[Koji's blog] An “X-ray Astronomer” Among Radio Telescopes

To me, an observational astronomer, there is no such thing as X-ray astronomy. What I do is astronomical research on objects that happen to emit X-rays, as well as ultraviolet, visible, and infrared, etc. light. My research interest is not X-rays, but astronomical objects called cataclysmic variables and symbiotic stars – both involve dense “ash” of sun-like stars called white dwarfs in binary systems.

Having said that, to instrument builders, X-ray astronomy *is* a distinct discipline. Also, it takes time to become adept at using any complex tools and X-ray data analysis is no exception. In that sense, in terms of technical proficiency, I am an X-ray astronomer. I have also worked with infrared, visible light, and ultraviolet observations before – but not radio observations, not even by collaborating with the experts, until recently.

This is changing, partly because a phenomenon I’m very interested in called “nova outburst” can produce radio waves and X-ray photons. Basically, novae are nuclear explosions on the surface of the white dwarfs in cataclysmic variables and symbiotic stars. The material ejected (called ejecta) from these explosions emit radio waves when they are just expanding. However, collisions within the ejecta or collisions of the ejecta with some other materials can heat them up to many millions of degrees, making them bright in X-rays. So it makes a lot of sense to observe novae with X-rays and radio at the same time. Another reason for my evolving collaboration is that the premier instrument of radio astronomy has undergone a significant upgrade in the last several years, making them capable of doing observations that were never possible before.

Recently, I had the chance to visit the Science Operations Center of National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. About one hour west, on the high plains of San Augustin, is what used to be called the Very Large Array (VLA). The VLA uses a set of 27 antennas, each having a diameter of 25 meters (or 82 feet). By combining the signals from these antennas, the VLA acts like a much bigger telescope – the separations of the antennas, not the size of each individual antenna, determine how detailed an image we get (“the angular resolution”). The antennas of the VLA can be moved along special railroad tracks to several pre-constructed stations to suit the need of the observers. It’s a stunning sight to see the VLA, particularly when the entire array is moving from one target on the sky to the next. I even got to climb up on the 28th antenna undergoing routine maintenance (you don’t want to do that with ones in use – for one thing, if the antenna is tilted to observe an object low in the sky, it would be very dangerous).

Credit: Koji Mukai

Credit: Koji Mukai

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[Sara's blog] Be a scientist!

In one of last week’s contests, we asked our readers/followers/listeners (whatever you guys are – we love you!) to tell us about the things they’d like to see covered here on Blueshift.  And we got tons of interesting ideas that’ll fuel a bunch of our weekly brainstorming sessions!  One of the suggested topics that came up more than once was what we often call “citizen science,” or opportunities for anyone, anywhere to get involved with a big scientific effort.

Image credit: James Chao

Over a decade ago, I remember using SETI@home as my screensaver. I ran their software and donated my computing power (and my university’s bandwidth) to analyze radio data for signs of extraterrestrial life. I’d come back to my computer and watch the data being crunched (it was often more interesting than whatever I was about to use the computer for), wondering if something unusual would be found. I felt connected, even involved, in this scientific effort. SETI@home is on the edges of citizen science, as it’s more about harnessing computer power than human power. Citizen science is all about the citizens!

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[Sara's blog] Why?

Today’s episode focuses on a surprising result found by a NASA balloon-borne experiment. We chose this story because it highlights the excitement and uncertainty in any scientific experiment – you never know what you’ll find. Will your data support your predictions, contradict them, or point you in an entirely new direction? ARCADE was launched to look for the radio signals of the first stars in the Universe, but their detector found a strange, strong signal coming from deep space. What is it? Good question.

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[podcast] Confounding Cosmic Questions

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This episode features a strange signal from deep space, which could be a plot straight out of a Hollywood film. But this radio signal was detected by a NASA mission called ARCADE, which flew above the atmosphere suspected from a balloon to capture light from the first stars and galaxies that formed in the Universe. When data showed something totally unexpected, that’s when things got interesting.

We interviewed Al Kogut and Dale Fixsen about this discovery, ARCADE, and how you can also detect this mysterious radio signal from outer space with any FM radio.

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