arXiv subjects

Leonardo Trobbiani

Publications and source records attributed to Leonardo Trobbiani.

5 recordsLinked to original sources

arXiv2026

A pilot sample of Planck-selected strongly lensed sub-mm galaxies: NOEMA observations and physical characterisation

The extreme brightness of high-$z$ strongly lensed galaxies detected by Planck surveys, thanks to their exceptionally large gravitational magnifications, offers a unique opportunity to investigate in extraordinary detail their structure and kinematics during their active star-formation phase. As a step in this direction, we present and analyse NOEMA imaging and spectroscopic data for four lensed high-z galaxy candidates. We performed continuum and line imaging of the sources at 2 and 3 mm bands down to $1''.2$ spatial resolution and 40 $\rm{km}\,{\rm s}^{-1}$ spectral resolution, reconstructed and fitted the line profiles, and produced moment maps of the line emission to investigate the spatial distribution and kinematics of the molecular gas. We also carried out the gravitational lens modelling for one of the sources. The continuum images showed multiple components for at least two of the sources, strongly supporting the strong lensing scenario. We detected with high S/N ratios two CO lines for all sources, at CO(3-2), CO(4-3) and CO(5-4) transitions; for one source, we also detected the [CI](1-0) line. We derived accurate spectroscopic redshifts $2.3 \lesssim z \lesssim 3.3$, with $1\sigma$ uncertainties $\delta z \approx 10^{-4}$ in redshift. All four sources lie well above the CO line luminosity-linewidth relation for unlensed galaxies, providing independent confirmation of their strongly lensed nature. Three sources exhibit broad (FWHM$\gtrsim 400\,{\rm km}\,{\rm s}^{-1}$), double-peaked line profiles and substantial velocity gradients, while the last one shows relatively narrow, single-peaked lines and no detectable velocity gradients, possibly indicating a nearly face-on geometry or intrinsically simple kinematics.

astro-ph.GA↗

arXiv2025

ALMACAL. XV. Band 3 ALMA Survey and Number Counts

The ALMACAL project leverages ALMA maps of calibrator-centered fields to conduct deep mm/sub-mm surveys, enabling the detection of extragalactic sources with flux densities orders of magnitude fainter than achievable with other instruments. These faint sources are critical for refining evolutionary models, as their number counts provide key constraints. In this study, we analyzed band-3 ALMACAL maps from 606 calibrator fields, employing a novel machine learning approach to mitigate the often-overlooked bias introduced by the calibrator itself. Supported by extensive simulations, we extended 100 GHz radio AGN counts by approximately 1.5 orders of magnitude in flux density and refined constraints on dusty star-forming galaxies, reaching sensitivities as low as $\sim$180 $\mu$Jy. We have improved the sampling, compared to previous results, in the region of the dominant population transition (between dusty star-forming galaxies and radio AGN). Our results are in good agreement with model predictions.

astro-ph.GA↗

arXiv2025

Using Planck maps for a systematic search of ultra-bright high-redshift strongly lensed galaxies

This paper presents a novel approach to the use of Planck telescope data for the systematic search of ultra-bright high-redshift strongly lensed galaxies. These galaxies provide crucial insights into the early universe, particularly during phases of intense star formation. The Planck mission, despite its limited angular resolution, offers a unique opportunity to identify candidate strongly lensed galaxies over a wide area of the sky. This work outlines the methodology used to identify these rare objects, the challenges encountered, and the preliminary results obtained from follow-up observations with higher-resolution instruments.

astro-ph.GA↗

arXiv2025

AMICO-WL: an optimal filtering algorithm for galaxy cluster detections with weak lensing

The detection of galaxy clusters, the most massive bounded structures in the universe, is crucial for cosmological analysis. Weak lensing signals allow us to track the distribution of all (dark and baryonic) matter regardless of its observable electromagnetic properties. Upcoming wide-field surveys like Euclid and LSST-Rubin will provide enhanced shape measurements of billions of background galaxies, presenting an unparalleled opportunity to detect galaxy clusters on a vast cosmic scale. The immense data volume generated by these surveys will require efficient and accurate analysis techniques. In this work, we introduce AMICO-WL, an extension of the optimal filtering algorithm implemented in AMICO, a well-tested code developed for optical cluster detection. AMICO-WL implements a specific linear optimal matched filter for weak lensing data in the AMICO infrastructure, using parallelisation and adding an efficient signal-to-noise ratio thresholding approach to set a desired sample purity and a cleaning procedure to deal with blended detections. The algorithm has been tested on a 25 deg$^2$ field of Euclid-like mock galaxy catalogue with the simulated shear signal produced using DUSTGRAIN-$pathfinder$ past-light-cones. We implemented a foreground removal procedure based on different cuts of low redshift galaxies from the input catalogue. To evaluate the performance of the method, we used an efficient matching procedure based on the 'blinking' of the simulation's individual redshift lensing planes. Cross-matching the AMICO-WL detections with the dark matter halo sample in the simulation having $M_{200} > 5 \times 10^{13}$ $M_{\odot}/h$ and considering a purity level of $\sim70\%$, the application of the foreground removal doubles the completeness from $6.5\%$ to $13.0\%$ and at the same time produces a significant decrease of spurious detections.

astro-ph.CO↗

arXiv2024

Correlations between IR Luminosity, Star Formation Rate, and CO Luminosity in the Local Universe

We exploit the DustPedia sample of galaxies within approximately 40 Mpc, selecting 388 sources, to investigate the correlations between IR luminosity (L$_{\rm IR}$), the star formation rate (SFR), and the CO(1-0) luminosity (L$_{\rm CO}$) down to much lower luminosities than reached by previous analyses. We find a sub-linear dependence of the SFR on L$_{\rm IR}$. Below $\log(\hbox{L}_{\rm IR}/\hbox{L}_\odot)\simeq 10$ or $\hbox{SFR}\simeq 1\,\hbox{M}_\odot\,\hbox{yr}^{-1}$, the SFR/L$_{\rm IR}$ ratio substantially exceeds the standard ratio for dust-enshrouded star formation, and the difference increases with decreasing L$_{\rm IR}$ values. This implies that the effect of unobscured star formation overcomes that of dust heating by old stars, at variance with results based on the $\textit{Planck}$ ERCSC galaxy sample. We also find that the relations between the L$_{\rm CO}$ and L$_{\rm IR}$ or the SFR are consistent with those obtained at much higher luminosities.

astro-ph.GA↗