Black holes born in the early Universe could account for the recently observed ultrahigh-energy astrophysical neutrinos.
Category: cosmology – Page 7
Primordial black hole’s final burst may solve neutrino mystery
The last gasp of a primordial black hole may be the source of the highest-energy “ghost particle” detected to date, a new MIT study proposes.
In a paper appearing today in Physical Review Letters, MIT physicists put forth a strong theoretical case that a recently observed, highly energetic neutrino may have been the product of a primordial black hole exploding outside our solar system.
Neutrinos are sometimes referred to as ghost particles, for their invisible yet pervasive nature: They are the most abundant particle type in the universe, yet they leave barely a trace. Scientists recently identified signs of a neutrino with the highest energy ever recorded, but the source of such an unusually powerful particle has yet to be confirmed.
Shape-shifting collisions offer new tool for studying early matter produced in Big Bang’s aftermath
This summer, the Large Hadron Collider (LHC) took a breath of fresh air. Normally filled with beams of protons, the 27-km ring was reconfigured to enable its first oxygen–oxygen and neon–neon collisions. First results from the new data, recorded over a period of six days by the ALICE, ATLAS, CMS and LHCb experiments, were presented during the Initial Stages conference held in Taipei, Taiwan, on 7–12 September.
Smashing atomic nuclei into one another allows physicists to study the quark–gluon plasma (QGP), an extreme state of matter that mimics the conditions of the universe during its first microseconds, before atoms formed. Until now, exploration of this hot and dense state of free particles at the LHC relied on collisions between heavy ions (like lead or xenon), which maximize the size of the plasma droplet created.
Collisions between lighter ions, such as oxygen, open a new window on the QGP to better understand its characteristics and evolution. Not only are they smaller than lead or xenon, allowing a better investigation of the minimum size of nuclei needed to create the QGP, but they are less regular in shape. A neon nucleus, for example, is predicted to be elongated like a bowling pin—a picture that has now been brought into sharper focus thanks to the new LHC results.
JWST observations discover a small star-forming complex
Using the James Webb Space Telescope (JWST), astronomers have detected what appears to be a faint and small star-forming complex. The discovery of the new complex, which received the designation LAP2, is detailed in a research paper published Sept. 8 on the arXiv preprint server.
The hypothetical Population III stars, composed almost entirely of primordial gas, are theorized to be the first stars to form after the Big Bang. Finding very low-metallicity, low-mass sources at high-redshifts could be crucial to investigating these stars, as they provide a rare glimpse of galaxies under conditions similar to those of the early universe. This could help us understand, for instance, how the first generations of stars enriched the cosmos with heavier elements.
Recently, a team of astronomers led by Eros Vanzella of the Astrophysics and Space Science Observatory of Bologna, Italy, inspected one such high-redshift, metal-poor and low-mass source. The source was identified behind the galaxy cluster Abell 2,744, which acts as a strong lens.
Gravitational wave analysis confirms theory of merging black holes
Ten years after scientists first detected gravitational waves emerging from two colliding black holes, the LIGO-Virgo-KAGRA collaboration, a research team that includes Columbia astronomy professor Maximiliano Isi, has recorded a signal from a nearly identical black hole collision.
Improvements in the detection technology allowed the researchers to see the black holes almost four times as clearly as they could a decade ago, and to confirm two important predictions: That merging black holes only ever grow or remain stable in size—as the late physicist Stephen Hawking predicted—and that, when disturbed, they ring like a bell, as predicted by Albert Einstein’s theory of general relativity.
“This unprecedentedly clear signal of the black hole merger known as GW250114 puts to the test some of our most important conjectures about black holes and gravitational waves,” Isi said.
LHC’s first oxygen collisions signs of small-scale quark-gluon plasma
CMS scientists study the first-ever oxygen-oxygen collisions at the LHC, and observe signs of quarks and gluons losing energy when they travel through quark-gluon plasma – a state that existed just after the Big Bang.
When heavy ions such as lead (Pb) collide at nearly the speed of light inside the Large Hadron Collider (LHC), extreme conditions are created that can “melt” ordinary nuclear matter into a new state called the quark-gluon plasma (QGP). This hot and dense medium is believed to resemble the universe just microseconds after the Big Bang, when quarks and gluons – the fundamental building blocks of protons and neutrons – moved freely.
Physicists study the QGP medium by looking at how fast-moving quarks and gluons – collectively called partons – behave as they pass through it. Fast moving partons form sprays of particles, which can be seen as “jets” in particle detectors. In collisions of very small systems, such as proton-proton collisions, the observed jets are seen to retain the full energy or the original partons. In contrast, in heavy-ion collisions, the presence of the QGP medium leads to a significant loss of energy.
Mysterious ‘red dots’ in early universe may be ’black hole star‘ atmospheres
Tiny red objects spotted by NASA’s James Webb Space Telescope (JWST) are offering scientists new insights into the origins of galaxies in the universe—and may represent an entirely new class of celestial object: a black hole swallowing massive amounts of matter and spitting out light.
Using the first datasets released by the telescope in 2022, an international team of scientists including Penn State researchers discovered mysterious “little red dots.” The researchers suggested the objects may be galaxies that were as mature as our current Milky Way, which is roughly 13.6 billion years old, just 500 to 700 million years after the Big Bang.
Informally dubbed “universe breakers” by the team, the objects were originally thought to be galaxies far older than anyone expected in the infant universe—calling into question what scientists previously understood about galaxy formation.