The team of scientists from the prestigious Inter University Centre for Astronomy and Astrophysics (IUCAA) have made a groundbreaking discovery. The IUCAA team has detected one of the early galaxies, AUDFs01 with AstroSat. This significant galaxy is present in the Hubble Extreme Deep field, 9.3 billion light years from Earth. The dedicated team is made up of scientists from India, Switzerland, France, USA, Japan and the Netherlands.
Understanding the Hubble eXtreme Deep Field (XDF)
The Hubble Extreme Deep Field or XDF is a unique portion of space containing around 5,500 galaxies. The oldest among them are seen as they were in the past, approximately 13.2 billion years ago. This intricate data was collected over a decade by the well-known Hubble Space Telescope.
About Hubble Space Telescope
Hubble Space Telescope (HST), or simply known as Hubble, was launched into Low Earth orbit in 1990 and remarkably continues to function till date. It is among the largest and most versatile space telescopes ever created.
Key Points of the Recent Discovery
The recent discovery of the galaxy was made possible using the UltraViolet Imaging Telescope (UVIT) on AstroSat. Interestingly, AstroSat detected Extreme Ultraviolet light from the galaxy. Earlier attempts to detect UV emission from the galaxy using NASA’s Hubble Space Telescope, which is considerably larger than UVIT, were unsuccessful due to the faintness of the galaxy. AstroSat/UVIT achieved this unique feat as the background noise in the UVIT detector is significantly less than HST’s. The process of collecting observations spanned over 28 hours in October 2016. However, it took nearly two years since then to meticulously analyse the data and confirm that the emission originated from the galaxy.
About AstroSat
AstroSat is a multi-wavelength astronomy mission that operates on an IRS-class (Indian Remote Sensing-Class) satellite in a near-equatorial orbit at a height of 650 km. The Indian launch vehicle PSLV launched it from Satish Dhawan Space Centre, Sriharikota, on September 28, 2015, under the initiative of ISRO. It was India’s first dedicated astronomy mission that focussed on studying celestial sources in X-ray, optical and UV spectral bands simultaneously, using its five unique X-ray and ultraviolet telescopes. A remarkable feature of the AstroSat mission is that it allows the simultaneous multi-wavelength observations of various astronomical objects using a single satellite.
Detection of the Early Galaxy
Before the Big Bang, the universe consisted of only particles like electrons and protons. As the universe started to cool, these particles began combining into ionized atoms of hydrogen and some helium. This creation of neutral atoms allowed light to pass through the universe, rendering it transparent, although still dark due to the absence of stars, hence called the ‘dark ages’. After a few hundred million years, this dark age ended with the formation of the first stars and galaxies. The formation process released an immense amount of energy that re-ionized neutral atoms and emitted UV lights. These early UV lights are crucial for detecting the earliest astronomical objects.
Importance of Space Telescopes
The chances of extreme-UV photons escaping their host galaxy and being detected by a telescope on Earth are minimal. This is why such detections are done using telescopes placed in space like HST and AstroSat.
The Future of Cosmological Research
The detection of UV emission from AUDFs01 opens up new avenues in our understanding of the universe. This discovery can help uncover details about the Big Bang, end of the dark ages and formation of early stars and galaxies, thereby giving a significant boost to ongoing cosmological research.