Saturday, February 25, 2023

Webb telescope spots super old, massive galaxies that shouldn’t exist


Here we make use of the 1-5 μm coverage of the JWST early release observations to search for intrinsically red galaxies in the first ≈ 750 million years of cosmic history. In the survey area, we find six candidate massive galaxies (stellar mass > 1010 solar masses) at 7.4 ≤ z ≤ 9.1, 500–700 Myr after the Big Bang, including one galaxy with a possible stellar mass of ~1011 solar masses.

If verified with spectroscopy, the stellar mass density in massive galaxies would be much higher than anticipated from previous studies based on rest-frame ultraviolet-selected samples.

They posit two scenarios:

We infer that the possible interpretation of these JWST-identified “optical break galaxies” falls between two extremes. If the redshifts and fiducial masses are correct, then the mass density in the most massive galaxies would exceed the total previously estimated mass density...

The other extreme interpretation is that all the fiducial masses are larger than the true masses by factors of >10-100.

It will be extremely exciting to see if these mass density estimates are validated.

CU Boulder:

In a new study, an international team of astrophysicists has discovered several mysterious objects hiding in images from the James Webb Space Telescope: six potential galaxies that emerged so early in the universe’s history and are so massive they should not be possible under current cosmological theory.

“It’s bananas,” said Erica Nelson, co-author of the new research and assistant professor of astrophysics at CU Boulder. “You just don’t expect the early universe to be able to organize itself that quickly. These galaxies should not have had time to form.”

She explained that in astronomy, red light usually equals old light. The universe, Nelson said, has been expanding since the dawn of time. As it expands, galaxies and other celestial objects move farther apart, and the light they emit stretches out—think of it like the cosmic equivalent of saltwater taffy. The more the light stretches, the redder it looks to human instruments. (Light from objects coming closer to Earth, in contrast, looks bluer)...The team ran calculations and discovered that their old galaxies were also huge, harboring tens to hundreds of billions of sun-sized stars worth of mass, on par with the Milky Way.


While scanning a region of the cosmos near the Big Dipper, a group of astronomers identified six faint objects as they appeared well over 13 billion years ago. They suspect the objects are ancient galaxies. Scientists expect such early collections of stars and swirling matter to be relatively small. After all, such galaxies hadn't had much time to form or grow. But these galaxies are giants, the researchers report.

"If even one of these galaxies is real, it will push against the limits of our understanding of cosmology,” Nelson noted.


Chrome 110 will automatically discard background tabs


Heads up, everybody: Chrome will start doing stuff to your permanently open tabs. Chrome version 110 is rolling out now, and on Windows, macOS, and Linux, the release comes with the new "Memory Saver" feature that will be automatically enabled. We first wrote about this when it hit the Chrome nightly build "Canary Channel" in December, but now the feature is rolling out to everyone.

Google's explanation of the feature says, "When a tab is discarded, its title and favicon still appear in the tab strip but the page itself is gone, exactly as if the tab had been closed normally. If the user revisits that tab, the page will be reloaded automatically."

The feature is broadly similar to Edge's "sleeping tabs".

Digital Trends

First leaked in version 108, Memory Save and Energy Saver are the latest utilities rolling out globally to Chromebook, Mac, and Windows users right now. The rollout is gradual, so you may not see the update on your device(s) yet.

Memory Saver is touted to save up to 30% more RAM, by freeing up memory from inactive tabs. If the utility identifies an idling tab, it will put it in stasis, thus freeing up resources. If and when you revisit that tab, Chrome refreshes it as needed. 

Tuesday, February 21, 2023

Biden declines to veto Apple Watch ban

The Hill:

President Biden has upheld an International Trade Commission (ITC) ruling that could result in an import ban on the Apple Watch, according to AliveCor, a medical device company that has accused Apple of patent infringement.

The administration’s decision to uphold a potential ban on imports of the tech product sets the stage for a high-stakes legal battle.

Following the most recent ITC ruling, Apple hired the former chairwoman of the ITC to lobby on its behalf, in an apparent effort to secure a presidential veto. 

The dispute dates back to 2018, when Apple launched Apple Watch models with built-in electrocardiogram sensors, forcing AliveCor to cancel sales of its heart monitoring accessory. AliveCor said that it first shared its technology with Apple in 2015 in an effort to secure a partnership.

The Verge:

“We applaud President Biden for upholding the ITC’s ruling and holding Apple accountable for infringing the patents that underpin our industry-leading EKG technology,” AliveCor CEO Priya Abani said in a statement sent to The Verge.

Back in December, the ITC issued a final determination that Apple had infringed on AliveCor’s wearable EKG tech. If enforced, that would mean that Apple would no longer be able to import Apple Watch with EKG capabilities into the US for sale.

Biden’s decision doesn’t mean every Apple Watch from the Series 4 to the Apple Watch Ultra (excluding both generations of the SE) is about to disappear off shelves.

However, AliveCor isn’t the only medical tech company that’s seeking an import ban on the Apple Watch via the ITC. Masimo also sued Apple for allegedly infringing on five of its pulse oximetry patents.

That lawsuit is also still in the works but recently an ITC judge ruled in Masimo's favor.


The Biden administration on Tuesday declined to overrule a US International Trade Commission decision that the Apple Watch had infringed health monitoring patents from medical device company AliveCor. As a result, the tech giant could face an import ban of its infringing Apple Watches, depending on how appeals work out.

Apple, for its part, said in December that it expects to prevail in the case because AliveCor's patents had been found invalid. It plans to appeal the ITC's decision to federal court. 

Systematic Near-Infrared Follow-up of Type Ic-BL Supernovae

Came across this interesting paper on the arXiv focusing on Type Ic-BL supernovae and their ability to produce rapid neutron-capture process (r-process) material. Also, they performed their photometric follow-up using the Las Cumbres Observatory, which is pretty neat!


We present the first systematic study of 25 SNe Ic-BL -- discovered with the Zwicky Transient Facility and from the literature -- in the optical/near-infrared bands to determine what quantity of r-process material, if any, is synthesized in these explosions. Using semi-analytic models designed to account for r-process production in SNe Ic-BL, we perform light curve fitting to derive constraints on the r-process mass for these SNe. We also perform independent light curve fits to models without r-process. 

Most of the SNe in our sample show no compelling evidence for r-process production. In our model fits, the general trend we observe is that the best fit consistently under-predicts the peak of the optical light curve, while performing better at predicting the NIR flux. In some cases, the under-prediction is egregious, while in other cases it is more modest. In general under-prediction indicates that the optical-NIR color of the SN is actually bluer than predicted by the models, providing stronger evidence towards favoring r -process-free models over the enriched models.

There is still potentially a link between r-process material and GRBs, but this study was unable to probe it due to the nature of the sample used. 

The fact that none of these SNe are linked to standard, classical long GRBs prevents us from exploring the proposed theoretical connection between the GRB energetics and r -process production. If the GRB jet energy, which scales with the mass accreted by the disk, correlates with the amount of r -process mass produced in the disk winds, then collapsars with no GRBs may not be able to produce detectable r-process signatures.

The work has a few important caveats as well.

First, we note that the r-process enriched and r-process-free models make different predictions about the relationship between nickel mass and SN luminosity...As a result, the amounts of nickel inferred by each model for a given luminosity are inconsistent.

Furthermore, differences between kilonovae and r -process-enriched SN (e.g., in their densities or their compositions) may mean that nebular-phase emission from the former is not a perfect predictor of nebular phase emission from the latter. 

Finally, we acknowledge the limitations of the dataset we present here for testing whether collapsars synthesize r -process elements. Due to the nature of our classical observing runs with WIRC, our NIR light curves are very sparse, and in some cases our upper limits are too shallow to be constraining.

Overall, an exciting paper. Type II/Ib/Ic supernovae have long been potential candidates for detection of prominent r-process influence. This fairly comprehensively presents a case to exclude SNe Type Ic from consideration. 

Monday, February 20, 2023

Enshittification and Meta, Twitter, Bing


Twitter Blue is an opt-in, paid subscription that adds a blue checkmark to your account and offers early access to select features, like Edit Tweet.

Twitter Blue subscribers who joined for $7.99 on iOS will be notified by Apple that their subscription will be automatically renewed for $11/month (or your local pricing) unless they choose to cancel their subscription.

Those who initially subscribed on iOS for $2.99 or $4.99/month will need to upgrade their subscription for $8/month or $84/year on web or $11/month on iOS (or the local pricing), or lose their subscription.

Mark Zuckerberg (via Facebook):

This week we're starting to roll out Meta Verified -- a subscription service that lets you verify your account with a government ID, get a blue badge...Meta Verified starts at $11.99 / month on web or $14.99 / month on iOS.

This is clearly inspired by Twitter's "Twitter Blue"; however, I wonder how much of this decision was driven by the need for extra revenue now that Apple is attempting to choke off some of Meta's ad revenue.

Juli Clover (via Michael Tsai):

Instagram and Facebook are monetized through advertising at the current time, but changes like Apple’s App Tracking Transparency can make ads an unreliable revenue stream. Subscription payments will give Facebook a steady monthly income.

Twitter has also removed the free tier of their API access--a feature used by thousands of developers to make excellent and low-cost apps.  


A week after Twitter made the announcement about shutting down free access to the API, the company said today that it will charge $100 per month for the basic tier of API. This will get developers access to a “low level of API usage” — without specifying what that exactly means — and the Ads API.

Last week’s announcement drew a lot of criticism from developers — especially folks who made fun bots posting information or pictures. 

Apart from this, people have also pointed out that engineers building solutions for natural disasters like earthquakes also rely on Twitter API. So discontinuing the free tier will affect those solutions.

Akin Unver (via Twitter):

Couldn't come at a worse time. Most analysts and programmers that are building apps and functions for Turkey earthquake aid and relief, and are literally saving lives, are reliant on Twitter API. Any limit/structure/architecture change will make everyone's life difficult.

Microsoft saw this and followed suit:


The existing Microsoft Bing Search APIs will increase in price effective May 1, 2023. The price increase will apply to all markets.


Today, Microsoft sent shockwaves to the developers who rely on Microsoft Bing Search APIs by announcing price increase. This is not a usual nominal price increase update. With the new changes, pricing of some of the APIs have gone up to 10x. Yes, 10x.

Optional Bing Statistics Add-in which used to cost $1 per 1,000 transactions will now cost $10 per 1,000 transactions.

The above pricing equates to $0.028/query for less than 1M requests/day and a whopping $.20/query for over 1M requests/day. 

I spend a lot of time working with both free and paid APIs, I genuinely can't remember ever seeing one with $0.20 per query on any tier. That would be a completely prohibiting price tier for an independent developer, or developers providing a primarily free service. 

Michael Tsai

This sounds like a problem for DuckDuckGo and other search engines that rely on Bing, unless they have special long-term deals.

Cory Doctorow has a fantastic blog post about "enshittification," a term he coined describing how platforms crumble after locking in customers with appealing services before abusing them to milk every last ounce of profit, rendering the service unusable. Watching Meta, Twitter, and Bing riff terrible anti-customer ideas off of each other is very reminiscent of this.

Sunday, February 19, 2023

SWPC Reports X-Class Solar Flare

Solar Weather Prediction Center

An X2.2/2b flare (R3) occurred late on February 17. The flare peaked Feb 17 15:16 ET. Effects: temporary degradation or complete loss of high-frequency radio signals on some of the sunlit side of the Earth.


Solar flares are powerful bursts of energy. Flares and solar eruptions can impact radio communications, electric power grids, navigation signals, and pose risks to spacecraft and astronauts. This flare is classified as an X2.2 flare.  X-class denotes the most intense flares, while the number provides more information about its strength.

According to the SWPC, the geomagnetic storm may affect satellite operations and could even lead to weak power-grid fluctuations. In addition, migratory animals could be affected, and the Northern Lights may be visible farther south than usual, like in northern Michigan and Maine.

A G2-level solar storm could affect high-latitude power systems by triggering voltage alarms, and long-duration storms could cause damage to transformers. In addition, corrective actions may be necessary for spacecraft orbiting Earth.

HaloCME (via Twitter):

I love this!  Highly eruptive X2.2 flare with a nice coronal wave, although I doubt the CME will even glance Earth. 

HaloCME has a fantastic visualization in that tweet. 

Man beats machine at Go in human victory over AI


A human player has comprehensively defeated a top-ranked AI system at the board game Go, in a surprise reversal of the 2016 computer victory that was seen as a milestone in the rise of artificial intelligence.

The triumph, which has not previously been reported, highlighted a weakness in the best Go computer programs that is shared by most of today’s widely used AI systems, including the ChatGPT chatbot created by San Francisco-based OpenAI.

The tactics that put a human back on top on the Go board were suggested by a computer program that had probed the AI systems looking for weaknesses. The suggested plan was then ruthlessly delivered by Pelrine.

This approach to identifying flaws in LeelaZero and similar networks strongly reminds me of a generative adversarial neural network, where networks are pitted against each other in a zero-sum game. I really believe this approach will represent the next big step forward for AI; neural networks that only require an objective function and initial conditions, while all the normal fine-tuning that typically has to be done by humans will be handled by automated GANs. 

Bojan Tunguz (via Twitter):

Very interesting story. It seems that we can still beat AIs, but we’d need the help of another AI to teach us how.

Build-up to the Apple Watch ban decision


Last month an International Trade Commission (ITC) judge ruled that Apple infringed on a patent owned by medical device maker AliveCor with the blood oxygen feature on the Apple Watch. 

While Apple was cleared of infringing on four other AliveCor patents, the one patent that Apple got busted for using without permission could lead to an import ban that would block shipments of the Apple Watch from entering the U.S.


Back in 2015, right after Apple Watch was released, AliveCor created a special Apple Watch band with ECG sensors to showcase the potentials of this technology. The company even shared the technology with Apple hoping to secure a partnership agreement.

However, that partnership never happened, and in 2018 Apple introduced Apple Watch Series 4 with its own ECG sensor built into the watch.

Apple (via 9to5Mac):

At Apple, our teams work tirelessly to create the best products and services in the world, with technology that empowers users with industry-leading health, wellness and safety features. While we firmly disagree with the ITC’s decision today, we are pleased that the exclusion order has been put on pause, consistent with past precedent. The patents on which AliveCor’s case rest have been found invalid, and for that reason, we should ultimately prevail in this matter.

The Hill:

Apple is boosting its lobbying might as President Biden nears a decision next week on whether to block a potential Apple Watch ban. The apparent effort to win over the White House is the latest lobbying push by Apple, which leans on former congressional staffers and federal officials to relay its message in the nation’s capital. “Apple has unlimited resources. They’re gonna go after everyone they can get and that’s what they’re doing,” said Priya Abani, CEO of AliveCor. “We are just a startup.”

The Mountain View, Calif., startup, which employs around 150 people, first shared its wearable electrocardiogram (ECG) sensor with Apple in 2015. AliveCor told The Hill that it believed that it had a good relationship with the Silicon Valley giant and went on to sell an ECG accessory for the Apple Watch. But in 2018, Apple launched an Apple Watch with a built-in ECG sensor and made third-party heart monitoring software incompatible with the product, forcing AliveCor to cancel sales of its product.

Various app developers and startups have accused Apple of “Sherlocking,” where the Silicon Valley giant monitors an innovative technology, then copies it once the use case is demonstrated, rather than pay startups to license their technology. 

If Biden upholds the ITC ruling, litigation would continue, while a veto would ensure that an Apple Watch ban will not take place. Startups are closely watching Biden’s decision, given that the president has railed against powerful companies for using their market dominance to crush competition, Abani said.

An Earth-sized Planet around an M5 Dwarf Star at 22 pc

 arXiv (accepted for publication in AJ):

We report on the discovery of an Earth-sized transiting planet (Rp=1.015±0.051R⊕) in a P=4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc.

Combining the light curves with the data secured by our follow-up observations including high-resolution imaging and near infrared spectroscopy with IRD, we rule out false positive scenarios, finding a low false positive probability of 2×10−4. Based on IRD’s radial velocities of K2-415, which were sparsely taken over three years, we obtain the planet mass of 3.0 ± 2.7 M⊕ (Mp < 7.5 M⊕ at 95 % confidence) for K2-415b. Being one of the lowest mass stars (≈ 0.16 M ) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.

Figure 1. Light curves of K2-415 obtained by K2 (top; K2SFF) and TESS (bottom; PDC-SAP). Those data were taken at long (≈ 29 minutes) and short (2 minutes) cadences for K2 and TESS light curves, respectively. The red solid line in each panel represents the GP regression to the observed light curve (see Section 4.4).

"The K2-415 system is unique in that K2-415 is one of the coolest, or lowest-mass, stars known to host an exoplanet," Teruyuki Hirano of the Graduate University for Advanced Studies (SOKENDAI) in Japan, lead author on a paper about the discovery, told

"One motivation for investigating the planets around such low-mass stars is to understand and clarify whether those planets form and evolve just like the planets around solar-type stars," said Hirano. 

Friday, February 17, 2023

Observational Evidence for Cosmological Coupling of Black Holes and its Implications for an Astrophysical Source of Dark Energy

This series of papers are very interesting. The results are a two-part series published in ApJ

The Astrophysical Journal:

The assembly of stellar and supermassive black hole (SMBH) mass in elliptical galaxies since z ∼ 1 can help to diagnose the origins of locally observed correlations between SMBH mass and stellar mass.

Using a Bayesian analysis framework, we find evidence for translational offsets in both stellar mass and SMBH mass between the local sample and both higher-redshift samples.

We conclude that either there is a physical mechanism that preferentially grows SMBHs in elliptical galaxies at z ≲ 2, or that selection and measurement biases are both underestimated, and depend on redshift.

The Astrophysical Journal (via arXiv):

The Kerr black hole solution is, however, provisional as its behavior at infinity is incompatible with an expanding universe. Black hole models with realistic behavior at infinity predict that the gravitating mass of a black hole can increase with the expansion of the universe independently of accretion or mergers, in a manner that depends on the black hole’s interior solution. We test this prediction by considering the growth of supermassive black holes in elliptical galaxies over 0 < z ≲ 2.5. We find evidence for cosmologically coupled mass growth among these black holes, with zero cosmological coupling excluded at 99.98% confidence.

We thus propose that stellar remnant black holes are the astrophysical origin of dark energy, explaining the onset of accelerating expansion at z ∼ 0.7.

These results are astonishingly consistent with current theoretical prediction for this kind of empirical analysis. But reading the second paper, I'm left a little confused by the nature of the coupling, and whether or not a viable physical mechanism exists within our current understanding.

We show that k = 3 stellar remnant BHs produce the measured value of ΩΛ within a wide range of observationally viable cosmic star formation histories, stellar IMFs, and remnant accretion. They remain consistent with constraints on halo compact objects and they naturally explain the “coincidence problem,” because dark energy domination can only occur after cosmic dawn. Taken together, we propose that stellar remnant k = 3 BHs are the astrophysical origin for the late-time accelerating expansion of the universe.

But a team of 17 international researchers led by the University of Hawaii has discovered the first evidence for the origin point of dark energy: Black holes.

The idea that black holes are a source of dark energy isn't new. In fact, it's part of Einstein's theory of general relativity. But this is the first time astronomers have obtained observational evidence to support the theory. 

The Guardian

Instead of dark energy being smeared out across spacetime, as many physicists have assumed, the scientists suggest that it is created and remains inside black holes, which form in the crushing forces of collapsing stars.

“We propose that black holes are the source for dark energy,” said Duncan Farrah, an astronomer at the University of Hawaii. “This dark energy is produced when normal matter is compressed during the death and collapse of large stars.”

The claim was met with raised eyebrows from some independent experts, with one noting that while the idea deserved scrutiny, it was far too early to link black holes and dark energy. “There’s a number of counter-arguments and facts that need to be understood if this claim is going to live more than a few months,” said Vitor Cardoso, a professor of physics at the Niels Bohr Institute in Copenhagen.

Vitor is a brilliant guy--I'm very curious to hear more of his thoughts as the theory gets tested more in the academic community.

“The importance of this work is that it’s taken the theories about black holes with dark energy cores and linked them for the first time to tangible observations of the universe,” said Chris Pearson, a co-author on the study and Astronomy Group Leader at STFC RAL Space in Oxfordshire. “These black holes are expected to grow in mass as the universe expands.”

But far more work is needed before it will gain acceptance. Among many questions remaining is how black holes can pull everything nearby towards them while simultaneously driving the universe apart.

Feels like a critical question there. A lot of scientists seem to be skeptical specifically because there doesn't seem to be a fundamental mechanism proposed for the cosmic coupling.

Ethan Siegel (via BigThink):

Which is why it was an absolute shock to see the headline appear, just days ago, that “Black holes are the source of dark energy.” Even more surprisingly — at least, to me — was that when I went into the scientific paper itself, this was based not on a theoretical calculation, but rather on observational evidence, which was absolutely shocking to see. The overall claim is that black holes, and specifically, supermassive black holes, couple to the Universe’s expansion on the largest cosmic scales, and that the specific way that they must couple could potentially explain some or even all of the dark energy effects we observe.

How do you do this? The approach the authors take is as follows.

They look at multiple samples of elliptical galaxies from across cosmic time: nearby (modern) galaxies, galaxies from ~6.6 billion years ago, galaxies from ~7.2 billion years ago, and galaxies from ~9.6 billion years ago.

They assume that there’s a universal relationship between the mass of the central black hole and the mass of the stars within a galaxy, which can evolve over cosmic time but should be universal at any particular time.

Then, they use their model of “cosmological coupling,” assuming there exists a relationship between the mass of a black hole at any particular cosmic time (or, more accurately, redshift) and the mass of the black hole at the time it “becomes cosmically coupled” to the expansion rate, to determine whether (and, if so, how) the coupling parameter, k, has the same value across cosmic time...if k = 3, then the coupling is at the maximum allowable value, and the mass of the black hole increases as the cube of the redshift ratio, and the black hole acts like it causes dark energy.

They find k=3 to a 3-sigma confidence level, and rule out the "default" k=0 case with a 99.98% certainty. Ethan is unconvinced, however, as they fail to put forth a meaningful mechanism as to how black holes grow and evolve over cosmic time.

But I think the default assumption should be that these black holes are really just behaving as any other mass in the Universe behaves, and that this empirical approach of “We’re going to measure the masses of supermassive black holes and stars in elliptical galaxies and use that to infer the cosmological coupling” totally glosses over the big astrophysics question that should be investigated: how do these black holes grow and evolve over cosmic time? Until you know that answer, you’re attributing a measured effect to what might be entirely the wrong cause.

Sabine Hossenfelder (via Twitter):

Yes, I've seen the headlines saying that black holes may be dark energy.  I think that's extremely implausible. First of all, the statement is immediately contradictory because what we mean by "dark energy" is defined by having a particular equation of state. A collection of black holes does not have the right equation of state, so it can't be dark energy. 

Then they say, we ASSUME that this extra growth comes from a cosmological source. And then there's some bla-bla about pressure and energy conservation saying that therefore it needs to be a type of dark energy. I can't follow the argument.

This means the argument in the paper basically comes down to saying: We have two things that we don't understand (a) growth of supermassive black holes and (b) the origin of dark energy. We assume they're linked and if we assume they're linked the stat significance is high.

To say the hopefully obvious, assuming that two things are related doesn't show they're related. 

Her interview about physics as a religion under the guise of mathematics was a very fun read. I'll keep updating this post with qualified opinions I run across, and my own thoughts as I get a better look at the papers.

(Updates to original post below)

If true, the connection would link two of the most mind-bending concepts in physics—black holes and dark energy—and suggest that the source of the latter has been under theorists’ noses for decades. However, some leading theorists are deeply skeptical of the idea.

“What they are proposing makes no sense to me,” says Robert Wald, a theoretical physicist at the University of Chicago who specializes in Albert Einstein’s general theory of relativity, the standard understanding of gravity.

Wald is unpersuaded. He questions how an orb of pure dark energy could be stable. He also says the numbers don’t seem to add up: Dark energy is known to make up 70% of the mass-energy of the universe, whereas black holes are a mere fraction of the ordinary matter, which constitutes less than 5% of the universe. “I don't see how it is in any way conceivable that such objects could be relevant to the observed dark energy,” he says.

Bob Wald not being on board is a pretty bad sign. I learned (as did many other students) general relativity from his classic texts. He is pretty broadly considered a leading expert in the field.

Other theorists were more receptive to the radical claim—even if it ends up being wrong. “I’m personally excited about it,” says astrophysicist Niayesh Afshordi of the Perimeter Institute for Theoretical Physics.

Nevertheless, Afshordi is supportive of efforts to rethink fundamental assumptions about the universe. “Most new theoretical ideas are dismissed by skepticism,” he says. “But if we dismiss all the new ideas then there won’t be anything left.”

This is an excellent point. Even if this proposed idea it ends up being incorrect, it has raised an incredibly interesting question about a particular subset of black holes. The black holes examined in the Farrah et al. dataset were chosen to be black holes who would have relatively constant mass over the eons. But a clear non-constant relationship is found in their distribution function. Even if these black holes are not dark energy as the paper proposes, what causes this? The article summarizes this but doesn't actually ask this question:

To test this possibility, Farrah and his colleagues studied elliptical galaxies, which contain black holes with millions or billions of times the Sun’s mass in their centers. They focused on galaxies with little gas or dust floating around between their stars, which would provide a reservoir of material that the central black hole could feed on. Such black holes wouldn’t be expected to change much over the course of cosmic history.

Yet by analyzing the properties of ellipticals over roughly 9 billion years, the team saw that black holes in the early universe were much smaller relative to their host galaxy than those in the modern universe, indicating they had grown by a factor of seven to 10 times in mass, Farrah and colleagues reported this month in the Astrophysical Journal.

Assuming this isn't the result of dark energy as the study proposes, it's still a compelling mystery. To our understanding, these black holes shouldn't be growing, and yet they did--by an order of magnitude in some cases. 

Oxford Student:

This evidence may appear strong, but the physics community is not wholly convinced. Dr Chris Pearson, a co-author of the study, stated “If the theory holds, this is going to revolutionise the whole of cosmology.” Pearson is a researcher at the Rutherford Appleton Laboratory, located just outside of Oxford.  Other cosmologists are taking a more measured approach, waiting for “a lot more evidence” before fully committing to the idea. Theoretical physicists feel that this does not quite solve the mystery, with concerns about how the proposed “ball of dark energy” could remain stable (i.e not explode, collapse, or otherwise become something else). It is clear that there is more work to be done, but this could be the beginning of something very exciting.


At the risk of repeating the overused adage, “extraordinary claims require extraordinary evidence.” The ability to verify results repeatedly is one of the most important qualifiers for evidence to be considered sound. In other words, results must be demonstratable again and again and (preferably) using varying methods. The authors acknowledge this and hope that repeated observations will bear them out. But for the time being, the claim they’ve made remains extraordinary and (given the implications) demands further investigation.

PhysicsWorld (linked here):

The new theory hasn’t passed without controversy in physics circles, with many researchers unwilling to accept this cosmological coupling just yet.

“I can spot things that are troubling,” Universidad ECCI cosmologist Luz Ángela García tells Physics World. “Saying that their observation sets evidence for black holes being made out of dark energy seems like a long shot, in particular, because we cannot perform measurements ‘inside’ the black hole.”

García is also troubled by the fact that by linking dark energy to black holes, the team’s theory connects this force to the life cycle of stars, describing it as “very risky”. This is because when scientists consider the energy–matter content of the universe, black holes and thus dark energy in this model have already been accounted for in the 5% “ordinary matter” proportion of the energy–matter content of the universe.

Finally, García notes that the timeline of the universe leaves a gap of two billion years that the team’s theory struggles to fill.

“The peak of the number of black holes and quasars coincides with the peak of the star formation history approximately 10 billion years ago, and after that there’s a rapid decline in the number of these massive objects,” she explains. “On the other hand, the kickstart of the dark-energy domination occurs more or less eight billion years ago.”

This article has a quote from Dr. Farrah regarding the "controversy":

Farrah himself concurs that the mystery of dark energy is far from solved, acknowledging that while the two papers provide evidence of an astrophysical source for dark energy, their argument needs much more scrutiny.

“Dark energy remains a deeply mysterious phenomenon,” Farrah concludes. “I would say our papers raise the possibility of black holes as a source for dark energy and provide an ‘interesting hypothesis’, but at present, no more than that.”

I put "controversy" in quotes because while there is a lot of disagreement in the community about the validity of the theory, "controversy" has a very gross inappropriate drama-esque association with it. Fundamentally, nothing about the paper is inappropriate or "controversial" in this sense. Farrah and his team split the work into two distinct volumes; the first providing a solid report on an exciting data analysis, leaving 100% of the interpretation for the second volume. Do you notice how no one is casting much doubt on the first of the papers? It's because their actual data analysis is excellent; it's the interpretation scientists are disagreeing on. Farrah recognizes this himself in his quotes and interviews. Not only was it a smart thing to do (to avoid any "guilt by association" with the data analysis), it was also (in my opinion) a very responsible thing to do. The data are untainted by the interpretation, and the interpretation is not lent undue credibility by the solid data analysis.

Wednesday, February 15, 2023

Spherical symmetry in the kilonova AT2017gfo/GW170817

 Nature (via arXiv):

The mergers of neutron stars expel a heavy-element enriched fireball which can be observed as a kilonova. The kilonova's geometry is a key diagnostic of the merger and is dictated by the properties of ultra-dense matter and the energetics of the collapse to a black hole. 

We conclude that energy injection by radioactive decay is insufficient to make the ejecta spherical. A magnetar wind or jet from the black hole disk could inject enough energy to induce a more spherical distribution in the overall ejecta, however an additional process seems necessary to make the element distribution uniform.

Kilonovae are one of few objects that allow a relatively direct asymmetry measurement, via the expanding photospheres method. Normally, this method uses information about the expanding photosphere to fix the distance; however, since we can measure the explosion time very precisely from the gravitational wave, and we know the distance fairly accurately by measuring the distance to the host galaxy, we can use this method to work backwards to measure a transverse velocity of the ejecta. Comparing the two velocities gives a direct measurement of the asymmetry of the expansion.

For every epoch we find a line shape that is consistent with a completely spherical expansion to within a few percent. These line-shape constraints are independent of the EPM measurements and verify the spherical nature of the kilonova at early epochs. 

This is pretty interesting. Current GRMHD simulations show that asymmetry is usually favored in explosions like these. Spherical symmetry is of course possible, but it is not a generic attribute, and we would not expect to see it very frequently. Understanding what kind of mechanism could generate spherical symmetry in an explosion that is typically asymmetric is an important problem.

Energy may also be injected in an anisotropic fashion as a relativistic wind from the remnant neutron star or black hole by tapping the rotational energy of the system. Within the first few seconds of the explosion a polar outflow could be launched and produce a rapidly-expanding balloon of high-Ye material with low opacity, dominated by elements like Sr. This polar outflow, outpacing the equatorial ejecta, would expand sideways, covering the low-Ye material and providing a near-spherical kilonova.


The colossal explosion resulting from a merger between two neutron stars has an unexpectedly perfect shape...The spherical explosion they actually found suggests that our understanding of neutron star mergers is lacking.

"You have two super-compact stars that orbit each other 100 times a second before collapsing. Our intuition, and all previous models, say that the explosion cloud created by the collision must have a flattened and rather asymmetrical shape," Sneppen says.

"The most likely way to make the explosion spherical is if a huge amount of energy blows out from the center of the explosion and smooths out a shape that would otherwise be asymmetrical. So the spherical shape tells us that there is probably a lot of energy in the core of the collision, which was unforeseen."

However, this theory does not explain another aspect of the researchers' discovery. According to the previous models, while all elements produced are heavier than iron, the extremely heavy elements, such as gold or uranium, should be created in different places in the kilonova than the lighter elements such as strontium or krypton, and they should be expelled in different directions. The researchers, on the other hand, detect only the lighter elements, and they are distributed evenly in space.

They therefore believe that the enigmatic elementary particles, neutrinos, about which much is still unknown, also play a key role in the phenomenon.


Tuesday, February 14, 2023

Zero-day Webkit vulnerability (CVE-2023-23529) affecting Apple ecosystem


Apple on Monday announced the release of updates for macOS, iOS and Safari, and they all include a WebKit patch for a new zero-day vulnerability tracked as CVE-2023-23529.

In response to these types of attacks, Apple last year announced Lockdown Mode, a feature that should significantly limit the ability to use sophisticated exploits against its customers. 


Impact: Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.


WebKit flaws are also notable for the fact that they impact every third-party web browser that's available for iOS and iPadOS owing to Apple's restrictions that require browser vendors to use the same rendering framework.

Also addressed by the company is a use-after-free issue in the Kernel (CVE-2023-23514) that could permit a rogue app to execute arbitrary code with the highest privileges.

Credited with reporting the issue are Xinru Chi of Pangu Lab and Ned Williamson of Google Project Zero. Apple said it resolved the vulnerability with improved memory management.

The updates are available for the following devices:

  • iPhone 8 and later, iPad Pro (all models), iPad Air 3rd generation and later, iPad 5th generation and later, and iPad mini 5th generation and later
  • Macs running macOS Ventura, macOS Big Sur, and macOS Monterey\
From a message I received from my institution:
Apple released emergency security updates on Monday 02/13/2023 to address (among other things) a zero-day vulnerability tracked as CVE-2023-23529, which pertains to a WebKit confusion issue that could be exploited to trigger OS crashes and gain code execution on compromised devices.

Carbonaceous dust grains within galaxies seen in the first billion years of cosmic time


Interstellar dust captures a significant fraction of elements heavier than helium in the solid state and is an indispensable component both in theory and observations of galaxy evolution. However, the astrophysical origin of various types of dust grains remains an open question, especially in the early Universe. Here we report direct evidence for the presence of carbonaceous grain from the detection of the broad UV absorption feature around 2175 Å in deep near-infrared spectra of galaxies up to the first billion years of cosmic time, at a redshift (𝑧) of ∼ 7. 

Our results suggest a more rapid production scenario, likely in supernova (SN) ejecta.

The previous scenario considered was giant branch/AGB stellar evolution. There are some issues with the supernova scenario, particularly in that supernova shock waves tend to vaporize surrounding dust grains produced in previous phases.

Figure 1. Spectrum taken by JWST/NIRSpec of JADES-GS-z6-0 at redshift z = 6.71. a...

I like this figure a lot--it shows the UV bump around 2000 Å extremely clearly.

The holding call against James Bradberry in Super Bowl LVII

The Ringer:

The call, which was probably technically correct yet exasperatingly and incongruously ticky-tacky (more on that later), caused a furor both in the stadium and on social media and gave Kansas City a new set of downs. That put the Chiefs back into command, and after subsequently rebuffing the Eagles’ invitation to waltz into the end zone untouched (a ploy that would have at least given Philly the chance to counter), Kansas City kneeled the ball twice, ran the clock down to 11 seconds, and kicked the championship-sealing field goal.

By the letter of the law, it was probably the correct call. And Bradberry even admitted after the game that he tugged on Smith-Schuster’s jersey. But in a critical moment like that, in a game in which referees had been consistently allowing corners a little extra contact and more latitude for physicality (see: a first-quarter third-down throw to Smith-Schuster in which the refs allowed even heavier contact from the defender), it felt like a fickle overreach. It was literally the only holding call in the game, by either team.

There were a lot of things that played into this call. First and fundamentally, it was a correct call:

Pete Scantlebury (Twitter):

Find it very weird that neither Burkhardt nor Olsen were talking about this moment with the hold. Pereira mentioned it but they seemed to brush it off.

This angle wasn't immediately shown in the replays, but it shows the call was good. So, that takes care of the first incendiary issue--was it a bad (i.e., erroneous) call? The answer: no. After that, the question then becomes one of timing and consistency, of which there is a much stronger case for flame. It is a really fair point that this was a pretty reasonably officiated game up until this point. No real cases of "refball." This coming at such a critical point makes it feel incredibly unreasonable--it effectively sealed the deal for the Chiefs. But--does the fact that it's a critical time in the game now mean that penalties are now on the table? Had the Eagles defense looked even remotely functional--they generated zero sacks and even zero tackles for negative yardage--the game wouldn't have been close at all; would the call have still felt so critical? I don't know the answers to these questions definitively, and I was certainly disappointed myself with how the game ended despite not having a dog in this particular fight. 

Sunday, February 12, 2023

The Force Explosion Condition is Consistent with Spherically Symmetric CCSN Explosions


One of the major challenges in Core-collapse Supernova (CCSN) theory is to predict which stars explode and which collapse to black holes...The collapsing core bounces at the nuclear densities and launches the shock wave. If the blast wave overwhelms the collapsing star, the star explodes as a core-collapse supernova (CCSN) explosion (Li et al. 2011; Horiuchi et al. 2011).

we show that the FEC [(force explosion condition)] is consistent with the explosion condition when using actual neutrino transport in GR1D simulations...since most 1D simulations do not explode, to facilitate this test, we enhance the heating efficiency within the gain region.

With small, yet practical modifications, we show that the FEC predicts the explosion conditions in spherically symmetric CCSN simulations that use neutrino transport.

Discovery of an isolated dark dwarf galaxy in the nearby universe

arXiv (accepted for publication in ApJ):  

Based on a new H I survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H I cloud without any optical counterpart, named FAST J0139+4328...These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083.
Moreover, this disk galaxy has an extremely low absolute magnitude (M_B >-10.0 mag).

This is an insanely low absolute magnitude. For reference, a normal absolute magnitude for a galaxy like this might be around 10.

Furthermore, we obtained that the H I mass of this galaxy is (8.3±1.7)e7 SM, and the dynamical mass to total baryonic mass ratio is 47±27, implying that dark matter dominates over baryons in FAST J0139+4328. 

That's a substantial error bar--I wonder if future observations can constrain that much better.


And they got a hit: the radio waves emitted by a cloud of HI 94 million light-years away were consistent with a rotating disk galaxy, without the optical light expected of one. Follow-up observations in infrared and ultraviolet revealed a faint smattering of stars.

 "This is the first time that a gas-rich isolated dark galaxy has been detected in the nearby Universe," the researchers write.

There are a few other dark galaxy candidates, namely HI 1225+01 (ADS) and HI1232+20 (arXiv). 

Thermal vacuum testing for the Europa Clipper

NASA (via YouTube ): We'll be back soon. The spacecraft is currently undergoing vacuum testing. I was a huge fan of the livestream for b...