The National Institute for Astrophysics (Italian: Istituto Nazionale di Astrofisica, or INAF) is an Italian research institute in astronomy and astrophysics, founded in 1999. INAF funds and operates twenty separate research facilities, which in turn employ scientists, engineers and technical staff. The research they perform covers most areas of astronomy, ranging from planetary science to cosmology.
We present a new method to estimate the spectral resolution of a radio data cube from its noise properties. We assume that the data cube is the result of the convolution of a spectrally-uncorrelated cube with a constant convolution kernel K. We demonstrate that K and the resolution, defined as K's integral, can be estimated thanks to the analytical relation between the autocorrelation of the noise spectra extracted from the cube and the power spectrum of the kernel. We discuss a number of algorithms that make this method robust in the realistic case of a finite number of spectra and channels, real signal and artefacts, and we present the results obtained for a number of datasets from the literature. We further highlight that this method is applicable to any data cube that meets our assumptions independently of the observing frequency or the exact nature of the cube's "third" axis, e.g., it could be used to measure the time resolution of transient-search data cubes. We make this method available as part of the open-source software tool spectre.
Measuring galaxy rotation curves is critical for inferring the properties of dark-matter haloes in the Lambda cold dark matter (Lambda CDM) paradigm. We present HI rotation curves and mass models for 20 galaxies from the MIGHTEE survey. Using extended H I kinematics, we construct resolved mass models that include stellar, gaseous, and dark-matter components. Stellar masses are derived using 3.6 mu m imaging under fixed mass-to-light ratio (Upsilon(*) = M/L) assumptions and are complemented, for the first time for a H I-selected sample, by spatially resolved M/L, obtained from multiwavelength spectral energy distribution fitting. We examine the ratio of baryonic to observed rotation velocity (V-bar/V-obs) at the characteristic radius R-2.2. Adopting a fixed Upsilon(*) = 0.5M((R))/L-(R) yields a clear dependence of V-2.2 /V-obs on galaxy luminosity, while adopting Upsilon(*) = 0.2M((R))/L-(R) substantially weakens this trend. In contrast, the resolved M/L analysis preserves the luminosity dependence while modifying the stellar contribution on a galaxy-by-galaxy basis, providing a more accurate representation of the underlying relation. We model the dark-matter haloes using Navarro-Frenk-White profiles and find that the different assumptions for a fixed a M/L systematically shift galaxies relative to the theoretical stellar-to-halo mass and baryonic-to-halo mass relations, while the spatially varying M/L yields the closest agreement with theoretical benchmarks within Lambda CDM. We therefore demonstrate that future investigations of the dark matter properties of galaxies using rotation curves need to account for varying M/L across individual galaxy profiles and between galaxies in order to obtain accurate measurements of the dark matter, and therefore test Lambda CDM.
Floor-Fractured Craters (FFCs) are complex impact structures characterized by fractures, mesas, and knobs on their floors. They appear extensively on Mars, exhibiting diverse morphologies indicative of multiple geological processes including tectonic, volcanic, glacial, and fluvial mechanisms. This study presents a high-resolution geomorphological analysis of Hala crater, an 18 km-diameter FFC located within the Gorgonum Chaos Basin, in Terra Sirenum. Utilizing high-resolution imagery from HiRISE, CaSSIS, and topographic data from HRSC-derived DTMs, we compile a geomorphological map at a scale of 1:25,000. Detailed morphometric analyses reveal the crater is anomalously shallow compared to neighbouring structures, implying significant infill processes possibly influenced by magmatic intrusion and localized uplift events. The alignment of fractures within the crater notably correlates with regional tectonic stresses from the Sirenum Fossae system, suggesting substantial structural control. Periglacial landforms further illustrate extensive modification by ice-related processes during the Amazonian. Overall, our detailed geomorphological mapping highlights a complex interplay of impact-driven, tectonic, volcanic, and periglacial processes that have shaped the crater's interior. This analysis contributes to our understanding of the geological history of FFCs.
We present a new climatology of Martian water vapor column abundance derived from nadir dayside observations made by the Nadir and Occultation for MArs Discovery (NOMAD) instrument suite as part of the ExoMars Trace Gas Orbiter (TGO) mission. H2O vertical column densities are retrieved by applying an Optimal Estimation inversion scheme to the near-infrared reflectance factor spectra acquired by the NOMAD Limb, Nadir and Occultation (LNO) channel over Martian Years 34-38 (April 2018-June 2025). By correcting for saturated absorption lines and using an improved Acousto-Optical Tunable Filter (AOTF) calibration, H2O vertical columns retrieved from diffraction orders 167 and 169 quantitatively agree with co-located MGS/TES (Thermal Emission Spectrometer) and EMM/EMIRS (Emirates Mars Infrared Spectrometer) independent observations, in terms of seasonal and latitudinal variations. A good agreement is also obtained with the GEM-Mars General Circulation Model, except at high northern latitudes during the Aphelion season, where the current GEM-Mars version underestimates the H2O summer peak. The geographical distribution of the retrieved H2O column abundances is characterized over the different Martian seasons and shows the typical patterns observed by previous space-borne infrared instruments, such as the Pole-to-Pole transport and some local enhancements correlated with the topography. Our retrievals nevertheless indicate a more marked difference between Northern and Southern Hemisphere H2O column summer peaks. The seasonal cycle is also found to be stable from year-to-year, except during and after the Martian Year 34 global dust storm, where significantly smaller column abundances are observed compared to the same period in Martian Years 35-37.
Measuring the density profile and mass concentration of dark-matter haloes is a key test of the standard cold dark matter paradigm. Such objects are dark and thus challenging to characterize, but they can be studied via gravitational lensing. Recently, a million-solar-mass object was discovered superposed on an extended and extremely thin gravitational arc. Here we report on extensive tests of various assumptions for the mass density profile and redshift of this object. We find that models that best describe the data have two components: an unresolved point mass of radius ≤10 pc centred on an extended mass distribution with an almost constant surface density out to a truncation radius of 139 pc. These properties do not resemble any known astronomical object. However, if the object is dark matter dominated, its structure is incompatible with cold dark matter models but may be compatible with a self-interacting dark-matter halo where the central region has collapsed to form a black hole. This detection could thus carry substantial implications for our current understanding of dark matter. Gravitational lens modelling of a million-solar-mass dark object reveals that it cannot be a free-floating black hole or dark-matter halo as predicted by cold dark matter, instead indicating a peculiar and highly concentrated mass distribution.
