Astronomers are eternal scholars, but nature is a strict professor

28 Jun 2018

Dr Masha Chernyakova, a lecturer in astrophysics at Dublin City University. Image: DCU

Dr Masha Chernyakova, a lecturer in astrophysics at DCU, writes about the realities of understanding the cosmos and solving the mysteries of gamma-ray binaries.

From the outside, it can seem somewhat overwhelming to think of all the unanswered questions in the universe, but one of those looking to find them is Dr Masha Chernyakova of Dublin City University (DCU).

After receiving her bachelor’s and finishing her master’s degree from the Moscow Institute of Physics and Technology in 1995, Chernyakova went on to receive a PhD in physics from the Lebedev Physical Institute.

After some postdoctoral work at the Integral Science Data Centre in Geneva, Switzerland, and at the Dublin Institute of Advanced Studies, she took up an academic position in the School of Physical Sciences at DCU in 2011.

She is currently a lecturer in astrophysics, chair of physics with the astronomy programme board and a member of the DCU centre of astronomy and relativity, C-fAR.

What inspired you to become a researcher?

When I was a student, I would have regularly visited different scientific laboratories in the Space Research Institute and I was deeply impressed by the research done in the High-Energy Astrophysics group led by Prof Rashid Sunyaev.

We were told that you need information about the distant worlds to learn about most energetic processes in the universe and we were shown the amazing data from the Granat mission.

I was lucky to get a chance to do a master’s project in this group and I’m still amazed by the surprises that new observations bring us.

Can you tell us about the research you’re currently working on?

For a long time, I have been very interested in the high-energy emission coming from the binary systems – systems in which a compact source (neutron star or black hole) is orbiting around a hot, young, massive optical star.

Such stars are known to constantly lose their mass in the form of stellar winds, releasing the energy as x-rays. Actually, more than half of the galactic x-ray sources are accreting binaries, but only a few are binary systems called gamma-ray binaries.

I was always very puzzled as to what makes these binaries so special, but most of these gamma-ray binaries are so compact that the source is always hidden from us by the material ejected from the massive companion, except for two.

The source of these was revealed as a radio pulsar, rapidly rotating neutron stars ejecting a beam of highly relativistic electrons and positrons. The collision of this relativistic wind with the wind of the massive star forms a shock wave, which can lead to the very effective particle acceleration, producing very high-energy emission.

During my PhD, I studied the origin of the x-ray emission from one of these systems – PSR B1259-63 – and this system was the first binary system from which the High-Energy Stereoscopic System (HESS) found very high-energy emissions in 2004.

Despite many multi-wavelength campaigns, we have managed to understand what is going on in this system, yet it still brings us lots of surprises. And we are sure in the nature of the compact source in this system!

In our group, we keep an eye on all known gamma-ray binaries, organise multi-wavelength observations and do theoretical modelling, trying to reveal the secret of extreme acceleration in these systems.

How do you conduct your research?

Space research has proven to be very stimulating for new technologies. New observations always bring new questions to answers – this requires more and more sensitive telescopes.

Stereoscopic Cherenkov telescopes such as HESS, VERITAS and MAGIC proved to be very powerful and opened up a whole new domain in astrophysics. But, in my research, I constantly find out that even better sensitivity is needed to understand the observations in an unambiguous way.

The Cherenkov Telescope Array (CTA) is a new observatory with more than 100 telescopes in northern and southern hemispheres, and should start its operations in about five years’ time. Its sensitivity will be 10 times better than is currently available, and the results should be really groundbreaking.

Irish scientists are members of CTA and, in my work, I simulate CTA observations of various sources in order to define the best observational strategy.

What are some of the biggest challenges you face as a researcher in your field?

There are two sides to this question. One is purely scientific: we need better instruments and larger statistics to answer hot questions.

The other one is related to funding, as you need money to build new instruments as well as to create a team, hire postdocs and postgraduates. Unfortunately, in Ireland, securing funding for fundamental research is currently very problematic.

Are there any common misconceptions about this area of research? How would you address them?

Contrary to popular belief, the work of astronomers nowadays is not sitting all night long staring into the telescope. Even using the optical telescope, you see the results of your observations on the computer and your presence for the observations is needed only for a double-check that all is going fine.

X-ray and gamma-ray observations are done with the space-borne observatories and in this case, observations can be performed at any time of the day and night.

When you want to understand the nature of any source in the sky, you need to use all the available information at very different energy ranges, starting from radio and up to very high energies. Also, many sources are variable on very different time scales, and you have to take it into account in your modelling.

Now, scientists are able to observe the life of sky objects in a very detailed way, and you need computer modelling in order to be able to interpret what you see.

In their everyday life, astronomers actually act as eternal scholars, solving tasks which nature, a very strict professor, set them.