arXiv subjects

M. Porru

Publications and source records attributed to M. Porru.

4 recordsLinked to original sources

arXiv2024

End-to-End simulation framework for astronomical spectrographs: SOXS, CUBES and ANDES

We present our numerical simulation approach for the End-to-End (E2E) model applied to various astronomical spectrographs, such as SOXS (ESO-NTT), CUBES (ESO-VLT), and ANDES (ESO-ELT), covering multiple wavelength regions. The E2E model aim at simulating the expected astronomical observations starting from the radiation of the scientific sources (or calibration sources) up to the raw-frame data produced by the detectors. The comprehensive description includes E2E architecture, computational models, and tools for rendering the simulated frames. Collaboration with Data Reduction Software (DRS) teams is discussed, along with efforts to meet instrument requirements. The contribution to the cross-correlation algorithm for the Active Flexure Compensation (AFC) system of CUBES is detailed.

astro-ph.IM↗

arXiv2024

Progress on FORS-Up: the first instrument using ELT technologies

ESO is in the process of upgrading one of the two FORS (FOcal Reducer/low dispersion Spectrograph) instruments - a multi-mode (imaging, polarimetry, long-slit, and multi-object spectroscopy) optical instrument mounted on the Cassegrain focus of Unit Telescope 1 of ESO's Very Large Telescope. FORS1 was moved from Chile to Trieste, and is undergoing complete refurbishment, including the exchange of all motorised parts. In addition, new software is developed, based on the Extremely Large Telescope Instrument Control Software Framework, as the upgraded FORS1 will be the first instrument in operations to use this framework. The new Teledyne e2V CCD has now been procured and is undergoing testing with the New Generation Controller at ESO. In addition, a new set of grisms have been developed, and a new set of filters will be purchased. A new internal calibration unit has been designed, making the operations more efficient.

astro-ph.IM↗

arXiv2023

Crossing the Rubicon of Reionization with z~5 QSOs

One of the key open questions in Cosmology is the nature of the sources that completed the cosmological hydrogen Reionization at z~5.2. High-z primeval galaxies have been long considered the main drivers for Reionization, with a minor role played by high-z AGN. However, in order to confirm this scenario, it is fundamental to measure the photo-ionization rate produced by active SMBHs close to the epoch of Reionization. Given the pivotal role played by spectroscopically complete observations of high-z QSOs, in this paper we present the first results of the RUBICON (Reionizing the Universe with BrIght COsmological Nuclei) survey. It consists of a color selected sample of bona-fide z~5 QSO candidates from the Hyper Suprime-Cam Subaru Strategic Survey. Our QSO candidates have been validated both by photometric redshifts based on SED fitting and by spectroscopic redshifts, confirming that they lie at 4.5<z_spec<5.2. A relatively large space density of QSOs (Phi~1.4x10^-8 cMpc^-3) is thus confirmed at z~5 and M1450~-27, consistent with a pure density evolution of the AGN luminosity function from z=4 to z=5, with a mild density evolution rate of 0.25 dex. This indicates that AGN could play a non-negligible role in the cosmic Reionization. The Rubicon of Reionization has been crossed.

astro-ph.GA↗

arXiv2023

Spectrographs and Spectroscopists for the Sandage Test

The redshift drift is a small, dynamic change in the redshift of objects following the Hubble flow. Its measurement provides a direct, real-time, model-independent mapping of the expansion rate of the Universe. It is fundamentally different from other cosmological probes: instead of mapping our (present-day) past light-cone, it directly compares different past light-cones. Being independent of any assumptions on gravity, geometry or clustering, it directly tests the pillars of the Lambda-CDM paradigm. Recent theoretical studies have uncovered unique synergies with other cosmological probes, including the characterization of the physical properties of dark energy. At the time of the original proposal by Sandage (1962) the expected change in the redshift of objects at cosmological distances appeared to be exceedingly small for reasonable observing times and beyond technological capabilities. In the last decades progress in the spectrographs (e.g. ESPRESSO), in the collecting area of telescopes and in the samples of cosmic beacons, enabled by new datasets and new machine-learning-based selections, have drastically changed the situation, bringing the Redshift Drift Grail within reach. As a consequence, this measurement is a flagship objective of the Extremely Large Telescope (ELT), specifically of its high-resolution spectrograph, ANDES.

astro-ph.CO↗