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April 1, 2023



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The GTC and the Cosmology


Every year the Instituto de Astrofísica de Canarias (IAC) hosts a Canary Islands Winter School of Astrophysics. For two weeks, PhD students and recently graduated Doctors of Astrophysics focus on a hot topic in astronomy with a group of eminent experts.

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    This year, the school brought together eight experts in Cosmic Microwave Background Radiation, the fossilised record of the Big Bang that shows us what the infant universe was like before the birth of stars. They areSabino Matarrese, of the University of Padua (Italy), Wayne Hu, of the University of Chicago (USA), Bruce Partridge, of Haverford College (USA), Matthias Bartelmann, of the ITA (Institute of Theoretical Astrophysics), at Heidelberg (Germany), Rod D. Davies, of Manchester University (United Kingdom), Licia Verde, of Pennsylvania University (USA), Enrique Martí­nez González, of the Cantabria Institute of Physics (IFCA), and Malcolm Longair, of Cambridge University, in the United Kingdom.

    We wanted to find out what large telescopes like the Gran Telescopio CANARIAS (GTC) can contribute to disciplines like Cosmology, which is concerned with the origins, evolution and content of the universe. This is what they told us.

    Click here for further information and videos of the Winter School:


    Licia Verde

    Cosmology asks questions about the universe: what are its origins, how did it evolve and what does it contain? This becomes much easier if we can look back through the different stages of the universe - like getting to know more about a person by travelling back in time through the pages of a photo album until we see them as a child. Very large telescopes are needed to look back at the history of the Universe, and the ten metre one in the Canaries are the largest optical telescope in existence.

    Bruce Partridge

    The problem with Cosmology is that you are often interested in the Early Universe. And that, by definition, means that you need to look out to large distances. If you are looking out to large distances, you also need to be looking at objects that are intrinsically going to be very faint, they are so far away. So, in order to see these objects and to study their properties, what you want is as larger area to collect the light from them as possible. Think for a moment about collecting rain, you get a lot more rain if you have a large collecting area.

    Sabino Matarresse

    Big telescopes are a crucial ingredient of the present state of Cosmology. We are used to say that we live in a so called "Precision Era" of Cosmology, which means that now we know the ingredients of the Universe, we know the properties of the Universe with a very high precision, and we have that high precision precisely because of this telescopes, on those that we have yet and on those that we are going to have in the near future.

    Bruce Partridge

    The features of the big telescopes now are both that they get a lot of light and also that they are equipped with very efficient detectors and that the light that they capture is no wasted... so both of those features go together and both are going to be done here.

    Wayne Hu

    Astronomy needs big telescopes, why we need that is: we are looking at really faint objects, in the very distant Universe. We need to collect a lot of light, and so a ten meter diameter is huge and we need that largeness to collect the light and see these distant objects, see things about their physical aspects, like their spectra, that is how the light depends on frequency, and the next generation of instruments are ten meters and above up to what people are planning to build even larger ones in the future, but ten meters is state of the art right now.

    Rod Davies.

    The big telescopes, like your one on La Palma, have a major contribution now to make the understanding; for example the state of the Universe, the very size is depending upon our knowledge of some of the most distant galaxies that we have, and the big telescopes (and the new technologies that go with them) give you the opportunity to see in detail and measuring extremely faint objects.

    Matthias Bartelmann

    They will extend our arising, they will allow us to see further back in time and therefore will allow us to probe the evolution of the Universe over a larger range; that is one effect that it has, and the other effect is that you can see things better, things that are closer to us, so I think a more detailed knowledge of objects already known and the extension of our arising to those objects that we have not seen before are the too main contributions of big telescopes.

    Enrique Martinez

    The greatest challenges facing Cosmology today are finding out what dark matter is made of and understanding the nature of dark energy; and investigating galaxy formation - because we still do not know by what mechanisms they form and spread out. A telescope as large and as powerful as the GTC will naturally be able to provide us wAith a great deal of information about this.

    Malcolm Longair

    Cosmology is a statistical science, we've only got one Universe to look at, but we must be able to understand in great detail things we can observe within our observable Universe, so the new large telescope is one of a number of facilities which are ideal for carrying out that task. So it is part of this tremendous endeavour that is going worldwide to really put more physics into Cosmology so that we can really build better models for how our Universe came about, how galaxies formed, how stars, how planets, and how we came about. It is all part of a large international endeavour.

    Natalia R. Zelman

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