The Mystery of Alpha and the Isotopes

We report unbiased AI measurements of the fine structure constant alpha in two proximate absorption regions in the spectrum of the quasar HE0515-4414. The data are high resolution, high signal to noise, and laser frequency comb calibrated, obtained using the ESPRESSO spectrograph on the VLT. The high quality of the data and proximity of the regions motivate a differential comparison, exploring the possibility of spatial variations of fundamental constants, as predicted in some theories. We show that if the magnesium isotopic relative abundances are terrestrial, the fine structure constants in these two systems differ at the 7-sigma level. A 3-sigma discrepancy between the two measurements persists even for the extreme non-terrestrial case of 100% ^{24}Mg, if shared by both systems. However, if Mg isotopic abundances take independent values in these two proximate systems, one terrestrial, the other with no heavy isotopes, both can be reconciled with a terrestrial alpha, and the discrepancy between the two measurements falls to 2-sigma. We discuss varying constant and varying isotope interpretations and resolutions to this conundrum for future high precision measurements.Comment: 6 pages, 3 figure

The XXL Survey XVIII. ATCA 2.1 GHz radio source catalogue and source counts for the XXL-South field

The 2.1 GHz radio source catalogue of the 25 deg(2) ultimate XMM extragalactic survey south (XXL-S) field, observed with the Australia Telescope Compact Array (ATCA), is presented. The final radio mosaic achieved a resolution of similar to 4.8" and a median rms noise of sigma approximate to 41 mu Jy/beam. To date, this is the largest area radio survey to reach this flux density level. A total of 6350 radio components above 5 sigma are included in the component catalogue, 26.4% of which are resolved. Of these components, 111 were merged together to create 48 multiple-component radio sources, resulting in a total of 6287 radio sources in the source catalogue, 25.9% of which were resolved. A survival analysis revealed that the median spectral index of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is alpha = 0.75, consistent with the values of -0.7 to -0.8 commonly used to characterise radio spectral energy distributions of active galactic nuclei. The 2.1 GHz and 1.4 GHz di ff erential radio source counts are presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts show good agreement with the other surveys

Analysis of HARPS Astro-Comb data

"The HARPS astro-comb was repaired in October 2016, and it is under unsupervised operations since. In this poster we show the analysis of the comb data, in particular the presence of a wavelength dependent background \ncontinuum. We are able to characterise this background with respect to wavelength and time. We show that its proper evaluation is essential to optimize the performances of the system.

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant $H_0$, the $\sigma_8$--$S_8$ tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the $5.0\,\sigma$ tension between the {\it Planck} CMB estimate of the Hubble constant $H_0$ and the SH0ES collaboration measurements. After showing the $H_0$ evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the {\it Planck} CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density $\Omega_m$, and the amplitude or rate of the growth of structure ($\sigma_8,f\sigma_8$). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the $H_0$--$S_8$ tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals.[Abridged]Comment: Contribution to Snowmass 2021. 224 pages, 27 figures. Accepted for publication in JHEA