Seminario de Astrofísica: “Dissecting the CGM: observational insights into the origin of PDLAs and simulated Arc-Tomography in TNG50”

El próximo martes 1 de julio, Francisco Urbina, de la Universidad de Chile, dictará el seminario “Dissecting the CGM: observational insights into the origin of PDLAs and simulated Arc-Tomography in TNG50” a las 11:00 horas en la Sala 208 del Instituto de Física, Campus Curauma, PUCV.

Compartimos el resumen de la presentación:

The gas reservoirs of galaxies and their interactions regulate galaxy evolution in a set of processes known as the baryon cycle. The venue where all these gas flows occur is known as the circumgalactic medium (CGM). Due to its diffuse nature, the CGM has been historically studied by means of QSO absorption spectra, providing only one line of sight per galaxy. This paradigm has radically changed in the last decade, where Integral Field Spectrographs in 8-10m class telescopes have been able to map the CGM both in emission, utilizing strong emission lines like Lyα, and in absorption, using giant gravitational arcs as background sources (technique known as gravitational-arc tomography). Taking advantage of this new transverse exploration of the diffuse gaseous environments of galaxies, the talk will focus on two fronts: first, using a compilation of PDLA-selected-QSOs observed with VLT/MUSE, characterize both the extended and compact Lyα emission, in order to constrain the origin of PDLAs and, thanks to the natural coronagraph offered by these proximate absorbers, to explore the inner regions of Lyα nebulae, offering some hints into the powering mechanism of Lyα nebulae. Second, utilizing TNG50 cosmological simulations, produce mock IFS-like absorption spectra to directly compare with the gravitational-arc tomography observations, studying the effect different spatial samplings have on different observables, comparing QSO and arc-tomography statistics, and computing the TNG50 cool CGM coherence length. 

Extendemos la invitación a la comunidad del Instituto de Física y público interesado a participar de este seminario.

Seminario de Astrofísica: “Quasars and everything in-between”

El próximo martes 17 de junio, el Dr. JK Krogager, de la Université de Lyon 1, dictará el seminario “Quasars and everything in-between” a las 11:00 horas en la Sala 208 del Instituto de Física, Campus Curauma, PUCV.

Compartimos el resumen de la presentación:

Quasars play an important, yet poorly understood, role in the evolution of galaxies. Current scenarios mainly invoke an evolutionary scenario in which quasars emerge through major merger events, starting out in a fully dust-obscured phase which later evolves to so-called “red quasars”. As the quasars destroy or blow out the obscuring dust, these then transition into the more typically known “blue quasar” phase.

However, this picture is limited by color-selection effects in all large-scale spectroscopic surveys of quasars.  Beyond their influence in shaping their host-galaxies, quasars also serve as important cosmic lighthouses enabling us to study intervening galaxies along the lines-of-sight through absorption spectroscopy. Again, the color-selection criteria imposed in quasar surveys affect our conclusions, this time caused by dust-reddening by the foreground, intervening absorption systems.

As these absorption systems are one of the main methods of studying the neutral gas reservoirs of galaxies, such selection biases can have strong implications for our understanding of galaxy evolution.

In this talk, I will focus on my current efforts towards the first color-unbiased quasar survey, the 4MOST-Gaia Purely Astrometric Quasar Survey, to be carried out with the upcoming 4MOST instrument at Paranal. I’ll emphasize its importance not only for understanding the evolution of quasars and their host-galaxies but also for gaining broader insights into the intervening absorption systems along the lines of sight. Lastly, I’ll give a short introduction to the 4MOST instrument and its planned arrival at the VISTA telescope this year.

Extendemos la invitación a la comunidad del Instituto de Física y público interesado a participar de este seminario.

Seminario de Astrofísica: “The Multi-Scale Interplay Between Dark and Luminous Matter”

Este martes 3 de junio, el Dr. Antonio D. Montero-Dorta, profesor de la Universidad Técnica Federico Santa María, presentará el seminario “The Multi-Scale Interplay Between Dark and Luminous Matter” a las 14:30 horas en la Sala 208 del Instituto de Física, Campus Curauma, PUCV.

Compartimos el abstract de la presentación:

The prevailing paradigm of galaxy formation posits that galaxies form within dark matter halos, which provide the potential wells needed for baryonic matter to accumulate, cool, and condense. Halos, in turn, are collapsed structures that originate from the high-density peaks of the underlying matter field. These objects are connected, albeit in a complex way, by their internal properties, clustering, and responses to the environment.

Characterizing the mapping between galaxies, halos, and the matter density field is essential not only for extracting cosmological information from galaxy surveys, but also for uncovering the physical mechanisms that shape galaxy evolution.

In this talk, I will present recent analytical and data-driven advances that enable a more detailed statistical dissection of halo and galaxy clustering in cosmological simulations, paying special attention to key physical phenomena such as assembly bias and the connection between clustering and the cosmic web. I will also discuss the observational detectability of these effects, along with the application of innovative techniques to data from upcoming large-scale galaxy surveys.

Extendemos la invitación a la comunidad del Instituto de Física y público interesado a participar de este seminario que busca aportar a la comprensión de la estructura del universo.

Seminario de Astrofísica: “The Effect of Massive Stellar Feedback Across the Carina Nebula Complex”

Seminario de Astrofísica en el IFIS. Este martes 20 de mayo, Constanza Norambuena, estudiante de Astronomía UC, presenta “The Effect of Massive Stellar Feedback Across the Carina Nebula Complex” desde las 14:30 horas en la Sala 208 del Instituto de Física PUCV, Campus Curauma. 

Compartimos el abstract de la presentación: 

Massive stars play a crucial role in affecting their surrounding environment, influencing star formation through radiative feedback. The Carina Nebula, located approximately 2.3 kpc away, serves as an excellent laboratory for studying these processes due to its large spatial extent and diverse star-forming environments.

In this project, we analyze ten selected regions within the nebula using ALMA Band 3 observations with the Atacama Compact Array and Total Power. Our focus is on molecular line emission (HCO⁺, HCN, CS) to investigate the physical and chemical conditions of the gas affected by massive stellar feedback.

This talk will focus on providing a brief overview of interferometry, the data processing steps, including imaging the interferometric observations using the tclean task in CASA, the combination of images from two different arrays (ACA 7-m and Total Power), and the various techniques that can be applied. Additionally, I will explain the generation of spectral cubes and the construction of moment maps to trace different gas structures.

Extendemos la invitación a la comunidad a participar de este seminario que busca aportar a la comprensión sobre las huellas que van dejando las estrellas masivas en su entorno interestelar.

Seminario de Astrofísica: “Simulation of the Impact of Jupiter-Type Rogue Planets on Circumstellar Disks”

Seminario de Astrofísica en el IFIS. Este martes 13 de mayo, Patricio Messen, estudiante del Magíster en Física de la Pontificia Universidad Católica de Valparaíso, presentará “Simulation of the Impact of Jupiter-Type Rogue Planets on Circumstellar Disks” a las 14:30 horas en la Sala 208 del Instituto de Física, Campus Curauma.

Compartimos el abstract de la presentación:

Circumstellar disks are structures of gas and dust that surround young stars during the early stages of their evolution. These disks are thought to be the sites of planet formation, and observations have revealed complex substructures with unclear origins, such as prominent spirals, low-density rings, and high-density regions where material accumulates.

In this work, we perform two-dimensional hydrodynamic simulations using the FARGO3D code, where we perturb a circumstellar disk with a Jupiter mass planet undergoing a coplanar flyby. We compare cases where the planet follows a prograde or retrograde trajectory. Simulations are carried out using two different equations of state: isothermal and adiabatic. The disk morphology varies significantly depending on the planet’s trajectory, and in all models, spiral-shaped density waves are generated and propagate throughout the disk.

In the retrograde case, two relatively close spiral arms form, while in the prograde scenario, two nearly symmetric spirals appear with respect to the central object. Under the isothermal condition, the spirals exhibit a more compact and well-defined structure compared to the adiabatic case, due to the absence of local temperature variations that would affect gas pressure. When local temperature variations are considered in the adiabatic models, we find that in the prograde case, the region where the spiral arms intersect experiences a significant temperature increase compared to the retrograde case.

To assess the observable differences between these scenarios, we adopt an approximation assuming dust perfectly coupled to the gas, and generate a synthetic spectral energy distribution (SED). This reveals that the temperature peak leads to an increase in the disk’s emitted flux. By evaluating viscous dissipation terms, we find that these events produce changes in bolometric luminosity below 1%, with prograde cases yielding the largest variation.

All simulated cases produce a low-density ring (gap) at approximately 8 AU from the central object. Uniquely in the prograde case with an adiabatic equation of state, a high-density ring forms just outside the gap, potentially acting as a dust trap and possibly triggering planetesimal formation. Finally, we perform a purely morphological comparison with Elias 2-27, a system that exhibits spiral arms with features resembling those of our simulated disks in the prograde scenario, which may provide insight into the origin of Elias 2-27’s observed morphology.

Extendemos la invitación a la comunidad a participar de este seminario que busca aportar al entendimiento de los procesos de formación planetaria.

Seminario de Astrofísica: “Bias Function and the Cosmic-Web connection”

Seminario de Astrofísica en el IFIS. Este martes 6 de mayo, Constanza Soto estudiante de Doctorado de Ciencias Físicas de la PUCV y UTFSM, presenta “Bias Function and the Cosmic-Web connection” desde las 14:30 en la Sala 208 del Instituto de Física PUCV.

Revisa el abstract de la presentación:

The spatial distribution of galaxies and dark matter haloes is not random and carries crucial information about the evolution of the universe. When referring to large-scale structure (LSS), we describe an inhomogeneous universe whose nature is studied through the evolution of perturbations in the density field. On larger scales, the evolution of these fluctuations, driven by the gravitational interaction of matter, gives rise to the formation of complex structures such as nodes, filaments, voids, and walls, collectively known as the cosmic web. Following this idea, the relation between the distribution of galaxies or dark matter haloes and the underlying matter density field is referred to as bias. The primary dependence of halo clustering is on halo mass, such that more massive haloes are more clustered than their less massive counterparts. However, secondary properties, at fixed halo mass, also influence clustering, leading to the so-called secondary bias. In this study, using the TNG300 hydrodynamical simulation, we employed an individual halo bias estimator, leveraging its advantages over traditional methods. With this estimator, we constructed the halo bias function, defined as the relation between the average individual bias per halo mass bin. By analyzing the halo bias function across different environments, we found that the trend varies for each environment, indicating that haloes located in the outskirts of nodes are highly clustered, in contrast to haloes in voids and walls. Similarly, linking to galaxy properties, we observed that haloes hosting red galaxies are more clustered, across all environments, than those hosting blue galaxies. Additionally, at low masses (log10(Mhost) < 12.5 h−1M⊙), red galaxies are significantly influenced by nearby massive haloes (log10(Mhost) > 13.5h−1M⊙)) within a radius of 5 h−1Mpc.