How The Coronavirus Attacks the Heart? (Medicine)

A RUB research team has found out which mechanisms the coronavirus uses to attack the heart – and how it can be stopped.

The Sars-Cov-2 coronavirus can cause severe organ damage in humans. Heart complications are also one of the consequences of a Covid 19 infection. The severe acute respiratory syndrome triggered by corona is usually associated with additional stress on the heart, especially in people with weak hearts or other pre-existing cardiac diseases. The virus also attacks the heart directly, causing myocarditis and heart failure. But how does the virus get into the heart? And how can it be stopped?

Nazha Hamdani is head of the research area for molecular and experimental cardiology at the University Hospital Bochum.© Roberto Schirdewahn

Doctor Dr. Nazha Hamdani, who heads the research area for molecular and experimental cardiology at the University Hospital Bochum. The researcher closely followed the virus’ journey into the heart and discovered a new mechanism of entry and damage: the virus docks onto the heart cells using so-called extracellular vesicles and exosomes, i.e. particles outside the cell, and infects them.

Our study shows for the first time that there is another mechanism that the virus uses to get through the bloodstream into the human heart.- Nazha Hamdani

In order to track down the new entry mechanism, the research team at the University Hospital analyzed the blood sera and heart tissue structures of patients suffering from Covid-19 and those who died from the disease using histochemical methods and microscopy.

Virus detected in heart cells

In a first step, Hamdani’s team provided evidence that the virus can actually and directly be detected in the cells of the heart muscle. “Our observations show that the virus exerts pressure on the heart muscle, attacks and weakens the force of contraction, ie the pumping function of the heart,” says Hamdani.

Hamdani and her team analyze the blood serum of patients suffering from Covid-19 using light and electron microscopy.© Roberto Schirdewahn

But how does the virus penetrate the heart in the first place? In previous studies on Sars-Cov-2, it was already possible to demonstrate that the novel virus attaches itself to a certain surface molecule of the human cell, the angiotensin-converting protein, via an enzyme, the so-called spike protein, which sits on the outside of the virus envelope. Enzyme 2 (ACE-2), binds. “The virus penetrates the cell interior via the ACE-2 receptor and then multiplies. This process has already been observed in the lungs, intestines, kidneys and liver ”, Hamdani summarizes the results of international research groups so far. Since ACE-2 can also be found on the cell surface of the heart, the Bochum doctor assumed that the virus would also attack the heart in this way.

To their astonishment, Hamdani and her team found the infected ACE-2 receptor only in the endothelium, the cell layer on the inner surface of the blood cells, and in extracellular particles, but not in the heart muscle cells. For the doctor it was clear: “The virus infection of human cells succeeds via ACE-2, but the virus seeks its way into the heart independently of it”. So there had to be other factors that enable the virus to enter the heart’s vascular cells. Hamdani and her team found what they were looking for in just four months.

Discovered a new mechanism

The key are what are known as extracellular vesicles. These lie outside the cells and are responsible for cell-to-cell communication. They are able to transport molecules, and thus also the messenger RNA of the virus, from infected cells to healthy cells. “Like a taxi that drives through the bloodstream and distributes the genetic information of the virus,” explains Hamdani.

The research team made the vesicles visible using a fluorescent dye, so-called double gold marking, and then observed them through a special light microscope, a confocal microscope, and an electron microscope. They were able to clearly identify the vesicles including the virus and components such as double-stranded RNA and spike protein in the blood and heart cells of severely infected patients. Follow-up experiments should show whether other organ cells are also attacked via this additional mechanism.

Alternative entry gate

In addition, the Bochum researchers were able to support the existing findings that the virus also uses the protein Neuropilin-1 (NRP-1) as a gateway into the cells. “Neuropilin lies on the outer wall of the epithelium, the top layer of cells in human skin, and thus makes it easier for the virus to penetrate. We measured an increased NPR-1 activity in the heart cells. This indicates that neuropilin-1 is an alternative receptor for Sars-Cov-2 entry alongside the ACE-2 receptor, ”Hamdani explains the important find. Neuropilin produces the messenger substance interleukin-6, which in turn regulates the inflammatory reaction of the organism and is essential for immune defense processes. If the production of interleukin-6 increases, this can lead to cell damage and cell death.

By using fluorescent dyes, the particles in the cells can be made visible and the path of the virus can be precisely followed.© Roberto Schirdewahn

Why the novel Sars-Cov-2 is so virulent?

Hamdani’s research shows that this means that several mechanisms are available for the coronavirus to spread in human organs. “The fact that the new virus is able to distribute itself independently of receptors via infected endothelial vesicles sets it apart from its predecessor Sars-Cov-1 and makes it a lot more virulent,” explains Hamdani. “The susceptibility to infection is also favored by an inflamed and oxidized cell environment, as often occurs in the elderly, people with high blood pressure, diabetics or those affected by obesity,” the doctor continues. Hamdani has been researching the pathophysiological causes of heart disease for years. What they all have in common: inflamed and oxidized vascular cells. Such a cell environment also increases the risk of Covid 19 patients

Breakthrough in Covid-19 therapy

Since the beginning of the corona pandemic, therapies have been sought that can contain the virus infection and prevent severe disease. The new mechanism that the Bochum research team has uncovered holds a promising therapeutic approach in store. It could be possible to load the extracellular vesicles with a medicinal cocktail of antibodies, anti-oxidants and anti-inflammatory agents that stop the virus from spreading, reduce inflammation levels and boost the immune system. “Our future cocktail drug would help people who have not yet been vaccinated but are already infected,” says Hamdani, explaining the therapeutic potential. It would also work against all virus variants. “The drug should prevent entry into the heart and other organs, regardless of the type of mutant,” says the researcher.

Featured image: A RUB doctor has discovered how the coronavirus penetrates the heart muscle cells. © Roberto Schirdewahn

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Provided by Ruhr Universitat Bochum

OPTICON-Radionet PILOT (ORP), the Largest Astronomy Network in Europe, is Born (Astronomy)

Two astronomy networks come together to form the largest collaborative terrestrial astronomy network in Europe

To date, Europe has had two major collaborative networks for ground-based astronomy, OPTICON and RadioNet, operating respectively in optical and radio. Now, these networks have come together to form the largest collaborative network for ground-based astronomy in Europe. The new network, called OPTICON-Radionet PILOT (ORP), aims to harmonise observing methods and tools and to provide access to a wider range of astronomical facilities. Calar Alto Observatory (CAHA) and the Institute of Astrophysics of Andalusia (IAA-CSIC) participate in the project, which will be coordinated by the French National Centre for Scientific Research (CNRS), together with the University of Cambridge and the Max-Planck Institute for Radio Astronomy.

As our knowledge of the universe advances, research groups need an increasingly sophisticated range of techniques to analyse and understand astronomical phenomena. Faced with this scenario, the European Union has decided to bring together the OPTICON and RadioNet networks, which have successfully served their respective communities for the past twenty years.

The project, with €15 million in funding from the European Union’s H2020 programme, will enable the European astronomical community to now benefit from a network of some twenty telescopes and telescope arrays. The new programme will facilitate the astronomical community’s access to these infrastructures, in addition to training new generations of astronomers.

According to the management team, “it is very exciting to have this opportunity to further develop European integration in astronomy, and develop new scientific opportunities for astronomy research across Europe and globally”.

The ORP will in particular foster the development of the booming field of what is known as multi-messenger astronomy, which makes use of a wide range of wavelengths as well as gravitational waves, cosmic rays and neutrinos.  Removing barriers between communities by harmonising observation protocols and analysis methods in the optical and radio domains will enable astronomers to work better together when observing and monitoring transient and variable astronomical events.

A total of thirty-seven institutions from fifteen European countries, as well as from Australia and South Africa, have already joined the ORP consortium. Among the participating centres are Calar Alto Observatory (CAHA), which will offer telescope time to the network, and the Institute of Astrophysics of Andalusia (IAA-CSIC), which is part of the ORP network executive committee. “This is an excellent opportunity to join scientific efforts to optimise the use of astronomical observatories all over Europe”, say Jesús Aceituno and Jorge Iglesias, Calar Alto Director and IAA-CSIC researcher, respectively.

More info: Web OPTICON-Radionet PILOT

Provided by IAA-CSIC

MAAT: New “Eyes” For The OSIRIS Instrument of the Gran Telescopio Canarias (GTC) (Instrumentation / Astronomy)

MAAT, a visiting GTC instrument in the preliminary design phase, will bring the technique known as integral field spectroscopy to the OSIRIS instrument

The OSIRIS instrument began operating from the first light of the Gran Telescopio Canarias (GTC), in 2009, and has shown exceptional efficiency over more than a decade. In 2023 the MAAT module (acronym for Mirror-slicer Array for Astronomical Transients), which is now in the preliminary design phase, will be installed within OSIRIS and will add integral field spectroscopy (IFS) to the excellent image quality provided by the GTC.

The IFS technique has been a revolution, since it allows obtaining spectra of a large, two-dimensional area of ​​the sky (hence this technique is referred to as three-dimensional spectroscopy). In addition to providing data cubes, which record spectral and spatial information, the IFS technique allows images to be obtained at any wavelength within the observed spectral range. OSIRIS+MAAT will be a unique installation in ten-meter telescopes around the world, and will make the Gran Telescopio Canarias maintain its leadership in international astronomical observation.

The core of MAAT is an optical micro-slicer imaging system that allows, when combined with the OSIRIS spectrograph, to create a 3D view of a portion of the sky. It creates an image data cube where each spatial pixel has a spectrum as a third dimension. Analysis of the entire data cube allows the study of different objects within the MAAT field of view at different wavelengths.

“MAAT’s high-level scientific requirements will address the needs of the GTC community for a wide range of science topics, spanning all of astronomy given its unique observing capabilities. MAAT will play a fundamental role in synergy with other facilities that operate in the Roque de los Muchachos Observatory”, points out Francisco Prada, scientist at the Institute of Astrophysics of Andalusia (IAA-CSIC) and principal investigator of the project.

“MAAT will allow the identification and characterization of kilonovas, the study of the matter inside them and the electromagnetic emission associated with collisions involving neutron stars and black holes that emit gravitational waves”, points out Ángeles Pérez García, professor at the University of Salamanca. “MAAT will be key to understanding the origin of the discrepancies observed in the chemical abundances of ionized nebulae, a fundamental problem in astrophysics since the mid-20th century”, says David Jones, a researcher at the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna. Both scientists are coordinators of the MAAT working groups.

“The capabilities of MAAT coupled to OSIRIS will reveal the origin and evolution of planetary mass objects located at great distances from their stars, and will contribute to the characterization of the new brown dwarfs that will be discovered with the Euclid space mission”, comments Eduardo Martín Guerrero de Escalante, CSIC research professor and institutional representative of the IAC in the project consortium.

MAAT began its preliminary design phase on November 1, 2020, and is scheduled for first light in spring 2023. The preliminary design phase will end on July 30, 2021, and includes a detailed study of different aspects of the instrument, including the scientific and technical specifications, the reasoning of outstanding scientific cases and a preliminary design of the mechanics and optics of the instrument. “It also addresses the development of data analysis software that will be distributed to the GTC community to guarantee the scientific exploitation of the data obtained with MAAT”, says Enrique Pérez, IAA-CSIC scientist who participates in the instrument.


The members of the MAAT Collaboration are the Institute of Astrophysics of Andalusia (IAA-CSIC), which heads the project, the Institute of Astrophysics of Canary Islands (IAC), the DARK (Niels Bohr Institute, University of Copenhagen), and the Oskar Center Klein Institute of Cosmoparticle Physics (Stockholm University), who have recently signed a Memorandum of Understanding (MoU) laying the foundations for the design, construction and operation of MAAT. Researchers associated with MAAT are affiliated with the Department of Fundamental Physics of the University of Salamanca (USAL), National Institute of Astronomy, Optics and Electronics (INAOE), Liverpool John Moores University (LJMU) and Australian Astronomical Optics – Macquarie University (AAO- MQ). The MAAT project has the technical support and help of the GTC Office in La Palma, AAO-MQ, and the companies Proactive R&D and OpticalDevelopment (Spain) and Winlight (France).

All images credit: IAA/CSIC

Reference: F. Prada et al. “White paper on MAAT @ GTC”.

Provided by IAA-CSIC

What Ignites The Helium Halos of Early Galaxies Remains A Mystery (Cosmology / Astronomy)

A study looks at the galaxy IZw18, an analogue of the first galaxies that appeared in the universe, for the origin of the radiation that produces a helium halo around it

About thirteen and a half billion years ago, the first galaxies were formed, made up almost entirely of hydrogen and helium, the primordial elements that emerged after the Big Bang. Populated by a type of stars that are now extinct, they are beyond our observation capacity, and “analogue” galaxies are now being used to determine their properties, among them the origin of extensive ionized helium haloes common in primitive galaxies. IZw18, a nearby galaxy used as an analog for decades, now shows that these halos remain, for the time being, inexplicable.

“The dwarf galaxy IZw18 is one of the most metal-poor galaxies (in astrophysics, elements heavier than hydrogen and helium) in the nearby universe, and one of the most similar to the first galaxies. So the study of it allows us to glimpse the conditions that existed in the primordial universe”, highlights Carolina Kehrig, a researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who is leading an investigation that analyzes the properties of IZw18.

In 2015, this researcher led the discovery, around the small galaxy IZw18, of a very extensive region of ionized helium, a frequent structure in very distant galaxies with little abundance of metals, and which added another coincidence between IZw18 and primitive galaxies.

Helium ionization requires the presence of objects that emit radiation strong enough to strip electrons from helium atoms. And it was calculated that conventional ionization sources, such as Wolf-Rayet stars -very massive stars with very strong stellar winds- or collisions generated by supernova remnants, did not provide the energy needed to generate IZw18’s ionized helium halo.

The current work studies the effects that X-rays show on the ionization of helium in this dwarf galaxy, dominated by a single source: an X-ray binary, or a system formed by a star similar to the Sun that revolves around a common center of mass with a compact object, be it a neutron star or a black hole.

Contours of the X-ray emission in the galaxy IZw18, produced by a single X-ray binary. The crosses in the left and centre images mark the maximum emission in ionised helium (in the right image in red), which does not coincide with the position of the binary system. © IAA/CSIC

“High-mass X-ray binaries are a source of high-energy radiation and have been proposed in the literature as a possible mechanism for ionization of helium in galaxies with massive star formation -says Kehrig (IAA-CSIC)-. We investigated for the first time the temporal variability of the IZw18 X-ray binary and found that its low level of X-ray emission, as well as its small variations in the last thirty years, are insufficient to generate the ionized helium halo of the galaxy”.

The extended morphology of the helium halo, as well as the distance between its maximum emission and the position of the X-ray binary, revealed for the first time in this study, reinforce the hypothesis that X-ray photons cannot be responsible for the formation of the ionized helium halo in IZw18.

In previous work, this research group proposed that extremely hot stars, such as low metallicity supermassive stars or massive stars with practically no metals, could hold the key to solving the problem of the excitation of helium in IZw18. These would be very hot stars analogous to first generation stars (known as Population III stars) and which, according to theoretical models, would be composed only of hydrogen and helium and could have hundreds of times the mass of the Sun.

“However, the existence of stars of this type has not yet been observationally confirmed in any galaxy. So, after ruling out conventional sources and X-ray sources, we still do not know what ionizes helium halos in galaxies”, concludes Carolina Kehrig (IAA-CSIC).

Reference: C. Kehrig et al. “On the contribution of the X-Ray source to the extended nebular HeII emission in IZw18”. The Astrophysical Journal Letters, Feb 2021.

Provided by IAA/CSIC

A Method to Study Distorted White Dwarf Stars is Developed (Planetary Science)

The IAA-CSIC is leading a study to determine the properties of stars that, either because of rapid rotation or because they are in a very compact double system subject to strong tidal forces, show a flattened shape

Most stars, due to their rotation and gaseous character, show some flattening at the poles. But some rotate so fast that they take on a distinctly elongated shape, something that also happens in very close binary stars due to mutual attraction. The study of these fast rotators constitutes a theoretical challenge, since they require specific methods to determine their properties. A researcher at the Institute of Astrophysics of Andalusia publishes a study that analyzes, for the first time in a systematic way, the distortions in white dwarf stars, which will allow their radii, masses or temperatures to be determined with greater precision.

White dwarfs are the remains of a star like the Sun that has expelled its outermost layers and retains a very compact nucleus. The densities of these objects can amount to two tons per cubic centimeter, and they can host a mass equivalent to that of the Sun in a volume similar to that of the Earth.

“More and more binary star systems made up of white dwarfs are being found where the stars are highly distorted either by rotational forces, tidal forces, or both. We know, for example, stars that orbit around the common center of mass every few minutes, and that present clearly flattened shapes”, points out Antonio Claret, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who has developed the study.

These binary systems of white dwarfs are an excellent laboratory to deepen our understanding of the evolution of double stars, as well as the physics of tides in astronomical environments or to study gravitational waves, the ripples in the structure of spacetime predicted by Einstein. However, modelling these systems accurately was until now an impossible task.

Different examples of stars flattened due to their high rotational velocity. © IAA

“These new calculations will make it possible to study these complex systems more rigorously. For example, they will make it possible to distinguish more clearly what the contribution of period shifts due to gravitational wave emission is. They also show that it is necessary to distinguish between hot and cold stars in order to use one model or another to determine their characteristics, including temperature,” says Claret (IAA-CSIC).

These binary systems of white dwarfs are an excellent laboratory to deepen our understanding of the evolution of double stars, as well as the physics of tides in astronomical environments or to study gravitational waves, the ripples in the structure of spacetime predicted by Einstein. However, modelling these systems accurately was until now an impossible task.

“These new calculations will make it possible to study these complex systems more rigorously. For example, they will make it possible to distinguish more clearly what the contribution of period shifts due to gravitational wave emission is. They also show that it is necessary to distinguish between hot and cold stars in order to use one model or another to determine their characteristics, including temperature,” says Claret (IAA-CSIC).


To determine the temperature of deformed stars, the von Zeipel theorem was traditionally used, which proposed that in hot flattened stars -with temperatures of more than 8000 degrees- the temperature is proportional to the local gravity. This introduced the concept of “gravity darkening”, which causes the temperature at the poles of a flattened star to be higher than at the equator (in the Sun this effect is barely noticeable due to its low rotation speed).

“The value that von Zeipel assigned to the gravity darkening has been much debated theoretically, and the application of a wrong gravity darkening exponent implies a faulty determination of the star’s thermodynamics, which in turn implies obtaining the wrong luminosity, mass and age values,” says Antonio Claret (IAA-CSIC).

Antonio Claret developed in 2011 a new formalism to know the gravity darkening from the interior to the atmosphere of stars, and an important conclusion was derived from it: the von Zeipel theorem is only applicable to the deepest regions of the star. Since astrophysicists observe the outermost layers, this new model was the correct alternative to determine the essential parameters of the star with precision.

This new work is a continuation of the previous one, applied to white dwarfs and introducing quantum mechanics calculations. “There are some novel results: for example, we have mathematically related the variation of the specific entropy to the temperature distribution on the surfaces of distorted white dwarfs, and we have also generalised von Zeipel’s theorem to the case of very hot white dwarfs. However, such a theorem is still not valid, as demonstrated in 2011, for cold white dwarfs”, concludes Claret.

Reference: Claret. A. “Rotationally and tidally distorted compact stars. A theoretical approach to the gravity-darkening exponents for white dwarfs”. Astronomy & Astrophysics, April 2021.

Provided by IAA/CSIC

Gravitational Waves: Where Will Research Go in the Next 20 Years? (Astronomy)

 review  dedicated to the near future of gravitational wave research has been published in the scientific journal Nature, a topic that has fascinated many in recent years. Among the authors of the roadmap also Marica Branchesi, teacher at GSSI, associated with INFN.

Gravitational waves are one of the areas of research that is giving great emotions and is marked by epochal discoveries, such as their first observation announced by the LIGO-Virgo collaborations in 2016, and the observation of the merger of two neutron stars revealed for the first time, both with gravitational waves from LIGO and VIRGO interferometers, and with electromagnetic radiation from telescopes on the ground and in space, in 2017.

The work focuses on the next twenty years discussing the most important projects for gravitational physics and astronomy in the opinion of the Gravitational Wave International Committee  (GWIC), an organization created in 1997 to facilitate international collaboration and cooperation in the construction and operation of the main infrastructures dedicated to the research of gravitational waves.

Link to the article:

According to Nature, the new observation window of gravitational astronomy will provide data that will transform our current knowledge in the fields of fundamental physics, astrophysics and cosmology.

 Thanks to the future generation of terrestrial observatories planned for 2030, the Einstein Telescope (in Europe) and the Cosmic Explorer (in the USA) and the LISA space mission it will be possible to observe mergers of black holes and neutron stars going back to the beginning of our Universe. Along with interferometric and electromagnetic detectors, Pulsar Timing Arrays (PTAs) telescopes will continue to evolve with new antenna networks, more sensitive and broadband receivers providing unique information on the dynamics of the largest galaxies in the Universe. 

In particular, among the leading projects for the near future: the LISA (Laser Interferometer Space Antenna) space detector, which is expected to be launched into orbit around the mid-1930s, and the European observatory Einstein Telescope (ET), which see an important involvement of Italy and the GSSI, also due to the recent appointment of Prof. Fernando Ferroni as project manager. 

 Gravitational-wave physics and astronomy in the 2020s and 2030s: Nature review presents the roadmap.

The near future of gravitational wave research has been published in the scientific journal Nature review. GWs have fascinated many in recent years with many discoveries and related research projects. Among the authors of this roadmap also Marica Branchesi, associate professor at GSSI, and INFN researcher. 

The 100 years since the publication of Albert Einstein’s theory of general relativity saw significant development of the understanding of the theory, the identification of potential astrophysical sources of sufficiently strong gravitational waves and development of key technologies for gravitational-wave detectors. In 2015, the first gravitational-wave signals were detected by the two US Advanced LIGO instruments. In 2017, Advanced LIGO and the European Advanced Virgo detectors pinpointed a binary neutron star coalescence that was also seen across the electromagnetic spectrum. The field of gravitational-wave astronomy is just starting, and this Roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitational-wave detectors,

In particular, among the leading projects for the GW research in the near future: the LISA space detector (Laser Interferometer Space Antenna) whose launch into orbit is foreseen in the middle years of 2030s, and the Einstein Telescope (ET), which see an important involvement of Italy and the GSSI, also due to the recent appointment of Prof. Fernando Ferroni in the scientific directorate of the project.

Link to the article:

Reference: Bailes, M., Berger, B.K., Brady, P.R. et al. Gravitational-wave physics and astronomy in the 2020s and 2030s. Nat Rev Phys (2021).

Provided by GSSI

Pulse Oximeters More Useful in COVID Screening for Older Adults (Medicine)

People have become accustomed to having their temperature checked during the pandemic because fever is a key indicator of COVID-19.

A new commentary by Washington State University College of Nursing Associate Professor Catherine Van Son and Clinical Assistant Professor Deborah Eti proposes that taking a temperature is a less useful indicator of infection in older adults and that a pulse oximeter be used instead.

The paper, published in Frontiers in Medicine, said baseline temperatures are lower in older adults. A lower baseline temperature means a fever may be overlooked using the CDC’s standard definition of 100.4 degrees Fahrenheit or greater.

“In fact,” the paper says, “upwards of 30% of older adults with serious infections show mild or no fever.”

Other common signs of COVID may also be dismissed and attributed to aging, such as fatigue, body aches and loss of taste or smell.

Additionally, some COVID-19 patients have no visible signs of having low oxygen levels, such as shortness of breath, yet have oxygen saturation below 90%. Such asymptomatic hypoxia can be associated with extremely poor outcomes.

Van Son and Eti say inexpensive, portable pulse oximeters should be considered for wide use in COVID-19 screenings of older adults because the devices can detect changes in oxygen saturation without other indications of infection.

“Detecting (asymptomatic hypoxia) is critical for the prevention of infection progression and initiating treatment,” they wrote. “Earlier interventions could help patients avoid highly invasive procedures (i.e., intubation) and improve the allocation of scarce healthcare resources.”

The creation of the commentary paper was supported by the Waldron O. & Janet S. Professorship in Geriatrics, focused on improving the lives of older adults. 

Reference: Catherine R. Van Son and Deborah U. Eti, “Screening for COVID-19 in Older Adults: Pulse Oximeter vs. Temperature”, Front. Med., 14 April 2021 |

Provided by Washington State University

The Hubble Constant From Catastrophic Collisions (Cosmology / Astronomy)

According to a new study from University College London, observing violent collisions of black holes and neutron stars could soon provide a new independent measure of the universe’s rate of expansion, helping to resolve the long-standing controversy over estimating the constant of Hubble. All the details on Physical Review Letters

Currently, the two best methods to estimate the expansion rate of the universe – the one using Cepheid variables and supernova explosions , and the measurement of the cosmic microwave background radiation – give very different values, suggesting that our theory describes the universe itself could be wrong. A third type of measurement, which exploits the potential of multi-message astronomy and which is based on the observation of electromagnetic emissions and gravitational waves generated by the merger of black holes and neutron stars, should help resolve the disagreement and clarify whether our theory of the universe actually needs to be rewritten.

A new study published in Physical Review Letters presents the results of a simulation of 25,000 merger scenarios between black holes and neutron stars , the aim of which was to understand how many of these mergers could potentially be detected by instruments on Earth. The researchers found that, by 2030, Earth instruments could perceive ripples in spacetime caused by up to 3,000 such mergers and that for about 100of these events the telescopes will also be able to pick up radiation emissions. Scientists concluded that these data would be sufficient to provide a completely independent new measure of the expansion rate of the universe, accurate and reliable enough to confirm or deny the need for new physics. The idea that the gravitational waves generated by these catastrophic events could put an end to the dispute over the expansion of the universe is not new: the same authors had proposed it a couple of years ago .

“A neutron star is a dead star, generated when a very large star explodes and then collapses,” explains Stephen Feeney of the Department of Physics and Astronomy at UCL ( University College London ), first author of the study. “It is incredibly dense – typically about 10 miles in diameter and up to twice the mass of the Sun. Its collision with a black hole is a catastrophic event, causing ripples in spacetime known as gravitational waves, which we can detect on the Earth with observers like Ligo and Virgo ».

Gravitational waves are detected by two observatories in the United States ( Ligo ), one in Italy ( Virgo ) and one in Japan ( Kagra ). A fifth observatory, Ligo-India , is currently under construction. “Advances in the sensitivity of equipment that detect gravitational waves,” continues Feeney, “together with the new detectors in India and Japan, will lead to a huge leap forward in terms of the number of events of this type that we will be able to detect.”

To calculate the expansion rate of the universe – the Hubble constant – astrophysicists need to know the distance of astronomical objects from Earth and the speed at which they are moving away. Gravitational wave analysis tells us how far away the collision is, leaving only the speed to be determined. To understand how fast the galaxy hosting a collision is moving away, we observe the redshift , or how the wavelength of the light produced by a source is increased due to its movement. The radiation emissions that may accompany these collisions help us pinpoint the galaxy where the collision occurred, allowing researchers to combine distance and redshift measurements.

“The computer models of these catastrophic events are incomplete and this study should provide additional motivation for improving them. If our assumptions are correct, many of these collisions will produce no detectable radiation emissions: the black hole will swallow the star without a trace. But in some cases a smaller black hole could destroy the neutron star before engulfing it, leaving matter outside the hole itself that emits electromagnetic radiation, ”Feeney says.

Currently, the two best estimates of the universe’s rate of expansion are 67 kilometers per second per megaparsec and 74kilometers per second per megaparsec. The first derives from the analysis of the cosmic microwave background while the second comes from the comparison of stars at different distances from the Earth, in particular the Cepheid variables and type Ia supernovae. “Since the microwave background measurement requires a complete theory of the universe, as opposed to the stellar method, the disagreement offers tantalizing evidence of a new physics, which is beyond our current understanding. However, before we can make such claims we need confirmation of disagreement by completely independent observations. We believe these may be provided by black hole-neutron star collisions, ”Feeney confidently concludes.

Featured image: Observing violent collisions of black holes and neutron stars could soon provide a new measure of the universe’s rate of expansion, helping to resolve a long-standing controversy, according to a new UCL study, published in Physical Review Letters. Credits: University College London

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Provided by INAF

Review Outlines Approaches To Deliver Radiation To Tumors While Sparing Healthy Tissue (Medicine)

A comprehensive review by University of North Carolina researchers and colleagues highlights the optimal ways that focused, high-dose radiation can be delivered to various types of tumors while sparing normal tissue and mitigating long-term side effects. The review was reported as a special issue in the International Journal of Radiation Oncology, Biology, Physics on May 1, 2021.

This analysis was based on an exhaustive review of data and the literature published largely in the past decade. It updates an earlier review that primarily focused on the effects of conventional radiation therapy on normal tissue. This new review also includes important analyses of how well high-dose radiation can destroy small tumors, such as small brain lesions, lung lesions, and cancers that metastasize to other parts of the body.

“We undertook this review because we have an ever-increasing knowledge about the dose and volume of tissue to which we can direct radiation to both eradicate tumors while also safeguarding the surrounding normal tissue,” said Lawrence B. Marks, MD, chair of the UNC Department of Radiation Oncology and Dr. Sidney K. Simon Distinguished Professor of Oncology Research at UNC Lineberger Comprehensive Cancer Center. “Today, we are better able to tailor radiotherapy to optimize benefit and minimize risk.”

Conventional radiotherapy, developed nearly a century ago, often broadly hits the tumor and some healthy tissue surrounding the tumor, and is administered in low daily doses, usually over many weeks. For some patients, their cancer can be treated with more advanced techniques, called stereotactic body radiation therapy, or radiosurgery, that target smaller areas of tissue that are primarily cancerous, treating them at a high dose per day and usually administered for one to five days. These radiosurgery treatments are the focus of this recently published report.

Marks said UNC is a leader in radiosurgery treatments. “We are lucky to have specialized equipment and expertise to deliver these types of treatments.” He added that UNC’s multidisciplinary approach to cancer care brings together clinical collaborators to work in partnership with radiosurgery program to care for a wide range of cancers, including brain, thoracic, gastrointestinal and genitourinary cancers.

“New computational methods and machines allow us to deliver radiotherapy much more accurately today, allowing us to limit the area where the radiation is targeted, thereby giving us the ability to increase the dose per day,” Marks said. “However, at this point in time we can only use this approach for smallish-sized tumors, but newer techniques may allow us to extend this approach to larger tumors as well.”

Because it takes years for data to accrue and mature, the next review will be done when there are discernable shifts or changes in treatment practice patterns, according to the authors. However, there is a large review due out next year, in which Marks is participating, that is focusing on use of radiotherapy in pediatric cancers. Radiotherapy is often used sparingly in children due to later-in-life side effects, therefore making it important to know when best to use these treatments.

“Radiation therapy is now safer than ever. Our analysis will help support the growing use of the latest forms of radiotherapy, which are proving to be a very effective in treating many primary and metastatic lesions,” Marks concluded.

In addition to Marks, the other authors from UNC include Shiva Das, PhD, Nathan Sheets, MD, Panayiotis Mavroidis, PhD, DABR, and Trevor Royce, MD, MPH. Other members of Marks’ steering committee include Jimm Grimm, PhD, Geisinger Cancer Institute, Danville, PA, and Thomas Jefferson University, Philadelphia; Andrew Jackson, PhD, and Ellen Yorke, PhD, Memorial Sloan-Kettering Cancer Center, New York; Brian D. Kavanagh, MD, University of Colorado School of Medicine, Aurora, CO; and Jinyu Xue, PhD, NYU Langone Medical Center, New York.

Featured image: UNC Lineberger Comprehensive Cancer Center’s Lawrence Marks, MD, and colleagues have published a comprehensive review that highlights the optimal ways that focused, high-dose radiation can be delivered to various types of tumors while sparing normal tissue and mitigating long-term side effects. © UNC Health

Reference: Jimm Grimm, Lawrence B. Marks et al., “High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic (HyTEC): An Overview”, VOLUME 110, ISSUE 1, pp. 1-10, 2021. DOI:

Provided by UNC Lineberger Comprehensive Cancer Center