arXiv subjects

Fabrizio Arrigoni-Battaia

Publications and source records attributed to Fabrizio Arrigoni-Battaia.

9 recordsLinked to original sources

arXiv2026

$\textit{Nāpōwawā`enakaulua}$: a close quasar pair at cosmic dawn in the Aether survey

We present the discovery and first characterization of $\textit{Nāpōwawā`enakaulua}$: the most compact known quasar pair candidate in the Epoch of Reionization, with a projected separation of only $0.98^{\prime\prime}$ ($\approx 5.56$ pkpc at $z \sim 6.08$) and a velocity offset of $Δv \simeq 15 \text{ km s}^{-1}$. Using spectroscopy from JWST/NIRSpec IFU, as part of the $\textit{Aether survey}$, Gemini/GNIRS and GMOS we characterize the continuum and emission line properties of the two quasars, enabling constraints on their black hole masses ($M_{\text{BH}} \simeq 1.5 \times 10^9$ and $4.0 \times 10^8\,M_\odot$), accretion states ($λ_{\text{Edd}} \simeq 1.23$ and $1.07$), and systemic redshifts ($z_{\rm sys} \simeq 6.0781$ and $6.0785$). We place this pair in the cosmological context by comparing the chance of occurrence to extrapolations of high-$z$ quasar clustering measurements at larger scales, resulting in a $\sim 2-3$ order of magnitude excess with respect to expectations. This excess hints at an underlying population of merger-triggered quasar pairs at cosmic dawn or to a denser-than-average galactic environment. $\textit{Nāpōwawā`enakaulua}$ thus represents a crucial signpost to investigate the mass assembly of the first massive galaxies and black holes.

astro-ph.GA↗

arXiv2026

The birth of the intracluster medium: the evolution of multiphase gas and Lyman-$α$ haloes in a simulated $z\sim3$ protocluster

Galactic haloes host a complex, multiphase circumgalactic medium (CGM), and at high redshift are fed by cold, filamentary inflows. In contrast, mature galaxy clusters are dominated by a hot, enriched, X-ray emitting intracluster medium (ICM), with cold gas largely confined to member galaxies. However, the transition between these regimes remains poorly constrained. We present a cosmological zoom-in simulation of a massive cluster progenitor evolved to $z=2.7$, with enhanced CGM resolution to better trace the accretion, mergers and feedback events that precede the birth of the ICM. We connect this evolution to mock MgII, CII, OVI and OVII absorption, tracing low and high ionisation gas phases. We also study Lyman-$α$ (Ly$α$) and Balmer-$α$ (H$α$) haloes in emission, using radiative transfer in post-processing. Between $z\sim4.4$ and $2.7$, a major merger and AGN feedback drive an inside-out transformation, redistributing gas to larger radii and flattening density, temperature and metallicity profiles. Intermediate column MgII absorbers are rapidly destroyed, leaving a clumpier cold gas distribution associated with satellites, while gas is ionised beyond OVII as the inner halo enters the X-ray regime. An extended Ly$α$ halo remains detectable even without AGN photoionisation, and evolves from filamentary to more spherical as inflowing gas is disrupted. Our fiducial model underpredicts observed central Ly$α$ emission - we likely require more efficient Ly$α$ production in the nuclear region, either through more effective escape of stellar Ly$α$ photons or through enhanced conversion of AGN-powered ionisation into Ly$α$ emission. H$α$ haloes are dimmer and smaller than Ly$α$, but with JWST may provide a complementary probe of the evolving CGM at this critical epoch.

astro-ph.GA↗

arXiv2026

The imprint of AGN-driven outflows on the CGM: the case of Lyα nebulae around high-z quasars

Some cosmological hydrodynamical simulations predict that outflows driven by active galactic nuclei (AGN) play a key role in powering the Ly$α$ nebulae observed around high-redshift quasars. In such simulations, AGN feedback seeded as powerful outflows leads to extended and luminous nebulae whose morphology and surface-brightness profiles accurately reproduce the observations, while suppressing AGN feedback leads to compact and faint nebulae. This link might arise from outflows opening up a channel for Ly$α$ photons to escape from the galactic nucleus to the circumgalactic medium (CGM). The main aim of this paper is to test this theoretical prediction using observations, by comparing the physical properties of outflows and Ly$α$ nebulae. We analyze integral-field unit data obtained with VLT/ERIS and GEMINI/GNIRS to trace the ionized gas in the interstellar medium (ISM) of a sample of six quasars at $z\sim2-3$, using the [O III] emission line. We detect powerful outflows in all the quasars of our sample, with velocities $>1500~\mathrm{km~s^{-1}}$ and kinetic energies $ \gtrsim 2\times10^{43}~\mathrm{erg~s^{-1}}$. Four of our quasars are spatially resolved and show signs of extended [O III] emission out to distances $>2$ kpc from the central supermassive black hole. When excluding one outlier, we find a positive monotonic correlation between the outflow power and the Ly$α$ nebulae size ($ρ=0.89$, $p=0.03$) and luminosity ($ρ=0.6$, $p=0.28$). Additionally, we find evidence of spatial alignment between the ionization cone and the inner and brightest regions of the Ly$α$ nebula. Our results provide tentative evidence in support of the theoretical prediction that AGN-driven outflows at ISM scales open a low-optical-depth path for central Ly$α$ photons to reach the CGM and create extended nebulae.

astro-ph.GA↗

arXiv2021

ALMA reveals large overdensity and strong clustering of galaxies in quasar environments at $z\sim4$

We present an Atacama Large Millimeter/submillimeter Array (ALMA) survey of CO(4--3) line emitting galaxies in 17 quasar fields at $z\sim4$ aimed to perform the first systematic search of dusty galaxies in high$-z$ quasar environments. Our blind search of galaxies around the quasars results in 5 CO emitters with S/N$\geq5.6$ within a projected radius of $R\lesssim1.5\,h^{-1}\,$cMpc and a velocity range of $\rmΔ\,v=\pm1000\,$km\,s$^{-1}$ around the quasar. In blank fields, we expect to detect only 0.28 CO emitters within the same volume, implying a total overdensity of $17.6^{+11.9}_{-7.6}$ in our fields, and indicating that quasars trace massive structures in the early universe. We quantify this overdensity by measuring the small-scale clustering of CO emitters around quasars, resulting in a cross-correlation length of $r_{\rm 0,QG}=8.37^{+2.42}_{-2.04}\,h^{-1}\,$cMpc, assuming a fixed slope $γ=1.8$. This contradicts the reported mild overdensities (x1.4) of Lyman alpha emitters (LAEs) in the same fields at scales of $R\lesssim7\,h^{-1}\,$cMpc which is well described by a cross-correlation length 3 times lower than that measured for CO emitters. We discuss some possibilities to explain this discrepancy, including low star formation efficiency, and excess of dust in galaxies around quasars. Finally, we constrain, for the first time, the clustering of CO emitters at $z\sim4$, finding an auto-correlation length of $r_{\rm 0,CO}=3.14\pm1.71\,h^{-1}\,$cMpc (with $γ=1.8$). Our work together with the previous study of LAEs around quasars traces simultaneously the clustering properties of both optical and dusty galaxy populations in quasars fields, stressing the importance of multi-wavelength studies, and highlighting important questions about galaxy properties in high$-z$ dense environments.

astro-ph.GA↗

arXiv2020

A search for dust and molecular gas in enormous Ly$α$ nebulae at $z\approx 2$

Enormous Ly$α$ nebulae, extending over 300-500\,kpc around quasars, represent the pinnacle of galaxy and cluster formation. Here we present IRAM Plateau de Bure Interferometer observations of the enormous Ly$α$ nebulae `Slug' ($z$=$2.282$) and `Jackpot' ($z$=$2.041$). Our data reveal bright, synchrotron emission associated with the two radio-loud AGN embedded in the targeted nebulae, as well as molecular gas, as traced via the CO(3-2) line, in three galaxies (two sources in the Slug, and one in the Jackpot). All of the CO emission is associated with galaxies detected in their rest-frame UV stellar emission. The total mass in molecular gas of these three galaxies [$\sim (3-5)\times10^{10}$ M$_\odot$] is comparable with the total ionized gas mass responsible for the diffuse nebular emission. Our observations place limits on the molecular gas emission in the nebulae: The molecular gas surface density is $Σ_{\rm H2}<12-25$ M$_\odot$ pc$^{-2}$ for the Slug nebula and $Σ_{\rm H2}<34-68$ M$_\odot$ pc$^{-2}$ for the Jackpot nebula. These are consistent with the expected molecular gas surface densities, as predicted via photoionization models of the rest-frame UV line emission in the nebulae, and via Ly$α$ absorption in the Jackpot nebula. Compared to other radio--loud quasars at $z>1$, and high-redshift radio--loud galaxies, we do not find any strong trends relating the molecular gas reservoirs, the radio power, and the Ly$α$ luminosities of these systems. The significant step in sensitivity required to achieve a detection of the molecular gas from the nebulae, if present, will require a substantial time investment with JVLA, NOEMA, or ALMA.

astro-ph.GA↗

arXiv2019

The REQUIEM Survey I: A Search for Extended Ly-Alpha Nebular Emission Around 31 z>5.7 Quasars

The discovery of quasars few hundred megayears after the Big Bang represents a major challenge to our understanding of black holes and galaxy formation and evolution. Their luminosity is produced by extreme gas accretion onto black holes, which already reached masses of 10$^9$ M$_\odot$ by z ~ 6. Simultaneously, their host galaxies form hundreds of stars per year, using up gas in the process. To understand which environments are able to sustain the rapid formation of these extreme sources we started a VLT/MUSE effort aimed at characterizing the surroundings of a sample of 5.7 < z < 6.6 quasars dubbed: the Reionization Epoch QUasar InvEstigation with MUSE (REQUIEM) survey. We here present results of our searches for extended Ly-Alpha halos around the first 31 targets observed as part of this program. Reaching 5-sigma surface brightness limits of 0.1-1.1 x 10$^{-17}$ erg/s/cm$^2$/arcsec$^2$ over a 1 arcsec$^2$ aperture, we were able to unveil the presence of 12 Ly-Alpha nebulae, 8 of which are newly discovered. The detected nebulae show a variety of emission properties and morphologies with luminosities ranging from 8 x 10$^{42}$ to 2 x 10$^{44}$ erg/s, FWHMs between 300 and 1700 km/s, sizes < 30 pkpc, and redshifts consistent with those of the quasar host galaxies. As the first statistical and homogeneous investigation of the circum-galactic medium of massive galaxies at the end of the reionization epoch, the REQUIEM survey enables the study of the evolution of the cool gas surrounding quasars in the first 3 Gyr of the Universe. A comparison with the extended Ly-Alpha emission observed around bright (M$_{1450}$ < -25 mag) quasars at intermediate redshift indicates little variations on the properties of the cool gas from z ~ 6 to z ~ 3 followed by a decline in the average surface brightness down to z ~ 2.

astro-ph.GA↗

arXiv2017

Mapping the Lyman-Alpha Emission Around a z~6.6 QSO with MUSE: Extended Emission and a Companion at Close Separation

We utilize the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) to search for extended Lyman-Alpha emission around the z~6.6 QSO J0305-3150. After carefully subtracting the point-spread-function, we reach a nominal 5-sigma surface brightness limit of SB = 1.9x10$^{-18}$ erg/s/cm$^2$/arcsec$^2$ over a 1 arcsec$^2$ aperture, collapsing 5 wavelength slices centered at the expected location of the redshifted Lyman-Alpha emission (i.e. at 9256 Ang.). Current data suggest the presence (5-sigma, accounting for systematics) of a Lyman-Alpha nebula that extends for 9 kpc around the QSO. This emission is displaced and redshifted by 155 km/s with respect to the location of the QSO host galaxy traced by the [CII] emission line. The total luminosity is L = 3.0x10$^{42}$ erg/s. Our analysis suggests that this emission is unlikely to rise from optically thick clouds illuminated by the ionizing radiation of the QSO. It is more plausible that the Lyman-Alpha emission is due to fluorescence of the highly ionized optically thin gas. This scenario implies a high hydrogen volume density of n$_H$ ~ 6 cm$^{-3}$. In addition, we detect a Lyman-Alpha emitter (LAE) in the immediate vicinity of the QSO: i.e., with a projected separation of 12.5 kpc and a line-of-sight velocity difference of 560 km/s. The luminosity of the LAE is L = 2.1x10$^{42}$ erg/s and its inferred star-formation-rate is SFR ~ 1.3 M$_\odot$/yr. The probability of finding such a close LAE is one order of magnitude above the expectations based on the QSO-galaxy cross-correlation function. This discovery is in agreement with a scenario where dissipative interactions favour the rapid build-up of super-massive black holes at early Cosmic times.

astro-ph.GA↗

arXiv2015

Quasar Quartet Embedded in Giant Nebula Reveals Rare Massive Structure in Distant Universe

All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-alpha emission at redshift z ~ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ~10^-7, implying a physical connection between Lyman-alpha nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (~ 10^11 solar masses) of cool dense (volume density ~1 cm^-3) gas, which is in conflict with current cosmological simulations.

astro-ph.GA↗

arXiv2014

A cosmic web filament revealed in Lyman-alpha emission around a luminous high-redshift quasar

Simulations of structure formation in the Universe predict that galaxies are embedded in a "cosmic web", where the majority of baryons reside as rarefied and highly ionized gas. This material has been studied for decades in absorption against background sources, but the sparseness of these inherently one-dimensional probes preclude direct constraints on the three-dimensional morphology of the underlying web. Here we report observations of a cosmic web filament in Lyman-alpha emission, discovered during a survey for cosmic gas fluorescently "illuminated" by bright quasars at z=2.3. With a projected size of approximately 460 physical kpc, the Lyman-alpha emission surrounding the radio-quiet quasar UM287 extends well beyond the virial radius of any plausible associated dark matter halo. The estimated cold gas mass of the nebula from the observed emission is at least ten times larger than what is typically found by cosmological simulations, suggesting that a population of intergalactic gas clumps with sub-kpc sizes may be missing within current numerical models.

astro-ph.CO↗