Conveners
[VC-O] Varying constants – astronomical observations
- Michael Murphy (Swinburne University of Technology)
[VC-O] Varying constants – astronomical observations
- Michael Murphy (Swinburne University of Technology)
In the last 15 years, studies of velocity shifts between metal transitions observed in high-resolution quasar spectra with the largest optical telescopes identified possible evidence for variation in the fine-structure constant, $\alpha$. Recent ‘supercalibration’ techniques have shown that these spectra likely have significant systematic distortions in their wavelength scales that undermine...
A new and fully-automated method is presented for the analysis of high-resolution absorption spectra (GVPFIT). The method has broad application but here we apply it specifically to the problem of measuring the fine structure constant at high redshift. For this we need objectivity and reproducibility. Three numerical methods are unified into one ``artificial intelligence'' process: a genetic...
ESPRESSO is a high-resolution-ultra-stable spectrograph for the VLT, whose commissioning will start in early 2017. One of its key science goals is to test the stability of nature’s fundamental couplings with unprecedented accuracy and control of possible
systematics. A total of 27 nights of the ESPRESSO Consortium’s guaranteed time observations (GTO) will be spent in testing the stability of...
Constraining variation in fundamental constants offers an important test for physics beyond the Standard Model.
The fine-structure constant (α) might not be constant throughout the universe. Models involving scalar fields coupled to α, the scalar charge depending on environment (e.g. on gravitational potential) naturally lead to α variation. White dwarf photospheres, where the...
We propose an improved methodology to constrain spatial variations of the fine structure constant using clusters of galaxies. We use the Planck 2013 data to measure the thermal Sunyaev-Zeldovich effect at the location of 618 X-ray selected clusters. We then use a Monte Carlo Markov Chain algorithm to obtain the temperature of the Cosmic Microwave Background at the location of our galaxy...
We investigate a new method to recover (if any) a possible varying speed of light (VSL) signal from cosmological data on an extended redshift range. We use mock cosmological data from future galaxy surveys (BOSS, DESI, WFirst-2.4 and SKA): the sound horizon at decoupling imprinted in the clustering of galaxies (BAO) as an angular diameter distance, and the expansion rate derived from those...
General relativity (GR) is the current tour de force of gravitation that passes all experimental scrutinies with great precision. However, the difficult in incorporating quantum principles motives alternative theories beyond GR. Some of these theories predict the breakdown of local Lorentz invariance. Standard-model extension (SME) is a convenient effective-theoretic framework to study such...
