Abstract:
It was quite a surprise to learn thousands of millisecond-duration radio bursts are happening every day, of yet unknown physical origin. These bursts are named as fast radio bursts (FRBs). Despite having more than 50 theoretical models proposed, we still do not understand how they happen. The physical origin of FRBs has been one of the most urgent questions in astronomy and physics.
Why does the origin of FRBs remain unknown? One of the major challenges is the difficulty in pinpointing the exact locations of FRBs. Current survey telescopes lack the resolution needed to accurately determine their positions, hindering our ability to trace them back to their origins. Accurately pin-pointing FRB positions is one of the most urgent tasks to understand the origins of FRBs.
To address this need, we require a new type of telescope capable of monitoring a vast area of the sky while also pinpointing FRB positions with the accuracy needed for such short-duration events. The Bustling Universe Radio Survey Telescope in Taiwan (BURSTT) aims to accomplish this by deploying arrays of dipole antennas with a field of view of ten thousand square degrees in effective bandwidth between 300 and 800 MHz. Cross-correlation of data from the main Fushan station and three outrigger stations with ~150km baseline in Taiwan offers an angular resolution of ~1”, enabling us to identify the unprecedented number of ~100 FRB host galaxies each year.
In addition, the NTHU is constructing an overseas outrigger station in Ogasawara island, Japan. With the 2000km baseline, the Ogasawara outrigger station will enable us to achieve ~0.1 sub-arcseconds resolution in localizing the FRBs. This precision will not only help us identify the host galaxies of FRBs but also pinpoint the exact locations of FRBs within these galaxies, providing crucial insights into their underlying physics.
The main array, comprising 256 antennas, along with three outrigger arrays in Taiwan, has already been fully deployed. The Ogasawara station is scheduled for completion in December. By localizing the unprecedented number of hundreds of FRBs each year, the BURSTT will bring a breakthrough to FRB research.
Title: High-cadence monitoring observations of methanol masers in massive-star forming regions using Ibaraki 32-m radio telescopes
Speaker: Yoshinori Yonekura (Ibaraki)
Date: November 28 at 12:00
Location: R501, General Building II
Abstract:
Radio astronomy group at Ibaraki University is now operating two radio telescopes named as Hitachi 32-m antenna and Takahagi 32-m antenna. These two telescopes had been used for satellite communications at 4 and 6 GHz by Japanese telecommunication company KDDI, and were decommissioned in 2007 March. Then, these antennas were handed over to the NAOJ on 2009 January 31. We have started conversion from telecommunication antennas to radio telescopes at 6-25 GHz and we started high-cadence single-dish monitoring observations of ~500 methanol masers from 2012 December.Observations are made 14 hours per day, everyday. This is the largest monitoring observations in the world. The data are available at the iMet website. We newly detected more than 20 methanol masers with periodic flux variations, which doubled the total number of the periodic masers. We also detected several sudden flux increase. Thanks to the international follow-up observation network M2O, the 2019 flux increase that we have detected, was identified to beoccurred by the accretion of materials around the forming stars to the central massive star.
