Archive for August 27, 2018

The Simons Observatory: Science Goals and Forecasts

Posted in The Universe and Stuff with tags , , on August 27, 2018 by telescoper

I haven’t been involved in this project, but several of my former colleagues at Cardiff have beenm and still are, so I know how much work has gone into this (especially by the amazing Erminia Calabrese), so I am happy to share this impressive work here. This long (54 pages) paper, which appeared on the arXiv last week, describes the latest step forward in ground-based cosmology using the cosmic microwave background. It shows just how rapid the onward march of instrumental technology continues to be.

The Simons Observatory Site, in Chile

It is likely that the Simons Observatory (based on a single 6m dish) will form part of the next generation CMB experiment known currently as CMB-S4.

You can download the paper in full from the arXiv here.

The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes (SATs) and one large-aperture 6-m telescope (LAT), with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The SATs will target the largest angular scales observable from Chile, mapping ~10% of the sky to a white noise level of 2 μK-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of σ(r)=0.003. The LAT will map ~40% of the sky at arcminute angular resolution to an expected white noise level of 6 μK-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the LSST sky region and partially with DESI. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel’dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.

Golf and other Hazards

Posted in History, Maynooth, Sport with tags , , , , , on August 27, 2018 by telescoper

Back in the office with a few minutes to go before a meeting starts I thought I’d give a little insight into life in the throbbing metropolis that is Maynooth, County Kildare. This week sees the start of the World Amateur Team Golf Championships, which is being held at Carton House (above) which is a short walk from downtown Maynooth. Some of the competitors will be staying on Maynooth University campus for the duration, which will no doubt provide welcome revenue.

Now the game of golf is obviously of no conceivable interest to anyone, but the venue – Carton House – is quite fascinating. The current house was built on the Carton Estate in the 18th Century to accommodate the Earl of Kildare, when their fortunes had slowly recovered after Thomas Fitzgerald (`Silken Thomas’) the 10th Earl of Kildare was executed, along with several others of the Fitzgerald family, by Henry VIII for plotting a rebellion against the English. If you have been paying attention you will know that it was the Fitzgeralds who built the stone castle in Maynooth that was destroyed in the 16th Century. Carton House is at the other end of town, and is approached by a very pleasant tree-lined avenue. The extensive grounds are also surrounded by a wall. The latter-day Fitzgeralds obviously wanted to keep the hoi polloi at arm’s length.

Anyway, to cut a long story short, Carton House fell into disrepair in the second half of the 20th Century and was eventually sold off and turned into a hotel and spa resort, with two golf courses.

In the meantime, among many other things, Carton House and it its grounds were used as one of the locations for Stanley Kubrick’s (1975) film Barry Lyndon. That was of course before the beautiful landscaped gardens were destroyed and turned into golf courses. I went for a pleasant walk in the grounds earlier this summer, during the heatwave, but the path runs alongside a small lake beside one of the fairways where a group of people were openly committing acts of golf. A not-very-competent member of this group sent several balls into the water before finally managing to hit dry land with a tee shot. For a while I wished I’d brought a tin hat with me.