IUCAA - Khagol # 129 - Oct 2022 - English

| KHAG L | No. 129 - OCTOBER 2022 | 09 study of interstellar dust, the study of interstellar dust extinction, and the study of AGNand X-ray sources. A programme wherein researchers from all o v e r t he c oun t r y c an a v a i l t he infrastructure facilities available at IUCAA to pursue their research while they continue to remain affiliated with their parent institution. The associate who is either a faculty member of an Indian university or a post-graduate department in a college carries out the research in their institution with scheduled short and long- duration visits to IUCAA and collaborates with scientists from the institution. It aids research scholars from remote areas of the country to contribute toward cutting- edge research andwork with the best in the field. Prof. Gogoi expressed her thoughts by saying that “the current work is an inspiration to young researchers of the country as this utilises data from India's indigenous satellite, AstroSat and also showcases the glorious association of IUCAA and a university, which surely will motivate the researchers working in Indian Universities. We look forward to enhancing this type of collaborative endeavour between IUCAA and Tezpur University” The young stars, beyond the boundary of these dwarfs, are found in the formof star- forming complexes or clumps indicating unusually high condensation of cold gas. It has been a mystery how some small galaxies like these can have such active star formation. These observations suggest that accreting gas in the far outer parts can be forced to move towards the centre because of the inward torques exerted by giant gas and stellar complexes. Thismigration builds up the central density over the lifetime of the galaxy. The Ultraviolet (UV) Imaging Telescope on AstroSat was used to detect extended UV emission from the outskirts of 12 BCDs that are 1.5 - 3.9 billion light-years away. Such extended far-ultraviolet emission implies young stars that are forming now on the periphery of these galaxies where no stars older than 150 million years were spotted before. UVIT's resolving power and deep field imaging techniques have been the key to spotting these very young, large star- forming clumps that move inside the optical boundary within a short timescale to grow these galaxies. We are witnessing the 'live' formation of these far-way dwarf galaxies The key challenging task has been to establish the detection of these faint, extremely blue star-forming clumps with million solar masses. At slightly larger distances, the UVIT would not resolve the galaxies and we do not have an example of an extended UV disk in present-day dwarf galaxies. The redshift of these 12 dwarfs has been optimal to probe these blue clumpy structures in the outskirts. The discovery teaches us how surprisingly the star formation can proceed in relatively pristine low-metallicity gas. These outer disks are unstable towards fragmentation, even though these dwarfs must be dominated by darkmatter. Prof. Somak Raychaudhury, Director of IUCAA Pune, points out how this is another major success story for the visiting Associateship programme of the UGC at IUCAA: “There are currently 200 such associates who visit IUCAA with their students from time to time and always interact online, and many collaborate among themselves on national and international projects, with or without IUCAA faculty. Major national facilities thus get connected to the educators and students who form the bulk of the researchers in India. At IUCAA, we train many of them on how to use facilities such as ISRO's AstroSat, and enable access to the resources that are necessary for world- class research” The researchers feel privileged to have such a state-of-the-art observational facility from the Indian Space Research Organisation that led to this important discovery. Future endeavours to create such facilities would ensure scientific excellence and opportunities for young aspirants to nurture their curiosity as well as make a significant contribution to science and development. Cutting-edge technology being accessible to young researchers has increased the involvement of the youth in the development of science to better understand the universe as awhole. Changing-look AGNs - Dr. Ritesh Ghosh Being a young inquisitive kid, his journey from reading a book about the moon landing to working in NASA has been quite exciting. With a formal education in physics, Dr. Ritesh Ghosh , intrigued by the enormity of the universe very religiously questions the behaviour of the most luminous and powerful objects in the universe known to us – SUPER MASSIVE BLACKHOLES (SMBH). As a post-doctoral fellow at the Inter-University Center for Astronomy and Astrophysics, Pune, India, Dr Ghosh has extensively worked on X-ray data analysis and the multi-wavelength study of the unresolved central region of the AGN to disentangle the disk-corona-jet emission in radio-loud AGNs, the origin of reflection features in the X-ray spectra of