World’s Largest Telescope Detects Extragalactic Neutral Hydrogen Emission for the First Time

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FAST Telescope

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The Five-hundred-meter Aperture Spherical radio Telescope (QUICK) is a radio telescope situated in southwest China. It includes a repaired 500 m (1,600 feet) size meal built in a natural anxiety in the landscape. It is the world’s biggest filled-aperture radio telescope.

The Five-hundred-meter Aperture Spherical Radio Telescope (QUICK) is the biggest telescope with the greatest level of sensitivity on the planet. Extragalactic neutral hydrogen detection is among crucial clinical objectives of FAST.  

Recently, a worldwide research study group led by Dr. CHENG Cheng from Chinese Academy of Sciences South America Center for Astronomy (CASSACA) observed 4 extragalactic galaxies by utilizing the FAST 19-beam receiver, and found the neutral hydrogen line emission from 3 targets with just 5 minutes of direct exposure each. This is the very first publication for FAST to discover extragalactic neutral hydrogen.

The term paper was released in Astronomy & Astrophysics Letters

Four Galaxies FAST Observation

The optical color pictures of the 4 galaxies for QUICK observation. The red shapes are the previous CO observation by ALMA. The white spectra in each panel are the arise from QUICK. Credit: CASSACA

Neutral hydrogen gas is the most prolonged baryons in galaxies, while cold gas traced by CO is more focused to a galaxy center (red shape in Fig.1). “With dynamical measurements of neutral hydrogen and CO, we can estimate the mass distribution of galaxies at different radii,” stated Dr. CHENG, very first author of the research study.  

Dynamical masses of these 4 galaxies approximated from the recently observed neutral hydrogen line were 10 times greater than the observed baryon masses, showing contribution of dark matter.

On the other hand, dynamical masses approximated utilizing previous CO observations were comparable to their observed baryon masses. Therefore, the brand-new FAST observation highlighted its capability of studying dark matter in galaxies utilizing the neutral hydrogen 21cm emission line.

The QUICK observation of these galaxies was a fundamental part of a worldwide research study job, the Valparaíso ALMA Line Emission Survey (VALES), led by Prof. Edo Ibar from Valparaiso University in Chile.  

The VALES is a job of observing star-forming galaxies utilizing first-rate worldwide centers such as Sloan Digital Sky Survey (SDSS), Herschel Space Observatory, Atacama Large Millimeter Array (ALMA), Atacama Pathfinder Experiment telescope (PEAK) and Very Large Telescope (VLT).

QUICK, with the unpreceded level of sensitivity, supplies a unique opportunity to observe the extra-galactic neutral hydrogen, and for that reason has actually been contributed to the list of modern-day huge centers utilized by this worldwide partnership.

Reference: “The atomic gas of star-forming galaxies at z ∼ 0.05 as revealed by the Five-hundred-meter Aperture Spherical Radio Telescope” by Cheng Cheng, Edo Ibar, Wei Du, Juan Molina, Gustavo Orellana-Gonzáles, Bo Zhang, Ming Zhu, Cong Kevin Xu, Shumei Wu, Tianwen Cao, Jia-Sheng Huang, Roger Leiton, Thomas M. Hughes, Chuan He, Zijian Li, Hai Xu, Y. Sophia Dai, Xu Shao and Marat Musin, 29 June 2020, Astronomy & Astrophysics Letters
DOI: 10.1051/0004-6361/202038483



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