Hubble bubble may explain different measurements of expansion rate of the universe

Hubble bubble may explain different measurements of expansion rate of the universe:  One way to determine the Hubble constant... is based on measuring the cosmic microwave background radiation... can also be derived from the movement of galaxies near the Milky Way, movement largely due to the expansion of the universe. "When you compare the results from the two methods, there is a deviation of about 9 percent..."

...The bubble describes regions of the universe where the density of matter falls below the cosmic average. "Until now knowledge of our cosmic neighbourhood has been too imprecise to determine whether or not we are in such a bubble", continues Dr. Marra. "But let's just assume for a moment that our Milky Way is located in a Hubble Bubble. Matter outside the bubble would then attract nearby galaxies so strongly that they would move more quickly than average. In this case we would measure a higher Hubble constant that would apply to our cosmic neighbourhood, but not to the universe as a whole."

Using black holes to measure the Universe's rate of expansion

Using black holes to measure the Universe's rate of expansion: By adding together measurements of the amount of energy being emitted from the vicinity of the black hole to the amount of radiation which reaches Earth, it's possible to infer the distance to the black hole itself and the time in the history of the universe when the energy was emitted.
Getting an accurate estimate of the radiation being emitted depends on the properties of the black hole. For the specific type of black holes targeted in this work, the amount of radiation emitted as the object draws matter into itself is actually proportional to its mass, say the researchers. Therefore, long-established methods to measure this mass can be used to estimate the amount of radiation involved.

Planck shows almost perfect cosmos – plus axis of evil

Planck shows almost perfect cosmos – plus axis of evil: "The overall conclusion is that standard cosmology is an extremely good match to Planck data," said Efstathiou. "If I were an inflationary theorist I would be extremely happy."

...Planck reveals that one half of the universe has bigger variations than the other. Planck's detectors are over 10 times more sensitive and have about 2.5 times the angular resolution of WMAP's, giving cosmologists a much better look at this alignment. "We can be extremely confident that these anomalies are not caused by galactic emissions and not caused by instrumental effects..."

ScienceShot: A Better Cosmic Yardstick

ScienceShot: A Better Cosmic Yardstick: Now, astronomers have used observations of eight pairs of binary stars in the distant cluster to develop a new figure. The orbits of these pairs are aligned such that one star passes in front of the other as seen from Earth, which allowed the researchers to approximate the size of each member from the durations of the eclipses. The spectra of these cool, mature stars allowed the team to determine their surface temperatures. Together, those bits of data enabled the astronomers to estimate the amount of energy emitted by the stars, and that, in conjunction with observations of their actual brightness as seen from Earth, allowed the researchers to estimate the distance to each pair.

Speed of Universe's Expansion Measured Better Than Ever: Scientific American

Speed of Universe's Expansion Measured Better Than Ever: Scientific American: The new value reduces the uncertainty in the Hubble Constant to just 3 percent, and improves the precision of the measurement by a factor of three compared to a previous estimate from the Hubble Space Telescope...

Spitzer observed 90 cepheid stars, and was able to measure their apparent brightness more precisely than previous studies, leading the way to a more refined measurement of their distances, and the expansion rate of space.

A new way to measure the expansion of the universe

A new way to measure the expansion of the universe: By analysing light coming from a distant galaxy, the speed and direction of that galaxy can be easily measured. Determining the galaxy's distance from Earth is much more difficult. Until now, this has been done by observing the brightness of individual objects within the galaxy and using what we know about the object to calculate how far away the galaxy must be.
This approach to measuring a galaxy's distance from Earth is based on some well-established assumptions but is prone to systematic errors...
Galaxies are not spread evenly through space, but are clustered. Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early Universe, Mr Beutler has measured the Hubble constant with an uncertainly of less than 5%.*

New Study Gives Dark Energy A Boost - Science News

New Study Gives Dark Energy A Boost - Science News: Obtaining a precise value of the Hubble constant also places new restrictions on one alternative to “dark energy” as the driving force behind accelerated cosmic expansion, says Riess. In the alternative scenario, Earth and its environs would sit at the center of a vast void a few billion light-years across (SN: 6/7/08, p. 12). That configuration would produce an optical illusion making it appear as if the universe’s expansion is accelerating.
But such a setup would require a significantly lower value of the Hubble constant than the one Riess and his colleagues have now measured to high precision. Previous measurements of the constant were already at odds with the void model, but the added precision of the new study refutes the model conclusively, Riess says.