Cosmicflows-4: Astronomers Assemble Largest Catalogue of 56,000 Galaxy Distances

Cosmicflows-4, a new catalogue of 56,000 galaxies, is the largest ever compilation of distances between the collections of stars, dust, and gas across the universe. Astronomers Brent Tully and Ehsan Kourkchi from the Institute for Astronomy used eight different methods to measure the distances to a whopping 56,000 galaxies. The catalogue is also being used to study how the galaxy moves.

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchiincludes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.

What is Cosmicflows-4:

Cosmicflows-4 is a catalogue or compilation of high precision galaxy distance it contains the catalogue of  54,000 galaxies in the universe. Galaxies beyond our immediate neighbourhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.

What is the outcome of Cosmicflows-4:

It helps us in Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth. With knowledge of the motions of galaxies in response to the mass around them, we can recreate the orbits that galaxies have followed since they were formed, giving us a better understanding of how the universe's vast, dark-matter-dominated structures have formed over time.

Brent Tully, an astronomer at the University of Hawaii at Manoa said "Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,". "Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few per cent."

 The researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team's study gives a value of H0=75 kilometres per second per megaparsec or Mpc (1 megaparsec = 3.26 million light years), with a very small statistical uncertainty of about 1.5 per cent.

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchiincludes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.

Astronomers have assembled a framework that shows the universe's age to be a little more than 13 billion years old, however, a dilemma of great significance has arisen in the details.

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