Arecibo data still has astronomers in a spin

Date:
December 1, 2021
Source:
International Centre for Radio Astronomy Research
Summary:
Data collected by the Arecibo Radio Telescope before it collapsed
late last year will help astronomers better understand how our
local neighbourhood of galaxies formed. Arecibo was the world's
largest single- dish radio telescope until it was surpassed in
2016 by China's Five- hundred-meter Aperture Spherical Telescope
(FAST). At the end of 2020, Arecibo's 900-ton receiver platform
suddenly and spectacularly fell onto the dish below, destroying
the telescope.



FULL STORY ==========================================================================
Data collected by the Arecibo Radio Telescope before it collapsed
late last year will help astronomers better understand how our local neighbourhood of galaxies formed.


========================================================================== Arecibo was the world's largest single-dish radio telescope until it
was surpassed in 2016 by China's Five-hundred-meter Aperture Spherical Telescope (FAST). At the end of 2020, Arecibo's 900-ton receiver platform suddenly and spectacularly fell onto the dish below, destroying the
telescope.

A team of astronomers from the University of Western Australia and
the International Centre for Radio Astronomy Research (ICRAR) in Perth
have used Arecibo's observations of nearby galaxies to test the 'Fall relation'.

First presented by S. Michael Fall in 1983, the Fall relation suggests the
mass of stars belonging to a galaxy and its rotation directly correlate
to each other and dictate how a galaxy will grow and evolve.

Funded by the Australian Research Council and published in the journal
Monthly Notices of the Royal Astronomical Society (MNRAS), the new study
tests this relationship using data collected from 564 galaxies of varying shapes and ages, making it the largest representative sample of its kind.

Lead author and PhD candidate Jennifer Hardwick said the study would
help researchers better understand how a wide range of galaxies evolved
and formed, including our galaxy, the Milky Way.



========================================================================== "Although the Fall relation was first suggested almost 40 years ago,
previous research to refine its properties had small samples and was
limited in the types of galaxies used," Hardwick said.

"This work challenges astronomers' current understanding of how
galaxies change over their lifetime and provides a constraint for future researchers to develop these theories further." Prior research into
this relationship has been restricted by the type and number of known
galaxies with resolved accurate data, which researchers use to measure
galaxy rotation through the Doppler effect.

The study shows that the relationship between the mass of stars and a
galaxy's rotation is not what we first thought, with different galaxy
types displaying a different relationship between the two properties.

"Because galaxies evolve over billions of years, we have to work with
snapshots of their evolution -- taken from different stages of their
life -- and try to piece together their journey." This process has left astronomers with lots of unanswered questions about a galaxy's lifecycle.



==========================================================================
"By developing a better understanding of galaxies properties now, we
can incorporate these into our simulations to work backwards," she said.

Associate Professor Luca Cortese, Ms Hardwick's supervisor and co-author,
said the study shows the importance of revisiting research as our
technology advances.

"This creates a cycle of technological development, resulting in new discoveries which push for further advances," he said. "However, before
getting to the new discoveries, it is critical to revisit previous
knowledge to make sure that our foundations are correct.

"Since the dawn of extragalactic astronomy, it was clear that angular
momentum is a key property for understanding how galaxies form and
evolve. However, due to the difficulty of measuring angular momentum,
direct observational constraints to our theory have been lacking.

"This work provides an important reference for future studies, offering
one of the best measurements of the connection between angular momentum
and other galaxy properties in the local Universe." The research also reinforces the importance of the Arecibo Radio Telescope to astronomy
over the past 58 years, even after its forced retirement in 2020.

"Despite the fact that the Arecibo Radio Telescope suddenly collapsed
last year, observations of atomic hydrogen content in galaxies carried
out with this facility still provide the deepest census of gas content
in galaxies," Associate Professor Cortese said.

"We will have to wait for the second half of this decade before these
kinds of observations are superseded by data obtained with the precursors
of the Square Kilometre Array, such as Australia's SKA Pathfinder
Telescope (ASKAP), South Africa's Karoo Array Telescope (MeerKAT) and
China's Five-hundred-meter Aperture Spherical radio Telescope (FAST)." ========================================================================== Story Source: Materials provided by International_Centre_for_Radio_Astronomy_Research. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Jennifer A Hardwick, Luca Cortese, Danail Obreschkow, Barbara
Catinella,
Robin H W Cook. xGASS: characterizing the slope and scatter of the
stellar mass-angular momentum relation for nearby galaxies. Monthly
Notices of the Royal Astronomical Society, 2022; 509 (3): 3751 DOI:
10.1093/mnras/stab3261 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211201112000.htm

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