arXiv subjects

M. Miceli

Publications and source records attributed to M. Miceli.

At least 37 records · Page 2Linked to original sources

arXiv2023

Virtual reality for the analysis and visualization of scientific numerical models

The complexity of the data generated by (magneto)-hydrodynamic (HD/MHD) simulations requires advanced tools for their analysis and visualization. The dramatic improvements in virtual reality (VR) technologies have inspired us to seek the long-term goal of creating VR tools for scientific model analysis and visualization that would allow researchers to study and perform data analysis on their models within an immersive environment. Here, we report the results obtained at INAF-Osservatorio Astronomico di Palermo in the development of these tools, which would allow for the exploration of 3D models interactively, resulting in highly detailed analysis that cannot be performed with traditional data visualization and analysis platforms. Additionally, these VR-based tools offer the ability to produce high-impact VR content for efficient audience engagement and awareness.

cs.HC↗

arXiv2022

Polarized radio emission unveils the structure of the pre-supernova circumstellar magnetic field and the radio emission in SN1987A

The detected polarized radio emission from remnant of SN1987A opens the possibility to unveil the structure of the pre-supernova magnetic field in the circumstellar medium. Properties derived from direct measurements would be of importance for understanding the progenitor stars and their magnetic fields. As the first step to this goal, we adopted the hydrodynamic data from an elaborated three-dimensional (3-D) numerical model of SN1987A. We have developed an approximate method for `reconstruction' of 3-D magnetic field structure inside supernova remnant on the `hydrodynamic background'. This method uses the distribution of the magnetic field around the progenitor as the initial condition. With such a 3-D magneto-hydrodynamic model, we have synthesized the polarization maps for a number of SN1987A models and compared them to the observations. In this way, we have tested different initial configurations of the magnetic field as well as a structure of the synchrotron emission in SN987A. We have recovered the observed polarization pattern and we have found that the radial component of the ambient pre-supernova magnetic field should be dominant on the length-scale of the present-day radius of SN1987A. The physical reasons for such a field are discussed.

astro-ph.HE↗

arXiv2022

Investigating particle acceleration dynamics in interpenetrating magnetized collisionless super-critical shocks

Colliding collisionless shocks appear in a great variety of astrophysical phenomena and are thought to be possible sources of particle acceleration in the Universe. We have previously investigated particle acceleration induced by single super-critical shocks (whose magnetosonic Mach number is higher than the critical value of 2.7) (Yao et al. 2021, 2022), as well as the collision of two sub-critical shocks (Fazzini et al. 2022). Here, we propose to make measurements of accelerated particles from interpenetrating super-critical shocks to observe the ''phase-locking effect'' (Fazzini et al. 2022) from such an event. This effect is predicted to significantly boost the energy spectrum of the energized ions compared to a single supercritical collisionless shock. We thus anticipate that the results obtained in the proposed experiment could have a significant impact on our understanding of one type of primary source (acceleration of thermal ions as opposed to secondary acceleration mechanisms of already energetic ions) of ion energization of particles in the Universe.

physics.plasm-ph↗

arXiv2022

Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A

Observations of the SNR Cassiopeia A (Cas A) show asymmetries in the reverse shock that cannot be explained by models describing a remnant expanding through a spherically symmetric wind of the progenitor star. We investigate whether a past interaction of Cas A with an asymmetric circumstellar shell can account for the observed asymmetries. We performed 3D MHD simulations that describe the remnant evolution from the SN to its interaction with a circumstellar shell. The initial conditions are provided by a 3D neutrino-driven SN model whose morphology resembles Cas A. We explored the parameter space of the shell, searching for a set of parameters able to produce reverse shock asymmetries at the age of 350 years analogous to those observed in Cas A. The interaction of the remnant with the shell can produce asymmetries resembling those observed in the reverse shock if the shell was asymmetric with the densest portion in the nearside to the northwest (NW). The reverse shock shows the following asymmetries at the age of Cas A: i) it moves inward in the observer frame in the NW region, while it moves outward in other regions; ii) the geometric center of the reverse shock is offset to the NW from the geometric center of the forward shock; iii) the reverse shock in the NW region has enhanced nonthermal emission because, there, the ejecta enter the reverse shock with a higher velocity (between 4000 and 7000 km/s) than in other regions (below 2000 km/s). The asymmetries observed in the reverse shock of Cas A can be interpreted as signatures of the interaction of the remnant with an asymmetric circumstellar shell that occurred between 180 and 240 years after the SN event. We suggest that the shell was, most likely, the result of a massive eruption from the progenitor star that occurred between $10^4$ and $10^5$ years prior to core-collapse. We estimate a total mass of the shell of the order 2 Msun.

astro-ph.HE↗

arXiv2022

High energy gamma-ray detection of supernova remnants in the Large Magellanic Cloud

We present the results of a cluster search in the gamma-ray sky images of the Large Magellanic Cloud (LMC) region by means of the Minimum Spanning Tree (MST) and DBSCAN algorithms, at energies higher than 6 and 10 GeV, using 12 years of Fermi-LAT data. Several significant clusters were found, the majority of which associated with previously known gamma-ray sources. We confirm our previous detection of the Supernova Remnants N 49B and N 63A and found new significant clusters associated with the SNRs N 49, N 186D and N 44. These sources are among the brightest X-ray remnants in the LMC and corresponds to core-collapse supernovae interacting with dense HII regions, indicating that an hadronic origin of high energy photons is the most likely process.

astro-ph.HE↗

arXiv2022

Particle energization in colliding subcritical collisionless shocks investigated in the laboratory

Colliding collisionless shocks appear in a great variety of astrophysical phenomena and are thought to be possible sources of particle acceleration in the Universe. To investigate the detailed dynamics of this phenomenon, we have performed a dedicated laboratory experiment. We have generated two counter-streaming subcritical collisionless magnetized shocks by irradiating two teflon (CF$_2$) targets with 100 J, 1 ns laser beams on the LULI2000 laser facility. The interaction region between the plasma flows was pre-filled with a low density background hydrogen plasma and initialized with an externally applied homogeneous magnetic field perpendicular to the shocks. We report here on measurements of the plasma density and temperature during the formation of the supercritical shocks, their transition to subcritical, and final interpenetration. We have also modeled the macroscopic evolution of the system via hydrodynamic simulations and the microphysics at play during the interaction via Particle-In-Cell simulations. The main goal was to understand what was the effect of the second shock on particle energization. We found that in the presence of two shocks the ambient ions reach energies around 1.5 times of the ones obtained with single shocks. Both the presence of the downstream zone of the second shock and of the downstream zone common for the two shocks play a role in the different energization: the characteristics of the perpendicular electric fields in the two areas allow, indeed, certain particles to keep being accelerated or to avoid being decelerated.

physics.plasm-ph↗

arXiv2022

Negative and Positive Feedback from a Supernova Remnant with SHREC: A detailed Study of the Shocked Gas in IC443

Supernova remnants (SNRs) contribute to regulate the star formation efficiency and evolution of galaxies. As they expand into the interstellar medium (ISM), they transfer vast amounts of energy and momentum that displace, compress and heat the surrounding material. Despite the extensive work in galaxy evolution models, it remains to be observationally validated to what extent the molecular ISM is affected by the interaction with SNRs. We use the first results of the ESO-ARO Public Spectroscopic Survey SHREC, to investigate the shock interaction between the SNR IC443 and the nearby molecular clump G. We use high sensitivity SiO(2-1) and H$^{13}$CO$^+$(1-0) maps obtained by SHREC together with SiO(1-0) observations obtained with the 40m telescope at the Yebes Observatory. We find that the bulk of the SiO emission is arising from the ongoing shock interaction between IC443 and clump G. The shocked gas shows a well ordered kinematic structure, with velocities blue-shifted with respect to the central velocity of the SNR, similar to what observed toward other SNR-cloud interaction sites. The shock compression enhances the molecular gas density, n(H$_2$), up to $>$10$^5$ cm$^{-3}$, a factor of >10 higher than the ambient gas density and similar to values required to ignite star formation. Finally, we estimate that up to 50\% of the momentum injected by IC443 is transferred to the interacting molecular material. Therefore the molecular ISM may represent an important momentum carrier in sites of SNR-cloud interactions.

astro-ph.GA↗

arXiv2021

Modeling the Remnants of Core-collapse Supernovae from Luminous Blue Variable stars

LBVs are massive evolved stars that suffer sporadic and violent mass-loss events. They have been proposed as the progenitors of some core-collapse SNe, but this idea is still debated due to the lack of direct evidence. Since SNRs can carry in their morphology the fingerprints of the progenitor stars as well as of the inhomogeneous CSM sculpted by the progenitors, the study of SNRs from LBVs could help to place core-collapse SNe in context with the evolution of massive stars. We investigate the physical, chemical and morphological properties of the remnants of SNe originating from LBVs, in order to search for signatures, revealing the nature of the progenitors, in the ejecta distribution and morphology of the remnants. As a template of LBVs, we considered the actual LBV candidate Gal 026.47+0.02. We selected a grid of models, which describe the evolution of a massive star with properties consistent with those of Gal 026.47+0.02 and its final fate as core-collapse SN. We developed a 3D HD model that follows the post-explosion evolution of the ejecta from the breakout of the shock wave at the stellar surface to the interaction of the SNR with a CSM characterized by two dense nested toroidal shells, parametrized in agreement with multi-wavelength observations of Gal 026.47+0.02. Our models show a strong interaction of the blast wave with the CSM which determines an important slowdown of the expansion of the ejecta in the equatorial plane where the two shells lay, determining a high degree of asymmetry in the remnant. After 10000 years of evolution the ejecta show an elongated shape forming a broad jet-like structure caused by the interaction with the shells and oriented along the axis of the toroidal shells.

astro-ph.SR↗

arXiv2021

Laboratory evidence for proton energization by collisionless shock surfing

Charged particles can be accelerated to high energies by collisionless shock waves in astrophysical environments, such as supernova remnants. By interacting with the magnetized ambient medium, these shocks can transfer energy to particles. Despite increasing efforts in the characterization of these shocks from satellite measurements at the Earth's bow shock and powerful numerical simulations, the underlying acceleration mechanism or a combination thereof is still widely debated. Here, we show that astrophysically relevant super-critical quasi-perpendicular magnetized collisionless shocks can be produced and characterized in the laboratory. We observe characteristics of super-criticality in the shock profile as well as the energization of protons picked up from the ambient gas to hundreds of keV. Kinetic simulations modelling the laboratory experiment identified shock surfing as the proton acceleration mechanism. Our observations not only provide the direct evidence of early stage ion energization by collisionless shocks, but they also highlight the role this particular mechanism plays in energizing ambient ions to feed further stages of acceleration. Furthermore, our results open the door to future laboratory experiments investigating the possible transition to other mechanisms, when increasing the magnetic field strength, or the effect induced shock front ripples could have on acceleration processes.

physics.plasm-ph↗

arXiv2021

Detailed characterization of laboratory magnetized super-critical collisionless shock and of the associated proton energization

Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of non-thermal particles and high-energy radiation. In the absence of particle collisions in the system, theoretical works show that the interaction of an expanding plasma with a pre-existing electromagnetic structure (as in our case) is able to induce energy dissipation and allow for shock formation. Shock formation can alternatively take place when two plasmas interact, through microscopic instabilities inducing electromagnetic fields which are able in turn to mediate energy dissipation and shock formation. Using our platform where we couple a fast-expanding plasma induced by high-power lasers (JLF/Titan at LLNL and LULI2000) with high-strength magnetic fields, we have investigated the generation of magnetized collisionless shock and the associated particle energization. We have characterized the shock to be collisionless and super-critical. We report here on measurements of the plasma density, temperature, the electromagnetic field structures, and particle energization in the experiments, under various conditions of ambient plasma and B-field. We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations. As a companion paper of \citet{yao2020laboratory}, here we show additional results of the experiments and simulations, providing more information to reproduce them and demonstrating the robustness of our interpreted proton energization mechanism to be shock surfing acceleration.

physics.plasm-ph↗

arXiv2021

Modeling the mixed-morphology supernova remnant IC 443. Origin of its complex morphology and X-ray emission

The morphology and the distribution of material observed in SNRs reflect the interaction of the SN blast wave with the ambient environment, the physical processes associated with the SN explosion and the internal structure of the progenitor star. IC 443 is a MM SNR located in a quite complex environment: it interacts with a molecular cloud in the NW and SE areas and with an atomic cloud in the NE. In this work we aim at investigating the origin of the complex morphology and multi-thermal X-ray emission observed in SNR IC 443, through the study of the effect of the inhomogeneous ambient medium in shaping its observed structure, and the exploration of the main parameters characterizing the remnant. We developed a 3D HD model for IC 443, which describes the interaction of the SNR with the environment, parametrized in agreement with the results of the multi-wavelength data analysis. We performed an ample exploration of the parameter space describing the initial blast wave and the environment, and the surrounding clouds. From the simulations, we synthesized the X-ray emission maps and spectra and compared them with actual X-ray data collected by XMM-Newton. Our model explains the origin of the complex X-ray morphology of SNR IC 443 in a natural way, being able to reproduce, for the first time, most of the observed features, including the centrally-peaked X-ray morphology (characteristic of MM SNRs) when considering the origin of the explosion at the position where the PWN CXOU J061705.3+222127 was at the time of the explosion. In the model which best reproduces the observations, the mass of the ejecta and the energy of the explosion are $\sim 7 M_\odot$ and $\sim10^{51}$ erg, respectively. From the exploration of the parameter space, we found that the density of the clouds is $n>300$ cm$^{-3}$ and that the age of SNR IC 443 is $\sim8000$ yr.

astro-ph.HE↗

arXiv2020

Linking core-collapse supernova explosions to supernova remnants through 3D MHD modeling

The structure and morphology of supernova remnants (SNRs) reflect the properties of the parent supernovae (SNe) and the characteristics of the inhomogeneous environments through which the remnants expand. Linking the morphology of SNRs to anisotropies developed in their parent SNe can be essential to obtain key information on many aspects of the explosion processes associated with SNe. Nowadays, our capability to study the SN-SNR connection has been largely improved thanks to multi-dimensional models describing the long-term evolution from the SN to the SNR as well as to observational data of growing quality and quantity across the electromagnetic spectrum which allow to constrain the models. Here we used the numerical resources obtained in the framework of the "Accordo Quadro INAF-CINECA (2017)" together with a CINECA ISCRA Award N.HP10BARP6Y to describe the full evolution of a SNR from the core-collapse to the full-fledged SNR at the age of 2000 years. Our simulations were compared with observations of SNR Cassiopeia A (Cas A) at the age of $\sim 350$~years. Thanks to these simulations we were able to link the physical, chemical and morphological properties of a SNR to the physical processes governing the complex phases of the SN explosion.

astro-ph.HE↗

arXiv2020

Modeling particle acceleration and non-thermal emission in supernova remnants

According to the most popular model for the origin of cosmic rays (CRs), supernova remnants (SNRs) are the site where CRs are accelerated. Observations across the electromagnetic spectrum support this picture through the detection of non-thermal emission that is compatible with being synchrotron or inverse Compton radiation from high energy electrons, or pion decay due to proton-proton interactions. These observations of growing quantity and quality promise to unveil many aspects of CRs acceleration and require more and more accurate tools for their interpretation. Here, we show how multi-dimensional MHD models of SNRs, including the effects on shock dynamics due to back-reaction of accelerated CRs and the synthesis of non-thermal emission, turned out to be very useful to investigate the signatures of CRs acceleration and to put constraints on the acceleration mechanism of high energy particles. These models have been used to interpret accurately observations of SNRs in various bands (radio, X-ray and $γ$-ray) and to extract from them key information about CRs acceleration.

astro-ph.HE↗

arXiv2020

The fully developed remnant of a neutrino-driven supernova: Evolution of ejecta structure and asymmetries in SNR Cassiopeia A

Abridged. We aim at exploring to which extent the remnant keeps memory of the asymmetries that develop stochastically in the neutrino-heating layer due to hydrodynamic instabilities (e.g., convective overturn and the standing accretion shock instability) during the first second after core bounce. We coupled a 3D HD model of a neutrino-driven SN explosion with 3D MHD/HD simulations of the remnant formation. The simulations cover 2000 years of expansion and include all physical processes relevant to describe the complexities in the SN evolution and the subsequent interaction of the stellar debris with the wind of the progenitor star. The interaction of large-scale asymmetries left from the earliest phases of the explosion with the reverse shock produces, at the age of $\approx 350$~years, an ejecta structure and a remnant morphology which are remarkably similar to those observed in Cas A. Small-scale structures in the large-scale Fe-rich plumes created during the initial stages of the SN, combined with HD instabilities that develop after the passage of the reverse shock, naturally produce a pattern of ring- and crown-like structures of shocked ejecta. The consequence is a spatial inversion of the ejecta layers with Si-rich ejecta being physically interior to Fe-rich ejecta. The full-fledged remnant shows voids and cavities in the innermost unshocked ejecta resulting from the expansion of Fe-rich plumes and their inflation due to the decay of radioactive species. The asymmetric distributions of $^{44}$Ti and $^{56}$Fe and their abundance ratio are both compatible with those inferred from high-energy observations of Chandra and NuSTAR. The main asymmetries observed in the ejecta distribution of Cas A can be explained by the interaction of the reverse shock with the large-scale asymmetries that developed from stochastic processes that originate during the first seconds of the SN blast.

astro-ph.HE↗

arXiv2019

Hydrodynamic simulations unravel the progenitor-supernova-remnant connection in SN 1987A

(Abridged) We aim at linking the dynamical and radiative properties of the remnant of SN 1987A to the geometrical and physical characteristics of the parent aspherical SN explosion and to the internal structure of its progenitor star. We performed 3D hydrodynamic simulations which describe the long-term evolution of SN 1987A from the onset of the SN to the full-fledged remnant at the age of 50 years, accounting for the pre-SN structure of the progenitor star. The simulations include all physical processes relevant for the complex phases of SN evolution and for the interaction of the SNR with the highly inhomogeneous ambient environment around SN 1987A. From the simulations, we synthesize observables to be compared with observations. By comparing the model results with observations, we constrained the initial SN anisotropy causing Doppler shifts observed in emission lines of heavy elements from ejecta, and leading to the remnant evolution observed in the X-ray band in the last 30 years. In particular, we found that the high mixing of ejecta unveiled by high redshifts and broadenings of [FeII] and $^{44}$Ti lines require a highly asymmetric SN explosion channeling a significant fraction of energy along an axis almost lying in the plane of the central equatorial ring around SN 1987A, roughly along the line-of-sight but with an offset of 40 deg, with the lobe propagating away from the observer slightly more energetic than the other. We found unambiguously that the observed distribution of ejecta and the dynamical and radiative properties of the SNR can be best reproduced if the structure of the progenitor star was that of a blue supergiant resulted from the merging of two massive stars.

astro-ph.HE↗

arXiv2019

A stellar flare-coronal mass ejection event revealed by X-ray plasma motions

Coronal mass ejections (CMEs), often associated with flares, are the most powerful magnetic phenomena occurring on the Sun. Stars show magnetic activity levels up to 10^4 times higher, and CME effects on stellar physics and circumstellar environments are predicted to be significant. However, stellar CMEs remain observationally unexplored. Using time-resolved high-resolution X-ray spectroscopy of a stellar flare on the active star HR 9024 observed with Chandra/HETGS, we distinctly detected Doppler shifts in S XVI, Si XIV, and Mg XII lines that indicate upward and downward motions of hot plasmas (~10-25 MK) within the flaring loop, with velocity v~100-400 km/s, in agreement with a model of flaring magnetic tube. Most notably, we also detected a later blueshift in the O VIII line which reveals an upward motion, with v=90+/-30 km/s, of cool plasma (~4 MK), that we ascribe to a CME coupled to the flare. From this evidence we were able to derive a CME mass of 1x10^21 g and a CME kinetic energy of 5x10^34 erg. These values provide clues in the extrapolation of the solar case to higher activity levels, suggesting that CMEs could indeed be a major cause of mass and angular momentum loss.

astro-ph.SR↗

arXiv2018

3D MHD modeling of the expanding remnant of SN 1987A. Role of magnetic field and non-thermal radio emission

Aims. We investigate the role played by a pre-supernova (SN) ambient magnetic field on the dynamics of the expanding remnant of SN 1987A and the origin and evolution of the radio emission from the remnant, in particular, during the interaction of the blast wave with the nebula surrounding the SN. Methods. We model the evolution of SN 1987A from the breakout of the shock wave at the stellar surface to the expansion of its remnant through the surrounding nebula by 3D MHD simulations. The model considers the radiative cooling, the deviations from equilibrium of ionization, the deviation from temperature-equilibration between electrons and ions, and a plausible configuration of the pre-SN ambient magnetic field. From the simulations, we synthesize both thermal X-ray and non-thermal radio emission and compare the model results with observations. Results. The presence of an ambient magnetic field reduces the erosion and fragmentation of the dense equatorial ring after the impact of the SN blast wave. As a result, the ring survives the passage of the blast, at least, during the time covered by the simulations (40 years). Our model is able to reproduce the morphology and lightcurves of SN 1987A in both X-ray and radio bands. The model reproduces the observed radio emission if the flux originating from the reverse shock is heavily suppressed. In this case, the radio emission originates mostly from the forward shock traveling through the H II region. Possible mechanisms for the suppression of emission from the reverse shock are investigated. We find that synchrotron self-absorption and free-free absorption have negligible effects on the emission during the interaction with the nebula. We suggest that the emission from the reverse shock at radio frequencies might be limited by highly magnetized ejecta.

astro-ph.HE↗

arXiv2018

Investigating the Structure of Vela X

Vela X is the prototypical example of a pulsar wind nebula whose morphology and detailed structure have been affected by the interaction with the reverse shock of its host supernova remnant. The resulting complex of filamentary structure and mixed-in ejecta embedded in a nebula that is offset from the pulsar provides the best example we have of this middle-age state that characterizes a significant fraction of composite SNRs, and perhaps all of the large-diameter PWNe seen as TeV sources. Here we report on an XMM-Newton Large Project study of Vela X, supplemented by additional Chandra observations. Through broad spectral modeling as well as detailed spectral investigations of discrete emission regions, we confirm previous studies that report evidence for ejecta material within Vela X, and show that equivalent width variations of O VII and O VIII are consistent with temperature maps within the PWN that show low-temperature regions where the projected SNR emission appears to dominate emission from the ejecta. We identify spectral variations in the nonthermal emission, with hard emission being concentrated near the pulsar. We carry out investigations of the Vela X "cocoon" structure and, with hydrodynamical simulations, show that its overall properties are consistent with structures formed in the late-phase evolution of a composite SNR expanding into a surrounding medium with a density gradient, with ejecta material being swept beyond the pulsar and compressed into an elongated structure in the direction opposite the high external density.

astro-ph.HE↗