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Modern theory from ancient impacts

Around 4 billion years ago, the solar system was far less hospitable than we find it now. Many of the large bodies we know and love were present, but probably looked considerably different, especially the Earth. We know from a range of sources, including ancient meteorites and planetary geology, that around this time there were vastly more collisions between, and impacts from, asteroids originating in the Mars-Jupiter asteroid belt.

Knowledge of these events is especially important to us, as the time period in question is not only when the surface of our planet was taking on a more recognizable form, but was also when life was just getting started. With more accurate details of Earth’s rocky history, it could help researchers answer some long-standing questions concerning the mechanisms responsible for life, as well as provide information for other areas of life science.

“Meteorites provide us with the earliest history of ourselves,” said Professor Yuji Sano from the Atmosphere and Ocean Research Institute at the University of Tokyo. “This is what fascinated me about them. By studying properties, such as radioactive decay products, of meteorites that fell to Earth, we can deduce when they came and where they came from. For this study we examined meteorites that came from Vesta, the second-largest asteroid after the dwarf planet Ceres.”

Sano and his team found evidence that Vesta was hit by multiple impacting bodies around 4.4 billion to 4.15 billion years ago. This is earlier than 3.9 billion years ago, which is when the late heavy bombardment (LHB) is thought to have occurred. Current evidence for the LHB comes from lunar rocks collected during the Apollo moon missions of the 1970s, as well as other sources. But these new studies are improving upon previous models and will pave the way for an up-to-date database of early solar impact records.

“That Vesta-origin meteorites clearly show us impacts earlier than the LHB raises the question, ‘Did the late heavy bombardment truly occur?'” said Sano. “It seems to us that early solar system impacts peaked sooner than the LHB and reduced smoothly with time. It may not have been the cataclysmic period of chaos that current models describe.”

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ProgrammableWeb

10 Popular Accounting APIs

In recent years, the accounting software market has grown in value to over $12 Billion, with an expected value of over $19 billion by 2025. This growth is driven by digital transformation in the accounting industry, thanks to technology such as application integration, cloud computing, automation, artificial intelligence and decentralized ledgers (Blockchain).

Developers who want to cash in on the huge accounting software market need to find the correct APIs for their needs.

What is an Accounting API?

Accounting APIs are Application Programming Interfaces that enable developers to access, and create or integrate applications with, accounting software.

The best place to find these APIs is in the Accounting category of ProgrammableWeb. There, developers can search through scores of APIs and other tools for management accounting, bookkeeping, payroll, invoicing, taxes, forensic analysis, auditing, cost analysis, and more.

In this article, the 10 most popular Accounting APIs are highlighted. The APIs were chosen based on website traffic on ProgrammableWeb.

1. Xero Payroll API

Xero is an online accounting system designed for small businesses and their advisors. The Xero Payroll APITrack this API exposes the application’s payroll related functions. The RESTful API can be used for a variety of purposes including syncing employee details and importing timesheets.

2. Concur API

Concur from SAP provides online tools to manage travel and expense reporting and reimbursement. The Concur APITrack this API allows integration with applications of customer companies, partner service providers, or independent third-party developers including mobile app developers. API methods support submission and tracking of travel requests and booking of transportation and lodging, either for individuals or for groups completing the same travel. Methods also support creating, updating, and submitting expense reports as part of a reimbursement process.

3. Intuit QuickBooks Online Accounting API

The Intuit QuickBooks Online Accounting APITrack this API gives users access to QuickBooks Online accounting features and payment processing services. Using this API in an application enables users to connect to QuickBooks Online, sign in with their Intuit Account, and instantly access their QuickBooks Online company data. QuickBooks is an accounting software from Intuit that is primarily targeted to small and medium business accountants.

Intuit Quickbooks API is available for third-party developers. Screenshot: Intuit

4. Twinfield API

The Twinfield API integrates online accounting services into web services. With the API, developers can integrate transaction data including bank, cash, purchase, sales, and statements, as well as manage customers, suppliers, and transactions. It is available in XML format.

5. Zoho Books API

The Zoho Books API is accounting software for small businesses. It is RESTful, HTTP and JSON formatted, and allows access to all the typical Zoho Books functionalities, while also offering a platform for customization. Through Zoho Books, users can send invoices, accept payments, and manage and categorize cash flow.

6. Jasmin API

Jasmin Software is cloud Business Management software from a company called Primavera based in Portugal. The Jasmin APITrack this API exposes the functions of the Jasmin application and can be used for a variety of purposes such as creating transactions like invoices and credit notes, and getting business data.

7. Sage Accounting API

The Sage Accounting APITrack this API allows users to access accounting features to integrate into business applications. Manage ledgers, contacts, banking, status codes, currency, taxes, user accounts and other aspects of the Sage accounting and business management platform with the API.

8. FreshBooks API

FreshBooks is an all-in-one small business invoicing and accounting solution. The FreshBooks APITrack this API is an interface for accessing FreshBooks data using JSON. The API can be used to create web and desktop applications that integrate with an account. API methods are available to manage clients, invoices, expenses, estimates, reports, accounting and more.

Connect with small business accounting services via FreshBooks API

Connect with small business accounting services via FreshBooks API. Screenshot: FreshBooks

9. Veryfi API

Veryfi provides software to automate project bookkeeping. The Veryfi APITrack this API is an optical character recognition (OCR) API for real-time data extraction from receipts, bills & invoices. The API features ICR (intelligent character recognition) to capture receipts, extract data, categorize data such as vendors (from logos), taxes, currency and offer intelligent insights for business.

10. Receipt Bank API

Receipt Bank is a web based service that converts physical receipts and invoices into data. The data can be used however clients want and the scanned receipts are stored by Receipt Bank. The APITrack this API lets developers integrate the service into third party applications. These applications include Dropbox, FreeAgent, FreshBooks, KashFlow & Xero. For the API documentation, developers should contact the provider.

See the Accounting category for articles and other resources, including more than 190 APIs, SDKs, and Source Code Samples.

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ALMA resolves gas impacted by young jets from supermassive black hole

Astronomers obtained the first resolved image of disturbed gaseous clouds in a galaxy 11 billion light-years away by using the Atacama Large Millimeter/submillimeter Array (ALMA). The team found that the disruption is caused by young powerful jets ejected from a supermassive black hole residing at the center of the host galaxy. This result will cast light on the mystery of the evolutionary process of galaxies in the early Universe.

It is commonly known that black holes exert strong gravitational attraction on surrounding matter. However, it is less well known that some black holes have fast-moving streams of ionized matter, called jets. In some nearby galaxies, evolved jets blow off galactic gaseous clouds, resulting in suppressed star formation. Therefore, to understand the evolution of galaxies, it is crucial to observe the interaction between black hole jets and gaseous clouds throughout cosmic history. However, it had been difficult to obtain clear evidence of such interaction, especially in the early Universe.

In order to obtain such clear evidence, the team used ALMA to observe an interesting object known as MG J0414+0534. A distinctive feature of MG J0414+0534 is that the paths of light traveling from it to Earth are significantly distorted by the gravity of another ‘lensing’ galaxy between MG J0414+0534 and us, causing significant magnification.

“This distortion works as a ‘natural telescope’ to enable a detailed view of distant objects,” says Takeo Minezaki, an associate professor at the University of Tokyo.

Another feature is that MG J0414+0534 has a supermassive black hole with bipolar jets at the center of the host galaxy. The team was able to reconstruct the ‘true’ image of gaseous clouds as well as the jets in MG J0414+0534 by carefully accounting for the gravitational effects exerted by the intervening lensing galaxy.

“Combining this cosmic telescope and ALMA’s high-resolution observations, we obtained exceptionally sharp vision, that is 9,000 times better than human eyesight,” adds Kouichiro Nakanishi, a project associate professor at the National Astronomical Observatory of Japan/SOKENDAI. “With this extremely high resolution, we were able to obtain the distribution and motion of gaseous clouds around jets ejected from a supermassive black hole.”

Thanks to such a superior resolution, the team found that gaseous clouds along the jets have violent motion with speeds as high as 600 km/s, showing clear evidence of impacted gas. Moreover, it turned out that the size of the impacted gaseous clouds and the jets are much smaller than the typical size of a galaxy at this age.

“We are perhaps witnessing the very early phase of jet evolution in the galaxy,” says Satoki Matsushita, a research fellow at Academia Sinica Institute of Astronomy and Astrophysics. “It could be as early as several tens of thousands of years after the launch of the jets.”

“MG J0414+0534 is an excellent example because of the youth of the jets,” summarizes Kaiki Inoue, a professor at Kindai University, Japan, and the lead author of the research paper which appeared in the Astrophysical Journal Letters. “We found telltale evidence of significant interaction between jets and gaseous clouds even in the very early evolutionary phase of jets. I think that our discovery will pave the way for a better understanding of the evolutionary process of galaxies in the early Universe.”

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Novel techniques for mining patented gene therapies offer promising treatment options

The global gene therapy market is expected to reach $13 billion by 2024 as new treatment options target cancers and other diseases.

Now, a team of scientists from Purdue University and other research institutions around the world have come together to better understand the growing number of worldwide patented innovations available for gene therapy treatment. They specifically focus on nonviral methods, which use synthetic or natural compounds or physical forces to deliver materials generally less toxic than their viral counterparts into the therapy treatments.

“The possibility of using nonviral vectors for gene therapy represents one of the most interesting and intriguing fields of gene therapy research,” said Marxa Figueiredo, an associate professor of basic medical sciences in Purdue’s College of Veterinary Medicine, who helped lead the research team and works with the Purdue Research Foundation Office of Technology Commercialization to patent her technologies related to health. “This is an innovative method for identifying the technological routes used by universities and companies across the world and uncovering emerging trends for different gene therapy sectors.”

The scientists used big data, patent and clinical data mining to identify technological trends for the gene therapy field. The team’s work is presented in the Feb. 7 edition of Nature Biotechnology. They envision that their analysis will help guide future developments for gene therapy.

This work brought together investigators from across the globe in a joint effort to use new databases and methods to better understand the trends of the gene therapy field in respect to nonviral vectors. Dimas Covas, coordinator of the Center for Cell-based Therapy, affiliated with the University of São Paulo in Brazil, lent his extensive experience in cell therapy. Aglaia Athanassiadou, Virginia Picanço-Castro and Figueiredo contributed their extensive experience on nonviral vectors for gene therapy. Cristiano Pereira and Geciane Porto brought their expertise in economics and business administration to the analyses. Each contribution was fundamental to achieving a new way to identify technological trends in this field.

“This work brought together investigators from very diverse disciplines to create a different perspective of the gene therapy field,” Figueiredo said. “Our groups continue to work individually or in collaboration to generate and patent new vectors to help fill the needs of this re-emerging field of nonviral gene therapy.”

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When the milky way collided with dwarf galaxy gaia-enceladus

The dwarf galaxy Gaia-Enceladus collided with the Milky Way probably approximately 11.5 billion years ago. A team of researchers including scientists from the Max Planck Institute for Solar System Research in Germany for the first time used a single star affected by the collision as a clue for dating. Using observational data from ground-based observatories and space telescopes, the scientists led by the University of Birmingham were able to determine the age of the star and the role it played in the collision. The research group describes its results in today’s issue of Nature Astronomy.

On cosmic time scales, the colliding and merging of galaxies is not uncommon. Even if both galaxies involved are of very different sizes, such a collision leaves clear traces in the larger one. For example, the smaller galaxy introduces stars with a different chemical composition, the motion of many stars is altered, and myriads of new stars are formed.

The Milky Way has encountered several other galaxies in its 13.5 billion-year history. One of them is the dwarf galaxy Gaia-Enceladus. To understand how this event affected our galaxy and changed it permanently, it is important to reliably date the collision. To this end, the researchers led by Prof. Dr. Bill Chaplin of the University of Birmingham turned their attention to a single star: ? Indi is found in the constellation Indus; with an apparent brightness comparable to that of Uranus, it is visible even to the naked eye and can be easily studied in detail.

“The space telescope TESS collected data from ? Indi already in its first month of scientific operation,” says Dr. Saskia Hekker, head of the research group “Stellar Ages and Galactic Evolution (SAGE)” at MPS and co-author of the new study. The space telescope was launched in 2018 to perform a full-sky survey and characterize as many stars as possible. “The data from TESS allow us to determine the age of the star very accurately,” Hekker adds.

Moreover, ? Indi provided clues on the history of the collision with the dwarf galaxy Gaia-Enceladus. To reconstruct its role in the collision, the research group evaluated numerous data sets on ? Indi obtained with the help of the spectrographs HARPS (High Accuracy Radial velocity Planet Searcher) and FEROS (Fiber-fed Extended Range Optical Spectrograph) of the European Southern Observatory, the Galaxy Evolution Experiment of the Apache Point Observatory in New Mexico, and ESA’s Gaia Space Telescope. This allowed them to specify both the chemical composition of the star and its movement within the galaxy with great precision.

The cosmic detective work produced a clear picture: v Indi has been part of the halo, the outer region of the Milky Way, and the collision changed its trajectory. “Since the motion of v Indi was affected by the collision, it must have taken place when the star was already formed,” Chaplin explains the line of argument. The age of the star therefore puts a constraint on the time of the collision.

To determine the age of a star, researchers use its natural oscillations, which can be observed as brightness fluctuations. “Similar to the way seismic waves on Earth allow conclusions about the interior of our planet, stellar oscillations help us to reveal the internal structure and composition of the star and thus its age,” explains co-author Dr. Nathalie Themessl.

The calculations carried out by MPS researchers and other research groups showed that with a probability of 95 percent the galaxy merger must have occurred 13.2 billion years ago. With a probability of 68 percent, the collision took place approximately 11.5 billion years ago. “This chronological classification not only helps us to understand how the collision changed our galaxy,” says Hekker. “It also gives us a sense, of how collisions and mergers impacted other galaxies and influenced their evolution.”

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Planet WASP-12b is on a death spiral, say scientists

Earth is doomed — but not for 5 billion years. Our planet will be roasted as our sun expands and becomes a red giant, but the exoplanet WASP-12b, located 600 light-years away in the constellation Auriga, has less than a thousandth of that time left: a comparatively paltry 3 million years.

A Princeton-led team of astrophysicists has shown that WASP-12b is spiraling in toward its host star, heading toward certain destruction. Their paper appears in the Dec. 27, 2019, issue of the Astrophysical Journal Letters.

WASP-12b is known as a “hot Jupiter,” a giant gaseous planet like our neighbor planet Jupiter, but which is very close to its own star, orbiting its sun in just 26 hours. (By contrast, we take 365 days to orbit, and even Mercury, the innermost planet of our solar system, takes 88 days.)

“Ever since the discovery of the first ‘hot Jupiter’ in 1995 — a discovery that was recognized with this year’s Nobel Prize in Physics — we have wondered how long such planets can survive,” said Joshua Winn, a professor of astrophysical sciences at Princeton and one of the authors of the paper. “We were pretty sure they could not last forever. The strong gravitational interactions between the planet and the star should cause the planet to spiral inward and be destroyed, but nobody could predict how long this takes. It might be millions of years, it might be billions or trillions. Now that we have measured the rate, for at least one system — it’s millions of years — we have a new clue about the behavior of stars as fluid bodies.”

The problem is that as WASP-12b orbits its star, the two bodies exert gravitational pulls on each other, raising “tides” like the ocean tides raised by the moon on Earth.

Within the star, these tidal waves cause the star to become slightly distorted and to oscillate. Because of friction, these waves crash and the oscillations die down, a process that gradually converts the planet’s orbital energy into heat within the star.

The friction associated with the tides also exerts a gravitational torque on the planet, causing the planet to spiral inward. Measuring how quickly the planet’s orbit is shrinking reveals how quickly the star is dissipating the orbital energy, which provides astrophysicists clues about the interior of stars.

“If we can find more planets like WASP-12b whose orbits are decaying, we’ll be able to learn about the evolution and eventual fate of exoplanetary systems,” said first author Samuel Yee, a graduate student in astrophysical sciences. “Although this phenomenon has been predicted for close-in giant planets like WASP-12b in the past, this is the first time we have caught this process in action.”

One of the first people to make that prediction that was Frederic Rasio, the Joseph Cummings Professor of Physics and Astronomy at Northwestern University, who was not involved in Yee and Winn’s work. “We’ve all been waiting nearly 25 years for this effect to be detected observationally,” Rasio said. “The implications of the short timescale measured for orbital decay are also very important. In particular it means that there must be many more hot Jupiters that have already gone all the way. When they get to the Roche limit — the tidal disruption limit for an object on a circular orbit — their envelopes might get stripped, revealing a rocky core that looks just like a super-Earth (or maybe a mini-Neptune if they can retain a bit of their envelope).”

Rasio also edits Astrophysical Journal Letters, the journal in which the new paper appears. The researchers had originally submitted their paper to a less-prestigious sister journal also published by the American Astronomical Society, but Rasio redirected it to ApJ Letters because of the “especially great significance” of the research. “Part of my job is to ensure that all major new discoveries presented in manuscripts submitted to the AAS Journals are considered for publication in ApJ Letters,” he said. “In this case it was a no-brainer.”

WASP-12b was discovered in 2008 through the transit method, in which astronomers observe a small dip in a star’s brightness as the planet passes in front of it, each time it completes an orbit. Since its discovery, the interval between successive dips has shortened by 29 milliseconds per year — an observation that was first noted in 2017 by co-author Kishore Patra, then an undergraduate at the Massachusetts Institute of Technology.

That slight shortening could suggest that the planet’s orbit is shrinking, but there are other possible explanations: If WASP-12b’s orbit is more oval-shaped than circular, for example, the apparent changes in the orbital period could be caused by the changing orientation of the orbit.

The way to be sure if the orbit is actually shortening is to watch the planet disappear behind its star, known as occultation. If the orbit is just changing its direction, the actual orbital period doesn’t change, so if transits occur more quickly than expected, occultations should occur more slowly. But if the orbit is truly decaying, the timing of both transits and occultations should shift in the same direction.

Over the last two years, the researchers have collected more data, including new occultation observations made with the Spitzer Space Telescope.

“These new data strongly support the orbital decay scenario, allowing us to firmly say that the planet is indeed spiraling toward its star,” said Yee. “This confirms the long-standing theoretical predictions and indirect data suggesting that hot Jupiters should eventually be destroyed through this process.”

This discovery will help theorists understand the internal workings of stars and interpret other data relating to tidal interactions, said Winn. “It also tells us about the lifetimes of hot Jupiters, a clue that might help shed light on the formation of these strange and unexpected planets.”

“The orbit of WASP-12b is decaying,” by Samuel W. Yee, Joshua N. Winn, Heather A. Knutson, Kishore C. Patra, Shreyas Vissapragada, Michael M. Zhang, Matthew J. Holman, Avi Shporer and Jason T. Wright, appears in the Dec. 27, 2019, issue of the Astrophysical Journal. The research was supported by Princeton University, the Heising-Simons Foundation, NASA Solar Systems grant NNX14AD22G, the Pennsylvania State University, the Eberly College of Science and the Pennsylvania Space Grant Consortium. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community: “We are most fortunate to have the opportunity to conduct observations from this mountain.”

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Stardust from red giants

Around 4.5 billion years ago, an interstellar molecular cloud collapsed. At its centre, the Sun was formed; around that, a disc of gas and dust appeared, out of which the earth and the other planets would form. This thoroughly mixed interstellar material included exotic grains of dust: “Stardust that had formed around other suns,” explains Maria Schoenbaechler, a professor at the Institute of Geochemistry and Petrology at ETH Zurich. These dust grains only made up a small percentage of the entire dust mass and were distributed unevenly throughout the disc. “The stardust was like salt and pepper,” the geochemist says. As the planets formed, each one ended up with its own mix.

Thanks to extremely precise measurement techniques, researchers are nowadays able to detect the stardust that was present at the birth of our solar system. They examine specific chemical elements and measure the abundance of different isotopes — the different atomic flavours of a given element, which all share the same number of protons in their nuclei but vary in the number of neutrons. “The variable proportions of these isotopes act like a fingerprint,” Schönbächler says: “Stardust has really extreme, unique fingerprints — and because it was spread unevenly through the protoplanetary disc, each planet and each asteroid got its own fingerprint when it was formed.”

Studying palladium in meteorites

Over the past ten years, researchers studying rocks from the Earth and meteorites have been able to demonstrate these so-called isotopic anomalies for more and more elements. Schoenbaechler and her group have been looking at meteorites that were originally part of asteroid cores that were destroyed a long time ago, with a focus on the element palladium.

Other teams had already investigated neighbouring elements in the periodic table, such as molybdenum and ruthenium, so Schoenbaechler’s team could predict what their palladium results would show. But their laboratory measurements did not confirm the predictions. “The meteorites contained far smaller palladium anomalies than expected,” says Mattias Ek, postdoc at the University of Bristol who made the isotope measurements during his doctoral research at ETH.

Now the researchers have come up with a new model to explain these results, as they report in the journal Nature Astronomy. They argue that stardust consisted mainly of material that was produced in red giant stars. These are aging stars that expand because they have exhausted the fuel in their core. Our sun, too, will become a red giant four or five billion years from now.

In these stars heavy elements such as molybdenum and palladium were produced by what is known at the slow neutron capture process. “Palladium is slightly more volatile than the other elements measured. As a result, less of it condensed into dust around these stars, and therefore there is less palladium from stardust in the meteorites we studied” Ek says.

The ETH researchers also have a plausible explanation for another stardust puzzle: the higher abundance of material from red giants on Earth compared to Mars or Vesta or other asteroids further out in the solar system. This outer region saw an accumulation of material from supernova explosions.

“When the planets formed, temperatures closer to the Sun were very high,” Schoenbaechler explains. This caused unstable grains of dust, for instance those with an icy crust, to evaporate. The interstellar material contained more of this kind of dust that was destroyed close to the Sun, whereas stardust from red giants was less prone to destruction and hence concentrated there. It is conceivable that dust originating in supernova explosions also evaporates more easily, since it is somewhat smaller. “This allows us to explain why the Earth has the largest enrichment of stardust from red giant stars compared to other bodies in the solar system” Schoenbaechler says.

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Scientists inch closer than ever to signal from cosmic dawn

Around 12 billion years ago, the universe emerged from a great cosmic dark age as the first stars and galaxies lit up. With a new analysis of data collected by the Murchison Widefield Array (MWA) radio telescope, scientists are now closer than ever to detecting the ultra-faint signature of this turning point in cosmic history.

In a paper on the preprint site ArXiv and soon to be published in the Astrophysical Journal, researchers present the first analysis of data from a new configuration of the MWA designed specifically to look for the signal of neutral hydrogen, the gas that dominated the universe during the cosmic dark age. The analysis sets a new limit — the lowest limit yet — for the strength of the neutral hydrogen signal.

“We can say with confidence that if the neutral hydrogen signal was any stronger than the limit we set in the paper, then the telescope would have detected it,” said Jonathan Pober, an assistant professor of physics at Brown University and corresponding author on the new paper. “These findings can help us to further constrain the timing of when the cosmic dark ages ended and the first stars emerged.”

The research was led by Wenyang Li, who performed the work as a Ph.D. student at Brown. Li and Pober collaborated with an international group of researchers working with the MWA.

Despite its importance in cosmic history, little is known about the period when the first stars formed, which is known as the Epoch of Reionization (EoR). The first atoms that formed after the Big Bang were positively charged hydrogen ions — atoms whose electrons were stripped away by the energy of the infant universe. As the universe cooled and expanded, hydrogen atoms reunited with their electrons to form neutral hydrogen. And that’s just about all there was in the universe until about 12 billion years ago, when atoms started clumping together to form stars and galaxies. Light from those objects re-ionized the neutral hydrogen, causing it to largely disappear from interstellar space.

The goal of projects like the one happening at MWA is to locate the signal of neutral hydrogen from the dark ages and measure how it changed as the EoR unfolded. Doing so could reveal new and critical information about the first stars — the building blocks of the universe we see today. But catching any glimpse of that 12-billion-year-old signal is a difficult task that requires instruments with exquisite sensitivity.

When it began operating in 2013, the MWA was an array of 2,048 radio antennas arranged across the remote countryside of Western Australia. The antennas are bundled together into 128 “tiles,” whose signals are combined by a supercomputer called the Correlator. In 2016, the number of tiles was doubled to 256, and their configuration across the landscape was altered to improve their sensitivity to the neutral hydrogen signal. This new paper is the first analysis of data from the expanded array.

Neutral hydrogen emits radiation at a wavelength of 21 centimeters. As the universe has expanded over the past 12 billion years, the signal from the EoR is now stretched to about 2 meters, and that’s what MWA astronomers are looking for. The problem is there are myriad other sources that emit at the same wavelength — human-made sources like digital television as well as natural sources from within the Milky Way and from millions of other galaxies.

“All of these other sources are many orders of magnitude stronger than the signal we’re trying to detect,” Pober said. “Even an FM radio signal that’s reflected off an airplane that happens to be passing above the telescope is enough to contaminate the data.”

To home in on the signal, the researchers use a myriad of processing techniques to weed out those contaminants. At the same time, they account for the unique frequency responses of the telescope itself.

“If we look at different radio frequencies or wavelengths, the telescope behaves a little differently,” Pober said. “Correcting for the telescope response is absolutely critical for then doing the separation of astrophysical contaminants and the signal of interest.”

Those data analysis techniques combined with the expanded capacity of the telescope itself resulted in a new upper bound of the EoR signal strength. It’s the second consecutive best-limit-to-date analysis to be released by MWA and raises hope that the experiment will one day detect the elusive EoR signal.

“This analysis demonstrates that the phase two upgrade had a lot of its desired effects and that the new analysis techniques will improve future analyses,” Pober said. “The fact that MWA has now published back-to-back the two best limits on the signal gives momentum to the idea that this experiment and its approach has a lot of promise.”

The research was supported in part by the U.S. National Science Foundation (grant #1613040). The MWA receives support from the Australian government and acknowledges Wajarri Yamatji people as the traditional owners of the observatory site.

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Putting the ‘bang’ in the Big Bang

As the Big Bang theory goes, somewhere around 13.8 billion years ago the universe exploded into being, as an infinitely small, compact fireball of matter that cooled as it expanded, triggering reactions that cooked up the first stars and galaxies, and all the forms of matter that we see (and are) today.

Just before the Big Bang launched the universe onto its ever-expanding course, physicists believe, there was another, more explosive phase of the early universe at play: cosmic inflation, which lasted less than a trillionth of a second. During this period, matter — a cold, homogeneous goop — inflated exponentially quickly before processes of the Big Bang took over to more slowly expand and diversify the infant universe.

Recent observations have independently supported theories for both the Big Bang and cosmic inflation. But the two processes are so radically different from each other that scientists have struggled to conceive of how one followed the other.

Now physicists at MIT, Kenyon College, and elsewhere have simulated in detail an intermediary phase of the early universe that may have bridged cosmic inflation with the Big Bang. This phase, known as “reheating,” occurred at the end of cosmic inflation and involved processes that wrestled inflation’s cold, uniform matter into the ultrahot, complex soup that was in place at the start of the Big Bang.

“The postinflation reheating period sets up the conditions for the Big Bang, and in some sense puts the ‘bang’ in the Big Bang,” says David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. “It’s this bridge period where all hell breaks loose and matter behaves in anything but a simple way.”

Kaiser and his colleagues simulated in detail how multiple forms of matter would have interacted during this chaotic period at the end of inflation. Their simulations show that the extreme energy that drove inflation could have been redistributed just as quickly, within an even smaller fraction of a second, and in a way that produced conditions that would have been required for the start of the Big Bang.

The team found this extreme transformation would have been even faster and more efficient if quantum effects modified the way that matter responded to gravity at very high energies, deviating from the way Einstein’s theory of general relativity predicts matter and gravity should interact.

“This enables us to tell an unbroken story, from inflation to the postinflation period, to the Big Bang and beyond,” Kaiser says. “We can trace a continuous set of processes, all with known physics, to say this is one plausible way in which the universe came to look the way we see it today.”

The team’s results appear today in Physical Review Letters. Kaiser’s co-authors are lead author Rachel Nguyen, and John T. Giblin, both of Kenyon College, and former MIT graduate student Evangelos Sfakianakis and Jorinde van de Vis, both of Leiden University in the Netherlands.

“In sync with itself”

The theory of cosmic inflation, first proposed in the 1980s by MIT’s Alan Guth, the V.F. Weisskopf Professor of Physics, predicts that the universe began as an extremely small speck of matter, possibly about a hundred-billionth the size of a proton. This speck was filled with ultra-high-energy matter, so energetic that the pressures within generated a repulsive gravitational force — the driving force behind inflation. Like a spark to a fuse, this gravitational force exploded the infant universe outward, at an ever-faster rate, inflating it to nearly an octillion times its original size (that’s the number 1 followed by 26 zeroes), in less than a trillionth of a second.

Kaiser and his colleagues attempted to work out what the earliest phases of reheating — that bridge interval at the end of cosmic inflation and just before the Big Bang — might have looked like.

“The earliest phases of reheating should be marked by resonances. One form of high-energy matter dominates, and it’s shaking back and forth in sync with itself across large expanses of space, leading to explosive production of new particles,” Kaiser says. “That behavior won’t last forever, and once it starts transferring energy to a second form of matter, its own swings will get more choppy and uneven across space. We wanted to measure how long it would take for that resonant effect to break up, and for the produced particles to scatter off each other and come to some sort of thermal equilibrium, reminiscent of Big Bang conditions.”

The team’s computer simulations represent a large lattice onto which they mapped multiple forms of matter and tracked how their energy and distribution changed in space and over time as the scientists varied certain conditions. The simulation’s initial conditions were based on a particular inflationary model — a set of predictions for how the early universe’s distribution of matter may have behaved during cosmic inflation.

The scientists chose this particular model of inflation over others because its predictions closely match high-precision measurements of the cosmic microwave background — a remnant glow of radiation emitted just 380,000 years after the Big Bang, which is thought to contain traces of the inflationary period.

A universal tweak

The simulation tracked the behavior of two types of matter that may have been dominant during inflation, very similar to a type of particle, the Higgs boson, that was recently observed in other experiments.

Before running their simulations, the team added a slight “tweak” to the model’s description of gravity. While ordinary matter that we see today responds to gravity just as Einstein predicted in his theory of general relativity, matter at much higher energies, such as what’s thought to have existed during cosmic inflation, should behave slightly differently, interacting with gravity in ways that are modified by quantum mechanics, or interactions at the atomic scale.

In Einstein’s theory of general relativity, the strength of gravity is represented as a constant, with what physicists refer to as a minimal coupling, meaning that, no matter the energy of a particular particle, it will respond to gravitational effects with a strength set by a universal constant.

However, at the very high energies that are predicted in cosmic inflation, matter interacts with gravity in a slightly more complicated way. Quantum-mechanical effects predict that the strength of gravity can vary in space and time when interacting with ultra-high-energy matter — a phenomenon known as nonminimal coupling.

Kaiser and his colleagues incorporated a nonminimal coupling term to their inflationary model and observed how the distribution of matter and energy changed as they turned this quantum effect up or down.

In the end they found that the stronger the quantum-modified gravitational effect was in affecting matter, the faster the universe transitioned from the cold, homogeneous matter in inflation to the much hotter, diverse forms of matter that are characteristic of the Big Bang.

By tuning this quantum effect, they could make this crucial transition take place over 2 to 3 “e-folds,” referring to the amount of time it takes for the universe to (roughly) triple in size. In this case, they managed to simulate the reheating phase within the time it takes for the universe to triple in size two to three times. By comparison, inflation itself took place over about 60 e-folds.

“Reheating was an insane time, when everything went haywire,” Kaiser says. “We show that matter was interacting so strongly at that time that it could relax correspondingly quickly as well, beautifully setting the stage for the Big Bang. We didn’t know that to be the case, but that’s what’s emerging from these simulations, all with known physics. That’s what’s exciting for us.”

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NASA’s Curiosity Rover finds an ancient oasis on Mars

If you could travel back in time 3.5 billion years, what would Mars look like? The picture is evolving among scientists working with NASA’s Curiosity rover.

Imagine ponds dotting the floor of Gale Crater, the 100-mile-wide (150-kilometer-wide) ancient basin that Curiosity is exploring. Streams might have laced the crater’s walls, running toward its base. Watch history in fast forward, and you’d see these waterways overflow then dry up, a cycle that probably repeated itself numerous times over millions of years.

That is the landscape described by Curiosity scientists in a Nature Geoscience paper published today. The authors interpret rocks enriched in mineral salts discovered by the rover as evidence of shallow briny ponds that went through episodes of overflow and drying. The deposits serve as a watermark created by climate fluctuations as the Martian environment transitioned from a wetter one to the freezing desert it is today.

Scientists would like to understand how long this transition took and when exactly it occurred. This latest clue may be a sign of findings to come as Curiosity heads toward a region called the “sulfate-bearing unit,” which is expected to have formed in an even drier environment. It represents a stark difference from lower down the mountain, where Curiosity discovered evidence of persistent freshwater lakes.

Gale Crater is the ancient remnant of a massive impact. Sediment carried by water and wind eventually filled in the crater floor, layer by layer. After the sediment hardened, wind carved the layered rock into the towering Mount Sharp, which Curiosity is climbing today. Now exposed on the mountain’s slopes, each layer reveals a different era of Martian history and holds clues about the prevailing environment at the time.

“We went to Gale Crater because it preserves this unique record of a changing Mars,” said lead author William Rapin of Caltech. “Understanding when and how the planet’s climate started evolving is a piece of another puzzle: When and how long was Mars capable of supporting microbial life at the surface?”

He and his co-authors describe salts found across a 500-foot-tall (150-meter-tall) section of sedimentary rocks called “Sutton Island,” which Curiosity visited in 2017. Based on a series of mud cracks at a location named “Old Soaker,” the team already knew the area had intermittent drier periods. But the Sutton Island salts suggest the water also concentrated into brine.

Typically, when a lake dries up entirely, it leaves piles of pure salt crystals behind. But the Sutton Island salts are different: For one thing, they’re mineral salts, not table salt. They’re also mixed with sediment, suggesting they crystallized in a wet environment — possibly just beneath evaporating shallow ponds filled with briny water.

Given that Earth and Mars were similar in their early days, Rapin speculated that Sutton Island might have resembled saline lakes on South America’s Altiplano. Streams and rivers flowing from mountain ranges into this arid, high-altitude plateau lead to closed basins similar to Mars’ ancient Gale Crater. Lakes on the Altiplano are heavily influenced by climate in the same way as Gale.

“During drier periods, the Altiplano lakes become shallower, and some can dry out completely,” Rapin said. “The fact that they’re vegetation-free even makes them look a little like Mars.”

Signs of a Drying Mars

Sutton Island’s salt-enriched rocks are just one clue among several the rover team is using to piece together how the Martian climate changed. Looking across the entirety of Curiosity’s journey, which began in 2012, the science team sees a cycle of wet to dry across long timescales on Mars.

“As we climb Mount Sharp, we see an overall trend from a wet landscape to a drier one,” said Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in Pasadena, California. JPL leads the Mars Science Laboratory mission that Curiosity is a part of. “But that trend didn’t necessarily occur in a linear fashion. More likely, it was messy, including drier periods, like what we’re seeing at Sutton Island, followed by wetter periods, like what we’re seeing in the ‘clay-bearing unit’ that Curiosity is exploring today.”

Up until now, the rover has encountered lots of flat sediment layers that had been gently deposited at the bottom of a lake. Team member Chris Fedo, who specializes in the study of sedimentary layers at the University of Tennessee, noted that Curiosity is currently running across large rock structures that could have formed only in a higher-energy environment such as a windswept area or flowing streams.

Wind or flowing water piles sediment into layers that gradually incline. When they harden into rock, they become large structures similar to “Teal Ridge,” which Curiosity investigated this past summer.

“Finding inclined layers represents a major change, where the landscape isn’t completely underwater anymore,” said Fedo. “We may have left the era of deep lakes behind.”

Curiosity has already spied more inclined layers in the distant sulfate-bearing unit. The science team plans to drive there in the next couple years and investigate its many rock structures. If they formed in drier conditions that persisted for a long period, that might mean that the clay-bearing unit represents an in-between stage — a gateway to a different era in Gale Crater’s watery history.

“We can’t say whether we’re seeing wind or river deposits yet in the clay-bearing unit, but we’re comfortable saying is it’s definitely not the same thing as what came before or what lies ahead,” Fedo said.

For more about NASA’s Curiosity Mars rover mission, visit:

https://mars.nasa.gov/msl/

https://nasa.gov/msl

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