Final Activity Report Summary - ANGLES (Astrophysics Network for Galaxy Lensing Studies (ANGLES))
Understanding how the Universe evolved from almost complete uniformity to the present state in which there is a rich assortment of planets, stars, galaxies and clusters of galaxies is one of the most exciting quests of modern science. It grabs the attention of the public at large and has a strong positive influence in attracting young people into the physical sciences.
The ANGLES project focussed on the properties of compact structures in the Universe ranging in mass from clusters of galaxies through galaxies themselves, to stars within galaxies and, finally, to planets around stars. The unifying theme was the use of the gravitational lens phenomenon as a tool to study mass distributions. The great thing about gravitational lensing was that the effects were the same regardless if the matter that bent the light was the normal stuff that we and our surroundings were made of or mysterious dark matter.
A remarkable achievement was the detection of planets outside our solar system by their lensing effects on stars, and ANGLES people, such as the experienced researcher (ER) Wyrzykowski, Rattenbury and Mao, played a significant role. When a star passed in front of another, the lensing effect magnified the distant star producing a dramatic brightening which lasted for weeks. If the foreground star had planets they could also produce additional magnification; however this only lasted for hours. Millions of stars were monitored every night to look for these rare events. Compared to other planet search techniques lensing could detect Earth-like planets in the so-called habitable zone. It located them so we could be confident that there were plenty of planets like our own which could potentially host life.
At the other extreme of scales Li, from Shanghai, and Mao, from the Jodrell Bank Centre for Astrophysics (JBO), counted the giant arcs produced by the lensing action of clusters of galaxies. They concluded that the low value for the cosmological parameter sigma-8 favoured by the initial data released by the cosmic microwave background satellite WMAP was not supported by the arc statistics.
The way in which matter, both luminous and dark, was distributed in galaxies figured large in the network activities. Work led by the group in the University of California (UC) Davis indicated that many lens galaxies were members of small groups. During related work with the Bonn group they identified a faint companion galaxy in B2045+265 that explained why the image positions and flux densities were hitherto difficult to fit.
The network exploited the unique ability of lensing to measure the properties of dust distant galaxies. Astronomers perception of the whole visible universe was literally coloured by the amount of dust they viewed it through. Surprisingly, dust played a vital role in enabling stars and planets to form. The Copenhagen group reported the results of their studies of the extinction properties of ten lensing galaxies using the very large telescope (VLT).
Gravitational lensing was a versatile tool. By measuring the difference in time it took for light to come from the original object by the separate light paths which led to the production of multiple images, one measured the real physical scale of the lensing geometry. Hence one was able to make an independent determination of another cosmological parameter, the Hubble constant. The lens system B0218+357 was utilised for doing this by an ANGLES team.
Early-stage researcher (ESR) More and ER McKean detected maser molecular line emission in a lens system. A paper reporting this discovery, which represented the most distant and most luminous water vapour maser ever found, was submitted to Nature.
Training and transfer of knowledge was central to the network activities. Network researchers were offered more than 80 hours of lectures and training by world experts in a series of five schools. Four of the nine ESRs had already obtained PhDs by the time of the project completion. Among them, two had moved on to postdoctoral positions in prestigious United States universities. Finally, one of the ERs was awarded an Emmy Noether fellowship.
The ANGLES project focussed on the properties of compact structures in the Universe ranging in mass from clusters of galaxies through galaxies themselves, to stars within galaxies and, finally, to planets around stars. The unifying theme was the use of the gravitational lens phenomenon as a tool to study mass distributions. The great thing about gravitational lensing was that the effects were the same regardless if the matter that bent the light was the normal stuff that we and our surroundings were made of or mysterious dark matter.
A remarkable achievement was the detection of planets outside our solar system by their lensing effects on stars, and ANGLES people, such as the experienced researcher (ER) Wyrzykowski, Rattenbury and Mao, played a significant role. When a star passed in front of another, the lensing effect magnified the distant star producing a dramatic brightening which lasted for weeks. If the foreground star had planets they could also produce additional magnification; however this only lasted for hours. Millions of stars were monitored every night to look for these rare events. Compared to other planet search techniques lensing could detect Earth-like planets in the so-called habitable zone. It located them so we could be confident that there were plenty of planets like our own which could potentially host life.
At the other extreme of scales Li, from Shanghai, and Mao, from the Jodrell Bank Centre for Astrophysics (JBO), counted the giant arcs produced by the lensing action of clusters of galaxies. They concluded that the low value for the cosmological parameter sigma-8 favoured by the initial data released by the cosmic microwave background satellite WMAP was not supported by the arc statistics.
The way in which matter, both luminous and dark, was distributed in galaxies figured large in the network activities. Work led by the group in the University of California (UC) Davis indicated that many lens galaxies were members of small groups. During related work with the Bonn group they identified a faint companion galaxy in B2045+265 that explained why the image positions and flux densities were hitherto difficult to fit.
The network exploited the unique ability of lensing to measure the properties of dust distant galaxies. Astronomers perception of the whole visible universe was literally coloured by the amount of dust they viewed it through. Surprisingly, dust played a vital role in enabling stars and planets to form. The Copenhagen group reported the results of their studies of the extinction properties of ten lensing galaxies using the very large telescope (VLT).
Gravitational lensing was a versatile tool. By measuring the difference in time it took for light to come from the original object by the separate light paths which led to the production of multiple images, one measured the real physical scale of the lensing geometry. Hence one was able to make an independent determination of another cosmological parameter, the Hubble constant. The lens system B0218+357 was utilised for doing this by an ANGLES team.
Early-stage researcher (ESR) More and ER McKean detected maser molecular line emission in a lens system. A paper reporting this discovery, which represented the most distant and most luminous water vapour maser ever found, was submitted to Nature.
Training and transfer of knowledge was central to the network activities. Network researchers were offered more than 80 hours of lectures and training by world experts in a series of five schools. Four of the nine ESRs had already obtained PhDs by the time of the project completion. Among them, two had moved on to postdoctoral positions in prestigious United States universities. Finally, one of the ERs was awarded an Emmy Noether fellowship.