4 minute read
UWC Future Researchers | Third Edition
DR. FANXIA AN
Could you give a brief explanation of what the COSMOS field is?
The COSMOS field is an astronomical survey field, located near the equator in the sky. The location made it accessible to several ground-based large telescopes in the Northern and Southern Hemispheres, as well as the major space-based telescopes. Consequently, it is one of the best-studied fields, which yielded a rich trove of astronomical data. Therefore, it is ideal to study the properties of the galaxies in our universe.
What is the importance of the Meerkat radio telescope?
The MeerKAT radio telescope is currently themost sensitive radio telescope in the SouthernHemisphere. The MeerKAT radio is set to besurpassed by the Square Kilometre Array (SKA),which will be the world’s largest radio telescopewhen complete. It will have unprecedentedpower in reaching deeper space and formingclearer images, which will help us explore theorigins of our Universe and our home galaxy —the Milky Way, to better understand our ownposition in the Universe.
How were your findings conducted?
We used the early science data observed by theSouth African MeerKAT telescope to analysea little more than 2000 galaxies. Galaxies area fundamental component of our Universe,and understanding how they form and evolveover cosmic time remains one of the greatestchallenges of modern astronomy. We selected2,094 galaxies that are active in forming stars,which means they are energetic and young(in cosmic time scales). This is an ideal samplefor us to study the growth of the galaxies andthe key features that affect their formation andevolution. The distances to these galaxies areso great that light, the fastest messenger inthe Universe, takes roughly 1 to 11 giga-years(Gyr=
9 years) to arrive from them. In this way,the galaxies we observe now reflect how theyused to be roughly 1 to 11 billion years ago.That means we have a collection of galaxies atdifferent evolutionary stages.
We then studied the fundamental physicalproperties of these distant galaxies by combiningthe new observations from MeerKAT and theexisting observational data from other telescopes— remember that this is one of the best-coveredsurvey fields. The MeerKAT data was collectedover nearly 20 hours as part of the MeerKATInternational GHz Tiered Extragalactic Exploration(MIGHTEE) project, one of the MeerKAT’s largesurvey projects prioritised by the South AfricanRadio Astronomy Observatory (SARAO).
By combining the emission of light, from thesegalaxies, we measure how massive, how active,and how bright they appear to be at differentradio frequencies, as well as other fundamentalphysical properties. We then connect theintensities of radio emission with the measuredphysical properties of these galaxies.
What was the most challenging part of your research?
Combining different data from differentwavelengths (optical, infra-red, and radio) is themost challenging part of our work. The angular
resolutions of these observations differ by aboutten times. It means that a source of emission wesee in the radio data might correspond to severaldifferent galaxies that are detected at optical orinfra-red. Therefore, we must be careful when wecombine different kinds of observations to fullyutilise the multi-wavelength data richness of thefield.
Did COVID-19 have an impact on your research?
Yes. It was very hard to discuss the details withmy colleagues effectively when we were unableto meet face-to-face.
Was your research impacted negatively or positively as you collaborated with many others from the international community?
International collaboration is definitely a positive.
What impact do you believe the MIGHTEE (MeerKAT International GHz Tiered Extragalactic) programme could have in the future of South African astrophysics research?
I’d like to comment on the MeerKAT project ingeneral. On the one hand, as a precursor to theSKA (Square Kilometre Array), which is a largeinternational collaborative project, MeerKAT willenhance the international collaboration betweenastronomers in South Africa and other countries. It issomething that draws ideas, talents, and resourcesinto South Africa. On the other hand, South Africanstudents will have more opportunities to becomeactively involved in international research projects.They may be supervised by senior researchers ofinternational standing.
Therefore, we can expect astrophysics research in South Africa to flourish over the coming decades.
Do you believe that the MIGHTEE programme can benefit the general public here on earth and if so, how?
Certainly. It is no secret that MeerKAT-related projects are benefiting local communities and the public, by providing more jobs, more investment, and educational opportunities. The latter is especially of long-term value. The local communities are key stakeholders in the SKA(Square Kilometre Array) projects, and I believe that on a deeper level the relation is more mutual than one would imagine. The large projects are not simply there to hand out something to the communities.
The reality is that people from all over the worldcome here to learn from these communities anddraw inspiration from them, too. I believe that intime the SKA (Square Kilometre Array) projectswill be a venue where the communities’ voicesand expressions can be heard internationally.
Could you briefly explain the astronomy data science products you and others used and what impact they had on the programme?
I’d like to focus on the MeerKAT data we used in our project. Radio signals at the frequency of1.3GHz, where the MeerKAT is very sensitive, are dominated by a type of radio emission called, ‘The Synchrotron Radiation.’ These emissions come mainly from the supernovae in galaxies, which represents the number of large stars exploding (i.e. dying) at the moment. This information is key to understanding the evolutional stages of the galaxies.
Who or what inspired you to become an astrophysicist?
My high-school physics teacher in China inspiredme.
Do you believe the future looks bright for future astronomists in South Africa?
Definitely. South Africa is a young country with many bright young minds. She has the backing of the international research community. She holds the land to which these people have a special and deep tie.
