A5000818951- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Black Holes and Theoretical Physics
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Reproductive Health and Technologies
- Stochastic processes and financial applications
- Relativity and Gravitational Theory
- Computational Physics and Python Applications
- Urban, Neighborhood, and Segregation Studies
- Stochastic processes and statistical mechanics
- Neutrino Physics Research
- Quantum Information and Cryptography
- Quantum Chromodynamics and Particle Interactions
- Medical History and Research
- Historical Studies on Reproduction, Gender, Health, and Societal Changes
- Advanced Thermodynamics and Statistical Mechanics
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Diverse Historical and Scientific Studies
- Gender Roles and Identity Studies
Stockholm University
2019-2024
AlbaNova
2021-2024
Institute for High Energy Physics
2022
University of Cambridge
2016-2018
University of Oxford
2013-2016
Osservatorio astronomico di Bologna
2014
University of Bologna
2014
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna
2014
The Abdus Salam International Centre for Theoretical Physics (ICTP)
2014
Axions/axion-like particles (ALPs) are a well motivated extension of the Standard Model and generic within String Theory. The X-ray transparency intracluster medium (ICM) in galaxy clusters is powerful probe light ALPs (with mass $<10^{-11}\,{\rm eV}$); as photons from an embedded or background source propagate through magnetized ICM, they may undergo energy-dependent quantum mechanical conversion into (and vice versa), imprinting distortions on spectrum. We present Chandra data for active...
We review the physics potential of a next generation search for solar axions: International Axion Observatory (IAXO) . Endowed with sensitivity to discover axion-like particles (ALPs) coupling photons as small gaγ∼ 10−12 GeV−1, or electrons gae∼10−13, IAXO has find QCD axion in 1 meV∼1 eV mass range where it solves strong CP problem, can account cold dark matter Universe and be responsible anomalous cooling observed number stellar systems. At same time, will have enough detect lower axions...
Axion-Like Particles (ALPs) are predicted by several Beyond the Standard Model theories, in particular, string theory. In presence of an external magnetic field perpendicular to direction propagation, ALPs can couple photons. Therefore, if X-ray source is viewed through a magnetised plasma, such as luminous quasar galaxy cluster, we may expect spectral distortions that well described photon-ALP oscillations. We present $571 \ \mathrm{ks}$ combined High and Low Energy Transmission Grating...
We investigate the characteristics of gamma-ray signal following decay MeV-scale Axion-Like Particles (ALPs) coupled to photons which are produced in a Supernova (SN) explosion. This analysis is first include production heavier ALPs through photon coalescence process, enlarging mass range that could be observed this way and giving stronger bound from observation SN 1987A. Furthermore, we present new analytical method for calculating predicted ALP decays. With can rigorously prove validity an...
Gravitationally bound clumps of dark matter axions in the form ``miniclusters'' or even denser ``axion stars'' can generate strong radio signals through axion-photon conversion when encountering highly magnetized neutron star magnetospheres. We systematically study encounters axion with stars and characterize infall, subsequent propagation photons. show that high density low escape velocity lead to strong, narrow, temporally characteristic transient lines an expected duration varying from...
Galaxy clusters can efficiently convert axion-like particles (ALPs) to photons. We propose that the recently claimed detection of a 3.55--3.57 keV line in stacked spectra large number galaxy and Andromeda may originate from decay either scalar or fermionic $7.1$ dark matter species into an particle (ALP) mass $m_{a} \lesssim 6\cdot 10^{-11}~{\rm eV}$, which subsequently converts photon cluster magnetic field. In contrast models arises directly annihilation, this explain anomalous strength...
Primordial decays of string theory moduli at $z\ensuremath{\sim}{10}^{12}$ naturally generate a dark radiation cosmic axion background with 0.1--1 keV energies. This can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses the extreme ultraviolet and soft x-ray bands. Substantial observable luminosities may generated even for couplings $\ensuremath{\ll}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$. We propose...
It has recently been conjectured that string theory does not admit de Sitter vacua, and quintessence explains the current epoch of accelerated cosmic expansion. A proposed, key prediction this scenario is time-varying couplings in dark sector, induced by evolving field. We note cosmological models with varying suffer from severe problems quantum corrections, beyond those shared all models. The vacuum energy depends on masses theory, even small variations parameters can lead to overwhelmingly...
A bstract In negatively curved field spaces, inflation can be realised even in steep potentials. Hyperinflation invokes the ‘centrifugal force’ of a orbiting hyperbolic plane to sustain inflation. We generalise hyperinflation by showing that it models with any number fields ( N f ≥ 2), and broad classes potentials that, particular, don’t need rotationally symmetric. For example, follow period radial slow-roll undergoes geometric destabilisation, yet this inflationary phase is not identical...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Abstract We show that in theories of axionlike particles (ALPs) coupled to electrons at tree-level, the one-loop effective coupling photons is process dependent: relevant for decay processes, g aγ (D) , differs significantly from appearing phenomenologically important Primakoff process, (P) . this has implications physics massive ALPs hot and dense environments, such as supernovae. derive, a consequence, new limits on ALP-electron coupling, ĝ ae SN 1987A by accounting all production...
Axion-like particles (ALPs) and photons can quantum mechanically interconvert when propagating through magnetic fields, ALP-photon conversion may induce oscillatory features in the spectra of astrophysical sources. We use deep (370 ks), short frame time Chandra observations bright nucleus at centre radio galaxy M87 Virgo cluster to search for signatures light ALPs. The absence substantial irregularities X-ray power-law spectrum leads a new upper limit on photon-ALP coupling, gaγ: using very...
We study the weak mixing of photons and relativistic axionlike particles (axions) in plasmas with background magnetic fields, $\mathbf{B}$. show that, to leading order axion-photon coupling, conversion probability, ${P}_{\ensuremath{\gamma}\ensuremath{\rightarrow}a}$, is given by one-dimensional power spectrum field components perpendicular particle trajectory. Equivalently, we express ${P}_{\ensuremath{\gamma}\ensuremath{\rightarrow}a}$ as Fourier transform autocorrelation function,...
In this paper, we explore the phenomenology of massive axionlike particles (ALPs) coupled to quarks and gluons, dubbed “QCD ALPs,” with an emphasis on associated low-energy observables. ALPs gluons not only induce nuclear interactions at scales below QCD scale, relevant for ALP production in supernovae (SNe), but naturally also couple photons similarly axion. We discuss link between high-energy formulation theories their effective couplings nucleons photons. The induced photon coupling...
We construct a class of random potentials for N >> 1 scalar fields using non-equilibrium matrix theory, and then characterize multifield inflation in this setting. By stipulating that the Hessian matrices adjacent coordinate patches are related by Dyson Brownian motion, we define potential vicinity trajectory. This method remains computationally efficient at large N, permitting us to study much larger systems than has been possible with other constructions. illustrate utility our approach...
We show that the soft X-ray excess in Coma cluster can be explained by a cosmic background of relativistic axions converting into photons magnetic field. provide detailed self-contained review excess, proposed astrophysical explanations and problems they face, explain how 0.1-1 keV axion naturally arises at reheating many string theory models early universe. study morphology numerically propagating through stochastic, multi-scale field are consistent with observations Faraday rotation...
We construct a new class of metastable de Sitter vacua flux compactifications type IIB string theory. These solutions provide natural extension the `Large Volume Scenario' anti-de vacua, and can analogously be realised at parametrically large volume weak coupling, using standard ${\cal N}=1$ supergravity. For these positive vacuum energy is achieved from inclusion small amount flux-induced supersymmetry breaking in complex structure axio-dilaton sector, no additional `uplift' contribution...
Axions and photons resonantly interconvert in regions where the plasma frequency approximately equals axion mass. This process is directly analogous to an avoided level crossing quantum mechanics, for which celebrated Landau-Zener (LZ) formula provides a simple, non-perturbative solution conversion probability. The LZ commonly used studies of axion-photon conversion; however, this context, it relies on assumption that magnetic field variation small compared variations frequency, frequently...
We construct models of inflation with many randomly interacting fields and use these to study the generation cosmological observables. model potentials as multi-dimensional Gaussian random (GRFs) identify powerful algebraic simplifications that, for first time, make it possible access manyfield limit in GRF potentials. Focussing on small-field, slow-roll, approximate saddle-point structure sub-Planckian scales, we explicit examples involving up 100 generate statistical ensembles comprising...
Future cosmological surveys will probe the expansion history of Universe and constrain phenomenological models dark energy. Such do not address fine-tuning problem vacuum energy, i.e., constant (CCP), but can make it spectacularly worse. We show that this is case for "interacting energy" in which masses matter states depend on energy sector. If realized nature, these have far-reaching implications proposed solutions to CCP require number vacua exceed density. current estimates flux string...