Luca Visinelli

Luca Visinelli
Shanghai Jiao Tong University | SJTU · Department of Physics

Ph.D. in physics
Associate professor, Shanghai Jiao Tong University

About

113
Publications
18,930
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Introduction
My research activity spans various interesting topics including particle astrophysics, dark matter, dark energy, and black holes. I have focused on exploring the role the axion as a dark matter candidate, for which I co-wrote a review on Physics Report in 2020. Recently, I have collaborated on an impactful review on the Hubble tension.
Additional affiliations
June 2015 - July 2016
University of Bologna
Position
  • Lecturer
January 2013 - July 2015
Centro Euro-Mediterraneo sui Cambiamenti Climatici
Position
  • Operational Global Carbon Observing System
August 2009 - May 2010
University of Utah
Position
  • The effect of dark matter on cosmic rays
Education
August 2007 - August 2011
University of Utah
Field of study
  • Physics
August 2007 - December 2011
University of Utah
Field of study
  • Physics

Publications

Publications (113)
Article
Full-text available
Axion miniclusters are dense bound structures of dark matter axions that are predicted to form in the postinflationary Peccei-Quinn symmetry breaking scenario. Although dense, miniclusters can easily be perturbed or even become unbound by interactions with baryonic objects such as stars. Here, we characterize the spatial distribution and properties...
Article
Full-text available
We review the landscape of QCD axion models. Theoretical constructions that extend the window for the axion mass and couplings beyond conventional regions are highlighted and classified. Bounds from cosmology, astrophysics and experimental searches are reexamined and updated.
Article
Full-text available
If the symmetry breaking leading to the origin of the axion dark matter field occurs after the end of inflation and is never restored, then overdensities in the axion field collapse to form dense objects known in the literature as axion miniclusters. The estimates of the typical minicluster mass and radius strongly depend on the details of the cosm...
Preprint
The Event Horizon Telescope (EHT) collaboration has recently released the first image of a black hole (BH), opening a new window onto tests of general relativity in the strong field regime. In this paper, we derive constraints on the nature of M87* (the supermassive object at the centre of the galaxy M87), exploiting the fact that its shadow appear...
Article
We constrain the coupling of thermally-produced axion-like particles (here axions) with photons and gluons, using data from the cosmic microwave background (CMB) spectra and baryon acoustic oscillations. The axion possesses an explicit soft breaking mass term and it is produced thermally in the early Universe from either axion-photon or axion-gluon...
Article
Full-text available
Dark matter annihilation might power the first luminous stars in the Universe. These types of stars, known as dark stars, could form in (106–108) M⊙ protohalos at redshifts z∼20, and they could be much more luminous and larger in size than ordinary stars powered by nuclear fusion. We investigate the formation of dark stars in the self-interacting d...
Preprint
Full-text available
We investigate the modifications in the neutrino flavor oscillations under the influence of a stochastic gravitational wave background (SGWB), in a scenario in which General Relativity is modified by an additional Chern-Simons (CS) term. Assuming that the dark matter halo is in the form of axions, the CS coupling modifies the pattern of the neutrin...
Article
Full-text available
Several recent works have tested fundamental physics with horizon-scale black hole (BH) images, using the size r sh and deviation from circularity Δ  of the BH shadow. For the Event Horizon Telescope image of Sgr A*, limits on Δ  are not available due to the sparse interferometric coverage of the 2017 observations, alongside the short variability...
Preprint
Full-text available
Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We consider a wide range of well-motivated deviations from classical General Relativity (GR) BH solutions, and constrain them using the Event Horizon Telescope (EHT) observations o...
Preprint
Ultra-light bosons can affect the dynamics of spinning black holes (BHs) via superradiant instability, which can lead to a time evolution of the supermassive BH shadow. We study prospects for witnessing the superradiance-induced BH shadow evolution, considering ultra-light scalar, vector, and tensor fields. We introduce two observables sensitive to...
Article
Full-text available
Ultralight bosons can affect the dynamics of spinning black holes (BHs) via superradiant instability, which can lead to a time evolution of the supermassive BH shadow. We study prospects for witnessing the superradiance-induced BH shadow evolution, considering ultralight vector and tensor fields. We introduce two observables sensitive to the shadow...
Preprint
We constrain the coupling of thermally-produced axion-like particles (here axions) with photons and gluons, using data from the cosmic microwave background (CMB) spectra and baryon acoustic oscillations. The axion possesses an explicit soft breaking mass term and it is produced thermally in the early Universe from either axion-photon or axion-gluon...
Article
Full-text available
The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good description of a wide range of astrophysical and cosmological data. However, there are a few big open questions that make the standard model look like an approximation to a more realistic scenario yet to be found. In this paper, we list a few important goals that need to be a...
Preprint
Full-text available
The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight ($<10\,$eV) bosonic dark matter...
Preprint
Full-text available
Axions are well-motivated dark matter candidates with simple cosmological production mechanisms. They were originally introduced to solve the strong CP problem, but also arise in a wide range of extensions to the Standard Model. This Snowmass white paper summarizes axion phenomenology and outlines next-generation laboratory experiments proposed to...
Preprint
Full-text available
It is widely accepted that the next lepton collider beyond a Higgs factory would require center-of-mass energy of the order of up to 15 TeV. Since, given reasonable space and cost restrictions, conventional accelerator technology reaches its limits near this energy, high-gradient advanced acceleration concepts are attractive. Advanced and novel acc...
Preprint
Full-text available
In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant $H_0$, the $\sigma_8$--$S_8$ tension, and other less statistically significant anomalies. While these...
Preprint
The $U(1)_{B\textrm{--}L}$ symmetry, the essential component in the seesaw mechanism and leptogenesis, is naturally equipped with a massive gauge boson. When the gauge coupling is of the order of $\mathcal{O}(10^{-19})$, this gauge boson is a light and long-lived dark matter candidate which dominantly decays into active neutrinos. This consistent d...
Article
Full-text available
Cosmic microwave background observations are used to constrain reheating to standard model (SM) particles after a period of inflation. As a light spectator field, the SM Higgs boson acquires large field values from its quantum fluctuations during inflation, gives masses to SM particles that vary from one Hubble patch to another, and thereby produce...
Preprint
Black hole (BH) shadows can be used to probe new physics in the form of ultra-light particles via the phenomenon of superradiant instability. By directly affecting the BH mass and spin, superradiance can lead to a time evolution of the BH shadow, which nonetheless has been argued to be unobservable through Very Long Baseline Interferometry (VLBI) o...
Article
Full-text available
Black hole (BH) shadows can be used to probe new physics in the form of ultra-light particles via the phenomenon of superradiant instability. By directly affecting the BH mass and spin, superradiance can lead to a time evolution of the BH shadow, which nonetheless has been argued to be unobservable through Very Long Baseline Interferometry (VLBI) o...
Article
Full-text available
Taking the recently reported nonzero rotation angle of the cosmic microwave background (CMB) linear polarization β=0.35±0.14 deg as the hint for a pseudo–Nambu-Goldstone boson quintessence dark energy (DE), we study the electroweak (EW) axion quintessence DE model where the axion mass is generated by the EW instantons. We find that the observed val...
Preprint
Full-text available
When the spontaneous breaking of the Peccei-Quinn (PQ) symmetry occurred, the resulting angular direction of the PQ field, i.e., the axion could have possessed an initial non-zero velocity arising from additional terms that explicitly break the PQ symmetry. This opens up the possibility for smaller values of the decay constant than in the conventio...
Article
Full-text available
The QCD axion is expected to form dense structures known as axion miniclusters if the Peccei-Quinn symmetry is broken after inflation. Miniclusters that have survived until today will interact with neutron stars (NSs) in the Milky Way to produce transient radio signals from axion-photon conversion in the NS magnetosphere. We quantify the properties...
Article
Full-text available
Compact objects occupy a pivotal role in the exploration of Nature. The interest spans from the role of compact objects in astrophysics to their detection through various methods (gravitational waves interferometry, microlensing, imaging). While the existence of compact objects made of fermions (neutron stars and white dwarfs) has been assessed, a...
Preprint
Full-text available
Compact objects occupy a pivotal role in the exploration of Nature. The interest spans from the role of compact objects in astrophysics to their detection through various methods (gravitational waves interferometry, microlensing, imaging). While the existence of compact objects made of fermions (neutron stars and white dwarfs) has been assessed, a...
Article
Full-text available
The simplest ΛCDM model provides a good fit to a large span of cosmological data but harbors large areas of phenomenology and ignorance. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the 4σ to 6σ disagreeme...
Article
We consider constraints on primordial black holes (PBHs) in the mass range (10−18–1015) M⊙ if the dark matter (DM) comprises weakly interacting massive particles (WIMPs) which form halos around them and generate γ-rays by annihilations. We first study the formation of the halos and find that their density profile prior to WIMP annihilations evolves...
Preprint
Full-text available
We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a...
Preprint
Taking the recently reported non-zero rotation angle of the cosmic microwave background (CMB) linear polarization $\beta=0.35\pm0.14{\rm\, deg}$ as the hint for a pseudo Nambu-Goldstone boson quintessence dark energy (DE), we study the electroweak (EW) axion quintessence DE model where the axion mass is generated by the EW instantons. We find that...
Article
Full-text available
The standard Λ Cold Dark Matter cosmological model provides an amazing description of a wide range of astrophysical and astronomical data. However, there are a few big open questions, that make the standard model look like a first-order approximation to a more realistic scenario that still needs to be fully understood. In this Letter of Interest we...
Article
Full-text available
The standard Λ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few statistically significant tensions and anomalies were found in the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physics bey...
Article
Full-text available
A precise measurement of the curvature of the Universe is of prime importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early-Universe scenarios. Recent observations, while broadly consistent with a spatially flat standard Λ Cold Dark Matter (ΛCDM) model, sho...
Article
Full-text available
The current cosmological probes have provided a fantastic confirmation of the standard Λ Cold Dark Matter cosmological model, which has been constrained with unprecedented accuracy. However, with the increase of the experimental sensitivity, a few statistically significant tensions between different independent cosmological datasets emerged. While...
Article
The first bright objects to form in the Universe might not have been ‘ordinary’ fusion-powered stars, but ‘dark stars’ (DSs) powered by the annihilation of dark matter (DM) in the form of weakly interacting massive particles (WIMPs). If discovered, DSs can provide a unique laboratory to test DM models. DSs are born with a mass of the order of M⊙ an...
Preprint
We explore the prospects for direct detection of dark energy by current and upcoming terrestrial dark matter direct detection experiments. If dark energy is driven by a new light degree of freedom coupled to matter and photons then dark energy quanta are predicted to be produced in the Sun. These quanta free-stream towards Earth where they can inte...
Article
Full-text available
We explore the prospects for direct detection of dark energy by current and upcoming terrestrial dark matter direct detection experiments. If dark energy is driven by a new light degree of freedom coupled to matter and photons then dark energy quanta are predicted to be produced in the Sun. These quanta free-stream toward Earth where they can inter...
Article
Full-text available
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has recently reported strong evidence for a stochastic process affecting the 12.5 yr dataset of pulsar timing residuals. We show that the signal can be interpreted in terms of a stochastic gravitational wave background emitted from a network of axionic strings...
Preprint
Full-text available
The $\Lambda$CDM model provides a good fit to a large span of cosmological data but harbors areas of phenomenology. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the $4-6\sigma$ disagreement between predict...
Preprint
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has recently reported strong evidence for a stochastic process affecting the 12.5 yr dataset of pulsar timing residuals. We show that the signal can be interpreted in terms of a stochastic gravitational wave background emitted from a network of axionic strings...
Article
Full-text available
We consider the observational constraints on stupendously large black holes (SLABs) in the mass range M ≳ 1011 M⊙. These have attracted little attention hitherto and we are aware of no published constraints on a SLAB population in the range (1012 – 1018) M⊙. However, there is already evidence for black holes of up to nearly 1011 M⊙ in galactic nucl...
Preprint
Full-text available
We propose a new way of studying the Higgs potential at extremely high energies. The SM Higgs boson, as a light spectator field during inflation in the early Universe, can acquire large field values from its quantum fluctuations which vary among different causal (Hubble) patches. Such a space dependence of the Higgs after the end of inflation leads...
Preprint
Axion miniclusters are dense bound structures of dark matter axions that are predicted to form in the post-inflationary Peccei-Quinn symmetry breaking scenario. Although dense, miniclusters can easily be perturbed or even become unbound by interactions with baryonic objects such as stars. Here, we characterize the spatial distribution and propertie...
Preprint
The QCD axion is expected to form dense structures known as axion miniclusters if the Peccei-Quinn symmetry is broken after inflation. Miniclusters that have survived until today would interact with the population of neutron stars (NSs) in the Milky Way to produce transient radio signals from axion-photon conversion in the NS magnetosphere. Here, w...
Preprint
We consider constraints on primordial black holes (PBHs) in the mass range $( 10^{-18}$ - $10^{15} )\,M_{\odot}$ if the dark matter (DM) comprises weakly interacting massive particles (WIMPs) which form halos around them and generate $\gamma$-rays by annihilations. The observed extragalactic $\gamma$-ray background then implies that the PBH DM frac...
Preprint
The first bright objects to form in the Universe might not have been "ordinary" fusion-powered stars, but "Dark Stars" (DSs) powered by the annihilation of dark matter (DM) in the form of Weakly Interacting Massive Particles (WIMPs). If discovered, DSs can provide a unique laboratory to test DM models. DSs are born with a mass of order $M_\odot$ an...
Preprint
Full-text available
Cosmic Microwave Background (CMB) observations are used to constrain reheating to Standard Model (SM) particles after a period of inflation. As a light spectator field, the SM Higgs boson acquires large field values from its quantum fluctuations during inflation, gives masses to SM particles that vary from one Hubble patch to another, and thereby p...
Preprint
Full-text available
The standard $\Lambda$ Cold Dark Matter cosmological model provides an amazing description of a wide range of astrophysical and astronomical data. However, there are a few big open questions, that make the standard model look like a first-order approximation to a more realistic scenario that still needs to be fully understood. In this Letter of Int...
Preprint
Full-text available
A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios. The recent observations, while broadly consistent with a spatially flat standard $\Lambda$ Cold Dark Matter ($...
Preprint
Full-text available
The standard $\Lambda$ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few tensions and anomalies became statistically significant with the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physi...
Preprint
Full-text available
The current cosmological probes have provided a fantastic confirmation of the standard $\Lambda$ Cold Dark Matter cosmological model, that has been constrained with unprecedented accuracy. However, with the increase of the experimental sensitivity a few statistically significant tensions between different independent cosmological datasets emerged....
Preprint
We consider the observational constraints on stupendously large black holes (SLABs) in the mass range $M \gtrsim 10^{11}\,M_{\odot}$. These have attracted little attention hitherto and we are aware of no published constraints on a SLAB population in the range $(10^{12}$ - $10^{18})\,M_{\odot}$. However, there is already evidence for black holes of...
Article
Full-text available
Recently, Tsupko et al. have put forward the very interesting proposal to use the shadows of high-redshift supermassive black holes (SMBHs) as standard rulers. This would in principle allow us to probe the expansion history within a redshift range which would otherwise be challenging to access. In this note, we critically examine this proposal, and...
Preprint
Full-text available
We review the landscape of QCD axion models. Theoretical constructions that extend the window for the axion mass and couplings beyond conventional regions are highlighted and classified. Bounds from cosmology, astrophysics and experimental searches are reexamined and updated.
Preprint
Full-text available
Recently, Tsupko et al. have put forward the very interesting proposal to use the shadows of high-redshift supermassive black holes (SMBHs) as standard rulers. This would in principle allow us to probe the expansion history within a redshift range which would otherwise be challenging to access. In this short note, we critically examine this proposa...
Preprint
We consider the possibility that dark energy and baryons might scatter off each other. The type of interaction we consider leads to a pure momentum exchange, and does not affect the background evolution of the expansion history. We parametrize this interaction in an effective way at the level of Boltzmann equations. We compute the effect of dark en...
Article
Full-text available
We consider the possibility that dark energy and baryons might scatter off each other. The type of interaction we consider leads to a pure momentum exchange, and does not affect the background evolution of the expansion history. We parametrize this interaction in an effective way at the level of Boltzmann equations. We compute the effect of dark en...
Preprint
Full-text available
The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals that started a real race towards their discovery. This paper is the Conceptual Design Report of the KLASH (KLoe magnet for Axion SearcH) experiment at the Laboratori Nazionali di Frascati (LNF...
Article
Full-text available
We consider a quintessence field which transitions from a matter-like to a cosmological constant behaviour between recombination and the present time. We aim at easing the tension in the measurement of the present Hubble rate, and we assess the ΛCDM model properly enlarged to include our quintessence field against cosmological observations. The mod...
Preprint
Full-text available
Persisting tensions between high-redshift and low-redshift precision cosmological observations suggest the dark energy sector of the Universe might be more complex than the positive cosmological constant of the $\Lambda$CDM model, and in particular might have a negative energy density. Motivated by string theory considerations, wherein consistent A...
Article
Full-text available
Persisting tensions between high-redshift and low-redshift cosmological observations suggest the dark energy sector of the Universe might be more complex than the positive cosmological constant of the Λ CDM model. Motivated by string theory, wherein symmetry considerations make consistent AdS backgrounds (i.e., maximally-symmetric spacetimes with a...
Preprint
In order to accommodate the QCD axion as the dark matter (DM) in a model in which the Peccei-Quinn (PQ) symmetry is broken before the end of inflation, a relatively low scale of inflation has to be invoked in order to avoid bounds from DM isocurvature fluctuations. We construct a simple model in which the Standard Model Higgs field is non-minimally...