Giant Elliptical Galaxies

Our own Milky Way is huge at 100,000 light years across, yet is dwarfed by the so-called giant elliptical galaxy which can be up to ten times its size.

Giant ellipticals are the biggest galaxy type of them all. Curiously, giant ellipticals are always situated in the denser regions of space. They are framed by up to hundreds of other galaxies. Each one of these other galaxies has its own 10-100 billion stars replete also with star forming gas and a supermassive black hole.

As the giant elliptical is so massive and thus has stronger gravity, these other smaller galaxies fall in toward the giant elliptical.

Like some bad science fiction movie about a "blob," the giant elliptical has a chance to grow by cannibalizing its smaller galaxy neighbors. The giant elliptical tears apart each nearby galaxy, separating out the stars from the gas, the dense nucleus, and the supermassive black hole.

Interestingly, the supermassive black hole is thought to settle quickly in the center of the giant elliptical which just 'ate' it, thereby growing the size of the cannibal's supermassive black hole stomach. As evidence that this cannibalization process actually happens, in some cases the remnants of 'undigested' galaxies can be spotted inside of giant ellipticals against the vast panoply of its constituent stars.

Given that giant ellipticals are the sites of violent collisions with slow cooling times and are situated in hot environments, such objects are thought to be unlikely places to form new stars. Even so, recently astronomers have found considerable amounts of cold gas typical of the sites of new star forming regions surrounding some giant ellipticals.

The cause is still unknown, with some led to believe that the large and growing supermassive black hole may provide a kind of thermostat which regulates the heating and cooling of the galaxy that surrounds it.

Dr. Brenda Frye

About Dr. Brenda Frye

Brenda L. Frye is an observational cosmologist at the Department of Astronomy/Steward Observatory, University of Arizona. She earned her Ph. D. in Astrophysics from the University of California at Berkeley, assisted by a National Science Foundation Graduate Research Fellowship.

Her thesis work involved measuring the concentration of the total mass of visible plus dark matter in the fields of massive galaxy clusters, a program requiring the use of some of the largest telescopes in the world.

Moving a mile from her Ph. D. institution, she assumed a postdoctoral position with the Supernova Cosmology Project at Lawrence Berkeley National Laboratory under the direction of Professor Saul Permutter.

She then treked across the country to take a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship and a Princeton Council on Sciences and Technology Fellowship both at Princeton University.

Moving further east, she became a Lecturer in Physics at Dublin City University in Dublin, Ireland, where a number of European collaborations were formed.

From there she crossed back across the pond to the west coast of the U. S. to become a tenure-track Assistant Professor of Physics at the University of San Francisco.

Her travels have now landed her at her Alma Mater in Tucson, where she teaches and does research. The aims of her research continue to be to use gravitational telescopes in space as 'lenses' to study the properties of dark matter and those of distant galaxies back to when the universe was <900 million years old.

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Giant Elliptical Galaxies — 1 Comment

  1. Pingback: Giant Elliptical Galaxies – Observatorio Astronómico del Vaticano comunidad religiosa de la Compañía de Jesús en Castel Gandolfo

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