I have a strong feeling the first lecture I ever heard on gamma-ray bursts was by Nial Tanvir, now at the University of Leicester. I remember him explaining how in the early days of the field, astronomers studying GRBs were among the first people to get mobile phones as they needed to be told when a burst was detected. In the last few years, the advent of Swift has revolutionized the field, and I caught up with Nial in a rather echoing corridor to find out the latest news.

Gravitational lensing is one of nature’s more useful gifts to astronomers. At a very simple level (the kind I can reach given what time I got up this morning) the path of light is bent by the presence of mass, as best seen in galaxy clusters like this one.  The arcs are distant galaxies whose image has been distorted.

Galaxy Cluster Abell 1689 as seen by the Hubble Space Telescope.

Of course, this is an extreme example, but by studying the shear - a small distortion of the shape of many galaxies - it’s possible to reconstruct the distribution of the mass by which the light has passed. In recent years, this has been done for large chunks of the Universe, producing a rather blobby map of the distribution of dark matter.  

To improve on these results, Rachel McInnes of the University of Edinburgh reckons we need to take advantage of new surveys like Pan-Starrs (more on which later in the week). To do that and include many many more galaxies in the analysis she needs to automate lots of the tasks currently carried out by humans, such as cleaning up the images to avoid confusing the program; work’s underway, and the techniques are being tested on another, smaller survey while we build up to Pan-Starrs at the end of the year.

Everyone wants a Eureka moment in their scientific career, whether it’s jumping out of a bath or seeing the first light from a supernova. The truth, though, is that they’re very very rare, but in today’s first plenary talk we got a glimpse of the moment when one of the most important discoveries of the last decade or so took place. Brian Schmidt, from the Australian National University, was part of one of the two teams that independently discovered that the Universe was accelerating, rather than slowing down under the influence of gravity as (almost) everyone expected. He showed the audience the page from the lab notebook belonging to Adam Reiss, who was the first to realise what their observations showed; the underlined conclusion was that without acceleration, the results produced a negative mass for the Universe. Thus the assumption was wrong, and thus acceleration. So that’s it - Adam at least had his Eureka moment (and was at least excited enough to underline it!). Except that for the rest of the team, despite being involved in such a remarkable discovery, there was no Eureka. Brian reported his instantaneous reaction was that the result must be wrong…for them this great discovery was not an eureka, but a slow dawning that their result might just be correct… Dual post : Both Will and I are obviously in the same lecture. Here’s his take

Good morning from Belfast! I’m sitting inside the main lecture theatre here at Queen’s University listening to the two early morning plenary session talks. Dr Brian Schmidt from the Australian National University is first up and is giving a great talk on ‘Measuring cosmic acceleration’. It’s a fascinating story which begins, in some sense at least, in the mid to late nineties when astronomers found evidence that the rate at which the Universe was expanding is accelerating.

They had been studying cosmic events called Type Ia supernovae. These are violent thermonuclear events which can appear up to 100 times brighter than Type II supernovae in the night sky and “5 billion times brighter than our Sun”. Astronomers use this particular brand of supernovae as what they call a ‘standard candle’; essentially a cosmic distance marker*. That’s because the mechanisms and processes that form them (currently thought to be the dumping of matter (accretion) onto a white dwarf by a companion star) are fairly well understood. Since they are understood and are extremely bright, for a given distance, astronomers know how bright they should be; thus making them good standard candles.

Today much of what we know about dark energy and the expansion of the Universe has come from observations of distant Type Ia supernovae and the Cosmic Microwave Background. According to Dr Schmidt the whole discussion around the accelerating Universe has developed tremendously in the last ten years. That is primarily because of the discovery of the presence (or really the inference) of dark energy - a component of matter, in the Universe, which appears to be causing the rate of expansion to speed up.

Dr Schmidt has a website here and a great web-presentation on ‘The Accelerating Universe - an explanation for the interested non-scientist’ here.

*It’s worth noting, says Dr Schmidt, that not all Type Ia supernovae are the identical. It’s thanks to work done by several astronomers investigating the nature of different Type Ia events (and their light curves) that we can still use them as good standard candles.

Above: The result of a Type Ia supernova? - Tycho’s Supernova
Credit: NASA/ESA, CXO and P. Ruiz-Lapuente (University of Barcelona)

It must only be UK astronomers who associate NAM with meeting old friends and catching up on science rather than old war movies and Apocalypse Now, but at least this year’s National Astronomy Meeting is starting with a bang. An new image released by a team from our hosts, Queen’s University Belfast, shows a supernova in the galaxy NGC 2397.

The picture includes an image of supernova 2006bc, an explosion that marked the death of a massive star. Unusually, the image includes the supernova while it is still on the rapid climb to maximum brightness; capturing supernovae early is crucial to improving our understanding of these dramatic events. The work of the team at QUB focuses on combing through images taken before the explosion in order to determine the nature of the stars which will end their lives so dramatically. Their hard work seems to show that a stellar mass of just seven times that of the Sun is sufficient to produce such an explosion, but no very massive stars have been identified as supernova precursors. That suggests that these massive stars might be directly collapsing to black holes - an intriguing possibility.