Instituto Carlos I de Física Teórica y Computacional
The Milky Way's inner region is dominated by a stellar bar and a boxy-peanut shaped bulge. However, which stellar populations inhabit the inner Galaxy or how star formation proceeded there is still unknown. The difficulty in studying these stars stems from their location in dense regions that are strongly impacted by extinction and crowding effects. In this work, we use star formation histories computed in the solar neighbourhood using Gaia Colour-Magnitude Diagram fitting to shed light onto the evolution of the central regions of our Galaxy. For that, we have obtained precise age distributions for the non-negligible amount of super metal-rich stars ([M/H] \sim 0.5) in the solar neighbourhood (more than 5%\% of the total stars within 400 pc of the plane). Assuming that these stars were born in the inner Galaxy and migrated outwards, those distributions should be indicative of the true stellar age distribution in the inner Galaxy. Surprisingly, we find that these age distributions are not continuous but show clear signs of episodic star formation (\sim~13.5, 10.0, 7.0, 4.0, 2.0 and less than 1~Gyr ago). Interestingly, with the exception of the 4~Gyr event, the timings of the detected events coincide with the formation of the primitive Milky Way and with known merging events or satellite encounters (Gaia-Enceladus-Sausage, Sagittarius dwarf galaxy, and the Magellanic Clouds), suggesting that these could have induced enhanced and global star-forming episodes. These results are compatible with a scenario in which Gaia-Enceladus-Sausage is responsible for the formation of the bar 10 Gyr ago. However, we cannot associate any accretion counterpart with the 4-Gyr-ago event, leaving room for a late formation of the bar, as previously proposed. A qualitative comparison with the Auriga Superstars simulations suggesting a possible link to bar dynamics and satellite accretion. [Abridged]
The asymmetry between heating and cooling in open quantum systems is a hallmark of nonequilibrium dynamics, yet its thermodynamic origin has remained unclear. Here, we investigate the thermalization of a quantum system weakly coupled to a thermal bath, focusing on the entropy production rate and the quantum thermokinetic uncertainty relation (TKUR). We derive an analytical expression for the entropy production rate, showing that heating begins with a higher entropy production, which drives faster thermalization than cooling. The quantum TKUR links this asymmetry to heat current fluctuations, demonstrating that larger entropy production suppresses fluctuations, making heating more stable than cooling. Our results reveal the thermodynamic basis of asymmetric thermalization and highlight uncertainty relations as key to nonequilibrium quantum dynamics.
Energy storage is a basic physical process with many applications. When considering this task at the quantum scale, it becomes important to optimise the non-equilibrium dynamics of energy transfer to the storage device or battery. Here, we tackle this problem using the methods of quantum feedback control. Specifically, we study the deposition of energy into a quantum battery via an auxiliary charger. The latter is a driven-dissipative two-level system subjected to a homodyne measurement whose output signal is fed back linearly into the driving field amplitude. We explore two different control strategies, aiming to stabilise either populations or quantum coherences in the state of the charger. In both cases, linear feedback is shown to counteract the randomising influence of environmental noise and allow for stable and effective battery charging. We analyse the effect of realistic control imprecisions, demonstrating that this good performance survives inefficient measurements and small feedback delays. Our results highlight the potential of continuous feedback for the control of energetic quantities in the quantum regime.
We report on photoassociation spectroscopy probing the c3Σ1+c^3\Sigma_{1}^+ potential of the bi-alkali NaCs molecule, identifying eleven vibrational lines between v=0v' = 0 and v=25v' = 25 of the excited c3Σ1+c^3\Sigma_{1}^+ potential, and resolving their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines, and its possible link to strong spin-orbit coupling of the c3Σ1+c^3\Sigma_{1}^+ potential with the nearby b3Π1b^3\Pi_1 and B1Π1B^1\Pi_1 manifolds. Finally we report use of the $v' = 22$ line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the X1Σ+X^1\Sigma^+ manifold.
Field dwarf galaxies not actively forming stars are relatively rare in the local Universe, but are present in cosmological hydrodynamical simulations. We use the TNG50 simulation to investigate their origin and find that they all result from environmental effects that have removed or reduced their gas content. Quenched field dwarfs consist of either backsplash objects ejected from a massive host or of systems that have lost their gas after crossing overdense regions such as filaments or sheets (``cosmic web stripping''). Quenched fractions rise steeply with decreasing stellar mass, with quenched systems making up roughly 15%\sim 15\% of all field dwarfs (i.e., excluding satellites) with stellar masses 107109M10^{7}10^9\, M_{\odot} within {1.51.5} Mpc is applied. Of these isolated dwarfs, 6%\sim 6\% are backsplash, while the other 94%\sim 94\% have been affected by the cosmic web. Backsplash systems are more deficient in dark matter, have retained less or no gas, and have stopped forming stars earlier than cosmic web-stripped systems. The discovery of deeply isolated dwarf galaxies which were quenched relatively recently would lend observational support to the prediction that the cosmic web is capable of inducing the cessation of star formation in dwarfs.
We present a detailed study of charged-current (CC) neutrino-nucleus reactions in a fully relativis- tic framework and comparisons with recent experiments spanning an energy range from hundreds of MeV up to 100 GeV within the SuperScaling Approach, which is based on the analysis of electron- nucleus scattering data and has been recently improved with the inclusion of Relativistic Mean Field theory effects. We also evaluate and discuss the impact of two-particle two-hole meson-exchange currents (2p-2h MEC) on neutrino-nucleus interactions through the analysis of two-particle two-hole axial and vector contributions to weak response functions in a fully relativistic Fermi gas. The results show a fairly good agreement with experimental data over the whole range of neutrino energies.
We obtain a quantitative star formation history (SFH) of a shell-like structure ('shell') located in the northeastern part of the Small Magellanic Cloud (SMC). We use the Survey of the MAgellanic Stellar History (SMASH) to derive colour-magnitude diagrams (CMDs), reaching below the oldest main-sequence turnoff, from which we compute the SFHs with CMD fitting techniques. We present, for the first time, a novel technique that uses red clump (RC) stars from the CMDs to assess and account for the SMC's line-of-sight depth effect present during the SFH derivation. We find that accounting for this effect recovers a more accurate SFH. We quantify a 7 kpc line-of-sight depth present in the CMDs, in good agreement with depth estimates from RC stars in the northeastern SMC. By isolating the stellar content of the northeastern shell and incorporating the line-of-sight depth into our calculations, we obtain an unprecedentedly detailed SFH. We find that the northeastern shell is primarily composed of stars younger than 500 Myrs, with significant star formation enhancements around 250 Myr and 450 Myr. These young stars are the main contributors to the shell's structure. We show synchronicity between the northeastern shell's SFH with the Large Magellanic Cloud's (LMC) northern arm, which we attribute to the interaction history of the SMC with the LMC and the Milky Way (MW) over the past 500 Myr. Our results highlight the complex interplay of ram pressure stripping and the influence of the MW's circumgalactic medium in shaping the SMC's northeastern shell.
We aim to investigate how the local environment influences the star formation history (SFH) of galaxies residing in various large-scale environments. We categorise a sample of 9384 galaxies into the three primary large scale structures (voids, walls \& filaments, and clusters) and further classify them based on their local environment (as either "singlets" or group members), through a search of companion galaxies within sky-projected distances $\Delta r_p < 0.45Mpcandvelocitydifferences Mpc and velocity differences \Delta v < 160 \text{km s}^{-1}$. Subsequently, we explore these subsamples through SFH data from previous works. Throughout the study, galaxies are divided into long-timescale SFH galaxies (LT-SFH), which assemble their mass steadily along cosmic time, and short-timescale SFH galaxies (ST-SFH), which form their stars early. We then compare characteristic mass assembly look-back times. The distributions of mass assembly look-back times in ST-SFH galaxies are statistically different for singlets and groups. These differences are only found in LT-SFH galaxies when studying these distributions in stellar mass bins. Our results indicate that the large-scale environment is related to a delay in mass assembly of up to \sim2 Gyr, while this delay is &lt;1 Gyr in the case of local environment. The effect of both kinds of environment is more significant in less massive galaxies, and in LT-SFHs. Our results are consistent with galaxies in groups assembling their stellar mass earlier than singlets, especially in voids and lower mass galaxies. Local environment plays a relevant role in stellar mass assembly times, although we find that large-scale structures also cause a delay in mass assembly, more so in the case of cluster galaxies.
Aims: The physics driving features such as breaks observed in galaxy surface brightness (SB) profiles remains contentious. Here, we assess the importance of stellar radial motions in shaping their characteristics. Methods: We use the simulated Milky Way-mass, cosmological discs, from the Ramses Disc Environment Study (RaDES) to characterise the radial redistribution of stars in galaxies displaying type I (pure exponentials), II (downbending), and III (upbending) SB profiles. We compare radial profiles of the mass fractions and the velocity dispersions of different sub-populations of stars according to their birth and current locations. Results: Radial redistribution of stars is important in all galaxies regardless of their light profiles. Type II breaks seem to be a consequence of the combined effects of outward-moving and accreted stars. The former produces shallower inner profiles (lack of stars in the inner disc) and accumulate material around the break radius and beyond, strengthening the break; the latter can weaken or even convert the break into a pure exponential. Further accretion from satellites can concentrate material in the outermost parts, leading to type III breaks that can coexist with type II breaks, but situated further out. Type III galaxies would be the result of an important radial redistribution of material throughout the entire disc, as well as a concentration of accreted material in the outskirts. In addition, type III galaxies display the most efficient radial redistribution and the largest number of accreted stars, followed by type I and II systems, suggesting that type I galaxies may be an intermediate case between types II and III. In general, the velocity dispersion profiles of all galaxies tend to flatten or even ncrease around the locations where the breaks are found. The age and metallicity profiles are also affected, exhibiting...[abridged]
Accurate star formation histories (SFHs) of galaxies are fundamental for understanding the build-up of their stellar content. However, the most accurate SFHs - those obtained from colour-magnitude diagrams (CMDs) of resolved stars reaching the oldest main sequence turnoffs (oMSTO) - are presently limited to a few systems in the Local Group. It is therefore crucial to determine the reliability and range of applicability of SFHs derived from integrated light spectroscopy, as this affects our understanding of unresolved galaxies from low to high redshift. To evaluate the reliability of current full spectral fitting techniques in deriving SFHs from integrated light spectroscopy by comparing SFHs from integrated spectra to those obtained from deep CMDs of resolved stars. We have obtained a high signal--to--noise (S/N \sim 36.3 per \AA) integrated spectrum of a field in the bar of the Large Magellanic Cloud (LMC) using EFOSC2 at the 3.6 meter telescope at La Silla Observatory. For this same field, resolved stellar data reaching the oMSTO are available. We have compared the star formation rate (SFR) as a function of time and the age-metallicity relation (AMR) obtained from the integrated spectrum using {\tt STECKMAP}, and the CMD using the IAC-star/MinnIAC/IAC-pop set of routines. For the sake of completeness we also use and discuss other synthesis codes ({\tt STARLIGHT} and {\tt ULySS}) to derive the SFR and AMR from the integrated LMC spectrum. We find very good agreement (average differences \sim 4.1 %\%) between the SFR(t) and the AMR obtained using {\tt STECKMAP} on the integrated light spectrum, and the CMD analysis. {\tt STECKMAP} minimizes the impact of the age-metallicity degeneracy and has the advantage of preferring smooth solutions to recover complex SFHs by means of a penalized χ2\chi^2. [abridged]
MACS J0600.1-2008 (MACS0600) is an X-ray luminous, massive galaxy cluster at zd=0.43z_{\mathrm{d}}=0.43, studied previously by the REionization LensIng Cluster Survey (RELICS) and ALMA Lensing Cluster Survey (ALCS) projects which revealed a complex, bimodal mass distribution and an intriguing high-redshift object behind it. Here, we report on the results of a combined analysis of the extended strong lensing (SL), X-ray, Sunyaev-Zeldovich (SZ), and galaxy luminosity-density properties of this system. Using new JWST and ground-based Gemini-N and Keck data, we obtain 13 new spectroscopic redshifts of multiply imaged galaxies and identify 12 new photometric multiple-image systems and candidates, including two multiply imaged z7z\sim7 objects. Taking advantage of the larger areal coverage, our analysis reveals an additional bimodal, massive SL structure which we measure spectroscopically to lie adjacent to the cluster and whose existence was implied by previous SL-modeling analyses. While based in part on photometric systems identified in ground-based imaging requiring further verification, our extended SL model suggests that the cluster may have the second-largest critical area and effective Einstein radius observed to date, Acrit2.16arcmin2A_{\mathrm{crit}}\simeq2.16 \mathrm{arcmin}^2 and θE=49.7±5.0\theta_{\mathrm{E}}=49.7''\pm5.0'' for a source at zs=2z_{\mathrm{s}}=2, enclosing a total mass of M(&lt;\theta_{\mathrm{E}})=(4.7\pm0.7)\times10^{14} \mathrm{M}_{\odot}. These results are also supported by the galaxy luminosity distribution, the SZ and X-ray data. Yet another, probably related massive cluster structure, discovered in X-rays 55' (1.7 Mpc) further north, suggests that MACS0600 is part of an even larger filamentary structure. This discovery adds to several recent detections of massive structures around SL galaxy clusters and establishes MACS0600 as a prime target for future high-redshift surveys with JWST.
We use a sample of 536 \hii\ regions located in nearby spirals, with an homogeneous determination of their TeT_e-based abundances, to obtain new empirical calibrations of the N2O2, N2S2, O3N2, and N2 strong-line indices to estimate the nitrogen-to-oxygen abundance ratio when auroral lines are not detected. All indices are strongly correlated with the TeT_e-based log\log(N/O) for our \hii\ region sample, even more strongly than with 12+log12+\log(O/H). N2O2 is the most strongly correlated index, and the best fit to the log\log(N/O)-N2O2 relation is obtained with a second-order polynomial. The derived relation has a low dispersion ({\em rms}&lt;0.09~dex), being valid in the range -1.74 &lt; N2O2 &lt; 0.62 (or -1.81 &lt; log\log(N/O) &lt; -0.13). We have compared our calibration with previous ones and have discussed the differences between them in terms of the nature of the objects used as calibrators.
We report galaxy MACS0416-Y3 behind the lensing cluster MACSJ0416.1--2403 as a tentative rotating disk at z=8.34z=8.34 detected through its [OIII]λ5007\lambda5007 emission in JWST NIRCam wide-field slitless spectroscopic observations. The discovery is based on our new grism dynamical modeling methodology for JWST NIRCam slitless spectroscopy, using the data from ``Median-band Astrophysics with the Grism of NIRCam in Frontier Fields'' (MAGNIF), a JWST Cycle-2 program. The [OIII]λ5007\lambda5007 emission line morphology in grism data shows velocity offsets compared to the F480M direct imaging, suggestive of rotation. Assuming a geometrically thin disk model, we constrain the rotation velocity of $v_{\rm rot}=58^{+53}_{-35}kms km s^{-1}$ via forward modeling of the two-dimensional (2D) spectrum. We obtain the kinematic ratio of $v_{\rm rot}/\sigma_v=1.6^{+1.9}_{-0.9},where, where \sigma_v$ is the velocity dispersion, in line with a quasi-stable thin disk. The resulting dynamical mass is estimated to be log(Mdyn/M)=8.40.7+0.5\log(M_{\rm dyn}/M_{\odot})=8.4^{+0.5}_{-0.7}. If the rotation confirmed, our discovery suggests that rotating gaseous disks may have already existed within 600 million years after Big Bang.
The transport of biomolecules, drugs, or reactants encapsulated inside stimuli-responsive polymer networks in aqueous media is fundamental for many material and environmental science applications, including drug delivery, biosensing, catalysis, nanofiltration, water purification, and desalination. The transport is particularly complex in dense polymer media, such as collapsed hydrogels, where the molecules strongly interact with the polymer network and diffuse via a hopping mechanism. In this study, we employ Dynamical Density Functional Theory (DDFT) to investigate the non-equilibrium release kinetics of non-ionic subnanometer-sized molecules initially uploaded inside collapsed microgel particles. The theory is consistent with previous molecular dynamics simulations of collapsed poly(NN-isopropylacrylamide) (PNIPAM) polymer matrices, accommodating molecules of varying shapes and sizes. We found that, despite the intricate physico-chemical properties involved in the released process, the kinetics is predominantly dictated by two material parameters: the diffusion coefficient of the molecules inside the microgel (DD^*) and the interaction free energy of the molecules with the microgel (ΔG\Delta G). Our results reveal two distinct limiting regimes: For large, slowly diffusing molecules weakly attracted to the polymer network, the release is primarily driven by diffusion, with a release time that scales as τ1/21/D\tau_{1/2} \sim 1/D^*. Conversely, for small molecules strongly attracted to the polymer network, the release time is dominated by the interaction, scaling as τ1/2exp(ΔG/kBT)\tau_{1/2} \sim \exp(-\Delta G/k_{\textrm{B}} T). Our DDFT calculations are directly compared with an analytical equation for the half-release time, demonstrating excellent quantitative agreement. This equation represents a valuable tool for predicting release kinetics of non-ionic molecules from collapsed microgels.
A crucial aspect of galaxy evolution is the pace at which galaxies build up their mass. We can investigate this hierarchical assembly by uncovering and timing accretion events that our galaxy has experienced. In the Milky Way, accreted debris has been previously identified in the local halo, thanks to the advent of Gaia data. We aim to couple this dataset with advancements in colour-magnitude diagram fitting techniques to characterise the building blocks of the Galaxy. Here we focus on the retrograde halo, specifically Thamnos and Sequoia. We do this as part of the ChronoGal project by fitting absolute colour-magnitude diagrams (using CMDft.Gaia) of samples of stars associated with these substructures, extracted from a local 5D Gaia DR3 dataset. Comparing their derived age and metallicity distributions with those of the expected contamination, from the dominant Gaia Enceladus and low energy in-situ populations, we can unveil the stellar population signatures of the progenitors of Sequoia and Thamnos. We show that both Thamnos and Sequoia have a metal-poor population ([Fe/H]<-1.5 dex) that is distinct from the expected contamination. The age distributions allow us to see that Sequoia formed half of its stars by a lookback time of 12 Gyr, while Thamnos is on average older, having formed half its stars at 12.3 Gyr. Gaia Enceladus and the low energy in-situ populations formed half of their stars by 12.1 Gyr and 12.9 Gyr respectively. This suggests that Thamnos was accreted earlier than Gaia Enceladus and Sequoia is the most recent accretion event. We have presented, for the first time, age distributions of the retrograde halo substructures: Sequoia and Thamnos. These are derived purely photometrically using CMD fitting techniques, which also provide metallicity distributions that successfully reproduce the spectroscopic distributions, highlighting the capability of CMDft.Gaia.
Quantum self-testing is the task of certifying quantum states and measurements using the output statistics solely, with minimal assumptions about the underlying quantum system. It is based on the observation that some extremal points in the set of quantum correlations can only be achieved, up to isometries, with specific states and measurements. Here, we present a new approach for quantum self-testing in Bell non-locality scenarios, motivated by the following observation: the quantum maximum of a given Bell inequality is, in general, difficult to characterize. However, it is strictly contained in an easy-to-characterize set: the \emph{theta body} of a vertex-weighted induced subgraph (G,w)(G,w) of the graph in which vertices represent the events and edges join mutually exclusive events. This implies that, for the cases where the quantum maximum and the maximum within the theta body (known as the Lovász theta number) of (G,w)(G,w) coincide, self-testing can be demonstrated by just proving self-testability with the theta body of GG. This graph-theoretic framework allows us to (i) recover the self-testability of several quantum correlations that are known to permit self-testing (like those violating the Clauser-Horne-Shimony-Holt (CHSH) and three-party Mermin Bell inequalities for projective measurements of arbitrary rank, and chained Bell inequalities for rank-one projective measurements), (ii) prove the self-testability of quantum correlations that were not known using existing self-testing techniques (e.g., those violating the Abner Shimony Bell inequality for rank-one projective measurements). Additionally, the analysis of the chained Bell inequalities gives us a closed-form expression of the Lovász theta number for a family of well-studied graphs known as the Möbius ladders, which might be of independent interest in the community of discrete mathematics.
In this work we study the helium atom confined in a spherical impenetrable cavity by using informational entropies. We use the variational method to obtain the energies and wave functions of the confined helium atom as a function of the cavity radius r0r_0. As trial wave functions we use one uncorrelated function and four functions with different degrees of electronic correlation. We computed the Shannon entropy, Fisher information, Kullback--Leibler entropy, Disequilibrium, Tsallis entropy and Fisher--Shannon complexity, as a function of the box radius r0r_0. We found that these entropic measures are sensitive to electronic correlation and can be used to measure it. These entropic measures are less sensitive to electron correlation in the strong confinement regime (r_0&lt;1 a.u.).
We report coherent association of atoms into a single weakly bound NaCs molecule in an optical tweezer through an optical Raman transition. The Raman technique uses a deeply bound electronic excited intermediate state to achieve a large transition dipole moment while reducing photon scattering. Starting from two atoms in their relative motional ground state, we achieve an optical transfer efficiency of 69%. The molecules have a binding energy of 770.2MHz at 8.83(2)G. This technique does not rely on Feshbach resonances or narrow excited-state lines and may allow a wide range of molecular species to be assembled atom-by-atom.
This article gives an overview and a perspective of recent theoretical proposals and their experimental implementations in the field of quantum machine learning. Without an aim to being exhaustive, the article reviews specific high-impact topics such as quantum reinforcement learning, quantum autoencoders, and quantum memristors, and their experimental realizations in the platforms of quantum photonics and superconducting circuits. The field of quantum machine learning could be among the first quantum technologies producing results that are beneficial for industry and, in turn, to society. Therefore, it is necessary to push forward initial quantum implementations of this technology, in Noisy Intermediate-Scale Quantum Computers, aiming for achieving fruitful calculations in machine learning that are better than with any other current or future computing paradigm.
We introduce a general method which converts, in a unified way, any form of quantum contextuality, including any form of state-dependent contextuality, into a quantum violation of a bipartite Bell inequality. As an example, we apply the method to a quantum violation of the Klyachko-Can-Binicio\u{g}lu-Shumovsky inequality.
There are no more papers matching your filters at the moment.