A5025437330- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Statistical and numerical algorithms
- Geophysics and Gravity Measurements
- Black Holes and Theoretical Physics
- History and Developments in Astronomy
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Planetary Science and Exploration
- Mechanics and Biomechanics Studies
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Statistics Education and Methodologies
- Solar and Space Plasma Dynamics
Scuola Superiore Meridionale
2021-2025
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2025
Istituto Nazionale di Fisica Nucleare
2024-2025
Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
2022-2024
University of Florence
2020
Emerging high-redshift cosmological probes, in particular quasars (QSOs), show a preference for larger matter densities, ${\mathrm{\ensuremath{\Omega}}}_{m}\ensuremath{\approx}1$, within the flat $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ framework. Here, using Risaliti-Lusso relation standardizable QSOs, we demonstrate that QSOs recover same Planck-$\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ universe as type Ia supernovae (SN), ${\mathrm{\ensuremath{\Omega}}}_{m}\ensuremath{\approx}0.3$ at...
The recent $\sim 4 \, \sigma$ Hubble constant, $H_{0}$, tension is observed between the value of $H_{0}$ from Cosmic Microwave Background (CMB) and Type Ia Supernovae (SNe Ia). It a decade since this excruciating modern astrophysical community. To shed light on problem key to consider probes at intermediate redshifts SNe CMB reduce uncertainty $H_0$. Toward these goals, we fill redshift gap by employing Gamma-Ray Bursts (GRBs) Quasars (QSOs), reaching $z=9.4$ $z=7.6$, respectively, combined...
We present a new catalogue of ∼2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM–Newton . The sample can be used to investigate the non-linear relation between ultraviolet (UV) luminosity as well build Hubble diagram up redshift z ∼ 7.5. sources that are neither reddened by dust in optical UV nor obscured gas X-rays, whose fluxes free flux-limit-related biases. After checking for any possible systematics, we confirm, agreement our...
ABSTRACT Gamma-ray bursts (GRBs), can be employed as standardized candles, extending the distance ladder beyond Type Ia supernovae (SNe Ia, z = 2.26). We standardize GRBs using three-dimensional (3D) Fundamental Plane relation (the Dainotti relation) among rest-frame end time of X-ray plateau emission, its corresponding luminosity, and peak prompt luminosity. Combining SNe GRBs, we constrain ΩM 0.299 ± 0.009 assuming a flat Λ cold dark matter (ΛCDM) cosmology with without correcting for...
ABSTRACT We analyse some open debates in cosmology light of the most updated quasar (QSO) sample, covering a wide redshift range up to $\mathit{ z}$ ∼ 7.5, combined with type Ia supernovae (SNe) and baryon acoustic oscillations (BAOs). Indeed, extending cosmological analyses high-redshift data is key distinguishing between different models that are degenerate at low redshifts, allowing better constraints on possible dark energy (DE) evolution. Also, we discuss combinations BAO, SNe, QSO...
Abstract Quasars (QSOs) are extremely luminous active galactic nuclei currently observed up to redshift z = 7.642. As such, they have the potential be next rung of cosmic distance ladder beyond Type Ia supernovae, if can reliably used as cosmological probes. The main issue in adopting QSOs standard candles (similarly gamma-ray bursts) is large intrinsic scatter relations between their properties. This could overcome by finding correlations among observables that physics and not artifacts...
Abstract Cosmological models and their parameters are widely debated because of theoretical observational mismatches the standard cosmological model, especially current discrepancy between value Hubble constant, H 0 , obtained by Type Ia supernovae (SNe Ia), cosmic microwave background radiation (CMB). Thus, considering high-redshift probes like quasars (QSOs), having intermediate redshifts SNe CMB, is a necessary step. In this work, we use most updated QSO sample, reaching up to z ∼ 7.5,...
Abstract Cosmological models and their parameters are widely debated, especially about whether the current discrepancy between values of Hubble constant, H 0 , obtained by Type Ia supernovae (SNe Ia) Planck data from cosmic microwave background radiation could be alleviated when alternative cosmological considered. Thus, combining high-redshift probes, such as gamma-ray bursts (GRBs) quasi-stellar objects (QSOs, or quasars), together with baryon acoustic oscillations SNe is important to...
The longstanding search for the cosmological model that best describes Universe has been made more intriguing since recent discovery of Hubble constant, $H_{0}$, tension observed between value $H_{0}$ from Cosmic Microwave Background and type Ia supernovae (SNe Ia). Hence, commonly trusted flat $\Lambda$CDM is under investigation. In this scenario, cosmography a very powerful technique to investigate evolution without any assumption, thus revealing tensions observational data predictions...
Cosmography is a powerful tool to investigate the Universe kinematic and then reconstruct dynamics in model-independent way. However, recent new measurements of supernovae Ia quasars have populated Hubble diagram up high redshifts ($z \sim 7.5$) application traditional cosmographic approach has become less straightforward due large implied. Here we this issue through an expansion luminosity distance-redshift relation terms "orthogonal" logarithmic polynomials. In particular point out...
Abstract Currently, the Λ cold dark matter model, which relies on existence of and a cosmological constant Λ, best describes universe. However, we lack information in high-redshift ( z ) region between Type Ia supernovae (SNe Ia; up to = 2.26) cosmic microwave background 1100), an interval crucial test models their possible evolution. We have defined sample 983 quasars 7.54 with reduced intrinsic dispersion δ 0.007, determines density parameter Ω M same precision SNe Ia. Although previous...
Although the Λ Cold Dark Matter model is most accredited cosmological model, information at high redshifts (z) between type Ia supernovae (z=2.26) and Cosmic Microwave Background (z=1100) crucial to validate this further. To end, we have discovered a sample of 1132 quasars up z=7.54 exhibiting reduced intrinsic dispersion relation ultraviolet X-ray fluxes, δF=0.22 vs. δF=0.29 (24% less), than original sample. This gold sample, once correct luminosities for selection biases redshift...
Since 1969, 55 years ago, Lunar Laser Ranging (LLR) has provided accurate and precise (down to ~1 cm RMS) measurements of the Moon’s orbit thanks Apollo Lunokhod Cube Corner Retroreflector (CCR) Arrays (LRAs) deployed on Moon. Nowadays, current level precision these is largely limited by lunar librations affecting old generation LRAs. To improve this situation, next-generation libration-free retroreflectors are necessary. end, Satellite/lunar/GNSS laser ranging/altimetry cube/microsat...
Type Ia Supernovae (SNe Ia) are considered the most reliable \textit{standard candles} and they have played an invaluable role in cosmology since discovery of Universe's accelerated expansion. During last decades, SNe samples been improved number, redshift coverage, calibration methodology, systematics treatment. These efforts led to recent \textit{``Pantheon"} (2018) \textit{``Pantheon +"} (2022) releases, which enable constrain cosmological parameters more precisely than previous samples....
Context. A non-linear relation between quasar monochromatic luminosities at 2500 Å and 2 keV holds all observed redshifts luminosities, it has been used to derive distances build a Hubble diagram of quasars. The choice the X-ray UV indicators so far somewhat arbitrary typically relied on photometric data. Aims. We aim determine proxies that provide smallest dispersion in order obtain more precise distance estimates confirm reliability X-ray-to-UV as indicator. Methods. performed complete...
We present the analysis of rest frame ultraviolet and optical spectra 30 bright blue quasars at z ∼ 3, selected to examine suitability active galactic nuclei as cosmological probes. In our previous works, based on pointed XMM-Newton observations, we found an unexpectedly high fraction (≈25%) X-ray weak in sample. The latter sources also display a flatter UV continuum broader fainter C IV profile archival data with respect their normal counterparts. Here new observations Large Binocular...
We analyse the properties of CIV broad emission line in connection with X-ray 30 bright SDSS quasars at z~3.0-3.3 pointed XMM-Newton observations, which were selected to test suitability AGN as cosmological tools. In our previous work, we found that a large fraction (~25%) this sample are underluminous by factors >3-10. As absorbing columns >10$^{23}$ cm$^{-2}$ can be safely ruled out, their weakness is most likely intrinsic. Here explore possible correlations between UV and features these...
In the past few years, we built a Hubble diagram of quasars up to redshift z$\sim$7, based on nonlinear relation between quasars' x-ray and UV luminosities. Such shows >4$\sigma$ deviation from standard flat $\Lambda$CDM model at z>1.5. Given important consequences this result, it is fundamental rule out any systematic effect in selection sample and/or flux measurements, investigate possible dependences relation, that would invalidate use as candles. Here review all observational results...
We present the analysis of rest frame ultraviolet and optical spectra 30 bright blue quasars at $z\sim3$, selected to examine suitability AGN as cosmological probes. In our previous works, we found an unexpectedly high fraction ($\approx 25 \%$) X-ray weak in sample. The latter sources also display a flatter UV continuum broader fainter CIV profile archival data with respect their normal counterparts. Here new observations LBT both $zJ$ (rest-frame $\simeq$2300-3100 $\rm \mathring{A}$) $K_S$...
Cosmological models and their parameters are widely debated, especially about whether the current discrepancy between values of Hubble constant, $H_{0}$, obtained by type Ia supernovae (SNe Ia), Planck data from Cosmic Microwave Background Radiation could be alleviated when alternative cosmological considered. Thus, combining high-redshift probes, such as Gamma-Ray Bursts (GRBs) Quasars (QSOs), together with Baryon Acoustic Oscillations (BAO) SNe is important to assess viability these if...
Cosmological models and their parameters are widely debated because of theoretical observational mismatches the standard cosmological model, especially current discrepancy between value Hubble constant, $H_{0}$, obtained by Type Ia supernovae (SNe Ia), Cosmic Microwave Background Radiation (CMB). Thus, considering high-redshift probes like quasars (QSOs), having intermediate redshifts SNe CMB, is a necessary step. In this work, we use most updated QSO sample, reaching up to $z\sim7.5$,...
Although the $\Lambda$ Cold Dark Matter model is most accredited cosmological model, information at high redshifts ($z$) between type Ia supernovae ($z=2.26$) and Cosmic Microwave Background ($z=1100$) crucial to validate this further. To end, we have discovered a sample of 1132 quasars up $z=7.54$ exhibiting reduced intrinsic dispersion relation ultraviolet X-ray fluxes, $\delta_\mathrm{F}=0.22$ vs. $\delta_\mathrm{F}=0.29$ ($24\%$ less), than original sample. This gold sample, once correct...