The continuous star formation history of a giant HII region in M101

We present results about the star formation process in the giant HII region NGC 5471 in the outskirts of M101. From resolved HST/WPFC2 photometry we find that star formation has been going for the last 70 Myr. We further compare previous results from integrated infrared-optical photometry with the stellar resolved CMD and we discuss the star formation properties of this region and its individual knots, as well as characterizing the different stellar content. This result has very important consequences in our understanding of the burst versus continuous star formation activity in spiral galaxies.Comment: 2 pages, 2 figures. Proceeding of the conference From Stars to Galaxies: Building the pieces to build up the Universe (Venice, Italy

Chemical Abundances of Planetary Nebulae in the Substructures of M31

We present deep spectroscopy of planetary nebulae (PNe) that are associated with the substructures of the Andromeda Galaxy (M31). The spectra were obtained with the OSIRIS spectrograph on the 10.4 m GTC. Seven targets were selected for the observations, three in the Northern Spur and four associated with the Giant Stream. The most distant target in our sample, with a rectified galactocentric distance >100 kpc, was the first PN discovered in the outer streams of M31. The [O III] 4363 auroral line was well detected in the spectra of all targets, enabling electron temperature determination. Ionic abundances are derived based on the [O III] temperatures, and elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon are estimated. The relatively low N/O and He/H ratios as well as abundance ratios of alpha-elements indicate that our target PNe might belong to populations as old as ~2 Gyr. Our PN sample, including the current seven and the previous three observed by Fang et al., have rather homogeneous oxygen abundances. The study of abundances and the spatial and kinematical properties of our sample leads to the tempting conclusion that their progenitors might belong to the same stellar population, which hints at a possibility that the Northern Spur and the Giant Stream have the same origin. This may be explained by the stellar orbit proposed by Merrett et al. Judging from the position and kinematics, we emphasize that M32 might be responsible for the two substructures. Deep spectroscopy of PNe in M32 will help to assess this hypothesis.Comment: Accepted for publication in the ApJ. 23 pages, including 13 figures and 7 table

Integration of in vitro and in silico Models Using Bayesian Optimization With an Application to Stochastic Modeling of Mesenchymal 3D Cell Migration

Cellular migration plays a crucial role in many aspects of life and development. In this paper, we propose a computational model of 3D migration that is solved by means of the tau-leaping algorithm and whose parameters have been calibrated using Bayesian optimization. Our main focus is two-fold: to optimize the numerical performance of the mechano-chemical model as well as to automate the calibration process of in silico models using Bayesian optimization. The presented mechano-chemical model allows us to simulate the stochastic behavior of our chemically reacting system in combination with mechanical constraints due to the surrounding collagen-based matrix. This numerical model has been used to simulate fibroblast migration. Moreover, we have performed in vitro analysis of migrating fibroblasts embedded in 3D collagen-based fibrous matrices (2 mg/ml). These in vitro experiments have been performed with the main objective of calibrating our model. Nine model parameters have been calibrated testing 300 different parametrizations using a completely automatic approach. Two competing evaluation metrics based on the Bhattacharyya coefficient have been defined in order to fit the model parameters. These metrics evaluate how accurately the in silico model is replicating in vitro measurements regarding the two main variables quantified in the experimental data (number of protrusions and the length of the longest protrusion). The selection of an optimal parametrization is based on the balance between the defined evaluation metrics. Results show how the calibrated model is able to predict the main features observed in the in vitro experiments

The Dependence of Galaxy Clustering on Stellar-mass Assembly History for LRGs

International audienceWe analyze the spectra of 300,000 luminous red galaxies (LRGs) with stellar masses $M_* \gtrsim 10^{11} M_{\odot}$ from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). By studying their star-formation histories, we find two main evolutionary paths converging into the same quiescent galaxy population at $z\sim0.55$. Fast-growing LRGs assemble $80\%$ of their stellar mass very early on ($z\sim5$), whereas slow-growing LRGs reach the same evolutionary state at $z\sim1.5$. Further investigation reveals that their clustering properties on scales of $\sim$1-30 Mpc are, at a high level of significance, also different. Fast-growing LRGs are found to be more strongly clustered and reside in overall denser large-scale structure environments than slow-growing systems, for a given stellar-mass threshold. Our results imply a dependence of clustering on stellar-mass assembly history (naturally connected to the mass-formation history of the corresponding halos) for a homogeneous population of similar mass and color, which constitutes a strong observational evidence of galaxy assembly bias

The EDGE-CALIFA survey: Variations in the molecular gas depletion time in local galaxies

We present results from the EDGE survey, a spatially resolved CO(1-0) follow-up to CALIFA, an optical Integral Field Unit survey of local galaxies. By combining the data products of EDGE and CALIFA, we study the variation in molecular gas depletion time (τdep) on kiloparsec scales in 52 galaxies. We divide each galaxy into two parts: The center, defined as the region within 0.1 R25, and the disk, defined as the region between 0.1 and 0.7 R25. We find that 14 galaxies show a shorter τdep (∼1 Gyr) in the center relative to that in the disk (τdep ∼ 2.4 Gyr), which means the central region in those galaxies is more efficient at forming stars per unit molecular gas mass. This finding implies that the centers with shorter τdep resemble the intermediate regime between galactic disks and starburst galaxies. Furthermore, the central drop in τdep is correlated with a central increase in the stellar surface density, suggesting that a shorter τdep is associated with molecular gas compression by the stellar gravitational potential. We argue that varying the CO-To-H2 conversion factor only exaggerates the central drop of τdep.Fil: Utomo, Dyas. University of California at Berkeley; Estados UnidosFil: Bolatto, Alberto. University of Maryland; Estados UnidosFil: Wong, Tony. University of Illinois at Urbana; Estados UnidosFil: Ostriker, Eve C.. University of Princeton; Estados UnidosFil: Blitz, Leo. University of California at Berkeley; Estados UnidosFil: Sanchez, Sebastian F.. Universidad Nacional Autónoma de México; MéxicoFil: Colombo, Dario. Max Planck Institute for Radio Astronomy; AlemaniaFil: Leroy, Adam K.. Ohio State University; Estados UnidosFil: Cao, Yixian. University of Illinois at Urbana; Estados UnidosFil: Dannerbauer, Helmut. Instituto de Astrofísica de Canarias; EspañaFil: Garcia Benito, Ruben. Instituto de Astrofísica de Andalucía; EspañaFil: Husemann, Bernd. Max Planck Institute für Astronomie; AlemaniaFil: Kalinova, Veselina. Max Planck Institute for Radio Astronomy; AlemaniaFil: Levy, Rebecca C.. University of Maryland; Estados UnidosFil: Mast, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Rosolowsky, Erik. University of Alberta; CanadáFil: Vogel, Stuart N.. University of Maryland; Estados Unido

Clinical research

Aorto-cavitary fistulous tract formation in infective endocarditis: clinical and echocardiographic features of 76 cases and risk factors for mortalit