Archive for European Southern Observatory

Gas Filaments in the Cosmic Web

Posted in Astrohype, The Universe and Stuff with tags , , , , , on October 4, 2019 by telescoper

I saw that there’s a new paper that has just been published in the journal Science by Umehata et al with the title Gas filaments of the cosmic web located around active galaxies in a protocluster. In case you run into a paywall at Science, you may of course, find the paper on the arXiv here.

The abstract reads:

Cosmological simulations predict the Universe contains a network of intergalactic gas filaments, within which galaxies form and evolve. However, the faintness of any emission from these filaments has limited tests of this prediction. We report the detection of rest-frame ultraviolet Lyman-alpha radiation from multiple filaments extending more than one megaparsec between galaxies within the SSA 22 proto-cluster at a redshift of 3.1. Intense star formation and supermassive black-hole activity is occurring within the galaxies embedded in these structures, which are the likely sources of the elevated ionizing radiation powering the observed Lyman-alpha emission. Our observations map the gas in filamentary structures of the type thought to fuel the growth of galaxies and black holes in massive proto-clusters.

The existence of a complex cosmic web of filaments and voids has been known about for some time as it is revealed on large scales by the distribution of galaxies through redshift surveys:

You can see all my posts agged with `Cosmic Web’ here. There are also good theoretical reasons (besides numerical simulations) for believing this is what the large-scale distribution of matter should look like. Roughly speaking, dense knots of matter lie at the vertices of a three-dimensional pattern traced out by one-dimensional structures.

We have also known for some time, however, that there is more going on in cosmic structure than is revealed by light from stars in galaxies. In particular the way gas flows along the filaments into the knots plays an important role in galaxy and cluster formation. This paper reveals the distribution of gas around a giant cluster that has formed at such a node using observations made using the European Southern Observatory’s MUSE instrument.

Here’s a pretty picture:

I found out about this paper from a news piece in the Guardian with the title Scientists observe mysterious cosmic web directly for first time. That’s sufficiently misleading for me to cross-file the paper under `Astrohype’ because, as I explained above, we have been observing the cosmic web for decades. It is however only just becoming possible to observe the diffuse gas rather than having to join the dots between the galaxies so it is an exciting result. My complaint, I suppose, is that the word `directly’ is doing a lot of heavy lifting in the title!

Advertisements

Who uses LinkedIn?

Posted in Science Politics, The Universe and Stuff with tags , , , , on September 5, 2019 by telescoper

We had a talk at INAM2019 yesterday about the Astronomical Science Group of Ireland which is about to be re-launched with a new website. One of the main reasons for doing this is that Ireland recently joined the European Southern Observatory and in order to capitalize on its involvement it is important to persuade the Irish government to invest in the resources needed (especially postdocs, etc) to do as much science as possible using ESO facilities. At the moment there isn’t a very well organized lobby for astronomy in Ireland.

One of the suggestions made yesterday was that astronomers in Ireland should join LinkedIn in order to raise their profile individually and collectively.

I am not, and have never been, on LinkedIn and this is the first time I’ve ever even thought of joining it (though I do from time to time receive emails from people I don’t know asking me to). I’ve always thought it was for more businessy types. I don’t know of any astronomers (or scientists generally) who use it either, but that may be just because I’m not on it and wouldn’t know either way.

I just thought therefore, that I might invite any readers of this blog – whether astronomers or not – if they use LinkedIn to please comment on its usefulness or otherwise using the box below. Please also comment on whether you think it would help astronomers in Ireland organize in the manner envisaged.

Banging the drum for ESO

Posted in Maynooth, The Universe and Stuff with tags , , , on February 6, 2019 by telescoper

It was a pleasure to welcome Rob Ivison, Director of Science at the European Southern Observatory (ESO) , to Maynooth this afternoon for a colloquium.

I was on my best behaviour introducing his talk and even refrained from pointing out that his native Lancashire is actually in the Midlands.

Ireland became a full member of ESO earlier this year and Rob has been touring Ireland giving talks to encourage Irish astronomers to make the most of the many opportunities membership presents. Having already visited Cork and Galway he passed through Maynooth today before ending up in Dublin tomorrow.

It was an enjoyable and impressive talk and very nice to chat with Rob afterwards over dinner.

Bon voyage to Rob and thanks for the visit!

Newsflash: Ireland and ESO

Posted in Science Politics, The Universe and Stuff with tags , , on September 26, 2018 by telescoper

Some good news was waiting for me when I got back to the office after my lecture just now, namely that Astronomy in Ireland will shortly receive an enormous boost, as the Republic has joined the European Southern Observatory (ESO).

For those of you not in the know, ESO is an intergovernmental astronomy organisation and is the world’s most productive astronomical observatory. Founded in 1962, its headquarters are in Garching (near Munich, Germany), and it currently has 15 member states. On October 1st, Ireland will become the 16th. Its main work is conducted using a variety of large optical and radio telescopes which are all located in the southern hemisphere, notably at Paranal in Chile.

ESO’s VLT telescopes at Paranal (in the Andes Mountains).

The official press release includes the following:

We are delighted to welcome Ireland as the newest member of our organisation” stated ESO’s Director General, Xavier Barcons. “Ireland’s mature and thriving astronomical community will add to the broad variety of expertise in the ESO Member States, strengthening ESO’s position at the forefront of global astronomy. Irish astronomers will gain access to a suite of the world’s most advanced ground-based astronomical telescopes and will have the opportunity to be part of the construction of the next generation of ESO instruments in partnership with other ESO Member States. We are also very much looking forward to working with Irish industrial partners to build and operate ESO’s state-of-the-art telescopes.

It was probably the industrial opportunities afforded by ESO membership that persuaded the Irish government to stump up the subscription fee, but this decision is also extremely positive news for the relatively small but vibrant community in Ireland working on observational astronomy which I’m sure will make the most of the chance to do ever more exciting research using these facilities.

Gravitational Redshift around the Black Hole at the Centre of the Milky Way

Posted in The Universe and Stuff with tags , , , , , , on July 26, 2018 by telescoper

I’ve just been catching up on the arXiv, and found this very exciting paper by the GRAVITY collaboration (see herefor background on the relevant instrumentation). The abstract of the new paper reads:

The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A* is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU, ~1400 Schwarzschild radii, the star has an orbital speed of ~7650 km/s, such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z ~ 200 km/s / c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 +/- 0.09 (stat) +\- 0.15 (sys). The S2 data are inconsistent with pure Newtonian dynamics.

Note the sentence beginning `Over the past 26 years…’!. Anyway, this remarkable study seems to have demonstrated that, although the star S2 has a perihelion over a thousand times the Schwarzschild radius of the central black hole, the extremely accurate measurements demonstrate departures from Newtonian gravity.

The European Southern Observatory has called a press conference at 14.00 CEST (13.00 in Ireland and UK) today to discuss this result.

E-ELT: The Big Picture

Posted in Science Politics, The Universe and Stuff with tags , , , on March 4, 2013 by telescoper

Some astronomy news that made a bit of a splash over the weekend was the announcement that the UK is to invest £88 million in the European Extremely Large Telescope. This amount is to be spread over 10 years, so isn’t quite as astronomical as it sounds, but in any case it is only the UK’s contribution to a project that involves large contributions from the other countries involved in the European Southern Observatory. The UK announcement isn’t the end of the story, in fact, as not all the money needed to make the project work is yet in place.

This is all good news, especially because not long ago it seemed quite likely that the UK would have to make a choice between the E-ELT and the Square Kilometre Array. Now it looks like we’re going to be involved in both of the world’s leading ground-based observational facilities. There is a price to be paid, of course. In order to accommodate these projects within the flat-cash budget of the Science and Technology Facilities Council, difficult choices had to be made, and some things have to go. Not everyone will be happy about the outcome, but Big Science requires Big Decisions.

Anyway, it was nice to see the Observer run a piece about this story, although I was a bit baffled by the implication of the caption going with the picture used to illustrate the story:

The European Extremely Large Telescope will study the Magellanic Cloud.

I’ll avoid asking “which Magellanic Cloud (Large or Small)?” and just point out that E-ELT will study a lot more than either or both! Still, people are more likely to read web articles if they include images, so I’ll end this piece with an appropriate one.

Random Astronomical Image

Random Astronomical Image

Astronomy’s Next Big Thing

Posted in Science Politics, The Universe and Stuff with tags , , , , on June 12, 2012 by telescoper

I woke up this morning to hear an item about astronomy on the 7 o’clock news on BBC Radio 3. That doesn’t happen very often so I thought I’d follow it up with a short post before I head off to work.

The news item I heard followed up an announcement yesterday that the governing Council of the European Southern Observatory (ESO) had  approved the European Extremely Large Telescope (E-ELT) programme – which is to produce what will be the world’s largest ground-based optical telescope. Extremely Large is putting in mildly, of course. Its main mirror will be a colossal 39 metres in diameter (with a collecting area of almost a thousand square metres) and will have to made in bits with a sophisticated adaptive optics system to ensure that it can counter the effects of the Earth’s atmosphere and the limitations  of its own structure to  reach a phenomenal angular resolution of 0.001 arc seconds.

For more details on the telescope, see the official website here or the wikipedia article here, where you can also read more about the science to be done with E-ELT.

This telescope has been in planning for many years, of course. In fact, it began as an even more ambitious concept, a 100-metre diameter monster which I used to call the FLT. Over the years, however, for a mixture of technical and financial reasons, this was progressively de-scoped.

Yesterday’s announcement doesn’t mean that work will start immediately on building the E-ELT. That won’t happen until sufficient funding is secured and in the case of some countries, governmental approval obtained. Recent decisions by the UK Science and Technology Facilities Council to close down telescopes in Hawaii clearly anticipated the need to make some headroom in future budgets to enable this to happen. The best-case scenario is probably for E-ELT to take a decade or so to complete.

Of course the concentration of funding in ever and ever larger international facilities – such as E-ELT and the Square Kilometre Array – does create tensions within the UK astronomical community. Many scientists do excellent work with relatively small facilities, including those about to be closed down to make room for E-ELT. In the near future, the only ground-based optical facilities to which UK astronomers will have access will be operated by the European Southern Observatory. With fewer but larger (and more expensive) facilities operated by international agencies carrying out projects run by vast consortia, observational astronomy is definitely going the way of particle physics…

The problem  comes when the Next Big Thing  is too big to be built.  We might have already seen X-ray astronomy bubble burst in this way. To quote my learned friend Andy Lawrence:

Fundamentally, the problem is that X-ray astronomy has hit the funding wall. Everything gets inexorably bigger and more ambitious. Eventually its all or nothing… so when the answer is nothing … ah.

What will come after the Large Hadron Collider, or the E-ELT?  Is Big Science about to get too big?