Institute for Fundamental Physics of the Universe

We investigate the kinematic properties of the Coma galaxy cluster using a new, large spectroscopic sample of member galaxies, from the Dark Energy Spectroscopic Instrument (DESI). By means of the MG-MAMPOSSt code, based on the Jeans equation, we jointly reconstruct the total cluster mass profile and the velocity anisotropy profile. Assuming a Navarro-Frenk-White model, we estimate a virial mass $M_{200}=1.04_{-0.08}^{+0.07}~({\rm stat})\pm 0.09~({\rm syst})\times 10^{15}\,\mathrm{M}_\odot $, corresponding to $r_{200}=2.07 \pm 0.05\,\mathrm{Mpc}$ and a scale radius for the mass profile $r_{\rm s}=0.73^{+0.24}_{-0.30}\,\mathrm{Mpc}$, which provides the tightest robust kinematic mass profile constraint to date. By considering separately the mass of the hot gas and the galaxy stellar mass, we determine the dark matter mass profile, with $M_{200}^{\rm DM}=8.6^{+1.2}_{-0.8}\times 10^{14}\,\text{M}_\odot$. We discuss the impact of the mass and number density parametrisations, the effect of different choices of the cluster's rest frame and of the radial range of the kinematic analysis, further comparing our results with previous estimates from the literature. The cluster dynamical state has also been assessed, using the spatial and line-of-sight velocity distributions of the members. We perform a kinematic study of different subsamples of galaxy populations, based on their colour (red sequence, green valley, and blue cloud), focusing on the anisotropy profiles and line-of-sight velocity distributions. The orbits of green valley and blue cloud galaxies appear to be more radial in the centre and in the outskirts, respectively, with the latter predicting a higher cluster virial mass. This study provides new insights on the interplay between dynamical and intrinsic properties of galaxies in massive structures, fundamental to verify the tight connection between galaxy evolution and environment.

Abstract The XRISM Resolve X-ray spectrometer makes it possible to gain detailed insights into the gas motions of the intracluster medium (ICM) of galaxy clusters. Current simulation studies focus mainly on statistical comparisons, making the comparison to the currently still small number of clusters difficult due to unknown selection effects. This study aims to bridge this gap, using simulated counterparts of Coma, Virgo, and Perseus from the SLOW constrained simulations. These clusters show excellent agreement in their properties and dynamical state with observations, thus providing an ideal testbed to understand the processes shaping the properties of the ICM. We find that the simulations match the order of the amount of turbulence for the three considered clusters, Coma being the most active, followed by Perseus, while Virgo is very relaxed. Typical turbulent velocities are a few hundred km s −1 , very close to observed values. The resulting turbulent pressure support is ≈1% for Virgo, ≈6% for Perseus, and ≈8% for Coma within the central 1%–2% of R 200 . Compared to previous simulations and observations, measured velocities and turbulent pressure support are on average lower, in line with XRISM findings, thus indicating the importance of selection effects.

The extragalactic background light (EBL) fluctuations in the optical/near-IR encode the cumulative integrated galaxy light (IGL), diffuse intra-halo light (IHL), and high-$z$ sources from the epoch of reionisation (EoR), but they are difficult to disentangle with auto-spectra alone. We aim to decompose the EBL into its principal constituents using multi-band intensity mapping combined with cosmic shear and galaxy clustering. We develop a joint halo-model framework in which IHL follows a mass- and redshift-dependent luminosity scaling, IGL is set by an evolving Schechter luminosity function, and EoR emission is modelled with Pop II/III stellar emissivities and a binned star-formation efficiency. Using mock surveys in a flat $Λ$CDM cosmology with ten spectral bands spanning 0.75-5.0$\rm μm$ in the NEP deep fields over about 100$°^2$ with source detections down to AB=20.5 for masking, and six redshift bins to $z=2.5$, we fit auto- and cross-power spectra using a MCMC method. The combined SPHEREx$\times$Euclid analysis recovers all fiducial parameters within 1$σ$ and reduces 1$σ$ uncertainties on IHL parameters by 10-35% relative to SPHEREx EBL-only, while EoR star-formation efficiency parameters improve by 20-35%. Cross-correlations reveal a stronger coupling of IHL than IGL to the shear field, enhancing component separation; conversely, the EoR contribution shows negligible correlation with cosmic shear and galaxy clustering, aiding its isolation in the EBL. Relative to the SPHEREx EBL-only case, the inferred IHL fraction as a function of halo mass is significantly tightened over $10^{11}-10^{14} M_{\odot}$, with uncertainties reduced by 5-30%, and the resulting star-formation rate density constraints extend to $z\sim 11$, with uncertainty reductions of 22-31%.

The ongoing Euclid mission aims to measure spectroscopic redshifts for approximately two million galaxies using the H $α$ line emission detected in near-infrared slitless spectroscopic data from the Euclid Deep Fields (EDFs). These measurements will reach a flux limit of $5\times 10^{-17}\,{\rm erg}\,{\rm cm}^{-2}\,{\rm s}^{-1}$ in the redshift range $0.4<z<1.8$, opening the door to numerous investigations involving galaxy evolution, extending well beyond the mission's core objectives. The achieved H $α$ luminosity depth will lead to a sufficiently high sampling, enabling the reconstruction of the large-scale galaxy environment. We assess the quality of the reconstruction of the galaxy cosmic web environment with the expected spectroscopic dataset in EDFs. The analysis is carried out on the Flagship and GAEA galaxy mock catalogues. The quality of the reconstruction is first evaluated using geometrical and topological statistics measured on the cosmic web, namely the length of filaments, the area of walls, the volume of voids, and its connectivity and multiplicity. We then quantify how accurately gradients in galaxy properties with distance from filaments can be recovered. As expected, the small-scale redshift-space distortions, have a strong impact on filament lengths and connectivity, but can be mitigated by compressing galaxy groups before skeleton extraction. The cosmic web reconstruction is biased when relying solely on H $α$ emitters. This limitation can be mitigated by applying stellar mass weighting during the reconstruction. However, this approach introduces non-trivial biases that need to be accounted for when comparing to theoretical predictions. Redshift uncertainties pose the greatest challenge in recovering the expected dependence of galaxy properties, though the well-established stellar mass transverse gradients towards filaments can still be observed.

Weak lensing surveys require accurate correction for the point spread function (PSF) when measuring galaxy shapes. For a diffraction-limited PSF, as arises in space-based missions, this correction depends on each galaxy SED. In the Euclid mission, galaxy SED reconstruction, a tasks of the photometric-redshift processing function (PHZ PF), relies on broad- and medium-band ancillary photometry. The limited wavelength sampling of the Euclid VIS passband and signal-to-noise ratio may affect the reconstruction accuracy and translate into biases in the weak lensing measurements. In this study, we present the methodology, which is employed in the Euclid PHZ PF, for reconstructing galaxy SEDs at 55 wavelengths, sampling the VIS passband every 10 nm, and we assess whether it fulfils the accuracy requirements imposed on the Euclid PSF model. We employ both physics- and data-driven methods, focusing on a new approach of template-based flux correction and Gaussian processes, and we introduce an SED metric whose bias propagates into PSF quadrupole moment errors. Our findings demonstrate that Gaussian processes and template fitting meet the requirements only in specific, but complementary, redshift intervals. We therefore propose a hybrid approach, which leverages both methods. This solution proves to be effective in meeting the Euclid accuracy requirements for most of the redshift range of the survey. Finally, we investigate the impact on the SED reconstruction of a new set of 16 evenly-spaced medium-band filters for the Subaru telescope, providing quasi-spectroscopic coverage of the VIS passband. This study shows promising results, ensuring accurate SED reconstruction and meeting the mission PSF requirements. This work thus provides not only the methodological foundation of galaxy SED reconstruction in the Euclid PHZ PF, but also a roadmap for future improvements using a new medium-band survey.

We explore the constraining power of future 21cm intensity mapping (IM) observations at the SKAO, focusing primarily on the sum of neutrino masses, Σmν . We forecast observations of the 21cm IM auto-power spectrum as well as the 21cm IM and galaxy surveys cross-correlation power spectrum. We construct different synthetic data sets of observations for the 21cm IM observables in the redshift range 0 < z < 3. For galaxy clustering, we consider two stage-IV surveys to mimic a DESI-like and Euclid-like cross-correlation signal.We study the impact of assuming three different fiducial values for the sum of neutrino masses, i.e. Σmν = 0.06, 0.1, 0.4 eV, in the synthetic data sets. To investigate the constraining power of the forecasted 21cm observations, we build a likelihood code that will be made publicly available upon publication. The results of the analysis, obtained through Markov Chain Monte Carlo techniques, are promising. We find that the 21cm auto-power spectrum alone could provide an upper limit on the sum of neutrino masses of Σmν < 0.287 eV, at 95% confidence level, for the case of the lowest fiducial value of Σmν . This result is comparable to the upper limits provided by cosmic microwave background (CMB) observations alone. When combining the 21cm auto-power spectrum synthetic data set with Planck 2018 CMB measurements, we find a tighter upper limit of Σmν < 0.105 eV, which improves on the constraints from Planck alone. We obtain a similar result already at the level of 21cm and galaxy clustering cross-correlation power spectrum, whose detection is more easily achieved as they are less affected by systematic effects. Combining synthetic data sets with Planck 2018 data, we find the upper limits of Σmν < 0.116 eV and Σmν < 0.117 eV for the 21cm signal in cross-correlation with the DESI-like and Euclid-like surveys, respectively. These constraints are comparable to those obtained by combining Planck data with the 21cm auto-power spectrum synthetic data sets, thus supporting the case for 21cm cross-correlation detections.

We present the discovery of a large-scale, limb-brightened outflow, extending at least 30 kpc above and below the star-forming disk of the edge-on galaxy ESO 130-G012 (D = 16.9 Mpc). Partially obscured by Galactic foreground stars and dust, this optically unremarkable, low-mass galaxy reveals one of the largest known hourglass-shaped outflows from the full extent of its bright stellar disk. The outflow was discovered in 944 MHz radio continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) obtained as part of the "Evolutionary Map of the Universe" (EMU) project. Its height is at least 3x that of the stellar disk diameter (~10 kpc), while its shape and size most resemble the large biconical, edge-brightened FUV and X-ray outflows in the nearby starburst galaxy NGC 3079. The large-scale, hourglass-shaped outflow of ESO 130-G012 appears to be hollow and originates from the star-forming disk, expanding into the halo with speeds close to the escape velocity before likely returning to the disk. Given ESO 130-G012's modest star formation rate, the height of the outflow is surprising and unusual, likely made possible by the galaxy's relatively low gravitational potential. Follow-up observations are expected to detect hot gas inside the bipolar outflow cones and magnetic fields along the X-shaped outflow wings. Neutral gas may also be lifted above the inner disk by the outflow.

We aim to characterize the nearby (23.78 pc), low-mass planetary system GJ,7 (TOI-198), which consists of an M0-type star and a terrestrial planet. Using photometric data from three sectors of the Transiting Exoplanet Survey Satellite TESS ) and a follow-up on the planetary transit observed by the Characterizing ExOPlanets Satellite ( CHEOPS ), along with 87 precise radial velocities obtained with the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph, we confidently confirm the planet and infer its properties. Planet GJ,7,b has a mass of M_p = 3.17 ^ +0.64 _ -0.65 M_⊕ and a radius of R_p = 1.36 ± 0.13 R_⊕. It orbits at a distance of a = 0.0675 ^ +0.0067 _ -0.0082 au from its host star with an orbital period of P = 10.215213 ^ +0.000011 _ -0.000010 d. We impose a 3σ upper limit on the planetary eccentricity of e łe 0.15. These parameters imply that GJ,7,b has a high density, ̊ho_p = 6.89 ^ +4.27 _ -2.78 g,cm -3 $, positioning it within the region of the rocky, Earth-like planets on the mass--radius diagram and interior to the inner edge of the habitable zone around its parent star. Additionally, we find that the host star is a slow rotator and is slightly metal-depleted ( Fe/H = -0.66 ± 0.10 dex), making GJ,7 one of the few planetary systems accurately characterized in the domain of subsolar iron abundances. TESS photometry does not show additional transit-like features attributable to planets with radii greater than ≈90,% that of Earth. The high number of radial velocity measurements enables us to determine that possible transiting and non-transiting planet candidates with masses lower than half the mass of GJ,7,b would have eluded detection in our in-depth study. The stellar activity, although moderate, shows a significant radial velocity amplitude of about 4 m,s$^ -1 and poses a challenge for detecting planets with masses lower than Earth around GJ,7.

We investigated how the obscured IR-derived and dust-corrected UV star formation rate functions (SFRFs) compare with each other and with predictions from state-of-the-art theoretical models of galaxy formation and evolution. We derived the IR SFRF from the ALMA A3COSMOS survey by converting the IR luminosity functions (IR LFs) into SFRFs after correcting for the active galactic nucleus (AGN) contribution. Similarly, we obtained the UV SFRFs from UV LFs in the literature, corrected for dust-extinction. First, we fit the two SFRFs independently via a Markov chain Monte Carlo (MCMC) approach, then we combined them to obtain the first estimate of the ``total'' SFRF out to z ∼ 6. Finally, we compared this SFRF with predictions of a set of theoretical models. We derive the UV and IR SFRFs at 0.5 &lt; z &lt; 6, using dust-extinction-corrected UV LFs from the literature and IR LFs from and ALMA. We find that the two functions are largely complementary, covering different ranges in star formation rate (SFR$ &lt; 10-100$ M_⊙yr-1 for the UV-corrected, and SFR &gt; 100$ M_⊙yr^-1 for the IR). From the comparison of the total SFRF with model predictions, we find overall good agreement at $z &lt; 2.5, with increasing difference at higher redshifts; all models miss the galaxies that form stars with the highest SFRs. Finally, we finally obtain the UV (dust-corrected), IR and total SFR densities (SFRDs), finding that there are no redshift ranges where UV and IR alone are able to reproduce the total SFRD. Herschel

Abstract We present ViSta , a Visibility Stacking method to combine interferometric observations in the Fourier domain at radio to sub-millimeter wavelengths for galaxies. The goal of our method is to maximize the exploitation of available archival interferometric data. By stacking visibilities of galaxies with secure spectroscopic redshifts directly in the Fourier domain and transforming them into the rest-frame, we can enhance the stacked signal, suppress noise, and improve image reconstruction thanks to an extended coverage of the visibility domain. The ViSta method is highly flexible, allowing stacking of visibilities regardless of the array configuration or spectral setup. It is effective for both targeted sources and spurious detections offset from the phase center, whether unresolved or extended, within the field of view of the telescope. We validated the method using simulated interferometric datasets. For point-like sources, we can reconstruct the true emission with approximately 90% accuracy, obtaining similar results to classical image-plane stacking. In contrast, for faint and extended sources below the noise level, our method can provide a more accurate estimate of the signal compared to traditional image-based approaches. Finally, we applied ViSta to a sample of dusty star-forming galaxies observed with the Atacama Large Millimeter/sub-millimeter Array to detect the CO(3–2) emission line. As for the simulated case, we demonstrated that our tool performs better than image-plane stacking when the signal from individual sources is no longer easily detectable, achieving higher SNR. Finally, we outline potential future applications of this stacking approach.