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Category: cosmology – Page 114

Results from the DESI (Dark Energy Spectroscopic Instrument) YR1 Data Release: a summary

The Dark Energy Spectroscopic Instrument (DESI) is a robotic instrument and spectrograph mounted on the Mayall Telescope in Kitt Peak, Arizona. The DESI collaboration aims primarily to understand the elusive Dark Energy. This is an energy of unknown source causing the Universe to accelerate in its expansion; this accelerating expansion is not predicted to occur for a universe that is filled with just ordinary matter and radiation (some more detail can be seen in this Astrobite). Since we still know so little about Dark Energy, a large galaxy survey can allow us to explore the history of the expansion of the Universe in more detail. The DESI instrument has 5,000 individual optical fibres controlled by robots that allow it to measure individual spectra of up to 5,000 galaxies in just a mere 20 minutes! Due to this design, and an observing program that optimises targets in the sky based on observing conditions, the survey will measure spectra of up to 35 million galaxies over 5 years. This will allow DESI to perform precise cosmological measurements, as a great volume of space and number of galaxies can be probed, and noise in the data products is reduced. This bite looks at the cosmology results from the collaboration’s analysis of the recently released Year 1 Data (YR1), in particular, via a signal that can be seen in the data known as Baryon Acoustic Oscillations.

DESI tracers

For the cosmological results in this work DESI uses information from various different ‘tracers’ – galaxies that trace the Large Scale Structure of the Universe. These consist of low redshift bright galaxies (BGS) that are measured when the moon lights the sky (and thus dimmer galaxies are less visible), and higher redshift galaxies measured during the dark time. The dimmer objects include luminous red galaxies (LRGs) which are elliptical galaxies that are extremely bright, emission line galaxies (ELGs) which are younger galaxies with emission line features in their spectra, and quasars (QSOs) which are very distant and bright galaxies that contain active galactic nuclei. The sample used also includes QSOs detected using Lyman-alpha forest measurements, or a method of tracing matter that utilises a series of absorption lines detected due to light from distant QSOs passing through neutral hydrogen in the space between us and the distant galaxies.

New model suggests partner anti-universe could explain accelerated expansion without the need for dark energy

The accelerated expansion of the present universe, believed to be driven by a mysterious dark energy, is one of the greatest puzzles in our understanding of the cosmos. The standard model of cosmology called Lambda-CDM, explains this expansion as a cosmological constant in Einstein’s field equations. However, the cosmological constant itself lacks a complete theoretical understanding, particularly regarding its very small positive value.

At 716 times per second, this neutron star is the universe’s fastest spinning celestial object

What makes PSR J1748–2446 famous for its weirdness? Easy. It is the celestial object that spins the fastest in the universe. It’s also a star whose surface is not just solid, but harder than a diamond. Compared to lead, its density is 50 trillion times higher. Compared to our Sun, its magnetic field sizzles a trillion times more intensely. It is, in essence, the most extreme form of neutron star.

When a heavy sun explodes in a supernova, the core of the sun, which has the mass of several million Earths, collapses into a tiny sphere and the rest of the sun shoots outward. This is how neutron stars are created. When this occurs, the inverse-square law of gravity goes into its demo-mode with a vengeance.

Dark matter could make our galaxy’s innermost stars immortal

They calculated stellar populations without and with the presence of dark matter. With dark matter, more massive stars experienced a lower dark matter density, and hydrogen in their core fused more slowly and their evolution was slowed down. But stars in a higher dark matter density region were changed significantly—they maintained equilibrium through dark matter burning with less fusion or no fusion, which led to a new stellar population in an HR region above the main sequence.

“Our simulations show that stars can survive on dark matter as a fuel alone,” said lead co-author Isabelle John from Stockholm University, “and because there is an extremely large amount of dark matter near the Galactic Center, these stars become immortal,” staying forever young, occupying a new, distinct, observable region of the HR diagram.

Their model may be able to explain more of the known mysteries. “For lighter stars, we see in our simulations that they become very puffy and might even lose parts of their outer layers,” said John. She noted that “something similar to this might be observed at the Galactic Center: the so-called G-objects, which might be star-like, but with a gas cloud around them.”

How Data From The Chandra X-Ray Observatory Helps With Studying Energetic Black Holes

🌌🔭 The Chandra X-ray Observatory has been unveiling the mysteries of the universe for 25 years! Discover how its X-ray data helps scientists study black holes, supernovae, and the formation of galaxies. Learn about the incredible insights gained and what the future holds for X-ray astronomy. #SpaceResearch #BlackHoles #Chandra

NASA’s Chandra X-ray Observatory detects X-ray emissions from astronomical events.

Blueprint of a Quantum Wormhole Teleporter Could Point to Deeper Physics

Transferring information from one location to another without transmitting any particles or energy seems to run counter to everything we’ve learned in the history of physics.

Yet there is some solid reasoning that this ‘counterfactual communication’ might not only be plausible, but depending on how it works could reveal fundamental aspects of reality that have so far been hidden from view.

Counterfactual physics isn’t a new thing in itself, describing a way of deducing activity by an absence of something. In one sense, it’s pretty straight forward. If your dog barks at strangers, and you hear silence when the front door opens, you’ve received information that says a familiar person has entered your house in spite of the absence of sound.

300 million years post-Big Bang? Oldest-ever galaxy discovered by NASA

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The JWST Advanced Deep Extragalactic Survey (JADES) program led to the discovery of this new galaxy dubbed JADES-GS-z14-0.

“The instruments on Webb were designed to find and understand the earliest galaxies, and in the first year of observations as part of the JWST Advanced Deep Extragalactic Survey (JADES), we found many hundreds of candidate galaxies from the first 650 million years after the big bang,” said Stefano Carniani from Scuola Normale Superiore in Pisa, Italy.

They stumbled across this exceptional galaxy in October 2023 while scouring through the vast pool of JADES program data.

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