The Discovery of Particle Re-acceleration in a Galaxy Cluster Collision

Felipe Andrade-Santos and Reinout van Weeren
Felipe Andrade-Santos and Reinout van Weeren

For this guest blog post, we are lucky to have not one, but two, contributors. Reinout van Weeren obtained his PhD from Leiden University, The Netherlands, before moving to the Harvard-Smithsonian Center of Astrophysics as an Einstein Postdoctoral Research Fellow. He is currently a Clay Fellow at the same place. He works on merging galaxy clusters, focusing on combined radio and X-ray observations. Felipe Andrade-Santos obtained his PhD from the Universidade de São Paulo, Brazil, before becoming a postdoctoral research fellow at the Harvard-Smithsonian Center of Astrophysics. He works on X-ray observations of galaxy clusters and galaxy cluster samples. Reinout and Felipe recently presented their study on the merging galaxy cluster system Abell 3411 and 3412 at the 229th meeting of the American Astronomical Society meeting in January 2017.

Galaxy clusters are the most massive objects in the Universe bound together by gravity and contain up to a few thousand galaxies. They are also permeated by very thin 100-million-degree gas that is held together by the cluster's strong gravitational pull. This hot gas can be imaged with X-ray satellites such as NASA's Chandra X-ray Observatory. Galaxy clusters form by mergers of smaller clusters and galaxy groups. During a merger event, which typically lasts for about a billion years, the galaxies mostly fly past each other without strongly interacting. In contrast, the diffuse gas in the merging clusters collides, creating giant shock waves, which are cosmic versions of sonic booms generated by supersonic aircraft. Cluster mergers have been of great interest to astronomers and us because of the extreme physical processes that take place during such events.

Radio telescopes have shown that large regions of merging galaxy clusters glow at radio wavelengths. The radio emission is produced by tiny particles, called electrons, which spiral around magnetic field lines and have energies that are a million times higher than the particles making up the hot cluster gas. Astronomers have long been puzzled by how these energetic electrons are produced. One idea is that the energetic particles are accelerated to these extreme energies by shocks created when clusters collide and merge.

NGC 6357: Cosmic 'Winter' Wonderland

NGC 6357

Although there are no seasons in space, this cosmic vista invokes thoughts of a frosty winter landscape. It is, in fact, a region called NGC 6357 where radiation from hot, young stars is energizing the cooler gas in the cloud that surrounds them.

This composite image contains X-ray data from NASA's Chandra X-ray Observatory and the ROSAT telescope (purple), infrared data from NASA's Spitzer Space Telescope (orange), and optical data from the SuperCosmos Sky Survey (blue) made by the United Kingdom Infrared Telescope.

Chandra’s Arcand Wins Smithsonian Education Award

Smithsonian Education Award
SI Secretary Skorton, Kim Arcand, Patricia Bartlett, Roger Brissenden (Credit: Smithsonian)

Many people associate the Smithsonian Institution with a handful of museums on the National Mall in Washington, D.C., when, in fact, the Smithsonian consists of 19 museums, 9 research centers, a zoo, and affiliates around the world.

One fact that may not be known to some is that NASA’s Chandra X-ray Observatory is inextricably linked with the Smithsonian. The Smithsonian Astrophysical Observatory (SAO) in Cambridge, Mass., was at the center of the conception and development of the telescope and today it controls Chandra’s science and flight operations. In other words, Chandra is both a NASA and a Smithsonian mission.

Kim Arcand (Credit: Smithsonian)

One of the core tenants of the Smithsonian’s mission is the “increase and diffusion of knowledge.” This means that education and outreach can often take center stage at the Smithsonian. To highlight the important role education plays, the Smithsonian gives out one award every year to an employee that recognizes “creativity, excellence, and commitment to serving the nation through educational programming, exhibits, publications, and digital media.”

We are thrilled to announce that this year’s winner for the 2016 Smithsonian Education Achievement Award is Chandra’s visualization lead, Kimberly Arcand. Arcand was presented with the award on December 8, 2016 at the Smithsonian Castle in Washington, D.C. Among the Chandra-led projects being recognized were the NASA-funded public science programs "From Earth to the Universe" "Here, There & Everywhere," and “Light: Beyond the Bulb,” as well as Chandra community programs for girls and boys to improve coding skills with NASA data, and cutting-edge Chandra data visualization projects such as data-based 3D printed supernova remnants.

Super Starburst Galaxy Found One Billion Years After the Big Bang

Jingzhe Ma
Jingzhe Ma

We are pleased to welcome Jingzhe Ma as a guest blogger. She is the first author of a paper that is the subject of our latest press release. Jingzhe is a PhD candidate at the University of Florida, working with Prof. Anthony Gonzalez and Prof. Jian Ge. She is going to defend her PhD dissertation next summer. She has been working on the formation and evolution of high-redshift dusty galaxies through multi-wavelength observations. She joined the South Pole Telescope Sub-Millimeter Galaxy (SPT SMG) Collaboration led by Prof. Joaquin Vieira in 2012.

When Prof. Anthony Gonzalez first introduced me to the SPT SMG group, I was fascinated by the sub-millimeter galaxies discovered by the South Pole Telescope, which is located at the geographic South Pole. We call them sub-millimeter galaxies because these galaxies were historically first discovered at sub-millimeter wavelengths (slightly shorter than one millimeter). They are bright at these wavelengths but very faint in the visible wavelengths due to the large amount of dust in these galaxies. Dust plays an important role, by absorbing and scattering the ultraviolet and visible light from newborn stars. The dust gets heated and re-radiates light in the infrared. I was interested in further studying these objects not only because these galaxies are forming stars at tremendous rates and have revolutionized our understanding of galaxy evolution, but also because these galaxies are magnified by massive foreground galaxies, which act as a gravitational lens. “Wearing” a gravitational lens, we are able to see better.

Women in the High Energy Universe: Karla Guardado

Karla Guardado
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.

Cygnus X-3 and Its Little Friend

Michael McCollough
Michael McCollough

We are pleased to welcome Dr. Michael McCollough as our guest blogger. Dr. McCollough is the first author of a paper that is the subject of our latest press release. He has spent the last 30 years working with and analyzing data from astronomical radio, optical, X-ray, and gamma-ray telescopes. Currently, he serves as an Archival Astrophysicist at the Chandra X-ray Center in Cambridge, Mass.

Throughout my career I have been a multi-wavelength astronomer. To fully understand astronomical objects, one must look across the electromagnetic spectrum (from radio waves to gamma-rays). Also throughout my career I have been doing spacecraft operations. Starting with NASA’s Hubble Space Telescope (before, during, and after launch), ROSAT, NASA’s Compton Gamma-Ray Observations with the Burst and Transient Source Experiment (BATSE), and currently with NASA’s Chandra X-Ray Observatory. It was when I was working with BATSE that I was introduced to Cygnus X-3. Discovering that high-energy X-rays (as seen by BATSE) were correlated with emissions in the radio.

Starvation Diet for Black Hole Dims Brilliant Galaxy

Markarian 1018
Astronomers may have solved the mystery of the peculiar volatile behavior of a supermassive black hole at the center of a galaxy. Combined data from NASA's Chandra X-ray Observatory and other observatories suggest that the black hole is no longer being fed enough fuel to make its surroundings shine brightly.

Monster Flares in Otherwise Ordinary Extragalactic X-ray Binaries'

Jimmy Irwin
Jimmy Irwin

We are pleased to welcome Jimmy Irwin as our guest blogger today. Jimmy is the first author of a new Nature paper describing the detection of two mysterious, flaring X-ray sources in Chandra data. Irwin is an associate professor at the University of Alabama. After obtaining his PhD from the University of Virginia, he was a postdoc, a Chandra Fellow, and a research scientist at the University of Michigan. He studies the X-ray binary and hot gas content of galaxies, as well as the hot intracluster medium of groups and clusters of galaxies.

Projects don't always turn out the way one expects them to. Sometimes the result is uninteresting, but other times they far exceed expectations. Our project began as an undergraduate endeavor for two students looking to work on a project for college credit. A third student, who was a friend of one of the students, joined the project just for fun.

X-ray Telescopes Find Evidence for Wandering Black Hole

Astronomers have used NASA's Chandra X-ray Observatory and ESA's XMM-Newton X-ray observatory to discover an extremely luminous, variable X-ray source located outside the center of its parent galaxy. This peculiar object could be a wandering black hole that came from a small galaxy falling into a larger one.

Astronomers think that supermassive black holes, with some 100,000 to 10 billion times the Sun's mass, are in the centers of most galaxies. There is also evidence for the existence of so-called intermediate mass black holes, which have lower masses ranging between about 100 and 100,000 times that of the Sun.


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