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Category: cosmology – Page 110

A colorful, festive image sҺows different types of ligҺt containing tҺe remains of not one, but at least two exploded stars. TҺis supernova remnant is ƙnown as 30 Doradus B (30 Dor B for sҺort) and is part of a larger region of space wҺere stars Һave been continuously forming for tҺe past 8 to 10 million years. It is a complex landscape of darƙ clouds of gas, young stars, ҺigҺ-energy sҺocƙs, and superҺeated gas, located 160,000 ligҺt-years away from EartҺ in tҺe Large Magellanic Cloud, a small satellite galaxy of tҺe Milƙy Way.

TҺe new image of 30 Dor B was made by combining X-ray data from NASA’s CҺandra X-ray Observatory (purple), optical data from tҺe Blanco 4-meter telescope in CҺile (orange and cyan), and infrared data from NASA’s Spitzer Space Telescope (red). Optical data from NASA’s Hubble Space Telescope was also added in blacƙ and wҺite to ҺigҺligҺt sҺarp features in tҺe image.

A team of astronomers led by Wei-An CҺen from tҺe National Taiwan University in Taipei, Taiwan, Һave used over two million seconds of CҺandra observing time of 30 Dor B and its surroundings to analyze tҺe region. TҺey found a faint sҺell of X-rays tҺat extends about 130 ligҺt-years across. (For context, tҺe nearest star to tҺe sun is about four ligҺt-years away). TҺe CҺandra data also reveals tҺat 30 Dor B contains winds of particles blowing away from a pulsar, creating wҺat is ƙnown as a pulsar wind nebula.

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Astronomers from the Western Sydney University in Australia and elsewhere report the detection of a new pulsar wind nebula and a pulsar that powers it. The discovery, presented in a paper published Dec. 12 on the pre-print server arXiv, was made using the Australian Square Kilometer Array Pathfinder (ASKAP), as well as MeerKAT and Parkes radio telescopes.

Pulsar wind nebulae (PWNe) are nebulae powered by the wind of a pulsar. Pulsar wind is composed of charged particles; when it collides with the pulsar’s surroundings, in particular with the slowly expanding supernova ejecta, it develops a PWN.

Particles in PWNe lose their energy to radiation and become less energetic with distance from the central pulsar. Multiwavelength studies of these objects, including X-ray observations, especially using spatially-integrated spectra in the X-ray band, have the potential to uncover important information about particle flow in these nebulae. This could unveil important insights into the nature of PWNe in general.

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KENNEWICK — The LIGO Hanford Observatory near Richland is expected to detect 60% more cataclysmic cosmic events — like colliding neutron stars and black holes — thanks to a quantum limit breakthrough.

Since the observatory was turned back on in May after three years of upgrades, including adding new quantum squeezing technology, it can probe a larger volume of the universe.

“Now that we have surpassed this quantum limit, we can do a lot more astronomy,” said Lee McCuller, assistant professor of physics at the California Institute of Technology and a leader in the study published in the journal “Physical Review X.”

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The mini-halos of dark matter scattered throughout the cosmos could function as highly sensitive probes of primordial magnetic fields. This is what emerges from a theoretical study conducted by SISSA and published in Physical Review Letters.

Present on immense scales, magnetic fields are found everywhere in the universe. However, their origin is still a subject of debate among scholars. An intriguing possibility is that magnetic fields originated near the birth of the universe itself; that is, they are primordial magnetic fields.

In the study, the researcher showed that if magnetic fields are indeed primordial then it could cause an increase in dark matter density perturbations on small scales. The ultimate effect of this process would be the formation of mini-halos of dark matter, which, if detected, would hint towards a primordial nature of magnetic fields. Thus, in an apparent paradox, the invisible part of our universe could be useful in resolving the nature of a component of the visible one.

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A team of researchers has analyzed more than one million galaxies to explore the origin of the present-day cosmic structures, reports a recent study published in Physical Review D as an Editors’ Suggestion.

Until today, precise observations and analyses of the cosmic microwave background (CMB) and large-scale structure (LSS) have led to the establishment of the standard framework of the universe, the so-called ΛCDM model, where cold dark matter (CDM) and dark energy (the cosmological constant, Λ) are significant characteristics.

This model suggests that primordial fluctuations were generated at the beginning of the universe, or in the early universe, which acted as triggers, leading to the creation of all things in the universe including stars, galaxies, galaxy clusters, and their spatial distribution throughout space. Although they are very small when generated, fluctuations grow with time due to the gravitational pulling force, eventually forming a dense region of dark matter, or a halo. Then, different halos repeatedly collided and merged with one another, leading to the formation of celestial objects such as galaxies.

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In a public lecture titled “The Meaning of Spacetime,” renowned physicist Juan Maldacena outlined ideas that arose from the study of quantum aspects of black holes.

V/ Perimeter Institute

On July 27, Juan Maldacena, a luminary in the worlds of string theory and quantum gravity, will share his insights on black holes, wormholes, and quantum entanglement.

Continue reading “The Meaning of Spacetime: Juan Maldacena public lecture webcast” | >

This whirling image features a bright spiral galaxy known as MCG-01–24-014, which is located about 275 million light-years from Earth. In addition to being a well-defined spiral galaxy, MCG-01–24-014 has an extremely energetic core known as an active galactic nucleus (AGN) and is categorized as a Type-2 Seyfert galaxy.

Seyfert galaxies, along with quasars, host one of the most common subclasses of AGN. While the precise categorization of AGNs is nuanced, Seyfert galaxies tend to be relatively nearby and their central AGN does not outshine its host, while quasars are very distant AGNs with incredible luminosities that outshine their host galaxies.

There are further subclasses of both Seyfert galaxies and quasars. In the case of Seyfert galaxies, the predominant subcategories are Type-1 and Type-2. Astronomers distinguish them by their spectra, the pattern that results when light is split into its constituent wavelengths. The spectral lines that Type-2 Seyfert galaxies emit are associated with specific ‘forbidden’ emission lines. To understand why emitted light from a galaxy could be forbidden, it helps to understand why spectra exist in the first place.

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ESA’s Euclid mission is on a quest to unveil the nature of two elusive ‘dark’ entities. As the renowned theoretical physicist Stephen Hawking remarked in 2013, “The missing link in cosmology is the nature of dark matter and dark energy”

During the last 70 years, scientists have made enormous progress in understanding the very initial phases of the Universe and its evolution to the present day. Thanks to advances in observations and theoretical modelling, a clear picture has emerged of how stars form, and how galaxies grow and interact with each other, coming together to form groups and clusters.

Yet, fundamental mysteries remain. 95% of the Universe appears to be made up of unknown ‘dark’ matter and energy. Dark matter and energy affect the motion and distribution of visible sources but do not emit, reflect or absorb any light. And scientists do not know what these dark entities actually are.

To address this question, Euclid will create a great map of the large-scale structure of the Universe across space and time by observing with unprecedented accuracy billions of galaxies out to 10 billion light-years. This is not easy, and making sure that Euclid is up to the task has required the expertise and dedication of many people over several years of work.

Continue reading “Euclid: Gate to the dark” | >