Back in 2013, Dr Vithal Tilvi was an integral member of the team led by Dr Steve Finkelstein of the University of Texas, Austin, in discovering the farthest known galaxy in the universe, estimated to be a staggering 13 billion light years away from Earth.
“Of course, it was a very exciting time being the first people in the world to discover and see the farthest galaxy in the universe. But I was even more excited being part of a collaborative team effort that contributes to generating new knowledge and advancing our understanding of the universe,” says the Goan astronomer, speaking to The Better India.
In astronomy, the unique thing is that by observing something really far away, we can also look back in time. Although light travels at a tremendous speed, the starlight, which carries information about this particular galaxy, reached Earth after traveling for 13 billion years. In other words, what we can see at present is actually a 13 billion year-old image of the galaxy. The importance of that discovery is the ability to see how the universe was in its infancy since we now know that it is about 13.8 billion years old.
To study this galaxy in detail, researchers employed the magnificent Hubble Space Telescope (HST) and other world class observatories on the ground. More than three years later in 2017, they discovered that this galaxy also contains a black hole at its centre.
There are many galaxies with such black holes (an extremely dense object in space from which nothing can escape, not even light) at their centres, but there was something particularly surprising about this one.
“For the creation of a black hole, a lot of material is required in a small place to generate a very strong gravitational force. But how come there was so much material available at a time when the universe was in its infancy? We need a lot of material like stars falling into the black hole or something that will generate extremely strong gravitational force,” recalls Dr Tilvi.
From discovering a black hole, last month Dr Tilvi went onto lead another NASA-sponsored project which discovered a group of galaxies called EGS77.
This group of three galaxies is even further away at approximately 13.1 billion light years away, and currently the farthest galaxy group known.
These discoveries seek to answer questions like how did the universe evolve from almost nothing to one that contains billions of stars, galaxies and planets? From nothingness, how did we get here? How many galaxies, planets and stars were there in the beginning? What was their chemical composition? Were there chemicals in the beginning of the universe that could have given rise to life like on Earth? Were those chemicals already present when the universe was born?
“We want to know how the universe evolved, how we came to this earth and what is our purpose. In fact, some of the chemicals including iron, carbon, that are found in our body can be made only in the interiors of stars. When stars explode in supernova, these chemicals are thrown onto planets, which eventually make it into our bodies. In essence, we are made of stuff that are inside stars,” he says.
Thus, understanding the cosmos is not merely a scientific endeavour, but stands at the heart of comprehending who we are and what our place is in this universe.
The Long & Winding Road
The discovery made in 2013 was a consequence of the largest HST project ever undertaken called the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), which was carried out between 2010 and 2013 by a team of international scientists, including those from NASA. Its objective was to capture the deepest image of the universe.
When you take the deepest image of the universe, you can also look really far away and capture images of the faintest galaxy, for which you need the telescopes like HST. If you use the HST, and take a picture for 15 minutes you can acquire very crisp images of galaxies. Since this telescope is in space, the clarity of the images is extremely good.
“To discover this particular galaxy, however, we had to use HST for one month straight. It was a bit like switching on your mobile phone camera and continuously clicking pictures for one month. The HST took all the images and we used them to conduct extensive data analysis. When we took the images from HST, we had identified about 200,000 galaxies. Out of those 200,000, we scooped out 10-20 best candidates that were really far from Earth. Out of those candidates, we discovered one galaxy that was the farthest,” he recalls.
One can imagine the effort it takes to find 1 out of 200,000 galaxies. This entire time-consuming process, from planning, execution to data analysis took seven years. As researchers, they don’t really know when a new discovery will happen. But the observations they noted in making this discovery will also prove invaluable to other scientists in finding answers to questions like how stars and planets were formed.
The Process and Execution
“There is a process we must follow for using the Hubble Space Telescope. We write a proposal which is sent to a selection committee managed by the Space Telescope Science Institute (STScl), which manages the Hubble Space Telescope. If the science is of very high quality, these proposals get accepted and then we get down to doing the project,” he says.
To execute this project, there are multiple procedural constraints. The HST is a very busy facility because that’s the telescope astronomers from all over the world want to use.
It is occupied most of the time, making the process of acquiring data a challenge on the telescope. Researchers also had to use other ground-based telescopes in the United States to assist with their research. In order to even get even one night’s worth of data on the HST, you have to go through a process that could extend up to a year. Add the years it requires to take observations and conduct data analysis, and it’s not hard to understand why this process takes so long.
Even following the discovery in 2013, it took nearly 3.5 years to get the requisite data and conduct analysis that discovered the candidate for the earliest black hole in the universe.
This galaxy is known by its location and has not been named yet. In astronomy, researchers cannot really give names to galaxies just discovered and there is a standard issued by the International Astronomical Union, where they identify any galaxy or a planet based on their coordinates. The position of every given place in the sky is predefined just like latitude and longitude. For objects in space, researchers use Right Ascension and Declination in place of latitude and longitude that we use on Earth.
The advantage of marking location instead of a name is to help researchers better locate that same galaxy anytime in the future. Since there are so many galaxies in the universe, giving them names would not suffice and create confusion.
Last month, a group of scientists including Dr Tilvi and a team from NASA discovered a group of three galaxies that were even further away than the one they found in 2013. They called this group EGS77 which is 13.1 billion years away, but this isn’t the most important facet of the discovery.
“As stated earlier, the universe back then was nothing like what we see today. It was entirely filled with what we call neutral hydrogen which acts like a fog and as a result light cannot travel freely. But we found that this group of galaxies is responsible for getting rid of this fog. As a consequence we now see the universe with much greater transparency. This is the most important result that came out of that discovery,” says Dr Tilvi.
“The young universe was filled with hydrogen atoms, which so attenuate ultraviolet light that they block our view of early galaxies,” said James Rhoads at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was part of the research team. “EGS77 is the first galaxy group caught in the act of clearing out this cosmic fog.”
“EGS77 was discovered as part of the Cosmic Deep And Wide Narrowband (Cosmic DAWN) survey, for which Rhoads serves as principal investigator. The team imaged a small area in the constellation Boötes using a custom-built filter on the National Optical Astronomy Observatory’s Extremely Wide-Field InfraRed Imager (NEWFIRM), which was attached to the 4-meter Mayall telescope at Kitt Peak National Observatory near Tucson, Arizona,” says NASA in a recent statement.
Once again, the research team had to spend three to four years just taking down the observations and another three years to conduct data analysis. This project was meant to discover galaxies that are very far and essentially right at the beginning of the universe.
“When you look at galaxies that are very far away, it is a challenge to discover them because of the hydrogen fog. On average it takes about two to three years to discover one galaxy that is this far despite using the best technology at your disposal. We had to spend about three-four years, including 60 nights on large ground-based telescopes,” says Dr Tilvi.
Once researchers obtain the data, they take very sensitive images of all galaxies in their purview and then the process of data analysis begins.
Like the 2013 discovery, their goal was to find how many of these galaxies are really far and identify the best candidates located very far away. To accurately measure the distance from Earth, they use special instruments called spectrographs.
For this project, researchers approached the W. M. Keck Observatory on Mauna Kea volcanic mountain in Hawaii perched above the clouds at 16,000 feet above sea level, which has some of the best spectrographs in the world. For this project, they used the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) on the Keck I telescope.
Coming back to the discovery itself, it’s clear that this could have been possible only in the last 10-20 years because of the available technology like the HST.
“The knowledge we are generating today will be used decades into the future as well. At a more fundamental level, however, this knowledge will advance humanity. These discoveries are a result of massive collaboration between scientists with remarkable levels of expertise from different parts of the world. It also requires incredible coordination and teamwork, working together for 5-6 years at a stretch. It’s like a short term marriage,” he recalls.
Curiosity & Research
For Dr Tilvi, who grew up in a remote village not very far from Panjim city in Goa, there wasn’t one particular moment which inspired him to work in astronomy. It was a gradual process. But it all began with the stunning night sky he regularly saw at home.
“My advantage was that I grew up in a village where I could see the clear sky filled with millions of illuminating stars. When I went to a city like Panjim, I could only see bright stars because of light pollution. People grow up in the city thinking that there are only these many stars, whereas I grew up in a place where I could see countless stars. My curiosity was naturally piqued by these sights and I would ask questions about how many stars are there in the sky, how far away they are from Earth, etc. You wouldn’t ask the same questions growing up in the city. In fact, you could see sights like the Andromeda Galaxy with the naked eye in my village,” he says.
This regular practice of looking at the night sky carried onto college, where he and his friends would stay overnight in remote corners of Goa with their small telescopes. Even during his Masters in Electronic Science, he would regularly engage in amateur astronomy-related activities like marathons to discover the largest number of faint objects in the sky, recognise the stars and planets, among other things.
But it never quite struck him that astronomy is where his passions lay and fortunately did not endure any external pressure to study medicine or engineering. The only thing he knew was his passion for research. Following his Masters, he worked for a few years at the National Institute of Oceanography in Dona Paula and National Antarctic Research Center in Vasco. Only then did he go to the United States for his PhD in astronomy and astrophysics.
After 15 years in the United States finishing his PhD in Astronomy at Arizona State University, Post doctoral at Texas A&M University and intensive research work, he came back to India late last year to join as a faculty at the State Higher Education Council of Goa.
The Council is recently set up to recommend Goa’s policy for higher education. Within the Council, he heads the Research Development Innovation Centre, and its primary goal is to raise the bar on research in all disciplines across various institutions in the state.
With his experience in working and conducting research in large facilities across the world and working with top experts from around the world, he thought that it’s time to use his expertise back home in India.
“See, there is no alternative to quality research. For higher education, we spend a lot of time on teachers and teaching methodologies. My experience in the States tells me that even if we hire the best teachers, without the requisite cutting-edge research we will not progress much. When a teacher goes to a class in India, he or she delivers textbook content that is more than 10 years old. Back in the States, the exact opposite happens,” he argues.
There the professor who teaches also engages in serious research, and their latest findings/content is immediately taught to students the next day, month or year. There is no large time lag in imparting knowledge produced by the latest research.
“If we do not conduct our own research and generate our own knowledge, India will not progress academically like it should. Our goal is to encourage faculty across all disciplines to do their own research starting with small projects,” he adds.
Despite coming back and looking to improve academic research in Goa, he continues to collaborate with astronomers in the United States, and conducts his own research.
After all, the pursuit of knowledge never stops, and sees no boundaries.
(Edited by Saiqua Sultan)