual Review of Astronomy and
Astrophyscis on 21 cm
Epoch of Reionization and dark energy observations that can be found here. I am
also leading the effort to subtract the foreground emission and reveal
EoR power spectrum signal with MWA observations, and have the pleasure
working with an extraordinarily talented team of
US, Australian, and Indian scientists including Jacqueline
Hewitt, Judd Bowman, Max Tegmark, Bryan Gaensler, Frank Briggs, Stuart
Wyithe, Matias Zaldarriaga, Angelica de Oliveira-Costa, and many
out that approximately 3% of the hydrogen in the universe remains
neutral after reionization (principally in small DLA galaxies). This
might enable the efficient measurement of the expansion history of the
universe and dark energy with specially designed interferometers. I am
working with Maura McLaughlin, David Kaplan, Rich Bradley, and Judd Bowman to design
telescope which focuses on measuring the size of the universe from
redshift 1–3.5 via baryon acoustic oscillations and gravity waves via
precision pulsar timing.
On a much smaller scale than the MWA or CARPE, I am working with a small team at MIT and the Naval Research Laboratory to build GASE (pronounced “gaze”). This little (less than $50k!) interferometer consists of eight dipole antennas, and will search for the highly dispersed prompt gamma ray burst emission that is predicted to exist near 30 MHz (Judd and Jackie digging out one of the antennas in the picture to the left). In addition to providing unique science observations, GASE also serves as a pathfinder for wide field transient detection techniques with the MWA and the Long Wavelength Array.
Many of the hits to this web site probably still come from visualizations I did as a graduate student at UC Santa Cruz back when I worked in particle astrophysics. The movies of extensive air showers and their interactions with the Milagro detector have become popular in the TeV gamma ray community. Please visit the Milagro Animations web site to see these movies (they're pretty cool to watch).
Email me for any reason that strikes your fancy. My office is in the Physics Astronomy Building C525 if you would prefer to swing by.
-Miguel F. Morales