Astrofísica

La colaboración Event Horizon Telescope (EHT) observó por primera vez la imagen del agujero negro en el centro de nuestra galaxia, SgrA* en la banda de 1.3 mm (230 GHz). Las imágenes reconstruidas muestran el anillo de fotones con un diámetro de ~ 50-60 micro-segundos de arco consistente las predicciones de la relatividad general. El plasma en el disco de acreción orbitando el agujero negro es muy variable con tempos dinámicos de minutos, produciendo una variabilidad en las curvas de luz a diferentes frecuencias. En esta charla hablaremos del estudio de teorías de la gravedad usando la imagen de la sombra de un agujero negro como observable para probar differentes solutiones de agujeros negros, y de está manera acotar parámetros de la teoría o en su caso descartar algunos modelos

Stellar clusters are some of the most visible characteristics in galaxies.Studies have found that late-galaxies show two distinct populations of stellar clusters (e.g. Simanton et al. 2015a), an older component(globular clusters) and another younger one (open clusters). Studying The different populations of star clusters in galaxies can give us clues about the evolution and current state of galaxies (Pérez et al. 2013). In the framework of the hierarchical model of galaxy formation, the current state of galaxies is preceded by a great history of interactions and mergers of smaller elements. A Consequence of this model of galaxy formation is a continuous formation of stars, therefore stellar clusters of all ages in galaxies should be observed. The detection and observational studies of stellar clusters has focused in old clusters (e.g., Zepf & Ashman1993, Ashman & Zepf 1998, Brodie & Strader 2006 andreferences in) and in young clusters(e.g,Larsen & Richtler 1999, Bica et al. 2003). Recently, with the help of the HST, works about a new star clusters class has been done(e.g., Whitmore et al. 1999 (Antennae), Mayya et al. 2008 (M82),Santiago-Cortés et al. 2010 (M81) ), which have explored a new class of stellar clusters: super stellar clusters (SSC). These have characteristics similar to the globular clusters(mass, compactibility, etc.) and being the main candidates of an evolutionary state previous to the GCs they are essentially intermediate age clusters. In this seminar we will talk about the properties of the different stellar clusters.

High-mass stars play a critical role in shaping the evolution of galaxies, as they enrich the interstellar medium through stellar winds and supernovae. Understanding the formation of these stars is vital for refining models of galaxy formation and evolution. To shed light on the early stages of high-mass star formation, we can utilize interstellar masers, particularly the class II methanol masers at 6.7 GHz, which are exclusively observed in massive star-forming regions. Our study focuses on exploring the various aspects of massive star formation using 6.7 GHz methanol masers as indicators. Firstly, we investigate whether the maser luminosity correlates with the physical properties of the hosting clumps. This would provide insight into whether maser luminosity can serve as a tool to identify specific evolutionary phases in high mass star formation. Secondly, we employ maser emissions to study star formation on larger scales. Since 6.7 GHz masers are associated with early stages of high-mass star formation, searching for regions abundant in these maser detections, allows us to investigate relatively young star-forming sites. We analyse such a star forming region-Bubble N59- which harbours almost 8 6.7 GHz methanol masers, numerous compact HII regions, massive clumps, filaments, and bright rims. To characterize the N59 region comprehensively, we utilize multiwavelength data obtained from various surveys. Our molecular study uncovers two distinct molecular clouds in the region, which, although spatially close, occupy different regions in velocity space. We also propose that the feedback from the HII regions has led to the formation of prominent Bright Rimmed Clouds (BRC) within our region of interest.

Neutral atomic hydrogen (HI) fuels star formation and is the most extended component in galaxies. As such, it serves as a useful tool both for understanding galaxy evolution and probing the underlying dark matter distribution. The global H I in galaxies is readily observed through the 21-cm emission. Asymmetries introduced in these lines by local gravitational instabilities are expected to wash out in one or two galactic rotations, but observations indicate that notable asymmetries in H I lines are rather commonplace. Considering the crucial role of H I within galaxies, it is important to comprehend the origin of these asymmetries for devising a complete theory of galaxy evolution. Hydrodynamical simulations of galaxy formation conducted on cosmological scales are the ideal datasets for such investigations, owing to the self-consistent treatment of baryons and dark matter, diverse range of environments, and accurate tracking of systems over cosmic time. In this talk, I will present insights on H I line asymmetries as gleaned from the EAGLE simulation. I will begin by exploring the importance of instrumental aspects and line-of-sight for the inferred asymmetry when comparing with observations, and show that the observed asymmetries from the xGASS survey are in excellent agreement with EAGLE. Next, I will show how the asymmetries of central galaxies relate to gas flows, star formation activity, (gas and stellar) rotational support, and the assembly history and dynamical state of the host dark matter haloes. Lastly, I will show how environmental processing affects the asymmetries of satellite galaxies, including the impact of ram pressure, tidal stripping, and galaxy-galaxy interactions.