MYSTERIOUS OBJECT UNLIKE ANYTHING ASTRONOMERS HAVE SEEN BEFORE

Jan 27, 2020
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January 27, 2022

A team mapping radio waves in the Universe has discovered something unusual that releases a giant burst of energy three times an hour, and it’s unlike anything astronomers have seen before.

The team who discovered it think it could be a neutron star or a white dwarf—collapsed cores of stars—with an ultra-powerful magnetic field.

Spinning around in space, the strange object sends out a beam of radiation that crosses our line of sight, and for a minute in every twenty, is one of the brightest radio sources in the sky.


Astrophysicist Dr Natasha Hurley-Walker, from the Curtin University node of the International Centre for Radio Astronomy Research, led the team that made the discovery.

“This object was appearing and disappearing over a few hours during our observations,” she said.
“That was completely unexpected. It was kind of spooky for an astronomer because there’s nothing known in the sky that does that.

“And it’s really quite close to us—about 4000 lightyears away. It’s in our galactic backyard.” Indeed.

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This image shows the Milky Way as viewed from Earth. The star icon shows the position of the mysterious repeating transient. Credit: Dr Natasha Hurley-Walker (ICRAR/Curtin).

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This image shows a new view of the Milky Way from the Murchison Widefield Array, with the lowest frequencies in red, middle frequencies in green, and the highest frequencies in blue. The star icon shows the position of the mysterious repeating transient. Credit: Dr Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM Team.

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The new radio is transient in the sky, as it would have been seen at the MWA during the night in March 2018, when it was active. The source is shown with a large white star marker, but would be invisible to the naked eye. Image source: Stellarium

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The location of the source in the sky in January 2022, marked with a large white star marker. At this time of year, it is above the horizon during the day. Image source: Stellarium

The object was discovered by Curtin University Honours student Tyrone O’Doherty using the Murchison Widefield Array (MWA) telescope in outback Western Australia and a new technique he developed.

“It’s exciting that the source I identified last year has turned out to be such a peculiar object,” said Mr O’Doherty, who is now studying for a PhD at Curtin.
“The MWA’s wide field of view and extreme sensitivity are perfect for surveying the entire sky and detecting the unexpected.”

MWA tile 106.jpeg
Tile 107, or “the Outlier” as it is known, is one of 256 tiles of the MWA located 1.5km from the core of the telescope. The MWA is a precursor instrument to the SKA. Photographed by Pete Wheeler, ICRAR (Note the Southern Hemisphere's Large Magellanic Cloud (LMC)*, a dwarf galaxy in a gravitational orbit with the Milky Way, above and to the left of the distant rock formation.)

Objects that turn on and off in the Universe aren’t new to astronomers—they call them ‘transients’.
ICRAR-Curtin astrophysicist and co-author Dr Gemma Anderson said that “when studying transients, you’re watching the death of a massive star or the activity of the remnants it leaves behind”.”

‘Slow transients’—like supernovae—might appear over the course of a few days and disappear after a few months.
‘Fast transients’—like a type of neutron star called a pulsar—flash on and off within milliseconds or seconds.
But Dr Anderson said finding something that turned on for a minute was really weird.

She said the mysterious object was incredibly bright and smaller than the Sun, emitting highly-polarised radio waves—suggesting the object had an extremely strong magnetic field.


A team mapping radio waves in the Universe has discovered something unusual that releases a giant burst of energy three times an hour, and it’s unlike anything astronomers have seen before. An animation showing the emission profile of the radio source. Credit: Dr Natasha Hurley Walker (ICRAR/Curtin) and the GLEAM Team.

Dr Hurley-Walker said the observations match a predicted astrophysical object called an ‘ultra-long period magnetar’.

“It’s a type of slowly spinning neutron star that has been predicted to exist theoretically,” she said.
“But nobody expected to directly detect one like this because we didn’t expect them to be so bright.
“Somehow it’s converting magnetic energy to radio waves much more effectively than anything we’ve seen before.”

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An artist’s impression of what the object might look like if it’s a magnetar. Magnetars are incredibly magnetic neutron stars, some of which sometimes produce radio emission. Known magnetars rotate every few seconds, but theoretically, “ultra-long period magnetars” could rotate much more slowly. Credit: ICRAR.


In this video, lead researcher Dr Natasha Hurley-Walker from the Curtin University node of the International Centre for Radio Astronomy Research answers some questions about the discovery. Credit: ICRAR.

Dr Hurley-Walker is now monitoring the object with the MWA to see if it switches back on.
“If it does, there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it,” she said.
Dr Hurley-Walker plans to search for more of these unusual objects in the vast archives of the MWA.

“More detections will tell astronomers whether this was a rare one-off event or a vast new population we’d never noticed before,” she said.
MWA Director Professor Steven Tingay said the telescope is a precursor instrument for the Square Kilometre Array—a global initiative to build the world’s largest radio telescopes in Western Australia and South Africa.

“Key to finding this object, and studying its detailed properties, is the fact that we have been able to collect and store all the data the MWA produces for almost the last decade at the Pawsey Research Supercomputing Centre. Being able to look back through such a massive dataset when you find an object is pretty unique in astronomy,” he said.

“There are, no doubt, many more gems to be discovered by the MWA and the SKA in coming years.”

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Pawsey Supercomputing Research Centre was used to store and share the data used by this project. Credit: Pawsey Supercomputing Research Centre.

SKA-Low_Wide-Angle-Composite.jpeg
Composite image of the SKA-Low telescope in Western Australia. The image blends a real photo (on the left) of the SKA-Low prototype station AAVS2.0 which is already on-site, with an artist’s impression of the future SKA-Low stations as they will look when constructed. These dipole antennas, which will number in their hundreds of thousands, will survey the radio sky at frequencies as low as 50Mhz. Credit: ICRAR, SKAO.

The Murchison Widefield Array is located on the Murchison Radio-astronomy Observatory in Western Australia. The observatory is managed by CSIRO, Australia’s national science agency, and was established with the support of the Australian and Western Australian Governments. We acknowledge the Wajarri Yamatji as the traditional owners of the observatory site.

The Pawsey Supercomputing Research Centre in Perth–a Tier 1 publicly funded national supercomputing facility–helped store and process the MWA observations used in this research.

Shanghai Astronomical Observatory (SHAO) is a member of the MWA. China’s SKA Regional Centre Prototype, funded by the Ministry of Science and Technology of China and the Chinese Academy of Sciences, is hosted by SHAO and contributed to processing the MWA observations used in this research.


A radio transient with unusually slow periodic emission’, published in Nature on January 27th, 2022.

INTERVIEWS:
Dr Natasha Hurley-Walker | ICRAR / Curtin University | Natasha.Hurley-Walker@curtin.edu.au
Tyrone O’Doherty | ICRAR / Curtin University | tyrone.odoherty@postgrad.curtin.edu.au
Dr Gemma Anderson | ICRAR / Curtin University | gemma.anderson@curtin.edu.au
Dr Xiang Zhang | Shanghai Astronomical Observatory | xiang.zhang@shao.ac.cn

MEDIA ENQUIRIES:
Pete Wheeler | ICRAR | Pete.Wheeler@icrar.org | +61 423 982 018
Lucien Wilkinson | Curtin University | Lucien.Wilkinson@curtin.edu.au | +61 401 103 683

See: https://www.icrar.org/repeating-transient/

While I appreciate Brandon Spector's article here, in Live Science, very much, I wanted to examine the source article, Dr Hurley-Walker and a bit more on Curtin University in Perth, Australia. I find this extremely exciting and I applaud Dr Hurley-Walker and her team for their outstanding work. Additionally, it is unique that the antennas used for this breakthrough, which can tackle frequencies down to 50Mhz, are so low to the ground. Usually, one envisions of antennas hoisted up in the air on platforms, in long wires, in parabolic dishes or in vertical whips.

Dr Natasha Hurley-Walker obtained her PhD in radio astronomy from the University of Cambridge in 2010, and moved to Australia to help commission the Murchison Widefield Array, a low-frequency precursor to the Square Kilometer Array. Using this telescope, she created a panoramic view of the Universe at low radio frequencies: the GaLactic and Extragalactic All-sky MWA Survey. From 2020 she has held an ARC Future Fellowship to create GLEAM-X, ten times deeper, opening new possibilities in exploration.

University of Cambridge, UK — PhD Radio Astronomy
University of Bristol, UK — MSci Physics with Astrophysics

Current: International Centre for Radio Astronomy Research, Curtin University, Perth, Australia

See: https://astronomy.curtin.edu.au/home/about/

The Curtin Institute of Radio Astronomy (CIRA) is Curtin’s link with the International Centre for Radio Astronomy Research (ICRAR). We are proud to have helped bring the Square Kilometre Array to Australia and we look forward to working with our partners to make the telescope a reality.

CIRA covers a wide range of projects in the area of radio astronomy, including aspects of next generation telescopes such as the MWA and ASKAP as well as the SKA at the Murchison Radio-astronomy Observatory. Learn more about our research and people at the links above.

Hartmann352

* Large Magellanic Cloud - (LMC) is a dwarf irregular galaxy located on the border between the constellations Dorado and Mensa. The galaxy is a satellite of the Milky Way and a member of the Local Group of galaxies, which includes about 30 galaxies that are loosely bound together by their gravitation.

The Large Magellanic cloud lies an an approximate distance of 163,000 light years, or just under 50 kiloparsecs from Earth. Covering several degrees of the sky, the Large Magellanic Cloud is quite large in size, as its name indicates, and easy to find without binoculars for observers in the southern hemisphere, from locations in Australia.

Both Magellanic Clouds are companions to our galaxy. The Large Magellanic Cloud is orbiting the Milky Way and is gravitationally bound to it. It is the third nearest galaxy to the Milky Way, with only the Sagittarius Dwarf Spheroidal galaxy in Sagittarius constellation and the Canis Major Dwarf Galaxy in Canis Major lying closer, at 16 and 12.9 kiloparsecs, respectively. (The status of the Canis Major Dwarf as a galaxy is under dispute.)

The Large Magellanic Cloud is often listed as an irregular type galaxy because of its appearance, which is likely the result of the galaxy’s tidal interactions with the Milky Way and the Small Magellanic Cloud (SMC), located in Tucana constellation. The LMC has a prominent bar in its central region, which indicates that it may have previously been a barred spiral galaxy.

The Magellanic Clouds are connected by a bridge of gas, which is a region of active star formation between the two galaxies. The bridge indicates that the Magellanic Clouds are tidally interacting. The galaxies also have have a common envelope of neutral hydrogen, which means that they have been gravitationally bound to each other for a very long time. The Small Magellanic Cloud is more distant from us, lying at a distance of about 200,000 light years from Earth.

The Large Magellanic Cloud (14,000 light years across) has twice the diameter of the Small Magellanic Cloud (7,000 light years), but is signficantly smaller than the Milky Way (100,000 light years).

The LMC is the fourth largest galaxy in the Local Group, smaller in size only than the Andromeda Galaxy (Messier 31), the Milky Way, and the Triangulum Galaxy (Messier 33).

A hypothetical observer looking at the Milky Way from a planet within the Large Magellanic Cloud would be treated to quite a spectacle. With an apparent magnitude of -2.0, the Milky Way would appear more than 14 times brighter than the LMC appears to us, and would span roughly 36° of the sky, which is more than 70 full Moons in width.

The Large Magellanic Cloud was considered to be the nearest external galaxy to our own until 1994, when astronomers discovered the Sagittarius Dwarf Elliptical Galaxy, which is only 80,000 light years distant.

The Magellanic Clouds have both been greatly distorted as a result of tidal interaction with our galaxy, the Milky Way. The three galaxies are connected by trails of neutral hydrogen. The gravity of the Magellanic Clouds has affected the Milky Way, too, distorting the outer regions of our galaxy’s disk.

The LMC is often classified as a Magellanic-type dwarf spiral galaxy because it has a central bar and a spiral arm, but it is sometimes considered an irregular galaxy because of its unusual shape. The galaxy’s central bar appears warped, with its east and west ends closer to the Milky Way than the middle. The galaxy is inclined at 35°. (A galaxy appearing face-on to an observer on Earth would have an inclination of 0°.) The Small Magellanic Cloud, also an irregular dwarf galaxy, shows signs of a bar structure, too, and is also frequently reclassified as a Magellanic spiral.
 
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Mar 4, 2020
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I find this very interesting, but very confusing and disappointing. All of this reporting about GLEAM has no context. What got bright? Did a star, a visible light, get brighter? What is meant by the term radio waves? Was it gamma, x-ray, UV, visible light, IR, MW or low band? Are we now using "bright", to describe the intensity of invisible radio waves?

They say it was a large periodic event, and very puzzling. Exactly.....what was detected? And what was so puzzling about it? What was the emission spectrum? Was it light?

Even a puzzle needs a reference. Some radio waves was detected.......has no reference. An emission means nothing, without the frequencies. The cycle period means nothing, without the frequencies. The 3 month appearance and disappearance means nothing, without the frequencies.

I've read half a dozen articles on this........and no frequencies.

Why is that? The frequencies are the only information that was detected. Is it a secret?

Why is the reporting on this so lame?
 
Jan 27, 2020
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Hayseed, here's the Abstract from the actual Nature.com article "A radio transient with unusually slow periodic emission" by Dr Natasha Hurley-Walker, et al:

"The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has, so far, been quiet beyond the Galactic pulsar population and the long-term scintillation of active galactic nuclei. The low-frequency band*, however, is sensitive to exotic coherent and polarized radio-emission processes, such as electron-cyclotron maser emission from flaring M dwarfs, stellar magnetospheric plasma interactions with exoplanets and a population of steep-spectrum pulsars, making Galactic-plane searches a prospect for blind-transient discovery. Here we report an analysis of archival low-frequency radio data that reveals a periodic, low-frequency radio transient. We find that the source pulses every 18.18 min, an unusual periodicity that has, to our knowledge, not been observed previously. The emission is highly linearly polarized, bright, persists for 30–60 s on each occurrence and is visible across a broad frequency range. At times, the pulses comprise short-duration (<0.5 s) bursts; at others, a smoother profile is observed. These profiles evolve on timescales of hours. By measuring the dispersion of the radio pulses with respect to frequency, we have localized the source to within our own Galaxy and suggest that it could be an ultra-long-period magnetar."

* Low frequency band is typically in the 29.7MHz to 50.0MHz range of frequencies.

See: https://ph.searchimp.com/a-radio-transient-with-unusually-slow-periodic-emission-nature-com-116127.html

You might also be interested in E.F. Keane's work, below, on FRB's:

The Future of Fast Radio Burst Science
E. F. Keane, Max-Planck-Institut fürRadioastronomie Auf dem Hügel 69, 53121 Bonn, Germany

The field of Fast Radio Burst (FRB) science is currently thriving and growing rapidly. The lines of active investigation include theoretical and observational aspects of these enigmatic millisecond radio signals. These pursuits are for the most part intertwined so that each keeps the other in check, characteristic of the healthy state of the field. The immediate future for FRB science is full of promise --- we will in the next few years see two orders of magnitude more FRBs discovered by the now diverse group of instruments spread across the globe involved in these efforts. This increased crop, and the increased information obtained per event, will allow a number of fundamental questions to be answered, and FRBs' potential as astrophysical and cosmological tools to be exploited. Questions as to the exact detailed nature of FRB progenitors and whether or not there are one or more types of progenitor will be answered. Questions as to source counts, the luminosity distribution and cosmological density of FRBs will also be addressed. Looking further ahead, applications involving FRBs at the highest redshifts look set to be a major focus of the field. The potential exists to evolve to a point where statistically robust cosmological tests, orthogonal to those already undertaken in other ways, will be achieved. Related work into FRB foregrounds, as well as how to identify new events in ever more challenging radio-frequency interference environments, also appear likely avenues for extensive investigations in the coming years.
FRBs are characterised by large dispersion measures (DM), the integrated electron density along the line of sight to the source, with values exceeding the maximum Galactic contribution from the interstellar medium (ISM) by as much as 3–5 a factor of 200. To explain such large excess DM values necessitates a large contribution from the intergalactic medium (IGM). As the electron density of the IGM is typically ∼ 10−5 that of the ISM one must immediately infer distances of several gigaparsecs and non-negligible redshifts, z. Host contributions (from progenitor and/or host galaxy) could account for some of the DM, but large contributions might be thought to be disfavoured geometrically and in any event are suppressed by
a factor (1+z) in our frame of rest. Thus it is difficult not to conclude that the majority of the DM
for the majority of FRBs comes from the IGM, which is perhaps the most interesting point about
FRBs. If at such distances, but still detected as jansky-level sources with radio telescopes on Earth
they must then have high radio luminosities. Feeding this into a simple calculation of brightness
temperature implies that the emission is necessarily non-thermal with a high coherence factor. From our knowledge of pulsar emission, in particular the Crab pulsar’s so-called ‘giant
pulses’ which have comparable brightness temperatures, we might then conjecture that there
are strong magnetic fields at play and that the emitted radiation may be highly polarized. Basic
causality arguments tell us that, from the observed time duration of the bursts, the physical distance
scales of relevance are kilometres — in the most recent FRB discoveries features on ∼ 10-μs time
scales have been observed11 — implying that FRB progenitors likely involve compact objects,
and in particular neutron stars. The above deductions were mostly obvious from the first FRB
12 13–18 detection , but initial focus was quite rightly put onto confirming their astrophysical nature .
One of many things learnt from that work was the confidence that FRBs are bona fide astrophysical sources, and furthermore that they are numerous. Lower-limit estimates for the number of these events occurring are a few thousand each day .

See: https://arxiv.org/abs/1811.00899

Hartmann352
 
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