A new finding from the NASA/ESA Hubble Space Telescope

Hubble finds Universe may be expanding faster than expected

Astronomers have used Hubble to measure the distances to stars in nineteen galaxies more accurately than previously possible. They found that the Universe is currently expanding faster than the rate derived from measurements of the Universe shortly after the Big Bang. If confirmed, this apparent inconsistency may be an important clue to understanding three of the Universe’s most elusive components: dark matter, dark energy and neutrinos.

A team of astronomers, led by Nobel Laureate Adam Riess and using the NASA/ESA Hubble Space Telescope, have discovered that the Universe is expanding between five and nine percent faster than previously calculated. This is in clear discrepancy with the rate predicted from measurements of the infant Universe.

“This surprising finding may be an important clue to understanding those mysterious parts of the Universe that make up 95 percent of everything and don’t emit light, such as dark energy, dark matter, and dark radiation,” explains Adam Riess of the Space Telescope Science Institute and the Johns Hopkins University, both in Baltimore, USA.

One possible explanation for this unexpectedly fast expansion of the Universe is a new type of subatomic particle that may have changed the balance of energy in the early Universe, so called dark radiation.

The team made the discovery by refining the measurement of how fast the Universe is expanding, a value called the Hubble constant, to unprecedented accuracy, reducing the uncertainty to only 2.4 percent [1].

This new measurement presents a puzzle because it does not agree with the expansion rate found by looking at the moments shortly after the Big Bang. Measurements of the afterglow from the Big Bang from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck satellite mission yield smaller predictions for the Hubble constant.

Comparing the Universe’s expansion rate as calculated by WMAP and Planck (for the time after the Big Bang) and Hubble (for our modern Universe) is like building a bridge, Riess explains:

“You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right. But now the ends are not quite meeting in the middle and we want to know why.”

This refined determination of the Hubble constant was made possible by making precise measurements of the distances to both nearby and faraway galaxies using Hubble [2]. The improved distance measurements were made by streamlining and strengthening the cosmic distance ladder, which astronomers use to measure accurate distances to galaxies. The team compared these measured distances with the expansion of space as measured by the stretching of light from receding galaxies and these two values were then used to calculate the Hubble constant.

The team is continuing to use Hubble with the aim of reducing the uncertainty in the Hubble constant even further, their goal being to reach an uncertainty of just 1 percent. Current telescopes such as the European Space Agency’s Gaia satellite, and future telescopes such as the NASA/ESA/CSA James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT) could also help astronomers make better measurements of the expansion rate and lead to a better understanding of our Universe and the laws that govern it.

Notes

[1] Before Hubble was launched in 1990, estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to within 10 percent, accomplishing one of the telescope’s key goals. The new, improved Hubble constant value is 73.02 kilometres per second per Megaparsec (where one Megaparsec is equivalent to 3.26 million light-years).

[2] For the calibration of relatively short distances the team observed Cepheid variables. These are pulsating stars which fade and brighten at rates that are proportional to their true brightness and this property allows astronomers to determine their distances. The researchers calibrated the distances to the Cepheids using a basic geometrical technique called parallax. With Hubble’s sharp-eyed Wide Field Camera 3 (WFC3), they extended the parallax measurements further than previously possible, across the Milky Way galaxy. To get accurate distances to nearby galaxies, the team then looked for galaxies containing both Cepheids and Type Ia supernovae. Type Ia supernovae always have the same intrinsic brightness and are also bright enough to be seen at relatively large distances. By comparing the observed brightness of both types of stars in those nearby galaxies, the team could then accurately measure the true brightness of the supernova. Using this calibrated rung on the distance ladder the accurate distance to additional 300 type Ia supernovae in far-flung galaxies was calculated.

The European Southern Observatory (ESO) takes a step forward towards construction of the biggest telescope ever built:

ESO Signs Largest Ever Ground-based Astronomy Contract
for E-ELT Dome and Telescope Structure

At a ceremony in Garching bei München, Germany on 25 May 2016, ESO signed the contract with the ACe Consortium, consisting of Astaldi, Cimolai and the nominated sub-contractor EIE Group, for the construction of the dome and telescope structure of the European Extremely Large Telescope (E-ELT). This is the largest contract ever awarded by ESO and also the largest contract ever in ground-based astronomy. This occasion saw the unveiling of the construction design of the E-ELT. Construction of the dome and telescope structure will now commence.

The European Extremely Large Telescope (E-ELT), with a main mirror 39 metres in diameter, will be the largest optical/near-infrared telescope in the world: truly the world’s biggest eye on the sky. It will be constructed in northern Chile, on a site that has already been prepared.

The contract to build the telescope’s dome and structure was signed by ESO’s Director General, Tim de Zeeuw, the Chairman of Astaldi, Paolo Astaldi, and the President of Cimolai, Luigi Cimolai. ESO was delighted to welcome Italy’s Minister of Education, Universities and Research, H.E. Stefania Giannini, to the ceremony, which was also attended by the Italian Consul General in Munich, Renato Cianfarani, the ESO Council President, Patrick Roche, and the Italian ESO Council Delegates, Nicolò D’Amico (who is also President of INAF) and Matteo Pardo, Scientific Attaché at the Italian Embassy in Berlin. The President of EIE, Gianpietro Marchiori, and other guests and representatives of the consortium were also present.

The contract covers the design, manufacture, transport, construction, on-site assembly and verification of the dome and telescope structure. With an approximate value of 400 million euros, it is the largest contract ever awarded by ESO and the largest contract ever in ground-based astronomy.

A video describing the E-ELT project.

The E-ELT dome and telescope structure will take telescope engineering into new territory. The contract includes not only the enormous 85-metre-diameter rotating dome, with a total mass of around 5000 tonnes, but also the telescope mounting and tube structure, with a total moving mass of more than 3000 tonnes. Both of these structures are by far the largest ever built for an optical/infrared telescope and dwarf all existing ones. The dome is almost 80 metres high and its footprint is comparable in area to a football pitch.

The E-ELT is being built on Cerro Armazones, a 3000-metre peak about 20 kilometres from ESO’s Paranal Observatory. The access road and leveling of the summit have already been completed and work on the dome is expected to start on site in 2017.

Tim de Zeeuw, ESO’s Director General said:

“The E-ELT will produce discoveries that we simply cannot imagine today, and it will inspire people around the world to think about science, technology and our place in the Universe. Today’s signature is a key step towards delivering the E-ELT in 2024.”

Paolo Astaldi, Chairman of Astaldi added:

“This project is truly visionary, both in what it represents for the field of astronomy and for construction and engineering. Astaldi and our project partners, Cimolai and EIE Group, are extremely proud to have been selected by ESO through their call for tender to help make their vision a reality. Astaldi is renowned for delivering its best-in-class technical skills, quality construction and strong execution, and we will put the full force of our core strengths behind this project. It is with great excitement that I sign a contract of such astronomical ambition.”

Luigi Cimolai, President of Cimolai, said:

“We are honoured and grateful that our company has been given the opportunity to take part in this technically advanced astronomical challenge. The European Extremely Large Telescope will demand a high degree of quality in engineering and construction and I believe this will definitely contribute to further increase our ability to develop projects of greater and greater complexity.”

Many other aspects of the construction of the E-ELT are also moving forward rapidly. ESO has already signed agreements for the construction of the first-light instruments MICADO, HARMONI and METIS, as well as the MAORY adaptive optics system for the E-ELT. Contracts for the telescope’s huge secondary mirror will be signed in the near future.

The light-collecting area of the E-ELT will be bigger than all existing optical research telescopes combined and its adaptive optics system will provide images about 15 times sharper than those from the NASA/ESA Hubble Space Telescope at the same wavelength. It offers numerous possibilities for technology and engineering spin-offs, technology transfer and technology contracting. The new contract demonstrates that the E-ELT has the potential to be a powerhouse for economic development, offering contractors in ESO’s Member States an opportunity to lead major projects at an international level.