A Gravitational Wave Observatory on the Moon Could "Hear" 70% of the Observable Universe

Gravitational-wave astronomy is set to revolutionize our understanding of the cosmos. In only a few years it has significantly enhanced our understanding of black holes, but it is still a scientific field in its youth. That means there are still serious limitations to what can be observed.

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White Dwarf Measured Before it Exploded as a Supernova

Type Ia supernovae are an important tool for modern astronomy. They are thought to occur when a white dwarf star captures mass beyond the Chandrasekhar limit, triggering a cataclysmic explosion. Because that limit is the same for all white dwarfs, Type Ia supernovae all have about the same maximum brightness. Thus, they can be used as standard candles to determine galactic distances. Observations of Type Ia supernova led to the discovery of dark energy and that cosmic expansion is accelerating.

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Is the Hubble constant not…Constant?

Cosmologists have been struggling to understand an apparent tension in their measurements of the present-day expansion rate of the universe, known as the Hubble constant. Observations of the early cosmos – mostly the cosmic microwave background – point to a significantly lower Hubble constant than the value obtained through observations of the late universe, primarily from supernovae. A team of astronomers have dug into the data to find that one possible way to relieve this tension is to allow for the Hubble constant to paradoxically evolve with time. This result could point to either new physics…or just a misunderstanding of the data.

“The point is that there seems to be a tension between the larger values for late universe observations and lower values for early universe observation,” said Enrico Rinaldi, a research fellow in the University of Michigan Department of Physics and coauthor on the study. “The question we asked in this paper is: What if the Hubble constant is not constant? What if it actually changes?”

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Dark Energy Survey is out. 29 Papers Covering 226 Million Galaxies Across 7 Billion Light-Years of Space

Cosmology is now stranger to large scale surveys.  The discipline prides itself on data collection, and when the data it is collecting is about galaxies that are billions of years old its easy to see why more data would be better.  Now, with a flurry of 29 new papers, the partial results from the largest cosmological survey ever – the Dark Energy Survey (DES) – have been released.  And it largely confirms what we already knew.

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It Could be Possible to see Gravitational Wave Lenses

In February 2016, LIGO detected gravity waves for the first time. As this artist's illustration depicts, the gravitational waves were created by merging black holes. The third detection just announced was also created when two black holes merged. Credit: LIGO/A. Simonnet.

Gravitational-wave astronomy is very different from that of electromagnetic light. While gravitational waves are faint and difficult to detect, they also pass through matter with little effect. In essence, the material universe is transparent to gravitational waves. This makes gravitational wave astronomy a powerful tool when studying the universe. But it’s still in the early stages, and there is much to learn about how gravitational waves behave.

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A new Method Simulates the Universe 1000 Times Faster

Cosmologists love universe simulations.  Even models covering hundreds of millions of light years can be useful for understanding fundamental aspects of cosmology and the early universe.  There’s just one problem – they’re extremely computationally intensive.  A 500 million light year swath of the universe could take more than 3 weeks to simulate..  Now, scientists led by Yin Li at the Flatiron Institute have developed a way to run these cosmically huge models 1000 times faster.  That 500 million year light year swath could then be simulated in 36 minutes.

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