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Álgebras y fibrados de Clifford con aplicaciones
(Universidad de La Serena, 2012) Notte-Cuello, Eduardo
On monotone pseudocontractive operators and Krasnoselskij iterations in an ordered Hilbert space
(Springer Open, 2023-02-22) Jorquera Alvarez, Eduardo Daniel
The aim of this work is to establish fixed point results in ordered Hilbert spaces for monotone operators with a pseudocontractive property. We state monotone versions of Theorem 12 in [F. E. Browder, W. V. Petryshyn, Construction of fixed points of nonlinear mappings in Hilbert space, J. Math. Anal. Appl. 20 (1967), 197–228] and Theorem 2.1 in [Berinde, Vasile. Weak and strong convergence theorems for the Krasnoselskij iterative algorithm in the class of enriched strictly pseudocontractive operators, Annals of West University of Timisoara-Mathematics and Computer Science, vol. 56, no. 2, 2018, pp. 13–27], as well as, several related results. Further results, in Hilbert spaces without a partial order, are stated too.
CAPOS: the bulge Cluster APOgee Survey IV elemental abundances of the bulge globular cluster NGC 6558
(MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2023-10-20) González-Díaz, D.; Fernández-Trincado, J. G.; Villanova, S.; Geisler, D.; Barbuy, B.; Minniti, D.; Beers, T. C.; Bidin, C. M.; Mauro, F.; Muñoz, C.; Tang, B. T.; Soto, M.; Monachesi, A.; Lane, R. R.; Frelijj, H.
This study presents the results concerning six red giant stars members of the globular cluster NGC 6558. Our analysis utilized high-resolution near-infrared spectra obtained through the CAPOS initiative (the APOgee Surv e y of Clusters in the Galactic Bulge), which focuses on surv e ying clusters within the Galactic Bulge, as a component of the Apache Point Observatory Galactic Evolution Experiment II surv e y (APOGEE-2). We employ the Brussels Automatic Code for Characterizing High accUracy Spectra ( BACCHUS ) code to provide line-by-line elemental-abundances for Fe-peak (Fe, Ni), alpha-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z (Al), and the s-process element (Ce) for the four stars with high-signal-to-noise ratios. This is the first reliable measure of the CNO abundances for NGC 6558. Our analysis yields a mean metallicity for NGC 6558 of ([Fe/H]) = -1.15 +/- 0.08, with no evidence for a metallicity spread. We find a Solar Ni abundance, ([Ni/Fe]) similar to + 0.01, and a moderate enhancement of alpha-elements, ranging between + 0.16 and < + 0.42, and a slight enhancement of the s-process element ([Ce/Fe]) similar to + 0.19. We also found low levels of ([Al/Fe]) similar to + 0.09, but with a strong enrichment of nitrogen, [N/Fe] > + 0.99, along with a low level of carbon, [C/Fe] < -0.12. This behaviour of Nitrogen-Carbon is a typical chemical signature for the presence of multiple stellar populations in virtually all GCs; this is the first time that it is reported in NGC 6558. We also observed a remarkable consistency in the behaviour of all the chemical species compared to the other CAPOS bulge GCs of the same metallicity.
Integrated global assessment of the natural forest carbon potential
(2023-12-07) Mo, Lidong
Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2-5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellite-derived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151-363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.
Analysis of ground-sourced and satellite-derived models reveals a global forest carbon potential of 226 Gt outside agricultural and urban lands, with a difference of only 12% across these modelling approaches.
Pegasus IV: Discovery and Spectroscopic Confirmation of an Ultra-faint Dwarf Galaxy in the Constellation Pegasus
(IOP Publishing Ltd, 2023/01/01) Cerny, W., Simon, J. D., Li, T. S., Drlica-Wagner, A., Pace, A. B., Martinez-Vazquez, C. E., Riley, A. H., Mutlu-Pakdil, B., Mau, S., Ferguson, P. S., Erkal, D., Munoz, R. R., Bom, C. R., Carlin, J. L., Carollo, D., Choi, Y., Ji, A. P., Manwadkar, V., Martinez-Delgado, D., Miller, A. E., Noel, N. E. D., Sakowska, J. D., Sand, D. J., Stringfellow, G. S., Tollerud, E. J., Vivas, A. K., Carballo-Bello, J. A., Hernandez-Lang, D., James, D. J., Nidever, D. L., Castellon, J. L. Nilo, Olsen, K. A. G., Zenteno, A.
We report the discovery of Pegasus IV, an ultra-faint dwarf galaxy found in archival data from the Dark Energy Camera processed by the DECam Local Volume Exploration Survey. Pegasus IV is a compact, ultra-faint stellar system ( = -r(1/2) 41(-6)(+8) pc, M-V = -4.25 +/- 0.2 mag) located at a heliocentric distance of 90(-6)(+4) kpc. Based on spectra of seven nonvariable member stars observed with Magellan/IMACS, we confidently resolve Pegasus IV's velocity dispersion, measuring s = sigma(v) 3.3(-1.1)(+1.7) km s(-1) (after excluding three velocity outliers), this implies a mass-to-light ratio of M1/2LV ,(1/2)=167(-99)(+224) M-?/L-? for the system. From the five stars with the highest signal-to-noise spectra, we also measure a systemic metallicity of [Fe/H] = -2.63(-0.30)(+0.26) dex, making Pegasus IV one of the most metal-poor ultra-faint dwarfs. We tentatively resolve a nonzero metallicity dispersion for the system. These measurements provide strong evidence that Pegasus IV is a dark-matter-dominated dwarf galaxy, rather than a star cluster. We measure Pegasus IV's proper motion using data from Gaia Early Data Release 3, finding (mu(alpha*, mu delta)) = (0.33 +/- 0.07, -0.21 +/- 0.08) mas yr(-1). When combined with our measured systemic velocity, this proper motion suggests that Pegasus IV is on an elliptical, retrograde orbit, and is currently near its orbital apocenter. Lastly, we identify three potential RR Lyrae variable stars within Pegasus IV, including one candidate member located more than 10 half-light radii away from the system's centroid. The discovery of yet another ultra-faint dwarf galaxy strongly suggests that the census of Milky Way satellites is still incomplete, even within 100 kpc.
Bulge-disc decomposition of the Hydra cluster galaxies in 12 bands
(OXFORD UNIV PRESS, 2023/01/01) Lima-Dias, Ciria, Monachesi, Antonela, Torres-Flores, Sergio, Cortesi, Arianna, Hernandez-Lang, Daniel, P. Montaguth, Gissel, Jimenez-Teja, Yolanda, Panda, Swayamtrupta, Menendez-Delmestre, Karin, Goncalves, Thiago S., Mendez-Hernandez, Hugo, Telles, Eduardo, Dimauro, Paola, Bom, Clecio R., de Oliveira, Claudia Mendes, Kanaan, Antonio, Ribeiro, Tiago, Schoenell, William
When a galaxy falls into a cluster, its outermost parts are the most affected by the environment. In this paper, we are interested in studying the influence of a dense environment on different galaxy's components to better understand how this affects the evolution of galaxies. We use, as laboratory for this study, the Hydra cluster which is close to virialization, yet it still shows evidence of substructures. We present a multiwavelength bulge-disc decomposition performed simultaneously in 12 bands from S-PLUS (Southern Photometric Local Universe Survey) data for 52 galaxies brighter than m(r) = 16. We model the galaxies with a Sersic profile for the bulge and an exponential profile for the disc. We find that the smaller, more compact, and bulge-dominated galaxies tend to exhibit a redder colour at a fixed stellar mass. This suggests that the same mechanisms (ram-pressure and tidal stripping) that are causing the compaction in these galaxies are also causing them to stop forming stars. The bulge size is unrelated to the galaxy's stellar mass, while the disc size increases with greater stellar mass, indicating the dominant role of the disc in the overall galaxy mass-size relation found. Furthermore, our analysis of the environment unveils that quenched galaxies are prevalent in regions likely associated with substructures. However, these areas also harbour a minority of star-forming galaxies, primarily resulting from galaxy interactions. Lastly, we find that similar to 37 per cent of the galaxies exhibit bulges that are bluer than their discs, indicative of an outside-in quenching process in this type of dense environments.
Pre-main-sequence Brackett Emitters in the APOGEE DR17 Catalog: Line Strengths and Physical Properties of Accretion Columns
(IOP Publishing Ltd, 2023/01/01) Campbell, Hunter, Khilfeh, Elliott, Covey, Kevin R., Kounkel, Marina, Ballantyne, Richard, Corey, Sabrina, Roman-Zuniga, Carlos G., Hernandez, Jesus, Martinez, Ezequiel Manzo, Ramirez, Karla Pena, Roman-Lopes, Alexandre, Stassun, Keivan G., Stringfellow, Guy S., Borissova, Jura, Chojnowski, S. Drew, Ramirez-Preciado, Valeria, Kim, Jinyoung Serena, Serna, Javier, Stutz, Amelia M., Lopez-Valdivia, Ricardo, Suarez, Genaro, Ybarra, Jason E., Longa-Pena, Penelope, Fernandez-Trincado, Jose G.
Very young (t less than or similar to 10 Myr) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar disks to the surface of the star. Upon impacting the stellar surface, the shocked gas recombines and emits hydrogen spectral lines. To characterize the density and temperature of the gas within these accretion streams, we measure equivalent widths of Brackett (Br) 11-20 emission lines detected in 1101 APOGEE spectra of 326 likely pre-main-sequence accretors. For sources with multiple observations, we measure median epoch-to-epoch line strength variations of 10% in Br11 and 20% in Br20. We also fit the measured line ratios to predictions of radiative transfer models by Kwan & Fischer. We find characteristic best-fit electron densities of n ( e ) = 10(11)-10(12) cm(-3), and excitation temperatures that are inversely correlated with electron density (from T similar to 5000 K for n ( e ) similar to 10(12) cm(-3) to T similar to 12,500 K at n ( e ) similar to 10(11) cm(-3)). These physical parameters are in good agreement with predictions from modeling of accretion streams that account for the hydrodynamics and radiative transfer within the accretion stream. We also present a supplementary catalog of line measurements from 9733 spectra of 4255 Brackett emission-line sources in the APOGEE Data Release 17 data set.
The isolated elliptical galaxy NGC 5812-MOND or dark matter?
(WILEY-V C H VERLAG GMBH, 2023/01/01) Richtler, Tom, Salinas, Ricardo, Lane, Richard, Hilker, Michael
There exist isolated elliptical galaxies, whose dynamics can be modeled without resorting to dark matter or MOND, for example, NGC 7507. Such objects lack understanding within the current framework of galaxy formation. The isolated elliptical NGC 5812 is another object to investigate a possible role of isolation. We use globular clusters (GCs) and the galaxy light itself as dynamical tracers to constrain its mass profile. We employ Gemini/GMOS mask spectroscopy, apply the GMOS reduction procedures provided within IRAF, measure GC velocities by cross correlation methods and extract the line-of-sight kinematics of galaxy spectra using the tool pPXF. We identify 28 GCs with an outermost galactocentric distance of 20 kpc, for which velocities could be obtained. Furthermore, 16 spectra of the integrated galaxy light out to 6 kpc have been used to model the central kinematics. These spectra provide evidence for a disturbed velocity field, which is plausible given the disturbed morphology of the galaxy. We construct spherical Jeans models for the galaxy light and apply tracer mass estimators for the globular clusters. With the assumptions inherent to the mass estimators, MOND is compatible with the mass out to 20 kpc. However, a dark matter free galaxy is not excluded, given the uncertainties related to a possible nonsphericity and a possible nonequilibrium state. We find one globular cluster with an estimated mass of 1.6x107M circle dot$$ 1.6times 1{0}<^>7{M}_{odot } $$, the first Ultra Compact Dwarf in an isolated elliptical. We put NGC 5812 into the general context of dark matter or alternative ideas in elliptical galaxies. The case for a MONDian phenomenology also among early-type galaxies has become so strong that deviating cases appear astrophysically more interesting than agreements. The baryonic Tully Fisher relation (BTFR) as predicted by MOND is observed in some samples of early-type galaxies, in others not. However, in cases of galaxies that deviate from the MONDian prediction, data quality and data completeness are often problematic.
The Forward Physics Facility at the High-Luminosity LHC
(IOP Publishing Ltd, 2023/01/01) Feng Jonathan L.; Kling Felix; Reno Mary Hall; Rojo Juan; Soldin Dennis; Anchordoqui Luis A.; Boyd Jamie; Ismail Ahmed; Harland-Lang Lucian; Kelly Kevin J.; Pandey Vishvas; Trojanowski Sebastian; Tsai Yu-Dai; Alameddine Jean-Marco; Araki Takeshi; Ariga Akitaka; Ariga Tomoko; Asai Kento; Bacchetta Alessandro; Balazs Kincso; Barr Alan J.; Battistin Michele; Bian Jianming; Bertone Caterina; Bai Weidong; Bakhti Pouya; Balantekin A. Baha; Barman Basabendu; Batell Brian; Bauer Martin; Bauer Brian; Becker Mathias; Berlin Asher; Bertuzzo Enrico; Bhattacharya Atri; Bonvini Marco; Boogert Stewart T.; Boyarsky Alexey; Bramante Joseph; Brdar Vedran
High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.
Long-lived heavy neutral leptons from mesons in effective field theory
(SPRINGER, 2023/01/04) Beltran Rebeca; Cottin Giovanna; Carlos Helo Juan; Hirsch Martin; Titov Arsenii; Wang Zeren Simon
In the framework of the low-energy effective field theory of the Standard Model extended with heavy neutral leptons (HNLs), we calculate the production rates of HNLs from meson decays triggered by dimension-six operators. We consider both lepton number-conserving and lepton-number-violating four-fermion operators involving either a pair of HNLs or a single HNL. Assuming that HNLs are long-lived, we perform simulations and investigate the reach of the proposed far detectors at the high-luminosity LHC to (i) active-heavy neutrino mixing and (ii) the Wilson coefficients associated with the effective operators, for HNL masses below the mass of the B-meson. We further convert the latter to the associated new-physics scales. Our results show that scales in excess of hundreds of TeV and the active-heavy mixing squared as small as 10(-15 )can be probed by these experiments.
Colour and infall time distributions of satellite galaxies in simulated Milky-Way analogues
(OXFORD UNIV PRESS, 2023/01/09) Pan, Yue, Simpson, Christine M., Kravtsov, Andrey, Gomez, Facundo A., Grand, Robert J. J., Marinacci, Federico, Pakmor, Rudiger, Manwadkar, Viraj, Esmerian, Clarke J.
We use the Auriga simulations to probe different satellite quenching mechanisms operating at different mass scales (10(5) M-theta ? M * < 10(11) M ((R))) in Milky Way-like hosts. Our goal is to understand the origin of the satellite colour distribution and star-forming properties in both observations and simulations. We find that the satellite populations in the Auriga simulations, which was originally designed to model Milky Way-like host galaxies, resemble the populations in the Exploration of Local VolumE Satellites (ELVES) Surv e y and the Satellites Around Galactic Analogs (SAGA) survey in their luminosity function in the luminosity range -12 ? M-V ? -15 and resemble ELVES in their quenched fraction and colour-magnitude distribution in the luminosity range -12 ? M-g ? -15. We find that satellites transition from blue colours to red colours at the luminosity range -15 ? Mg ? -12 in both the simulations and observations and we show that this shift is driven by environmental effects in the simulations. We demonstrate also that the colour distribution in both simulations and observations can be decomposed into two statistically distinct populations based on their morphological type or star-forming status that are statistically distinct. In the simulations, these two populations also have statistically distinct infall time distributions. The comparison presented here seems to indicate that this tension is resolved by the impro v ed target selection of ELVES, but there are still tensions in understanding the colours of faint galaxies, of which ELVES appears to have a significant population of faint blue satellites not reco v ered in Auriga.
Spatially resolved properties of the ionized gas in the H ii galaxy J084220+115000
(OXFORD UNIV PRESS, 2023/01/09) Fernandez-Arenas, D., Carrasco, E., Terlevich, R., Terlevich, E., Amorin, R., Bresolin, F., Chavez, R., Gonzalez-Moran, A. L., Rosa-Gonzalez, D., Mayya, Y. D., Vega, O., Zaragoza-Cardiel, J., Mendez-Abreu, J., Izazaga-Perez, R., Gil de Paz, A., Gallego, J., Iglesias-Paramo, J., Garcia-Vargas, M. L., Gomez-Alvarez, P., Castillo-Morales, A., Cardiel, N., Pascual, S., Perez-Calpena, A.
We present a spatially resolved spectroscopic study for the metal poor H ii galaxy J084220+115000 using MEGARA Integral Field Unit observations at the Gran Telescopio Canarias. We estimated the gas metallicity using the direct method for oxygen, nitrogen, and helium and found a mean value of 12 + log (O/H) = 8.03 +/- 0.06, and integrated electron density and temperature of similar to 161 cm(-3) and similar to 15400 K, respectively. The metallicity distribution shows a large range of Delta(O/H) = 0.72 dex between the minimum and maximum (7.69 +/- 0.06 and 8.42 +/- 0.05) values, unusual in a dwarf star-forming galaxy. We derived an integrated log (N/O) ratio of -1.51 +/- 0.05 and found that both N/O and O/H correspond to a primary production of metals. Spatially resolved maps indicate that the gas appears to be photoionized by massive stars according to the diagnostic line ratios. Between the possible mechanisms to explain the starburst activity and the large variation of oxygen abundance in this galaxy, our data support a possible scenario where we are witnessing an ongoing interaction triggering multiple star-forming regions localized in two dominant clumps.
Ca triplet metallicities and velocities for 12 globular clusters toward the galactic bulge
(EDP SCIENCES S A, 2023/01/20) Geisler, D., Parisi, M. C., Dias, B., Villanova, S., Mauro, F., Saviane, I., Cohen, R. E., Moni Bidin, C., Minniti, D.
Context. Globular clusters (GCs) are excellent tracers of the formation and early evolution of the Milky Way. The bulge GCs (BGCs) are particularly important because they can reveal vital information about the oldest in situ component of the Milky Way.Aims. Our aim is to derive the mean metallicities and radial velocities for 13 GCs that lie toward the bulge and are generally associated with this component. This region is observationally challenging because of high extinction and stellar density, which hampers optical studies of these and similar BGCs, making most previous determinations of these parameters quite uncertain.Methods. We used near-infrared low-resolution spectroscopy with the FORS2 instrument on the VLT to measure the wavelengths and equivalent widths of the CaII triplet (CaT) lines for a number of stars per cluster. We derived radial velocities, ascertained membership, and applied known calibrations to determine metallicities for cluster members, for a mean of 11 members per cluster. Unfortunately, one of our targets, VVV-GC002, which is the closest GC to the Galactic center, turned out not to have any members in our sample.Results. We derive mean cluster RV values to 3 km s(-1), and mean metallicities to 0.05 dex. We find general good agreement with previous determinations for both metallicity and velocity. On average, our metallicities are 0.07 dex more metal-rich than those of Harris (2010, arXiv:1012.3224), with a standard deviation of the difference of 0.25 dex. Our sample has metallicities between -0.21 and -1.64, and the values are distributed between the traditional metal-rich BGC peak near [Fe/H] -0.5 and a more metal-poor peak around [Fe/H] -1.1, which has recently been identified. These latter are candidates for the oldest GCs in the Galaxy, if blue horizontal branches are present, and include BH 261, NGC 6401, NGC 6540, NGC 6642, and Terzan 9. Finally, Terzan 10 is even more metal-poor. However, dynamically, Terzan 10 is likely an intruder from the halo, possibly associated with the Gaia-Enceladus or Kraken accretion events. Terzan 10 is also confirmed as an Oosterhoff type II GC based on our results.Conclusions. The CaT technique is an excellent method for deriving mean metallicities and velocities for heavily obscured GCs. Our sample provides reliable mean values for these two key properties via spectroscopy of a significant number of members per cluster for this important yet previously poorly studied sample of BGCs. We emphasize that the more metal-poor GCs are excellent candidates for being ancient relics of bulge formation. The lone halo intruder in our sample, Terzan 10, is conspicuous for also having by far the lowest metallicity, and casts doubt on the possibility of any bona fide BGCs at metallicities below about -1.5.
Quasinormal modes of a charged scalar field in Ernst black holes
(SPRINGER, 2023/01/25) Becar Ramon; Gonzalez P. A.; Vasquez Yerko
We consider the propagation of a charged massive scalar field in the background of a four-dimensional Ernst black hole and study its stability analyzing the quasinormal modes (QNMs), which are calculated using the semi-analytical Wentzel-Kramers-Brillouin method and numerically using the continued fraction method. We mainly find that for a scalar field mass less than a critical mass, the decay rate of the QNMs decreases when the harmonic angular number l increases; and for a scalar field mass greater than the critical mass, the behavior is inverted, i.e., the longest-lived modes are always the ones with the lowest angular number recovering the standard behavior. Also, we find a critical value of the external magnetic field, as well as a critical value of the scalar field charge that exhibits the same behavior with respect to the angular harmonic numbers. In addition, we show that the spacetime allows stable quasibound states, and we observe a splitting of the spectrum due to the Zeeman effect. Finally, we show that the unstable null geodesic in the equatorial plane is connected with the QNMs when the azimuthal quantum number satisfies m= & PLUSMN;l in the eikonal limit.
Dusty Starbursts Masquerading as Ultra-high Redshift Galaxies in JWST CEERS Observations
(IOP Publishing Ltd, 2023/02/01) Zavala, Jorge A., Buat, Veronique, Casey, Caitlin M., Finkelstein, Steven L., Burgarella, Denis, Bagley, Micaela B., Ciesla, Laure, Daddi, Emanuele, Dickinson, Mark, Ferguson, Henry C., Franco, Maximilien, Jimenez-Andrade, E. F., Kartaltepe, Jeyhan S., Koekemoer, Anton M., Le Bail, Aurelien, Murphy, E. J., Papovich, Casey, Tacchella, Sandro, Wilkins, Stephen M., Aretxaga, Itziar, Behroozi, Peter, Champagne, Jaclyn B., Fontana, Adriano, Giavalisco, Mauro, Grazian, Andrea, Grogin, Norman A., Kewley, Lisa J., Kocevski, Dale D., Kirkpatrick, Allison, Lotz, Jennifer M., Pentericci, Laura, Perez-Gonzalez, Pablo G., Pirzkal, Nor, Ravindranath, Swara, Somerville, Rachel S., Trump, Jonathan R., Yang, Guang, Yung, L. Y. Aaron, Almaini, Omar, Amorin, Ricardo O., Annunziatella, Marianna, Haro, Pablo Arrabal, Backhaus, Bren E., Barro, Guillermo, Bell, Eric F., Bhatawdekar, Rachana, Bisigello, Laura, Buitrago, Fernando, Calabro, Antonello, Castellano, Marco, Ortiz, Oscar A. Chavez, Chworowsky, Katherine, Cleri, Nikko J., Cohen, Seth H., Cole, Justin W., Cooke, Kevin C., Cooper, M. C., Cooray, Asantha R., Costantin, Luca, Cox, Isabella G., Croton, Darren, Dave, Romeel, de la Vega, Alexander, Dekel, Avishai, Elbaz, David, Estrada-Carpenter, Vicente, Fernandez, Vital, Finkelstein, Keely D., Freundlich, Jonathan, Fujimoto, Seiji, Garcia-Argumanez, Angela, Gardner, Jonathan P., Gawiser, Eric, Gomez-Guijarro, Carlos, Guo, Yuchen, Hamilton, Timothy S., Hathi, Nimish P., Holwerda, Benne W., Hirschmann, Michaela, Huertas-Company, Marc, Hutchison, Taylor A., Iyer, Kartheik G., Jaskot, Anne E., Jha, Saurabh W., Jogee, Shardha, Juneau, Stephanie, Jung, Intae, Kassin, Susan A., Kurczynski, Peter, Larson, Rebecca L., Leung, Gene C. K., Long, Arianna S., Lucas, Ray A., Magnelli, Benjamin, Mantha, Kameswara Bharadwaj, Matharu, Jasleen, McGrath, Elizabeth J., McIntosh, Daniel H., Medrano, Aubrey, Merlin, Emiliano, Mobasher, Bahram, Morales, Alexa M., Newman, Jeffrey A., Nicholls, David C., Pandya, Viraj, Rafelski, Marc, Ronayne, Kaila, Rose, Caitlin, Ryan, Russell E., Santini, Paola, Seille, Lise-Marie, Shah, Ekta A., Shen, Lu, Simons, Raymond C., Snyder, Gregory F., Stanway, Elizabeth R., Straughn, Amber N., Teplitz, Harry, I, Vanderhoof, Brittany N., Vega-Ferrero, Jesus, Wang, Weichen, Weiner, Benjamin J., Willmer, Christopher N. A., Wuyts, Stijn
Lyman-break galaxy (LBG) candidates at z greater than or similar to 10 are rapidly being identified in James Webb Space Telescope (JWST)/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of rest-frame UV photons, these sources are expected to drop out in the bluer filters while being well detected in redder filters. However, here we show that dust-enshrouded star-forming galaxies at lower redshifts (z less than or similar to 7) may also mimic the near-infrared (near-IR) colors of z > 10 LBGs, representing potential contaminants in LBG candidate samples. First, we analyze CEERS-DSFG-1, a NIRCam dropout undetected in the F115W and F150W filters but detected at longer wavelengths. Combining the JWST data with (sub)millimeter constraints, including deep NOEMA interferometric observations, we show that this source is a dusty star-forming galaxy (DSFG) at z approximate to 5.1. We also present a tentative 2.6 sigma SCUBA-2 detection at 850 mu m around a recently identified z approximate to 16 LBG candidate in the same field and show that, if the emission is real and associated with this candidate, the available photometry is consistent with a z similar to 5 dusty galaxy with strong nebular emission lines despite its blue near-IR colors. Further observations on this candidate are imperative to mitigate the low confidence of this tentative submillimeter emission and its positional uncertainty. Our analysis shows that robust (sub)millimeter detections of NIRCam dropout galaxies likely imply z similar to 4-6 redshift solutions, where the observed near-IR break would be the result of a strong rest-frame optical Balmer break combined with high dust attenuation and strong nebular line emission, rather than the rest-frame UV Lyman break. This provides evidence that DSFGs may contaminate searches for ultra-high redshift LBG candidates from JWST observations.
Stellar Properties for a Comprehensive Collection of Star-forming Regions in the SDSS APOGEE-2 Survey
(IOP Publishing Ltd, 2023/02/01) Roman-Zuniga, Carlos G., Kounkel, Marina, Hernandez, Jesus, Pena Ramirez, Karla, Lopez-Valdivia, Ricardo, Covey, Kevin R., Stutz, Amelia M., Roman-Lopes, Alexandre, Campbell, Hunter, Khilfeh, Elliott, Tapia, Mauricio, Stringfellow, Guy S., Jose Downes, Juan, Stassun, Keivan G., Minniti, Dante, Bayo, Amelia, Kim, Jinyoung Serena, Suarez, Genaro, Ybarra, Jason E., Fernandez-Trincado, Jose G., Longa-Pena, Penelope, Ramirez-Preciado, Valeria, Serna, Javier, Lane, Richard R., Garcia-Hernandez, D. A., Beaton, Rachael L., Bizyaev, Dmitry, Pan, Kaike
The Sloan Digital Sky Survey IV APOGEE-2 primary science goal was to observe red giant stars throughout the Galaxy to study its dynamics, morphology, and chemical evolution. The APOGEE instrument, a high-resolution 300fiber H-band (1.55-1.71 mu m) spectrograph, is also ideal to study other stellar populations in the Galaxy, among which are a number of star-forming regions and young open clusters. We present the results of the determination of six stellar properties (Teff, log g, [Fe/H], L/L-circle dot, M/M-circle dot, and age) for a sample that is composed of 3360 young stars, of subsolar to supersolar types, in 16 Galactic star formation and young open cluster regions. Those sources were selected by using a clustering method that removes most of the field contamination. Samples were also refined by removing targets affected by various systematic effects of the parameter determination. The final samples are presented in a comprehensive catalog that includes all six estimated parameters. This overview study also includes parameter spatial distribution maps for all regions and Hertzsprung-Russell (log L/L-circle dot vs. T-eff) diagrams. This study serves as a guide for detailed studies on individual regions and paves the way for the future studies on the global properties of stars in the pre-main-sequence phase of stellar evolution using more robust samples.
The Low-redshift Lyman Continuum Survey: Optically Thin and Thick Mg ii Lines as Probes of Lyman Continuum Escape
(IOP Publishing Ltd, 2023/02/01) Xu, Xinfeng, Henry, Alaina, Heckman, Timothy, Chisholm, John, Marques-Chaves, Rui, Leclercq, Floriane, Berg, Danielle A., Jaskot, Anne, Schaerer, Daniel, Worseck, Gabor, Amorin, Ricardo O., Atek, Hakim, Hayes, Matthew, Ji, Zhiyuan, Ostlin, Goran, Saldana-Lopez, Alberto, Thuan, Trinh
The Mg ii lambda lambda 2796, 2803 doublet has been suggested as a useful indirect indicator for the escape of Ly alpha and Lyman continuum (LyC) photons in local star-forming galaxies. However, studies to date have focused on small samples of galaxies with strong Mg ii or strong LyC emission. Here, we present the first study of Mg ii to probe a large dynamic range of galaxy properties, using newly obtained high-signal-to-noise, moderate-resolution spectra of Mg ii, for a sample of 34 galaxies selected from the Low-redshift Lyman Continuum Survey. We show that the galaxies in our sample have Mg ii profiles ranging from strong emission to P-Cygni profiles to pure absorption. We find that there is a significant trend (with a possibility of spurious correlations of similar to 2%) that galaxies that are detected as strong LyC emitters (LCEs) show larger equivalent widths of Mg ii emission, while non-LCEs tend to show evidence of more scattering and absorption features in Mg ii. We then find that Mg ii strongly correlates with Ly alpha in both equivalent width and escape fraction, regardless of whether emission or absorption dominates the Mg ii profiles. Furthermore, we show that, for galaxies that are categorized as Mg ii emitters, one can use the information of Mg ii, metallicity, and dust to estimate the escape fraction of LyC within a factor of similar to 3. These findings confirm that Mg ii lines can be used as a tool for selecting galaxies as LCEs and thus serve as an indirect indicator for the escape of Ly alpha and LyC.
Elemental abundance differences in the massive planet-hosting wide binary HD 196067-68
(OXFORD UNIV PRESS, 2023/02/01) Flores, M., Yana Galarza, J., Miquelarena, P., Saffe, C., Jaque Arancibia, M., Ibanez Bustos, R., V, Jofre, E., Alacoria, J., Gunella, F.
It has been suggested that small chemical anomalies observed in planet-hosting wide binary systems could be due to planet signatures, where the role of the planetary mass is still unknown. We search for a possible planet signature by analysing the T-C trends in the remarkable binary system HD 196067-HD 196068. At the moment, only HD 196067 is known to host a planet that is near the brown dwarf regime. We take advantage of the strong physical similarity between both stars, which is crucial to achieving the highest possible precision in stellar parameters and elemental chemical abundances. This system gives us a unique opportunity to explore whether a possible depletion of refractories in a binary system could be inhibited by the presence of a massive planet. We performed a line-by-line chemical differential study, employing the non-solar-scaled opacities, in order to reach the highest precision in the calculations. After differentially comparing both stars, HD 196067 displays a clear deficiency in refractory elements in the T-C plane, a lower iron content (0.051 dex), and also a lower Li I content (0.14 dex) than its companion. In addition, the differential abundances reveal a T-C trend. These targets represent the first cases of an abundance difference around a binary system hosting a super-Jupiter. Although we explored several scenarios to explain the chemical anomalies, none of them can be entirely ruled out. Additional monitoring of the system as well as studies of larger sample of wide binary systems hosting massive planets are needed to better understand the chemical abundance trend observed in HD 196067-68.
Multiple Populations in Low-mass Globular Clusters: Eridanus
(IOP Publishing Ltd, 2023/02/01) Wang, Yue, Tang, Baitian, Li, Chengyuan, Baumgardt, Holger, Munoz, Ricardo R., Fernandez-Trincado, Jose G., Geisler, Doug, Fang, Yuanqing
Multiple populations (MPs), characterized by variations in light elemental abundances, have been found in stellar clusters in the Milky Way, Magellanic Clouds, as well as several other dwarf galaxies. Based on a large number of observations, mass has been suggested to be a key parameter affecting the presence and appearance of MPs in stellar clusters. To further investigate the existence of MPs in low-mass clusters and explore the mass threshold for the formation of MPs, we carried out a project studying the composition of the stellar population in several lowmass Galactic globular clusters. Here we present our study on the cluster Eridanus. With blue-UV low-resolution spectra obtained with the OSIRIS/Multi-object spectrograph on the Gran Telescopio Canarias, we computed the spectral indices of CH and CN for a sample of giant stars and derived their carbon and nitrogen abundances using model spectra. A significant dispersion in the initial surface abundance of nitrogen was found in the sample, indicating the existence of MPs in Eridanus. Inspecting the age-initial mass distribution of in situ clusters with MPs, we find a slight trend that initial mass increases with increasing age, and the lowest initial masses of logM(initial) similar to 4.98 and 5.26 are found at the young and old end, respectively, which might provide a rough reference for the mass threshold for clusters to form MPs. However, more observations of clusters with low initial masses are still necessary before any firm conclusion can be drawn.
Long-lived heavy neutral leptons with a displaced shower signature at CMS
(SPRINGER, 2023/02/01) Cottin Giovanna; Helo Juan Carlos; Hirsch Martin; Pena Cristian; Wang Christina; Xie Si
We study the LHC discovery potential in the search for heavy neutral leptons (HNL) with a new signature: a displaced shower in the CMS muon detector, giving rise to a large cluster of hits forming a displaced shower. A new Delphes module is used to model the CMS detector response for such displaced decays. We reinterpret a dedicated CMS search for neutral long-lived particles decaying in the CMS muon endcap detectors for the minimal HNL scenario. We demonstrate that this new strategy is particularly sensitive to active-sterile mixings with tau leptons, due to hadronic tau decays. HNL masses between similar to 1-6 GeV can be accessed for mixings as low as vertical bar V-tau N vertical bar(2) similar to 10(-7), probing unique regions of parameter space in the tau sector.