Royal Astronomical Society | 2015 May 14
The discovery of a ‘left-handed’ magnetic field that pervades the universe could help explain a long standing mystery – the absence of cosmic antimatter.
[img3="The new analysis looks for spiral patterns in the distribution of gamma rays within patches on the sky, with the highest energy gamma ray at the center of the spiral and the lower energy gamma rays further along the spiral. A helical magnetic field in the universe gives an excess of spirals of one handedness - and FGST data shows an excess of left-handed spirals. (Credit: Hiroyuki Tashiro)"]https://www.ras.org.uk/images/stories/p ... ma_dis.jpg[/img3][hr][/hr]Planets, stars, gas and dust are almost entirely made up of 'normal' matter of the kind we are familiar with on Earth. But theory predicts that there should be a similar amount of antimatter, like normal matter, but with the opposite charge. For example, an antielectron (called a positron) has the same mass as its conventional counterpart, but a positive rather than negative charge.
In 2001 Prof. Vachaspati published theoretical models to try to solve this puzzle, which predict that the entire universe is filled with helical (screw-like) magnetic fields. He and his team were inspired to search for evidence of these fields in data from the NASA Fermi Gamma ray Space Telescope (FGST).
FGST, launched in 2008, observes gamma rays (electromagnetic radiation with a shorter wavelength than X-rays) from very distant sources, such as the supermassive black holes found in many large galaxies. The gamma rays are sensitive to effect of the magnetic field they travel through on their long journey to the Earth. If the field is helical, it will imprint a spiral pattern on the distribution of gamma rays.
Vachaspati and his team see exactly this effect in the FGST data, allowing them to not only detect the magnetic field but also to measure its properties. The data shows not only a helical field, but also that there is an excess of left-handedness - a fundamental discovery that for the first time suggests the precise mechanism that led to the absence of antimatter. ...
Intergalactic magnetic field spectra from diffuse gamma rays - Wenlei Chen et al
- Monthly Notices of the RAS 450(4) 3371 (2015 Jun 11) DOI: 10.1093/mnras/stv308
arXiv.org > astro-ph > arXiv:1412.3171 > 10 Dec 2014
- Physical Review Letters 87(25) 251302 () DOI: 10.1103/PhysRevLett.87.251302
arXiv.org > astro-ph > arXiv:astro-ph/0101261 > 16 Jan 2001 (v1), 01 Nov 2001 (v3)