Comparing Galaxy Clustering in Horizon-AGN Simulated Lightcone Mocks and VIDEO Observations
Enhanced fluorescence from x-ray line coincidence pumping of K-pumped Cl and Mg-pumped Ge plasmas
Abstract:
Many resonant photo-pumped X-ray laser schemes that use a strong pump line such as Ly-α or He-α to populate the upper laser state of a separate lasing material have been proposed over the last four decades but none have been demonstrated. As a first step to creating a photo-pumped X-ray laser we decided to reinvestigate some of these schemes at the Orion laser facility with the goal to demonstrate enhanced fluorescence as a first step toward creating a laser. In particular we look at using the Ly-α or He-α K lines to pump the 1s – 3p and 4p transitions in H-like Cl and see fluorescence on the 4f -3d line at 65 Å and the 3d – 2p line at 23 Å. Preliminary experiments are presented that show a modest enhancement of 40% on the 3d-2p line. As an alternative we also look at enhancing the 2p – 2s line in Ne-like Ge at 65Å using the Ly-α Mg line to photo-pump the 2s – 3p line of Ne-like Ge. Calculations are presented that suggest modest enhancements of 2.5 and recent experiments will be presented that show emission from a Ge plasma pumped by the Ly-α Mg line.HORIZON-AGN virtual observatory – 2. Template-free estimates of galaxy properties from colours
Abstract:
Using the HORIZON-AGN hydrodynamical simulation and self-organizing maps (SOMs), we show how to compress the complex, high-dimensional data structure of a simulation into a 2D grid, which greatly facilitates the analysis of how galaxy observables are connected to intrinsic properties. We first verify the tight correlation between the observed 0.3–5 μm broad-band colours of HORIZON-AGN galaxies and their high-resolution spectra. The correlation is found to extend to physical properties such as redshift, stellar mass, and star formation rate (SFR). This direct mapping from colour to physical parameter space still works after including photometric uncertainties that mimic the COSMOS survey. We then label the SOM grid with a simulated calibration sample to estimate redshift and SFR for COSMOS-like galaxies up to z ∼ 3. In comparison to state-of-the-art techniques based on synthetic templates, our method is comparable in performance but less biased at estimating redshifts, and significantly better at predicting SFRs. In particular, our ‘data-driven’ approach, in contrast to model libraries, intrinsically allows for the complexity of galaxy formation and can handle sample biases. We advocate that observations to calibrate this method should be one of the goals of next-generation galaxy surveys.