By Udita Shukla
A recent discovery by NASAs Hubble and Spitzer space telescopes has yielded an amazingly magnified image of a far-away, primitive galaxy. Christened as SPT0615-JD, the galaxy was discovered as part of Hubble’s Reionization Lensing Cluster Survey (RELICS) and its partner S-RELICS Spitzer programme. According to Dan Coe, Principal Investigator of RELICS, RELICS was designed to discover distant galaxies like these that are magnified brightly enough for detailed study,.
Aspects of the galaxy
Nearly five hundred million years in age, SPT0615-JD is a fairly young candidate on a cosmological scale. This is because the age of our universe is 14.7 billion years, which isolates this galaxy as one of the very few detected objects from the epoch of preliminary galaxy formation.
Intriguingly, SPT0615-JD presents a fortuitous concurrence of events. The image extracted from the telescopes shows an amplified version, stretched into the form of an arc. This occurs when light rays emanating from a distant object suffer distortion in their path due to the presence of another massive object (in this case, an extremely dense galaxy cluster). In other words, the phenomenon mentioned above facilitates bigger and clearer images of far-away astrophysical objects.
Understanding features by gravitational lensing
This phenomenon is known as gravitational lensing. Consequently, light coming from SPT0615-JD got ‘lensed’ (or, distorted) by the intense gravitational field of the galaxy cluster lying in the foreground. In the words of Brett Salmon, Space Telescope Science Institute, USA, No other candidate galaxy has been found at such a great distance that also gives you the spatial information that this arc image does.
Instances, where bending of light by an intervening gravitational field is visually detectable, comes under the umbrella of strong gravitational lensing. Investigating the effects of lensing has the potential to reveal appreciably granular information about the actual size and shape of the candidate galaxy. Moreover, SPT0615-JD is believed to have been born not many years after the Big Bang, the cataclysmic explosion that is widely accepted to give birth to the current universe as we know it. This attaches all the more significance to the discovery as it can unveil the early scenario of the universe.
Initial analyses place an upper cap of around three billion solar masses to the galaxys mass with an approximate age of thirteen billion years. Also, the dimension is calculated to be nearly 2,500 light-years across.
The end and the beginning
Although SPT0615-JD is situated at the extreme periphery of Hubble’s detection capabilities, it lies well within the ambit of NASAs James Webb Space Telescopes (JWST) field of view which is scheduled to be launched by mid-2019. As per Salmon, “This galaxy is an exciting target for science with the Webb telescope as it offers the unique opportunity for resolving stellar populations in the very early universe,.
Acquiring flawless precision capabilities and deep space vision is still a work in progress, and one of the primary constraints to the detection of galaxies and clusters in space. The Hubble Space Telescope, a joint venture by NASA, the European Space Agency and the Space Telescope Science Institute, will be decommissioned by the 2020s. Therefore, the upcoming JWST has already triggered expectations from across the scientific community. Armed with enhanced technical functionalities and a deeper vision, the team studying SPT0615-JD predicts unprecedented lensing to deliver a mine of data which will prove to be a strong foundation for its study from JWSTs perspective (post its launch).
Future prospects
One of the most pursued and active areas of cosmological research is the identity and dynamics of dark matter and dark energy. Undetectable by usual astronomical methods and entirely non-interactive with light, dark energy accounts for about seventy-five percent, whereas, dark matter occupies around twenty-one percent, of the known universe. Dark matter interacts only gravitationally and is responsible for gravitationally bending images of most galaxies and quasars.
Discoveries such as the current one can help astronomers decode the structure and composition dark matter, as most of the lensing is usually attributed to dark matter. The reason behind this is the quantity of dark matter in intervening galaxy clusters to outweigh the other by a factor of six or so.
Occasionally, strongly lensed distant galaxies can appear twisted into strangely warped or pulled-out shapes. Prominent examples include the Abell 2218 cluster and the Bullet Cluster. This further facilitates the study of the amount and distribution of the dark matter residing in between the distant galaxy (whose image has been lensed) and us.
Undoubtedly, our universe is not only a Pandoras box of the most inexplicable oddities of nature but also a mirror to the great unknown that lies beyond.
Featured Image Source: NASA/ESA/STScI/B. Salmon