An extraordinary jet trailing behind a runaway pulsar is seen in this composite image that contains data from NASA's Chandra X-ray Observatory (purple), radio data from the Australia Compact Telescope Array (green), and optical data from the 2MASS survey (red, green, and blue). The pulsar - a spinning neutron star - and its tail are found in the lower right of this image (mouse over the image for a labeled version). The tail stretches for 37 light years , making it the longest jet ever seen from an object in the Milky Way galaxy, as described in our press release.
Lucia Pavan graduated with a master thesis in astronomy at the University of Padova (the same town from which Galileo discovered Jupiter's moons). Four years later she also got her PhD in Physics at the same university, working on "magnetars" -a particular kind of pulsars, with the highest magnetic fields. After the PhD, she obtained a postdoc position at the University of Geneva - Switzerland, working at the INTEGRAL Science Data Center (ISDC). In between, she moved to the US, working at University of Wisconsin-Madison for a few months. She currently lives in Geneva, working at the ISDC.
When I started to work on the sources discovered by the INTEGRAL satellite, I didn’t expect to find an object that was extraordinary not only for the properties of its emission, but also for its extension and shape in the sky. And yet this was the case when I came across IGR J11014-6103.
INTEGRAL is an ESA satellite in operation since 2002, sensitive mainly to X-ray and gamma-ray bands. The satellite has been accumulating data since the beginning of the mission, providing information on an always-growing number of X-ray emitters. It is thanks to this ability that new objects are continuously discovered. A large fraction of the sources that INTEGRAL has found still lacks any physical classification, a perfect area for new findings to be done.
Recently, a group at MIT's Kavli Institute held a contest called "The Art of Astrophysics". Just this week, they announced the winners. Here's an excerpt of an email from the organizers:
We are delighted to welcome guest blog posts from Peter Maksym from the University of Alabama and Davide Donato from NASA’s Goddard Space Flight Center (GSFC). These posts give more information about our new press release concerning evidence for a black hole ripping a star apart in a dwarf galaxy. Peter and Davide led two independent studies of this exciting find. We begin with Peter’s blog post.
In the middle of the twentieth century, an unusual star was spotted in the constellation of Canes Venatici (Latin for "hunting dogs"). Years later, astronomers determined that this object, dubbed AM Canum Venaticorum (or, AM CVn, for short), was, in fact, two stars. These stars revolve around each other every 18 minutes, and are predicted to generate gravitational waves - ripples in space-time predicted by Einstein.
When we released Chandra’s image of the pulsar known as PSR B1509-58 (or, B1509, for short), it received a lot of attention. It's a fascinating object. The pulsar at the center of the image is a rapidly spinning dense star that is spewing out energetic particles into beautiful structures spanning trillions of miles that glow in X-ray light. And, it looks like a giant hand. This fact helped trigger a whole host of other comments about this object found some 17,000 light years from Earth.
We'd like to welcome guest blogger Sebastian Heinz, Associate Professor in the Astronomy Department at the University of Wisconsin-Madison. He received his Ph.D. at the University of Colorado at Boulder. He studies relativistic jets -- a phenomenon observed around black holes and neutron stars, and began work on the project described here when he was a Chandra Postdoctoral Fellow at MIT.
Circinus X-1 had been a puzzle to X-ray astronomers almost from the moment of its discovery. It is an X-ray binary -- a neutron star sucking matter away from a companion star it is in orbit with, and it shines brightly when that matter spirals inward and eventually lands on the neutron star's surface. But it had defied classification into the basic categories scientists have been using for X-ray binaries. In some ways it behaves like a very young source, like the fact that the orbit of the two stars seems to change rapidly (and whenever things change rapidly in astronomy, we tend to infer that they cannot be very old). In other ways, it behaves like an old neutron star -- one that has lost most of the intense magnetic field which neutron stars are believed to be born with. It also blasts powerful streams of hot plasma, called jets, into interstellar space. And that's why I became interested. I study jets and I wanted to know why the jets from Circinus X-1 were able to light up and stay lit on scales of a few light years when other microquasar jets flared and then dimmed.
We are delighted to welcome a guest blog post from Zhiyuan Li, who led the work explained in our latest press release describing the best evidence yet for a jet from the supermassive black hole in our galaxy. Zhiyuan obtained his PhD at UMass/Amherst and did a postdoc at the Smithsonian Astrophysical Observatory. He went on to a Assistant Reseacher position at UCLA, where he worked with Prof. Mark Morris on the Sgr A* jet. He is currently a Professor of Astronomy at Nanjing University in China.
Today most astronomers believe that a supermassive black hole (SMBH), which weighs several million times more than the Sun, lurks at the very center of our Milky Way galaxy. The existence of such an entity was more just a speculation some 40 years back, when the two British astrophysicists, Donald Lynden-Bell and Martin Rees, first proposed the idea. Lynden-Bell and Rees suggested one particular observational test: "Very long baseline interferometry may soon be possible…to determine the size of any central black hole that there may be in our Galaxy" -- and they were right. There soon came the memorable discovery by Bruce Balick and Robert Brown, who in early 1974 used the Green Bank interferometer to find a compact radio source at the expected position. The source is now widely known as Sagittarius A* (Sgr A*) and accepted as the radio counterpart of the putative SMBH. (Most astronomers would use Sgr A* to denote the SMBH, and we do so below.)
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