[Paper Review] Sciences with Thai National Radio Telescope

Phrudth Jaroenjittichai, Koichiro Sugiyama+45 more|arXiv (Cornell University)|Oct 10, 2022

Radio Astronomy Observations and Technology4 citations

TL;DR

This white paper outlines the scientific potential of the Thai National Radio Telescope (TNRT), a single-dish radio telescope in Chiang Mai, Thailand, operational since mid-2022. It proposes key science in pulsars, fast radio bursts, star-forming regions, active galactic nuclei, evolved stars, chemically peculiar stars, and geodesy across L/C/X/Ku/K/Q/W bands (1–115 GHz), with major contributions to Very Long Baseline Interferometry (VLBI) through improved uv-coverage and imaging quality due to its strategic northern hemisphere location.

ABSTRACT

This White Paper summarises potential key science topics to be achieved with Thai National Radio Telescope (TNRT). The commissioning phase has started in mid 2022. The key science topics consist of "Pulsars and Fast Radio Bursts (FRBs)", "Star Forming Regions (SFRs)", "Galaxy and Active Galactic Nuclei (AGNs)", "Evolved Stars", "Radio Emission of Chemically Peculiar (CP) Stars", and "Geodesy", covering a wide range of observing frequencies in L/C/X/Ku/K/Q/W-bands (1-115 GHz). As a single-dish instrument, TNRT is a perfect tool to explore time domain astronomy with its agile observing systems and flexible operation. Due to its ideal geographical location, TNRT will significantly enhance Very Long Baseline Interferometry (VLBI) arrays, such as East Asian VLBI Network (EAVN), Australia Long Baseline Array (LBA), European VLBI Network (EVN), in particular via providing a unique coverage of the sky resulting in a better complete "uv" coverage, improving synthesized-beam and imaging quality with reducing side-lobes. This document highlights key science topics achievable with TNRT in single-dish mode and in collaboration with VLBI arrays.

Motivation & Objective

• To define and prioritize key scientific objectives for the Thai National Radio Telescope (TNRT) in single-dish and VLBI modes.
• To demonstrate how TNRT’s geographical location enhances global Very Long Baseline Interferometry (VLBI) networks such as EAVN, LBA, and EVN by improving uv-coverage and image fidelity.
• To enable high-cadence monitoring of transient and variable radio sources, including pulsars, masers, and fast radio bursts.
• To support astrophysical studies of star formation, evolved stars, and galactic kinematics through high-resolution spectral and imaging observations.
• To contribute to geodetic VLBI in K-band for tectonic and geophysical studies in Southeast Asia.

Proposed method

• Simulating uv-coverage improvements for TNRT in collaboration with LBA and EVN using the SCHED software and station coordinates from official array databases.
• Conducting simulations of synthesized beam quality and side-lobe suppression in VLBI configurations involving TNRT, particularly in L-band and K-band.
• Utilizing the TNRT’s agile observing system for time-domain astronomy, including high-cadence flux and polarization monitoring of variable sources.
• Performing unbiased thermal molecular and maser line surveys in star-forming regions and evolved stars using high-frequency bands (K/Q/W bands).
• Applying VLBI techniques to measure astrometry of circumstellar masers and jet structures in active galactic nuclei and high-mass star-forming regions.
• Leveraging the TNRT’s 260-mo4 site in northern Thailand for geodetic observations in K-band, supporting the VGOS network and tectonic monitoring.

Experimental results

Research questions

• RQ1 How will TNRT enhance the uv-coverage and imaging quality of global VLBI networks such as EAVN, LBA, and EVN?
• RQ2 What is the contribution of TNRT to the detection and characterization of fast radio bursts and pulsar timing arrays?
• RQ3 How can high-cadence radio monitoring with TNRT reveal magnetic field variability and burst activity in star-forming regions?
• RQ4 To what extent can TNRT improve the detection of cosmologically important megamasers in galaxies and the astrometry of circumstellar masers?
• RQ5 What is the role of TNRT in geodetic VLBI for monitoring tectonic activity in Southeast Asia?

Key findings

• TNRT significantly improves uv-coverage in VLBI arrays, especially for sources in the southern and northern celestial hemispheres, due to its strategic location in northern Thailand.
• Simulations show that TNRT enhances synthesized beam quality and reduces side-lobes in VLBI imaging, particularly when co-observing with LBA and EVN in L- and K-bands.
• TNRT’s single-dish capability enables high-cadence monitoring of flux and polarization variability in star-forming regions, revealing periodic and bursting behavior.
• The telescope supports high-resolution spectral surveys of thermal molecular lines and masers in evolved stars, enabling phase-lag measurements and distance determinations.
• TNRT contributes to geodetic VLBI in K-band, with specifications including baseline lengths and 5σ sensitivities calculated for collaborations with LBA and EVN.
• The collaboration with EAVN, LBA, and EVN is expected to improve astrometric precision and imaging fidelity for sources such as M87, based on simulation results using AIPS and Difmap software.