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New JWST data confirms, worsens the Hubble tension

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One of today’s greatest cosmic puzzles concerns the expanding Universe.

For the first several billion years of our Universe’s history, the Universe’s expansion rate was decreasing and distant galaxies slow in their recession from ours, as the matter and radiation densities drop. However, for the past ~6 billion years, distant galaxies have been speeding up in their recession, and the expansion rate, though still dropping, is not headed toward zero. Two different methods of measuring the expanding rate give conflicting values; the actual rate of expansion remains controversial.

Credit: NASA/STSci/Ann Feild

Two major methods each give low-error, but incompatible, answers.

flight through universe CEERS JWST NASA

Taking us beyond the limits of any prior observatory, including all of the ground-based telescopes on Earth as well as Hubble, NASA’s JWST has shown us the most distant galaxies in the Universe ever discovered. If we assign 3D positions to the galaxies that have been sufficiently observed-and-measured, we can construct a visualized fly-through of the Universe, as the CEERS data from JWST enables us to do here. Measuring the expansion rate is a challenge, as different methods yield different, mutually incompatible results.

Credits: Frank Summers (STScI), Greg Bacon (STScI), Joseph DePasquale (STScI), Leah Hustak (STScI), Joseph Olmsted (STScI), Alyssa Pagan (STScI); Science by: Steve Finkelstein (UT Austin), Rebecca Larson (RIT), Micaela Bagley (UT Austin)

By tracking an early, relic signal’s evolution, we measure expansion of 67 km/s/Mpc.

acoustic scale Bao CMB

We can look arbitrarily far back in the Universe if our telescopes allow, and the clustering of galaxies should reveal a specific distance scale – the acoustic scale – that should evolve with time in a particular fashion, just as the acoustic “peaks and valleys” in the cosmic microwave background reveal this scale as well. The evolution of this scale, over time, is an early relic that reveals a low expansion rate of ~67 km/s/Mpc.

Credit: E M Huff, the SDSS-III team and the South Pole Telescope team; graphic by Zosia Rostomian

By starting nearby and observing increasing recession with distance, we measure 73 km/s/Mpc.

cosmic distance ladder

The construction of the cosmic distance ladder involves going from our Solar System to the stars to nearby galaxies to distant ones. Each “step” carries along its own uncertainties, especially the steps where the different “rungs” of the ladder connect. However, recent improvements in the distance ladder have demonstrated how robust its results are.

Credit: NASA, ESA, A. Feild (STScI), and A. Riess (JHU)

This discrepancy — the “Hubble tension” — is a modern cosmic conundrum.

early dark energy

Modern measurement tensions from the distance ladder (red) with early signal data from the CMB and BAO (blue) shown for contrast. It is plausible that the early signal method is correct and there’s a fundamental flaw with the distance ladder; it’s plausible that there’s a small-scale error biasing the early signal method and the distance ladder is correct, or that both groups are right and some form of new physics (shown at top) is the culprit. The idea that there was an early form of dark energy is interesting, but that would imply more dark energy at early times, and that it has (mostly) since decayed away.

Credit: A.G. Riess, Nat Rev Phys, 2020

Many speculate an observational error on the “distance ladder” side could be the culprit.

expansion of the Universe

Back in 2001, there were many different sources of error that could have biased the best distance ladder measurements of the Hubble constant, and the expansion of the Universe, to substantially higher or lower values. Thanks to the painstaking and careful work of many, that is no longer possible, as errors have been greatly reduced. New JWST work, not shown here, has reduced Cepheid-related and period-luminosity errors even further than is shown here.

Credit: A.G. Riess et al., ApJ, 2022

We start by observing Cepheid variable stars within the Milky Way.

RS Puppis hubble light echo

The Variable Star RS Puppis, with its light echoes shining through the interstellar clouds. Variable stars come in many varieties; one of them, Cepheid variables, can be measured both within our own galaxy and in galaxies up to 50–60 million light years away. This enables us to extrapolate distances from our own galaxy to far more distant ones in the Universe. RR Lyrae and tip-of-the AGB branch stars can be used in a similar fashion.

Credit: NASA, ESA, G. Bacon (STScI), the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration, and H. Bond (STScI and Pennsylvania State University)

We accurately infer their distances by measuring astronomical parallax.

parallax

The stars that are closest to Earth will appear to shift periodically with respect to the more distant stars as the Earth moves through space in orbit around the Sun. Before the heliocentric model was established, we weren’t looking for “shifts” with a ~300,000,000 kilometer baseline over the span of ~6 months, but rather a ~12,000 kilometer baseline over the span of one night: Earth’s diameter as it rotated on its axis. The distances to the stars are so great that it wasn’t until the 1830s that the first parallax, with a 300 million km baseline, was detected. Today, we’ve measured the parallax of over 1 billion stars with ESA’s Gaia mission.

Credit: ESA/ATG medialab

Then we measure Cepheids in nearby, well-measured galaxies.

cepheids jwst NGC 4258 NGC 5584

The top two panels show two nearby, Cepheid-rich galaxies: NGC 4258 (left) and NGC 5584 (right), with JWST’s field-of-view overlaid atop them. The bottom panels show JWST views, with individually identified Cepheid variables highlighted in each image.

Credit: A.G. Riess et al., ApJ submitted/arXiv:2307.15806, 2023

Finally, we measure type Ia supernovae within those galaxies and beyond, linking these cosmic “rungs” together.

cepheids and SN ia together

As recently as 2019, there were only 19 published galaxies that contained distances as measured by Cepheid variable stars that also were observed to have type Ia supernovae occur in them. We now have distance measurements from individual stars in galaxies that also hosted at least one type Ia supernova in 42 galaxies, 35 of which have excellent Hubble imagery. Those 35 galaxies are shown here.

Credit: A.G. Riess et al., ApJ, 2022

Could an error in Cepheids be biasing our measured expansion rate?

expansion of the Universe

Using the cosmic distance ladder means stitching together different cosmic scales, where one always worries about uncertainties where the different “rungs” of the ladder connect. As shown here, we are now down to as few as three “rungs” on that ladder, and the full set of measurements agree with one another spectacularly.

Credit: A.G. Riess et al., ApJ, 2022

By measuring Cepheids in nearby galaxies, JWST probes this possibility.

nearby galaxy M106 NGC 4258

This nearby spiral galaxy, NGC 4258 (also known as Messier 106), is just ~20 million light-years away but contains many known Cepheids that are similar to Cepheids found in the Milky Way. This is an important galaxy for calibrating the cosmic distance ladder.

Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and R. Gendler (for the Hubble Heritage Team); Acknowledgment: J. GaBany

Observing galaxy NGC 4258, JWST found no photometric bias for Cepheids.

cepheids jwst hst NGC 4258

This image shows several Cepheid variable stars with different periods within nearby galaxy NGC 4258: an important galaxy for Cepheid and distance calibrations. The bottom 6 rows show the same stars as measured by both Hubble (grey labels) and JWST (purple labels) at various wavelengths. The superior resolution in JWST images reduces prior Hubble errors by significant, substantial amounts while validating and remaining consistent with prior results.

Credit: A.G. Riess et al., ApJ submitted/arXiv:2307.15806, 2023

Instead, it confirmed and enhanced previous Hubble Space Telescope findings.

NGC 5584 with supernova SN 2007af

This composite image shows the barred spiral galaxy NGC 5584 with supernova SN 2007af shining brightly within it. Nearby galaxies with identifiable Cepheid variable stars and that have hosted at least one type Ia supernova within them are incredibly important to the cosmic distance ladder method of measuring the expanding Universe.

Credit: ESO

Cepheids in NGC 5584, which also had a (2007-era) type Ia supernova, also reveal no bias.

JWST hubble tension data calibration

This graph shows the relationship between the magnitude of the brightness of Cepheid variable stars (y-axis) versus their period of variability (x-axis) in galaxies NGC 5584 (top) and NGC 4258 (bottom). The new JWST data is shown in red, while the old Hubble data is shown in grey. The errors and uncertainties of this relation in both galaxies are greatly reduced, primarily owing to JWST’s superior resolution over Hubble’s.

Credit: A.G. Riess et al., ApJ submitted/arXiv:2307.15806, 2023

The period-luminosity relation, a key calibrator of Cepheids, is now more precise than ever.

A graph illustrating the tension between JWST and Hubble in terms of different types of work.

By enabling a better understanding of Cepheid variables in nearby galaxies NGC 4258 and NGC 5584, JWST has reduced the uncertainties in their distances even further. The lowest points on the graph show the estimate for the distance to NGC 5584 from the expansion rates inferred from the distance ladder (left side) and what’s expected from the early relic method (right side). The mismatch is significant and compelling.

Credit: A.G. Riess et al., ApJ submitted/arXiv:2307.15806, 2023

With superior resolution, JWST has reduced any uncertainties down to their smallest values ever.

expansion of the Universe

Standard candles (left) and standard rulers (right) are two different techniques astronomers used to measure the expansion of space at various times/distances in the past. Based on how quantities like luminosity or angular size change with distance, we can infer the expansion history of the Universe. Using the candle method is part of the distance ladder, yielding 73 km/s/Mpc. Using the ruler is part of the early signal method, yielding 67 km/s/Mpc. With new JWST data, the mystery over the Universe’s expansion rate has deepened further.

Credit: NASA/JPL-Caltech

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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