Spotlight on Gabriel Barnes Brammer, ESA/AURA Astronomer

This occasional series focuses on members of the Frontier Fields team. It highlights the individuals, their jobs, and the paths they took to get to where they are today.

Portrait of Gabriel Brammer

Astronomer Gabriel Brammer answers questions about his role on the Frontier Fields program and the path he took to get there.

What does a typical day on the job entail? What are your responsibilities?

A typical day involves a lot of communication: e-mail and teleconferencing with scientific collaborators around the U.S. and around the world, assisting observers with preparing their Hubble observations, and conversations and meetings with fellow members of the Hubble Wide Field Camera 3 instrument team. My research focuses on the formation and evolution of distant galaxies, often using Hubble observations. I have a position that allows me to pursue my own independent research interests along with my responsibilities supporting Hubble operations, and I appreciate that the goals of both of these aspects of my work are closely aligned.

 What specifically is your educational background?

I obtained a bachelor’s degree in astronomy from Williams College in Williamstown, Massachusetts, and a Ph.D. in astronomy from Yale University in New Haven, Connecticut.

 How did you first become interested in space?

My favorite subjects in school were always math and science, particularly physics when I was a bit older. Reading Carl Sagan’s “Cosmos” in high school always sticks with me as being a defining moment in inspiring my interest in space science and astronomy. Sagan presents such a clear connection between the beauty of the subject and the rigorous science that underlies it; I’ve seen from other profiles of my colleagues similar to this one that I’m far from alone in finding inspiration there!

Was there someone (parent, teacher, spouse, sibling, etc.) or something (book, TV show, lecture, etc.) that influenced you in developing a love for what you do, or the program you’re a part of?

The pursuit of an advanced degree in astronomy, or any field, is a very long chain that stretches over 20 years of a student’s life, obviously including a dramatic evolution in his or her own personal development and maturity. From day one I’m grateful for the tireless love, support, and encouragement from my parents and family, and I have had many excellent teachers, mentors, and role models at all stages of my education and career. Each of them represents a strong link in that chain, and without any one of them individually, the path I would have taken would likely have been very different from the one I am happy and honored to be on today.

Was there a particular event (e.g., lunar landing, first Shuttle flight, etc.) that particularly captured your imagination and led to life changes?

 The bright appearance of Comet Hale-Bopp in the winter of 1997, my junior year of high school, was a formative event for me at an opportune moment. Seeing the bright comet, a transient visitor from the outer solar system, just hanging over the horizon captivated me. As often as I could, I would drag the small telescope my dad had recently bought, along with as many friends I could muster, out to the cold, dark skies of central Iowa to see it.

Later in the summer of ’97, I went to New England to tour potential colleges, where, during a short visit to Williams College, I met Professor Jay M. Pasachoff and his students who were preparing an expedition to observe the solar eclipse in Aruba the following year. That brief encounter, along with the recent experience observing Hale-Bopp, showed me that studying astronomy would offer an ideal combination of research in the physical sciences and travel to exotic locales to observe both aesthetically and scientifically magnificent phenomena. I was privileged to later study and research with Professor Pasachoff myself, including an unforgettable expedition to observe the solar eclipse in Lusaka, Zambia, in 2001.

Gabe checks out the telescope for observations of the June 21, 2001, total solar eclipse from Lusaka, Zambia, as part of the Williams College Eclipse Expedition. Credit: J. Pasachoff.

Gabe checks out the telescope for observations of the June 21, 2001, total solar eclipse from Lusaka, Zambia, as part of the Williams College Eclipse Expedition. Credit: J. Pasachoff.

How did you first get started in the space business?

My first experience visiting and working at a professional astronomical observatory was with the National Science Foundation’s Research Experiences for Undergraduates program at the Cerro Tololo Inter-American Observatory in 2001. I must say I was pretty miserably exhausted my first night observing up on the mountain top, ready to adjust my career plans at 4 a.m., with the local radio reminding us between cumbia (dance music) hits of the glacial progress of time — “son las cuatro con cinco minutes … son las cuatro con diez minutos.” I suppose the second night was a bit better, and by the third night I was hooked.

I’ve been working at observatories ever since, now having spent something like 270 nights observing the skies from mountain tops in Arizona (Kitt Peak) and Chile (Cerros Tololo, Las Campanas, and Paranal) to valleys in Japan (Nobeyama). Going outside at night at one of these observatories and seeing the eyes of giant telescopes staring up at the sky, gathering in photons from distant objects, is an extraordinary experience. I’m happy to now have a more normal sleep schedule at the Space Telescope Science Institute, but I appreciate still being close to the day-to-day operations of Hubble as an observatory and working on the front lines as photons from distant stars and galaxies hit the detectors.

A composite image of sunset and midnight at the Very Large Telescope at Cerro Paranal, Chile.

A composite image of sunset and midnight at the Very Large Telescope at Cerro Paranal, Chile. Each of the four domes houses a telescope with a primary mirror 8.2 meters (26.9 feet) in diameter. Credit: Gabriel Brammer.

What do you think of the Hubble results, or the impact that Hubble has on society? 

Even classmates in my kids’ pre-kindergarten classes know Hubble when they see it! Hubble has something for everybody, from atmospheres of extra-solar planets to the most distant galaxies, and therefore has had an immeasurable impact on society’s scientific imagination and curiosity.

Is there a particular image or result that fascinates you?

To me the Hubble Ultra-Deep Field /eXtreme Deep Field (HUDF/XDF) represents all of the past success of Hubble and points to the future potential of Hubble and its successors like the James Webb Space Telescope in a single image. Now including near-infrared observations by the Wide Field Camera 3, installed in 2009, the HUDF/XDF shows us galaxies across some 95 percent of cosmic history, from the first star-bursting seeds of galaxies to the assembly of more massive, more regular structures of galaxies more like those we see today. The Frontier Fields represent the most recent exciting extension of the legacy begun with the Hubble Deep and Ultra-Deep Fields.

The eXtreme Deep Field, or XDF.

The eXtreme Deep Field, or XDF, was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. The XDF is a small fraction of the angular diameter of the full Moon. Credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team.

 I also love browsing through Hubble’s spectacular high-resolution images of nearby galaxies. In the deep fields, we generally infer properties of galaxies based on small, barely resolved images of their structures, while images of local galaxies such as the mosaic of M82 show many of the myriad processes that form and shape galaxies in exquisite detail. It is through the combination of these resolved nearby studies and distant surveys that Hubble has made such a large contribution in our understanding of how galaxies form and evolve.

Mosaic image from Hubble of the magnificent starburst galaxy Messier 82 (M82).

This mosaic image from Hubble of the magnificent starburst galaxy Messier 82 (M82) is the sharpest wide-angle view ever obtained of this galaxy. M82 is remarkable for its bright blue disk, webs of shredded clouds, and fiery-looking plumes of glowing hydrogen blasting out of its central regions. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA). Acknowledgment: J. Gallagher (University of Wisconsin), M. Mountain (STScI), and P. Puxley (National Science Foundation)

Are there specific parts of the program that you’re proud to have contributed to?

I am happy to have helped make the Frontier Fields observations as deep and as efficient as possible to maximize the scientific return from extremely valuable observing time on Hubble. With only a relatively minor change to the observing strategy, taking extra care to avoid extra glare from bright foreground light from the Earth, we enabled the Frontier Fields to see ever fainter and more distant galaxies than otherwise would have been possible.

Photo taken by Gabe of Comet Lovejoy (C/2011 W3) and the European Southern Observatory’s Very Large Telescope at Cerro Paranal, Chile (December 22, 2011). Credit: Gabriel Brammer.

Photo taken by Gabe of Comet Lovejoy (C/2011 W3) and the European Southern Observatory’s Very Large Telescope at Cerro Paranal, Chile (December 22, 2011). Credit: Gabriel Brammer.

 

Also see “Spotlight on Jennifer Mack, Research and Instrument Scientist,”
 Spotlight on Dan Coe, ESA/AURA Astronomer,” and Spotlight on Tricia Royle, Senior Program Coordinator.”

Spotlight on Tricia Royle, Senior Program Coordinator

This occasional series focuses on members of the Frontier Fields team.  It highlights the individuals, their jobs, and the paths they took to get to where they are today.

Portrait of Tricia Royle

Tricia Royle, senior program coordinator, answers questions about her role on the Frontier Fields program and the path she took to get there.

What does a typical day on the job entail? What are your responsibilities?

When astronomers are granted time on Hubble, their program is assigned to a program coordinator to make sure the observations are feasible and schedulable on the telescope. When problems occur any time between acceptance and execution, it’s the program coordinator who helps get problems resolved. We act as liaisons between the various groups at the Space Telescope Science Institute (STScI) — science, operations, scheduling — and the observers — principal investigators and co-investigators. I tend toward the large-scale and long-term observations like Frontier Fields.

What specifically is your educational background?

I have a BSc in physics and astronomy from York University in Toronto, Ontario, Canada, and I have taken postgraduate courses in applied physics from Johns Hopkins University in Baltimore, Maryland.

What particularly interested you in school or growing up?  What were your favorite subjects?

I wasn’t particularly good at school in the early years and didn’t like the monotony of memorizing multiplication tables or writing out spelling words. In grade six, when the curriculum started to get interesting and turn more logic-based, I started to pay attention and actually enjoyed just about every class — except history, which still had too much memory work. In high school, it became clear that math and science were my favorites, though I still took a lot of English and arts courses because I enjoyed the creativity involved.

Tricia Royle poses with an astronaut at Kennedy Space Center.

Nineteen-year-old Tricia on her fifth or sixth trip to Kennedy Space Center in Florida. Tricia recalls, “It was pretty much the first place I asked to go every time I’d go to Florida. Eventually, my family just accepted it as higher priority than Disney World.”

How did you first become interested in space?

Growing up in a very rural area about an hour outside of Toronto, surrounded by farms and no streetlights, I had always been able to see the Milky Way, but I didn’t know much about what I was seeing. When I first read that our sun was a star and figured out that meant every star I was seeing was potentially someone else’s “sun,” it was pretty humbling. I wasn’t very old and I’m pretty sure I annoyed a lot of aunts and uncles with my new-found “discovery” that our sun is actually a star. I didn’t understand how they could talk about anything else if they knew how many suns there were in the sky! Weather and gas prices just didn’t seem important enough to warrant discussion when compared to my new sun/star revelation.

Was there someone or something that influenced you in developing a love for what you do, or the program you’re a part of? Was there a particular event that especially captured your imagination and led to life changes?

A lot of things happened when I was in my pre-teens and teenage years to push me toward space. I remember feeling intense sadness and disbelief after the Challenger disaster. I was in middle school, just starting to enjoy learning, and had a hard time dealing with the idea that a teacher who was supposed to go into space, then come back to share her experience with her classroom and other classrooms, now wasn’t coming back at all. I hadn’t realized before then how dangerous it was to launch a shuttle and couldn’t see past the loss of those seven astronauts to understand why anyone would take that risk.

A year or so later, Star Trek: The Next Generation came on TV, and it all started to make sense. I loved the scientific language and ideas in the show and the notion of “going where no one had gone before.” Traveling around on the Enterprise seemed like a dream come true, and I started to understand why someone would put everything at risk to go into space. Star Trek: The Next Generation was my first exposure to positive science fiction — not just doomsday aliens and robots — and it introduced me to the concept of just how much more might be out there and what might be possible. Hubble launched a few years after that, when I was in high school, and started sending back incredible images of real things that were actually out there, waiting to be found. It seemed to me that maybe a bit of the show was coming to life and I wanted to know more.

When it came time to choose a topic for my first high school term paper — it happened to be advanced chemistry — I decided it was a good excuse to find out more about all those suns/stars I had seen in the sky as a child, on Star Trek for the past four or five seasons and now coming down from Hubble. This seemed like a really good idea until my 10-page report was closer to 30 pages, and I still had several books to go through. Thankfully, I had a wonderful chemistry teacher who encouraged me to delve as deep as I wanted into the topic, but to choose something specific to keep the final paper under 15 pages so she could finish reading it in an evening. I chose to focus on the life cycle of stars, and that was the beginning of my intense curiosity about the science of space and the universe.

Tricia Royle posing at the sign at the entrance to Kennedy Space Center.

On a later trip, 21-year-old Tricia poses at the entrance to Kennedy Space Center.

How did you first get started in the space business?

The summer after my third year at York University, I worked with Dr. John Caldwell analyzing Hubble data on the low-mass stellar companions of larger stars. During that summer, he visited STScI and Johns Hopkins University to attend a conference and meet with his collaborators. I was invited to tag along. I imagine I looked a little — or a lot — lost and awkward standing among seasoned Hubble scientists and STScI employees in the auditorium after a talk. Fortunately, one of the Hubble data analysts took pity on me and invited me into her conversation. Lisa Frattare — now part of Hubble Heritage — became an instant friend and would later encourage me to apply to work at STScI after graduation.

I didn’t take her seriously, thinking there was no way a fresh-out-of-school job could be with something as huge as Hubble. But on a dare with one of my college roommates, we both applied for our unattainable dream jobs — I applied to STScI and he applied for a coaching job at the University of Hawaii. As luck would have it, I got an interview and came to work at STScI shortly after graduation as a program coordinator. Sadly, my roommate did not make it out to Hawaii.

Before I left York University, Dr. Caldwell described my new position at STScI as “the hot seat of astronomy,” which ended up being an understatement. Immediately after I started, I was working with and attending conferences with scientists I’d seen listed in textbooks. In my first two years, I had the opportunity to work with the Director of STScI — Robert Williams — and many others on the Hubble Deep Field to push the science limits of the telescope, and to join Lisa Frattare and Keith Noll on the Hubble Heritage Project to help make beautiful images from Hubble’s scientific data. I worked with Hubble Heritage for five years and still think it is one of those really great initiatives that highlights for everyone, not just scientists, what Hubble can do. All in all, not a bad start to a career in space.

What do you think of the Hubble results, or the impact that Hubble has on society? 

 I think people have started to take for granted the amazing images Hubble continues to allow scientists to take. It’s been up there for almost 26 years, which means there are a lot of kids and even adults who don’t know what it’s like to NOT have these observations sent down on a regular basis, or what it was like before Hubble helped solve some of the fundamental questions about the expansion of the universe and what is out there. I have two school-aged kids who just assume that Hubble has or will answer any question they may have about stars or galaxies. I don’t think it occurs to them that Hubble hasn’t always been and won’t always be around to do that.

The fact that it is such an ingrained part of the scientific and academic community says just how successful it has become. It’s like the Internet – it’s hard to remember what it was like before we had this way to find answers to our questions. I suspect Hubble’s archives and legacy programs will continue to provide answers, or trigger new questions, for a long time yet.

Is there a particular image or result that fascinates you?

The Ultra Deep Field, or UDF. I found out I was pregnant with my first child just after I started working as program coordinator for the UDF, and the UDF images were released while I was still in the hospital after delivering my daughter — so I will forever tie those two events together. But more than that, I still use the UDF image in my presentations, even though it is almost 12 years old, because it fascinates everyone who learns what they are really looking at. I ask people to look at that image and realize that what they are seeing aren’t individual stars, but galaxies. Then I ask them to keep in mind that this particular piece of sky was chosen because it was “boring,” and to further consider that everything they are seeing is contained within a patch of sky the size of the president’s eye on a dime, held at arm’s length. More than a few jaws drop at the implication. Seeing the UDF image triggers that realization in people, especially kids, of just how vast the universe must be easily makes the UDF my favorite.

Are there specific parts of the program that you’re especially proud to have contributed to?

I like the view from where I sit in Operations. I like watching a Hubble program develop from the initial science outline in the Phase 1, to a workable Phase 2, to a successfully executed set of observations. I especially love the large and multi-cycle programs — 47 Tuc, Hubble Deep Field, Ultra Deep Field, Andromeda, CANDELS, and now Frontier Fields. They allow me to work with people who have such a passion for what they do on these in-depth programs and challenge me to find new ways to get them the science they need.

Because repeat observers are assigned, when possible, to the same program coordinator each time they observe, that working relationship has a chance to grow cycle after cycle. Program coordinators tend to get very attached to the scientists they work with multiple times. I’ve been here since Cycle 6 and now we’re ramping up for Cycle 24, so the list of observers I claim as mine is pretty long, and I feel very protective of them and their observations, even if they’ve moved on to other program coordinators or even other telescopes.

What outside interests could you share that would help others understand you better?

A lot of what we do on Hubble can feel abstract and intangible, since we can’t actually go to the telescope or out in space to touch what we observe — so I like to do things that produce more tangible, immediate results. In addition to my love of reading and watching sci-fi TV shows, I do a lot of crafts to create something I can hold in my hand.

With most of my observers scattered around the country and internationally, I rarely see them in person. Giving talks about Hubble to schools and the more general public lets me connect the science to people. Being able to explain a Hubble image to someone without a science background and make it real for them, helps put into perspective that what I do at work on a daily basis can be inspiring and has results beyond the image itself. I want what we do at STScI and on Hubble to show people they can dream as big as they like because the universe is big enough to handle it.

Is there anything else that you think is important for readers to know about you?

I was one of only four female physics and astronomy majors in my first year at York University. Before classes even started, my academic advisor suggested that I might want to choose something easier than physics and astronomy, despite coming in with an A+ average in high school and scoring in the top 5 percent on the math assessment. Male classmates with B averages were not given the same suggestion to find an easier major.

In the years ahead, every test grade of mine that fell below an A – there weren’t many – brought up the question from others, and myself, as to whether I really should be there, whether I was good enough. It was a constant fight to prove to classmates, professors and myself that I deserved to major in physics and astronomy. It wasn’t enough that I wanted to be there and was passing my courses – I had to excel. Four of us started, but I was the only female graduate in physics and astronomy in my year.

I have a daughter and a son, still relatively young, but they’re starting to look at what they want to do when they finish school. Obviously I want them to do well, but my wish for both of them, and anyone else looking at what to do in their life, is that in whatever field they choose, they know that wanting to be there is enough and they don’t have to prove to anyone they deserve to follow their dreams.

 

Also see “Spotlight on Jennifer Mack, Research and Instrument Scientist
and “
Spotlight on Dan Coe, ESA/AURA Astronomer

‘Hubble’s Views of the Deep Universe’ – Public Lecture

On November 3, 2015, I gave a presentation called “Hubble’s Views of the Deep Universe”.  This presentation was to commemorate some of Hubble’s most influential observing campaigns during this 25th anniversary year.  Of course, I could not get to all of Hubble’s programs that observed the deep universe in just an hour.  For additional information, check out the science articles on the Hubble 25th website and, of course, keep checking back to this blog.

Dr. Brandon Lawton
“Hubble’s Views of the Deep Universe”

November 3, 2015

For two decades, the Hubble Space Telescope has pioneered the exploration of the distant universe with images known as the “deep fields”. These deep fields have given astronomers unprecedented access to understanding how galaxies form and develop over billions of years in the history of our universe, from shortly after the Big Bang to today. Join us for a retrospective view of Hubble’s contributions to the investigation of the deep reaches of the cosmos and some fresh glimpses of what Hubble is currently doing to further our understanding of the most distant parts of the universe.

This lecture is part of the monthly public lecture series at the Space Telescope Science Institute in Baltimore, Maryland. Each month addresses a different cosmic topic, usually related to Hubble, but always venturing to some fascinating part of the universe. For more information, check out the web page on HubbleSite:
http://hubblesite.org/about_us/public_talks/

Galaxy Shapes in the Frontier Fields Observations

We can learn a lot about galaxies by analyzing their light, through computer modeling, and using other complex techniques. But at the most basic level, we can learn about galaxies by studying their shapes.

Galaxy appearance immediately reveals certain characteristics. Elliptical galaxies contain a wealth of old stars. Spiral galaxies are full of gas and dust. Distorted galaxies have likely experienced a gravitational interaction with another galaxy that warped their structure.

The Mice, as these colliding galaxies are called, are a pair of spiral galaxies seen about 160 million years after their closest encounter. Gravity has drawn stars and gas out of the galaxies into long tails.  Credit: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA

The Mice, as these distorted colliding galaxies are called, are a pair of spiral galaxies seen about 160 million years after their closest encounter. Gravity has drawn stars and gas out of the galaxies into long tails. Credit: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA

The Frontier Fields project adds another dimension to this simple analysis. When we look at extremely distant galaxies with the magnification of gravitational lensing, we see new detail that was previously obscured by distance. Their shapes are clues to what occurred within those galaxies when they were very young.

Galaxies viewed through the gravitational lenses of the Frontier Fields clusters can be seen at a resolution 10 times greater than non-lensed galaxies. That means those tiny red dots that so thrill astronomers in normal Hubble images actually have some structure in Frontier Fields imagery.

Previous studies, such as the Hubble Ultra Deep Field, The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, or even adaptive optics-enhanced studies by ground telescopes have shown that young, star-forming galaxies at about a redshift of 2 (existing when the universe was about 3.3 billion years old) appear to have a certain lumpiness. But without gravitational lensing, we lack the resolution to say for sure whether those lumps were massive clusters of newly forming stars, or whether some other factor was causing those galaxies to have a clumpy appearance.

Frontier Fields has revealed that yes, many of those galaxies have star-forming knots that really are quite large, implying that star formation occurred in a very different way in the early universe, perhaps involving greater quantities of gas in those young galaxies than previously expected.

Frontier Fields has also given us a better grasp of the physical size of gravitationally lensed young galaxies even farther away, at a redshift of 9 (when the universe was around 500 million years old). Observations show that these galaxies are actually quite small – perhaps 200 parsecs across, while a typical galaxy you see today is closer to 10,000 parsecs across. These observations help plan future observations with the Webb Space Telescope, picking out what will hopefully be the best targets for study.

This composite image shows examples of galaxies similar to our Milky Way at various stages of construction over a time span of 11 billion years. The galaxies are arranged according to time. Those on the left reside nearby; those at far right existed when the cosmos was about 2 billion years old. The Frontier Fields project is collecting galaxies from the earliest epochs of the universe to add to such comparisons. Credit: NASA, ESA, P. van Dokkum (Yale University), S. Patel (Leiden University), and the 3D-HST Team

This composite image shows examples of galaxies similar to our Milky Way at various stages of construction over a time span of 11 billion years. The galaxies are arranged according to time. Those on the left reside nearby; those at far right existed when the cosmos was about 2 billion years old. The Frontier Fields project is collecting galaxies from the earliest epochs of the universe to add to such comparisons. Credit: NASA, ESA, P. van Dokkum (Yale University), S. Patel (Leiden University), and the 3D-HST Team

Galaxy shape also plays a role in discoveries in the Frontier Fields’ six parallel fields, which are unaffected by gravitational lensing but provide a view into space almost as deep as Hubble’s famous Ultra Deep Field, with three times the area.

It’s well known that galaxies collide and interact, drawn to one another by gravity. Most galaxies in the universe are thought to have gone through the merger process in the early universe, but the importance of this process is an open question. The transitional period during which galaxies are interacting and merging is relatively short, making it difficult to capture. A distant galaxy may appear clumpy and distorted, but is its appearance due to a merger – or is it just a clumpy galaxy?

Collision-related features — such as tails of stars and gas drawn out into space by gravity, or shells around elliptical galaxies that occur when stars get locked into certain orbits – are excellent indicators of merging galaxies but are hard to detect in distant galaxies with ordinary observations. Frontier Fields’ parallel fields are providing astronomers with a collection of faraway galaxies with these collision-related features, allowing astronomers to learn more about how these mergers affected the galaxies we see today.

As time goes on and the cluster and parallel Frontier Fields are explored in depth by astronomers, we expect to to learn much more about how galaxy evolution and galaxy shapes intertwine. New results are on the way.

MACS J0416 Data is Complete

Observations of another Frontier Fields galaxy cluster and parallel field are complete. This time, we have new images for you of MACS J0416.1-2403. Here’s the galaxy cluster:

macs

And here is the parallel field:

 macs2

Beautiful, aren’t they? This is the second Frontier Fields cluster and parallel field to be fully imaged. You can see the first here.

Remember that to maximize scientific discovery, Hubble is using two of its instruments simultaneously to examine both the cluster and the parallel field, then observing the same areas again with the instruments switched.

Hubble takes two sets of observations, called epochs, in order to thoroughly examine the two areas. During the first, Hubble spent 80 orbits with the Advanced Camera for Surveys (ACS) pointing at the main galaxy cluster, and Wide Field Camera 3 (WFC3) looking at the parallel field. ACS provides a visible-light view, and WFC3 adds near-infrared light.

During the second epoch, Hubble spent 70 orbits targeting WFC3 on the main cluster and ACS on the parallel field.

Scientists are poring over the new data, and one result is already in. Expect to hear more about these observations in the near future.

Mapping Mass in a Frontier Fields Cluster

The Frontier Fields project’s examination of galaxy cluster MACS J0416.1-2403 has led to a precise map that shows both the amount and distribution of matter in the cluster. MACS J0416.1-2403 has 160 trillion times the mass of the Sun in an area over 650,000 light-years across.

The mass maps have a two-fold purpose: they identify the location of mass in the galaxy clusters, and by doing so make it easier to characterize lensed background galaxies.

Mass map of galaxy cluster MCS J0416.1–2403

The galaxy clusters under observation in Frontier Fields are so dense in mass that their gravity distorts and bends the light from the more-distant galaxies behind them, creating the magnifying effect known as gravitational lensing. Astronomers use the lensing effect to determine the location of concentrations of mass in the cluster, depicted here as a blue haze. Credit: ESA/Hubble, NASA, HST Frontier Fields

Astronomers use the distortions of light caused by mass concentrations to pinpoint the distribution of mass within the cluster, including invisible dark matter. Weakly lensed background galaxies, visible in the outskirts of the cluster where less mass accumulates, may be stretched into slightly more elliptical shapes or transformed into smears of light. Strongly lensed galaxies, visible in the inner core of the cluster where greater concentrations of mass occur, can appear as sweeping arcs or rings, or even appear multiple times throughout the image. And as a dual benefit, as the clusters’ mass maps improve, it becomes easier to identify which galaxies are strongly lensed, and which galaxies are farther away.

Stronger lensing produces greater distortions. Astronomers can work backwards from the distortions to pinpoint the greater concentrations of mass responsible for producing such altered images.

Stronger lensing produces greater distortions. Astronomers can work backwards from the distortions to pinpoint the greater concentrations of mass responsible for producing such altered images. Credit: A. Feild (STScI)

The depth of the Frontier Fields images allows astronomers to see extremely faint objects, including many more strongly lensed galaxies than seen in previous observations of the cluster. Hubble identified 51 new multiply imaged galaxies around this cluster, for instance, quadrupling the number found in previous surveys. Because the galaxies are multiples, that means almost 200 strongly lensed images appear in the new observations, allowing astronomers to produce a highly constrained map of the cluster’s mass, inclusive of both visible and dark matter.

The dark matter aspect is particularly intriguing. Because these types of Frontier Fields analyses create extremely precise maps of the locations of dark matter, they provide the potential for testing the nature of dark matter. Learning where dark matter concentrates in massive galaxy clusters can give clues to how it behaves and changes. And as the mass maps become more precise, astronomers are better able to determine the distance of the lensed galaxies.

In order to obtain a complete picture of MACS J0416.1-2403’s mass, astronomers will also need to include weak lensing measurements. Follow up observations will include further Frontier Fields imaging, as well as X-ray measurements of hot gas and spectroscopic redshifts to break down the total mass distribution into dark matter, gas, and stars.

Frontier Fields Finds Faint Light of Homeless Stars

The Frontier Fields’ project has detected the glow of about 200 billion freely drifting stars within the massive galaxy cluster Abell 2744. The stars were dragged from their home galaxies by gravitational tides during collisions and interactions over the course of 6 billion years.

As many as six Milky Way-sized galaxies were torn apart in the cluster. The light of the outcast stars is believed to contribute to 10 percent of the cluster’s brightness, though that light is quite faint because the density of the stars is low. The combination of depth and multiwavelength observations provided by the Frontier Fields program makes this study of such dim stars possible.

The total starlight of galaxy cluster Abell 2744 is depicted here in blue in this Frontier Fields image. Not all the starlight is contained within the galaxies, which appear as blue-white objects. A portion of the light comes from stars that have been pulled from their galaxies and now drift untethered within the cluster. Credit: NASA, ESA, M. Montes (IAC), and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

The stars are rich in heavy elements such as oxygen, carbon, and nitrogen, which means they formed from material released by earlier generations of stars. The presence of these elements indicates that the stars likely came from galaxies with similar mass and metallicity to our own Milky Way galaxy, which have the ability to sustain ongoing star formation and thus build populations of such chemically enriched stars. Elliptical galaxies are low in star formation while dwarf galaxies lack the kind of constant star formation that would be essential.

This discovery indicates that a significant fraction of the stars that would otherwise end up in these galaxies is being stripped out in the merger process. Astronomers intend to look for the light of such estranged stars in the remainder of the Frontier Fields galaxy clusters.

Frontier Fields Public Lecture

Want to hear about the Frontier Fields project straight from the scientist? On August 5, 2014, principal investigator Dr. Jennifer Lotz gave a public lecture entitled “The Frontier Fields: a Sneak Peek at the First Billion Years of the Universe” and the recorded webcast is available at the link below.

Dr. Jennifer Lotz
The Frontier Fields: a Sneak Peek at the First Billion Years of the Universe

August 5, 2014

How we far can we go? What are the faintest objects the Hubble Space Telescope can possibly see? Can we get a sneak peek at the early universe before the James Webb Space Telescope is launched? These are the key questions we hope to answer with the Frontier Fields campaign. Over this three year program, astronomers at the Space Telescope Science Institute will attempt to push the Hubble Space Telescope’s capabilities to its limits. This ambitious effort will combine the power of Hubble with the natural gravitational telescopes of massive clusters of galaxies that magnify more distant galaxies. Hubble will obtain the deepest ever optical and infrared images of six massive clusters, in parallel with the deep images of six neighboring “blank” fields. These observations will reveal galaxies about 10-20 times fainter than any previously seen, allowing astronomers to study the birth of galaxies like our own Milky Way.

https://webcast.stsci.edu/webcast/detail.xhtml?talkid=4287

This lecture is part of the monthly public lecture series at the Space Telescope Science Institute in Baltimore, Maryland. Each month addresses a different cosmic topic, usually related to Hubble, but always venturing to some fascinating part of the universe. For more information, check out the web page on HubbleSite:  http://hubblesite.org/about_us/public_talks/

 

Seeing Double (or More!) in Frontier Fields Images

The immense gravity in this foreground galaxy cluster, Abell 2744, warps space to brighten and magnify images of far-more-distant background galaxies as they looked over 12 billion years ago, not long after the big bang.  This is the first of the Frontier Fields to be imaged.

Galaxy cluster Abell 2744, the first of the Frontier Fields to be imaged.

Take a long look at this image. You’re seeing a lot of distant galaxies magnified by the natural “gravitational lens” of galaxy cluster Abell 2744. But you aren’t seeing as many as you think.

Gravitational lenses, natural magnifiers created in space when light is bent by the enormous mass of galaxy clusters, distort and enlarge the images of distant galaxies behind the cluster. But they do more than that: sometimes they replicate them, like multiple images in a funhouse mirror.

abell multiple

Galaxy cluster Abell 2744, with multiple images of individual galaxies marked. These multiple images are produced by the cluster’s gravitational lens.

In the above image, we’ve marked the galaxies that are actually images of the same galaxy by overlaying them with numbered triangles. Each galaxy has a number. The multiple images are identified by letters. The galaxies labeled 1a, 1b, and 1 c, for instance, are one galaxy, its image repeated three times. (Only numbers and letters are significant. The colors don’t represent anything, but are used to make it easier to distinguish the various numbered galaxies.)

In previous posts, we explained that mass distorts space. Light from a distant galaxy follows space’s curve like a ball rolling along a putting green. (Think of space as a miniature golf course with fewer animatronic dinosaurs.)

Sometimes, the level of distortion sends the light to multiple places. If you’ve ever seen a single candle reflected multiple times in the bottom of a wineglass, you’ve seen this distorting effect occur in lenses. In fact, gravitational lensing is so similar to glass lensing that you could replicate the distortions of a gravitational lens by grinding a glass lens to the same proportions and bumps.

And cosmic lenses are quite lumpy. The galaxies of the cluster, embedded in halos of dark matter, create bumps of mass. Light can take multiple paths around the galaxy cluster as it encounters the distortions in space-time created by the cluster’s mass. The closer the light of more-distant galaxies passes to the lens, the stronger the deflection. If the light passes close enough to the lens, these multiple images are likely to appear. The individual galaxies in the cluster also add small deflections, and occasionally help produce multiple paths for the light to reach us.

When astronomers look at a lensed image, they’re looking at a giant puzzle. They need to figure out where all the mass is in the image – most of it, being dark matter, is invisible. Pinpointing the multiple images of identical galaxies helps accomplish this because they’re a good indicator of how dramatically the light is being deflected.

Abell2744-multilens-1+markers Abell2744-multilens-3+markers

Some of the multiple images are obvious. Galaxy images 1a, 1b and 1c (left image) are good examples – they’re blue galaxies with red centers, and they look very like one another. The green-hued galaxy identified by 3a, 3b and 3c (right image) is another good example. Astronomers seek out those obvious candidates to start with, then try to build a model of how the mass in the cluster is distributed. Based on that model, they start identifying the multiple images that aren’t so obvious: Does this reddish galaxy to the side have a counterpart where the model says it should be? Analysis of attributes like color, and especially distance, also play an important role in determining which galaxies are multiples — a technique that comes in handy in many situations.

Thanks to reader Judy Schmidt for the idea for this post.

 

How Hubble Observations Are Scheduled

This is the third in a three-part series.

After observing time is awarded, the Institute creates a long-range plan. This plan ensures that the diverse collection of observations are scheduled as efficiently as possible. This task is complicated because the telescope cannot be pointed too close to bright objects like the Sun, the Moon, and the sunlit side of Earth. Adding to the difficulty, most astronomical targets can only be seen during certain months of the year; some instruments cannot operate in the high space-radiation areas of Hubble ’s orbit; and the instruments regularly need to be calibrated. These diverse constraints on observations make telescope scheduling a complex optimization problem that Institute staff are continually solving, revising, and improving.”

Preparing for an observation also involves selecting guide stars to stabilize.the telescope’s pointing and center the target in the instrument’s field of view. The selection is done automatically by the Institute’s computers, which choose two stars per pointing from a catalog of almost a billion stars. These guide stars will be precisely positioned within the telescope’s fine guidance sensors, ensuring that the target region and orientation of the sky is observed by the desired instrument.”]

A weekly, short-term schedule is created from the long-range plan. This schedule is translated into detailed instructions for both the telescope and its instruments to perform the observations and calibrations for the week. From this information, daily command loads are then sent from the Institute to NASA’s Goddard Space Flight Center to be uplinked to Hubble.

Hubble’s Flight Operations Team resides in the Space Telescope Operations Control Center at NASA’s Goddard Space Flight Center in Greenbelt, Md.  In addition to monitoring the health and safety of the telescope, they also send command loads to the spacecraft, monitor their execution, and arrange for transmission of science and engineering data to the ground.

Hubble’s Flight Operations Team resides in the Space Telescope Operations Control Center at NASA’s Goddard Space Flight Center in Greenbelt, Md. In addition to monitoring the health and safety of the telescope, they also send command loads to the spacecraft, monitor their execution, and arrange for transmission of science and engineering data to the ground.

The journey from proposal through selection and scheduling culminates in the email informing astronomers that their data is ready to be accessed. Usually, the process takes more than a year from idea to data—sometimes even longer. Of course, that’s when the real work begins—the analysis of the data and the hard work of uncovering another breakthrough Hubble discovery!