arXiv subjects

A. Guerrero

Publications and source records attributed to A. Guerrero.

13 recordsLinked to original sources

arXiv2023

Unbiased surveys of dust-enshrouded galaxies using ALMA

The ALMA lensing cluster survey (ALCS) is a 96-hr large program dedicated to uncovering and characterizing intrinsically faint continuum sources and line emitters with the assistance of gravitational lensing. All 33 cluster fields were selected from HST/Spitzer treasury programs including CLASH, Hubble Frontier Fields, and RELICS, which also have Herschel and Chandra coverages. The total sky area surveyed reaches $\sim$133 arcmin$^2$ down to a depth of $\sim$60 $μ$Jy beam$^{-1}$ (1$σ$) at 1.2 mm, yielding 141 secure blind detections of continuum sources and additional 39 sources aided by priors. We present scientific motivation, survey design, the status of spectroscopy follow-up observations, and number counts down to $\sim$7 $μ$Jy. Synergies with JWST are also discussed.

astro-ph.GA↗

arXiv2019

Experimental observation of proton bunch modulation in a plasma, at varying plasma densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a density modulation resulting from radial wakefield effects with a period reciprocal to the plasma frequency. We show that the modulation is seeded by using an intense laser pulse co-propagating with the proton bunch which creates a relativistic ionization front within the bunch. We show by varying the plasma density over one order of magnitude that the modulation period scales with the expected dependence on the plasma density.

physics.acc-ph↗

arXiv2017

AWAKE readiness for the study of the seeded self-modulation of a 400\,GeV proton bunch

AWAKE is a proton-driven plasma wakefield acceleration experiment. % We show that the experimental setup briefly described here is ready for systematic study of the seeded self-modulation of the 400\,GeV proton bunch in the 10\,m-long rubidium plasma with density adjustable from 1 to 10$\times10^{14}$\,cm$^{-3}$. % We show that the short laser pulse used for ionization of the rubidium vapor propagates all the way along the column, suggesting full ionization of the vapor. % We show that ionization occurs along the proton bunch, at the laser time and that the plasma that follows affects the proton bunch. %

physics.plasm-ph↗

arXiv2017

The Spanish Space Weather Service SeNMEs. A case study on the Sun-Earth chain

The Spanish Space Weather Service SeNMEs, \url{www.senmes.es}, is a portal created by the SRG-SW of the Universidad de Alcalá, Spain, to meet societal needs of near real-time space weather services. This webpage-portal is divided in different sections to fulfill users needs about space weather effects: radio blackouts, solar energetic particle events, geomagnetic storms and presence of geomagnetically induced currents. In less than one year of activity, this service has released a daily report concerning the solar current status and interplanetary medium, informing about the chances of a solar perturbation to hit the Earth's environment. There are also two different forecasting tools for geomagnetic storms, and a daily ionospheric map. These tools allow us to nowcast a variety of solar eruptive events and forecast geomagnetic storms and their recovery, including a new local geomagnetic index, LDi{ñ}, along with some specific new scaling. In this paper we also include a case study analysed by SeNMEs. Using different high resolution and cadence data from space-borne solar telescopes SDO, SOHO and GOES, along with ionospheric and geomagnetic data, we describe the Sun-Earth feature chain for the event.

astro-ph.SR↗

arXiv2017

Flux emergence event underneath a filament

Flux emergence phenomena are relevant at different temporal and spatial scales. We have studied a flux emergence region underneath a filament. This filament elevated itself smoothly, and the associated CME reached Earth. In this study we investigate the size and amount of flux in the emergence event. The flux emergence site appeared just beneath a filament. The emergence acquired a size of 24 Mm in half a day. The unsigned magnetic flux density from LOS-magnetograms is around 1 kG at its maximum. The transverse field as well as the filament eruption were also analysed.

astro-ph.SR↗

arXiv2016

Redefining the boundaries of interplanetary coronal mass ejections from observations at the ecliptic plane

On 2015 January 6-7, an interplanetary coronal mass ejection (ICME) was observed at L1. This event, which can be associated with a weak and slow coronal mass ejection, allows us to discuss on the differences between the boundaries of the magnetic cloud and the compositional boundaries. A fast stream from a solar coronal hole surrounding this ICME offers a unique opportunity to check the boundaries' process definition and to explain differences between them. Using Wind and ACE data, we perform a complementary analysis involving compositional, magnetic, and kinematic observations providing relevant information regarding the evolution of the ICME as travelling away from the Sun. We propose erosion, at least at the front boundary of the ICME, as the main reason for the difference between the boundaries, and compositional signatures as the most precise diagnostic tool for the boundaries of ICMEs.

astro-ph.SR↗

arXiv2015

Supergranular-scale magnetic flux emergence beneath an unstable filament

Here we report evidence of a large solar filament eruption on 2013, September 29. This smooth eruption, which passed without any previous flare, formed after a two-ribbon flare and a coronal mass ejection towards Earth. The coronal mass ejection generated a moderate geomagnetic storm on 2013, October 2 with very serious localized effects. The whole event passed unnoticed to flare-warning systems. We have conducted multi-wavelength analyses of the Solar Dynamics Observatory through Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) data. The AIA data on 304, 193, 211, and 94 Åsample the transition region and the corona, respectively, while HMI provides photospheric magnetograms, continuum, and linear polarization data, in addition to the fully inverted data provided by HMI. [...] We have observed a supergranular-sized emergence close to a large filament in the boundary of the active region NOAA11850. Filament dynamics and magnetogram results suggest that the magnetic flux emergence takes place in the photospheric level below the filament. Reconnection occurs underneath the filament between the dipped lines that support the filament and the supergranular emergence. The very smooth ascent is probably caused by this emergence and torus instability may play a fundamental role, which is helped by the emergence.

astro-ph.SR↗

arXiv2015

A Carrington-like geomagnetic storm observed in the 21st century

In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the "Carrington-like" event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a) the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H) of terrestrial magnetic field depends strongly on magnetic local time (MLT); (b) the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents (FACs), and (c) the very local signatures of the H-spike imply that a Carrington-like event can occur more often than expected.

physics.geo-ph↗

arXiv2015

Entropy and complexity analysis of the D-dimensional rigid rotator and hyperspherical harmonics

In this paper we carry out an information-theoretic analysis of the $D$-dimensional rigid rotator by studying the entropy and complexity measures of its wavefunctions, which are controlled by the hyperspherical harmonics. These measures quantify single and two-fold facets of the rich intrinsic structure of the system which are manifest by the intricate and complex variety of D-dimensional geometries of the hyperspherical harmonics. We calculate the explicit expressions of the entropic moments and the Rényi entropies as well as the Fisher-Rényi, Fisher-Shannon and LMC complexities of the system. The explicit expression for the last two complexity measures is not yet possible, mainly because the logarithmic functional of the Shannon entropy has not yet been obtained up until now in a closed for

quant-ph↗

arXiv2014

Complexity analysis of hypergeometric orthogonal polynomials

The complexity measures of the Crámer-Rao, Fisher-Shannon and LMC (López-Ruiz, Mancini and Calvet) types of the Rakhmanov probability density $ρ_n(x)=ω(x) p_n^2(x)$ of the polynomials $p_n(x)$ orthogonal with respect to the weight function $ω(x)$, $x\in (a,b)$, are used to quantify various two-fold facets of the spreading of the Hermite, Laguerre and Jacobi systems all over their corresponding orthogonality intervals in both analytical and computational ways. Their explicit (Crámer-Rao) and asymptotical (Fisher-Shannon, LMC) values are given for the three systems of orthogonal polynomials. Then, these complexity-type mathematical quantities are numerically examined in terms of the polynomial's degree $n$ and the parameters which characterize the weight function. Finally, several open problems about the generalised hypergeometric functions of Lauricella and Srivastava-Daoust types, as well as on the asymptotics of weighted $L_q$-norms of Laguerre and Jacobi polynomials are pointed out.

math-ph↗

arXiv2014

Modeling the recovery phase of extreme geomagnetic storms

The recovery phase of the largest storms ever recorded has been studied. These events provide an extraordinary opportunity for two goals: (1) to validate the hyperbolic model by Aguado et al. [2010] for the recovery phase after disturbances as severe as the Carrington event, or that related to the Hydro-Quebec blackout in March 1989, and (2) to check whether the linear relationship between the recovery time and the intensity of the storm still complies. Our results reveal the high accuracy of the hyperbolic decay function to reproduce the recovery phase of the magnetosphere after an extreme storm. Moreover, the characteristic time that takes the magnetosphere to recover depends in an exponential way on the intensity of the storm, as indicated by the relationship between the two parameters involved in the hyperbolic decay. This exponential function can be approached by a linear function when the severity of the storm diminishes.

physics.geo-ph↗

arXiv2014

Solar sources of the geoeffective events in September 2011

We investigate the geoeffective events happened from 8 to 20 Sept 2011, analysing the most plausible solar sources of these events, where coronal mass ejections and coronal holes play a fundamental role. The physical properties of the coronal holes, such as area and magnetic field, are studied through the Solar Dynamics Observatory instruments: AIA 193 Å images and HMI longitudinal magnetograms. The active regions which are the origin of the coronal mass ejections are analysed in AIA and SoHO-LASCO data.

astro-ph.SR↗

arXiv2013

Information-theoretic-based spreading measures of orthogonal polynomials

The macroscopic properties of a quantum system strongly depend on the spreading of the physical eigenfunctions (wavefunctions) of its Hamiltonian operador over its confined domain. The wavefunctions are often controlled by classical or hypergeometric-type orthogonal polynomials (Hermite, Laguerre and Jacobi). Here we discuss the spreading of these polynomials over its orthogonality interval by means of various information-theoretic quantities which grasp some facets of the polynomial distribution not yet analyzed. We consider the information-theoretic lengths closely related to the Fisher information and Rényi and Shannon entropies, which quantify the polynomial spreading far beyond the celebrated standard deviation.

math-ph↗