Towards a Census of Supermassive Black Hole Masses

A group of astronomers and astrophysicists based at the University of Arkansas (both the Fayetteville and Little Rock campuses) have come together to bring a range of expertise to bear on this important problem.

Daniel Kennefick (left above), a member of the Space Center and a faculty member in the department of Physics at the Fayetteville campus, is a theoretical astrophysicist specializing in the modeling of gravitational waves from supermassive black holes. Julia Kennefick, a member of the Space Center and a faculty member in the department of Physics at the Fayetteville campus, is an astronomer specializing in quasars. Claud Lacy, a member of the Space Center and a faculty member in the department of Physics at the Fayetteville campus, is an astronomer specializing in binary star systems.

Marc Seigar (left below), a faculty member in the department of Physics and Astronomy at the Little Rock campus, is an astronomer specializing in galactic structure. This group aims to try to exploit new and existing methods to greatly expand the number of supermassive black hole masses which have been estimated and measured. They have recently been awarded a NASA EPSCoR exploratory grant in Arkansas to pursue their ideas.

One of the most significant advances in astronomy in the last quarter century has been the accumulation of evidence that the centers of most or all galaxies are inhabited by supermassive black holes (often abbreviated SMBHs), which have masses of between a hundred thousand to over a billion times the mass of our Sun. Several dozen of these behemoths have been identified and their size estimated by observations of stars or dust in orbital motion around them. Our own galaxy turns out to have such a giant (in the constellation Sagittarius, as seen from Earth), which has been weighed, through observations of stars in orbit around it, at some 3.7 million Solar masses.

Since accretion disks of gas and dust around supermassive black holes have long been believed to be the energy source of quasars and other active galactic nuclei, the discovery of these supermassive black holes in normal galaxies suggests that all galaxies went through a period when their central cores or nuclei were immensely bright, far outshining all the stars in the galaxy put together, but have now become quiescent. The study of these enormous objects will be of great significance for both cosmology and the study of the birth, formation and evolution of galaxies.

In addition, supermassive black holes should be ideal sources for a space-based gravitational wave detector such as the proposed NASA/European Space Agency mission LISA (Laser Interferometer Space Antenna).  Occasional scattered stars will stray close enough to enter orbits which produce significant amounts of gravitational radiation. This radiation carries away energy and momentum from the orbiting star, making it to spiral in towards the central black hole.  Eventually it plunges into the black hole with a final strong train of gravitational waves which should be observable by LISA even from galaxies in distant galactic super clusters. An even more exciting event, which could be observed by LISA at cosmological distances, would be the merger of two supermassive black holes, which could be the sequel to the merger of two galaxies, something astronomers observe to be quite a common even in our universe.

A few years ago NASA flew a mission called STARDUST to comet Tempel to collect cometary particles for return to Earth. A few months ago, the Space Center submitted a proposal to NASA to study the particles in its laboratories at the University of Arkansas. NASA recently announced its intention to fully fund the proposal at $425,000 for three years. The critical element in the successful proposal was work by SPAC graduate students Fatemeh Sedaghatpour and Jonathan Craig that established that we had the capabilities to handle and analyze such tiny particles. The cometary dust grains are microscopic in size and may contain information about their history and the origin of the solar system. The researchers use a technique developed at the University of Arkansas for studying the thermal and radiation histories of extraterrestrial materials called thermoluminescence in which particles are heated in the dark and the glow produced is measured by highly sensitive equipment. The work will be performed in newly constructed clean rooms in the old museum building.

Photo caption: Fata Sedaghatpour and Jon Craig

The Space Center announces the appointment of a Planetarium Student Oversight Board to manage and maintain the planetarium as an integral element of its astronomy education efforts. The planetarium is a joint project with the department of physics and will be used in daytime astronomy lab-oratory classes, night laboratory on clouded nights, and lecture courses. The planetarium structure is complete. The projector, purchased by the Space Center and the physics department with major contributions from the College of Engineering and the Sam Walton College of Business, is installed and working. The Board will now bring the software on line and it will design presentations required by the education courses. Once up and running smoothly for the astronomy courses, the plan-etarium will be available to support other courses around the university.

Photo caption: (from left) Adam Hughes (Chair of the Board), Scott Barrows, Katie Bryson, Kathy Gietzen. Not pictured: Kate Coleman

Solicited Research Programs (In Order of Proposal Due Dates)

Workshop on Martian Gullies: Theories and Tests
February 4-5, 2008
Lunar and Planetary Institute
Houston, TX
Abstract Deadline: 11/13/07

Lunar and Planetary Science Conference
March 10-14, 2008
League City, TX
Abstract Deadlines: 01/08/08 - (PDF format)
or 01/03/08 (all other formats - 5:00 pm CST)