arXiv subjects

M. Maggiore

Publications and source records attributed to M. Maggiore.

At least 19 recordsLinked to original sources

arXiv2026

Hunting Dark Matter with the Einstein Telescope

Too light primordial black holes evaporate and are therefore strongly constrained by various bounds, e.g. Cosmic Microwave Background distortion. However, if they are formed strongly clustered, the corresponding haloes may collapse in heavier black holes which may form the entirety of the dark matter of the universe. The indirect signal of such scenario is the production of a flat stochastic background of gravitational waves which is detectable by the Einstein Telescope.

astro-ph.CO↗

arXiv2025

Uncovering the population of compact binary mergers and their formation pathways with gravitational waves through the Einstein Telescope

Ground-based gravitational-wave (GW) observatories have transformed our view of compact-object mergers, yet their reach still limits a comprehensive reconstruction of the processes that generate these systems. Only next-generation observatories, with order-of-magnitude improvements in sensitivity and access to lower frequencies, will be capable of radically extending this detection horizon. GW observations will make it possible to detect the complete population of binary black hole (BBH) mergers out to redshifts of $z \simeq 100$. This capability will deliver an unprecedented map of merger events across cosmic time and enable precise reconstruction of their mass and spin distributions, while for several thousand events the signal-to-noise ratio will surpass 100, enabling precision physics of BHs and neutron stars (NSs). The access to lower frequencies will also open the intermediate-mass window, detecting systems of order $\sim 10^3 M_\odot$, potentially in coordination with multi-band observations from LISA. At higher redshifts, where Population III stars have so far remained beyond reach - even for the James Webb Space Telescope - GW observations by next-generation detectors will routinely provide observations of BH mergers thought to originate from these primordial stellar populations. Such measurements are expected to play a central role in clarifying the early assembly of supermassive black holes. A single detection of a binary BH system at $z \gtrsim 30$, or of a compact object with sub-solar mass and no tidal deformability, would constitute strong evidence for the existence of primordial black holes. Such a discovery would have profound consequences for our understanding of dark matter and the early Universe. Ultimately, the GW observations will become revolutionary for identifying the physical channels responsible for compact binary formation.

astro-ph.HE↗

arXiv2023

Realization and simulations of the new SPES Beam Cooler

In order to allow a good separation of isotopes in a High Resolution Mass Spectrometer (HRMS), the transverse emittance and the energy spread of the beam should have very low values, for this reason a Beam Cooler (BC) is planned to be located between the ISOL target, i.e. the beam source, and the HRMS in the new project Selective Production of Exotic Species (SPES). In the SPES project the spectrometer resolution must be higher than dm/m=5E-5 and thus the features of the beam at the entrance of the HRMS should be at least emittance (95%, normalized) < 8.3E-3 pi mm mrad and sigma_E < 1.5eV. A new BC has been designed and realized by the Laboratoire de Physique Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori Nazionali di Legnaro (LNL), near Padova, Italy. BCs cool down the beam thanks to a dissipative process in which the thermal energy passes from the beam ions to another medium whose constituent is typically much lighter, Helium gas in our case. This process takes place inside a confinement system that on the one hand to limit the spread of the cooling medium, and on the other to allow the beam to continue along the required trajectory, in the presented device it is a row of radio frequency quadrupoles in an almost closed chamber. This document presents the main features of the new BC together with the results of a preliminary study where the beam dynamic has been simulated. The analysis embeds also the investigation of the gas distribution inside and outside the BC. The beam dynamic simulations are based on the Simion code while the estimation of the gas distribution is computed with MolFlow+. Simulations show that accurately setting the BC leads to a large improvement of the emittance while the energy spread still needs to be improved. Limiting the gas pressure in the acceleration zone seems to allow the required final boost.

physics.acc-ph↗

arXiv2023

Searching for Primordial Black Holes with the Einstein Telescope: impact of design and systematics

Primordial Black Holes (PBHs) have recently attracted much attention as they may explain some of the LIGO/Virgo/KAGRA observations and significantly contribute to the dark matter in our universe. The next generation of Gravitational Wave (GW) detectors will have the unique opportunity to set stringent bounds on this putative population of objects. Focusing on the Einstein Telescope (ET), in this paper we analyse in detail the impact of systematics and different detector designs on our future capability of observing key quantities that would allow us to discover and/or constrain a population of PBH mergers. We also perform a population analysis, with a mass and redshift distribution compatible with the current observational bounds. Our results indicate that ET alone can reach an exquisite level of accuracy on the key observables considered, as well as detect up to tens of thousands of PBH binaries per year, but for some key signatures (in particular high--redshift sources) the cryogenic instrument optimised for low frequencies turns out to be crucial, both for the number of observations and the error on the parameters reconstruction. As far as the detector geometry is concerned, we find that a network consisting of two separated L--shaped interferometers of 15 (20)~km arm length, oriented at $45^{\circ}$ with respect to each other performs better than a single triangular shaped instrument of 10 (15)~km arm length, for all the metrics considered.

gr-qc↗

arXiv2022

Design of the ELIMAIA ion collection system

A system of permanent magnet quadrupoles (PMQs) is going to be realized by INFNLNS to be used as a collection system for the injection of laser driven ion beams up to 60 AMeV in an energy selector based on four resistive dipoles. This system is the first element of the ELIMED (ELI-Beamlines MEDical and Multidisciplinary applications) beam transport, dosimetry and irradiation line that will be developed by INFN-LNS (It) and installed at the ELI-Beamlines facility in Prague (Cz). ELIMED will be the first users open transport beam-line where a controlled laser-driven ion beam will be used for multidisciplinary researches. The definition of well specified characteristics, both in terms of performances and field quality, of the magnetic lenses is crucial for the system realization, for the accurate study of the beam dynamics and for the proper matching with the magnetic selection system which will be designed in the next months. Here, we report the design of the collection system and the adopted solutions in order to realize a robust system form the magnetic point of view. Moreover, the first preliminary transport simulations are also described.

physics.acc-ph↗

arXiv2021

Synergies of THESEUS with the large facilities of the 2030s and guest observer opportunities

The proposed THESEUS mission will vastly expand the capabilities to monitor the high-energy sky, and will exploit large samples of gamma-ray bursts to probe the early Universe back to the first generation of stars, and to advance multi-messenger astrophysics by detecting and localizing the counterparts of gravitational waves and cosmic neutrino sources. The combination and coordination of these activities with multi-wavelength, multi-messenger facilities expected to be operating in the thirties will open new avenues of exploration in many areas of astrophysics, cosmology and fundamental physics, thus adding considerable strength to the overall scientific impact of THESEUS and these facilities. We discuss here a number of these powerful synergies.

astro-ph.IM↗

arXiv2019

Towards a non-singular pre-big bang cosmology

We discuss general features of the $β$-function equations for spatially flat, $(d+1)$-dimensional cosmological backgrounds at lowest order in the string-loop expansion, but to all orders in $α'$. In the special case of constant curvature and a linear dilaton these equations reduce to $(d+1)$ algebraic equations in $(d+1)$ unknowns, whose solutions can act as late-time regularizing attractors for the singular lowest-order pre-big bang solutions. We illustrate the phenomenon in a first order example, thus providing an explicit realization of the previously conjectured transition from the dilaton to the string phase in the weak coupling regime of string cosmology. The complementary role of $α'$ corrections and string loops for completing the transition to the standard cosmological scenario is also briefly discussed.

hep-th↗

arXiv2019

Testing modified gravity at cosmological distances with LISA standard sirens

Modifications of General Relativity leave their imprint both on the cosmic expansion history through a non-trivial dark energy equation of state, and on the evolution of cosmological perturbations in the scalar and in the tensor sectors. In particular, the modification in the tensor sector gives rise to a notion of gravitational-wave (GW) luminosity distance, different from the standard electromagnetic luminosity distance, that can be studied with standard sirens at GW detectors such as LISA or third-generation ground based experiments. We discuss the predictions for modified GW propagation from some of the best studied theories of modified gravity, such as Horndeski or the more general degenerate higher order scalar-tensor (DHOST) theories, non-local infrared modifications of gravity, bigravity theories and the corresponding phenomenon of GW oscillation, as well as theories with extra or varying dimensions. We show that modified GW propagation is a completely generic phenomenon in modified gravity. We then use a simple parametrization of the effect in terms of two parameters $(Ξ_0,n)$, that is shown to fit well the results from a large class of models, to study the prospects of observing modified GW propagation using supermassive black hole binaries as standard sirens with LISA. We construct mock source catalogs and perform detailed Markov Chain Monte Carlo studies of the likelihood obtained from LISA standard sirens alone, as well as by combining them with CMB, BAO and SNe data to reduce the degeneracies between cosmological parameters. We find that the combination of LISA with the other cosmological datasets allows one to measure the parameter $Ξ_0$ that characterizes modified GW propagation to the percent level accuracy, sufficient to test several modified gravity theories. [Abridged]

astro-ph.CO↗

arXiv2012

Multimegawatt DAE$δ$ALUS Cyclotrons for Neutrino Physics

DAE$δ$ALUS (Decay-At-rest Experiment for $δ_{CP}$ studies At the Laboratory for Underground Science) provides a new approach to the search for CP violation in the neutrino sector. High-power continuous-wave proton cyclotrons efficiently provide the necessary proton beams with an energy of up to 800 MeV to create neutrinos from pion and muon decay-at-rest. The experiment searches for $\barν_μ \rightarrow \barν_e$ at short baselines corresponding to the atmospheric $Δm^2$ region. The $\barν_e$ will be detected via inverse beta decay. Thus, the cyclotrons will be employed at a future ultra-large gadolinium-doped water or scintillator detector. In this paper we address the most challenging questions regarding a cyclotron-based high-power proton driver in the megawatt range with a kinetic energy of 800 MeV. Aspects of important subsystems like the ion source and injection chain, the magnet design and radio frequency system will be addressed. Precise beam dynamics simulations, including space charge and the $\text{H}_2^+$ stripping process, are the base for the characterization and quantification of the beam halo -- one of the most limiting processes in high-power particle accelerators.

physics.acc-ph↗

arXiv2011

Preliminary Design Study of High-Power H2+ Cyclotrons for the DAEdALUS Experiment

This report provides a first design for H2+ accelerators as the DAEdALUS neutrino sources. A description of all aspects of the system, from the ion source to the extracted beam, is provided. The analysis provides a first proof of principle of a full cyclotron system which can provide the necessary beam power for the CP violation search proposed by the DAEdALUS Collaboration.

physics.acc-ph↗

arXiv2011

A multi megawatt ring cyclotron to search for CP violation in the neutrino sector

A new approach to search for CP violation in the neutrino sector [1,2] is proposed by the experiment called DAEδALUS (Decay At rest Experiment for δcp At Laboratory for Underground Science). DAEδALUS needs three sources of neutrino fluxes, each one located at 1.5, 8 and 20 km from the underground detector. Here we present the study for a Superconducting Ring Cyclotron able to accelerate the H2+ molecules and to deliver proton beam with maximum energy of 800 MeV and the required high power. The magnetic field produced by the proposed superconducting magnetic sector, simulated by the code TOSCA, the isochronous magnetic field, some preliminary feature on the beam dynamic and the magnetic forces acting on the coils are here presented.

physics.acc-ph↗

arXiv2010

A Multi Megawatt Cyclotron Complex to Search for CP Violation in the Neutrino Sector

A Multi Megawatt Cyclotron complex able to accelerate H2+ to 800 MeV/amu is under study. It consists of an injector cyclotron able to accelerate the injected beam up to 50 MeV/n and of a booster ring made of 8 magnetic sectors and 8 RF cavities. The magnetic field and the forces on the superconducting coils are evaluated using the 3-D code OPERA. The injection and extraction trajectories are evaluated using the well tested codes developed by the MSU group in the '80s. The advantages to accelerate H2+ are described and preliminary evaluations on the feasibility and expected problems to build the injector cyclotron and the ring booster are here presented.

physics.ins-det↗

arXiv2010

IGEC2: A 17-month search for gravitational wave bursts in 2005-2007

We present here the results of a 515 days long run of the IGEC2 observatory, consisting of the four resonant mass detectors ALLEGRO, AURIGA, EXPLORER and NAUTILUS. The reported results are related to the fourfold observation time from Nov. 6 2005 until Apr. 14 2007, when Allegro ceased its operation. This period overlapped with the first long term observations performed by the LIGO interferometric detectors. The IGEC observations aim at the identification of gravitational wave candidates with high confidence, keeping the false alarm rate at the level of 1 per century, and high duty cycle, namely 57% with all four sites and 94% with at least three sites in simultaneous observation. The network data analysis is based on time coincidence searches over at least three detectors: the four 3-fold searches and the 4-fold one are combined in a logical OR. We exchanged data with the usual blind procedure, by applying a unique confidential time offset to the events in each set of data. The accidental background was investigated by performing sets of 10^8 coincidence analyses per each detector configuration on off-source data, obtained by shifting the time series of each detector. The thresholds of the five searches were tuned so as to control the overall false alarm rate to 1/century. When the confidential time shifts was disclosed, no gravitational wave candidate was found in the on-source data. As an additional output of this search, we make available to other observatories the list of triple coincidence found below search thresholds, corresponding to a false alarm rate of 1/month.

gr-qc↗

arXiv2008

All-sky search of NAUTILUS data

A search for periodic gravitational-wave signals from isolated neutron stars in the NAUTILUS detector data is presented. We have analyzed half a year of data over the frequency band $<922.2; 923.2>$ Hz, the spindown range $<-1.463\times10^{-8}; 0>$ Hz/s and over the entire sky. We have divided the data into 2 day stretches and we have analyzed each stretch coherently using matched filtering. We have imposed a low threshold for the optimal detection statistic to obtain a set of candidates that are further examined for coincidences among various data stretches. For some candidates we have also investigated the change of the signal-to-noise ratio when we increase the observation time from two to four days. Our analysis has not revealed any gravitational-wave signals. Therefore we have imposed upper limits on the dimensionless gravitational-wave amplitude over the parameter space that we have searched. Depending on frequency, our upper limit ranges from $3.4 \times 10^{-23}$ to $1.3 \times 10^{-22}$. We have attempted a statistical verification of the hypotheses leading to our conclusions. We estimate that our upper limit is accurate to within 18%.

gr-qc↗

arXiv2007

All-sky incoherent search for periodic signals with Explorer 2005 data

The data collected during 2005 by the resonant bar Explorer are divided into segments and incoherently summed in order to perform an all-sky search for periodic gravitational wave signals. The parameter space of the search spanned about 40 Hz in frequency, over 23927 positions in the sky. Neither source orbital corrections nor spindown parameters have been included, with the result that the search was sensible to isolated neutron stars with a frequency drift less than 6 X 10^{-11} Hz/s. No gravitational wave candidates have been found by means of the present analysis, which led to a best upper limit of 3.1 X 10^{-23} for the dimensionless strain amplitude.

gr-qc↗

arXiv2001

Supersymmetric Phase Transitions and Gravitational Waves at LISA

Gravitational waves generated during a first-order electroweak phase transition have a typical frequency which today falls just within the band of the planned space interferometer LISA. Contrary to what happens in the Standard Model, in its supersymmetric extensions the electroweak phase transition may be strongly first order, providing a mechanism for generating the observed baryon asymmetry in the Universe. We show that during the same transition the production of gravitational waves can be rather sizable. While the energy density in gravitational waves can reach at most $h_0^2 Ω_{\rm gw}\simeq 10^{-16}$ in the Minimal Supersymmetric Standard Model, in the Next-to-Minimal Supersymmetric Model, in some parameter range, $h_0^2 Ω_{\rm gw}$ can be as high as $4\times 10^{-11}$. A stochastic background of gravitational waves of this intensity is within the reach of the planned sensitivity of LISA. Since in the Standard Model the background of gravitational waves is totally neglegible, its detection would also provide a rather unexpected experimental signal of supersymmetry and a tool to descriminate among supersymmetric models with different Higgs content.

hep-ph↗

arXiv1997

Expanding and contracting universes in third quantized string cosmology

We discuss the possibility of quantum transitions from the string perturbative vacuum to cosmological configurations characterized by isotropic contraction and decreasing dilaton. When the dilaton potential preserves the sign of the Hubble factor throughout the evolution, such transitions can be represented as an anti-tunnelling of the Wheeler--De Witt wave function in minisuperspace or, in a third-quantization language, as the production of pairs of universes out of the vacuum.

hep-th↗

arXiv1996

Spectrum of relic gravitational waves in string cosmology

We compute the spectrum of relic gravitons in a model of string cosmology. In the low- and in the high-frequency limits we reproduce known results. The full spectrum, however, also displays a series of oscillations which could give a characteristic signature at the planned LIGO/VIRGO detectors. For special values of the parameters of the model the signal reaches its maximum already at frequencies accessible to LIGO and VIRGO and it is close to the sensitivity of first generation experiments.

gr-qc↗