Physical properties of distant galaxies in VANDELS
We now know a fair amount about our own Milky Way galaxy, and several other galaxies that are relatively close to the Milky Way. However, there are still several open questions about galaxies that are further away from us. Studying distant galaxies also helps us understand how galaxies like our Milky Way formed, and what were the physical processes that shaped its evolution. Thanks to the deep VANDELS survey, we can now study in great detail the physical properties of galaxies almost 13 billion light years away from us (z ~ 6), when the universe was a tiny fraction of its current age.
Click on the image below to find out more about the VANDELS survey:
Discovery of the most distant radio galaxy to date
In June 2018, my research team discovered the most distant radio galaxy observed to date, named TGSS J1530+1049, at a distance of 12.7 billion light years away (redshift = 5.72)! In comparison, the age of the Universe is 13.6 billion years. Therefore, this is a galaxy that was formed within the first 7% of the Universe's lifetime! This discovery broke the distance record for a radio galaxy after almost 20 years. Radio galaxies are some of the most massive galaxies in the Universe and harbour a supermassive black hole in their centres that is actively eating up the gas and dust that surrounds it. Discovering such an object at such a large distance from us poses some interesting challenges about how and when the seeds of this galaxy and the supermassive black hole were sown, and how they evolved to be so massive in such a short period of time after the Big Bang.
The paper reporting this discovery has now been published in the Monthly Notices of the Royal Astronomical Society and can be found here:
Discovery of a radio galaxy at z = 5.72, 2018
In the media:
Astronomy Now: Most distant radio galaxy, host to a voracious black hole, is found
Phys.org: The most distant radio galaxy discovered
Astronomie.nl: Astronomen ontdekken verst verwijderde radiostelsel ooit (Astronomers discover the most distant radio galaxy ever)
BBC Brasil: Radiogaláxia mais distante da Terra é descoberta com participação de brasileiro - e dá mais pistas sobre o Big Bang (Most distant radio galaxy is discovered with Brazilian participation - and gives more clues about the Big Bang)
Media INAF: Scoperta la radiogalassia più lontana (The most distant radio galaxy discovered)
High-redshift extreme spectrum project (HiZESP)
We have started a large campaign to hunt for distant radio galaxies by taking advantage of the new all-sky surveys at low radio frequencies using telescopes such as the Giant Metrewave Radio Telescope (GMRT) in India, the Very Large Array (VLA) in USA and the Low Frequency Array (LOFAR) in the Netherlands and all of Europe. Early results from this project can be found here:
A search for faint high-redshift radio galaxy candidates at 150 MHz, 2018
In addition to studying these sources at radio wavelengths, it is essential to also observe them at optical and infrared wavelengths. As part of this project, we have been awarded observing time on telescopes all over the world to a) obtain spectra and determine redshifts of candidate high-redshift radio galaxies and b) observe our targets at near-infrared wavelengths to study the underlying stellar populations.
The telescopes being used for this project include the Hobby-Eberly Telescope (HET), Gemini North, William Herschel Telescope (WHT) and the Large Binocular Telescope (LBT) (Saxena et al. in preparation).
Modelling luminosities and sizes of radio sources across cosmic time
One of the first projects of my PhD was to build a model capable of tracking the evolution of radio galaxies from first principles, and predicting the luminosity and size distribution of radio sources at any given epoch. This model included recipes for a host of physical phenomenon and the results can be found here:
Modelling the luminosities and sizes of radio sources: radio luminosity function at z = 6, 2017