Plasma-based accelerators have demonstrated their ability to accelerate electrons at very high gradients (>100GeV/m). They have a number of niche applications. The AWAKE...
Mar17
Einstein first correctly predicted how mass deflects light. Galaxy clusters, comprising of up to hundreds of galaxies all residing in a still larger dark matter halo, act as excellent gravitational lenses. We present results from the James Webb Space Telescope (JWST) Prime Extragalactic Areas and Reionization and Lensing Science (PEARLS) program targeting galaxy cluster lenses. One point-source situated behind the galaxy cluster PLCK G165.7+67.0 (G165) appeared in three different locations as a result of lensing effects. Follow-up observations confirmed this source to be a distant Type Ia supernovae (SN) at a redshift of 1.783 that we call "SN H0pe." Differences in the path length to each image give rise to different photon arrival times. These "time delays," together with a gravitational lensing model, return a value for the Hubble-Lemaître constant "H0." Under double-blinded protocols, two time delays were measured by a photometric approach and a rare spectroscopic approach, and seven lens models were constructed. The time delays were augmented by measurements of the three absolute magnifications. By a scaled fit of the predicted values for these five observables relative to the measured set, a best-fit value was inferred of H0 = 75.7(+8.1)(-5.5) km/s/Mpc. This is only the second time H0 has been measured for a lensed supernova, and the first time using a standard candle. Regular monitoring of G165 and other galaxy cluster fields with similar properties may be well-rewarded by the detection of additional strongly-lensed SNe useful for Cosmology.
About Dr. Brenda Frye
Dr. Brenda Frye is an associate professor at the Department of Astronomy of the University of Arizona / Tucson and an an associate astronomer at the Steward Observatory. She received her PhD at the University of California / Berkeley. Her work concentrates on observing distant galaxy fields that are gravitationally lensed by massive clusters of galaxies along the line-of-sight. This lensing effect enables the study of distant galaxies that are intrinsically too faint to detect in the field. She searches for those cluster lenses by their rest-frame far-infrared colors, an approach that correlates with a high total star formation rate of galaxies in the background, and hence an increased probability of detecting a transient. One James Webb Space Telescope (JWST) program as Principle Investigator resulted in the rare discovery of a strongly-lensed standard candle useful for Cosmology, the Type Ia supernova,” SN H0pe.” SN H0pe is "photocopied" into three different locations, each one detected at a different time during its explosion. Measuring the difference in the arrival times resulted in an independent inference of the current rate of the expansion of the universe.
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