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Category: cosmology – Page 3

Webb pushes boundaries of observable Universe closer to Big Bang

The NASA/ESA/CSA James Webb Space Telescope has topped itself once again, delivering on its promise to push the boundaries of the observable Universe closer to cosmic dawn with the confirmation of a bright galaxy that existed 280 million years after the Big Bang.

By now Webb has established that it will eventually surpass virtually every benchmark it sets in these early years, but the newly confirmed galaxy, MoM-z14, holds intriguing clues to the Universe’s historical timeline and just how different a place the early Universe was than astronomers expected.

“With Webb, we are able to see farther than humans ever have before, and it looks nothing like what we predicted, which is both challenging and exciting,” said Rohan Naidu of the Massachusetts Institute of Technology’s (MIT) Kavli Institute for Astrophysics and Space Research, lead author of a paper on galaxy MoM-z14 published in the Open Journal of Astrophysics.

NASA Webb Pushes Boundaries of Observable Universe Closer to Big Bang

NASA’s James Webb Space Telescope has topped itself once again, delivering on its promise to push the boundaries of the observable universe closer to cosmic dawn with the confirmation of a bright galaxy that existed 280 million years after the big bang. By now Webb has established that it will eventually surpass virtually every benchmark it sets in these early years, but the newly confirmed galaxy, MoM-z14, holds intriguing clues to the universe’s historical timeline and just how different a place the early universe was than astronomers expected.

“With Webb, we are able to see farther than humans ever have before, and it looks nothing like what we predicted, which is both challenging and exciting,” said Rohan Naidu of the Massachusetts Institute of Technology’s (MIT) Kavli Institute for Astrophysics and Space Research, lead author of a paper on galaxy MoM-z14 published in the Open Journal of Astrophysics.

Due to the expansion of the universe that is driven by dark energy, discussion of physical distances and “years ago” becomes tricky when looking this far. Using Webb’s NIRSpec (Near-Infrared Spectrograph) instrument, astronomers confirmed that MoM-z14 has a cosmological redshift of 14.44, meaning that its light has been travelling through (expanding) space, being stretched and “shifted” to longer, redder wavelengths, for about 13.5 of the universe’s estimated 13.8 billion years of existence.

Scientists may be approaching a ‘fundamental breakthrough in cosmology and particle physics’ — if dark matter and ’ghost particles’ can interact

Astronomers found evidence that dark matter and neutrinos may interact, hinting at a “fundamental breakthrough” that challenges our understanding of how the universe evolved.

‘The dream has come true’: Standard model of cosmology holds up in massive 6-year study of the universe — with one big caveat

The six-year Dark Energy Survey has released its full results, showing that two leading models of cosmology are equally valid — but both fail to explain one key observation.

Milky Way is embedded in a ‘large-scale sheet’ of dark matter, which explains motions of nearby galaxies

Computer simulations carried out by astronomers from the University of Groningen in collaboration with researchers from Germany, France and Sweden show that most of the (dark) matter beyond the Local Group of galaxies (which includes the Milky Way and the Andromeda galaxy) must be organized in an extended plane. Above and below this plane are large voids. The observed motions of nearby galaxies and the joint masses of the Milky Way and the Andromeda galaxy can only be properly explained with this “flat” mass distribution. The research, led by Ph.D. graduate Ewoud Wempe and Professor Amina Helmi, is published in Nature Astronomy.

Almost a century ago, astronomer Edwin Hubble discovered that virtually all galaxies are moving away from the Milky Way. This is important evidence for the expansion of the universe and for the Big Bang. But even in Hubble’s time, it was clear that there were exceptions. For example, our neighboring galaxy, Andromeda, is moving toward us at a speed of about 100 kilometers per second.

In fact, for half a century, astronomers have been wondering why most large nearby galaxies—with the exception of Andromeda—are moving away from us and do not seem to be affected by the mass and gravity of the so-called Local Group (the Milky Way, the Andromeda galaxy and dozens of smaller galaxies).

Earth’s Magnetic Field as Dark-Matter Sensor

One candidate for dark matter is a subatomic particle carrying a tiny electric charge many times smaller than that of the electron. This so-called millicharged dark matter would presumably interact with Earth’s magnetic field, generating potentially observable time variations in the magnetic field on Earth’s surface. A new study of archived data looked for this signal but came up empty [1]. The research has thus placed strict limits on the properties that a millicharged dark-matter particle could have if it has a small mass (in the range of 10–18 to 10–15 eV/c2).

Dark matter can’t have a typical electric charge, as it would interact too strongly with normal matter. But a small charge is possible and could produce features in-line with dark-matter models. Astrophysicists have looked for evidence of millicharged dark matter in stellar evolution data, as such particles could cause stars to cool faster than expected. No such signal has been seen, ruling out a large portion of millicharged-dark-matter parameter space.

Lei Wu from Nanjing Normal University in China and colleagues have explored another potential signal in the geomagnetic field. According to the team’s calculations, low-mass millicharged particles could annihilate each other in the presence of the planet’s magnetic-field background, producing an effective electric current that would generate its own magnetic field. This dark-matter-induced field would be small (roughly a million times less than Earth’s field), but it might be detectable owing to its peculiar time variation (at frequencies less than 1 Hz). The researchers failed to find such a signal in previously collected geomagnetic observations. The absence rules out low-mass dark-matter charges in a large range down to 10−30 times the electron charge. Such a small charge may seem implausible, but “nature sometimes surprises us,” Wu says.

High-resolution map shows dark matter’s gravity pulled normal matter into galaxies

Scientists have created the highest resolution map of the dark matter that threads through the universe—showing its influence on the formation of stars, galaxies and planets.

The research, including astronomers from Durham University, UK, tells us more about how this invisible substance helped pull ordinary matter into galaxies like the Milky Way and planets like Earth.

The findings, using new data from NASA’s James Webb Space Telescope (Webb), are published in the journal Nature Astronomy.

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