Calendar
Registration
Monday 08:30 – 08:50Welcome words
Monday 08:50 – 09:00Cecilia Mateu
Universidad de la República, UruguayMonday 09:00 – 09:50
Keeping track of the Galactic system of stellar streams
Stellar streams are to dynamics as stellar clusters are to stellar evolution: relatively “simple” systems of stars with a common origin whose common properties can be used to rewind evolutionary or dynamical processes much harder to disentangle in the Galactic field. A stellar stream is formed as stars are stripped from a dwarf galaxy or globular cluster by the Milky Way’s tidal forces, creating a fossil record of accretion that is best preserved in the halo, where streams are long lived. Unearthing this record is essential to reconstructing the Galaxy’s accretion history, and modeling its dynamics is key to constrain the distribution of dark matter at the scales of the Galaxy and its satellites. In this contribution, I will showcase the galstreams library, an effort to collate the information in the literature for the nearly one hundred stellar streams known in the Milky Way, and use it to provide an ensemble view of the Galactic system of stellar streams’s properties, its current observational biases, and results inspired by recent discoveries made possible by the Gaia mission.
Santiago Collazo
Facultad de Ciencias Astronómicas y Geofísicas de La PlataMonday 09:50 – 10:15
Sagittarius dSph stellar stream under a fermionic dark matter halo
The study of stellar streams allows us to constrain the mass distribution of galaxies. In this work, we fit proper motion observables of the Sagittarius dwarf spheroidal stellar stream, the largest tidal debris of our Galaxy. This is done assuming the Milky Way’s dark halo is a self-gravitating system of fermions, which results from a maximum entropy production principle. It was shown, in recent works, that it is a good, non-empirical model for the dark component of galaxies. Modelling the disruption of a satellite in its orbit around a host with an elementary-based particle halo was never done before. We produce theoretical stellar streams under different gravitational potentials, comparing the effects they generate on the ejected stars. The tidal streams production is carried out through a ‘spray’ method and the definition of a tidal radius model. Despite some details we discuss, the resulting fit is good enough to ensure the overall framework can reproduce the observations.
Silvio Ribamar Rodriguez Moncada
Instituto de Astronomía Teórica y ExperimentalMonday 10:15 – 10:40
The formation of bulgeless galaxies
In a hierarchical formation scenario, where structures grow mainly via mergers, the existence of galaxies with a negligible bulge component (bulgeless) can be difficult to explain. In order to investigate the existence of those galaxies we select a sample of galaxies with a negligible spheroidal component from Illustris TNG100 simulation. We notice some differences in the age of the stellar content, sSFR and merger ratio between bulgeless and average spiral galaxies. However, apparently the most important factor that differentiates the formation of bulgeless is the alignment of the gas reservoir and how long stars have formed from this aligned gas. We notice that the bulgeless galaxies have been forming stars aligned with the disc for longer times than for other galaxies. We also notice that the velocity dispersion perpendicular to the disc is lower for bulgeless galaxies than to their counterpart, and has been low for a longer period of time. We also measure the shape of the gas around the galaxies at the redshift at which the stars start to form aligned with the disc, and find that the mayor axis of gas tend to be closer to be perpendicular to the angular momentum of the stars for bulgeless galaxies than for normal spirals.
Coffee Break
Monday 10:40 – 11:20Cecilia Fariña
Isaac Newton Group of TelescopesMonday 11:20 -12:10
WEAVE at the WHT: The journey from input files to final science data and the challenge of optimizing the use of observing time.
WEAVE, the WHT Enhanced Area Velocity Explorer, is a next-generation wide-field spectrograph facility designed for the 4.2-m William Herschel Telescope on La Palma. This highly versatile instrument features a spectrograph with two resolution modes, R ~ 5000 and R ~ 20000, fed by fibers from the 1000-multiplex MOS mode, or from the 20 individual mini-IFUs, with both modes deployable over a 2-degree field of view, or from the large IFU. WEAVE was designed to serve a wide range of scientific goals in fields from stellar and Galactic astronomy to cosmology. The instrument is currently being commissioned at the WHT, and operations will begin in the coming months. In the era of WEAVE, the WHT will be devoted to carrying out observations for the eight core surveys for about 70% of the time, while the remaining 30% of the time will be used for open-time programmes. All observations will be carried out in queue-scheduled service mode. In this talk, we discuss the challenge of optimizing the observing time for WEAVE, given its versatility and design characteristic. We start by introducing the instrument and the planned surveys to provide context. We then focus on the strategies that have been designed to make optimal use of the observing time. Finally, we follow the data on their journey from initial input files to final output science data, highlighting the most interesting features of the instrument, and of the observatory control system designed for WEAVE operations.
Dante Paz
Instituto de Astronomía Teórica y Experimental – Observatorio Astronómico de CórdobaMonday 12:10 – 12:35
A cosmological test using the abundance of Popcorn voids
We present a new definition of cosmic void and a publicly available code with the algorithm that implements it. In this void finder, underdense regions are defined as free-form objects, called popcorn voids, made from the union of spheres of maximum volume with a given joint integrated underdensity contrast. This provides, for the first time, a definition of a void in the matter field whose abundance can be faithfully reproduced by excursion set theory, in particular using the Vdn model without any adjustment or cleaning process. We also analysed the abundance of voids in biased tracer samples in redshift space. We show how the void abundance can be used to measure the geometric distortions due to the assumed fiducial cosmology, in a proof similar to an Alcock-Paczyński test. Using the formalism derived from previous works, we show how to correct the abundance of popcorn voids for redshift-space distortions. Using this treatment, in combination with the excursion set theory, we demonstrate the feasibility of void abundance measurements as cosmological probes. We obtain unbiased estimates of the target parameters, albeit with large degeneracies in the parameter space. Therefore, we conclude that the proposed test in combination with other cosmological probes has potential to improve current cosmological parameter constraints.
Diego Pallero
Pontificia Universidad Católica de ChileMonday 12:35 – 13:00
The survival conditions for massive disks
Nature vs nurture has been a hot topic in modern astronomy since the discovery of the relation between galaxy morphology and the environment in which they reside. In this talk, using hydrodynamical simulations, we try to address this issue. Motivated by recent observational results, we explore the conditions needed for the formation and survailavility conditions of massive disk galaxies (Mstar > 10^11 Msun), using the public catalogues from the state-of-the-art, Illustris-TNG simulation. Contrary to what we expected, these kinds of objects could be found in any environment, from isolation to massive galaxy clusters. Additionally, the number of mergers experienced and the AGN activity of massive disks are not different from what elliptical galaxies experience. Nevertheless, we found that massive disks usually suffer at least one wet merger at z<1, while elliptical galaxies do not experience any wet mergers after this time.
Lunch
Monday 13:00 – 14:30Gian Luigi Granato
Astronomical Observatory of Trieste, ItalyMonday 14:30 -15:20
On the importance of dust in astrophysics, focussing on galaxy formation models
I will spend most of my talk time summarizing what we know about cosmic dust: its properties, its physical effects on the interstellar medium, and how it is formed and evolves. Then I will briefly discuss some results of galaxy formation models, including computations of dust evolution.
Juan Pablo Caso
Instituto de Astrofísica de La Plata (IALP) and Facultad de Ciencias Astronómicas y Geofísicas (FCAG – UNLP)Monday 15:20 – 15:45
Scaling relations for globular cluster systems
The globular clusters (GCs) are compact stellar systems, considered as the massive end in the mass function of stellar clusters. Most of them are old (8-10 Gyr), form at the epoch at which the cosmic star-formation density peaked its maximum. Although several questions remain unresolved about their origin, it is believed that the merger episodes experience by their host galaxy were relevant for their survival and migration to the halo. Subsequent accretion processes that increased the total mass of the galaxy, also enriched the GC system (GCS), shaping its current properties. Hence, the GCSs in the nearby Universe underline the evolutionary history experienced by their host galaxy. The analysis of scaling relations for GCSs is crucial for understanding the relevance of different physical processes involved in their origin and evolution. In recent years, we have carried on a compilation of GCSs properties in early-type galaxies. Based on both, literature results and profiles derived by us, we have built up a sample of 100 GCSs, and analysed the scaling relations as a function of several galaxy parameters (see Caso+ 2019, MNRAS, 488, 4504; De Bórtoli+ 2022, MNRAS, 510, 5725). In this contribution, a sample of nearby massive galaxies are considered, focusing on the inner GCS radial profile. Including the profiles derived in our previous papers, the total sample has ≈60 GCSs with radial profiles homogeneously calculated, and spanning two orders of magnitude in stellar mass of the host galaxy. The results provide evidence to constrain the theories on GCs erosion.
Federico Stasyszyn
Instituto de Astronomía Teórica y Experimental – Observatorio Astronómico de CórdobaMonday 15:45 -16:10
Are there dynamos in cosmological large-scale structures?
Current theories about the evolution of magnetic fields in the Universe suggest that the seed magnetic fields were generated during early stages, and then were amplified and sustained by astrophysical processes such as galactic outflows and other dynamo effects. When analysing cosmological large-scale structures, the magnitude and morphology of large-scale magnetic fields in them is still not clear. I will present some results connecting large-scale structure properties and dynamo models, with the goal to put constraints on the possible growth by the hierarchical structures (cosmic filaments in particular) and internal astrophysical processes. To do so, we analyze cosmological simulations, identifying structures and their mean-flow properties, to be able to re-simulate them to confirm or develop analytical models that can be used to make predictions to observations.
Coffee Break
Monday 16:10 – 16:50Antonela Monachesi
Universidad de La SerenaTuesday 09:00 – 09:50
Patricio Colazo
Instituto de Astronomía Teórica y ExperimentaTuesday 09:50 – 10:15
A new perspective: investigating the detectability of primordial black holes as a dark matter solution
There are numerous candidates for dark matter (DM), with primordial black holes (PBH) being the most massive ones. This study addresses this topic from a numerical point of view to explore theoretical predictions and their potential effects on observables. To do so, we use numerical simulations based on a modified primordial matter power spectrum with two modifications: one to take into account the effect of primordial black holes, in particular, their discreteness which introduces additional Poisson fluctuations. Second: the primordial spectrum includes a modification at unobservable scales smaller than k=10 h Mpc^-1, such that it allows the formation of PBHs in the early universe. This latter change is based on alternative inflation models without which no PBHs would form. The necessary conditions for generating initial conditions from pseudo-linear methods are established, introducing checks of linearity in the amplitude of fluctuations in the initial power spectrum.
Federico Dávila Kurbán
Instituto de Astronomía Teórica y ExperimentalTuesday 10:15 – 10:40
Is clustering in voids special?
We measure the reduced void probability function (VPF) inside and outside of cosmic voids in the TNG300-1 simulation. Numerous redshift surveys have shown agreement with the paradigm of hierarchical scaling of the galaxy clustering moments, particularly with the “binomial model” of hierarchical clustering. It is also known that this scaling breaks down in real space, which has discouraged the use of the VPF as a mainstream tool for studying the high-order clustering of galaxies. In this presentation I show the preliminary result that, despite hierarchical scaling in real space not being preserved throughout the simulation, it can indeed be found inside cosmic voids. This finding indicates that there is hierarchical scaling for the high-order clustering of galaxies inside voids, well fitted by the binomial model, preserving the pristine structure formation processes of the Universe.
Coffee Break
Tuesday 10:40 – 11:20Jiri Horak
Astronomical Institute, Academy of Sciences of the Czech RepublicTuesday 11:20 -12:10
Black-hole accretion disk oscillations and high-frequency variability
Accreting black holes and neutron stars show remarkable variability in their X-ray light curves. In this talk, I will concentrate on the high-frequency variability and its possible theoretical explanations. Most of the attention will be devoted to simple models based on the orbital motion and oscillations of geometrically thin accretion disks. After brief presentation of disk linear modes, we I will discuss their excitation process by nonlinear interactions and resonances.
Ernesto Zurbriggen
Instituto de Astronomía Teórica y ExperimentalTuesday 12:10 – 12:35
An MHD Study of Large-Amplitude Oscillations in Solar Filaments
Quiescent filaments may be affected by internal and/or external perturbations triggering oscillations of different kinds. In particular, external large-scale coronal waves can perturb remote quiescent filaments leading to large-amplitude oscillations. Observational reports have indicated that the activation time of oscillations coincides with the passage of a large-scale coronal wavefront through the filament, although the disturbing wave is not always easily detected. Aiming to contribute to understanding how –and to what extent– coronal waves are able to excite filament oscillations, in this poster we will present 2.5D MHD simulations of a filament floating in a gravitationally stratified corona disturbed by a coronal shock wave. The interaction results in a two-coupled-oscillation pattern of the filament, which is damped in a few cycles. A parametric study was carried out varying parameters of the scenario such as height, size, and mass of the filament. Also, an oscillatory analysis reveals a general tendency for periods of oscillations, amplitudes, and damping times to increase with height, whereas larger filaments exhibit shorter periods and smaller amplitudes. An interesting results of the calculation of forces exerted on the filament shows that the main restoring force is the magnetic tension
Abril Sahade
Instituto de Astronomía Teórica y ExperimentalTuesday 12:35 – 13:00
Understanding the deflection of the ‘Cartwheel CME’
We study the low corona evolution of the `Cartwheel’ coronal mass ejection (CME; 2008-04-09) by reconstructing its 3D path and modeling it with magneto-hydrodynamic simulations. This event exhibits a double-deflection that has been reported and analyzed in previous works but whose underlying cause remained unclear. The `Cartwheel CME’ travels toward a coronal hole (CH) and against the magnetic gradients. Using a high-cadence, full trajectory reconstruction, we accurately determine the location of the magnetic flux rope (MFR) and, consequently, the magnetic environment in which it is immersed. We find a pseudostreamer (PS) structure whose null point may be responsible for the complex evolution of the MFR at the initial phase. From the pre-eruptive magnetic field reconstruction, we estimate the dynamic forces acting on the MFR and provide a new physical insight on the motion exhibited by the 2008-04-09 event. By setting up a similar magnetic configuration in a 2.5D numerical simulation we are able to reproduce the observed behavior, confirming the importance of the PS null point. We find that the magnetic forces directed toward the null point cause the first deflection, directing the MFR towards the CH. Later, the magnetic pressure gradient of the CH produces the reversal motion of the MFR.
Lunch
Tuesday 13:00 – 14:30Yael Judith Aidelman
Instituto de Astrofísica de La Plata (CONICET – UNLP)Tuesday 14:30 – 15:20
Reddening-Free Q Parameters to Classify B-Type Stars with Emission Lines
The emission-line B-type stars constitute a heterogeneous group. Many of these stars show similar optical spectroscopic features and color indices, making it difficult to classify them adequately by means of photometric and spectroscopic techniques. Thus, it is relevant to deal with appropriate classification criteria to avoid as many selection effects as possible. For this purpose, we analyzed different reddening-free Q parameters, taking advantage of the Gaia and 2MASS photometric surveys, for both main sequence and emission-line B-type stars. Along with this work, we provided various criteria to search for normal and emission-line B-type stars, using different color–color, Q–color, and Q–Q diagrams. It was also possible to identify stars in different transition phases (i.e., (Rp − J) vs. ( J − Ks) diagrams) and to classify them according to their NIR radiation excesses (i.e., the ( Bp − Rp ) vs. ( H − Ks ) diagram). Other diagrams, such as the Q_JKHK vs. ( H − Ks) or Q_BpJHK vs. ( Bp − Ks), were very useful to search for and classify different classes of B-type stars with emission lines. The amount of intrinsic dust emission in the diverse groups of emission-line stars was well-recognized via the Q_JHK vs. Q_BpRpHK diagram. The different selection criteria are very important tools for automated designs of machine learning and optimal search algorithms.
Susana Beatriz Araujo Furlan
Instituto Argentino de Radioastronomía – CONICET, Observatorio Astronómico de Córdoba – UNC, FAMAF – UNCTuesday 15:20 -15:45
Preliminary results of the study of radio emission from southern magnetars with the radiotelescopes of the Argentine Institute of Radioastronomy
We present the preliminary results of the study of radio emission from magnetars with the radio telescopes Carlos Varsavsky and Esteban Bajaja of the Argentine Institute of Radio Astronomy (IAR). Magnetars are a particular class of young, slowly rotating neutron stars with extremely high surface magnetic fields ( B ~ 1013 – 1015 G). They exhibit X-ray and γ-ray outbursts, whose energy is provided by the decaying magnetic fields. A handful of magnetars have associated pulsed radio emission and a few also have exhibited large, isolated, and fast radio flares. Studying magnetars and their pulsed emission in radio is necessary for enlightening the characteristics of their remarkable spectral and temporal phenomenology. Additionally, magnetars have long been suspected to be the source of another transient radio phenomenon, fast radio bursts (FRB). Recently, the detection of a FRB associated with the galactic magnetar SGR 1935+2154 lends strong support to the idea that starquakes in magnetars trigger at least some of these events. Pulsating radio emission from magnetars has been detected throughout a long range of frequencies (~ 1 – 45 GHz) with single dish telescopes. Here we present the first analysis made for observations of magnetar J1810-197 over the course of the second half of 2022.
Catalina Casanueva Villarreal
Pontificia Universidad Católica de ChileTuesday 15:45 -16:10
Primordial black holes as candidates for dark matter and posible feedback source at very high redshift
We aim to study the formation of the first galaxies and the regulation of star formation at early times through analysis of the role of primordial black holes (PBHs) as sources of energy injection and their relative relevance to the other feedback mechanisms present at high redshift (POP III, SN and HMXBs). Specifically, we seek to: (i) incorporate these feedback mechanisms into numerical simulations to analyze their joint evolution, (ii) develop and test a model for early feedback by PBHs, (iv) evaluate the relative contribution of the different feedback mechanisms as a function of time, and (v) derive predictions and envisage observational evidence that can help us constrain theoretical models. In particular, studying the impact of feedback by PBHs, we aspired to set constraints to the fraction of dark matter that could exist as PBHs as a function of their masses.
Coffee Break
Tuesday 16:10 – 16:50Claudia Graciela Scóccola
FCAG-UNLP / CONICETTuesday 16:50 -17:40
The Q & U Bolometric Interferometer for Cosmology: Status and Prospects
The Q & U Bolometric Interferometer for Cosmology (QUBIC) is a cutting-edge CMB polarimeter installed on the Puna plateau in Argentina. Its optimized design enables the measurement of B-mode polarization, one of the major challenges of observational cosmology. However, this signal is subject to systematic effects and astrophysical foregrounds, which QUBIC aims to control through multichroic observations and a novel approach called Bolometric Interferometry. This technique combines the advantages of interferometry and bolometric detectors to produce wide-band, background-limited sensitivity. Additionally, the QUBIC synthesized beam’s frequency-dependent shape produces maps of the CMB polarization in multiple sub-bands within the instrument’s two physical bands. QUBIC is thus complementary to other instruments and particularly suited to characterizing and removing Galactic foreground contamination. In this talk, I will present the status of QUBIC, including calibration results, the first real sky observations, and forecasts for B-modes detection. I will also highlight QUBIC’s unique spectral-imaging feature, which allows it to identify foreground contamination, even in the pessimistic case of Galactic dust exhibiting frequency domain decorrelation.
Poster Session 1
Tuesday 17:40 – 18:30Nicolás Garavito-Camargo
Flatiron Institute, United StatesWednesday 09:00 – 09:50
Doris Stoppacher
Wednesday 09:50 – 10:15
Hidden-Figures: Exploring the low-surface brightness universe
Low-surface-brightness galaxies (LSBGs) are defined as galaxies with a central surface brightness fainter than the night sky. They consist of an exceptional population of galaxies challenging to observe and difficult to characterize since they do not show any clear patterns but populate a wide range of properties such as sizes and morphologies. Furthermore, works realized with numerical techniques featuring this LSBGs are highly under-represented in the literature compared to other fields of research We find it of extraordinary importance and necessity to account for these shortcomings, considering that LSBGs dominate the volume density of galaxies. Therefore we present a new research project on the topic an present our first results on the study of LSBGs, their environment, and assembly histories from hydro-dynamical simulations.
Octavio Guilera
Instituto de Astrofísica de La PlataWednesday 10:15 – 10:40
Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets
Most of the works dealing with planet migration focus on the interaction between the planet and the gaseous disk, neglecting the role of the dust. However, multifluid hydrodynamical simulations performed in the last quinquennium have shown that the dust can generate a non-negligible contribution to the total torque over the planet. We recently incorporated the results of this phenomenon from hydro simulations in our global model of planet formation. We will show that the dust torque can generate significant regions of outward planet migration for a wide range of disk parameters and Stokes numbers. Thus, the aim of this talk is to show the impact of the torque exerted by the solid component of the disk on the migration of low-mass planets growing by pebble accretion.
Coffee Break
Wednesday 10:40 – 11:20Andrea Fortier
University of BernWednesday 11:20 -12:10
The CHEOPS Mission
In 1995, Swiss astronomers discovered the first exoplanet orbiting a solar-like star, earning them the Nobel Prize in Physics in 2019. Since then, over 5000 exoplanets have been discovered through ground and space surveys, prompting the need for further characterization. The CHaracterising ExOPlanet Satellite (CHEOPS) was designed for this purpose as a follow-up mission to study planets with high scientific value. Launched in 2019, CHEOPS is the first ESA Small Mission and observes transiting exoplanets with ultrahigh precision photometry on bright stars (V<13). CHEOPS' photometry also allows obtaining phase curves of hot giant planets and even searching for exo-moons. Furthermore, by identifying transiting exoplanets with high potential for in-depth characterization, CHEOPS will provide prime targets for future instruments to study exoplanetary atmospheres (e.g. JWST, PLATO, ARIEL, etc.). This talk will cover CHEOPS' primary objectives, construction challenges, operation, and significant scientific results, including the first approved extension to ensure operation until the end of 2026.
Daniel David Sega Neuman
University of Colorado, Boulder/br> Wednesday 12:10 – 12:35The enhancement of angular momentum transport due to self-gravity wakes and its implication in the formation of gaps in disks.
The satellite Mimas launches a bending wave —a warping of the rings that propagates radially through self-gravity— at the 5:3 inner vertical resonance with Saturn’s rings. We present a modification of the linear bending wave theory (Shu, et al, ICARUS 53, 1983) which includes the effects of satellite self-gravity wakes on the particles in the wave. We show that these satellite wakes generate an extra layer of particles whose number density is proportional to the magnitude of the ring’s slope. Our best model explains the most discrepant and surprising features of the Mimas 5:3 bending wave; the bigger than expected viscosity, which is more than double the viscosity computed from density waves in the nearby region of the A-ring. This shows that self-gravity wakes are especially effective in preventing the opening of gaps in a vertically perturbed disk and that the generation of warps can be an effective dissipative process. The enhanced angular momentum transport (viscosity) due to vertical resonances may be an important when considering Mimas orbital evolution.
Federico Zoppetti
Instituto de Astronomía Teórica y Experimental – Observatorio Astronómico de CórdobaWednesday 12:35 – 13:00
Tidal orbital evolution of circumbinary planets
Most confirmed circumbinary planets are located very close to their host binary where the tidal forces are expected to play an important role in their dynamics. Here we consider the orbital evolution of a circumbinary planet with arbitrary viscosity, subjected to tides due to both central stars. We adopt the creep tide theory and assume that the planet is the only extended body in the system and that its orbital evolution occurs after acquiring its pseudo-synchronous stationary rotational state. With this aim, we first performed a set of numerical integrations of the tidal equations, using a Kepler-38-type system as a working example. For this case we find that the amount of planetary tidal migration and also, curiously, its direction both depend on the viscosity. However, the effect of tides on its eccentricity and pericenter evolutions is simply a move toward pure gravitational secular solutions. Then we present a secular analytical model for the planetary semimajor axis and eccentricity evolution that reproduces very well the mean behavior of the full tidal equations and provides a simple criterion to determine the migration directions of the circumbinary planets. This criterion predicts that some of the confirmed circumbinary planets are tidally migrating inward, but others are migrating outward. However, the typical timescales are predicted to be very long, and not much orbital tidal evolution is expected to have taken place in these systems. Finally, we revisit the orbital evolution of a circumbinary planet in the framework of the constant time lag model. We find that the results predicted with this formalism are identical to those obtained with creep theory in the limit of gaseous bodies.
Facundo A. Gómez
Universidad de La Serena, ChileThursday 09:25 – 10:15
Germán Alfaro
Instituto de Astronomía Teórica y ExperimentalThursday 10:15 – 10:40
How galaxies populate halos in extreme density environments? An analysis of the halo occupation distribution in SDSS
Recent works have shown that the properties of galaxy populations in simulated dark matter halos vary with large-scale environments. These results suggest a variation in the Halo Occupation Distribution (HOD) in extreme-density environments since the dynamic and astrophysical conditions prevailing in these regions may significantly affect the formation and evolution of their halos and residing galaxies, influencing the mean number of satellite galaxies. Our goal is to use the Sloan Digital Sky Server Data Release 12 (SDSS-DR12) to build a volume complete galaxy sample, identify Cosmic Voids and Future Virialized Structures (FVSs) and characterize the HOD within these structures. We use a publicly available galaxy group catalogue as a proxy for dark matter halos. We also studied the dependence of the results on the main Void and FVS properties. In all cases, we compared the results with those derived from the field sample, defined by objects outside of both types of environments. As the main results, inside Voids, we find a strong decrease in the HOD concerning the field results. In the most extreme cases (groups with masses above ∼10e13h−1Msun) the mean number of satellites falls to ∼50%. Inside FVSs, the HOD shows a significant increase to the field, with a ∼40% excess in the mean number of satellites for groups with masses around 10e14h−1Msun. These results are present for the different galaxy luminosity ranges explored. In both environments, the differences with respect to the field increase for the extreme values of the density environments.
Coffee Break
Thursday 10:40 – 11:20Miriam Peña
Instituto de Astronomía, Universidad Nacional Autónoma de MéxicoThursday 11:20 -12:10
The Chemical Abundances in Planetary Nebulae
I will present the procedures used to determine physical conditions and chemical abundances in Planetary Nebulae, from collisionally excited lines (CELs) and recombination lines (ORLs). The differences between these results, in the form of the Abundance Discrepancy Factors (ADF) will be discussed and the possible causes will be exposed. The evidence for the existence of different plasmas with different distributions and different chemistry will be mentioned.
Marcelo Miguel Miller Bertolami
Instituto de Astrofísica de La PlataThursday 12:10 – 12:35
¿Por qué, y por qué no, las estrellas se vuelven gigantes rojas ?
We present a possible explanation for the question “why do stars become red giants?”, emphasizing the structural reasons why this occurs both in low-mass and high-mass stars. We present an analytical model to understand the structure of stars in which nuclear reactions occur off-center (in a spherical shell). We analyze the consequences of this model and apply it to understand the properties observed in the numerical models in the giant branch, with special emphasis on the so-called “Red Giant Branch Bump”. This presentation is based on recently published work in Miller Bertolami (2022, 2023, ApJ).
María Paula Ronco
Instituto de Astrofísica de La Plata/br> Thursday 12:35 – 13:00Protoplanetary disk evolution around intermediate mass stars
Authors: Ronco, M. P., Villaver, E., Schreiber, M., Guilera, O.M., Miller Bertolami, M.M. Most studies of the evolution of protoplanetary disks and planet formation focus on low-mass stars (M<1Msun) since the majority of the confirmed exoplanets have been found around these kinds of stars. However, despite the difficulties of detecting planets around intermediate mass stars (~1-3Msun), a non-negligible occurrence rate of giant planets has been proved via radial velocity campaigns around this mass range. In addition planets have been detected through direct imaging around young A-stars. On the other hand, planet formation around intermediate mass stars is related to the most frequent stellar remnants: white dwarfs. Only a few planet candidates have been detected around white dwarfs so far, but about one third of white dwarfs show metal absorption lines which are thought to be caused by the accretion of planetary remnants. As a first step towards a better understanding of planet formation around intermediate mass stars, we here explore the gas protoplanetary disk evolution around intermediate-mass stars affected by the effects of stellar evolution, which are important during these disks dissipation timescales. We compute the time evolution of gas disks around intermediate mass stars (1-3Msun) affected by X-ray and FUV photoevaporation from the central star, varying the viscosity parameter and the initial mass of the disk. We find new and fundamentally different evolutionary pathways for the gas evolution that will likely have a significant impact on the evolution of the solid component and on planet formation scenarios.
Lunch
Thursday 13:00 – 14:30Verónica Firpo
Gemini Observatory- NOIRLabThursday 14:30 – 15:20
El Observatorio Gemini desde el lado de las operaciones científicas
En esta charla contaré cómo es trabajar en un observatorio de servicio, describiendo algunas de las tareas del staff del grupo de ciencia, como ser: observaciones en modo cola, soporte de los investigadores externos en la preparación de sus observaciones, soporte en la instrumentación de Gemini, planificación de los “planes de observación”, trabajos asociados a proyectos en desarrollo del Observatorio, chequeo de instrumentos, evaluación de la calidad de los datos científicos, entre otros.
Celeste Parisi
Instituto de Astronomía Teórica y Experimental – Observatorio Astronómico de CórdobaThursday 15:20 – 15:45
The spectroscopic follow up of the VISCACHA Survey and the Calcium Triplet Technique
The GMOS-Gemini trinational spectroscopic follow up of the VISCACHA Survey, between Chile, Brazil and Argentina, has taken advantages of the efficiency of the Calcium Triplet Technique for the accurate SMC cluster metallicity determinations. In this talk I will show the current state of the observations and analysis. On the other hand, I will summarize the main results that we have obtained so far related to the chemical evolution of the SMC.
Ingrid Vanessa Daza Perilla
Instituto de Astronomía Teórica y ExperimentalThursday 15:45 -16:10
The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc
The automated identification of extragalactic objects in large photometric surveys provides reliable and reproducible samples of galaxies in less time than procedures involving human interaction. This problem, however, is more challenging in regions near the Galactic disc where the extinction by dust is greater. We present the methodology for the automatic classification of galaxies and non-galaxies at low Galactic latitude regions using both images and, photometric and morphological near-IR data from the VVVX survey. Using the VVV NIRGC, we analyse by classical and unsupervised statistical methods the most relevant features for galaxy identification. This catalogue was also used to generate datasets of extragalatic candidates from a pipeline and train a Convolutional Neural Network with image data and an Extreme Gradient Boosting architecture with photometric and morphological data. This allows us to derive probability catalogues used to analyse the completeness and purity as a function of the configuration parameters and to explore the best combinations of the models. The resulting classifier reaches an F1-score of 0.67, a purity of 65 per cent and a completeness of 69 per cent. As a test case, we apply this methodology to the VVVX survey in part of the Northern disc region, generating a dataset of 172,396 extragalatic candidates with probabilities of being galaxies. In addition, we present the VVV NIR Galaxy Catalogue.
Coffee Break
Thursday 16:10 – 16:50Anahi Granada
LICA, Universidad Nacional de Rio Negro.Thursday 16:50 -17:40
Detecting and Characterizing Active Be stars in open clusters
Even though Be stars constitute about 30% of early B-type stars, or even more in some young open clusters, neither the origin of the rapid rotation of these stars is still well understood, nor how close to criticality they rotate, or what the mechanisms involved in the development of their circumstellar discs are. In order to contribute to a better understanding of the physical conditions under which Be stars form and evolve, it is imperative to further investigate the content of Be stars in young or intermediate-age open clusters, in particular those whose stellar populations have not been studied in detail. In this talk, I will describe a new method to detect and characterize active Be stars combining photometric data from Gaia DR2 and DR3 (Granada et al. 2023). We have tested our methodology in four open clusters widely studied in the literature known to host numerous Be stars and are now applying this methodology to other open clusters to increase the number of Be candidates.
Poster Session 1
Thursday 17:40 – 18:30Anabella Araudo
Extreme Light Infrastructure ERIC, ELI Beamlines FacilityFriday 09:00 – 09:50
Acceleration of ultra high energy cosmic rays in AGN jets and outflows
The origin of the Ultra High Energy Cosmic Rays (UHECRs) is still unclear. The arrival direction of UHECRs is coincident with starburst galaxies and Active Galactic Nuclei (AGN), but the former do not have enough power to accelerate particles up to energies ultra-high energies. Backflows in the jet termination region in powerful radiogalaxies offer a suitable environment for accelerating particles up to the Hillas limit that, for the plasma conditions in the backflows is about the energy of UHECRs. In particular, Centaurus A in its most powerful phase 20 Myr ago should have had huge backflows to accelerate the UHECRs that we see nowadays reflected in M82 and other giant galaxies. Although this possibility looks very plausible, it is still necessary to have heavy elements in the backflows in order to explain the rich composition of the UHECR spectrum. Centaurus A is the result of a collision of two normal galaxies resulting in a fantastic jumble of star clusters. When young stars (and clusters) encounter a jet, the jet ram pressure confines the stellar wind producing a double shock structure where instabilities mix up the wind (rich in heavy elements) and the jet plasma in the turbulent tail downstream of the star. Our studies show that jet/star interactions are an efficient mechanism to load the jets with heavy ions that will then be accelerated up to ultra high energies in the huge backflows in the jet termination region. This result has important implications for the origin of UHECRs.
Benedict Rouse
Pontificia Universidad Católica de ChileFriday 09:50 – 10:15
Investigating the effect of environment on AGN activity in EAGLE
We explore the properties of AGN and their host galaxies in the EAGLE simulation, as a function of their distance to the centre of the closest void. We split the environments into four groups: Inner void, Outer Void, Wall galaxies and Skeleton galaxies. We find that the percentage of galaxies hosting an AGN decreases with increasing distance from the centre of the void. This is particularly clear in galaxies with Mstellar >10^10. We study various AGN host-galaxy parameters from the EAGLE simulations and discover that on average, across all regions there is very little difference in the current values of SFR, sSFR, BH mass, stellar masses and the time for the galaxy to form half of its mass. Therefore, we assume that the differing AGN activity across varying environments isn’t dependent on the host galaxy properties. We do find that the fraction of AGN that have experienced a recent merger varies significantly between environments. AGN in underdense regions are far more likely to have had a recent minor merger, when compared to AGN in dense regions that experience far fewer. Because of this, we hypothesise that the most efficient method for fuelling an AGN is through a minor merger in a galaxy in an underdense environment.
Adriana R. Rodríguez Kamenetzky
famaf-iate-OACFriday 10:15 – 10:40
Resolving the collimation zone of intermediate- and high-mass protostellar jets
It is well known that astrophysical jets play a crucial role in the evolution of the systems hosting them. However, a fundamental understanding of how they work has not been achieved, i.e., how they are launched and collimated. In this regard, protostellar jets constitute excellent touchstones to shed light on this topic, mainly due to their proximity, which allows us to probe close to their launching platforms. In the past decades, radio interferometric observations, mainly performed with the VLA at 6cm and 3cm bands, have allowed to impose an upper limit of 100 au to the distance from the protostar at which the collimation takes place. This limit does not allow yet to decide for a specific mechanism; thus, a better understanding of the jet phenomenon and its impact in how protostars grow, requires to resolve this collimation region. Here we present high angular resolution observations of two protostellar jets at ~7 mm, resolving their innermost 100 au for the first time: the massive young stellar object Cep A HW2, and the triple source in Serpens, powered by an intermediate-mass protostar. We also highlight the importance of future LLAMA+ALMA observations in Band 1 regarding this subject.
Coffee Break
Friday 10:40 – 11:20Daniel Horta
Flatiron InstituteFriday 11:20 -12:10
Characterizing halo substructure in the Milky Way with APOGEE and Gaia
Galactic haloes in a Λ-Cold Dark Matter (ΛCDM) universe are predicted to host today a swarm of debris resulting from cannibalised dwarf galaxies that have been accreted via the process of hierarchical mass assembly. The chemo-dynamical information recorded in the Galactic stellar populations associated with such systems helps elucidate their nature, placing constraints on the mass assembly history of the Milky Way. Using data from the APOGEE and Gaia surveys, I will present an examination of APOGEE targets belonging to the following substructures in the stellar halo: Heracles, Gaia-Enceladus/Sausage (GES), Sagittarius dSph, the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1, Arjuna, I’itoi, Nyx, Icarus, and Pontus. By examining the distributions of all substructures in chemical space considering the abundances of elements sampling various nucleosynthetic pathways, in this talk I will show results that help elucidate the reality and nature of halo substructures in the Milky Way. The results from this work help place constraints on the accretion history and mass assembly history of the Galaxy.
Antonio David Montero Dorta
Universidad Tecnica Federico Santa Maria (USM)Friday 12:10 – 12:35
Secondary halo bias: physical origins, observability and mock generation
Universidad Tecnica Federico Santa Maria (USM) 1 A44 Chile Galaxies and Cosmology Yes, oral oral B22 Secondary halo bias: physical origins, observability and mock generation Virtually all internal halo properties display a certain level of secondary halo bias, i.e., the dependence of halo bias on a secondary property at fixed halo mass. A noteworthy example of these dependencies is the so-called halo assembly bias effect, the dependence on the assembly history of halos. These established trends are also expected to manifest themselves on galaxy clustering through a potential set of effects known as galaxy assembly bias. In my talk, I would like to discuss both the physical origins and the observability of the trends, along with their implications for galaxy formation and observational cosmology. I will also show how machine learning algorithms can capture the galaxy assembly bias signal from hydrodynamical simulations with outstanding precision, which has significant advantages for galaxy mock generation.
Nelson David Padilla
Instituto de Astronomía Teórica y Experimental – Observatorio Astronómico de CórdobaFriday 12:35 – 13:00
Interactions between charged dark matter and baryons in galaxies
We will present recent results on the interactions between baryons and different candidates for dark matter that hold electric charge. These interactions take the form of Coulomb scattering events which can heat up ionized gas clouds in galaxies. We will discuss two possible candidates of charged dark matter, (i) mili-charged dark matter particles, with very low charges compared to electrons and protons but with quite high number densities across galaxies, and (ii) primordial black holes as, in a recent paper, we have shown that these should be endowed with a non-zero electric charge. These interactions provide another way to constrain the maximum abundance of charged dark matter in the Universe.