hello, vela

Things have shifted dramatically since I have completed my first year here at Clemson University. Just a few notes on the past year:

I survived!
I currently have a 3.6 GPA.
I have begun research with Dr. Marco Ajello, a high energy astrophysicist in the department (View his page here.)

It has been a whirlwind of emotions, stress, and excitement. I have one more year of full time coursework before tackling the qualifier exam next August. After the qualifier, I will be free to dedicate my time to PhD research full time. 

In January, I added a little bit more to my workload. In addition to being a TA (teaching introductory astronomy labs), classwork, and operating the planetarium, I got involved in a new research project with Dr. Ajello. 

It’s been quite an exciting endeavor. In summary, Dr. Ajello discovered 5 new Galactic sources in the gamma rays with the FERMI-LAT satellite. These sources have a very hard gamma ray photon index and all lie along the Galactic plane of our galaxy, the Milky Way. The locations of the sources along the Galactic plane and their extreme gamma ray spectra suggests that these objects are close. And by close, I mean, in the Milky Way, in our Galactic neighborhood. 

I have been focused on one peculiar source that Fermi detected. I got involved with it as soon as the XMM-Newton X-ray satellite observed the gamma ray source in the X-rays. So not only have we observed this object in the gamma rays, but we now have a new piece of information: what it looks in the X-rays (in the energy range of 0.3keV-10keV). We found diffuse, soft x-ray emission surrounding the Fermi position of the source. In fact, it looks a lot like a shock (see photo below). 


XMM-Newton data of Fermi source. Shock-like in appearance. Soft, diffuse x-ray emission present.
to After some research, my supervisor (Marco Ajello) and a postdoc (Stefano Marchesi) felt confident in the associated region: The Vela supernova remnant (SNR). 

The Vela SNR resides in the constellation Vela. It is more of a southern constellation. It probably never fully rises here in Clemson but is just southwest of the constellation Canis Major. The Vela SNR is what is left of a massive star that exploded about 11,000 years ago just 290 pc from Earth. 290 parsecs is nearly 1,000 light years or nearly 63 million astronomical units from Earth, which is 63 million times farther from us than we are from the Sun. Does that sound like a large distance? Yes? Well it’s because it is! An even more astonishing truth about this distance is that the Vela SNR is actually the closest composite SNR to Earth, making it a fascinating research tool for learning the basics about SNRs. 

Typically, a star 4 to 10 times the mass of the Sun will end its life in a massive explosion, known as a supernova. In extreme cases the star collapses in on itself to form a black hole, but in other cases, the star leaves behind a rapidly rotating neutron star. The neutron star is what is left after the core collapse of a star, the collapse creates pressures so great, the protons and electrons in the core of the star combine together to form neutrons, hence the term neutron star. The star is left rapidly rotating, as the explosion ejects large amounts of material into its surroundings, forcing the star’s angular momentum to dramatically increase. Neutron stars also have an intense magnetic field that often becomes distorted by the intensity of the star’s angular momentum, extending itself in a long beam from both poles. Charged particles leaving the surface of the neutron star travel along the magnetic field lines along the long beam as the star rotates, creating a beam of light along the magnetic field lines. As the star rotates, the beam of light shines towards Earth much the same way a lighthouse beams a light as it rotates. This creates light pulses that can be detected from Earth. In this case, neutron stars are also called pulsars for their detected light pulses. For the Vela SNR, there lies a pulsar in the center of the remnant and is pictured in the image below. 


Optical image of the Vela SNR from the Anglo-Australian Observatory’s UK Schmidt Telescope showing gorgeous detail of the supernova remnant.. The red box indicates where the pulsar sits.
The cloud like structures in this image represent the supernova explosion shell as it moves into the interstellar medium. They are optical filaments representing the front shock of the explosion as it interacts with the surrounding. Our shock is also visible in this image but we will get to that 😉

So our shock has something to do with the SNR, but which part? SNRs can be complex in structure and in their spectral properties, ranging from radio to gamma ray emission. Looking at our x-ray source in many ranges of the electromagnetic spectrum can provide several clues to its properties and maybe even its origin.  Below is an optical image from the Anglo-Australian Observatory’s UK Schmidt Telescope that shows gorgeous detail of the supernova remnant. 

This summer I have dedicated my time to researching this region, finding out the complexities of the Vela SNR and the immediate area of our shock. It has been an amazing experience getting to do astrophysics research. It’s exactly how I imagined… Absolutely breath taking and humbling! Hopefully the paper for our x-ray source will be published by Christmas time. If this intrigues you in the slightest I hope you stay tuned for all the intriguing details! 

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