A team of Indian radio astronomers has announced the discovery of 34 new giant radio sources (GRSs) using the Giant Metrewave Radio Telescope (GMRT). Located near Khodad village, approximately 90 km north of Pune, the GMRT was built and is operated by the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of Fundamental Research (TIFR).
Survey Details
From 2010 to 2012, the GMRT conducted the TIFR GMRT Sky Survey (TGSS) to map the radio sky at 150 MHz. This survey covered about 90% of the sky and was utilized for the recent research due to the GMRT’s sensitivity and low frequency capabilities.
Team Composition
The research team includes:
- Netai Bhukta (SKBU, India) – PhD student
- Souvik Manik (MCC, India) – PhD student
- Sabyasachi Pal (MCC, India) – Astronomer
- Sushanta K Mondal (SKBU, India) – Astronomer
The findings have been published in the Astrophysical Journal Supplement Series (ApJS) by the American Astronomical Society.
Observational Challenges
Prof. Ishwara Chandra C. H. Dean from the GMRT Observatory noted that understanding the late stages of radio galaxy evolution is crucial yet observationally challenging. Historically, only about 100 giant radio sources were known 20 years ago, but advancements in telescopes, particularly low-frequency ones like GMRT and LOFAR, have increased the number to a few thousand.
New Findings
The research uncovered several sources that defy previous conventions about GRS environments. The discovery of GRSs at larger distances than previously known indicates that many more giant sources exist and are located farther from Earth.
Insights into Universe Structure
Dr. Sushanta K Mondal explained that studying these giant radio galaxies helps scientists understand the large-scale structure of the universe and the relationship between black hole activity and the evolution of radio galaxies.
Challenges in Detection
Dr. Sabyasachi Pal highlighted the difficulty in detecting GRSs, as the radio emissions from the radio jets become less visible at high frequencies. The low-frequency capabilities of the GMRT were crucial in discovering the 34 new sources, including two in dense galaxy cluster environments that challenge existing theories about GRS formation.
Upcoming Studies
Researchers plan to present new GRG samples and detailed physical properties in forthcoming articles. These studies will include multi-wavelength observations to further explore the mystery of GRS formation and their environment.
Characteristics and Mysteries
GRSs are among the largest objects in the universe, with a supermassive black hole at their core. These black holes, ranging from ten million to one billion times the mass of the Sun, drive the massive jets of hot plasma that create the observable radio lobes. The enormous size of GRSs makes them significant for understanding radio source evolution and the intergalactic medium.
Detection Challenges
Detecting GRSs is challenging because the bridge emission connecting the lobes is often not visible. Low-frequency surveys are more effective in identifying these sources due to the brighter appearance of aged plasma at these frequencies.
Multiple-Choice Questions (MCQs):
1. What is the main objective of the TIFR GMRT Sky Survey (TGSS)?
a) To study high-frequency radio emissions
b) To map the radio sky at 150 MHz
c) To discover new black holes
d) To analyze optical galaxy images
Answer: b) To map the radio sky at 150 MHz
2. Where is the Giant Metrewave Radio Telescope (GMRT) located?
a) Near Khodad village, 90 km north of Pune
b) Near Mumbai, 150 km south of Pune
c) Near New Delhi, 200 km east of Pune
d) Near Chennai, 120 km west of Pune
Answer: a) Near Khodad village, 90 km north of Pune
3. How many new giant radio sources (GRSs) were discovered in the recent research?
a) 10
b) 20
c) 34
d) 50
Answer: c) 34
4. Which type of telescope was crucial for detecting the new GRSs?
a) Optical telescope
b) High-frequency radio telescope
c) Low-frequency radio telescope
d) Infrared telescope
Answer: c) Low-frequency radio telescope
5. What was a significant finding about the newly discovered GRSs?
a) They are all located in low-density environments
b) They are closer to Earth than previously known
c) They include sources in dense galaxy cluster environments
d) They do not include any new discoveries
Answer: c) They include sources in dense galaxy cluster environments