JHUAPL: Hubble Confirms Universe Expanding Faster Than Expected

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JHUAPL: Hubble Confirms Universe Expanding Faster Than Expected

Post by bystander » Sun Apr 28, 2019 6:30 pm

New Hubble Measurements Confirm Universe Is
Outpacing All Expectations of Its Expansion Rate

Johns Hopkins University Applied Physics Laboratory | 2019 Apr 25
New measurements from NASA’s Hubble Space Telescope confirm that the Universe is expanding about 9% faster than expected based on its trajectory seen shortly after the big bang, astronomers say.

The new measurements, published April 25 in Astrophysical Journal, reduce the chances that the disparity is an accident from 1 in 3,000 to only 1 in 100,000 and suggest that new physics may be needed to better understand the cosmos. ...

In this study, Riess and his SH0ES (Supernovae, H0, for the Equation of State) Team analyzed light from 70 stars in our neighboring galaxy, the Large Magellanic Cloud, with a new method that allowed for capturing quick images of these stars. The stars, called Cepheid variables, brighten and dim at predictable rates that are used to measure nearby intergalactic distances.

The usual method for measuring the stars is incredibly time-consuming; the Hubble can only observe one star for every 90-minute orbit around Earth. Using their new method called DASH (Drift And Shift), the researchers using Hubble as a “point-and-shoot” camera to look at groups of Cepheids, thereby allowing the team to observe a dozen Cepheids in the same amount of time it would normally take to observe just one.

With this new data, Riess and the team were able to strengthen the foundation of the cosmic distance ladder, which is used to determine distances within the Universe, and calculate the Hubble constant, a value of how fast the cosmos expands over time. ...

Latest Hubble Measurements Suggest Disparity
in Hubble Constant Calculations is not a Fluke

ESA Hubble Science Release | 2019 Apr 25

Mystery of the Universe's Expansion Rate Widens with New Hubble Data
NASA | GSFC | STScI | HubbleSite | 2019 Apr 25

Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination
of the Hubble Constant and Stronger Evidence for Physics Beyond ΛCDM
~ Adam G. Riess et al The Local Perspective on the Hubble Tension: Local Structure Does Not Impact
Measurement of the Hubble Constant
~ W. D'Arcy Kenworthy, Dan Scolnic, Adam Riess
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Hubble: New Measurement Adds to Mystery of Universe's Expansion Rate

Post by bystander » Tue Jul 16, 2019 4:42 pm

New Hubble Constant Measurement Adds
to Mystery of Universe’s Expansion Rate

NASA | GSFC | STScI | HubbleSite | 2019 Jul 16
STSCI-H-p1928a-z.jpg
These galaxies are selected from a Hubble Space Telescope program to measure the
expansion rate of the universe, called the Hubble constant. The value is calculated by
comparing the galaxies' distances to the apparent rate of recession away from Earth
(due to the relativistic effects of expanding space).

By comparing the apparent brightnesses of the galaxies' red giant stars with nearby
red giants, whose distances were measured with other methods, astronomers are able
to determine how far away each of the host galaxies are. This is possible because red
giants are reliable milepost markers because they all reach the same peak brightness in
their late evolution. And, this can be used as a "standard candle" to calculate distance.
Hubble's exquisite sharpness and sensitivity allowed for red giants to be found in the
stellar halos of the host galaxies.

The red giants were searched for in the halos of the galaxies. The center row shows
Hubble's full field of view. The bottom row zooms even tighter into the Hubble fields.
The red giants are identified by yellow circles.

Credits: NASA, ESA, W. Freedman (Univ of Chicago), ESO, Digitized Sky Survey

Astronomers have made a new measurement of how fast the universe is expanding, using an entirely different kind of star than previous endeavors. The revised measurement, which comes from NASA's Hubble Space Telescope, falls in the center of a hotly debated question in astrophysics that may lead to a new interpretation of the universe's fundamental properties.

Scientists have known for almost a century that the universe is expanding, meaning the distance between galaxies across the universe is becoming ever more vast every second. But exactly how fast space is stretching, a value known as the Hubble constant, has remained stubbornly elusive.

Now, University of Chicago professor Wendy Freedman and colleagues have a new measurement for the rate of expansion in the modern universe, suggesting the space between galaxies is stretching faster than scientists would expect. Freedman's is one of several recent studies that point to a nagging discrepancy between modern expansion measurements and predictions based on the universe as it was more than 13 billion years ago, as measured by the European Space Agency's Planck satellite.

As more research points to a discrepancy between predictions and observations, scientists are considering whether they may need to come up with a new model for the underlying physics of the universe in order to explain it. ...

In a new paper accepted for publication in The Astrophysical Journal, Freedman and her team announced a new measurement of the Hubble constant using a kind of star known as a red giant. Their new observations, made using Hubble, indicate that the expansion rate for the nearby universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance.

This measurement is slightly smaller than the value of 74 km/sec/Mpc recently reported by the Hubble SH0ES (Supernovae H0 for the Equation of State) team using Cepheid variables, which are stars that pulse at regular intervals that correspond to their peak brightness. This team, led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, Baltimore, Maryland, recently reported refining their observations to the highest precision to date for their Cepheid distance measurement technique. ...

New Measurement of Universe’s Expansion Rate Is “Stuck in the Middle”
Carnegie Institution for Science | 2019 Jul 16

New Measure of Hubble Constant Adds
to Mystery of Universe’s Expansion Rate

University of Chicago | 2019 Jul 16

The Carnegie-Chicago Hubble Program. VIII. An Independent Determination of the
Hubble Constant Based on the Tip of the Red Giant Branch
~ Wendy L. Freedman et al
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Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor