IFAE

About: IFAE is a other organization based out in Barcelona, Spain. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 664 authors who have published 1270 publications receiving 51097 citations. The organization is also known as: Instituto de Fisica de Altas Energias & IFAE.

The blazar TXS 0506+056 associated with a high-energy neutrino: insights into extragalactic jets and cosmic ray acceleration

Abstract: A neutrino with energy of $\sim$290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS~0506+056 during enhanced gamma-ray activity, with chance coincidence being rejected at $\sim 3\sigma$ level. We monitored the object in the very-high-energy (VHE) band with the MAGIC telescopes for $\sim$41 hours from 1.3 to 40.4 days after the neutrino detection. Day-timescale variability is clearly resolved. We interpret the quasi-simultaneous neutrino and broadband electromagnetic observations with a novel one-zone lepto-hadronic model, based on interactions of electrons and protons co-accelerated in the jet with external photons originating from a slow-moving plasma sheath surrounding the faster jet spine. We can reproduce the multiwavelength spectra of TXS 0506+056 with neutrino rate and energy compatible with IceCube-170922A, and with plausible values for the jet power of $\sim 10^{45} - 4 \times 10^{46} {\rm erg \ s^{-1}}$. The steep spectrum observed by MAGIC is concordant with internal $\gamma\gamma$ absorption above a few tens of GeV entailed by photohadronic production of a $\sim$290 TeV neutrino, corroborating a genuine connection between the multi-messenger signals. In contrast to previous predictions of predominantly hadronic emission from neutrino sources, the gamma-rays can be mostly ascribed to inverse Compton up-scattering of external photons by accelerated electrons. The X-ray and VHE bands provide crucial constraints on the emission from both accelerated electrons and protons. We infer that the maximum energy of protons in the jet co-moving frame can be in the range $\sim 10^{14}$ to $10^{18}$ eV.

Status and First Results of the MAGIC Telescope

Abstract: The 17 m MAGIC Cherenkov telescope for gamma ray astronomy between 30 and 300 GeV started operations in its final configuration in October 2003 and is currently well into its calibration phase. Here I report on its present status and its first gamma ray source detections.

Higgsino dark matter in the MSSM

Abstract: A cosmologically stable neutral component from a nearly pure $SU(2)$ doublet, with a mass $\ensuremath{\sim}1.1\text{ }\text{ }\mathrm{TeV}$, is one appealing candidate for dark matter (DM) consistent with all direct dark matter searches. We explore this possibility in the context of the minimal supersymmetric extension of the Standard Model, with the Higgsino playing the role of DM, in theories where supersymmetry breaking is transmitted by gravitational interactions at the unification scale $M\ensuremath{\simeq}2\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{GeV}$. We focus on the search for ``light'' supersymmetric spectra, which could be within reach of present and/or future colliders, in models with universal and nonuniversal Higgs and gaugino Majorana masses. The lightest supersymmetric particles of the spectrum are, by construction, two neutralinos and one chargino, almost degenerate, with a mass $\ensuremath{\sim}1.1\text{ }\text{ }\mathrm{TeV}$, and a mass splitting of a few GeV. Depending on the particular scenario the gluino can be at its experimental lower mass bound $\ensuremath{\sim}2.2\text{ }\text{ }\mathrm{TeV}$; in the squark sector, the lightest top squark can be as light as $\ensuremath{\sim}1.6\text{ }\text{ }\mathrm{TeV}$, and the lightest slepton, the right-handed stau, can have a mass as light as 1.2 TeV. The lightest neutralino can be found in the next generation of direct dark matter experimental searches. In the most favorable situation, the gluino, with some specific decay channels, could be found during the next run of the LHC, and the lightest top squark during the high-luminosity LHC run.

The impact of spectroscopic incompleteness in direct calibration of redshift distributions for weak lensing surveys

Abstract: Obtaining accurate distributions of galaxy redshifts is a critical aspect of weak lensing cosmology experiments. One of the methods used to estimate and validate redshift distributions is to apply weights to a spectroscopic sample, so that their weighted photometry distribution matches the target sample. In this work, we estimate the selection bias in redshift that is introduced in this procedure. We do so by simulating the process of assembling a spectroscopic sample (including observer-assigned confidence flags) and highlight the impacts of spectroscopic target selection and redshift failures. We use the first year (Y1) weak lensing analysis in Dark Energy Survey (DES) as an example data set but the implications generalize to all similar weak lensing surveys. We find that using colour cuts that are not available to the weak lensing galaxies can introduce biases of up to Delta z similar to 0.04 in the weighted mean redshift of different redshift intervals (Delta z similar to 0.015 in the case most relevant to DES). To assess the impact of incompleteness in spectroscopic samples, we select only objects with high observer-defined confidence flags and compare the weighted mean redshift with the true mean. We find that the mean redshift of the DES Y1 weak lensing sample is typically biased at the Delta z = 0.005-0.05 level after the weighting is applied. The bias we uncover can have either sign, depending on the samples and redshift interval considered. For the highest redshift bin, the bias is larger than the uncertainties in the other DES Y1 redshift calibration methods, justifying the decision of not using this method for the redshift estimations. We discuss several methods to mitigate this bias.

Scale invariant solids

Abstract: Scale invariance (SI) can in principle be realized in the elastic response of solid materials. There are two basic options: that SI is a manifest symmetry or that it is spontaneously broken. The manifest case corresponds physically to the existence of a nontrivial infrared fixed point with phonons among its degrees of freedom. We use simple bottom-up $\mathrm{AdS}/\mathrm{CFT}$ constructions to model this case. We characterize the types of possible elastic response and discuss how the sound speeds can be realistic, that is, sufficiently small compared to the speed of light. We also study the spontaneously broken case using effective field theory (EFT) methods. We present a new one-parameter family of nontrivial EFTs that includes the previously known ``conformal solid'' as a particular case as well as others which display small sound speeds. We also point out that an emergent Lorentz invariance at low energies could affect by order-one factors the relation between sound speeds and elastic moduli.