Publications (2024)
Total peer-reviewed articles: 132
Dissipative stabilization of maximal entanglement between nonidentical emitters via two-photon excitation
Authors: Vivas-Viana, Alejandro; Martin-Cano, Diego; Munoz, Carlos Sanchez
Journal: PHYSICAL REVIEW RESEARCH
Publication date: 2024/10/22
DOI: 10.1103/PhysRevResearch.6.043051
Abstract: Two nonidentical quantum emitters, when placed within a cavity and coherently excited at the two-photon resonance, can reach stationary states of nearly maximal entanglement. In Vivas-Via & ntilde;a, Mart & iacute;n-Cano, and S & aacute;nchez entangled W states among strongly interacting quantum emitters embedded in a cavity. Here we delve deeper into a specific configuration with a particularly rich phenomenology: two interacting quantum emitters under coherent excitation at the two-photon resonance. This scenario yields two resonant cavity frequencies where the combination of two-photon driving and Purcell-enhanced decay stabilizes the system into the subradiant and superradiant states, respectively. By considering the case of nondegenerate emitters and exploring the parameter space of the system, we show that this mechanism is merely one among a complex family of phenomena that can generate both stationary and metastable entanglement when driving the emitters at the two-photon resonance. We provide a global perspective of this landscape of mechanisms and contribute analytical characterizations and insights into these phenomena, establishing connections with previous reports in the literature and discussing how some of these effects can be optically detected.
Discovery of two cyano derivatives of acenaphthylene (C12H8) in TMC-1 with the QUIJOTE line survey
Authors: Cernicharo, J.; Cabezas, C.; Fuentetaja, R.; Agundez, M.; Tercero, B.; Janeiro, J.; Juanes, M.; Kaiser, R. I.; Endo, Y.; Steber, A. L.; Perez, D.; Perez, C.; Lesarri, A.; Marcelino, N.; de Vicente, P.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/10/18
DOI: 10.1051/0004-6361/202452196
Abstract: We report the discovery in TMC-1 of two cyano derivatives of the PAH acenaphthylene (C12H8). We have found two series of lines with the QUIJOTE line survey that we assign to 1-C12H7CN and 5-C12H7CN. For the 1-isomer, we have detected and assigned 173 rotational transitions with J up to 46 and K-a up to 9, corresponding to 107 independent frequencies. For the 5-isomer, the identification is based on 56 individual lines, corresponding to 117 rotational transitions with J up to 40 and K-a up to 8. Identification of the carriers was achieved through a careful analysis of the derived rotational constants, which permit us to focus on molecules larger than naphthalene but smaller than anthracene and phenanthrene. Moreover, the derived rotational constants indicate that the species are planar; this allows us to discard derivatives of fluorene and acenaphthene, which are non-planar species. Quantum chemical calculations and subsequent chemical synthesis of these molecules, as well as the observation of their rotational transitions in the laboratory, unequivocally support our identifications. We also confirm, via a robust line-by-line detection, the previous claimed detection of 1- and 2-cyanonaphthalene, which were obtained through statistical stacking techniques. The column densities of 1- and 5-cyanoacenaphthylene are (9.5 +/- 0.9) x 10(11) cm(-2), while those of 1- and 2-cyanonapthalene are (5.5 +/- 0.5) x 10(11) cm(-2). Hence, it seems that acenaphthylene could be a factor of 1.7 more abundant than naphthalene. These results support a scenario in which PAHs grow in cold dark clouds based on fused five- and six-membered carbon rings.
Gas flows in the central region of the Seyfert galaxy NGC 4593 with MUSE
Authors: Mulumba, D.; Knapen, J. H.; Comeron, S.; Almeida, C. Ramos; Obonyo, W. O.; Pereira-Santaella, M.; Baki, P.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/10/17
DOI: 10.1051/0004-6361/202450076
Abstract: Context. Understanding how gas flows into galactic centres, fuels the active galactic nucleus (AGN), and is in turn expelled back through feedback processes is of great importance to appreciate the role AGN play in the growth and evolution of galaxies. Aims. We use Multi Unit Spectroscopic Explorer-adaptive optics (MUSE-AO) optical spectra of the inner 7 ”.5 x 7 ”.5 (1.3 kpc x 1.3 kpc) of the nearby Seyfert 1 galaxy NGC 4593 to characterise its ionised gas kinematics. Methods. We fitted single-Gaussian components to the [O III] lambda 5007 and [N II] lambda 6583 emission lines, and double-Gaussian components to H alpha and H beta to determine the main ionisation mechanism of the gas. To determine the kinematics of the ionised gas, we fit double-Gaussian components to the [O III] lambda 5007 line. Results. The high angular resolution MUSE data (similar to 0 ”. 12 = 20 pc) capture structures of the circumnuclear region including the innermost spiral that feeds the nucleus. Based on the stellar kinematic maps, we confirm the presence of a rotating disc, whilst for the ionised gas, we find high-velocity dispersion values of up to 200 – 250 km s(-1) that show that part of the gas is highly perturbed. The dominant ionisation mechanism of the gas is AGN photoionisation, which reaches the highest values within the innermost 4 ” (680 pc) diameter of the galaxy. At larger radii, the emission line ratios correspond to values in the composite region of the Baldwin, Phillips and Terlevich (BPT) diagram. Conclusions. The broad-component of [O III] lambda 5007 shows blue-shifted velocities on the east side of the central 2 ” (340 pc), which spatially coincide with a region of high velocity-dispersion. This confirms the presence of outflowing gas. We estimate a mass outflow rate and kinetic power of (M) over dot >= 0.048 M-circle dot yr(-1) and E-kin >= 4.09 x 10(39) erg s(-1). The derived mass outflow rate is consistent with that expected from empirical relations between mass outflow rate and AGN luminosity for a low-luminosity AGN such as NGC 4593. High angular resolution integral field observations can enable multi-component analysis of the innermost regions of galaxies, allowing a detailed view of ionised gas flows.
Low temperature dynamics of H + HeH+? H2+ He reaction: On the importance of long-range interaction
Authors: Sahoo, Jayakrushna; Bossion, Duncan; Gonzalez-Lezana, Tomas; Talbi, Dahbia; Scribano, Yohann
Journal: JOURNAL OF CHEMICAL PHYSICS
Publication date: 2024/10/14
DOI: 10.1063/5.0233558
Abstract: While the growing realization of the importance of long-range interactions is being demonstrated in cold and ultracold bimolecular collision experiments, their influence on one of the most critical ion-neutral reactions has been overlooked. Here, we address the non-Langevin abrupt decrease observed earlier in the low-energy integral cross-sections and rate coefficients of the astrochemically important H + HeH+-> H-2(+) + He reaction. We attribute this to the presence of artificial barriers on existing potential energy surfaces (PESs). By incorporating precise long-range interaction terms, we introduce a new refined barrierless PES for the electronic ground state of HeH(2)(+ )reactive system, aligning closely with high-level ab initio electronic energies. Our findings, supported by various classical, quantum, and statistical methods, underscore the significance of long-range terms in accurately modeling reactive PESs. The low-temperature rate coefficient on this new PES shows a substantial enhancement as compared to the previous results and aligns with the Langevin behavior. This enhancement could noticeably affect the prediction of HeH+ abundance in early Universe condition.
Grazing incidence fast atom diffraction: general considerations, semiclassical perturbation theory and experimental implications
Authors: Pollak, E.; Roncin, P.; Allison, W.; Miret-Artes, S.
Journal: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publication date: 2024/10/09
DOI: 10.1039/d4cp02183e
Abstract: Using semiclassical methods, an analytical approach to describe grazing incidence scattering of fast atoms (GIFAD) from surfaces is described. First, we consider a model with a surface corrugated in the scattering plane, which includes the surface normal and the incidence direction. The treatment uses a realistic, Morse potential, within a perturbation approach, and correctly reproduces the basic GIFAD phenomenology, whereby the scattering is directed primarily in the specular direction. Second, we treat the more general case of scattering from a surface corrugated in two-dimensions. Using time averaging along the direction of fast motion in the incidence direction, we derive a time dependent potential for the GIFAD scattering away from a low index direction. The results correctly describe the observation that diffraction is seen only when the scattering plane is aligned close to a low-index direction in the surface plane. For the case of helium scattering from LiF(001) we demonstrate that the resulting theoretical predictions agree well with experiment and show that the analysis provides new information on the scattering time and the length scale of the interaction. The analysis also gives insights into the validity of the axial surface channeling approximation (ASCA) and shows that within first order perturbation theory, along a low-index direction, the full 3-dimensional problem can be represented accurately by an equivalent 2-dimensional problem with a potential averaged along the third dimension. In contrast, away from low-index directions, the effective 2-dimensional potential in the projectile frame is time-dependent. Semiclassical methods are used to describe grazing incidence scattering of fast atoms (GIFAD) from surfaces. Our analytical results illuminate the origin of GIFAD phenomena and describe experiments quantitatively.
Support effects on conical intersections of Jahn-Teller fluxional metal clusters on the sub-nanoscale
Authors: Krupka, Katarzyna M.; de Lara-Castells, Maria Pilar
Journal: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publication date: 2024/10/09
DOI: 10.1039/d4cp03271c
Abstract: The concept of fluxionality has been invoked to explain the enhanced catalytic properties of atomically precise metal clusters of subnanometer size. Cu-3 isolated in the gas phase is a classical case of a fluxional metal cluster where a conical intersection leads to a Jahn-Teller (JT) distortion resulting in a potential energy landscape with close-lying multiminima and, ultimately, fluxional behavior. In spite of the role of conical intersections in the (photo)stability and (photo)catalytic properties of surface-supported atomic metal clusters, they have been largely unexplored. In this work, by applying a high-level multi-reference ab initio method aided with dispersion corrections, we analyze support effects on the conical intersection of Cu-3 considering benzene as a model support molecule of carbon-based surfaces. We verify that the region around the conical intersection and the associated Jahn-Teller (JT) distortion is very slightly perturbed by the support when the Cu-3 cluster approaches it in a parallel orientation: Two electronic states remain degenerate for a structure with C-3 symmetry consistent with the D3h symmetry of unsupported Cu-3 at the conical intersection. It extends over a one-dimensional seam that characterizes a physisorption minimum of the Cu-3-benzene complex. The fluxionality of the Cu-3 cluster, reflected in large fluctuations of relaxed Cu-Cu distances as a function of the active JT mode, is kept unperturbed upon complexation with benzene as well. In stark contrast, for the energetically favored perpendicular orientation of the Cu-3 plane to the benzene ring plane, the conical intersection (CI) is located 12 100 cm(-1) (similar to 1.5 eV) above the chemisorption minimum, with the fluxionality being kept at the CI’s nearby and lost at the chemisorption well. The first excited state at the perpendicular orientation has a deep well (>4000 cm(-1)), being energetically closer to the CI. The transition dipole moment between ground and excited states has a significant magnitude, suggesting that the excited state can be observed through direct photo-excitation from the ground state. Besides demonstrating that the identity of an isolated Jahn-Teller metal cluster can be preserved against support effects at a physisorption state and lifted out at a chemisorption state, our results indicate that a correlation exists between conical intersection topography and fluxionality in the metal cluster’s Cu-Cu motifs.
No evidence of active galactic nucleus features in the nuclei of Arp 220 from JWST/NIRSpec IFS
Authors: Perna, Michele; Arribas, Santiago; Lamperti, Isabella; Pereira-Santaella, Miguel; Ulivi, Lorenzo; Boker, Torsten; Maiolino, Roberto; Bunker, Andrew J.; Charlot, Stephane; Cresci, Giovanni; Rodriguez Del Pino, Bruno; D’Eugenio, Francesco; Ubler, Hannah; Fahrion, Katja; Ceci, Matteo
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/10/07
DOI: 10.1051/0004-6361/202450094
Abstract: Context. Arp 220 is the nearest ultra-luminous infrared galaxy. It shows evidence of 100 pc scale molecular outflows that are likely connected with galaxy-scale outflows traced by ionised and neutral gas. The two highly obscured nuclei of Arp 220 are sites of intense star formation, with extreme (far-infrared based) star formation rate surface densities, Sigma(SFR) greater than or similar to 10(3) M-circle dot yr(-1) kpc(-2). Despite extensive investigations that searched for active galactic nucleus (AGN) activity in the Arp 220 nuclei, direct evidence remains elusive. Aims. We present JWST/NIRSpec integral field spectroscopy (IFS) observations covering the 0.9 – 5.1 mu m wavelength range of the innermost (5 ” x 4 ”, i.e. 1.8 x 1.5 kpc) regions of Arp 220. The primary goal is to investigate the potential presence of AGN signatures in the nuclear regions by analysing the spectra extracted from circular apertures with a radius of 55 pc (0.15 ”) around each of the two nuclei. Methods. The analysis aims to identify highly ionised gas emission lines (with ionisation potential > 54 eV) and other spectral features indicative of AGN activity. Atomic and molecular gas kinematics were also taken into account to study the outflow signatures at < 60 pc scales. Results. We identify similar to 70 atomic and similar to 50 molecular emission lines in the nuclear spectra of Arp 220. We used recombination line ratios to measure optical extinctions in the range A(V) similar to 11 - 14 mag. High-ionisation lines are not detected, except for the [Mg IV] line at 4.49 mu m, which we interpret as due to shocks rather than to AGN ionisation. We identify broadening and multiple kinematic components in the H I and H-2 lines caused by outflows and shocks, with velocities up to similar to 550 km s(-1). Significantly higher velocities (up to similar to 900 km s(-1)) are detected in the off-nuclear regions, but they do not conclusively represent direct evidence for AGN activity. Broad-line region components are not detected in any permitted emission line within the NIRSpec wavelength range. Conclusions. Even with the unprecedented sensitivity of JWST/NIRSpec IFS, achieving an unambiguous identification or exclusion of the presence of an AGN in the Arp 220 system remains challenging because of its extreme dust obscuration.
Mitigating noise in digital and digital-analog quantum computation
Authors: Garcia-Molina, Paula; Martin, Ana; de Andoin, Mikel Garcia; Sanz, Mikel
Journal: COMMUNICATIONS PHYSICS
Publication date: 2024/10/06
DOI: 10.1038/s42005-024-01812-5
Abstract: Noisy Intermediate-Scale Quantum (NISQ) devices lack error correction, limiting scalability for quantum algorithms. In this context, digital-analog quantum computing (DAQC) offers a more resilient alternative quantum computing paradigm that outperforms digital quantum computation by combining the flexibility of single-qubit gates with the robustness of analog simulations. This work explores the impact of noise on both digital and DAQC paradigms and demonstrates DAQC’s effectiveness in error mitigation. We compare the quantum Fourier transform and quantum phase estimation algorithms under a wide range of single and two-qubit noise sources in superconducting processors. DAQC consistently surpasses digital approaches in fidelity, particularly as processor size increases. Moreover, zero-noise extrapolation further enhances DAQC by mitigating decoherence and intrinsic errors, achieving fidelities above 0.95 for 8 qubits, and reducing computation errors to the order of 10-3. These results establish DAQC as a viable alternative for quantum computing in the NISQ era. The authors explore the digital-analog quantum computing paradigm, which combines fast single-qubit gates with the natural dynamics of quantum devices. They find the digital-analog paradigm more robust against certain experimental imperfections than the standard fully-digital one and successfully apply error mitigation techniques to this approach.
Different theoretical aspects of the intrinsic decoherence in the Milburn formalism
Authors: Mousavi, S. V.; Miret-Artes, S.
Journal: EUROPEAN PHYSICAL JOURNAL PLUS
Publication date: 2024/10/03
DOI: 10.1140/epjp/s13360-024-05654-6
Abstract: In this work, we consider different theoretical aspects and simple applications of the Milburn equation which is governed by a parameter controlling what is known as intrinsic decoherence. The main goal is to show some similarities also observed when external decoherence is considered. Linear entropy, Ehrenfest relations, probability density current, the Wigner representation as well as the relation to a Lindbladian master equation are analyzed in terms of this intrinsic decoherence, leading to new insights on the Milburn dynamics. Interference of two wave packets, tunneling and the bouncing ball problem are also studied under this perspective.
Quantum battery supercharging via counter-diabatic dynamics
Authors: de Moraes, L. F. C.; Duriez, Alan C.; Saguia, A.; Santos, Alan C.; Sarandy, M. S.
Journal: QUANTUM SCIENCE AND TECHNOLOGY
Publication date: 2024/10/01
Abstract: We introduce a counter-diabatic (CD) approach for deriving Hamiltonians modeling superchargable quantum batteries (QBs). A necessary requirement for the supercharging process is the existence of multipartite interactions among the cells of the battery. Remarkably, this condition may be insufficient no matter the number of multipartite terms in the Hamiltonian. We analytically illustrate this kind of insufficiency through a model of QB based on the adiabatic version for the Grover search problem. On the other hand, we provide QB supercharging with just a mild number of global connections in the system. To this aim, we consider a spin- 1/2 chain with n sites in the presence of Ising multipartite interactions. We then show that, by considering the validity of the adiabatic approximation and by adding n terms of (n-1)-site interactions, we can achieve a Hamiltonian exhibiting maximum QB power, with respect to a normalized evolution time, growing quadratically with n. Therefore, supercharging can be achieved by O(n) terms of multipartite connections. The time constraint required by the adiabatic approximation can be surpassed by considering a CD expansion in terms of the gauge potential for the original Hamiltonian, with a limited O(n) many-body interaction terms assured via a Floquet approach for the CD implementation.
Methane Formation Efficiency on Icy Grains: Role of Adsorption States
Authors: Tsuge, Masashi; Molpeceres, German; Aikawa, Yuri; Watanabe, Naoki
Journal: ASTROPHYSICAL JOURNAL
Publication date: 2024/10/01
Abstract: Methane (CH4) is one of the major components of the icy mantle of cosmic dust prevalent in cold, dense regions of interstellar media, playing an important role in the synthesis of complex organic molecules and prebiotic molecules. Solid CH4 is considered to be formed via the successive hydrogenation of C atoms accreting onto dust: C + 4H -> CH4. However, most astrochemical models assume this reaction on the ice mantles of dust to be barrierless and efficient, without considering the states of adsorption. Recently, we found that C atoms exist in either the physisorbed or chemisorbed state on compact amorphous solid water, which is analogous to an interstellar ice mantle. These distinct adsorption states considerably affect the hydrogenation reactivity of the C atom. Herein, we elucidate the reactivities of physisorbed and chemisorbed C atoms with H atoms via sequential deposition and codeposition processes. The results indicate that only physisorbed C atoms can produce CH4 on ice. Combining this finding with a previous estimate for the fraction of physisorbed C atoms on ice, we determined the upper limit for the conversion of C atoms into CH4 to be 30%.
The Galaxy Activity, Torus, and Outflow Survey (GATOS). IV. Exploring Ionized Gas Outflows in Central Kiloparsec Regions of GATOS Seyferts
Authors: Zhang, Lulu; Packham, Chris; Hicks, Erin K. S.; Davies, Ric I.; Shimizu, Taro T.; Alonso-Herrero, Almudena; Munoz, Laura Hermosa; Garcia-Bernete, Ismael; Pereira-Santaella, Miguel; Audibert, Anelise; Lopez-Rodriguez, Enrique; Bellocchi, Enrica; Bunker, Andrew J.; Combes, Francoise; Diaz-Santos, Tanio; Gandhi, Poshak; Garcia-Burillo, Santiago; Garcia-Lorenzo, Begona; Gonzalez-Martin, Omaira; Imanishi, Masatoshi; Labiano, Alvaro; Leist, Mason T.; Levenson, Nancy A.; Almeida, Cristina Ramos; Ricci, Claudio; Rigopoulou, Dimitra; Rosario, David J.; Stalevski, Marko; Ward, Martin J.; Esparza-Arredondo, Donaji; Delaney, Dan; Fuller, Lindsay; Haidar, Houda; Honig, Sebastian; Izumi, Takuma; Rouan, Daniel
Journal: ASTROPHYSICAL JOURNAL
Publication date: 2024/10/01
Abstract: Utilizing JWST MIRI/Medium Resolution Spectrograph integral field unit observations of the kiloparsec-scale central regions, we showcase the diversity of ionized gas distributions and kinematics in six nearby Seyfert galaxies included in the GATOS survey. Specifically, we present spatially resolved flux distribution and velocity field maps of six ionized emission lines covering a large range of ionization potentials (15.8-97.1 eV). Based on these maps, we showcase the evidence of ionized gas outflows in the six targets, and find some highly disturbed regions in NGC 5728, NGC 5506, and ESO137-G034. We propose active galactic nucleus (AGN)-driven radio jets plausibly play an important role in triggering these highly disturbed regions. With the outflow rates estimated based on [Ne V] emission, we find the six targets tend to have ionized outflow rates converged to a narrower range than the previous finding. These results have an important implication for the outflow properties in AGN of comparable luminosity.
Formation of the Interstellar Sugar Precursor, (Z)-1,2-Ethenediol, through Radical Reactions on Dust Grains
Authors: del Valle, Juan Carlos; Redondo, Pilar; Kaestner, Johannes; Molpeceres, German
Journal: ASTROPHYSICAL JOURNAL
Publication date: 2024/10/01
Abstract: In recent years, the continued detection of complex organic molecules of prebiotic interest has refueled the interest in a panspermic origin of life. The prebiotic molecule glyceraldehyde is proposed to be formed from (Z)-1,2-ethenediol, a molecule recently detected toward the G+0.693-0.027 molecular cloud at the galactic center. In this work, we computationally simulate the formation of (Z)-1,2-ethenediol from vinyl alcohol on the surface of amorphous solid water in a two-step synthesis involving an OH addition and an H abstraction reaction. In total, we considered all reaction possibilities of the 1,1- and 1,2-OH addition to vinyl alcohol followed by H abstraction or H addition reactions on the resulting radicals. The combination of these reactions is capable of explaining the formation of (Z)-1,2-ethenediol provided a suprathermal diffusion of OH. We also conclude that our proposed formation pathway is not selective and also yields other abstraction and addition products. Key in our findings is the connection between the adsorption modes of the reactants and intermediates and the stereoselectivity of the reactions.
A practical post-Hartree-Fock approach describing open-shell metal cluster-support interactions. Application to Cu3 adsorption on benzene/coronene
Authors: Krupka, Katarzyna M.; Krzeminska, Agnieszka; de Lara-Castells, Maria Pilar
Journal: RSC ADVANCES
Publication date: 2024/10/01
DOI: 10.1039/d4ra05401f
Abstract: Current advances in synthesizing and characterizing atomically precise monodisperse metal clusters (AMCs) at the subnanometer scale have opened up fascinating possibilities in designing new heterogeneous (photo)catalysts as well as functional interfaces between AMCs and biologically relevant molecules. Understanding the nature of AMC-support interactions at molecular-level is essential for optimizing (photo)catalysts performance and designing novel ones with improved properties. M & oslash;ller-Plesset second-order perturbation theory (MP2) is one of the most cost-efficient single-reference post-Hartree-Fock wave-function-based theories that can be applied to AMC-support interactions considering adequate molecular models of the support, and thus complementing state-of-the-art dispersion-corrected density functional theory. However, the resulting AMC-support interaction is typically overestimated with the MP2 method and must be corrected. The coupled MP2 (MP2C) scheme replacing the uncoupled Hartree-Fock dispersion energy by a coupled dispersion contribution, has been proven to describe accurately van-der-Waals (vdW)-dominated interactions between closed-shell AMCs and carbon-based supports. In this work, the accuracy of a MP2C-based scheme is evaluated in modelling open-shell AMC-cluster interactions that imply charge transfer or other strong attractive energy contributions beyond vdW forces. For this purpose, we consider the interaction of Cu-3 with molecular models of graphene of increasing size (benzene and coronene). In this way, it is shown that subchemical precision (within 0.1 kcal mol(-1)) is achieved with the modified MP2C scheme, using the explicitly correlated coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)-F12] as a benchmark method. It is also revealed that the energy difference between uncoupled and coupled dispersion terms closely follows benchmark values of the repulsive intramonomer correlation contribution. The proposed open-shell MP2C-based approach is expected to be of general applicability to open-shell atomic or molecular species interacting with coronene for regions of the potential landscape where single-reference electronic structure descriptions suffice.
H3+ absorption and emission in local (U)LIRGs with JWST/NIRSpec: Evidence for high H2 ionization rates
Authors: Pereira-Santaella, Miguel; Gonzalez-Alfonso, Eduardo; Garcia-Bernete, Ismael; Donnan, Fergus R.; Santa-Maria, Miriam G.; Goicoechea, Javier R.; Lamperti, Isabella; Perna, Michele; Rigopoulou, Dimitra
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/09/26
DOI: 10.1051/0004-6361/202451741
Abstract: We study the 3.4 – 4.4 mu m fundamental rovibrational band of H3+, a key tracer of the ionization of the molecular interstellar medium (ISM), in a sample of 12 local (d < 400 Mpc) (ultra)luminous infrared galaxies ((U)LIRGs) observed with JWST/NIRSpec. The P, Q, and R branches of the band are detected in 13 out of 20 analyzed regions within these (U)LIRGs, which increases the number of extragalactic H3+ detections by a factor of 6. For the first time in the ISM, the H3+ band is observed in emission; we detect this emission in three regions. In the remaining ten regions, the band is seen in absorption. The absorptions are produced toward the 3.4 - 4.4 mu m hot dust continuum rather than toward the stellar continuum, indicating that they likely originate in clouds associated with the dust continuum source. The H3+ band is undetected in Seyfert-like (U)LIRGs where the mildly obscured X-ray radiation from the active galactic nuclei might limit the abundance of this molecule. For the detections, the H3+ abundances, N(H3+)/NH = (0.5 - 5.5)x10-7, imply relatively high ionization rates, zetaH2, of between 3 x 10-16 and > 4 x 10-15 s-1, which are likely associated with high-energy cosmic rays. In half of the targets, the absorptions are blueshifted by 50-180 km s-1, which is lower than the molecular outflow velocities measured using other tracers such as OH 119 mu m or rotational CO lines. This suggests that H3+ traces gas close to the outflow-launching sites before it has been fully accelerated. We used nonlocal thermodynamic equilibrium models to investigate the physical conditions of these clouds. In seven out of ten objects, the H3+ excitation is consistent with inelastic collisions with H2 in warm translucent molecular clouds (Tkin similar to 250-500 K and n(H2) similar to 102 – 3 cm-3). In three objects, dominant infrared pumping excitation is required to explain the absorptions from the (3,0) and (2,1) levels of H3+ detected for the first time in the ISM.