At the Brink of a Discovery, Indian Scientists Hope to Trace the First Signals from Stars & Galaxies!

A team of Indian astrophysicists is searching for signals from the first stars and galaxies that can answer many questions about the ‘dark ages’ proceeding the Big Bang.

The 12-member team of researchers from Raman Research Institute (RRI), Bengaluru, is using an indigenous radio telescope and other instruments in its attempt to trace these signals.

The Atacama Pathfinder Experiment (APEX) telescope looks skyward during a bright, moonlit night on Chajnantor, one of the highest and driest observatory sites in the world. Astronomical treasures fill the sky above the telescope, a testament to the excellent conditions offered by this site in Chile’s Atacama region. On the left shine the stars that make up the tail of the constellation of Scorpius (The Scorpion). The scorpion’s “stinger” is represented by the two bright stars that are particularly close to each other. Reaching across the sky and looking like a band of faint, glowing clouds is the plane of the Milky Way. Between Scorpius and the next constellation to the right, Sagittarius (The Archer), which looms over APEX’s dish, a sparkling cluster of stars can be clearly seen. This is the open cluster Messier 7, also known as Ptolemy’s Cluster. Below Messier 7 and slightly to the right is the Butterfly Cluster, Messier 6. Further to the right, just above the edge of APEX’s dish, is a faint cloud which looks like a bright smudge. This is the famous Lagoon Nebula (see eso0936 for a closer view). With a primary dish diameter of 12 metres, APEX is the largest single-dish submillimetre-wavelength telescope operating in the southern hemisphere. As the telescope’s name suggests, it is blazing a trail for the biggest submillimetre observatory in the world, the Atacama Large Millimeter/submillimeter Array (ALMA), which will be completed in 2013 (eso1137). APEX will share space with the 66 antennas of ALMA on the 5000-metre-high Chajnantor plateau in Chile. The APEX telescope is based on a prototype antenna constructed for the ALMA project, and it will find many targets that ALMA will be able to study in great detail. ESO Photo Ambassador Babak Tafreshi made this panorama using a telephoto lens. Babak is also the founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a nighttime backdrop of stars, planets and celestial events. More information APEX is a collaboration between the Max-Planck-Institut für Radioastronomie (MPIfR), the Onsala Space Observatory (OSO), and ESO, with operations of the telescope entrusted to ESO. ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. Links Information about APEX ESO Photo Ambassadors   #L

Image for representation only. Source: by By ESO/B. Tafreshi, via Wikimedia Commons

The team has claimed that it will soon be possible to detect such signals, based on the first round of observations from a place located 4,800 metres above sea level, in Ladakh. According to a report by The Times of India, it is the highest night sky observation point in the world.

The project is named SARAS (Shaped Antenna measurement of the background Radio Spectrum). It consists of an antenna connected with analogue as well as digital receivers that capture data from the sky and record it for further analysis. The team aspires to detect the signals emitted when the first stars and galaxies were formed. It is believed that these signals, known as the 21-cm signals, hold the key to many unanswered questions.

Being emitted an entire epoch ago, the signals are extremely weak to catch. They are believed to have been emitted when the universe was only 250-550 million years old. (It is now 13.7 billion years old.)

“The frequency range one needs to look for the signal is between 40 MHz and 200 MHz. Contaminations can be a million times stronger than the signal. Hence, it comes as no surprise that after more than a decade of international efforts, the signal has not yet been detected…After acquiring data for four nights in the Ladakh region, we are analysing it. The primary results are encouraging and we are achieving amazing levels in sensitivity. This has boosted our confidence that detection of the signal may not be too far,” team member Saurabh Singh told TOI.


The signal data will be shared with Prof Rennan Barkana, an expert from Tel Aviv, Israel.

Also read: Indian-American Scientist Wins Breakthrough Foundation Prize, Also Called ‘Oscars of Science

What were the dark ages?

It took approximately 400,000 years after the Big Bang for the universe to cool down enough for ions to recombine into atoms and create light. This period is referred to as the ‘dark ages’. The signals that were emitted from the stars and galaxies in this period are precious to expand our understanding of the dark ages.

Scientists have been trying to trace these signals for many years now. A telescope project titled Square Kilometre Array (SKA) has been initiated by ten nations including India, with the same purpose. The telescope once completed will be the world’s largest and most sensitive radio telescope.

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