Scientists have used the tiny distortions imprinted on the cosmic microwave background by the gravity of matter throughout the Universe, recorded by ESA's Planck satellite, to uncover the connection between the luminosity of quasars – the bright cores of active galaxies – and the mass of the much larger 'halos' of dark matter in which they sit. The result is an important confirmation for our understanding of how galaxies evolve across cosmic history.

Astrophysical detection of the helium hydride ion HeH+

Astrophysical detection of the helium hydride ion HeH⁺, Published online: 17 April 2019; doi:10.1038/s41586-019-1090-x

Studies of the planetary nebula NGC 7027, using an upgraded spectrometer onboard a high-altitude observatory, have identified the rotational ground-state transition of the helium hydride ion—the first molecule to form after the Big Bang and an essential precursor to molecular hydrogen.

Portal origin URL: The Universe’s First Molecule Is Found at LastPortal origin nid: 443650Published: Wednesday, April 17, 2019 - 13:00Featured (stick to top of list): noPortal text teaser: Scientists detected the first type of molecule that ever formed, called helium hydride, using Stratospheric Observatory for Infrared Astronomy, or SOFIA.Portal image: Illustration of planetary nebula NGC 7027 and helium hydride molecules.Science Categories: Universe

Just one in 50 people in England experiences nights that are free from light pollution.

The cosmic drama that helped to build the Milky Way

The cosmic drama that helped to build the Milky Way, Published online: 16 April 2019; doi:10.1038/d41586-019-01226-2

Stellar baby boom added a slew of stars to the Galaxy’s disk.

NASA’s New Horizons mission has reached a small lump of rock and ice some 6.5 billion kilometres away in the Kuiper belt.

A powerful beam of microwaves fired into space could be used to detect hypothetical dark-matter particles called axions.

The final agreements have been signed to begin construction on the Cherenkov Telescope Array (CTA) in Chile.

The Italian astrophysicist Riccardo Giacconi, who shared the 2002 Nobel Prize for Physics with Raymond Davis Jr and Masatoshi Koshiba, has died at the age of 87.

Officials at the Square Kilometre Array (SKA) are set to convene in Rome this month to sign a convention to create an intergovernmental governing body for the huge radio telescope that is under construction in South Africa and Australia.

The UK and US have announced a $35m upgrade to the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO).

Asteroid, comet, alien ship or something else altogether? Astronomers are still unsure about the true nature of ‘Oumuamua – the first confirmed interstellar object to be detected in our solar system – as Andrew Glester finds

US astronomy graduate schools need to improve diversity and inclusion by collecting and analysing data on student demographics.

We present the POL-2 850~$\mu$m linear polarization map of the Barnard~1 clump in the Perseus molecular cloud complex from the B-fields In STar-forming Region Observations (BISTRO) survey at the James Clerk Maxwell Telescope. We find a trend of decreasing polarization fraction as a function of total intensity, which we link to depolarization effects towards higher density regions of the cloud. We then use the polarization data at 850~$\mu$m to infer the plane-of-sky orientation of the large-scale magnetic field in Barnard~1. This magnetic field runs North-South across most of the cloud, with the exception of B1-c where it turns more East-West. From the dispersion of polarization angles, we calculate a turbulence correlation length of $5.0 \pm 2.5$~arcsec ($1500$~au), and a turbulent-to-total magnetic energy ratio of $0.5 \pm 0.3$ inside the cloud. We combine this turbulent-to-total magnetic energy ratio with observations of NH$_3$ molecular lines from the Green Bank Ammonia Survey (GAS) to estimate the strength of the plane-of-sky component of the magnetic field through the Davis-Chandrasekhar-Fermi method. With a plane-of-sky amplitude of $120 \pm 60$~$\mu$G and a criticality criterion $\lambda_c = 3.0 \pm 1.5$, we find that Barnard~1 is a supercritical molecular cloud with a magnetic field nearly dominated by its turbulent component.

This 5th Announcement of Opportunity (AO), open to scientists affiliated with institutes located in ESA Member States, solicits proposals for participation as Science Planners in the NASA-led IRIS mission.

Einstein, Eddington and the 1919 eclipse

Einstein, Eddington and the 1919 eclipse, Published online: 15 April 2019; doi:10.1038/d41586-019-01172-z

Peter Coles weighs up three books on the momentous expedition that proved the general theory of relativity.

Shallow lakes on a moon of Saturn mysteriously vanish from view

Shallow lakes on a moon of Saturn mysteriously vanish from view, Published online: 15 April 2019; doi:10.1038/d41586-019-01221-7

Titan’s land of lakes includes bodies that were seen in winter but had disappeared by the onset of spring.

The results, reported in the Monthly Notices of the Royal Astronomical Society, have enabled astronomers to zero in on the time when reionisation ended and the universe emerged from a cold and dark state to become what it is today: full of hot and ionised hydrogen gas permeating the space between luminous galaxies.

Hydrogen gas dims light from distant galaxies much like streetlights are dimmed by fog on a winter morning. By observing this dimming in the spectra of a special type of bright galaxies, called quasars, astronomers can study conditions in the early universe.

In the last few years, observations of this specific dimming pattern (called the Lyman-alpha Forest) suggested that the fogginess of the universe varies significantly from one part of the universe to another, but the reason behind these variations was unknown.

“We expected the light from quasars to vary from place to place at most by a factor of two at this time, but it is seen to vary by a factor of about 500,” said lead author Girish Kulkarni, who completed the research while a postdoctoral researcher at the University of Cambridge. “Some hypotheses were put forward for why this is so, but none were satisfactory.”

The new study concludes that these variations result from large regions full of cold hydrogen gas present in the universe when it was just one billion years old, a result which enables researchers to pinpoint when reionisation ended.

During reionisation, when the universe transitioned out of the cosmic ‘dark ages’, the space between galaxies was filled with a plasma of ionised hydrogen with a temperature of about 10,000˚C. This is puzzling because fifty million years after the big bang, the universe was cold and dark. It contained gas with temperatures only a few degrees above absolute zero, and no luminous stars and galaxies. How is it then that today, about 13.6 billion years later, the universe is bathed in light from stars in a variety of galaxies, and the gas is a thousand times hotter?

Answering this question has been an important goal of cosmological research over the last two decades. The conclusions of the new study suggest that reionisation occurred 1.1 billion years after the big bang (or 12.7 billion years ago), quite a bit later than previously thought.

The team of researchers from India, the UK, Canada, Germany, and France drew their conclusions with the help of state-of-the-art computer simulations performed on supercomputers based at the Universities of Cambridge, Durham, and Paris, funded by the UK Science and Technology Facilities Council (STFC) and the Partnership for Advanced Computing in Europe (PRACE).

“When the universe was 1.1 billion years old there were still large pockets of the cosmos where the gas between galaxies was still cold and it is these neutral islands of cold gas that explain the puzzling observations,” said Martin Haehnelt of the University of Cambridge, who led the group that conducted this research, supported by funding from the European Research Council (ERC).

“This finally allows us to pinpoint the end of reionisation much more accurately than before,” said Laura Keating of the Canadian Institute of Theoretical Astrophysics.

The new study suggests that the universe was reionised by light from young stars in the first galaxies to form.

“Late reionisation is also good news for future experiments that aim to detect the neutral hydrogen from the early universe,” said Kulkarni, who is now based at the Tata Institute of Fundamental Research in India. “The later the reionisation, the easier it will be for these experiments to succeed.”

One such experiment is the ten-nation Square Kilometre Array (SKA) of which Canada, France, India, and the UK are members.

Reference:
Girish Kulkarni et al. ‘Large Ly α opacity fluctuations and low CMB τ in models of late reionisation with large islands of neutral hydrogen extending to z < 5:5.’ Monthly Notices of the Royal Astronomical Society (2019). DOI: 10.1093/mnrasl/slz025

Large differences in the ‘fogginess’ of the early universe were caused by islands of cold gas left behind when the universe heated up after the big bang, according to an international team of astronomers.

These neutral islands of cold gas explain the puzzling observationsMartin HaehneltAmanda Smith, Institute of AstronomyArtist's impression of reionisation period

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The first batch of charge-coupled devices, or CCDs, to be flown on ESA's PLATO space observatory was accepted by ESA last month. This is an important milestone on the road to creating a groundbreaking spacecraft that will detect Earth-sized exoplanets in orbit around nearby stars.

How scientists reacted to the first-ever image of a black hole

How scientists reacted to the first-ever image of a black hole, Published online: 11 April 2019; doi:10.1038/d41586-019-01191-w

We asked researchers what the breakthrough means for them and for science.