Articles publicats en revistes (Física Quàntica i Astrofísica)

URI permanent per a aquesta col·leccióhttps://hdl.handle.net/2445/7504

Estadístiques

Examinar

Mostrant 1 - 20 de 2952

L-shell X-ray production cross-sections for Mo by proton impact
(Royal Society of Chemistry, 2019-01-01) Pérez, Pablo D.; Rodríguez, Tabatha P.; Trincavelli, Jorge C.; Fernández Varea, José María; Suárez, Sergio G.
Total L and Li subshell X-ray production cross-sections were determined experimentally for Mo by proton impact. The thick-target method was used, and the proton energies ranged from 200 keV to 3 MeV. The recorded X-ray spectra were fitted using novel open software for PIXE semi-quantitative analysis that takes into account X-ray emission, absorption and detection. K-shell X-ray production cross-sections of Ti and Cu samples were used to normalize our results for Mo. The measured Mo L X-ray production cross-sections are in excellent agreement with the predictions of the ECPSSR theory. The sensitivity of the theoretical L shell and Li subshell X-ray production cross-sections to the adopted fluorescence yields and Coster-Kronig coefficients was also studied.
A low-cost small-size commercial PIN photodiode: II. Comparison of measurements with monoenergetic electrons to analytical expressions and Monte Carlo simulations
(Elsevier Ltd., 2021-01-01) Mangiarotti, Alessio; Petri, Anna R.; Malafronte, Alexandre A.; Gonçalves, Josemary A.C.; Barros, Suelen F.; Bueno, C.C.; Fernández Varea, José María; Maidana, Nora L.; Martins, Marcos N.; Vanin, Vito R.
Commercial PIN photodiodes, repurposed as particle detectors, have received a lot of attention along the past
decades because they can offer a low-cost solution suitable for several applications. The BPX-65 photodiode has
been chosen because of its interesting features for measuring electrons in a harsh radiation environment close to
the beam of an accelerator. Its electrical characterisation and its application to photon spectrometry have been
presented in the companion paper I. Here, its response function (RF) to electrons is investigated using the beam
from an electron accelerator with a small energy spread. The empirical expressions for the RF available in the
literature have been improved, simplified, and combined to obtain a final form with 7 free parameters: 4 nonlinear
and 3 linear. A special fitting procedure, which takes advantage of the presence of the linear parameters,
is described. The behaviour of these parameters with beam energy and bias is investigated to uncover the
physical origin of the three components included in the proposed RF. The interpretation of the features of the
spectra is confirmed by Monte Carlo simulations carried out employing the general-purpose PENELOPE/penEasy
package. To take into account the charge-collection properties of the device, a simple model has been implemented
and is compared to data. It has then been possible to estimate the thickness of the partially dead layer
from the experiment.
RADIAL: A Fortran subroutine package for the solution of the radial Schrödinger and Dirac wave equations
(Elsevier B.V., 2019-01-01) Salvat Gavaldà, Francesc; Fernández Varea, José María
The Fortran subroutine package RADIAL for the numerical solution of the Schrödinger and Dirac wave equations of electrons in central potentials V(r) is described. The considered potentials are such that the function V(r) ≡ rV (r) is finite for all r and tends to constant values when r → 0 and r → ∞. This includes finite-range potentials as well as combinations of Coulomb and finite-range potentials. The function V(r) used in the numerical calculation is the natural cubic spline that interpolates a table of values provided by the user. The radial wave equations are solved by using piecewise exact power series expansions of the radial functions, which are summed up to the prescribed accuracy so that truncation errors can be completely avoided. The RADIAL subroutines compute radial wave functions, eigenvalues for bound states and phase shifts for free states. Specific subroutines are also provided for computing the radial functions and phase shifts for free states of complex optical potentials having a finite-range absorptive imaginary part. The solution subroutines are accompanied by example main programs, as well as with specific programs that perform calculations relevant in atomic, nuclear, and radiation physics (the self-consistent solution of the Dirac-Hartee-Fock-Slater equations for neutral atoms and positive ions, and the calculation of cross sections for elastic scattering of high-energy electrons and positrons by atoms and of nucleons by nuclei). The distribution package includes a detailed manual with a description of the basic physics and the mathematical formulas implemented in the subroutines.
On the relativistic impulse approximation for the calculation of Compton scattering cross sections and photon interaction coefficients used in kV dosimetry
(ART AMB B, 2020-01-01) Wang, X.J.; Miguel, Beatriz; Seuntjens, J.; Fernández Varea, José María
We calculate differential and integrated cross sections for the Compton interaction as well as mass
attenuation (μC/ρ), mass energy-transfer (μC
tr/ρ), and mass energy-absorption (μen/ρ)
coefficients, within the relativistic impulse approximation (RIA) using Compton profiles (CPs)
obtained from unrestricted Hartree–Fock electron densities. We investigate the impact of using
molecular as opposed to atomic CPs on dosimetric photon interaction coefficients for air, water
and graphite, and compare our cross sections to the simpler Waller–Hartree (WH) and
Klein–Nishina (KN) formalisms. We find that differences in μC/ρ and μC
tr/ρ resulting from the
choice of CPs within the RIA are small relative to the differences between the RIA, WH, and KN
calculations. Surprisingly, although the WH binding corrections seem accurate when considering
μC/ρ, there are significant discrepancies between the WH and RIA results when we look at μC
tr/ρ.
The WH theory can differ substantially from the predictions of KN and the RIA in the tens of keV
range (e.g. 6%–10% at 20 keV), when Compton scattering becomes the dominant interaction
mechanism. For lower energies, the disagreement further grows to about one order of magnitude
at 1 keV. However, since the photoelectric effect transfers more energy than the Compton
interaction in the tens of keV range and below, the differences in the total μen/ρ values resulting
from the choice of Compton models (KN, WH, or RIA) are not larger than 0.4%, and the
differences between WH and the other two theories are no longer prominent.
Electronic stopping power of diamond for electrons and positrons
(ART AMB B, 2021-01-01) Fernández Varea, José María; Górka, Bartosz; Nilsson, Bo
We assess a new data set of mass electronic stopping powers of diamond for electrons and positrons.
To this end, an optical energy-loss function (OELF) for this material is generated from available
experimental dielectric properties of the valence band and photoabsorption mass attenuation
coefficients, supplemented with a Drude-type analytical expression to interpolate at intermediate
energies. From this synthetic OELF, a mean excitation energy equal to (88.5±2.0) eV is extracted and
the density-effect correction is evaluated using Fano’s simplified method. These quantities then allow
calculating the mass electronic stopping power of diamond for electrons and positrons by means of
the relativistic Bethe formula. The present results for 1 keV–1 GeV electrons in diamond are 0.9%–
3.3% smaller than those corresponding to graphite as tabulated in ICRU Report 90.
Electronic stopping power of diamond for electrons and positrons
(ART AMB B, 2021-01-01) Fernández Varea, José María; Górka, Bartosz; Nilsson, Bo
We assess a new data set of mass electronic stopping powers of diamond for electrons and positrons.
To this end, an optical energy-loss function (OELF) for this material is generated from available
experimental dielectric properties of the valence band and photoabsorption mass attenuation
coefficients, supplemented with a Drude-type analytical expression to interpolate at intermediate
energies. From this synthetic OELF, a mean excitation energy equal to (88.5±2.0) eV is extracted and
the density-effect correction is evaluated using Fano’s simplified method. These quantities then allow
calculating the mass electronic stopping power of diamond for electrons and positrons by means of
the relativistic Bethe formula. The present results for 1 keV–1 GeV electrons in diamond are 0.9%–
3.3% smaller than those corresponding to graphite as tabulated in ICRU Report 90.
Young starless cores embedded in the magnetically dominated Pipe nebula. II. Extended dataset
(Institute of Physics (IOP), 2012) Frau, Pau; Girart, Josep Miquel ; Beltrán Sorolla, Maria Teresa; Padovani, Marco; Busquet Rico, Gemma; Morata, Oscar; Masqué Saumell, Josep Maria; Alves, Felipe O.; Sánchez Monge, Álvaro; Franco, Gabriel Armando Pellegatti; Estalella, Robert
The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is therefore a good laboratory to study the earliest stages of the star formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30 m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived an A(V) to N-H2 factor of (1.27 +/- 0.12) x 10(-21) mag cm(2) and a background visual extinction of similar to 6.7 mag possibly arising from the cloud material. We derived an average core diameter of similar to 0.08 pc, density of similar to 10(5) cm(-3), and mass of similar to 1.7 M-circle dot. Several trends seem to exist related to increasing core density: (1) the diameter seems to shrink, (2) the mass seems to increase, and (3) the chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large-scale magnetic fields seem to play a secondary role in shaping the cores. We also used the IRAM 30 m telescope to extend the previous molecular survey at 1 and 3 mm of early- and late-time molecules toward the same five new Pipe nebula starless cores, and analyzed the normalized intensities of the detected molecular transitions. We confirmed the chemical differentiation toward the sample and increased the number of molecular transitions of the "diffuse" (e.g., the " ubiquitous" CO, C2H, and CS), "oxo-sulfurated" (e.g., SO and CH3OH), and "deuterated" (e.g., N2H+, CN, and HCN) starless core groups. The chemically defined core groups seem to be related to different evolutionary stages: "diffuse" cores present the cloud chemistry and are less dense, while "deuterated" cores are the densest and present a chemistry typical of evolved dense cores. "Oxo-sulfurated" cores might be in a transitional stage exhibiting intermediate properties and a very characteristic chemistry.
MeerKAT view of Hickson Compact Groups. I. Data description and release
(EDP Sciences, 2025-04) Bosma, A.; Athanassoula, E.; Józsa, G.I.G.; Jarrett, T.H.; Xu, C.K.; Román, J.; Labadie, X.; Cabanillas de la Casa, C.; Borthakur, S.; Wang, J.; García-Benito, R.; del Olmo, A.; Perea, J.D.; Wiegert, T.; Yun, M.; Ianjamasimanana, R.; Verdes-Montenegro, L.; Sorgho, A.; Hess, K.M.; Jones, M.G.; Cannon, J.M.; Solanes, José M. (José María); Cluver, M.E.; Moldón, J.; Namumba ,B.; Garrido, J.; Sánchez-Expósito, S.
Abstract Context. Hickson Compact Groups (HCGs) are dense gravitationally bound collections of four to ten galaxies and are ideal for studying gas and star formation quenching processes. Aims. We aim to understand the transition of HCGs from possessing complex H I tidal structures (so-called phase 2 groups) to a phase where galaxies have lost most or all of their H I (phase 3). We also seek to detect diffuse H I gas that was previously missed by the Very Large Array (VLA). Methods. We observed three phase 2 and three phase 3 HCGs with MeerKAT and reduced the data using the Containerized Automated Radio Astronomy Calibration (CARACal) pipeline. We produced data cubes, moment maps, and integrated spectra, and we compared our findings with previous VLA and Green Bank Telescope observations. Results. Compared with previous VLA observations, MeerKAT reveals much more extended tidal features in phase 2 and some new high surface brightness features in phase 3 groups. However, no diffuse H I component was found in phase 3 groups. We also detected many surrounding galaxies for both phase 2 and phase 3 groups, most of which are normal disc galaxies. Conclusions. The difference between phase 2 and phase 3 groups is still substantial, supporting the previous finding that the transition between the two phases must be abrupt.
Fully comprehensive diagnostic of galaxy activity using principal componentsof visible spectra: implementation on nearby S0s
(Royal Astronomical Society, 2025-02) Tous Mayol, Josep Lluís; Solanes, José M. (José María); Perea Duarte, Jaime D.
We introduce a novel galaxy classification methodology based on the visible spectra of a sample of over 68 000 nearby (z≤0.1) Sloan Digital Sky Survey lenticular (S0) galaxies. Unlike traditional diagnostic diagrams, which rely on a limited set of emission lines and class dividers to identify ionizing sources, our approach provides a comprehensive framework for characterizing galaxies regardless of their activity level. By projecting galaxies into the 2D latent space defined by the first three principal components (PCs) of their entire visible spectra, our method remains robust even when data from individual emission lines are missing. We employ Gaussian kernel density estimates of the classical Baldwin-Phillips-Terlevich (BPT) activity classes in the new classification subspace, adjusted according to their relative abundance in our S0 sample, to generate probability maps for star-forming, Seyfert, composite, and low-ionization nuclear emission-line region (LINER) galaxies. These maps closely mirror the canonical distribution of BPT classes shown by the entire galaxy population, demonstrating that our PC-based taxonomy effectively predicts the dominant ionizing mechanisms through a probabilistic approach that provides a realistic reflection of galaxy activity and allows for refined class membership. Our analysis further reveals that flux-limited BPT-like diagrams are inherently biased against composite and star-forming galaxies due to their weaker [O III] emission. Besides, it suggests that although most low-activity galaxies excluded from these diagnostics exhibit visual spectra with LINER-like characteristics, their remaining activity is likely driven by mechanisms unrelated to either star formation or supermassive black hole accretion. A machine-readable catalogue listing BPT-class probabilities for the galaxies analysed is publicly released with this article.
Growth of Ex-situ Diffuse Intergalactic Light in Simulated Galaxy Groups
(EDP Sciences, 2025-03) Bilata-Woldeyes, Betelehem; Perea Duarte, Jaime D.; Solanes, José M. (José María)
Context. Deep surface photometry has revealed the presence of a faint and diffuse baryonic component permeating the intragroup space in a significant fraction of galaxy groups. This intragroup light (IGL) is primarily formed by stars that are removed from their host galaxies through gravitational interactions and now drift freely, unbound to any particular galaxy. Aims. We conducted a detailed analysis to investigate how various physical parameters of galaxy groups influence the formation of ex situ IGL during the earliest stages of group assembly, and to explore their correlations with the mass and fractional abundance of this component. Additionally, we evaluated the potential of the IGL as a luminous tracer of the total mass distribution in galaxy groups, with a particular focus on systems that are far from dynamically relaxed. Methods. We used controlled numerical simulations of 100 low-mass galaxy groups spanning a range of masses and numbers of constituent galaxies to track the formation and evolution of IGL during the earliest pre-virialization stages of these systems. Results. We show that the IGL typically begins to form in significant amounts after the turnaround epoch, which in our simulated groups occurs at a median redshift (z̄_ta) of ∼0.85, increasing steadily thereafter. We observe a sub-linear relationship between the masses of this component and the brightest group galaxy, which indicates intertwined formation histories but differing growth rates. This suggests that other group members may also significantly contribute to the diffuse light. Additionally, we observe indications that IGL formation is enhanced in groups with lower internal velocity dispersions, which suggests that gravitational interactions between member galaxies become more efficient when their relative velocities are reduced. For two-thirds of our groups, the radial surface density profiles of the total and IGL mass are significantly aligned, with fractional discrepancies below 25%. This supports the notion that this diffuse and faint baryonic component serves as a reliable tracer of the total gravitational potential in galaxy aggregations, regardless of their dynamical state. However, the results also indicate that the degree of similarity depends on the viewing direction.
MeerKAT view of Hickson Compact Groups. II. Deficiency in the core andsurrounding regions
(EDP Sciences, 2025-04-18) Jarrett, T.H.; Namumba, B.; Pérez, E.; Román, J.; Smirnov, O.; Yun, M.; Cannon, J.M.; Bosma, A.; Athanassoula, E.; del Olmo, A.; Perea, J.D.; Moldón, J.; Wiegert, T.; Sánchez-Expósito, S.; Garrido, J.; García-Benito, R.; Sorgho, A.; Verdes-Montenegro, L.; Ianjamasimanana, R.; Hess, K.M.; Jones, M.G.; Korsaga, M.; Wang, J.; Lin, X.; Solanes, José M. (José María); Cluver, M.E.; Józsa, G.I.G.; Borthakur, S.
Abstract Context. Hickson compact groups (HCGs) offer an ideal environment for investigating galaxy transformation as a result of interactions. It has been established that the evolutionary sequence of HCGs is marked by an intermediate stage characterised by a substantial amount of H I in their intragroup medium (IGrM) in the form of tidal tails and bridges (phase 2), rapidly followed by a final stage in which no IGrM gas is found and i which their member galaxies are highly H I deficient (phase 3). Aims. Despite numerous single-dish and interferometric H I studies on the HCGs, a clear H I picture of the groups within their large-scale environment still remains to be uncovered. Taking advantage of MeerKAT’s high column density sensitivity and large field of view, we aim to investigate the rapid transformation of HCGs from the intermediate to late phases, and establish a picture of their gas content variations in the context of their large-scale environments. Methods. We performed MeerKAT observations of six HCGs that were selected to represent the intermediate and late phases of the proposed evolutionary sequence. Combining the H I observations with data from recent wide-field optical surveys, we evaluated the H I deficiencies of galaxies in a ∼30′ radius of the HCGs. Results. We find that galaxies surrounding both phases exhibit similar distributions in their gas content. Similarly, galaxies making up the cores of phase 2 HCGs are comparable to their neighbours in terms of H I deficiencies. However, phase 3 groups are over an order of magnitude more deficient than their surroundings, supporting previous findings that late-phase HCG galaxies are more evolved than their large-scale environments.
The local universe in the era of large surveys. I. Spectral classification of S0 galaxies
(Royal Astronomical Society, 2020-05) Tous Mayol, Josep Lluís; Solanes, José M. (José María); Perea Duarte, Jaime D.
This is the first paper in a series devoted to review the main properties of galaxies designated S0 in the Hubble classification system. Our aim is to gather abundant and, above all, robust information on the most relevant physical parameters of this poorly-understood morphological type and their possible dependence on the environment that could later be used to assess their possible formation channel(s). The adopted approach combines the characterisation of the fundamental features of the optical spectra of 68,043 S0 with heliocentric z≲0.1 with the exploration of a comprehensive set of their global attributes. A principal component analysis is used to reduce the huge number of dimensions of the spectral data to a low-dimensional space facilitating a bias-free machine-learning-based classification of the galaxies. This procedure has revealed that objects bearing the S0 designation consist, despite their similar morphology, of two separate sub-populations with statistically inconsistent physical properties. Compared to the absorption-dominated S0, those with significant nebular emission are, on average, somewhat less massive, more luminous with less concentrated light profiles, have a younger, bluer and metal-poorer stellar component, and avoid high-galaxy-density regions. Noteworthy is the fact that the majority of members of this latter class, which accounts for at least a quarter of the local S0 population, show star formation rates and spectral characteristics entirely similar to those seen in late spirals. Our findings suggest that star-forming S0 might be less rare than hitherto believed and raise the interesting possibility of identifying them with plausible progenitors of their quiescent counterparts.
The local Universe in the era of large surveys. II. Multi-wavelength characterisation of activity in S0 galaxies
(Royal Astronomical Society, 2022-03) Jiménez Palau, Cristina; Solanes, José M. (José María); Perea Duarte, Jaime D.; del Olmo, A.; Tous Mayol, Josep Lluís
This is the second paper in a series using data from about 56,000 S0 galaxies of the local Universe (z < 0.1) retrieved from the NSA catalogue. It builds on the outcomes of the previous work, which introduced a new classification scheme for these objects based on the principal component analysis (PCA) of their optical spectrum and its projections on to the first two eigenvectors (the PC1-PC2 diagram). We provide an exhaustive characterization of the activity of present-day S0s throughout both the broad-band PC1-PC2 and narrow-line BPT/WHAN spectral classifiers, contrasting the different types of activity classes they define, and present an alternative diagram that exploits the concordance between WHAN and PCA demarcations. The analysis is extended to the mid-infrared, radio and X-ray wavelengths by crossmatching our core sample with data from the WISE, FIRST, XMM-Newton, and Chandra surveys. This has allowed us to carry out a thorough comparison of the most important activity diagnostics in the literature over different wavebands, discuss their similarities and differences, and explore the connections between them and with parameters related to star formation and black hole accretion. Among the results obtained, we highlight the finding of evidence that nebular emission from S0-Seyfert and LINER systems that are radio and X-ray emitters is not driven by star birth, while it cannot be discarded that for a number of the members of the latter class the dominant ionising radiation comes from post-AGB stars. These and other outcomes from the present work should be transferable to other morphologies.
The origin of star-forming rings in S0 galaxies
(Institute of Physics (IOP), 2023-01) Tous Mayol, Josep Lluís; Domínguez-Sánchez, H.; Solanes, José M. (José María); Perea Duarte, Jaime D.
Spatially resolved IFS maps in a sample of 532 S0 galaxies from the MaNGA survey have unveiled the existence of inner rings (⟨R⟩∼1Re) betraying ongoing star formation in a number of these objects. Activity gradients averaged over bins of galactocentric radius up to ∼1.5Re have been measured in the subspace defined by the first two principal components of the optical spectra of these galaxies. We find that the gradients sign is closely related to the presence of such rings in the spectral maps, which are specially conspicuous in the equivalent width of the Hα emission line, EW(Hα), with a fractional abundance ¿21-34%¿ notably larger than that inferred from optical images. While the numbers of S0s with positive, negative, and flat activity gradients are comparable, star-forming rings are largely found in objects for which quenching proceeds from the inside-out, in good agreement with predictions from cosmological simulations studying S0 buildup. Assessment of these ringed structures indicates that their frequency increases with the mass of their hosts, that they have shorter lifetimes in galaxies with ongoing star formation, that they may feed on gas from the disks, and that the local environment does not play a relevant role in their formation. We conclude that the presence of inner rings in the EW(Hα) is a common phenomenon in fully formed S0s, possibly associated with annular disk resonances driven by weakly disruptive mergers preferentially involving a relatively massive primary galaxy and a tiny satellite strongly bound to the former.
Tracing the evolution of the brightest galaxies and diffuse light in galaxy groups
(EDP Sciences, 2025-12) Bilata-Woldeyes, Betelehem; Perea Duarte, Jaime D.; Solanes, José M. (José María)
We present the second study based on a suite of 100 cosmologically motivated, controlled N-body simulations designed to advance our understanding of the role of purely gravitational dynamics in the early formation of low-mass galaxy groups (∼1–5 × 1013 M⊙). In this work, we investigate the temporal evolution of key indicators of dynamical relaxation, with a particular emphasis on the secular growth of the diffuse intragroup light (IGL), the four major group galaxies, and the mass distributions of their progenitors. We also assess the diagnostic power of several magnitude gaps between top-ranked galaxies as proxies for dynamical age. As in our previous study, we compare the outcomes from three group classes defined by the number of the brightest group galaxies (BGGs) present at the end of the simulations: single-, double-, and non-BGG systems. We find that the early assembly of galaxy groups is consistent with a stochastic Poisson process at an approximately constant merger rate. Various dynamical diagnostics, including galaxy pairwise separations, velocity dispersions, and the offset of the first-ranked galaxy from the group barycentre, indicate that single-BGG groups evolve more rapidly towards virialisation than double- and (especially) non-BGG systems. We further find that first-ranked group members and the IGL, despite their intertwined origins, follow distinct growth histories, with the IGL assembled from a more numerous and systematically lower mass population than the central object. This distinction is particularly pronounced in non-BGG systems, where about one-third of the IGL originates from small galaxies, each contributing less than 5% to this component. Among the tested magnitude gaps, the difference between the first- and fourth-ranked galaxies, Δℳ4−1, is proven to be a more robust indicator of dynamical age for low-mass groups than the conventional Δℳ2−1 gap. The Δℳ5−1 and Δℳ6−1 gaps also perform well and might be preferable in certain contexts.
The distribution of lenticular galaxies in the phase space of present-day galaxy cluster regions
(EDP Sciences, 2025-05) Gort, Mathias; Tous Mayol, Josep Lluís; Solanes, José M. (José María)
Lenticular (S0) galaxies are ubiquitous in both high- and low-density environments where diverse evolutionary mechanisms operate. Consequently, studying their distribution and properties across both the dense, virialized cluster cores and their sparser surrounding secondary infall regions can provide key insights into the still-debated processes driving their evolution. In this work, we investigated the environmental impact of cluster regions on the evolution of present-day S0 galaxies, focusing on their distinct quiescent and star-forming (SF) subpopulations. We selected a sample of nearby cluster regions by crossmatching optical and X-ray data and extract a subset of 14 systems with maximally relaxed cores by applying strict virialization and substructure tests. A projected phase space (PPS) diagram was then generated from the stack of maximally relaxed clusters up to 3 virial radii to assess the locations of quiescent and SF S0s and their cluster infall histories. Additionally, we compared the radial line-of-sight velocity dispersion (VDLOS) and specific star-formation rate (SSFR) profiles for the different S0 subpopulations, using other Hubble types as benchmarks. Our study shows that quiescent S0s, the dominant class in the entire cluster region, concentrate preferentially at low radii in the PPS diagram, while their SF counterparts are more abundant in the outskirts. Despite this segregation, quiescent and SF S0s exhibit similar VDLOS profiles in the dynamically relaxed cluster core –indicating an advanced stage of dynamical relaxation–, but that resemble those of late-type galaxies beyond the virial radius. This finding, combined with the distinct PPS distributions of both S0 subpopulations, which lead to mean infall times ∼1 Gyr longer for quiescent S0s but that are shorter than those expected for ancient infallers, suggests that a substantial fraction of S0s present in the core region arrive via secondary infall. We also find evidence in the radial SSFR profiles that star formation in S0s begins to decline well beyond the virialized core, likely due to preprocessing in infalling groups. Overall, our results support a delayed-then-rapid quenching scenario for SF S0s in cluster regions, where their centrally concentrated star formation persists for an extended period before abruptly ending (≲0.1 Gyr) after their first pericenter passage.
Time-resolved solvation of alkali ions in superfluid helium nanodroplets: Theoretical simulationof a pump–probe study
(American Institute of Physics (AIP), 2025-10-11) García-Alfonso, Ernesto; Barranco Gómez, Manuel; Pi Pericay, Martí; Halberstadt, Nadine
The solvation process of an alkali ion (Na+, K+, Rb+, and Cs+) inside a superfluid 4He2000 nanodroplet is investigated theoretically using liquid 4He time-dependent density functional theory at zero temperature. We simulate both steps of the pump–probe experiment conducted on Na+ [Albrechtsen et al., Nature 623, 319 (2023)], where the alkali atom residing at the droplet surface is ionized by the pump pulse and its solvation is probed by ionizing a central xenon atom and detecting the expulsed Na+Hen ions. Our results confirm the Poissonian model for the binding of the first five He atoms for the lighter Na+ and K+ alkalis, with a rate in good agreement with the more recent experimental results on Na+ [Albrechtsen et al., J. Chem. Phys. 162, 174309 (2025)]. For the probe step, we show that the ion takes several picoseconds to get out of the droplet. During this rather long time, the solvation structure around it is very hot and far from equilibrium, and it can gain or lose more He atoms. Surprisingly, analyzing the Na+ solvation structure energy reveals that it is not stable by itself during the first few picoseconds of the solvation process. After that, energy relaxation follows a Newton behavior, as found experimentally, but with a longer time delay, 5.0 ≤ t0 ≤ 6.5 ps vs 0.23 ± 0.06 ps, and characteristic time, 7.3 ≤ τ ≤ 16.5 ps vs 2.6 ± 0.4 ps. We conclude that the first instants of the solvation process are highly turbulent and that the solvation structure is stabilized only by the surrounding helium “solvent.”
Characterizing the Multiple Protostellar System VLA 1623-2417 with JWST, ALMA, and VLA: Outflow Origins, Dust Growth, and an Unsettled Disk
(Institute of Physics (IOP), 2025-03) Forbrich, Jan; Girart, Josep M.; Hoare, Melvin G.; Hernández Garnica, Ricardo; Jiménez-Serra, Izaskun; Loinard, Laurent; Ordóñez-Toro, Jazmín; Podio, Linda; Radley, Isaac C.; Busquet Rico, Gemma; Ilee, John D.; Liu, Hauyu Baobab; Pineda, Jaime E.; Pontoppidan, Klaus M.; Macías, Enrique; Maureira, María José; Bianchi, Eleonora; Bourke, Tyler L.; Codella, Claudio
Utilizing the James Webb Space Telescope (JWST), the Atacama Large Millimeter/submillimeter Array (ALMA), and the Very Large Array (VLA), we present high angular resolution (0 06–0 42), multiwavelength (4 μm–3 cm) observations of the VLA 1623-2417 protostellar system to characterize the origin, morphology and, properties of the continuum emission. JWST observations at 4.4 μm reveal outflow cavities for VLA 1623 A and, for the first time, VLA 1623 B, as well as scattered light from the upper layers of the VLA 1623 W disk. We model the millimeter-centimeter spectral energy distributions to quantify the relative contributions of dust and ionized gas emission, calculate dust masses, and use spectral index maps to determine where optical depth hinders this analysis. In general, all objects appear to be optically thick down to ∼90 GHz, show evidence for significant amounts (tens to hundreds of M_⊕) of large (>1 mm) dust grains, and are dominated by ionized gas emission for frequencies ≲15 GHz. In addition, we find evidence of unsettled millimeter dust in the inclined disk of VLA 1623 B possibly attributed to instabilities within the circumstellar disk, adding to the growing catalog of unsettled Class 0/I disks. Our results represent some of the highest-resolution observations possible with current instrumentation, particularly in the case of the VLA. However, our interpretation is still limited at low frequencies (≲22 GHz) and thus motivates the need for next-generation interferometers operating at centimeter wavelengths.
ALMA-IMF: XIX. C18O (J = 2─1): Measurements of turbulence in 15 massive protoclusters
(EDP Sciences, 2025-10) Busquet Rico, Gemma; Braine, J.; Liu, H.-L.; Csengeri, T.; Gusdorf, A.; Fernández-López, Manuel; Cunningham, N.; Bronfman, L.; Bonfand, Mélisse; Koley, Atanu; Stutz, Amelia; Louvet, F.; Motte, Frédérique; Ginsburg, A.; Galván-Madrid, Roberto; Álvarez-Gutiérrez, Rodrigo H.; Sanhueza, Patricio; Baug, T.; Sandoval-Garrido, N.; Salinas, J.
ALMA-IMF is a Large Program of the Atacama Large Millimeter/submillimeter Array (ALMA) that aims to determine the origin of the core mass function (CMF) of 15 massive Galactic protoclusters (~1.0─25.0 × 10³ M_⊙ within ~2.5 × 2.5 pc²) located toward the Galactic plane. In addition, the objective of the program is to obtain a thorough understanding of their physical and kinematic properties. Here we study the turbulence in these protoclusters with the C¹⁸O (2─1) emission line using the sonic Mach number analysis (M_s) and the size-linewidth relation. The probability distribution functions (PDFs) for M_s show a similar pattern, exhibiting no clear trend associated with evolutionary stage, peaking in the range between 4 and 7, and then extending to ~25. Such values of M_s indicate that the turbulence in the density regime traced by the C¹⁸O line inside the protoclusters is supersonic in nature. In addition, we compared the non-thermal velocity dispersions (σ_nth,C¹⁸_O) obtained from the C¹⁸O (2─1) line with the non-thermal line widths (σ_{nth, DCN}) of the cores obtained from the DCN (3─2) line. We observed that, on average, the non-thermal linewidth in cores is half that of the gas surrounding them. This suggests that turbulence diminishes at smaller scales or dissipates at the periphery of the cores. Furthermore, we examined the size-linewidth relation for the structures we extracted from the position-position-velocity C¹⁸O (2─1) line emission cube with the dendrogram algorithm. The power-law index (p) obtained from the size-linewidth relation is between 0.41 and 0.64, steeper than the Kolmogorov law of turbulence, as expected for compressible media. In conclusion, this work is one of the first to carry out a statistical study of turbulence for embedded massive protoclusters.
ALMA-IMF: XVIII. The assembly of a star cluster: Dense N2H+ (1─0) kinematics in the massive G351.77 protocluster
(EDP Sciences, 2025-04) Koley, Atanu; Sanhueza, Patricio; Bernal-Mesina, G.; Braine, J.; Bronfman, L.; Busquet Rico, Gemma; Csengeri, T.; Di Francesco, James; Fernández-López, Manuel; Garcia, Pablo; Sandoval-Garrido, Nicolás A.; Stutz, Amelia; Álvarez-Gutiérrez, Rodrigo H.; Galván-Madrid, Roberto; Motte, Frédérique; Ginsburg, A.; Cunningham, N.; Reyes-Reyes, S.; Redaelli, E.; Bonfand, Mélisse; Gusdorf, A.; Salinas, J.; Liu, H.-L.
ALMA-IMF observed 15 massive protoclusters capturing multiple spectral lines and the continuum emission. Here, we focus on the massive protocluster G351.77 (~2500 M⊙, estimated from single-dish continuum observations) located at 2 kpc. We trace the dense gas emission and kinematics with N2H+ (1–0) at ~4 kau resolution. We estimate an N2H+ relative abundance of ~(1.66 ± 0.46) × 10−10. We decompose the N2H+ emission into up to two velocity components, highlighting the kinematic complexity in the dense gas. By examining the position-velocity (PV) and position-position-velocity (PPV) diagrams on small scales, we observe clear inflow signatures (V-shapes) associated with 1.3 mm cores. The most prominent V-shape has a mass inflow rate of ~13.45 × 10−4 M⊙ yr−1 and a short timescale of ~11.42 kyr. We also observe V-shapes without associated cores. This suggests both that cores or centers of accretion exist below the 1.3 mm detection limit, and that the V-shapes may be viable tracers of very early accretion and star formation on ~4 kau scales. The large-scale PV diagram shows that the protocluster is separated into two principal velocity structures separate by ~2 km s−1. Combined with smaller-scale DCN and H2CO emission in the center, we propose a scenario of larger-scale slow contraction with rotation in the center based on simple toy models. This scenario is consistent with previous lines of evidence, and leads to the new suggestion of outside-in evolution of the protocluster as it collapses. The gas depletion times implied by the V-shapes are short (~0.3 Myr), requiring either very fast cluster formation, and/or continuous mass feeding of the protocluster. The latter is possible via the Mother Filament that G351.77 is forming out of. The remarkable similarities in the properties of G351.77 and the recently published work in G353.41 indicate that many of the physical conditions inferred via the ALMA-IMF N2H+ observations may be generic to protoclusters.

Examinar

Enviaments recents