Recommendable!
Showing posts with label astronomy. Show all posts
Showing posts with label astronomy. Show all posts
Tuesday, September 08, 2026
Thursday, September 03, 2026
Thursday, August 27, 2026
Gamma-ray signal could be long awaited evidence for WIMPs. Really!
Amazing stuff, but possibly wimpish!
Notice Big Bang, Dark matter & energy are perhaps some of the least plausible explanations/theories of our cosmos/universe/physics. E.g. what came before the Big Bang? Nothing?
Notice again how a popular science article deviates from the actually published research article. The abstract of the paper makes no mentioning of WIMPS. A case of journalistic sensationalism? Some skepsis is perhaps in order.
"Dark matter is known to make up roughly 85% of all mass in the universe, as evidenced by the way galaxies spin and how galaxy clusters are held together under gravity. Yet despite decades of searching, physicists have never managed to detect the elusive substance directly.
In new research ... claims to have spotted a strong gamma-ray signal coming from a group of galaxy clusters, which could be among the most compelling evidence yet for a leading dark matter candidate known as WIMPs.
Elusive particles
WIMPs, or weakly interacting massive particles, are hypothetical particles that barely interact with normal matter or light but would still exert a gravitational pull. ..."
From the abstract:
"As the largest gravitationally bound objects in the Universe, galaxy clusters have provided the first piece of evidence for the presence of dark matter and may be suitable targets for indirect dark matter searches.
Among various signals, the GeV-TeV 𝛾-ray line has been taken as the smoking-gun signal of the dark matter annihilation and decay, since no known astrophysical or physical process(es) could generate such a peculiar spectrum.
With 15.5 years of Fermi-LAT P8R3 publicly available data, we search for the 𝛾-ray line emission in the directions of 13 massive galaxy clusters at redshifts 𝑧 ≤0.028 with an unbinned likelihood analysis.
A 𝛾-ray line signal at ∼43.2 GeV has a net test statistic (TS) value of ≈30 if we take into account only the data in the directions of the Virgo, Fornax, and Ophiuchus clusters, three massive clusters with the highest J-factors expected to generate the dark matter annihilation signal.
The signal still presents when the data of 10 other nearby massive clusters are also included, though the TS value decreases to ≈21, likely because of their lower signal-to-noise ratios.
The absence of this signal in the inner Galaxy disfavors both the instrumental effect and the canonical dark matter annihilation interpretation, and a more sophisticated dark matter model or very peculiar astrophysical scenario might be needed.
This 𝛾-ray line signal, if intrinsic, could be unambiguously verified by the Very Large Area 𝛾-ray Space Telescope in its first two years of performance."
Evidence for a ∼43 GeV 𝛾-ray Line Signal in a Stacking Analysis of the Virgo, Fornax, and Ophiuchus Galaxy Clusters (no public access)
Evidence for a ∼43 GeV γ-ray line signal in a stacking analysis of the Virgo, Fornax, and Ophiuchus Galaxy clusters (preprint, open access, first published July 2024, but last updated July 2026)
Tuesday, August 18, 2026
Astronomers discover a brand-new type of astrophysical object: A black hole star
Amazing stuff!
"Astronomers ... have spotted an extremely bright red spot in the early universe. The object resembles an enormous star, spanning the size of our solar system. But it also is putting out 100 billion times more energy than any known star can physically produce. In fact, such energies are closer to what a black hole might generate.
The curious combination suggests that the red spot is an entirely new type of astrophysical source. The astronomers are calling it a “black hole star.” ..."
From the abstract:
"The physical processes that led to the formation of billion-solar-mass black holes within the first 700 million years of cosmic time, a period known as cosmic dawn, remain a puzzle.
Several theoretical scenarios have been proposed to seed and rapidly grow black holes, but direct observations of these mechanisms remain elusive.
Here we present a source 660 million years after the Big Bang that exhibits singular properties: among the largest hydrogen Balmer breaks reported at any redshift, broad multi-peaked Hβ emission, and Balmer line absorption in several transitions.
We model this source as an enshrouded black hole in which the Balmer break and absorption features are a result of extremely dense, turbulent gas forming a dust-free envelope around a supermassive black hole.
This source may provide evidence of an early black hole embedded in dense gas—a theoretical configuration proposed to rapidly grow black holes by super-Eddington accretion.
Radiation from the black hole seems to dominate almost all observed light, leaving limited room for contribution from its host galaxy. If the source merged with its brighter neighbour, it would resemble the recently discovered ‘little red dots’ with perplexing spectral energy distributions.
The redness of the black hole is due to gas, not dust, and scattering, not kinematics, gives rise to the complex line shapes and luminosities—black hole masses of these sources may therefore be overestimated by orders of magnitude."
Fig. 1: JWST imaging and spectroscopy of MoM-BH*-1.
Monday, August 17, 2026
Planet Venus may be geologically active
Amazing stuff! This was discovered on NASA images from the 1990s? What took so long?
Do we need a new Venus mission?
"... New research shows our planetary neighbor may be less dormant than thought. Scientists reanalyzed rift valleys on Venus’s surface, which are low-lying regions formed as the crust pulls apart or due to volcanic activity. On Venus, rift valleys can span as long as 10,000 kilometers ...
High-resolution computer models of the underlying geological processes revealed that broad ridges called rift flanks form at the valleys’ edges when they are either young or still forming. Soon after, the rift flanks widen and flatten as Venus’s crust relaxes. When the researchers looked at images of the venusian surface taken by NASA’s Magellan spacecraft in the 1990s, wide, high flanks were visible. The features indicate that the surface was active somewhat recently—and the world is far from dead. ..."
"In brief
- ETH researchers have developed innovative computer models to study the rift valley systems on Venus.
- The simulations indicate that recently formed rift valleys feature high, broad flanks, whereas older valleys tend to subside and are less elevated.
- The new findings can help us identify geologically active regions that require particularly close examination for future Venus missions.
..."
From the abstract:
"Rifts are prominent tectonic features on Venus, yet their formation, evolution and tectonic activity remain debatable.
Here we conducted 3D numerical thermomechanical experiments with visco-elasto-plastic compressible rock rheology to systematically investigate the rifting dynamics and topography under Venusian conditions. To compare active and inactive rift morphologies, the relaxation of rift topography after extension ceases was also investigated.
Our modelling results suggest a relatively thick thermal lithosphere and a strong crust with dry diabase or mafic granulite rheology in rifted regions and demonstrate that wide rift flank uplifts strongly indicate either presently ongoing Venusian rifting or activity within the past few tens of millions of years.
The rift valleys in the Ganis, Dali and Devana Chasmata have wide rift flank uplifts, and their characteristic topographic features are comparable to the modelled early-stage active rifts undergoing relatively high extension rates of 3−10 cm yr−1.
This suggests that the Venus rifts in these regions are still active or were active very recently. Their morphology also indicates faster extension rates than commonly assumed for Venusian rifting, potentially associated with recent vigorous mantle plume activity."
Venus: Dead? Far from it (original news release) "Simulations conducted by researchers at ETH Zurich suggest a strong likelihood that Venus’s rift valleys are still geologically active rather than being mere relics of a bygone era, as had been previously believed. This finding reshapes our understanding of Earth’s sister planet and will influence future missions to Venus. "
There are huge rift valleys on Venus. They suggest that the planet is still geologically active.
Sunday, August 16, 2026
Galactic spins carry fingerprints of the primordial universe
Amazing stuff!
"The origin of spin in spiral and elliptical galaxies has posed a long-standing puzzle for astronomers. One idea, known as tidal torque theory, proposes that galaxies' spins are an imprinted record of the early universe, imparted by gravity long before galaxies first formed and still detectable in galaxies today.
Through new research ... a team ... has put that idea to its toughest test yet. ...
Tidal torque theory suggests the origins of this spin can be traced back to the earliest structures in the universe, when uneven clumps of gas and dark matter pulled on their neighbors.
If such a primordial clump were slightly elongated, tidal torque theory suggests it would feel gravity's pull more strongly on the end closest to a massive neighbor. This lopsided tug would set it rotating, a motion that its descendant galaxy should inherit. ...
To tackle this challenge, Sheng's team turned to data from the ELUCID project, which reconstructs the distribution of matter in the early universe based on the positions of galaxies we can see today. Using this reconstruction, they traced the pattern of spins seen in currently observable galaxies back to the primordial tidal forces that created them.
They then compared this prediction with real spin measurements gathered using an instrument that maps the motion of gas and stars within individual galaxies, for a substantial sample drawn from the nearby universe. ..."
From the abstract:
"Tidal-torque theory predicts that galaxy angular momenta are imprinted by the primordial tidal field acting on proto-structures and that they can retain information about the early Universe through cosmic evolution.
Here we test this prediction by comparing observed galaxy angular momentum vectors with those predicted from the primordial density field reconstructed by ELUCID for the nearby Universe.
Among the galaxy populations considered, the gas component of central massive elliptical galaxies provides the clearest signal, exhibiting a strong direction correlation at a significance of about 7σ.
These results provide robust observational evidence for tidal-torque theory and open a window for cosmological measurements of neutrino mass and other cosmological parameters."
A high-significance detection of primordial tidal torque imprints (no public access)
A high-significance detection of primordial tidal torque imprints (preprint, open access)
Thursday, August 13, 2026
Wednesday, August 05, 2026
Sun Revealed In Stunning Clarity With Record-Breaking New Images
Update of 8/6/2026: "Telescope captures sun's surface in sharpest detail ever Researchers using the Daniel K. Inouye Solar Telescope in Hawaii have captured the highest-resolution images yet of the sun's outer shell. The images reveal feathery and rippling patterns caused by magnetized plasma ..." IEEE USA Smartbrief
Amazing stuff! We still know so little about the sun! What if the solar activity and cycles of the sun is the main cause of global warming/climate change?
Gallery Images from the Inouye
Diffuse puffs of “missing” matter surround most galaxies. Really!
Is the Big Bang real? What came before the Big Bang? God?
Is so called dark matter finally becoming matter?
However, it appears that the journalistic article promises/exaggerates/diverges too much relative to the abstract of the paper. Even the preprint does not agree! Regrettable!
"Now MIT scientists, as part of the CHIME/FRB Collaboration, are using far-off radio signals to reveal missing matter in the vast space between galaxies. The team has developed a new method to search out missing matter by combining locations of galaxies with detections of fast radio bursts. ...
A fast radio burst, or FRB, is an ultrabright, millisecond flash of radio waves emitted by extremely energetic phenomena in the distant universe. As it travels through space, the signal from a fast radio burst gets stretched, or “smeared,” in time. The more missing matter that it passes through, the more smeared the signal becomes.
The MIT-led team measured the degree of smearing experienced by thousands of FRB signals detected on Earth. Then they compared each FRB smear with locations of galaxies across the universe to determine how much of an FRB’s smearing was due to galaxy matter versus other, missing matter.
The new method revealed not only whether missing matter was present, but also where. Specifically, the researchers discovered that it exists in very diffuse clouds surrounding groups of galaxies. These clouds extend out from the galaxies, to much further distances than scientists had predicted. ..."
From the abstract:
"The dispersion of extragalactic fast radio bursts (FRBs) can serve as a powerful probe of the diffuse plasma between and surrounding galaxies, which contains most of the Universe’s baryons.
By cross-correlating the dispersion of background FRBs with the locations of foreground galaxies, we can study the relative spatial distributions of plasma and galaxies on scales of 0.1 to 50 Mpc, which are strongly affected by feedback processes in galaxy formation.
Here, we present the measurement of the dispersion-galaxy angular cross-power spectrum between 2870 FRBs from the Second CHIME/FRB Catalog and nearly 6 million galaxies from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Survey.
Over five photometric galaxy redshift bins spanning 0.05 <𝑧 <0.5 and at 4.9𝜎 significance, we make the first definitive detection of spatial correlations in FRB dispersion measure due to cosmic structure.
While parameter inferences should be interpreted with caution because of incomplete modeling of both the signal and systematic errors, our data indicate that the plasma-galaxy cross-power spectrum cuts off relative to the matter power spectrum at a scale 𝑘−1 cut=0.84+0.46 −0.34 Mpc.
This scale is consistent with those x-ray stacking analyses that suggest dark-matter halos with group-scale masses are largely evacuated of their baryons by feedback processes.
Our Letter demonstrates that FRBs are promising tools to discern the physics of baryonic structure formation and will only become more powerful as FRB surveys expand."
Tuesday, August 04, 2026
We Thought All Black Holes Came From Stars. We May Have Been Wrong with Matt O'Dowd
Very recommendable! Mostly about gravitational wave astronomy.
Thursday, July 30, 2026
Saturday, July 25, 2026
Saturday, July 18, 2026
The Universe Has Been Expanding Since the Big Bang. Just Not How We Thought with Matt O'Dowd
As usual, very recommendable, but not easy to follow!
Wednesday, July 15, 2026
Space is sweet: interstellar sugars found in our Milky Way galaxy
Amazing stuff!
"Astronomers have found sugars in interstellar medium for the first time, suggesting an answer to a riddle about the origin of life.
Sugars are critical organic molecules. They form the backbone of DNA and RNA as well as playing a key role in metabolic processes.
Scientists have long wondered how sugars first formed on Earth. ..."
From the abstract:
"Sugars are essential biomolecules, serving as metabolic fuels, nucleic acid backbone components and structural or energy-storage polymers.
A central question in origin-of-life research is how monosaccharides formed on the primitive Earth, as laboratory experiments under prebiotic conditions yield insufficient concentrations.
The detection of ribose, glucose and other monosaccharides in asteroids and meteorites suggests an exogenous origin, possibly in the interstellar medium (ISM) before meteoritic parent-body formation. However, no sugar has been observed in the ISM so far.
Here we report the discovery of erythrulose, a chiral four-carbon ketose, in the ISM. The detection was achieved through ultrasensitive, broadband spectral surveys of the Galactic Centre molecular cloud G+0.693−0.027, using the Yebes 40 m and IRAM 30 m telescopes.
Erythrulose appears to be at least eight times more abundant than analogous three-carbon sugars, which remain undetected in our ultrasensitive observations. Quantum chemical and astrochemical models indicate that erythrulose forms efficiently on interstellar dust grains from simpler two-carbon aldehydes and alcohols.
As ketoses readily isomerize into aldoses in aqueous conditions, interstellar erythrulose could have contributed to the sugar inventory available for early metabolic and replication processes."
Fig. 1: Brightest and most unblended transitions of erythrulose observed towards the G+0.693 molecular cloud.
Tuesday, July 07, 2026
Japan’s Hayabusa2 probe flew close by the double-lobed asteroid Torifune some 62 million miles from Earth
Amazing stuff!
"Japan’s Hayabusa2 probe flew close by the double-lobed asteroid Torifune on Sunday, capturing striking images of the 1,475-foot space rock some 62 million miles from Earth. ..."
Stunning!
Figure 1: Image of Asteroid Torifune captured by Hayabusa2. This image is a composite of photographs taken at intervals between 20 June and 21 June 2026. The small celestial body within the yellow square is Torifune, moving in the direction of the arrow. The image is a cropped section of approximately one square degree, created from images captured by the Optical Navigation Camera - Telescopic (ONC-T) with a scale of approximately 22.3 arcseconds per pixel.
Saturday, May 16, 2026
Astronomer, analyzing old satellite date with the help of AI may have just discovered over 10,000 more explanet candidates than previously known
Good news! We are not alone!
"Astronomers using AI found more than 10,000 possible new planets beyond our solar system in old NASA satellite data, a haul that could double the known exoplanet count if confirmed."
From the abstract:
"The T16 project has produced a uniformly detrended and systematics-corrected set of 83,717,159 TESS Cycle 1 full-frame image (FFI) light curves for stars observed by TESS in its primary mission down to T = 16 mag, enabling sensitive transit searches beyond the official TESS pipelines.
While most existing TESS planet searches focus on relatively bright targets, planet occurrence rates suggest that a substantial number of planets should exist around fainter stars. We therefore use the T16 light curves to conduct a semiautomated search for transiting exoplanets across the full Cycle 1 FFI sample, resulting in 11,554 planet candidates orbiting stars down to the 16th magnitude in the TESS band, with orbital periods between 0.5 and 27 days.
Of these, 10,091 are new planet candidates, and 411 are single-transit events, for which we do not attempt to determine orbital parameters. The remaining 1052 candidates are previously known TESS candidates.
We validate our pipeline through Magellan/Planet Finder Spectrograph radial-velocity follow-up measurements on one of our candidate hosts, TIC 183374187, a metal-poor thick-disk star, confirming the signal as a newly identified hot Jupiter, which we call TIC 183374187 b.
This detection demonstrates our pipeline’s ability to identify real, previously undiscovered, transiting planets.
Overall, this work shows that large-scale, machine learning–assisted transit searches of TESS FFIs can significantly expand the census of transiting planet candidates, in particular around faint stars, providing a rich target set for future validation and follow-up efforts. Our findings more than double the number of known TESS exoplanet candidates."
Figure 3. Left: example of automated off-center source detection. This example shows an off-center residual, indicating a blend as the source of the measured variability. The checkered pattern at the source position is consistent with Poisson noise or imperfect image subtraction due to the brightness of the source. Right: localized, on-center residual, indicating that the variability is due to the target.
Thursday, May 07, 2026
Solar System’s largest moon is unique with a still forming core for billions of years
Amazing stuff!
"In 1996, NASA’s Galileo spacecraft made a shocking discovery at Ganymede, Jupiter’s—and the Solar System’s—largest moon. Unlike every other known moon, it hosted an internally powered magnetic field called a dynamo. Now, scientists think the reason might make the moon doubly unique: its core may still be forming. ...
Typically, the elements within a planet or moon stratify over time, with heavier elements like iron sinking down to form a dense core. When that core churns, it generates electrical currents that sustain a magnetic field.
Scientists only know of such dynamos on the gas giants, Earth, and Mercury. But when researchers modeled the process on Ganymede to match the magnetic field measurements from Galileo, they found that the core might not simply be churning, but actively growing, with new iron still dripping down from rocks in the moon’s mantle. If true, that would render Ganymede the only known body still to be forming its center. ..."
From the abstract:
"Ganymede is the only known moon with an active dynamo today.
Previous studies interpret Ganymede’s dynamo as arising from convection in a metal core that formed billions of years ago.
However, Ganymede likely accreted too cold to form with a metal core, which confounds interpretations of Ganymede’s magnetic field as a constraint on the moon’s broader history.
Here, we reevaluate the thermal evolution of Ganymede’s rock-metal interior from a cold start. Our models show that Ganymede’s observed dynamo is consistent with ongoing core formation, a process not yet observed elsewhere.
If Ganymede has an Fe-FeS core with a sub-eutectic composition, then gradual mantle warming may expel dense Fe melt onto the growing protocore and stir liquid metal, sustaining a dynamo for billions of years."
Core of Solar System’s largest moon may still be forming "Ganymede discovery could force rethink of how worlds power their magnetic fields"
Fig. 1. Possible thermal evolution of Ganymede’s interior based on assumed initial temperatures.
Deep inside Jupiter’s largest moon, Ganymede, molten iron may be sinking, adding to a still-growing core.
Tuesday, April 07, 2026
Gravitational lensing could break the Hubble tension
Amazing stuff!
"How do you measure the distance to far off cosmic objects? That question is key to calculating the speed of the universe’s expansion and hence understanding its evolution and eventual fate. The rate of cosmic expansion, known as the Hubble constant, is so important for cosmologists that the disagreement among researchers over its value has its own name: the Hubble tension.
Astronomers measure it one way, using stars or supernovae with predictable brightness. Cosmologists have another way, studying ripples in the echo of the Big Bang and winding the clock forward to today. The two techniques have become increasingly precise, but they steadfastly disagree with each other.
A third method is needed to break the deadlock . That may come through the magic of gravitational lensing, which can cause a supernova—a star exploding at the end of its life—to appear to explode again and again. If a supernova is situated behind a large mass, such as a galaxy or cluster of galaxies, then as its light passes by the mass, its gravity bends the light along different paths, producing multiple images that show the explosion at different times when viewed from Earth. Using the time delays and path lengths, researchers can calculate the distance to the supernova and so calculate the Hubble constant.
Only a handful of such lensed supernovae have been found so far, but several upcoming survey telescopes, including the Vera C. Rubin Observatory, are expected to find them by the dozen and, hopefully, to ease the Hubble tension."
"... The idea goes back to the early 1960s, when gravitational lenses had only been theorized. But Sjur Refsdal, a graduate student at the University of Oslo, suggested a way to calculate how such a lens would bend light, using the same geometric tools used to model the paths of light through a glass lens. His thesis evaluators weren’t convinced—until he got the result published in the Monthly Notices of the Royal Astronomical Society in 1964. In the same issue, Refsdal also proposed a way to put his technique to work. He suggested time-delayed images of a lensed supernova could offer a handle on the Hubble constant."
A foreground galaxy (center) acts as a lens to produce four images of a background supernova in 2014. The supernova is dubbed SN Refsdal in honor of Sjur Refsdal, who predicted this effect 50 years earlier.
Tuesday, March 31, 2026
New theory reshapes quantum view of earliest expansion of Big Bang
Amazing stuff!
"... Their work suggests that the universe’s rapid early expansion could have arisen naturally from a deeper, more complete theory of quantum gravity. ...
research team that explored a novel method of combining gravity with quantum physics, the rules that govern how the smallest particles in the universe behave. While general relativity has been successful for more than a century, it breaks down at the extreme conditions that existed at the birth of the universe. To address this problem, the team used Quadratic Quantum Gravity, which remains mathematically consistent even at extremely high energies — similar to the kind present during the Big Bang.
Most existing explanations for the Big Bang rely on Einstein’s theory of gravity, plus additional components added by hand. This new approach offers a more unified picture that connects the earliest moments of the universe to the well-tested cosmology scientists observe today.
The research team found that the Big Bang’s rapid early expansion can emerge naturally from this simple, consistent theory of quantum gravity, without adding any extra ingredients. This early burst of expansion, often called inflation, is a central idea in modern cosmology because it explains why the universe looks the way it does today.
Their model also predicts a minimum amount of primordial gravitational waves, which are tiny ripples in spacetime geometry created in the first moments after the Big Bang. These signals may be detectable in upcoming experiments, offering a rare chance to test ideas about the universe’s quantum origins. ..."
From the abstract:
"We present a quantum quadratic gravity inflationary scenario that can accommodate the new cosmological constraints, which have disfavored Starobinsky inflation. The theory is asymptotically free in the ultraviolet, but 1-loop running is found to dynamically lead to slow-roll inflation toward the infrared. When a large number of matter fields contribute to the beta functions, the spectral index and the tensor-to-scalar ratio can be phenomenologically viable. We find that as inflation ends, the theory approaches its strong coupling regime and general relativity must emerge, as an effective field theory, as the universe must reheat and enter its standard radiation era. In order to avoid strong coupling, a minimum tensor-to-scalar ratio of 0.01 is predicted for this theory. Our framework offers a laboratory for connecting a concrete ultraviolet completion (quantum quadratic gravity) with inflationary dynamics, reheating, and precise cosmological observations."
New theory reshapes quantum view of Big Bang "Researchers show how the universe’s earliest expansion may emerge directly from quantum gravity"
Fig. 2.
Plot of the scalar spectral index ns vs the tensor-to-scalar ratio r for Starobinsky inflation (in black), contrasted with our QQG model in color for different values of the coupling λtH. The purple and dashed contours correspond to a combination of CMB (Planck18+ACT+SPT+Lensing+BK) and BAO (DESI) observational constraints for ΛCDM and w0waCDM cosmologies, respectively
Subscribe to:
Posts (Atom)