Scientists working with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) observatory report the discovery of the most distant gamma-ray source ever observed at very high energies, thanks to the “replay” of an enormous flare by a galactic gravitational lens as foreseen by Einstein’s General Relativity.

In a study published last Friday in the journal Astronomy & Astrophysics, scientists of the international collaboration of the MAGIC telescopes (Major Atmospheric Gamma Imaging Cherenkov Telescope), located at the Roque de los Muchachos Observatory, in Garafía (La Palma), and among which are researchers of the Institute of Cosmos Sciences (ICCUB), have announced the discovery of gamma-ray emission more distant than any previous detection. The discovery was made possible by the gravitational lensing caused by a massive galaxy between the quasar and Earth, that “repeated” the light produced by the source.

According to Einstein’s General Relativity, light is deflected passing close to a large mass. To a distant observer the mass focuses light like a giant lens. The result is a much brighter, although distorted, image of the source and a chance to see distant objects that might otherwise be far too faint to detect. And just like a lens, light can pass through the lens with slightly different path lengths. On cosmic scales, this means photons — parcels of light — traveling along different lines of sight arrive at slightly different times. If, in addition, the source is variable, this is “imprinted” on the light with a time delay relative to a fixed first arrival. And this should not depend on the energy of the photons, according to the theory. That makes such observations especially important.

QSO B0218+357 harbors a supermassive black hole in a galaxy located halfway across the Universe from Earth. Over 7 billion years ago a gigantic explosion occurred in this object, which led to the emission of an intense flare of gamma rays, which is the highest-energy form of light. In its long journey toward Earth, these photons passed in the vicinity of a foreground — still distant — galaxy, B0218+357G, over one billion years later. In passing and being deflected, those photons traveling along the shorter path finally arrived at Earth on July 14th, 2014 and were observed by the Large Area Telescope on board the orbiting Fermi satellite, which scans the entire sky every 3 hours. The detection of this gamma-ray outburst alerted the astronomical community, and many telescopes worldwide were immediately pointed at QSO B0218+357 to learn more from this distant cosmic explosion. Researchers operating the MAGIC telescopes, located on La Palma in the Canary Islands, became excited about the possible observation of this object in very-high-energy gamma rays. These could provide the most extreme perspective of this outburst, but, unfortunately, at that time there was full moon in La Palma, which prevented the operation of the MAGIC telescopes. The MAGIC telescopes measure very-high-energy gamma rays, which are a thousand times more energetic than those measured by Fermi, and a hundred billion times more energetic than any light we see from our Sun.

From the earlier measurements of this object in 2012 by Fermi and by radio telescopes the scientists knew that photons arriving along the longer path should arrive about 11 days later. In consequence, a powerfull very-high-energy gamma-rays was detected by the MAGIC telescopes as they were pointing QSO B0218+357 those 11 days later. This object has become the farthest ever detected in this range of energy. These very-high-energy gamma-rays from any distant source have a high chance to interact with the numerous low-energy photons emitted by galaxies and stars, being lost in the process. With this observation, MAGIC has doubled the previously known visibility range of the Universe in very-high-energy gamma rays. Observation of the delayed signal from QSO B0218+357 by MAGIC showed for the first time that these very energetic photons are also deflected in agreement with General Relativity, a result that is both striking and potentially profound. The signal arriving at the predicted time may rule out some theories of the structure of the vacuum. That awaits further analysis. For the moment, this observation demonstrates a new capability of the very-high-energy gamma-ray observatories and highlights what awaits the next generation of such telescopes, the Cherenkov Telescope Array (CTA) project.

MAGIC telescopes

MAGIC is a ground-based gamma-ray instrument located on the Canary island of La Palma, Spain. The system of two 17m diameter Cherenkov telescopes is currently one of the three major imaging atmospheric Cherenkov instruments in the world. It is designed to detect gamma rays tens of billions to tens of trillions times more energetic than visible light. MAGIC has been built with the joint efforts of a largely European collaboration that includes about 160 researchers from Germany, Spain, Italy, Switzerland, Poland, Finland, Bulgaria, Croatia, India and Japan.

The High Energy Astrophysics group at the ICCUB are members of the MAGIC collaboration and have participated in this discovery.

More information:

Article: “Detection of very high energy gamma-ray emission from the gravitationally lensed blazar QSO B0218+357 with the MAGIC telescopes”, by M. L. Ahnen et al. A&A 595, A98, 2016.
http://www.aanda.org/articles/aa/abs/2016/11/aa29461-16/aa29461-16.html

MAGIC website: https://wwwmagic.mpp.mpg.de/

Exomars page on Serviastro

This first cartography of Gaia mission, in which there is the participation of a team from the Institute of Cosmos Sciences (IEEC-UB), shows the position of 1.142.69.769 sources, most of them stars of the Milky Way and neighboring galaxies. Gaia also observed the position of extragalactic objects such as quasars and distant galaxies. In addition, it shows in detail the tridimensional position for more than two million stars. This is a giant step to create the map of the universe. The results have been published in the journal Astronomy & Astrophysics.

The most precise map of the Universe

The map has an average precision of 10 mili-arc-seconds, which is similar to the precision of the Hubble Telescope (but this one only covers a small area of the space). Actually, Hubble will use Gaia’s map as a basic cartography to prepare and analyze its observations. Another of the map’s applications is to improve the predictions on the observation of astronomical phenomena, such as eclipses of stars by plants or the Solar System asteroids.

Apart from this big position map, this publication shares distances and movements related to more than two million stars in our closest area (hundreds of light-years) with a precision without precedents which allow astrophysics to analyze the solar environment in three dimensions, opening new windows to stellar physics and the mechanisms of creation and evolution of the stars.

The map shows, for example, the two Magellanic clouds (bottom right side), one of the closest galaxies to the Milky Way. At the left side of the Mini Magellanic Cloud there is a shiny small spot. It is a globular cluster created by hundreds of thousands of stars which have been and still are measured by Gaia.

Other distant galaxies observed by Gaia are Andromeda and M33, located at the bottom left of the Milky Way. Gaia, with a non-precedent precision, is measuring the position of the stars that build these stellar systems, placed at more than two million light-years.

At the central part of the map there is the Milky Way disk. There are irregular and dark structures. They correspond to areas where the star density observed by Gaia is lower due to gas and interstellar dust. This material blocks the light of the distant stars that lie behind.

At a large-scale there can be seen some structures (lines and curves) that respond to the satellite scan law, which defines where the scanning takes place. Therefore, the shiniest areas are the ones that the satellite has seen more over these 14 months. After the 5-year mission these lines will eventually fade out.

Gaia Mission

The Gaia satellite, which was launched in December 2013, is destined to create the most accurate map of the Milky Way. By making accurate measurements of the positions and motions of stars in the Milky Way, it will answer questions about the origin and evolution of our home galaxy.

Over its first two operating years, Gaia obtained 500.000 individual million images and 110.000 million spectrums, more than everything found previously over centuries.

The first data release, containing among other things three-dimensional positions and two-dimensional motions of a subset of two million stars, demonstrates that Gaia’s measurements are as precise as planned, paving the way to create the full map of one billion stars to be released towards the end of 2017.

Participation of the ICCUB team

The team of Institute of Cosmos Sciences (IEEC-UB), led by Professor Jordi Torra has participated in the Gaia mission from the very beginning with an outstanding role: they contributed to its scientific and technologic design, plus the database prototypes and data simulation production during the preparation stages of the mission.

Regarding the first data to be released, the team from Barcelona leads the group that works on the creation of the mission archive. They are also in charge of launching the initial process for the treatment of the data that arrive daily to the satellite, the first step to obtain scientific results such as the ones being published. The team is responsible for the matching of several observations in the same star and collaborates in the calibration of the stars brightness.

It is also worth mentioning that Barcelona is the headquarters of one of the data processing centres of the mission, in which there are Consorci de Serveis Universitaris de Catalunya (Consortium for University Services of Catalonia; CSUC) and Barcelona Supercomupting Center (BSC). This centre provides with the resources to carry out a part of the operations during the mission and it was essential in the preparation and verification tasks, as well as data simulation.

Around twenty scientists and engineers make the Gaia-ICCUB/IEEC team. It is built into the Data Processing and Analysis Consortium (DPAC), which gathers more than 400 people from around twenty European countries.

Under this agreement, Spain will receive 10% of the observation time, to share between the network in the northern hemisphere and the South. Spain’s future contribution to the construction of telescopes will facilitate the access of Spanish groups to additional observation time as part of the Observatory key scientific programs and time to be offered in open competition to all members of the same countries.

ICCUB researchers, which are part of the CTA Consortium, will take also take advantadge of this agreement. The High Energy Astrophysics Group of the ICCUB, led by the professor and scientific director Josep María Paredes and the aggregate professor Marc Ribó, has participated in the scientific objectives definition of the project and, in collaboration with a team of ICCUB engineers, they are contributing to the design and production microelecronics for CTA cameras.
Other groups of the Institut d'Estudis Espacials de Catalunya (IEEC), to which the ICCUB is part, are also deeply involved in the CTA project (for more information, see the IEEC webpage)

Source: IEEC news

The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us — and it may also be the closest possible abode for life outside the Solar System.

The team led by Guillem Anglada-Escudé (professor at Queen Mary University of London and doctorate from the University of Barcelona), has found a tiny back and forth wobble in the star attributed to its gravitational interaction with the planet, which has been final data for the acceptance of the finding.


The team was working in the Pale Red Dot Campaign analysing data from earlier observations made at ESO observatories and elsewhere. A careful analysis of the tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.

ESO news

Barcelona July 14, 2016. A team of researchers from the collaboration Sloan Digital Sky Survey III (SDSS-III) have presented this week the latest results obtained from the map obtained by the consortium with data collected over the past ten years. The analysis of the data has been carried out by researchers of this collaboration, including a team from the Institute of Cosmos Sciences at the University of Barcelona (ICCUB).

The results presented this week are the work of the galaxy group of the Baryon Oscillation Spectroscopic the Survey (BOSS), one of the programs of SDSS-III. They contain the measurements of 1.2 million galaxies over a quarter part of the sky to create a 3D map of the structure of the Universe.

The challenge of BOSS has been to combine precise measurements of how galaxies group in the large-scale structure of the Universe, which is known as the cosmic web. These galaxies span a volume of the observable Universe equivalent to a cube of 8,500 million light years on a side, combined with a detailed modeling using cosmological simulations.

The results are presented in a main article and twelve supporting articles published in the digital repository ArXiv and submitted to the scientific journal Monthly Notices of the Royal Astronomical Society. Among the seventy authors who have signed the main article are Licia Verde, ICREA researcher of the ICCUB, and Antonio Cuesta of the same institution. Both are also members of the Institute for Space Studies of Catalonia (IEEC). Other coauthors include researchers from the Institute of Astrophysics of the Canary Islands (IAC) and the Institute for Theoretical Physics (UAM-CSIC).

One of the main consequences of the results from BOSS is that they constrain very precisely the expansion history of the Universe, which places very restrictive limits to theoretical models of dark energy alternative to the cosmological constant introduced by Einstein.

"In fact, it looks like BOSS results are consistent with a cosmological model of a flat Universe dominated by a cosmological constant, and with a cold dark matter component, which corresponds to the standard cosmological model developed in the last twenty years", says Licia Verde, ICCUB researcher.

The scale of the Universe

In order to get this map of the cosmic web, BOSS has been able to establish a measurement of the distance to galaxies and quasars at cosmological scales, specifying the relationship between the distance to these objects and the expansion of the Universe. The light of these observed galaxies was emitted between 2,000 and 7,000 million years ago, covering approximately half of the expansion history of the Universe, whose age is estimated at about 13,800 million years. The data obtained trace the tug-of-war between gravity and expansion of the Universe, during its phase of accelerated expansion. Thus, the map presented by BOSS allows astronomers to measure the rate of expansion of the Universe and thus determine the amounts of dark matter and dark energy that make up the Universe today.

To carry out this map BOSS has used a technique based on the measurement of the so-called baryon acoustic oscillations (BAO), which are acoustic waves, also called pressure waves, that spread through matter in the early Universe, leaving their footprint on the small density fluctuations that existed at its beginning. These waves have a known length, allowing scientists to measure distances and thus deduce the expansion rate of the Universe in the past.

"The baryon acoustic oscillations method used by BOSS, has become one of the essential pillars of modern cosmology to understand the expansion history of the Universe and hence dark energy", says Licia Verde.

The main fact in which this technique is based is that galaxies tend to be separated by a typical distance, which astronomers call the BAO scale. The primordial measurement of the BAO scale has been perfectly determined by observations of the cosmic microwave background made by the Planck satellite, which estimates the length of this BAO scale as 481 million light-years.

BOSS: Building the 'cosmic web'

Another major feature in this article has been the study of the implications that BOSS data have when combined with the measurements of the cosmic microwave background by the Planck satellite. Researchers have analyzed from this data combination any possible deviations from the standard cosmological model regarding the curvature of the universe, dark energy, or the theory of gravity, and in all cases the result has been negative, a fact that reinforces the standard cosmological model.

Galaxies analyzed by BOSS reach to a distance of about 20 BAO scales, whereas the observable Universe has its horizon in about 100 BAO scales, so future missions, currently under construction, will continue to seek these modifications at distances greater than those reached by BOSS.

"But what is impressive about the BOSS experiment is that we have been able to measure cosmological distances with a precision of 1%. That is, if all galaxies we have observed were placed in a cube whose length is 20 meters on a side, just by looking to pairs of galaxies that are separated about 1 meter from each other, we have managed to measure the distances to all of them with a precision of centimeters", said Antonio Cuesta del ICCUB. Furthermore, "thanks to this data combination we have experienced a leap in the quality of our measurements of the cosmological parameters, and we have established a firm foundation on the future search for modifications of the standard cosmological model", concludes the ICCUB researcher.

Researchers at the University of Barcelona have led the computation of the correlation functions of BOSS galaxies and of artificial catalogs that simulate the observed data. This correlation function is precisely what determines the number of pairs of galaxies separated by a given distance.

Reference of the main article:

Alam, S. et al. (BOSS Collaboration). "The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological analysis of the DR12 galaxy sample." ArXiv, July 2016.

http://arxiv.org/abs/1607.03155

The SDSS Collaboration website is: http://www.sdss.org/



Section map of the large-scale structure of the Universe obtained by the BOSS program of the Sloan Digital Sky Survey collaboration. Each point of the image indicates the position of a galaxy whose light was emitted 6,000 million years ago. Each color indicates their distance from Earth, in a range from yellow for the closest ones, to violet for the most distant ones. The distribution of galaxies forms clusters, filaments and voids, constituting what is known as the cosmic web.

Image Credit: Daniel Eisenstein / SDSS-III.


Section of the 3D map built by BOSS. The rectangle on the left contains 120,000 galaxies which accounts for 10% of all measured by BOSS. Each point of the rectangle corresponds to the spectroscopic measurement of a galaxy, which is what makes the two-dimensional image a three-dimensional map, extending our vision of the Universe to 7,000 million years in the past, about half of the estimated age of the Universe.

Image Credit: Jeremy Tinker / SDSS-III.

Oficial press release: http://www.sdss.org/press-releases/astronomers-map-a-record-breaking-1-2-million-galaxies-to-study-the-properties-of-dark-energy/

UB Press release: http://www.ub.edu/web/ub/ca/menu_eines/noticies/2016/07/002.html

http://www.sciencedirect.com.sire.ub.edu/science/article/pii/S2212686416300267

The accuracy of state-of-the-art cosmological measurements allows us to obtain information about the mass of neutrinos. The new limits to this mass established using recent galaxy surveys are very interesting, in particular for the consequences for particle physics. They reveal that we might be near the discovery of the neutrino mass hierarchy and/or the measure of the mass of these enigmatic particles.

Researchers Antonio J. Cuesta and Licia Verde, from the Institute of Cosmos Sciences (IEEC-UB), and Viviana Niro, researcher from the Universidad Autónoma de Madrid, have recently published an academic work about neutrinos using the Universe as a huge detector. In this work they present cosmological upper limits on the sum of active neutrino masses using large-scale power spectrum data from the WiggleZ Dark Energy Survey and from the Sloan Digital Sky Survey - Data Release 7 sample of Luminous Red Galaxies.

More information: http://www.sciencedirect.com.sire.ub.edu/science/article/pii/S2212686416300267

Reference:
Antonio J. Cuesta, Viviana Niro & Licia Verde. “Neutrino mass limits: Robust information from the power spectrum of galaxy surveys”. Physics of the Dark Universe. DOI: 10.1016/j.dark.2016.04.005

Preplanned events leading up to the orbital insertion engine burn included changing the spacecraft’s attitude to point the main engine in the desired direction and then increasing the spacecraft’s rotation rate from 2 to 5 revolutions per minute (RPM) to help stabilize it.

The burn of Juno’s 645-Newton Leros-1b main engine began on time at 8:18 p.m. PDT (11:18 p.m. EDT), decreasing the spacecraft’s velocity by 1,212 miles per hour (542 meters per second) and allowing Juno to be captured in orbit around Jupiter. Soon after the burn was completed, Juno turned so that the sun’s rays could once again reach the 18,698 individual solar cells that give Juno its energy.

Over the next few months, Juno’s mission and science teams will perform final testing on the spacecraft’s subsystems, final calibration of science instruments and some science collection.

ServiAstro Juno special Web Page
NASA 's Juno special Web Page

On December 26, 2015 at 03:38:53 UTC, scientists observed gravitational waves — ripples in the fabric of spacetime — for the second time. The gravitational waves were detected by both of the twin Laser Interferometer Gravitational – Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.