New data fuel debate on universe’s expansion rate
Quasar observations support higher value for Hubble constant
TWINKLING LIGHTS Five quasars, shown, helped scientists make a new measurement of the universe’s expansion rate.
ESA/Hubble, NASA, Suyu et al.
A new estimate of how fast the universe is expanding supports one side of an ongoing debate, favoring a more rapid expansion.
Observations of type 1a supernovas imply a faster expansion rate (known as the Hubble constant) than studies of the cosmic microwave background — light that originated early in cosmic history (SN: 8/6/2016, p. 10). Scientists with the H0LiCOW collaboration have now weighed in, using quasars, ultrabright light sources stirred up by supermassive black holes.
Supernova measurements indicate that distant galaxies are separating from one another by 73 kilometers per second for each megaparsec (about 3.3 million light-years) of distance between them. Cosmic microwave background experiments peg the number at 67 km/s per megaparsec. The new quasar measurement, 72 km/s per megaparsec,
