Women in the High Energy Universe

Karla Guardado

Karla Guardado is an astrophysicist technical assistant at the Smithsonian Astrophysical Observatory. She studied physics at MIT and wrote her thesis on “Preheating in New Higgs Inflation.”

I wanted to go into a career in astrophysics because I fell in love with space--its marvels and secrets. As I learned increasingly about physics in school, I became more and more inquisitive. It seemed like the more I thought I knew, I realized that there were actually so many more questions to be answered. I always had an affinity with science, but it was the desire to discover these unanswered questions about space that led me to a career in astrophysics.

I became interested in science at a very young age. I was always very inquisitive, but it wasn't until I began putting the scientific method to use that I understood what science could achieve. I loved every part of my science projects, the investigation, experimentation, and drawing conclusions. That was how I began to think of science as a future career.

Illustration: NASA/CXC/K.Divona

Last month, I was honored to attend an extraordinary event: the United State of Women Summit convened by the White House. Since the word "summit" means a pinnacle, this couldn’t have been more appropriate for how I viewed this day and the amazing attendees I was able to share it with.

The United State of Women Summit brought together leaders in all different professional fields – from politics to entertainment, from science to finance. The common thread among all of the participants, however, was easy to find: everyone there wanted to continue to foster and enhance the opportunities for girls and women in whatever endeavors they may choose to pursue.

We are pleased to welcome Bailey Tetarenko as our guest blogger. She is the lead author on a paper featured in our latest press release about a possible new population of black holes in the Galaxy. Bailey received her undergraduate degree in Astrophysics at the University of Calgary and then a master’s in Physics at the University of Alberta in 2014. She is now two years into her Ph.D. in Physics at the University of Alberta, where she is studying the black hole population of the Milky Way.

From right to left Bailey Tetarenko, Dr. Arash Bahramian and Dr. Craig Heinke and Dr. Greg Sivakoff. Credit: John Ulan

For fans of black holes, we live in exciting times. Nearly all of our empirical knowledge about stellar mass black holes – that is, black holes weighing about 5 to 35 times the mass of the sun – comes from black hole X-ray binary systems. In these systems a black hole pulls in material from a nearby companion star, causing the system to become very bright in X-rays. But, recently gravitational waves have been detected from pairs of distant black holes that emit no electromagnetic radiation (a.k.a. all forms of light). And now, my team's work suggests that there are many black hole X-ray binaries in our own Milky Way that emit relatively little X-rays.

Illustration: NASA/CXC/K.DiVona

Click here to watch the recent TED talk for this feature!

Objects in space are rather far away. The Moon is our closest celestial neighbor at nearly a quarter million miles from Earth, and the nearest star, our Sun, is 93 million miles away.

These extreme distances mean that it’s usually impossible to touch real objects in space (meteorites that fall to the ground not withstanding). Advances in both astronomy and technology, however, now allow you to do the next best thing: hold a 3-D model of one based on real data.

The story behind such a remarkable feat starts with how astronomers study space. Unlike previous generations of sky gazers, today’s astronomers look at the Universe in many kinds of light, across the full electromagnetic spectrum. Through advanced telescopes and detectors, scientists can “see” from radio waves to gamma rays. Why is this important? We need to look at the Universe in all the types of lights to even begin to understand it.

Take X-rays, for example. Back in 1999, NASA’s Chandra X-ray Observatory was launched in order to observe the high-energy Universe including such things as colliding galaxies, black holes, and supernova remnants.

One such supernova remnant that Chandra studies is Cassiopeia A. About 400 years ago, in our own Milky Way galaxy, a star that was about 15 to 20 times the mass of our Sun, detonated in a supernova explosion.

Micro to macro
Illustration: NASA/CXC/K.Divona

When people ask me what I do for work, I often say that I’m a storyteller. It’s not that I stand on a stage with a microphone and narrate long tales to a rapt audience.

My stories are told differently, not through voice or music, but through lines of code and technical applications. They are stories, of science.

As an undergraduate, I began my career in molecular biology, looking at the tiny organisms that can transmit Lyme disease to humans aboard the Ixodes Scapularis (a.k.a., the Deer tick). But by the time I graduated, I was moving on to learn about another type of science: that of computers.

Alicia Goldstein

We welcome Alicia Goldstein, who was an intern at the Chandra X-ray Center this past summer, as our guest blogger. Ms. Goldstein, originally from Ellicott City, MD, is currently a senior at the University of Maryland, Baltimore County where she majors in mechanical engineering. Prior to this summer, Ms. Goldstein was an intern at NASA’s Goddard Space Flight Center and lists working for NASA as her ideal career goal.

This summer, I worked on two separate projects. The first involved the development of a Python code that would display the defined and predicted positions and velocities of Chandra, and the second involved the analysis of the periods of the variable stars in the Chandra Variable Guide Star Catalog,, or VGuide, database. The coding project involved interpreting and manipulating previous code, as well as creating entirely new sections. Given an input of two data files, the code was able to output a file with plots of the predicted and defined velocities and positions of the spacecraft.

Vivienne Baldassare

We are very pleased to welcome Vivienne Baldassare as a guest blogger today. Vivienne is the first author of a paper that is the subject of our latest press release, about an exceptionally small supermassive black hole. She is a PhD candidate and National Science Foundation Graduate Research Fellow in the University of Michigan Department of Astronomy. Vivienne obtained her undergraduate degree in physics from Hunter College, where she was also a member of the Macaulay Honors College.

It is well established that most, if not all, massive galaxies host supermassive black holes at their centers − our own Milky Way houses a several million solar mass black hole in its core. Little is known, however, about the population of black holes in the centers of dwarf galaxies. I study the centers of small galaxies to see how many host supermassive black holes and if those black holes interact with their galaxies in the same way as bigger supermassive black holes.

Though dwarf galaxies are more common than large galaxies, it is more difficult to determine whether they host black holes. When galaxies are large and nearby, we can find central black holes by studying the motions of stars in the region dominated by the gravity of the black hole. Since smaller black holes influence smaller regions, this method would only work for dwarf galaxies in our cosmological back yard. Instead, we must search for active black holes in dwarf galaxies, i.e. black holes that are voraciously consuming material, releasing large amounts of light from the galaxy’s center.

There have been so many excellent images and messages being tied to the hashtag #girlswithtoys on Twitter over the past several days. We would love to be able to take some selfies with some of the many female scientists, engineers, and other professionals who use and run the Chandra X-ray Observatory. (Of course, the Director of Chandra is Belinda Wilkes, the first woman to lead one of NASA’s Great Observatories) Unfortunately, Chandra is currently in its highly elliptical orbit that takes it a third of the way to the Moon, so the spacecraft is unavailable for a snapshot.

Mar Mezcua

We are pleased to welcome Mar Mezcua as a guest blogger today. She led the study that is the subject of our latest press release, about an intermediate mass black hole. Mar is from Balaguer (Lleida, Spain) and studied Physics in the University Autonomous of Barcelona and in the University of La Laguna, where she also specialized in Astrophysics. She completed her PhD at the Max-Planck-Institut fuer Radioastronomie (Bonn, Germany) in 2011 and then moved to the Instituto de Astrofisica de Canarias (Canary Islands, Spain) as a postdoctoral researcher. She is currently a postdoctoral researcher at the Harvard-Smithsonian Center for Astrophysics.

I found my calling when I was 13 years old and serendipitously watched a documentary on TV about galaxies and supermassive black holes. I wanted to become an astrophysicist and study these exciting objects!

Supermassive black holes reside at the center of galaxies and are more than a million times more massive than the Sun. As their name implies, they are black and thus cannot be observed directly. Hence, to detect black holes we have to observe the matter that surrounds and feeds them, this is, the material that the black hole “accretes.” In supermassive black holes, this accreting material heats up high enough to emit X-rays so that we can detect it with X-ray satellites like NASA’s Chandra X-ray Observatory. Some supermassive black holes also eject outflows of plasma or jets, which emit mainly at radio wavelengths.