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First comments on a descoped/staged FCC-ee
No full textInternational audienceIn response to its remit, the European Strategy Group (ESG) recommended the electron-positron Future Circular Collider (FCC-ee) as the preferred option for the next flagship collider at CERN; and a descoped FCC-ee as the preferred alternative option (with reduced synchrotron radiation (SR) power, without a run at the threshold, and with only two interaction regions) in the event that the preferred option turns out not to be feasible. Upon request of the ESG, a basic comparison of the physics potential of the descoped option with that of the baseline version is presented in this short note. Our first observations about the alternative proposal of a descoped FCC-ee are that (i) the same performance as the baseline, apart from -run related, is achieved with the longer proposed period of operation; and (ii) the top run remains essential, but can be staged at a later date. The full appraisal of the consequences of descoping and a proposal for the best way to integrate possible staging wherever feasible, and possible improvements, will need further joint studies by the physics and accelerator groups
ZTF SN Ia DR2 follow-up: Characterization of subluminous Type Ia supernovae in the ZTF DR2 full sample
No full textInternational audienceThe Zwicky Transient Facility Data Release 2 (ZTF DR2) includes a total of 3,628 Type Ia supernovae (SNe~Ia), providing the largest and most complete sample of spectroscopically confirmed SNe~Ia at low redshift to date. In this paper, we present a photometric and spectroscopic analysis of 124 subluminous SNe~Ia, the largest sample of spectroscopically classified subluminous SNe~Ia observed with a single instrument, comprising 87 91bg-like, 12 86G-like, 18 04gs-like, and 7 02es-like events. We complement the published DR2 SALT2 light-curve parameters with new parameters obtained using template-based fits from SNooPy. Expansion velocities and pseudo-equivalent widths pEW of key spectral features are measured using Spextractor, and spectral averages are constructed for each subluminous subtype, binned by phase. We also analyze the host galaxy environments, both global and local, in terms of color, stellar mass, and directional light radius . We find that all subluminous SNe~Ia (except the 02es-like subtype) are intrinsically red. This is evident by separating extrinsic from intrinsic color components. Since SALT2 is not trained on subluminous SNe~Ia, it compensates for their redder colors by inflating the parameter, thus extending the luminosity-width relation to negative values of x1. As expected, all subluminous SNe~Ia fall within the Cool region of the Branch et al. (2006) diagram, with the exception of 02es-like events, which show lower Si II 5972 pEW values. All subluminous subtypes tend to occur in more massive, redder host galaxies, and in the reddest local environments. Notably, 91bg- and 86G-like SNe~Ia explode at significantly larger normalized galactocentric distances. Finally, we identify the of the blended Ti II+Si II+Mg II absorption feature at 4300~A, along with s_BV, as robust and sufficient indicators for subclassifying subluminous SNe~Ia
H.E.S.S. detection and multi-wavelength study of the 1 blazar PKS 034627
No full textInternational audiencePKS 0346-27 is a Low Synchrotron Peaked (LSP) blazar at redshift 0.991. The very-high-energy (VHE, E > 100 GeV) spectra of blazars are always affected by absorption by the Extragalactic Background Light (EBL) and subsequently, no blazars have been detected in VHE -rays at redshifts exceeding 1. Extending the redshift range of VHE-detected blazars to will yield insights into the cosmological evolution of both the VHE blazar population and the EBL. This is the goal of a target-of-opportunity (ToO) programme by H.E.S.S. to observe flaring high-redshift () blazars. We report on H.E.S.S. ToO and multi-wavelength observations of the blazar PKS 034627. Along with H.E.S.S., simultaneous data from {\it Fermi}-LAT, {\it Swift} (XRT and UVOT), and ATOM have been analysed and modelled using single-zone leptonic and hadronic models. PKS~0346-27 has been detected by H.E.S.S at a significance of 6.3 during one night, on 3 November 2021, while for other nights before and after this day, upper limits on the VHE flux are determined. No evidence for intra-night -ray variability has been found. A flare in high-energy (HE, ~MeV) -rays detected by {\it Fermi}-LAT preceded the H.E.S.S. detection by 2 days. A fit with a single-zone emission model to the contemporaneous spectral energy distribution during the detection night was possible with a proton-synchrotron-dominated hadronic model, requiring a proton-kinetic-energy-dominated jet power temporarily exceeding the source's Eddington limit, although alternative (e.g. multi-zone) models can not be ruled out. A one-zone leptonic model is, in principle, also able to fit the flare-state SED, however, requiring implausible parameter choices, in particular, extreme Doppler and bulk Lorentz factors of
Measurement of the Cm neutron capture cross section at the n_TOF facility at CERN
No full textInternational audienceAccurate neutron capture cross section data for minor actinides are essential for the safe and efficient management of high level radioactive waste produced during the operation of nuclear reactors. In particular, 244Cm, with a half-life of 18.11 years, dominates neutron emission in spent fuel and also contributes significantly to the decay heat and radiotoxicity. Furthermore, neutron capture on 244Cm opens the pathway for the formation of heavier isotopes such as Bk, Cf, and other Cm isotopes. Sensitivity studies for present and future nuclear reactors have highlighted the need to reduce the uncertainties in the 244Cm capture cross section. Experimental data on the capture cross section of this isotope are scarce due to the challenges associated with its measurements. Prior to the presented measurement and two recent measurements conducted at J-PARC, only one set of data for the 244Cm capture cross section existed, obtained in 1969 during an underground nuclear explosion experiment. The capture cross section of 244Cm has been measured at the n_TOF facility at CERN with three different experimental setups: one at Experimental Area 1 (EAR1) using the Total Absorption Calorimeter and two measurements at Experimental Area 2 (EAR2) with CD detectors, employing two different samples. The results from these three measurements were found to be compatible and then combined. In total, 17 resonances of 244Cm were measured at n_TOF below 300 eV. The radiative kernels obtained in this measurement are in good agreement with JENDL-4.0 for the majority of the resonances. Additionally, they are compatible with the recent JENDL-5 library below 50 eV, while at higher energies, the majority of radiative kernels from this evaluation based on the recent measurement by Kawase et al., are not compatible. Additionally, the 244Cm samples also contained 240Pu. Resonances of this isotope were analyzed in the energy range between 20 and 180 eV, and the results were found to be consistent with previous measurements and evaluations, that enhances confidence in the 244Cm results
Kinematic lensing with high-resolution spectroscopic surveys. A unique opportunity for transformative cosmology at high redshifts in the 2040s
No full textInternational audienceWe present a science case to perform high-redshift cosmic shear surveys for cosmology with next-generation spectroscopic instruments, such as the proposed MegaMapper and Wide-field Spectroscopic Telescope. We argue that by using the novel technique called 'kinematic lensing' (KL) it will be possible to obtain shear catalogues at redshifts between 2 and 5. We show that the signal-to-noise ratio of KL at such high redshifts is on average twice as much that expected from current weak lensing (WL) surveys such as Euclid or LSST, and several times that of the previous generation of WL surveys like DES and KiDS, even with very conservative assumptions about the fraction of spectroscopically-detected sources for which KL shear estimates will be available. This will allow cosmologists to perform joint galaxy clustering-cosmic shear analyses over unprecedented cosmic volumes and to probe the growth of structures deep in the matter-dominated era and across the onset of dark-energy domination, offering a unique opportunity to unveil the mystery of cosmic acceleration
Does Memory Burden Open a New Mass Window for Primordial Black Holes as Dark Matter?
No full textInternational audienceIt has been argued that the so-called memory-burden effect could cause black holes to become stabilized by the information that they carry, thereby suppressing the rate at which they undergo Hawking evaporation. It has furthermore been suggested that this opens a new mass window, between , over which primordial black holes could constitute the dark matter of our Universe. We show in this \textit{letter} that this is true only if the transition from the semi-classical phase of a black hole to its memory-burdened phase is practically instantaneous. If this transition is instead more continuous, Hawking evaporation will persist at relevant levels throughout the eras of Big Bang Nucleosynthesis and recombination, leading to stringent constraints which rule out the possibility that black holes lighter than could make up all or most of the dark matter
The Online Data Filter for the KM3NeT Neutrino Telescopes
No full textInternational audienceThe KM3NeT research infrastructure comprises two neutrino telescopes located in the deep waters of the Mediterranean Sea, namely ORCA and ARCA. KM3NeT/ORCA is designed for the measurement of neutrino properties and KM3NeT/ARCA for the detection of high\nobreakdashes-energy neutrinos from the cosmos. Neutrinos are indirectly detected using three\nobreakdashes-dimensional arrays of photo\nobreakdashes-sensors which detect the Cherenkov light that is produced when relativistic charged particles emerge from a neutrino interaction. The analogue pulses from the photo\nobreakdashes-sensors are digitised offshore and all digital data are sent to a station on shore where they are processed in real time using a farm of commodity servers and custom software. In this paper, the design and performance of the software that is used to filter the data are presented. The performance of the data filter is evaluated in terms of its purity, capacity and efficiency. The purity is measured by a comparison of the event rate caused by muons produced by cosmic ray interactions in the Earth's atmosphere with the event rate caused by the background from decays of radioactive elements in the sea water and bioluminescence. The capacity is measured by the minimal number of servers that is needed to sustain the rate of incoming data. The efficiency is measured by the effective volumes of the sensor arrays
The HYDRA pion-tracker for hypernuclei studies at R3B
No full textInternational audienceThe HYpernuclei-Decay at R3B Apparatus (HYDRA) tracker is a novel time projection chamber combined with a plastic scintillator wall for timing and trigger purposes. This detector is a low radiation length tracker dedicated to measuring pions from the weak decay of light hypernuclei produced from ion-ion collisions at few GeV/nucleon in the magnetic field of the large-acceptance dipole magnet GLAD at the Reactions with Relativistic Radioactive Beams (R3B) experiment at GSI-FAIR. In this paper, we describe the design of the detector and provide the results of its first characterizations
Probing fundamental physics with Extreme Mass Ratio Inspirals: a full Bayesian inference for scalar charge
No full textInternational audienceExtreme Mass Ratio Inspirals (EMRIs) are key sources for the future space-based gravitational wave detector LISA, and are considered promising probes of fundamental physics. Here, we present the first complete Bayesian analysis of EMRI signals in theories with an additional massless scalar, which could arise in an extension of General Relativity or of the Standard Model of Particle Physics. We develop a waveform model accurate at adiabatic order for equatorial eccentric orbits around spinning black holes. Using full Bayesian inference, we forecast LISA's ability to probe the presence of new fundamental fields with EMRI observations