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Revelada la distribución de la materia oscura alrededor de las galaxias hace 12 mil millones de años



El residuo de radiación del Big Bang, distorsionado por la materia oscura hace 12 mil millones de años. Crédito: Reiko Matsushita

Los científicos han estudiado la naturaleza de la materia oscura que rodea a las galaxias tal como eran hace 12 000 millones de años, miles de millones de años más atrás que nunca. Sus hallazgos ofrecen la tentadora posibilidad de que las reglas fundamentales de la cosmología puedan diferir al examinar la historia antigua de nuestro universo. La colaboración fue dirigida por científicos de[{» attribute=»»>Nagoya University in Japan and the findings were published today (August 1) in the journal Physical Review Letters.

Seeing something that happened such a long time ago is challenging. Because of the speed of light is finite, we see distant galaxies not as they are today, but as they were billions of years ago. But even more difficult is observing dark matter, which does not emit light.

“It was a crazy idea. No one realized we could do this.” — Professor Masami Ouchi

Consider a distant source galaxy, even farther away than the target galaxy whose dark matter one wants to investigate. As predicted by Einstein’s theory of general relativity, the gravitational attraction of the foreground galaxy, including its dark matter, distorts the surrounding space and time. As the light from the source galaxy travels through this distortion in spacetime, it bends, changing the apparent shape of the galaxy. The greater the amount of dark matter, the greater the resulting distortion. Therefore, astronomers can measure the amount of dark matter around the foreground galaxy (the “lens” galaxy) from the distortion.

However, beyond a certain threshold, scientists encounter a problem. In the deepest reaches of the universe, the galaxies are incredibly faint. As a result, the farther away from Earth we look, the less effective the gravitational lensing technique becomes. Because the lensing distortion is subtle and difficult to detect in most cases, many background galaxies are needed to detect the signal.

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Most previous studies have remained stuck at the same limits. Unable to detect enough distant source galaxies to measure the distortion, they could only analyze dark matter from no more than 8-10 billion years ago. These limitations left open the question of the distribution of dark matter between this time and 13.7 billion years ago, around the beginning of our universe.

To overcome these challenges and observe dark matter from the farthest reaches of the universe, a team of researchers led by Hironao Miyatake from Nagoya University, in collaboration with the University of Tokyo, the National Astronomical Observatory of Japan, and Princeton University, used a different source of background light, the microwaves released from the Big Bang itself.

First, using data from the observations of the Subaru Hyper Suprime-Cam Survey (HSC), the team identified 1.5 million lens galaxies using visible light, selected to be seen 12 billion years ago.

Next, to overcome the lack of galaxy light even farther away, they employed microwaves from the cosmic microwave background (CMB), the radiation residue from the Big Bang. Using microwaves observed by the European Space Agency’s Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.

“Look at dark matter around distant galaxies?” asked Professor Masami Ouchi of the University of Tokyo, who made many of the observations. “It was a crazy idea. No one realized we could do this. But after I gave a talk about a large distant galaxy sample, Hironao came to me and said it may be possible to look at dark matter around these galaxies with the CMB.”

“Most researchers use source galaxies to measure dark matter distribution from the present to eight billion years ago,” added Assistant Professor Yuichi Harikane of the Institute for Cosmic Ray Research, University of Tokyo. “However, we could look further back into the past because we used the more distant CMB to measure dark matter. For the first time, we were measuring dark matter from almost the earliest moments of the universe.”

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After a preliminary analysis, the scientists soon realized that they had a large enough sample to detect the distribution of dark matter. Combining the large distant galaxy sample and the lensing distortions in CMB, they detected dark matter even further back in time, from 12 billion years ago. This is only 1.7 billion years after the beginning of the universe, and thus these galaxies are seen soon after they first formed.

“I was happy that we opened a new window into that era,” Miyatake said. “12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well.” Galaxy clusters comprise 100-1000 galaxies bound by gravity with large amounts of dark matter.

“This result gives a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies, and how this picture evolves with time,” said Neta Bahcall, Eugene Higgins Professor of Astronomy, professor of astrophysical sciences, and director of undergraduate studies at Princeton University.

One of the most exciting discoveries from the study was related to the clumpiness of dark matter. According to the standard theory of cosmology, the Lambda-CDM model, subtle fluctuations in the CMB form pools of densely packed matter by attracting surrounding matter through gravity. This creates inhomogeneous clumps that form stars and galaxies in these dense regions. The group’s findings suggest that their clumpiness measurement was lower than predicted by the Lambda-CDM model.

Miyatake is enthusiastic about the possibilities. “Our finding is still uncertain,” he said. “But if it is true, it would suggest that the entire model is flawed as you go further back in time. This is exciting because if the result holds after the uncertainties are reduced, it could suggest an improvement of the model that may provide insight into the nature of dark matter itself.”

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“At this point, we will try to get better data to see if the Lambda-CDM model is actually able to explain the observations that we have in the universe,” said Andrés Plazas Malagón, associate research scholar at Princeton University. “And the consequence may be that we need to revisit the assumptions that went into this model.”

“One of the strengths of looking at the universe using large-scale surveys, such as the ones used in this research, is that you can study everything that you see in the resulting images, from nearby asteroids in our solar system to the most distant galaxies from the early universe. You can use the same data to explore a lot of new questions,” said Michael Strauss, professor and chair of the Department of Astrophysical Sciences at Princeton University.

This study used data available from existing telescopes, including Planck and Subaru. The group has only reviewed a third of the Subaru Hyper Suprime-Cam Survey data. The next step will be to analyze the entire data set, which should allow for a more precise measurement of the dark matter distribution. In the future, the research team expects to use an advanced data set like the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) to explore more of the earliest parts of space. “LSST will allow us to observe half the sky,” Harikane said. “I don’t see any reason we couldn’t see the dark matter distribution 13 billion years ago next.”

Reference: “First Identification of a CMB Lensing Signal Produced by 1.5 Million Galaxies at z~4: Constraints on Matter Density Fluctuations at High Redshift” by Hironao Miyatake, Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Nanaka Yamamoto, Atsushi J. Nishizawa, Neta Bahcall, Satoshi Miyazaki and Andrés A. Plazas Malagón, 1 August 2022, Physical Review Letters.
DOI: 10.1103/PhysRevLett.129.061301

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El MIT encuentra un «punto óptimo» de humedad interior para reducir la propagación de COVID-19



Un estudio del MIT muestra que mantener la humedad interior en una ubicación ideal puede reducir la propagación de COVID-19.

Una nueva investigación vincula los ambientes interiores muy secos y muy húmedos con lo peor[{» attribute=»»>COVID-19 outcomes.

We know proper indoor ventilation is key to reducing the spread of COVID-19. Now, a study by MIT researchers finds that indoor relative humidity may also influence the transmission of the virus.

Relative humidity is the amount of moisture in the air compared to the total moisture the air can hold at a given temperature before saturating and forming condensation.

In a study published in the Journal of the Royal Society Interface on November 16, the MIT team reports that maintaining an indoor relative humidity between 40 and 60 percent is associated with relatively lower rates of COVID-19 infections and deaths, while indoor conditions outside this range are associated with worse COVID-19 outcomes. To put this into perspective, most people are comfortable between 30 and 50 percent relative humidity, and an airplane cabin is at around 20 percent relative humidity.

The findings are based on the team’s analysis of COVID-19 data combined with meteorological measurements from 121 countries, from January 2020 through August 2020. Their study suggests a strong connection between regional outbreaks and indoor relative humidity.

In general, the researchers found that whenever a region experienced a rise in COVID-19 cases and deaths prevaccination, the estimated indoor relative humidity in that region, on average, was either lower than 40 percent or higher than 60 percent regardless of season. Nearly all regions in the study experienced fewer COVID-19 cases and deaths during periods when estimated indoor relative humidity was within a “sweet spot” between 40 and 60 percent.

“There’s potentially a protective effect of this intermediate indoor relative humidity,” suggests lead author Connor Verheyen, a PhD student in medical engineering and medical physics in the Harvard-MIT Program in Health Sciences and Technology.

“Indoor ventilation is still critical,” says co-author Lydia Bourouiba, director of the MIT Fluid Dynamics of Disease Transmission Laboratory and associate professor in the departments of Civil and Environmental Engineering and Mechanical Engineering, and at the Institute for Medical Engineering and Science at MIT. “However, we find that maintaining an indoor relative humidity in that sweet spot — of 40 to 60 percent — is associated with reduced COVID-19 cases and deaths.”

Seasonal swing?

Since the start of the COVID-19 pandemic, scientists have considered the possibility that the virus’ virulence swings with the seasons. Infections and associated deaths appear to rise in winter and ebb in summer. But studies looking to link the virus’ patterns to seasonal outdoor conditions have yielded mixed results.

Verheyen and Bourouiba examined whether COVID-19 is influenced instead by indoor — rather than outdoor — conditions, and, specifically, relative humidity. After all, they note that most societies spend more than 90 percent of their time indoors, where the majority of viral transmission has been shown to occur. What’s more, indoor conditions can be quite different from outdoor conditions as a result of climate control systems, such as heaters that significantly dry out indoor air.

Could indoor relative humidity have affected the spread and severity of COVID-19 around the world? And could it help explain the differences in health outcomes from region to region?

Tracking humidity

For answers, the team focused on the early period of the pandemic when vaccines were not yet available, reasoning that vaccinated populations would obscure the influence of any other factor such as indoor humidity. They gathered global COVID-19 data, including case counts and reported deaths, from January 2020 to August 2020,  and identified countries with at least 50 deaths, indicating at least one outbreak had occurred in those countries.

In all, they focused on 121 countries where COVID-19 outbreaks occurred. For each country, they also tracked the local COVID-19 related policies, such as isolation, quarantine, and testing measures, and their statistical association with COVID-19 outcomes.

For each day that COVID-19 data was available, they used meteorological data to calculate a country’s outdoor relative humidity. They then estimated the average indoor relative humidity, based on outdoor relative humidity and guidelines on temperature ranges for human comfort. For instance, guidelines report that humans are comfortable between 66 to 77 degrees Fahrenheit indoors. They also assumed that on average, most populations have the means to heat indoor spaces to comfortable temperatures. Finally, they also collected experimental data, which they used to validate their estimation approach.

For every instance when outdoor temperatures were below the typical human comfort range, they assumed indoor spaces were heated to reach that comfort range. Based on the added heating, they calculated the associated drop in indoor relative humidity.

In warmer times, both outdoor and indoor relative humidity for each country was about the same, but they quickly diverged in colder times. While outdoor humidity remained around 50 percent throughout the year, indoor relative humidity for countries in the Northern and Southern Hemispheres dropped below 40 percent in their respective colder periods, when COVID-19 cases and deaths also spiked in these regions.

For countries in the tropics, relative humidity was about the same indoors and outdoors throughout the year, with a gradual rise indoors during the region’s summer season, when high outdoor humidity likely raised the indoor relative humidity over 60 percent. They found this rise mirrored the gradual increase in COVID-19 deaths in the tropics.

“We saw more reported COVID-19 deaths on the low and high end of indoor relative humidity, and less in this sweet spot of 40 to 60 percent,” Verheyen says. “This intermediate relative humidity window is associated with a better outcome, meaning fewer deaths and a deceleration of the pandemic.”

“We were very skeptical initially, especially as the COVID-19 data can be noisy and inconsistent,” Bourouiba says. “We thus were very thorough trying to poke holes in our own analysis, using a range of approaches to test the limits and robustness of the findings, including taking into account factors such as government intervention. Despite all our best efforts, we found that even when considering countries with very strong versus very weak COVID-19 mitigation policies, or wildly different outdoor conditions, indoor — rather than outdoor — relative humidity maintains an underlying strong and robust link with COVID-19 outcomes.”

It’s still unclear how indoor relative humidity affects COVID-19 outcomes. The team’s follow-up studies suggest that pathogens may survive longer in respiratory droplets in both very dry and very humid conditions.

“Our ongoing work shows that there are emerging hints of mechanistic links between these factors,” Bourouiba says. “For now, however, we can say that indoor relative humidity emerges in a robust manner as another mitigation lever that organizations and individuals can monitor, adjust, and maintain in the optimal 40 to 60 percent range, in addition to proper ventilation.”

Reference: “Associations between indoor relative humidity and global COVID-19 outcomes” by C. A. Verheyen and L. Bourouiba, 16 November 2022, Journal of The Royal Society Interface.
DOI: 10.1098/rsif.2021.0865

This research was made possible, in part, by an MIT Alumni Class fund, the Richard and Susan Smith Family Foundation, the National Institutes of Health, and the National Science Foundation.

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Se completó la transferencia del canal de alimentación de la estación, sin impacto en las operaciones – Estación espacial



La Estación Espacial Internacional se muestra desde SpaceX Crew Dragon Endeavour durante un sobrevuelo del laboratorio en órbita que tuvo lugar el 8 de noviembre de 2021.

El 23 de noviembre, el equipo de Mission Control Houston modificó la ruta del suministro de energía para eliminar el uso de uno de los ocho canales de energía de la Estación Espacial Internacional. Este procedimiento se realizó en respuesta a lecturas inesperadas y disparos intermitentes del canal de alimentación 1B durante la noche. Cuando el canal de energía se disparó, las baterías ya no estaban cargadas a los niveles esperados, por lo que los operadores de vuelo cambiaron el equipo alimentado por 1B de 1B a 1A. Los sistemas de la estación espacial están en una configuración estable y el equipo está evaluando el evento y discutiendo planes futuros. Las próximas operaciones de la estación espacial, incluido el lanzamiento del sábado de la NASA y la misión de reabastecimiento comercial número 26 de SpaceX, así como las caminatas espaciales, no se verán afectadas.

Conozca más sobre las actividades del resort siguiendo las Blog de la estación espacial, @estación Espacial y @ISS_Investigación en Twitter, así como el Facebook de la EEI y Instagram de la EEI cuentas

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El Telescopio Webb hace un descubrimiento sin precedentes de exoplanetas en el espacio profundo



los poderoso telescopio webb no necesita tomar fotografías bonitas para revolucionar nuestra comprensión del cosmos.

Los astrónomos enfocaron el observatorio espacial, que logró llega a su puesto de avanzada a un millón de millas de la Tierra este año, en el exoplaneta similar a Saturno (significado planeta más allá de nuestro sistema solar) WASP-39 b. Es un gigante de gas caliente que orbita cerca de una estrella a 700 años luz de distancia. Previamente, los científicos utilizaron instrumentos especializados a bordo del Webb para detectar dióxido de carbono en este mundo extremo.

Ahora, por primera vez, han descubierto «un menú completo» de átomos y moléculas en las nubes de un exoplaneta, y algunos de ellos están interactuando. Esta última detección prueba que los astrónomos pueden observar las atmósferas de extraños exoplanetas y descifrar lo que sucede o se hace químicamente, y si estos mundos pudieran contener condiciones que podrían potencialmente albergar vida. (En nuestro planeta, la química atmosférica, responsable de crear atmósferas aislantes y capa protectora de ozonoes vital para la vida.)

La luz de una estrella a menudo puede impulsar reacciones químicas en un planeta, un proceso llamado «fotoquímica». Esto es lo que sucede en WASP-39 b.

«Los planetas están esculpidos y orbitados en el baño de radiación de la estrella anfitriona», dijo Natalie Batalha, astrónoma de la Universidad de California, Santa Cruz, que contribuyó a la nueva investigación. dijo en un comunicado de prensa. «En la Tierra, estas transformaciones permiten que la vida prospere». (Los cinco artículos de investigación que muestran el descubrimiento son listado en este comunicado de prensa de UC Santa Cruz.)

En concreto, el Telescopio Webb descubrió la presencia de vapor de agua, dióxido de azufre, monóxido de carbono, sodio y potasio, entre otros elementos. Para detectar tales moléculas en planetas distantes, los astrónomos dirigen el observatorio a exoplanetas conocidos en nuestro Via Láctea. Entonces como Mashable explicado anteriormenteestán haciendo algo muy profundamente inteligente:

Esperarán a que los planetas viajen más allá de sus estrellas brillantes. Esta luz estelar pasa a través de la atmósfera del exoplaneta, luego a través del espacio y finalmente hacia instrumentos llamados espectrógrafos a bordo de Webb (una estrategia llamada «espectroscopia de tránsito»). Son esencialmente prismas de alta tecnología, que separan la luz en un arcoíris de colores. Esto es lo más importante: ciertas moléculas, como el agua, en la atmósfera absorben tipos o colores específicos de luz. “Cada molécula tiene una dieta específica”, explicó Néstor Espinoza, investigador de exoplanetas en el Instituto de Ciencias del Telescopio Espacial, quien lidera el Telescopio espacial James Webb.

Entonces, si este color no aparece en el espectro de colores observado por un espectrógrafo Webb, significa que ha sido absorbido (o «consumido» por) la atmósfera del exoplaneta. En otras palabras, este elemento está presente en el cielo de este planeta. El espectrógrafo produce líneas (que designan diferentes tipos de luz), no imágenes bonitas; pero es una riqueza de información invaluable.

La detección particularmente atractiva en WASP-39b es el dióxido de azufre, que se produce cuando la luz de una estrella golpea la atmósfera de un planeta. Usando computadoras, los investigadores simularon las condiciones en esta atmósfera distante y determinaron que la fotoquímica formó esta molécula en las nubes espesas y esponjosas de WASP-39b.

Un gráfico que muestra las reacciones químicas en la atmósfera de WASP-39b.
Crédito: NASA/JPL-Caltech/Robert Hurt; Centro de Astrofísica-Harvard & Smithsonian / Melissa Weiss

«En la Tierra, estas transformaciones permiten que la vida prospere».

Ahora los astrónomos saben que pueden usar Webb para buscar atmósferas dinámicas en otros mundos distantes en espacio.

«Podremos obtener una imagen general de las atmósferas de los exoplanetas», dijo en un comunicado Laura Flagg, investigadora de exoplanetas en la Universidad de Cornell que trabajó en la investigación. «Es increíblemente emocionante saber que todo se va a reescribir. Es una de las mejores partes de ser científico».

Quieren más la ciencia y nuevas técnicas enviadas directamente a su bandeja de entrada? Regístrese para Boletín de las mejores historias de Mashable Este Dia.

moléculas en la atmósfera de un exoplaneta

Ilustración artística de moléculas que reaccionan a la luz solar en las nubes de un exoplaneta.
Crédito: Melissa Weiss / Centro de Astrofísica | Harvard y Smithsonian

Manténganse al tanto. El Telescopio Webb escaneará las atmósferas de planetas trapenses extremadamente intrigantes, siete mundos rocosos que existen en la zona de un sistema solar que no es ni demasiado caliente ni demasiado frío. En algunos de estos orbes, el agua puede salpicar la superficie.

Luce familiar?

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