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.

Is Our Galaxy a Rebel?

We are particularly fond of the Milky Way because it is the home of the Sun and the Earth (as well as another 100 billion other stars and still more planets). The Milky Way forms the cornerstone against which we base our understanding of how other galaxies might work in detail. The question is: can the Milky Way be described as a typical spiral galaxy? There are a few signs that the Milky Way may be a bit different from its neighbors. One clue comes from looking at the galaxy centers. All massive spiral galaxies like the Milky Way are found to harbor giant black holes, except that for the Milky Way this central supermassive black hole is smaller. Another clue comes from an investigation of the surroundings of spiral galaxies. The Milky Way has dozens of very small galaxies in its immediate vicinity which we call satellites. Many of these satellites have been discovered only very recently as they … Continue reading

The Footprints of Reionization

The emergence of the first stars in the universe must have been quite a spectacular sight. The standard lore is that the first stars were probably massive, bright, and short lived. As remarkable as these stars must have been, as well as the second generation of stars to follow them, they would all have died very young, exploding only a scant million years after they formed. Fortunately for us, they left behind traceable signatures of their existence. You see, the bright light from these stars shone to vast distances in all directions. Wherever the light encountered a hydrogen atom, which was very nearly everywhere, it would remove the electron from that atom. It would ionize that hydrogen atom. The ionized hydrogen would surround the star out to large distances. As an analogy, imagine unknowingly walking across a a sidewalk filled with wet cement. Your footprint would be embedded in the drying concrete. Long after you left the scene to buy … Continue reading

Globular Clusters and Black Holes: Detection!

We return to the topic of the humble globular cluster, an object that usually draws little attention as it consists of a clump of about a million very dim stars. One aspect of globular clusters that is interesting is that all of these stars are enclosed in an incredibly small space. As an analogy, imagine substituting stars in the sky with administrators in an office. Let us say that your task is to house 10 administrators You could choose to give them each their own desk space in a large room, or you could to save on space and crush them all into a small elevator for eight hours per day. The former case is similar to that of the Milky Way. In the Milky Way, each star (administrator) is sitting in a part of sky (a desk) that is spaced a comfortable distance from the other stars (administrators). Thus when we look up at the sky at night, we … Continue reading

Globular Clusters and Black Holes

Keeping up with an interest amongst VFO readers, we turn now to a discussion on globular clusters. These dense concentrations of about a million stars all in rapid orbit about each other had been notoriously uninteresting, that is until recently. It seems that globular clusters may be the most efficient place to form a closely-attached pair of black holes called a “binary black hole”. Let us see how this curious arrangement may have come about. The standard lore had been that any black holes formed in a globular cluster would get thrown out on the grounds that they did not “mix” well with the other normal shining stars. The result would be a globular cluster devoid of black holes. Recently, using computer simulations that assign more realistic masses to the black holes of 3 – 80 times the mass of the sun, multiple research groups are finding that dozens to hundreds of black holes are retained within the globular clusters. … Continue reading

Black Holes Going Down the Drain

Ever wonder what happens to a black hole at the end of its life, if such a thing can be said for a black hole? Does it sit there unchanging, or perhaps have a different end state? Physicist Steven Hawking put forth the idea that the fate of a black hole is essentially the same as that of a drop of water on a countertop: in both cases over time they just evaporate away. Water evaporates because the molecules near to the surface are warmer than the other molecules on average. These warmer molecules also have higher energy and thus are able to leave the drop and escape into the air. Similarly, a black hole would also need to have matter (or equivalently light) escape. The conundrum facing physicists is that black holes are famous for not allowing any matter or light that enters its surface to be freed back into space. This is why they are called “black,” afterall. … Continue reading

Nature’s Beauty on Stage

Eclipses fascinate and inspire us. On Monday our daily routines will be interrupted by the passage of the moon directly in front of the sun that we call a solar eclipse. We will have no choice but to want to look up to take in the splendor of this relatively rare event in nature that will happen regardless of the work deadlines which time your next class starts on campus. A word of caution: please do NOT look at the eclipse directly. One will need ‘eclipse’ glasses to protect from harmful high frequency light from the sun’s outer layers that can destroy our retinas. Eclipses make for splendid excuses for doing science experiments. The stories are too many to recount here, so let’s narrow the discussion to famous experiments in the area of chemistry alone. For example, 1868 scientist Pierre Janssen viewed an eclipse through a prism. The prism broke up the light into a rainbow of colors called a … Continue reading

The Industrial Revolution for Galaxies (Part Two)

The fact that the Milky Way has a spiral shape tells us straight away that our Galaxy is situated in the suburbs. As an analogy, some people choose to live in the suburbs given the (typically) larger accommodations per unit cost and the relatively easy access to resources. Similarly, galaxies situated in groups (the ‘suburbs’) have relatively light interactions with neighboring galaxies as well as reasonable access to “galaxy food” (hydrogen) infalling from their surroundings. By contract, the galaxies packed into tight spaces (clusters) must cope with some rather aggressive interactions which usually involve two galaxies tearing material off of each other by a process called “ram pressure stripping.” This has the effect of wearing away that beautiful spiral pattern in Galaxy images. At worst, the galaxy interactions lead to mergers, in which one galaxy joins with another one. In this case, the spiral pattern disappears utterly. We cannot leap out of the Milky Way and look down onto our … Continue reading

The Industrial Revolution for Galaxies (Part 1)

When one looks at a deep image of the distant universe using the Hubble Space Telescope, a myriad of galaxies fill the field of view. Some galaxies sport elegant spiral shapes, others take on giant 3D oval (ellipsoidal) shapes, and still other have no discernible shape at all. On small scales galaxies appear to be put down haphazardly with all possible orientations and distances away from us. It is only when one takes a step back to view this panoply of objects thousands or even millions at a time, that we see that the arrangement is far from random. On larger scales, galaxies form a kind of 3D spider web which we call the “cosmic web.” These objects with 10 billion stars each have a tendency to collect at the junctures or “nodes” of the cosmic web. These galaxies that “grow up in the city” are seen to have a very different course of evolution compared to those that reside … Continue reading

Space is mind-bogglingly big

Writer Douglas Adams says space is mind-bogglingly big. Here is perhaps an interesting facet for thinking on this topic. Imagine sitting at one end of a room in which at an appointed time a friend enters from the far side. Now imagine that you look and look but cannot see this friend when they first enter, no matter how hard you squint your eyes. After a while, the person does appear to walk into the room, but the information is delayed from the time at which it actually happened. We are not familiar with such experiences. It does not happen to us on Earth only because of the small size of our planet, but it does happen in outer space. The reason for this ‘optical illusion’ has to do with the properties of light. Our eyes know that a friend is present only when light from a light bulb, or sunlight coming in through a window, bounces off of that … Continue reading

To a Big Telescope Luminary

Many years ago I was lucky enough to conduct student research at the Keck Observatories, atop the 14,000 foot peak of Mauna Kea, Hawaii. This is the site of the largest optical telescope in the world. On one of my return flights, coincidentally I found myself sitting next to Professor Jerry Nelson, whose work was largely responsible for existence of this spectacular observatory! I asked many questions which he was willing to entertain without hesitation. If the accomplishments of this person stopped with the design of a big telescope then that would already be commendable. In this case, though, he also managed to overcome an obstacle blocking progress to building big telescopes. The story goes something like this. One can build larger and larger solid telescope structures only up to a certain size. Beyond a diameter of around 5 meters (or about 16 feet), the mirror approaches such a weight that it starts to sag until eventually the the ability … Continue reading

Hopscotching with Aliens?

There is a new initiative in the area of the Search for Extra-Terrestrial Intelligence (SETI). Although the SETI program has history of listening for deliberate (or accidental) messages from any potential advanced civilizations dating back more than 50 years now, we knowingly transmit messages less than 1% of that time. Indeed some long wavelength transmissions such as TV programs do manage to leak into space, but they are too faint to decipher across interstellar distances. In all that time we have never received a message from aliens. There is also no evidence at all that aliens have ever visited us. Space appears to be empty. Does this mean other intelligent creatures do not exist at all? The struggle to answer that question has motivated a new initiative called the Messaging Extra Terrestrial Intelligence (METI). The aim is to take action to send messages in the direction of known planetary systems. Most people at this point ask, “Is this exciting?, or … Continue reading

The Dark Energy Spectroscopic Instrument (DESI)

This week there is a large gathering of extragalactic astronomers here at at Lawrence Berkeley National Lab (LBNL) to attend a conference on the Dark Energy Spectroscopic Instrument (DESI), a new experiment that will be commissioned on a large telescope on Kitt Peak National Observatory (KPNO) in Arizona. With a team now 500 people strong, the focussed goal is to measure the relative positions and orientations of millions of galaxies in order to study properties of the early universe. One can get at a straightforward understanding of this project by considering galaxy shapes. Galaxies are complicated objects with billions of stars. Even so, from a distance galaxies mostly take on oval shapes. These oval-shaped galaxies that we see on a typical pictures can face any which way. This turns out to be the case when one views galaxies within regions of space in which one can see only hundreds of examples at a time, but not millions. On such scales … Continue reading