FRBs in the news again

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Random origins of FRBs in the universe. NRAO Outreach/Vimeo

Fast Radio Bursts (FRBs) are one of my favourite astronomical phenomena, because their cause or origin is still completely unknown. They are very short bursts of radio-frequency radiation, lasting just a few milliseconds, but of colossal intensity (the equivalent of 50 million times the sun’s energy in those few milliseconds). There have been only about 37 catalogued to date, all one-offs except FRB 121102.

FRB121102 is a “repeater” – a series of bursts were observed coming from the same source in 2012, then again on several days in 2015, and 15 more bursts during 30 minutes in 2017. The origin appears to be a galaxy about 2 billion light years away.

Although spinning black holes and neutron stars are possible candidate for generating the FRBs, there is no regularity of pulse in the transmissions as there is with spinning pulsars. One outside, but not discounted, possibility is that the source of the FRBs is some sort of extraterrestrial intelligent action – an attempt at communication or the utilisation of power for some purpose.

The new news is that researchers have re-analysed the data from August 26, 2017, when 21 bursts were detected, and they have found another 72 pulses by using AI – a convolutional neural network.

Link to Research paper

Link to Space.com article

Update 8th Jan 2019: A new Canadian Observatory called CHIME has reported finding another 13 FRBs including another repeater.

Update 14th February 2019: Observations reported today suggest that Superluminous Supernovae give rise to magnetars that then emit FRBs. More observations to follow.

Link to Scientific American article

Update 27th Jun 2019: Astronomers using the Australian Square Kilometre Array Pathfinder (ASKAP), a network of 36 radio telescopes, can now auto-detect and successfully triangulate to pinpoint the source of FRBs. Today they detailed one from the outskirts of a very different type of galaxy than the repeater mentioned above. This weakens the existing theory of the cause of FRBs.

Link to Space.com article

Update 15th August 2019: The Canadian Observatory called CHIME has reported detecting many more FRBs – importantly 8 more repeaters. Repeaters are especially important because they make it much easier to locate the exact source, and therefore to study that source with other instruments. Given the variation in time between repeats it could well be that all FRBs are repeaters – some are just more active than others. However the repeater bursts last a little longer than one-offs, and the repeaters all seem to exhibit a downward drift in frequency, with each burst getting lower. The source galaxies of the repeaters are now being determined by the direction from which the burst came, as well as the distance – which can be determined by the signal dispersion. Intriguingly, one of the repeaters is relatively close by. In addition the polarisation of the signal indicates how extreme was the magnetic environment at source. One of the new signals had very low polarisation so it is now known that not all FRBs originate near black-holes for example.

Science Alert Article

Update 12th Feb 2020: A new paper published in Nature has revealed that one of the Sources of repeating FRB’s (in a relatively nearby spiral galaxy) seems to be repeating on a 16-day cycle. This promises to be a massive clue in deciphering the mechanism behind FRBs, though such a mechanism is not immediately obvious. Most repeating patterns rely on rotations, but the rotation rates of neutron stars, pulsars and black holes tend to be many orders of magnitude faster than 16 days.

Live Science article

Research preprint

The Sexaquark and dark matter

Theoretical physicists crunching the maths have established that an exotic particle, called the sexaquark, consisting of six quarks – two ups, two downs and two stranges, could turn out to be very stable.

Familiar matter – protons and neutrons – are comprised of 3 quarks each and are stable. Particle accelerators have managed to produce 2-quark and 5-quark particles – but these are unstable and quickly decay. It just so happens that the sexaquark, if it has low mass, would be very stable. And low mass particles are not generally produced in colliders that operate at much higher energies, which is why it may not have been seen so far.

What is really exciting about this idea is that it is possible that during the early universe an abundance of these sexaquarks may have been produced, and being very stable they might still exist, not decaying, not interacting with normal matter or photons, except through gravity – in other words ‘dark matter’!

Live Science article

New idea for gravitational wave detector

The existing gravitational wave detectors, LIGO and Virgo, using long arms along which laser light travels to measure exquisitly small variations in length, are very expensive and complex devices. A new idea has been proposed to design a detector using the scattering effect on light photons of (still hypothetical) gravitons. This could potentially be a much cheaper, simpler device. If it worked it would also reveal a lot about gravitons and help to marry quantum physics and relativistic spacetime – an elusive but much pursued aim. It would also cast some light on th issue of whether gravitons are massless – moving at the speed of light, or have a small mass themselves and move slightly slower – the massive gravity theories. It would also have bearing on dark matter and dark energy.

Live Science article

Alzheimer’s – good, bad and more news

There is no still no scientific consensus on the causal mechanism of Alzheimer’s disease, or at least on the correct target for medicinal intervention – the four main contenders are:

(a) build-up of amyloid-beta fibrils

(b) build-up of tau protein tangles

(c) inflammation in the brain

(d) reaction to a virus infection

The Bad News: Last week the antibody drug “aducanumab” was withdrawn from clinical trials because of poor results – this was an anti-amyloid-beta drug. This follows other disappointing drugs aimed at amyloid-beta.

The Good News: However today there has been more positive news – a drug which has already been approved for clinical use against Hepatitis-D, called Lonafarnib, has been found to dramatically ameliorate the progress of dementia in a mouse model of the disease. The drug seems to block an enzyme (called farnesyltransferase) that facilitates the activity of the protein Rhes ultimately enhancing lysosome activity. Lysosomes are cellular waste-clearance systems that break down the toxic proteins, including tau. Research into this pathway and mechanism may open the door on further possible drugs.

Scientific American article

Update 29th May 2019:  Research published today seems to have established the mechanism by which the Herpes virus can facilitate Alzheimers. Essentially proteins from fluids within the body tend to stick to the virus surface, comprising what is termed a protein corona. It seems that there is enzymatic activity within that corona that facilitates the aggregation of amyloid plaques. It is suggested that this may not be the only causal factor leading to Alzheimers but certainly is capable of speeding up the disease process.

New Atlas article

Nature article

Update 16th Jan 2020: Research published today has shed some light on the possible mechanism leading to Alzheimers. It seems that even a little beta-amyloid will bind receptors fpr norepinephrine, a neuro-transmitter. This triggers the GSK3-beta enzyme which causes the tau tangles to become toxic, killing brain cells. This explains why the drug trials that aim to clear beta-amyloid have failed – there will always be a little left which is sufficient to trigger the critical link – GSK3-beta. The epinephrine receptor can be blocked by drugs such as idazoxan (which is already approved, but failed its clinical trials for depression treatment). Tests in mice have shown that tau build-up is indeed blocked by that drug. Independent work on blocking kinases has also implicated GSK3-beta. This holds great promise for a treatment at long last.

New force of nature?

A new publication in Physics suggests that there may be a fifth force of nature – joining gravity, electromagnetic and strong and weak nuclear forces.

The possibility first emerged when observations of the decay of an isotope of Beryllium showed an unexplained excess of electron/positron pairs diverging from each other at a preferred angle (instead of the angle varying with the energy of the excitation of the Beryllium nucleus). The results suggested a new particle, a force-carrying boson, with a distinctive mass of 17 MeV, albeit with a tiny lifespan.

Now, experiments with excited Helium nuclei have yielded the same result.

The particle is provisionally named X17.

The new particle interacts with neutrons, which has physicists excited that the particle may be linked with the gravitational interactions of dark matter.

Science Alert article

Cornell University arXiv

Measles virus wipes immunity to other pathogens

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Two new studies have clarified that an infection with the measles virus tends toward depleting the body of B-cells – those are the cells that produce antibodies against infections that the body has previously encountered. As a result, around half of the “immune memory” is eliminated, so that, after measles, the body is again vulnerable to infection by many of the pathogens that it had previously built resistance against.

The measles vaccine does not, of course, have that effect.

Mysterious Magnetic Pulses on Mars

compass

It was though that Mars had no significant global magnetic field, but NASA’s InSight Mars Lander has measured the crustal field to be 20x stronger than expected from orbital measurements. Moreover, the magnetic field seems to fluctuate in direction or strength at exactly midnight (that is Mars Lander’s midnight on Mars, not ours).
The Lander has also detected an unexpected electrically conductive layer about 2.5 miles thick, way below the surface (possibly an aquifer?). All this since its landing in November 2018.

National Geographic article