MSV-2035 Astronomy Document - Inside Design - FINAL - FINAL

Astronomy & Astrophysics 25 3 STATUS OF GLOBAL R&D EFFORTS The major science questions discussed in the previous section cover a wide range of scales (from the Sun to the entire universe). Several of these questions can, in practice, be addressed by a single observing facility with a suite of instruments. However, there are questions and aspects of a given science question that require using several facilities that enable observations of a class of objects at both the brighter and fainter ends and/or will provide a multi- wavelength perspective. Additionally, there are scientific questions that require large observing time, that are carried out using (i) dedicated survey facilities, (ii) “large observing ” with several tens of observing nights dedicated for a specific project proposed by a large community and (iii) network of observatories operating at different wavebands located in different part of the world and in space. The efforts of the global Astronomy & Astrophysics community in addressing some of the scientific questions listed in the previous section using existing and future large facilities and surveys in different wave bands are summarised in this Section. 3.1 UV-Optical-IR 3.1.1 GroundBased Facilities Any scientific question that requires optical and near-IR observations of faint and/or distant targets are at present addressed using ground based 8 to 10-meter class telescopes operating in the optical (0.4 -1.0 m) and near-IR ranges (i.e. 1-2 m). There are fifteen 10-meter class telescopes in the world, with capabilities to perform deep imaging, high resolution and/or multi-object spectroscopy in the optical and near-IR ranges, operational today. Few of them also possess capability to produce sharp images negating the effect of atmospheric blurring effects (using the “adaptive optics” technique). Some of themain accomplishments of these telescopes are summarized below. By determining the wavelengths of relevant spectral lines, the best possible constraints (one part per million) on the time variation of electromagnetic coupling constant ( α ) and electron-to-proton mass ratio ( µ ) are obtained. However, one needs an order of magnitude improvement in the sensitivity to be able to challenge the limits set by atomic clocks on earth. Astronomers are planning to achieve such a sensitivity using highly stable spectrographs andwavelength calibration using laser frequency combs. The 10-meter class telescopes have played a very important role in the field of early Universe and cosmology. Temperature measurements of the cosmic microwave background at different space and time have allowed us to confirm one of the main predictions of the Big Bang models. These telescopes also played an important role in proving the accelerated expansion of the Universe and confirming the Lambda cold dark matter (ɅCDM) paradigm. Measurements of Deuterium abundance and spatial fluctuations of matter in the Universe through spectroscopy of distant objects have allowed constraining the parameters governing the ɅCDMmodels and the power-spectrumof density fluctuations. These telescopes played an important role in constraining the epochs at which Hydrogen and Helium in the Universe were re-ionized. They also helped in detecting the nature of galaxies and the presence of supermassive black holes in the very early Universe. Deep imaging studies have allowed mapping the distribution of galaxies and quasars over cosmic time. Spectroscopic observations of bright distant objects have proved that most of the baryons in the Universe are in the diffuse intergalactic medium and programmes μ μ • • • MEGA SCIENCE VISION-2035