ST/ NASA’s Webb finds ethanol, other icy ingredients for worlds

Paradigm

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Paradigm

30 min readMar 28, 2024

Space biweekly vol.94, 8th March — 28th March

TL;DR

Margaritas, vinegar, and ant stings share a commonality: chemical ingredients identified by NASA’s James Webb Space Telescope around protostars IRAS 2A and IRAS 23385.
The discovery suggests these molecules could play a crucial role in forming habitable worlds despite planets not yet forming around the stars.
A groundbreaking study challenges the existence of dark matter, presenting a new perspective on the universe’s composition.
Research indicates that the Rayleigh-Taylor instability might not fully explain the formation of hydrogen clumps around supernova 1987A, suggesting a different mechanism at play.
The ‘Hubble Tension,’ where the universe’s expansion rate surpasses astronomical expectations, remains a significant cosmological puzzle.
Experts urge collaboration between space regulators and tourism innovators to mitigate the risks of space weather radiation exposure.
Astronomers discover a ‘dead’ galaxy that ceased star formation over 13 billion years ago, observed using the James Webb Space Telescope.
Contrary to traditional beliefs, a group of white dwarf stars has halted cooling for over eight billion years, challenging existing theories.
Physicists highlight neutron star mergers as a promising source for new physics signals, potentially shedding light on dark matter’s true nature.
Geologists leverage Perseverance rover data to determine the original orientation of Mars bedrock samples, offering insights into their formation conditions.
And more!

Space industry in numbers

The global smart space market size is projected to grow from USD 9.4 billion in 2020 to USD 15.3 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 10.2% during the forecast period. The increasing venture capital funding and growing investments in smart space technology to drive market growth.

Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.

Source: Satellite Industry Association, Morgan Stanley Research, Thomson Reuters. *2040 estimates

Space industry news

Latest research

JWST Observations of Young protoStars (JOYS+): Detecting icy complex organic molecules and ions

by W. R. M. Rocha, E. F. van Dishoeck, M. E. Ressler, M. L. van Gelder, et al in Astronomy & Astrophysics

What do margaritas, vinegar, and ant stings have in common? They contain chemical ingredients that NASA’s James Webb Space Telescope has identified surrounding two young protostars known as IRAS 2A and IRAS 23385. Although planets are not yet forming around those stars, these and other molecules detected there by Webb represent key ingredients for making potentially habitable worlds.

An international team of astronomers used Webb’s MIRI (Mid-Infrared Instrument) to identify a variety of icy compounds made up of complex organic molecules like ethanol (alcohol) and likely acetic acid (an ingredient in vinegar). This work builds on previous Webb detections of diverse ices in a cold, dark molecular cloud.

This image at a wavelength of 15 microns was taken by MIRI (the Mid-Infrared Instrument) on NASA’s James Webb Space Telescope, of a region near the protostar known as IRAS 23385. IRAS 23385 and IRAS 2A (not visible in this image) were targets for a recent research effort by an international team of astronomers that used Webb to discover that the key ingredients for making potentially habitable worlds are present in early-stage protostars, where planets have not yet formed.

“This finding contributes to one of the long-standing questions in astrochemistry,” said team leader Will Rocha of Leiden University in the Netherlands. “What is the origin of complex organic molecules, or COMs, in space? Are they made in the gas phase or in ices? The detection of COMs in ices suggests that solid-phase chemical reactions on the surfaces of cold dust grains can build complex kinds of molecules.”

As several COMs, including those detected in the solid phase in this research, were previously detected in the warm gas phase, it is now believed that they originate from the sublimation of ices. Sublimation is to change directly from a solid to a gas without becoming a liquid. Therefore, detecting COMs in ices makes astronomers hopeful about improved understanding of the origins of other, even larger molecules in space.

Scientists are also keen to explore to what extent these COMs are transported to planets at much later stages of protostellar evolution. COMs in cold ices are thought to be easier to transport from molecular clouds to planet-forming disks than warm, gaseous molecules. These icy COMs can therefore be incorporated into comets and asteroids, which in turn may collide with forming planets, delivering the ingredients for life to possibly flourish.

The science team also detected simpler molecules, including formic acid (which causes the burning sensation of an ant sting), methane, formaldehyde, and sulfur dioxide. Research suggests that sulfur-containing compounds like sulfur dioxide played an important role in driving metabolic reactions on the primitive Earth.

Corner plots showing the IRAS 2A coefficient confidence intervals for the range between 7.5 and 7.8 µm. The grey scale colour is the Δχ2 map derived from a total of 5000 values. Yellow and red contours represent 2 and 3σ significance, respectively.

Of particular interest is that one of the sources investigated, IRAS 2A, is characterized as a low-mass protostar. IRAS 2A may therefore be similar to the early stages of our own solar system. As such, the chemicals identified around this protostar were likely present in the first stages of development of our solar system and later delivered to the primitive Earth.

“All of these molecules can become part of comets and asteroids and eventually new planetary systems when the icy material is transported inward to the planet-forming disk as the protostellar system evolves,” said Ewine van Dishoeck of Leiden University, one of the coordinators of the science program. “We look forward to following this astrochemical trail step-by-step with more Webb data in the coming years.”

Testing CCC+TL Cosmology with Observed Baryon Acoustic Oscillation Features

by Rajendra P. Gupta in The Astrophysical Journal

The current theoretical model for the composition of the universe is that it’s made of ‘normal matter,’ ‘dark energy’ and ‘dark matter.’ A new uOttawa study challenges this.

A University of Ottawa study published today challenges the current model of the universe by showing that, in fact, it has no room for dark matter.

In cosmology, the term “dark matter” describes all that appears not to interact with light or the electromagnetic field, or that can only be explained through gravitational force. We can’t see it, nor do we know what it’s made of, but it helps us understand how galaxies, planets and stars behave.

Rajendra Gupta, a physics professor at the Faculty of Science, used a combination of the covarying coupling constants (CCC) and “tired light” (TL) theories (the CCC+TL model) to reach this conclusion. This model combines two ideas — about how the forces of nature decrease over cosmic time and about light losing energy when it travels a long distance. It’s been tested and has been shown to match up with several observations, such as about how galaxies are spread out and how light from the early universe has evolved. This discovery challenges the prevailing understanding of the universe, which suggests that roughly 27% of it is composed of dark matter and less than 5% of ordinary matter, remaining being the dark energy.

The absolute scale of BAO estimated at different redshifts using the CCC+TL model.

“The study’s findings confirm that our previous work (“JWST early Universe observations and ΛCDM cosmology”) about the age of the universe being 26.7billionyears has allowed us to discover that the universe does not require dark matter to exist,” explains Gupta. “In standard cosmology, the accelerated expansion of the universe is said to be caused by dark energy but is in fact due to the weakening forces of nature as it expands, not due to dark energy.”

“Redshifts” refer to when light is shifted toward the red part of the spectrum. The researcher analyzed data from recent papers on the distribution of galaxies at low redshifts and the angular size of the sound horizon in the literature at high redshift.

“There are several papers that question the existence of dark matter, but mine is the first one, to my knowledge, that eliminates its cosmological existence while being consistent with key cosmological observations that we have had time to confirm,” says Gupta.

By challenging the need for dark matter in the universe and providing evidence for a new cosmological model, this study opens up new avenues for exploring the fundamental properties of the universe.

Hydrodynamic Mechanism for Clumping along the Equatorial Rings of SN1987A and Other Stars

by Michael J. Wadas, William J. White, Heath J. LeFevre, Carolyn C. Kuranz, Aaron Towne, Eric Johnsen in Physical Review Letters

Physicists often turn to the Rayleigh-Taylor instability to explain why fluid structures form in plasmas, but that may not be the full story when it comes to the ring of hydrogen clumps around supernova 1987A, research from the University of Michigan suggests.

In a study, the team argues that the Crow instability does a better job of explaining the “string of pearls” encircling the remnant of the star, shedding light on a longstanding astrophysical mystery.

“The fascinating part about this is that the same mechanism that breaks up airplane wakes could be in play here,” said Michael Wadas, corresponding author of the study and a graduate student in mechanical engineering at the time of the work.

In jet contrails, the Crow instability creates breaks in the smooth line of clouds because of the spiraling airflow coming off the end of each wing, known as wingtip vortices. These vortices flow into one another, creating gaps — something we can see because of the water vapor in the exhaust. And the Crow instability can do something that Rayleigh-Taylor could not: predict the number of clumps seen around the remnant.

“The Rayleigh-Taylor instability could tell you that there might be clumps, but it would be very difficult to pull a number out of it,” said Wadas, who is now a postdoctoral scholar at the California Institute of Technology.

Hot spots along the equatorial ring of SN1987A [5, 11] (a) and pinch-off of isolated vortex structures from a radially expanding vortex dipole in water [12] (b). Images are reproduced with permission.

Supernova 1987A is among the most famous stellar explosions because it’s relatively close to Earth at 163,000 light years away, and its light reached Earth at a time when sophisticated observatories existed to witness its evolution. It is the first supernova visible to the naked eye since Kepler’s supernova in 1604, making it an incredibly rare astrophysical event that has played an outsized role in shaping our understanding of stellar evolution.

While much is still unknown about the star that exploded, it is believed that the ring of gas surrounding the star ahead of the explosion came from the merger of two stars. Those stars shed hydrogen into the space around them as they became a blue giant tens of thousands of years before the supernova. That ring-shaped cloud of gas was then buffeted by the stream of high-speed charged particles coming off the blue giant, known as a stellar wind. The clumps are believed to have formed before the star exploded.

Isosurfaces of mass fraction (left) and Q criterion (right) at times tΓ/R20∈(0,0.1,0.7), which increase with increasing radius.

The researchers simulated the way the wind pushed the cloud outward while also dragging on the surface, with the top and bottom of the cloud being pushed out faster than the middle. This caused the cloud to curl in on itself, which triggered the Crow instability and caused it to break apart into fairly even clumps that became the string of pearls. The prediction of 32 is very close to the observed 30 to 40 clumps around the supernova 1987A remnant.

“That’s a big piece of why we think this is the Crow instability,” said Eric Johnsen, U-M professor of mechanical engineering and senior author of the study.

The team saw hints that the Crow instability might predict the formation of more beaded rings around the star, further out from the ring that appears brightest in telescope images. They were pleased to see that more clumps seem to appear in the shot from the James Webb Space Telescope’s near-infrared camera, released in August last year, Wadas explained. The team also suggested that the Crow instability might be at play when the dust around a star settles into planets, although further research is needed to explore this possibility.

JWST Observations Reject Unrecognized Crowding of Cepheid Photometry as an Explanation for the Hubble Tension at 8σ Confidence

by Adam G. Riess, Gagandeep S. Anand, Wenlong Yuan, Stefano Casertano, Andrew Dolphin, Lucas M. Macri, Louise Breuval, Dan Scolnic, Marshall Perrin, Richard I. Anderson in The Astrophysical Journal Letters

When you are trying to solve one of the biggest conundrums in cosmology, you should triple check your homework. The puzzle, called the “Hubble Tension,” is that the current rate of the expansion of the universe is faster than what astronomers expect it to be, based on the universe’s initial conditions and our present understanding of the universe’s evolution.

Scientists using NASA’s Hubble Space Telescope and many other telescopes consistently find a number that does not match predictions based on observations from ESA’s (European Space Agency’s) Planck mission. Does resolving this discrepancy require new physics? Or is it a result of measurement errors between the two different methods used to determine the rate of expansion of space?

Hubble has been measuring the current rate of the universe’s expansion for 30 years, and astronomers want to eliminate any lingering doubt about its accuracy. Now, Hubble and NASA’s James Webb Space Telescope have tag-teamed to produce definitive measurements, furthering the case that something else — not measurement errors — is influencing the expansion rate.

“With measurement errors negated, what remains is the real and exciting possibility we have misunderstood the universe,” said Adam Riess, a physicist at Johns Hopkins University in Baltimore. Riess holds a Nobel Prize for co-discovering the fact that the universe’s expansion is accelerating, due to a mysterious phenomenon now called “dark energy.”

NIRCam fields superimposed on Digitized Sky Survey color images for four hosts (top) and NIRCam RGB images (F090W/F150W/F277W) showing positions of Cepheids (cyan circles) (bottom). North is up and east is to the left.

As a crosscheck, an initial Webb observation in 2023 confirmed that Hubble measurements of the expanding universe were accurate. However, hoping to relieve the Hubble Tension, some scientists speculated that unseen errors in the measurement may grow and become visible as we look deeper into the universe. In particular, stellar crowding could affect brightness measurements of more distant stars in a systematic way. The SH0ES (Supernova H0 for the Equation of State of Dark Energy) team, led by Riess, obtained additional observations with Webb of objects that are critical cosmic milepost markers, known as Cepheid variable stars, which now can be correlated with the Hubble data.

“We’ve now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence,” Riess said.

The team’s first few Webb observations in 2023 were successful in showing Hubble was on the right track in firmly establishing the fidelity of the first rungs of the so-called cosmic distance ladder. Astronomers use various methods to measure relative distances in the universe, depending upon the object being observed. Collectively these techniques are known as the cosmic distance ladder — each rung or measurement technique relies upon the previous step for calibration. But some astronomers suggested that, moving outward along the “second rung,” the cosmic distance ladder might get shaky if the Cepheid measurements become less accurate with distance. Such inaccuracies could occur because the light of a Cepheid could blend with that of an adjacent star — an effect that could become more pronounced with distance as stars crowd together and become harder to distinguish from one another.

The observational challenge is that past Hubble images of these more distant Cepheid variables look more huddled and overlapping with neighboring stars at ever farther distances between us and their host galaxies, requiring careful accounting for this effect. Intervening dust further complicates the certainty of the measurements in visible light. Webb slices though the dust and naturally isolates the Cepheids from neighboring stars because its vision is sharper than Hubble’s at infrared wavelengths.

“Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder,” said Riess.

The new Webb observations include five host galaxies of eight Type Ia supernovae containing a total of 1,000 Cepheids, and reach out to the farthest galaxy where Cepheids have been well measured — NGC 5468 — at a distance of 130 million light-years. “This spans the full range where we made measurements with Hubble. So, we’ve gone to the end of the second rung of the cosmic distance ladder,” said co-author Gagandeep Anand of the Space Telescope Science Institute in Baltimore, which operates the Webb and Hubble telescopes for NASA.

Hubble and Webb’s further confirmation of the Hubble Tension sets up other observatories to possibly settle the mystery. NASA’s upcoming Nancy Grace Roman Space Telescope will do wide celestial surveys to study the influence of dark energy, the mysterious energy that is causing the expansion of the universe to accelerate. ESA’s Euclid observatory, with NASA contributions, is pursuing a similar task.

At present it’s as though the distance ladder observed by Hubble and Webb has firmly set an anchor point on one shoreline of a river, and the afterglow of the big bang observed by Planck’s measurement from the beginning of the universe is set firmly on the other side. How the universe’s expansion was changing in the billions of years between these two endpoints has yet to be directly observed. “We need to find out if we are missing something on how to connect the beginning of the universe and the present day,” said Riess.

A discussion on policies and regulations governing the risks associated with radiation exposure for space tourism flight participants

by C.T. Rees, J.R. Catchpole, K.A. Ryden in Space Policy

Space weather experts at the University of Surrey are urging regulators and space tourism innovators to work together to protect their passengers and crews from the risks of space weather radiation exposure.

The Earth’s atmosphere and magnetic field protect people on the ground from exposure to unpredictable surges of electrically charged particles coming from the sun. However, there can be dramatic increases in potential radiation exposure at higher altitudes, such as those envisaged for space tourist flights. Space weather cannot yet be predicted and can lead to health risks such as damage to DNA, and it could lead to cancer. Despite this, space tourists currently receive little information and few warnings.

Chris Rees, lead author of a new paper on radiation risks to space tourism and a postgraduate researcher at Surrey Space Centre, said: “Although space tourism is very niche, it will quickly grow as an industry. With increased flights, more people could be impacted by cosmic radiation exposure, especially during rapid changes in space weather. We’re recommending how regulators and industry should work together to keep people safe without unnecessarily holding back innovation.”
JR Catchpole, co-author of the paper and a space law expert at Foot Anstey LLP, said: “International action is needed by regulators, but meanwhile, the early movers in the sector, like Virgin Galactic and Blue Origin, need to watch themselves and their passengers. The principles of informed consent mean stronger warnings and clearer information may be required.”

The paper makes a series of recommendations:

Regulatory bodies should work closely with industry to ensure regulations are practical, effective and reflect technological advances
International standards are needed to ensure consistent regulations
Safety is crucial, which means clear information for space tourists and more monitoring of cosmic radiation during short space flights
Regulation must encourage innovation within this young industry, not stifle it

A recently quenched galaxy 700 million years after the Big Bang

by Tobias J. Looser, Francesco D’Eugenio, Roberto Maiolino, et al in Nature

A galaxy that suddenly stopped forming new stars more than 13 billion years ago has been observed by astronomers.

Using the James Webb Space Telescope, an international team of astronomers led by the University of Cambridge have spotted a ‘dead’ galaxy when the universe was just 700 million years old, the oldest such galaxy ever observed. This galaxy appears to have lived fast and died young: star formation happened quickly and stopped almost as quickly, which is unexpected for so early in the universe’s evolution. However, it is unclear whether this galaxy’s ‘quenched’ state is temporary or permanent, and what caused it to stop forming new stars.

The results could be important to help astronomers understand how and why galaxies stop forming new stars, and whether the factors affecting star formation have changed over billions of years.

“The first few hundred million years of the universe was a very active phase, with lots of gas clouds collapsing to form new stars,” said Tobias Looser from the Kavli Institute for Cosmology, the paper’s first author. “Galaxies need a rich supply of gas to form new stars, and the early universe was like an all-you-can-eat buffet.”
“It’s only later in the universe that we start to see galaxies stop forming stars, whether that’s due to a black hole or something else,” said co-author Dr Francesco D’Eugenio, also from the Kavli Institute for Cosmology.

False-colour JWST image of a small fraction of the GOODS South field, with JADES-GS-z7–01-QU highlighted. Credit: JADES Collaboration

Astronomers believe that star formation can be slowed or stopped by different factors, all of which will starve a galaxy of the gas it needs to form new stars. Internal factors, such as a supermassive black hole or feedback from star formation, can push gas out of the galaxy, causing star formation to stop rapidly. Alternatively, gas can be consumed very quickly by star formation, without being promptly replenished by fresh gas from the surroundings of the galaxy, resulting in galaxy starvation.

“We’re not sure if any of those scenarios can explain what we’ve now seen with Webb,” said co-author Professor Roberto Maiolino. “Until now, to understand the early universe, we’ve used models based on the modern universe. But now that we can see so much further back in time, and observe that the star formation was quenched so rapidly in this galaxy, models based on the modern universe may need to be revisited.”

Using data from JADES (JWST Advanced Deep Extragalactic Survey), the astronomers determined that this galaxy experienced a short and intense period of star formation over a period between 30 and 90 million years. But between 10 and 20 million years before the point in time where it was observed with Webb, star formation suddenly stopped.

“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” said Looser.

Astronomers have previously observed dead galaxies in the early universe, but this galaxy is the oldest yet — just 700 million years after the big bang, more than 13 billion years ago. This observation is one of the deepest yet made with Webb. In addition to the oldest, this galaxy is also relatively low mass — about the same as the Small Magellanic Cloud (SMC), a dwarf galaxy near the Milky Way, although the SMC is still forming new stars. Other quenched galaxies in the early universe have been far more massive, but Webb’s improved sensitivity allows smaller and fainter galaxies to be observed and analysed.

The astronomers say that although it appears dead at the time of observation, it’s possible that in the roughly 13 billion years since, this galaxy may have come back to life and started forming new stars again.

“We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” said D’Eugenio. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life — we’ll need more observations to help us figure that out.”

Buoyant crystals halt the cooling of white dwarf stars

by Antoine Bédard, Simon Blouin, Sihao Cheng in Nature

Open any astronomy textbook to the section on white dwarf stars and you’ll likely learn that they are “dead stars” that continuously cool down over time. New research is challenging this theory, with the University of Victoria (UVic) and its partners using data from the European Space Agency’s Gaia satellite to reveal why a population of white dwarf stars stopped cooling for more than eight billion years.

“We discovered the classical picture of all white dwarfs being dead stars is incomplete,” says Simon Blouin, co-principal investigator and Canadian Institute of Theoretical Astrophysics National Fellow at UVic. “For these white dwarfs to stop cooling, they must have some way of generating extra energy. We weren’t sure how this was happening, but now we have an explanation for the phenomenon.”

Understanding the age and other aspects of white dwarf stars helps scientists reconstruct the formation of the Milky Way Galaxy. Using 2019 Gaia data, Blouin collaborated with Antoine Bédard of the University of Warwick and Institute for Advanced Study researcher Sihao Cheng to make the discovery.

All sky view of the Milky Way taken by the European Space Agency’s Gaia space observatory. Credit: ESA/Gaia/DPAC, CC BY SA 3.0 IGO

Over 97 per cent of stars in the Milky Way will eventually become white dwarfs. Scientists have long considered these stars to be at the end of their lives. Having depleted their nuclear energy source, they stop producing heat and cool down until the dense plasma in their interiors freezes into a solid state, and the star solidifies from the inside out. This cooling process can take billions of years.

According to the new paper, in some white dwarfs, the dense plasma in the interior does not simply freeze from the inside out. Instead, the solid crystals that are formed upon freezing are less dense than the liquid, and therefore want to float. As the crystals float upwards, they displace the heavier liquid downward. The transport of heavier material toward the centre of the star releases gravitational energy, and this energy is enough to interrupt the star’s cooling process for billions of years.

“This is the first time this transport mechanism has been observed in any type of star, which is exciting, as it is not every day we uncover a whole new astrophysical phenomenon,” says Bédard, Research Fellow at the University of Warwick.

Why this happens in some stars and not others is uncertain, but Blouin thinks it is likely due to the composition of the star.

“Some white dwarf stars are formed by the merger of two different stars. When these stars collide to form the white dwarf, it changes the composition of the star in a way that can allow the formation of floating crystals,” says Blouin.

White dwarfs are routinely used as age indicators: the cooler a white dwarf is, the older it is assumed to be. However, due to the extra delay in cooling found in some white dwarfs, some stars of a given temperature may be billions of years older than previously thought.

“This new discovery will not only require that astronomy textbooks be revised but will also require that astronomers revisit the process they use to determine the age of stellar populations,” adds Blouin.

First Constraints on the Photon Coupling of Axionlike Particles from Multimessenger Studies of the Neutron Star Merger GW170817

by P. S. Bhupal Dev, Jean-François Fortin, Steven P. Harris, Kuver Sinha, Yongchao Zhang in Physical Review Letters

Neutron star mergers are a treasure trove for new physics signals, with implications for determining the true nature of dark matter, according to research from Washington University in St. Louis.

On Aug. 17, 2017, the Laser Interferometer Gravitational-wave Observatory (LIGO), in the United States, and Virgo, a detector in Italy, detected gravitational waves from the collision of two neutron stars. For the first time, this astronomical event was not only heard in gravitational waves but also seen in light by dozens of telescopes on the ground and in space.

Physicist Bhupal Dev in Arts & Sciences used observations from this neutron star merger — an event identified in astronomical circles as GW170817 — to derive new constraints on axion-like particles. These hypothetical particles have not been directly observed, but they appear in many extensions of the standard model of physics.

Axions and axion-like particles are leading candidates to compose part or all of the “missing” matter, or dark matter, of the universe that scientists have not been able to account for yet. At the very least, these feebly-interacting particles can serve as a kind of portal, connecting the visible sector that humans know much about to the unknown dark sector of the universe.

An artist’s rendition of our main idea. The ALP (dashed line), after being produced in the NS merger, escapes and decays outside the merger environment into photons, which can be detected by the *Fermi* satellite (or future MeV γ-ray telescopes).

“We have good reason to suspect that new physics beyond the standard model might be lurking just around the corner,” said Dev, first author of the study and a faculty fellow of the university’s McDonnell Center for the Space Sciences.

When two neutron stars merge, a hot, dense remnant is formed for a brief period of time. This remnant is an ideal breeding ground for exotic particle production, Dev said. “The remnant gets much hotter than the individual stars for about a second before settling down into a bigger neutron star or a black hole, depending on the initial masses,” he said.

These new particles quietly escape the debris of the collision and, far away from their source, can decay into known particles, typically photons. Dev and his team — including WashU alum Steven Harris (now NP3M fellow at Indiana University), as well as Jean-Francois Fortin, Kuver Sinha and Yongchao Zhang — showed that these escaped particles give rise to unique electromagnetic signals that can be detected by gamma-ray telescopes, such as NASA’s Fermi-LAT.

The research team analyzed spectral and temporal information from these electromagnetic signals and determined that they could distinguish the signals from the known astrophysical background. Then they used Fermi-LAT data on GW170817 to derive new constraints on the axion-photon coupling as a function of the axion mass. These astrophysical constraints are complementary to those coming from laboratory experiments, such as ADMX, which probe a different region of the axion parameter space.

In the future, scientists could use existing gamma-ray space telescopes, like the Fermi-LAT, or proposed gamma-ray missions, like the WashU-led Advanced Particle-astrophysics Telescope (APT), to take other measurements during neutron star collisions and help improve upon their understanding of axion-like particles.

“Extreme astrophysical environments, like neutron star mergers, provide a new window of opportunity in our quest for dark sector particles like axions, which might hold the key to understanding the missing 85% of all the matter in the universe,” Dev said.

Oriented Bedrock Samples Drilled by the Perseverance Rover on Mars

by Benjamin P. Weiss, Elias N. Mansbach, Joseph L. Carsten, et al in Earth and Space Science

As it trundles around an ancient lakebed on Mars, NASA’s Perseverance rover is assembling a one-of-a-kind rock collection. The car-sized explorer is methodically drilling into the Red Planet’s surface and pulling out cores of bedrock that it’s storing in sturdy titanium tubes. Scientists hope to one day return the tubes to Earth and analyze their contents for traces of embedded microbial life.

Since it touched down on the surface of Mars in 2021, the rover has filled 20 of its 43 tubes with cores of bedrock. Now, MIT geologists have remotely determined a crucial property of the rocks collected to date, which will help scientists answer key questions about the planet’s past.

In a study, an MIT team reports that they have determined the original orientation of most bedrock samples collected by the rover to date. By using the rover’s own engineering data, such as the positioning of the vehicle and its drill, the scientists could estimate the orientation of each sample of bedrock before it was drilled out from the Martian ground.

The results represent the first time scientists have oriented samples of bedrock on another planet. The team’s method can be applied to future samples that the rover collects as it expands its exploration outside the ancient basin. Piecing together the orientations of multiple rocks at various locations can then give scientists clues to the conditions on Mars in which the rocks originally formed.

“There are so many science questions that rely on being able to know the orientation of the samples we’re bringing back from Mars,” says study author Elias Mansbach, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences.
“The orientation of rocks can tell you something about any magnetic field that may have existed on the planet,” adds Benjamin Weiss, professor of planetary sciences at MIT. “You can also study how water and lava flowed on the planet, the direction of the ancient wind, and tectonic processes, like what was uplifted and what sunk. So it’s a dream to be able to orient bedrock on another planet, because it’s going to open up so many scientific investigations.”

Weiss and Mansbach’s co-authors are Tanja Bosak and Jennifer Fentress at MIT, along with collaborators at multiple institutions including the Jet Propulsion Laboratory at Caltech.

Examples of bedrock outcrops sampled by the Perseverance rover.

The Perseverance rover, nicknamed “Percy,” is exploring the floor of Jezero Crater, a large impact crater layered with igneous rocks, which may have been deposited from past volcanic eruptions, as well as sedimentary rocks that likely formed from long-dried-out rivers that fed into the basin.

“Mars was once warm and wet, and there’s a possibility there was life there at one time,” Weiss says. “It’s now cold and dry, and something profound must have happened on the planet.”

Many scientists, including Weiss, suspect that Mars, like Earth, once harbored a magnetic field that shielded the planet from the sun’s solar wind. Conditions then may have been favorable for water and life, at least for a time.

“Once that magnetic field went away, the sun’s solar wind — this plasma that boils off the sun and moves faster than the speed of sound — just slammed into Mars’ atmosphere and may have removed it over billions of years,” Weiss says. “We want to know what happened, and why.”

The rocks beneath the Martian surface likely hold a record of the planet’s ancient magnetic field. When rocks first form on a planet’s surface, the direction of their magnetic minerals is set by the surrounding magnetic field. The orientation of rocks can thus help to retrace the direction and intensity of the planet’s magnetic field and how it changed over time.

Since the Perseverance rover was collecting samples of bedrock, along with surface soil and air, as part of its exploratory mission, Weiss, who is a member of the rover’s science team, and Mansbach looked for ways to determine the original orientation of the rover’s bedrock samples as a first step toward reconstructing Mars’ magnetic history.

“It was an amazing opportunity, but initially there was no mission requirement to orient bedrock,” Mansbach notes.

Over several months, Mansbach and Weiss met with NASA engineers to hash out a plan for how to estimate the original orientation of each sample of bedrock before it was drilled out of the ground. The problem was a bit like predicting what direction a small circle of sheetcake is pointing, before twisting a round cookie cutter in to pull out a piece. Similarly, to sample bedrock, Perseverance corkscrews a tube-shaped drill into the ground at a perpendicular angle, then pulls the drill directly back out, along with any rock that it penetrates.

To estimate the orientation of the rock before it was drilled out of the ground, the team realized they need to measure three angles, the hade, azimuth, and roll, which are similar to the pitch, yaw, and roll of a boat. The hade is essentially the tilt of the sample, while the azimuth is the absolute direction the sample is pointing relative to true north. The roll refers to how much a sample must turn before returning to its original position.

In talking with engineers at NASA, the MIT geologists found that the three angles they required were related to measurements that the rover takes on its own in the course of its normal operations. They realized that to estimate a sample’s hade and azimuth they could use the rover’s measurements of the drill’s orientation, as they could assume the tilt of the drill is parallel to any sample that it extracts.

To estimate a sample’s roll, the team took advantage of one of the rover’s onboard cameras, which snaps an image of the surface where the drill is about to sample. They reasoned that they could use any distinguishing features on the surface image to determine how much the sample would have to turn in order to return to its original orientation.

In cases where the surface bore no distinguishing features, the team used the rover’s onboard laser to make a mark in the rock, in the shape of the letter “L,” before drilling out a sample — a move that was jokingly referred to at the time as the first graffiti on another planet. By combining all the rover’s positioning, orienting, and imaging data, the team estimated the original orientations of all 20 of the Martian bedrock samples collected so far, with a precision that is comparable to orienting rocks on Earth.

“We know the orientations to within 2.7 degrees uncertainty, which is better than what we can do with rocks in the Earth,” Mansbach says. “We’re working with engineers now to automate this orienting process so that it can be done with other samples in the future.”
“The next phase will be the most exciting,” Weiss says. “The rover will drive outside the crater to get the oldest known rocks on Mars, and it’s an incredible opportunity to be able to orient these rocks, and hopefully uncover a lot of these ancient processes.”

A post-merger enhancement only in star-forming Type 2 Seyfert galaxies: the deep learning view

by M S Avirett-Mackenzie, C Villforth, M Huertas-Company, S Wuyts, D M Alexander, S Bonoli, A Lapi, I E Lopez, C Ramos Almeida, F Shankar in Monthly Notices of the Royal Astronomical Society

When they are active, supermassive black holes play a crucial role in the way galaxies evolve. Until now, growth was thought to be triggered by the violent collision of two galaxies followed by their merger, however new research led by the University of Bath suggests galaxy mergers alone are not enough to fuel a black hole — a reservoir of cold gas at the centre the host galaxy is needed too.

The new study is believed to be the first to use machine learning to classify galaxy mergers with the specific aim of exploring the relationship between galaxy mergers, supermassive black-hole accretion and star formation. Until now, mergers were classified (often incorrectly) through human observation alone.

“When humans look for galaxy mergers, they don’t always know what they are looking at and they use a lot of intuition to decide if a merger has happened,” said Mathilda Avirett-Mackenzie, PhD student in the Department of Physics at the University of Bath and first author on the research paper. The study was a collaboration between partners from BiD4BEST (Big Data Applications for Black Hole Evolution Studies), whose Innovative Training Network provides doctorial training in the formation of supermassive black holes.

She added: “By training a machine to classify mergers, you get a much more truthful reading of what galaxies are actually doing.”

Supermassive black holes are found in the centre of all massive galaxies (to give a sense of scale, the Milky Way, with around 200 billion stars, is only a medium-sized galaxy). These supersized black holes typically weigh between millions and billions of times the mass of our sun. Through most of their lives, these black holes are quiescent, sitting quietly while matter orbits around them, and having little impact on the galaxy as a whole. But for brief phases in their lives (brief only on an astronomical scale, and most likely lasting millions to hundreds of millions of years), they use gravitation forces to draw large amounts of gas towards them (an event known as accretion), resulting in a bright disk that can outshine the entire galaxy.

It’s these short phases of activity that are most important for galaxy evolution, as the massive amounts of energy released through accretion can impact how stars form in galaxies. For good reason then, establishing what causes a galaxy to move between its two states — quiescent and star-forming — is one of the greatest challenges in astrophysics.

“Determining the role of supermassive black holes in galaxy evolution is crucial in our studies of the universe,” said Ms Avirett-Mackenzie.

For decades, theoretical models have suggested black holes grow when galaxies merge. However, astrophysicists studying the connection between galaxy mergers and black-hole growth over many years have been challenging these models with a simple question: How do we reliably identify mergers of galaxies?

Visual inspection has been the most commonly used method. Human classifiers — either experts or members of the public — observe galaxies and identify high asymmetries or long tidal tails (thin, elongated regions of stars and interstellar gas that extend into space), both of which are associated with galaxy mergers. However, this observational method is both time-consuming and unreliable, as it’s easy for humans to make mistakes in their classifications. As a result, merger studies often yield contradictory results.

For the new Bath-led study, the researchers set themselves the challenge of improving the way mergers are classified by studying the connection between black-hole growth and galaxy evolution through the use of artificial intelligence.

A pair of disc galaxies in the late stages of a merger. Credit: NASA.

They trained a neural network (a subset of machine learning inspired by the human brain and mimicking the way biological neurons signal to one another) on simulated galaxy mergers, then applied this model to galaxies observed in the cosmos. By doing so, they were able to identify mergers without human biases and study the connection between galaxy mergers and black-hole growth. They showed that the neural network outperforms human classifiers in identifying mergers, and in fact, human classifiers tend to mistake regular galaxies for mergers.

Applying this new methodology, the researchers were able to show that mergers are not strongly associated with black-hole growth. Merger signatures are equally common in galaxies with and without accreting supermassive black holes. Using an extremely large sample of approximately 8,000 accreting black-hole systems — which allowed the team to study the question in much more detail — it was found that mergers led to black-hole growth only in a very specific type of galaxies: star-forming galaxies containing significant amounts of cold gas. This shows that galaxy mergers alone are not enough to fuel black holes: large amounts of cold gas must also be present to allow the black hole to grow.

Ms Avirett-Mackenzie said: “For galaxies to form stars, they must contain cold gas clouds that are able to collapse into stars. Highly energetic processes like supermassive black-hole accretion heats this gas up, either rendering it too energetic to collapse or blowing it out of the galaxy.”
She added: “On a clear night, you can just about spot this process happening in real time with the Orion Nebula — a large, star-forming region in our galaxy and the closest of its kind to Earth — where you can see some stars that were formed recently and others that are still forming.”
Dr Carolin Villforth, senior lecturer in the Department of Physics and Ms Avirett-Mackenzie’s supervisor at Bath, said: “Until now, everyone was studying mergers the same way — through visual classification. With this method, when using expert classifiers that can spot more subtle features, we were only able to look at a couple of hundred galaxies, no more.
“Using machine learning instead opens up an entirely new and very exciting field where you can analyse thousands of galaxies at a time. You get consistent results over really large samples, and at any given moment, you can look at many different properties of a black hole.”