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AGN candidates in the VVV near-IR galaxy catalogue
(2023-04) Baravalle, Laura D.; Schmidt, Eduardo O.; Victoria Alonso M.; Pichel, Ana; Minniti, Dante; Rodríguez-Kamenetzky, Adriana R.; Masetti, Nicola; Villalon, Carolina; Smith, Leigh C.; Lucas, Philip W.
The goal of this work is to search for Active Galactic Nuclei (AGN) in the Galactic disc at very low latitudes with |b| < 2◦. For this, we studied the five sources from the VVV near-infrared (IR) galaxy catalogue that have also WISE counterparts and present variability in the VIrac VAriable Classification Ensemble (VIVACE) catalogue. In the near-IR colour-colour diagrams, these objects have in general redder colours compared to the rest of the sources in the field. In the mid-IR ones, they are located in the AGN region, however, there is a source that presents the highest interstellar extinction and different mid-IR colours to be a young stellar object (YSO). We also studied the source variability using two different statistical methods. The fractional variability amplitude σrms ranges from 12.6 to 33.8, being in concordance with previous results found for type-1 AGNs. The slopes of the light curves are in the range (2.6-4.7) × 10-4 mag d-1, also in agreement with results reported on quasars variability. The combination of all these results suggest that four galaxies are type-1 AGN candidates, whereas the fifth source likely a YSO candidate. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
M dwarf stars in the b294 field from the VISTA Variables in the Vía Láctea (VVV)
(Oxford University Press, 2023-04) Cruz, Patricia; Cortés-Contreras, Miriam; Solano, Enrique; Rodrigo, Carlos; Minniti, Dante; Alonso-García, Javier; Saito, Roberto K.
M dwarf stars are the dominant stellar population in the Milky Way, and they are important for a wide variety of astrophysical topics. The Gaia mission has delivered a superb collection of data, nevertheless, ground-based photometric surveys are still needed to study faint objects. Therefore, the present work aims to identify and characterize M dwarf stars in the direction of the Galactic bulge using photometric data and with the help of Virtual Observatory tools. Using parallax measurements and proper motions from Gaia Data Release 3, in addition to different colour-cuts based on VISTA filters, we identify and characterize 7 925 M dwarf stars in the b294 field from the Vista Variables in the Vía Láctea (VVV) survey. We performed a spectral energy distribution fitting to obtain the effective temperature for all objects using photometric information available at Virtual Observatory archives. The objects in our sample have temperatures varying from 2800–3900 K. We also search for periodic signals in VVV light curves with up to 300 epochs, approximately. As a secondary outcome, we obtain periods for 82 M dwarfs by applying two methods: the Lomb–Scargle and Phase Dispersion Minimization methods, independently. These objects, with periods ranging from 0.14–34 d, are good candidates for future ground-based follow up. Our sample has increased significantly the number of known M dwarfs in the direction of the Galactic bulge and within 500 pc, showing the importance of ground-based photometric surveys in the near-infrared. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
The chemical characterization of halo substructure in the Milky Way based on APOGEE
(Oxford University Press, 2023-04) Horta, Danny; Schiavon, Ricardo P.; Mackereth, J. Ted; Weinberg, David H.; Hasselquist, Sten; Feuillet, Diane; O’Connell, Robert W.; Anguiano, Borja; Allende-Prieto, Carlos; Beaton, Rachael L.; Bizyaev, Dmitry; Cunha, Katia; Geisler, Doug; García-Hernández D.A.; Holtzman, Jon; Jönsson, Henrik; Lane, Richard R.; Majewski, Steve R.; Mészáros, Szabolcs; Minniti, Dante; Nitschelm, Christian; Shetrone, Matthew; Smith, Verne V.; Zasowski, Gail
Galactic haloes in a Λ-CDM universe are predicted to host today a swarm of debris resulting from cannibalized dwarf galaxies. The chemodynamical information recorded in their stellar populations helps elucidate their nature, constraining the assembly history of the Galaxy. Using data from APOGEE and Gaia, we examine the chemical properties of various halo substructures, considering elements that sample various nucleosynthetic pathways. The systems studied are Heracles, Gaia-Enceladus/Sausage (GES), the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1, Arjuna, I’itoi, Nyx, Icarus, and Pontus. Abundance patterns of all substructures are cross-compared in a statistically robust fashion. Our main findings include: (i) the chemical properties of most substructures studied match qualitatively those of dwarf Milky Way satellites, such as the Sagittarius dSph. Exceptions are Nyx and Aleph, which are chemically similar to disc stars, implying that these substructures were likely formed in situ; (ii) Heracles differs chemically from in situ populations such as Aurora and its inner halo counterparts in a statistically significant way. The differences suggest that the star formation rate was lower in Heracles than in the early Milky Way; (iii) the chemistry of Arjuna, LMS-1, and I’itoi is indistinguishable from that of GES, suggesting a possible common origin; (iv) all three Sequoia samples studied are qualitatively similar. However, only two of those samples present chemistry that is consistent with GES in a statistically significant fashion; (v) the abundance patterns of the Helmi stream and Thamnos are different from all other halo substructures. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Searching for Systems with Planar Hexacoordinate Carbons
(MDPI, 2023-03) Inostroza, Diego; Leyva-Parra, Luis; Yañez, Osvaldo; Solar-Encinas, José; Vásquez-Espinal, Alejandro; Valenzuela, Maria Luisa; Tiznado, William
Here, we present evidence that the D2h M2C50/2+ (M = Li-K, Be-Ca, Al-In, and Zn) species comprises planar hexacoordinate carbon (phC) structures that exhibit four covalent and two electrostatic interactions. These findings have been made possible using evolutionary methods for exploring the potential energy surface (AUTOMATON program) and the Interacting Quantum Atoms (IQA) methodology, which support the observed bonding interactions. It is worth noting, however, that these structures are not the global minimum. Nonetheless, incorporating two cyclopentadienyl anion ligands (Cp) into the CaC52+ system has enhanced the relative stability of the phC isomer. Moreover, cycloparaphenylene ([8]CPP) provides system protection and kinetic stability. These results indicate that using appropriate ligands presents a promising approach for expanding the chemistry of phC species. © 2023 by the authors.
Temperature constraints on the coldest brown dwarf known: WISE 0855-0714
(EDP Sciences, 2014-12) Beamín J.C.; Ivanov V.D.; Bayo A.; Mužić K.; Boffin H.M.J.; Allard F. f; Homeier D.; Minniti D.; Gromadzki M.; Kurtev R.; Lodieu N.; Martin E.L.; Mendez R.A.
Context. Nearby isolated planetary mass objects are beginning to be discovered, but their individual properties are poorly constrained because their low surface temperatures and strong molecular self-absorption make them extremely faint. Aims. We aimed to detect the near-infrared emission of the coldest brown dwarf (BD) found so far, WISE0855-0714, located ~2.2 pc away, and to improve its temperature estimate (Teff = 225-260 K) from a comparison with state-of-the-art models of BD atmospheres. Methods. We observed the field containing WISE0855-0714 with HAWK-I at the VLT in the Y band. For BDs with Teff< 500 K theoretical models predict strong signal (or rather less molecular absorption) in this band. Results. WISE0855-0714 was not detected in our Y-band images, thus placing an upper limit on its brightness to Y> 24.4 mag at 3σ level, leading to Y-[4.5] > 10.5. Combining this limit with previous detections and upper limits at other wavelengths, WISE0855-0714 is confirmed as the reddest BD detected, further supporting its status as the coldest known brown dwarf. We applied spectral energy distribution fitting with collections of models from two independent groups for extremely cool BD atmospheres leading to an effective temperature of Teff< 250 K, © 2014 ESO.
M dwarfs in the b201 tile of the VVV survey: Colour-based selection, spectral types and light curves
(EDP Sciences, 2014-11) Rojas-Ayala, Bárbara; Iglesias, Daniela; Minniti, Dante; Saito, Roberto K.; Surot, Francisco
Context. The intrinsically faint M dwarfs are the most numerous stars in the Galaxy, have main-sequence lifetimes longer than the Hubble time, and host some of the most interesting planetary systems known to date. Their identification and classification throughout the Galaxy is crucial to unraveling the processes involved in the formation of planets, stars, and the Milky Way. The ESO Public Survey VVV is a deep near-IR survey mapping the Galactic bulge and southern plane. The VVV b201 tile, located in the border area of the bulge, was specifically selected for the characterisation of M dwarfs. Aims. We used VISTA photometry to identify M dwarfs in the VVV b201 tile, to estimate their subtypes, and to search for transit-like light curves from the first 26 epochs of the survey. Methods. UKIDSS photometry from SDSS spectroscopically identified M dwarfs was used to calculate their expected colours in the YJHKs VISTA system. A colour-based spectral subtype calibration was computed. Possible giants were identified by a (J-Ks,HJ) reduced proper motion diagram. The light curves of 12.8
Experimental activities in the laboratory of analytical chemistry under an inquiry approach
(Sociedad Chilena de Quimica, 2014-12) Arias, Helen; Lazo, Leontina; Cañas, Francisco
This study analyzes the perception, development and improvement of the cognitive abilities of undergraduate students (of biochemistry and industrial chemistry) through the application of an inquiry methodology in the laboratory of analytical chemistry. The study was conducted during one semester. The instruments for data collection were a Test of Critical Thinking and a Questionnaire to determine the perception of the inquiry methodology and the traditional methodology, applied at the beginning and at the end of the semester. The results show an improvement in cognitive strategies and in the students' perception of the inquiry methodology. This is consistent with future job performance.
KID Procedure Applied on the [(PY5Me2)MoO]+Complex
(American Chemical Society, 2020-12) Glossman-Mitnik, Daniel; Martínez-Araya, Jorge
The KID (Koopmans in DFT) protocol usually applies in organic molecules of the closed-shell type. We used the KID procedure on an open-shell Mo-based system for the first time to choose the most suitable density functional to compute global and local reactivity descriptors obtained from the conceptual density-functional theory (DFT). From a set of 18 density functionals, spread from the second until the fourth rung of Jacob's ladder: BLYP, BP86, B97-D, MN12-L, MN15-L, M06-L, M11-L, CAM-B3LYP, PBE0, B3LYP, N12-SX, M06-2X, MN15, MN12-SX, ωB97X-D, M11, LC-ωHPBE, and APFD, we concluded that CAM-B3LYP provides the best outcome, and in the second place, M06-2X. Because the vertical first ionization potential and vertical first electron affinity in the ground state (gs) are defined as follows I = Egs(N - 1) - Egs(N) and A = Egs(N) - Egs(N + 1), where Egs(N - 1), Egs(N), and Egs(N + 1) correspond to energies of the system bearing N, N + 1, and N - 1 electrons, along with Koopmans' theorem (KT) given by I ≈ -ϵHOMO (ϵHOMO, highest occupied molecular orbital energy) and A ≈ -ϵLUMO (ϵLUMO, lowest unoccupied molecular orbital energy), the deviation from the KT was performed by the use of the JHL=JI2+JA2 index, such that JI = |Egs(N - 1) - Egs(N) + ϵHOMO| and JA = |Egs(N) - Egs(N + 1) + ϵLUMO|, which are absolute deviations from the perspective of I and A, respectively. Furthermore, the ϵSOMO (SOMO: singly-occupied molecular orbital energy) leads us to another index given by |ΔSL| = |ϵSOMO - ϵLUMO|. Therefore, JHL and |ΔSL| are indexes defined to evaluate the quality of the KT when employed within the context of quantum chemical calculations based on DFT and not the Hartree-Fock theory. We propose the JHLS=JHL2+|ΔSL|2 index that could be more suitable to choose the most proper density functional because the JHL and |ΔSL| are independent indexes. ©
Radial variation of the stellar mass functions in the globular clusters M15 and M30: Clues of a non-standard IMF?
(Oxford University Press, 2020-12) Cadelano M.; Dalessandro E.; Webb J.J.; Vesperini E.; Lattanzio D.; Beccari G.; Gomez M.; Monaco L.
We exploit a combination of high-resolution Hubble Space Telescope and wide-field ESO-VLT observations to study the slope of the global mass function (αG) and its radial variation (α(r)) in the two dense, massive and post core-collapse globular clusters M15 and M30. The available data set samples the clusters' main sequence down to ∼0.2 M⊙ and the photometric completeness allows the study of the mass function between 0.40 M⊙ and 0.75 M⊙ from the central regions out to their tidal radii. We find that both clusters show a very similar variation in α(r) as a function of clustercentric distance. They both exhibit a very steep variation in α(r) in the central regions, which then attains almost constant values in the outskirts. Such a behaviour can be interpreted as the result of long-term dynamical evolution of the systems driven by mass-segregation and mass-loss processes. We compare these results with a set of direct N-body simulations and find that they are only able to reproduce the observed values of α(r) and αG at dynamical ages (t/trh) significantly larger than those derived from the observed properties of both clusters. We investigate possible physical mechanisms responsible for such a discrepancy and argue that both clusters might be born with a non-standard (flatter/bottom-lighter) initial mass function. © 2020 The Author(s).
Automated classification of eclipsing binary systems in the VVV Survey
(Oxford University Press, 2023-03) Daza-Perilla I.V.; Gramajo L.V.; Lares M.; Palma T.; Lopes, C.E. Ferreira; Minniti D.; Clariá J.J.
With the advent of large-scale photometric surveys of the sky, modern science witnesses the dawn of big data astronomy, where automatic handling and discovery are paramount. In this context, classification tasks are among the key capabilities a data reduction pipeline must possess in order to compile reliable data sets, to accomplish data processing with an efficiency level impossible to achieve by means of detailed processing and human intervention. The VISTA Variables of the Vía Láctea Survey, in the southern part of the Galactic disc, comprises multiepoch photometric data necessary for the potential discovery of variable objects, including eclipsing binary systems (EBs). In this study, we use a recently published catalogue of one hundred EBs, classified by fine-tuning theoretical models according to contact, detached, or semidetached classes belonging to the tile d040 of the VVV. We describe the method implemented to obtain a supervised machine-learning model, capable of classifying EBs using information extracted from the light curves of variable object candidates in the phase space from tile d078. We also discuss the efficiency of the models, the relative importance of the features and the future prospects to construct an extensive data base of EBs in the VVV survey. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
The VISCACHA survey - VI. Dimensional study of the structure of 82 star clusters in the Magellanic Clouds
(Oxford University Press, 2023-03) Jimena Rodríguez M.; Feinstein C.; Baume G.; Dias B.; Maia F.S.M.; Santos J.F.C.; Kerber L.; Minniti D.; Pérez-Villegas A.; De Bórtoli B.; Parisi M.C.; Oliveira R.A.P.
We present a study of the internal structure of 82 star clusters located at the outer regions of the Large Magellanic Cloud and the Small Magellanic Cloud using data of the VISCACHA Survey. Through the construction of the minimum spanning tree, which analyses the relative position of stars within a given cluster, it was possible to characterize the internal structure and explore the fractal or subclustered distribution for each cluster. We computed the parameters m (which is the average length of the connected segments normalized by the area), s (which is the mean points separation in units of cluster radius), and Q (the ratio of these components). These parameters are useful to distinguish between radial, homogeneous, and substructured distributions of stars. The dependence of these parameters with the different characteristics of the clusters, such as their ages and spatial distribution, was also studied. We found that most of the studied clusters present a homogeneous stellar distribution or a distribution with a radial concentration. Our results are consistent with the models, suggesting that more dynamically evolved clusters seem to have larger Q values, confirming previous results from numerical simulations. There also seems to be a correlation between the internal structure of the clusters and their galactocentric distances, in the sense that for both galaxies, the more distant clusters have larger Q values. We also paid particular attention to the effects of contamination by non-member field stars and its consequences finding that field star decontamination is crucial for these kinds of studies. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Forbidden hugs in pandemic times: IV. Panchromatic evolution of three luminous red novae
(EDP Sciences, 2023-03) Pastorello A.; Valerin G.; Fraser M.; Reguitti A.; Elias-Rosa N.; Filippenko A.V.; Rojas-Bravo C.; Tartaglia L.; Reynolds T.M.; Valenti S.; Andrews J.E.; Ashall C.; Bostroem K.A.; Brink T.G.; Burke J.; Cai Y.-Z.; Cappellaro E.; Coulter D.A.; Dastidar R.; Davis K.W.; Dimitriadis G.; Fiore A.; Foley R.J.; Fugazza D.; Galbany L.; Gangopadhyay A.; Geier S.; Gutiérrez C.P.; Haislip J.; Hiramatsu D.; Holmbo S.; Howell D.A.; Hsiao E.Y.; Hung T.; Jha S.W.; Kankare E.; Karamehmetoglu E.; Kilpatrick C.D.; Kotak R.; Kouprianov V.; Kravtsov T.; Kumar S.; Li Z.-T.; Lundquist M.J.; Lundqvist P.; Matilainen K.; Mazzali P.A.; McCully C.; Misra K.; Morales-Garoffolo A.; Moran S.; Morrell N.; Newsome M.; Padilla Gonzalez E.; Pan Y.-C.; Pellegrino C.; Phillips M.M.; Pignata G.; Piro A.L.; Reichart D.E.; Rest A.; Salmaso I.; Sand D.J.; Siebert M.R.; Smartt S.J.; Smith K.W.; Srivastav S.; Stritzinger M.D.; Taggart K.; Tinyanont S.; Yan S.-Y.; Wang L.; Wang X.-F.; Williams S.C.; Wyatt S.; Zhang T.-M.; De Boer T.; Chambers K.; Gao H.; Magnier E.
We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT 2018bwo, AT 2021afy, and AT 2021blu. AT 2018bwo was discovered in NGC 45 (at about 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 1040 erg s1. AT 2021afy, hosted by UGC 10043 (49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(±0.6) - 1041 erg s1. Finally, for AT 2021blu in UGC 5829 (∼8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT 2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of LRN AT 2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5 - 1040 erg s1, which is half of that of AT 2021afy. The spectra of AT 2021afy and AT 2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT 2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT 2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from about 13 M for AT 2018bwo, to 141+4 M⊙ for AT 2021blu, and over 40 M for AT 2021afy. © 2023 The Authors.
Dark SU (2) Stueckelberg portal
(American Physical Society, 2023-03) Lyubovitskij, Valery E.; Zhevlakov, Alexey S.; Kachanovich, Aliaksei; Kuleshov, Serguei
We study the non-Abelian SU(2)D extension of the U(1)D Stueckelberg portal, which plays the role of mediator between the Standard Model (SM) and dark sector. This portal is specified by the Stueckelberg mechanism for generation of dark gauge boson masses. The proposed U(1)D - SU(2)D Stueckelberg portal has a connection with SM matter fields, in analogy with the familon model. We derive bounds on the couplings of dark portal bosons and SM particles, which govern diagonal and nondiagonal flavor transitions of quarks and leptons. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
Sulfur dioxide in the mid-infrared transmission spectrum of WASP-39b
(Nature Research, 2024-12) Powell, Diana; Feinstein, Adina D.; Lee, Elspeth K. H.; Zhang, Michael; Tsai, Shang-Min; Taylor, Jake; Kirk, James; Bell, Taylor; Barstow, Joanna; Gao, Peter; Bean, Jacob; Blecic, Jasmina; Chubb, Katy L.; Crossfield, Ian J. M.; Jordan, Sean; Kitzmann, Daniel; Moran, Sarah E.; Morello, Giuseppe; Moses, Julianne; Welbanks, Luis; Yang, Jeehyun; Zhang, Xi; Ahrer, Eva-Maria; Bello-Arufe, Aaron; Brande, Jonathan; Casewell S.L.; Crouzet, Nicolas; Cubillos, Patricio E.; Demory, Brice-Olivier; Dyrek, Achrène; Flagg, Laura; Hu, Renyu; Inglis, Julie; Jones, Kathryn D.; Kreidberg, Laura; López-Morales, Mercedes; Lagage, Pierre-Olivier; Meier Valdés, Erik A.; Miguel, Yamila; Parmentier, Vivien; Piette, Anjali A. A.; Rackham, Benjamin V.; Radica, Michael; Redfield, Seth; Stevenson, Kevin B.; Wakeford, Hannah R.; Aggarwal, Keshav; Alam, Munazza K.; Batalha, Natalie M.; Batalha, Natasha E.; Benneke, Björn; Berta-Thompson, Zach K.; Brady, Ryan P.; Caceres, Claudio; Carter, Aarynn L.; Désert, Jean-Michel; Harrington, Joseph; Iro, Nicolas; Line, Michael R.; Lothringer, Joshua D.; MacDonald, Ryan J.; Mancini, Luigi; Molaverdikhani, Karan; Mukherjee, Sagnick; Nixon, Matthew C.; Oza, Apurva V.; Palle, Enric; Rustamkulov, Zafar; Sing, David K.; Steinrueck, Maria E.; Venot, Olivia; Wheatley, Peter J.; Yurchenko, Sergei N.
The recent inference of sulfur dioxide (SO2) in the atmosphere of the hot (approximately 1,100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations1–3 suggests that photochemistry is a key process in high-temperature exoplanet atmospheres4. This is because of the low (<1 ppb) abundance of SO2 under thermochemical equilibrium compared with that produced from the photochemistry of H2O and H2S (1–10 ppm)4–9. However, the SO2 inference was made from a single, small molecular feature in the transmission spectrum of WASP-39b at 4.05 μm and, therefore, the detection of other SO2 absorption bands at different wavelengths is needed to better constrain the SO2 abundance. Here we report the detection of SO2 spectral features at 7.7 and 8.5 μm in the 5–12-μm transmission spectrum of WASP-39b measured by the JWST Mid-Infrared Instrument (MIRI) Low Resolution Spectrometer (LRS)10. Our observations suggest an abundance of SO2 of 0.5–25 ppm (1σ range), consistent with previous findings4. As well as SO2, we find broad water-vapour absorption features, as well as an unexplained decrease in the transit depth at wavelengths longer than 10 μm. Fitting the spectrum with a grid of atmospheric forward models, we derive an atmospheric heavy-element content (metallicity) for WASP-39b of approximately 7.1–8.0 times solar and demonstrate that photochemistry shapes the spectra of WASP-39b across a broad wavelength range.
MiNDSTEp differential photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756: Microlensing and a new time delay
(EDP Sciences, 2017) Giannini E.; Schmidt R.W.; Wambsganss J.; Alsubai K.; Andersen J.M.; Anguita T.; Bozza V.; Bramich D.M.; Browne P.; Calchi Novati S.; Damerdji Y.; Diehl C.; Dodds P.; Dominik M.; Elyiv A.; Fang X.; Figuera Jaimes R.; Finet F.; Gerner T.; Gu S.; Hardis S.; Harpsøe K.; Hinse T.C.; Hornstrup A.; Hundertmark M.; Jessen-Hansen J.; Jørgensen U.G.; Juncher D.; Kains N.; Kerins E.; Korhonen H.; Liebig C.; Lund M.N.; Lundkvist M.S.; Maier G.; Mancini L.; Masi G.; Mathiasen M.; Penny M.; Proft S.; Rabus M.; Rahvar S.; Ricci D.; Scarpetta G.; Sahu K.; Schäfer S.; Schönebeck F.; Skottfelt J.; Snodgrass C.; Southworth J.; Surdej J.; Tregloan-Reed J.; Vilela C.; Wertz O.; Zimmer F.
Aims. We present V and R photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756. The data were taken by the MiNDSTEp collaboration with the 1.54 m Danish telescope at the ESO La Silla observatory from 2008 to 2012. Methods. Differential photometry has been carried out using the image subtraction method as implemented in the HOTPAnTS package, additionally using GALFIT for quasar photometry. Results. The quasar WFI 2033-4723 showed brightness variations of order 0.5 mag in V and R during the campaign. The two lensed components of quasar HE 0047-1756 varied by 0.2-0.3 mag within five years. We provide, for the first time, an estimate of the time delay of component B with respect to A of Δt = (7.6 ± 1.8) days for this object. We also find evidence for a secular evolution of the magnitude difference between components A and B in both filters, which we explain as due to a long-duration microlensing event. Finally we find that both quasars WFI 2033-4723 and HE 0047-1756 become bluer when brighter, which is consistent with previous studies. © ESO, 2016.
The ALMA Frontier Fields Survey: I. 1.1 mm continuum detections in Abell 2744, MACS J0416.1-2403 and MACS J1149.5+2223
(EDP Sciences, 2017) González-López J.; Bauer F.E.; Romero-Cañizales C.; Kneissl R.; Villard E.; Carvajal R.; Kim S.; Laporte N.; Anguita T.; Aravena M.; Bouwens R.J.; Bradley L.; Carrasco M.; Demarco R.; Ford H.; Ibar E.; Infante L.; Messias H.; Muñoz Arancibia A.M.; Nagar N.; Padilla N.; Treister E.; Troncoso P.; Zitrin A.
Context. Dusty star-forming galaxies are among the most prodigious systems at high redshift (z> 1), characterized by high starformation rates and huge dust reservoirs. The bright end of this population has been well characterized in recent years, but considerable uncertainties remain for fainter dusty star-forming galaxies, which are responsible for the bulk of star formation at high redshift and thus play a key role in galaxy growth and evolution. Aims. In this first paper of our series, we describe our methods for finding high redshift faint dusty galaxies using millimeter observations with ALMA. Methods. We obtained ALMA 1.1mm mosaic images for three strong-lensing galaxy clusters from the Frontier Fields Survey, which constitute some of the best studied gravitational lenses to date. The 20 20 mosaics overlap with the deep HST WFC3/IR footprints and encompass the high magnification regions of each cluster for maximum intrinsic source sensitivity. The combination of extremely high ALMA sensitivity and the magnification power of these clusters allows us to systematically probe the sub-mJy population of dusty star-forming galaxies over a large surveyed area. Results. We present a description of the reduction and analysis of the ALMA continuum observations for the galaxy clusters Abell 2744 (z = 0:308), MACS J0416.1-2403 (z = 0:396) and MACS J1149.5+2223 (z = 0:543), for which we reach observed rms sensitivities of 55, 59 and 71 Jy beam-1 respectively.We detect 12 dusty star-forming galaxies at S=N 5:0 across the three clusters, all of them presenting coincidence with near-infrared detected counterparts in the HST images. None of the sources fall close to the lensing caustics, thus they are not strongly lensed. The observed 1.1mm flux densities for the total sample of galaxies range from 0.41 to 2.82 mJy, with observed effective radii spanning .00:005 to 00:037 00:021. The lensing-corrected sizes of the detected sources appear to be in the same range as those measured in brighter samples, albeit with possibly larger dispersion. © ESO 2016.
Phenomenological and cosmological implications of a scotogenic three-loop neutrino mass model
(Springer Science and Business Media Deutschland GmbH, 2023-03) Abada, Asmaa; Bernal, Nicolás; Cárcamo Hernández, Antonio E.; Kovalenko, Sergey; de Melo, Téssio B.; Toma, Takashi
We propose a scotogenic model for generating neutrino masses through a three-loop seesaw. It is a minimally extended inert doublet model with a spontaneously broken global symmetry U(1)′ and a preserved ℤ2 symmetry. The three-loop suppression allows the new particles to have masses at the TeV scale without fine-tuning the Yukawa couplings. The model leads to a rich phenomenology while satisfying all the current constraints imposed by neutrinoless double-beta decay, charged-lepton flavor violation, and electroweak precision observables. The relatively large Yukawa couplings lead to sizable rates for charged lepton flavor violation processes, well within future experimental reach. The model could also successfully explain the W mass anomaly and provides viable fermionic or scalar dark matter candidates. © 2023, The Author(s).
Testing the effectiveness of the isoelectronic substitution principle through the transformation of aromatic osmathiophene derivatives into their inorganic analogues
(Royal Society of Chemistry, 2017) Vásquez-Espinal, Alejandro; Poater, Jordi; Solà, Miquel; Tiznado, William; Islas, Rafael
The objective of the current work is to evaluate the effectiveness of the isoelectronic substitution (IS) principle on a series of complexes with the general formula OsCl2(SX3H3)(PH3)2, where X3 represents the moieties CCC, CCB, CCN, CBN, CNB or NCB, formed by substitution of the carbon atoms in CCC by either the isoelectronic B- or N+ separately, or by both. The SX3H3 moiety forms, together with Os, an aromatic five-membered ring (5-MR) called osmathiophene. The preservation of stability and aromaticity in the resulting systems is used to indicate the effectiveness of the IS principle. The aromaticity of the proposed molecules is analyzed according to the magnetic (induced magnetic field (Bind)) and electronic (through the multicenter index (MCI)) criteria. In addition a chemical bonding analysis on selected species is performed by the adaptive natural density partitioning (AdNDP) method. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
The binuclear dual emitter [Br(CO)3Re(P⋯N)(N⋯P)Re(CO)3Br] (P⋯N): 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine, a new bridging: P, N -bidentate ligand resulting from the ring opening of tetrahydrofuran
(Royal Society of Chemistry, 2017) Saldías, Marianela; Manzur, Jorge; Palacios, Rodrigo E.; Gómez, María L.; Fuente, Julio De La; Günther, Germán; Pizarro, Nancy; Vega, Andrés
Lithium diphenylphosphide unexpectedly provokes the ring-opening of tetrahydrofuran (THF) and by reaction with 3,6-dichloropyridazine leads to the formation of the ligand 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine (P⋯N), which was isolated. The reaction of this ligand with the (Re(CO)3(THF)Br)2 dimer yields the novel complex [Br(CO)3Re(μ-3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine)2Re(CO)3Br] (BrRe(P⋯N)(N⋯P)ReBr), which was crystallized in the form of a chloroform solvate, (C46H40Br2Cl2N4O8P2Re2)·(CHCl3). The monoclinic crystal (P21/n) displays a bimetallic cage structure with a symmetry inversion centre in the middle of the rhenium to rhenium line. The molecule shows two oxidation signals occurring at +1.50 V and +1.76 V which were assigned to the ReI/ReII and ReII/ReIII metal-centered couples, respectively, while signals observed at -1.38 V and -1.68 V were assigned to ligand centered reductions. Experimental and DFT/TDDFT results indicate that the UV-Vis absorption maximum of BrRe(P⋯N)(N⋯P)ReBr occurring near 380 nm displays a metal to ligand charge transfer (MLCT) character, which is consistent with CV results. Upon excitation at this wavelength, a weak emission (Φem < 1 × 10-3) is observed around 580 nm (in dichloromethane) which decays with two distinct lifetimes τ1 and τ2 of 24 and 4.7 ns, respectively. The prevalence of non-radiative deactivation pathways is consistent with efficient internal conversion induced by the high conformational flexibility of the P⋯N ligand's long carbon chain. Measurements in a frozen solvent at 77 K, where vibrational deactivation is hindered, show intense emission associated with the 3MLCT state. These results demonstrate that BrRe(P⋯N)(N⋯P)ReBr preserves the dual emitting nature previously reported for the mononuclear complex RePNBr, with emission associated with and states. © 2017 The Royal Society of Chemistry.
A DFT study of the chemical reactivity of cimetidine A, C and D in the gas phase and in H2O, MeOH and EtOH solvents
(Serbian Chemical Society, 2017) Huizar, Luis Humberto Mendoza; Salgado-Morán, Guillermo; Cardona-Villada, Wilson; Pacheco, Alison Geraldo; Glossman-Mitnik, Daniel
In the present work, the chemical reactivity of cimetidine A, C and D in different solvents was analyzed through the evaluation of global and local DFT reactivity descriptors. In the gas, MeOH and EtOH phases, cimetidine A, C and D exhibit energy differences of 3-11 kcal∗∗ mol-1. However, in the aqueous phase, cimetidine A and D are approximately isoenergetic. The values of the hardness indicate that cimetidine A, C and D are more reactive in the presence of a solvent than in the gas phase. In addition, the results suggested that CimC and CimD are better nucleophiles that CimA. The values of the Fukui function suggest that the more reactive sites of CimA are not modified in the different solvents. In the case of CimC, the more reactive sites to electrophilic and free radical attack are located on the thioether sulfur. For CimD, the number and place of the electrophilic and free radical sites are independent of the solvent.

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