SALÓN AZUL
09:00 - 09:50
Plenary Review Talk
Invited Speaker:
Francisco Förster
- Universidad de Chile
(Chile)
[cv]
Francisco Förster
Universidad de Chile
Curriculum Vitae:
Professor at U. of Chile, Data and Artificial Intelligence Initiative. Associate Researcher at the Millenium Institute of Astrophysics, researcher at the Center for Mathematical Modeling, Fondecyt Regular Fellow. Obtained D.Phil. at the University of Oxford in theoretical studies on supernova progenitors. Principal Investigator of the ALeRCE project, an astronomical alert broker for next generation survey telescopes selected as Community Broker for the Vera C. Rubin Observatory; and of the High cadence Transient Survey (HiTS), a real–time search for very young supernova using the Dark Energy Camera.
Chair: Javier Licandro
#605 |
The ALeRCE astronomical alert broker
Francisco Förster
1
1 - Universidad de Chile.
Resumen:
A new generation of large aperture and large field of view telescopes is allowing the exploration of large volumes of the Universe in an unprecedented fashion. In order to take advantage of these new telescopes, notably the Vera C. Rubin Observatory, a new time domain ecosystem is developing. Among the tools required are fast machine learning aided discovery and classification algorithms, interoperable tools to allow for an effective communication with the community and follow-up telescopes, and new models and tools to extract the most physical knowledge from these observations. In this talk I will review the challenges and progress of building one of these systems: the Automatic Learning for the Rapid Classification of Events (ALeRCE) astronomical alert broker. ALeRCE (http://alerce.science/) is an alert annotation and classification system led by an interdisciplinary and interinstitutional group of scientists from Chile since 2019. ALeRCE is focused around three scientific cases: transients, variable stars and active galactic nuclei. Thanks to its state-of-the-art machine learning models, ALeRCE has become the 3rd group to report most transient candidates to the Transient Name Server, and it is enabling new science with different astrophysical objects, e.g. AGN science. I will discuss some of the challenges associated with the problem of alert classification, including the ingestion of multiple alert streams, annotation, database management, training set building, feature computation and distributed processing, machine learning classification and visualization, or the challenges of working in large interdisciplinary teams. I will also show some results based on the real‐time ingestion and classification using the Zwicky Transient Facility (ZTF) alert stream as input, as well as some of the tools available.
09:50 - 10:20
Plenary Target Talk
Invited Speaker:
Marcio Meléndez
- Space Telescope Science Institute
(EE.UU.)
[cv]
Marcio Meléndez
Space Telescope Science Institute
Curriculum Vitae:
El Dr. Marcio Meléndez obtuvo una Licenciatura en Física en la Universidad Simón Bolívar de Venezuela y después una Maestría en Física en el Instituto Venezolano de Investigaciones Científicas, IVIC. Durante este tiempo su trabajo de investigación se enfocó en realizar cálculos atómicos de plasmas astrofísicos. Posteriormente continuó sus estudios en la Universidad Católica de América, en Washington DC, donde obtuvo una Maestría y Doctorado en Física, realizando en el Centro Goddard de la NASA su trabajo de tesis doctoral sobre agujeros negros super masivos en el centro de galaxias activas. En el 2008 obtuvo una beca de investigación como parte del programa postdoctorante de la NASA (NPP) para trabajar con observaciones de galaxias activas usando el telescopio espacial en el infrarrojo Spitzer. Seguidamente obtuvo posiciones como investigador en el departamento de Física y Astronomía de la Universidad John Hopkins y Departamento de Astronomía de la Universidad de Maryland. En el 2015 se unió al equipo de óptica del módulo integrado de instrumentos científicos del telescopio espacial James Webb donde participó en las pruebas al vacío del telescopio realizadas en los centros de la NASA, Goddard y el centro espacial Johnson en Houston, Texas, EEUU. Actualmente el Dr. Marcio Meléndez es científico principal de óptica astronómica en el Instituto Científico del Telescopio Espacial en Baltimore, Maryland, EEUU. Dr. Meléndez participó en la comisión del elemento óptico del telescopio espacial James Webb, en particular, la alineación de sus espejos hasta lograr imágenes, limitada solamente por la difracción. Los intereses científicos de Dr. Meléndez están relacionados con el estudio de los agujeros negros supermasivos en el centro de galaxias activas y su interacción con la galaxia en la que residen.
Chair: Javier Licandro
#599 |
The James Webb Space Telescope: commissioning and first year of operations
Marcio Meléndez
1
1 - Space Telescope Science Institute.
Resumen:
The James Webb Space Telescope (JWST) is a segmented deployable telescope for infrared astronomy, launched on December 25th, 2021 and currently operating at L2. In this talk, I will summarize the details of Webb’s Optical Telescope Element commissioning process that began about 1 month after launch and finished with the release of its first public images. I will describe the wavefront sensing commissioning process that transformed an array of 18 scattered mirror segments into a phased telescope, producing diffraction-limited images. I will share my experience as a member of the wavefront sensing and control group at the Space Telescope Science Institute (STScI) and show the evolution of Webb imaging; from first light to its first year of science operations. I will conclude with a summary of the telescope current optical stability and a list of lessons learned that can be valuable for the future of large segmented cryogenic space telescopes.
10:20 - 11:00
COFFEE BREAK
11:00 - 12:30
J: Galaxies and Cosmology
Early Universe / AGN
Chair: Félix Mirabel
#230 |
XQR-30: Black hole masses and accretion rates for 42 z \textgreater 6 quasars
Chiara Mazzucchelli
1
1 - Universidad Diego Portales.
Resumen:
Luminous, high-redshift ($z>6$) quasars are formidable probes of the universe
in the Epoch of Reionization. They are observed to already host super-massive
black holes (BHs) in their centers, and to reside in the earliest, most
massive galaxies, where they are thought to be surrounded by large galactic
over-densities. How BHs and hosts get this massive in such short amount
of time after the Big Bang is one of the key open questions of current
astrophysics. Here, we present bolometric luminosities, BH masses and
Eddington ratios for 42 luminous quasars at z>6 using, for the first
time, high signal-to-noise ratio VLT/X-Shooter spectra, acquired as part
of the ESO Large Programme XQR-30. We find that quasars at high-redshift
host slightly less massive BHs which accrete slightly more rapidly
than a bolometric luminosity matched quasars sample at $z\sim 1$,
and we explore the repercussion of such results with respect to
BH seeds formation and evolution scenarios.
#015 |
Search for LAE galaxies at z~6 in the Thesan simulations
Luz Ángela García
1
1 - Universidad ECCI.
Resumen:
In this work, we study the number density of Lyman Alpha Emitter (LAE) galaxies, their physical properties, and synthetic spectra at redshift ~ 6 using high-resolution hydrodynamical simulations with radiative transfer from the Thesan project. By recreating the scenario described in Becker et al. 2018, we test the hypothesis that observations to date are missing the vast majority of the high-redshift galaxies' signal since they are extremely faint and, thus, are out of the observational limits of our current telescopes. We also follow the evolution of the neutral Hydrogen fraction, the chemical enrichment of the circum- and intergalactic medium, and specific star formation rate of galaxies in the simulation at the end of Reionization, and evaluate why the detections from HST and the Silverrush project significantly underestimate the number of faint galaxies. Our study indicates an observational bias to massive galaxies in the field. Thus, we forecast the properties of the dwarf galaxies responsible for completing the budget of ionizing photons that concluded the Epoch of Reionization.
#319 |
First detection of a newborn AGN
Patricia Arevalo
1
;
Elena López Nava
1
;
Mary Loli Martínez Aldama
2
;
Paula Sánchez-Sáez
3
;
Santiago Bernal
1
;
Lorena Hernández García
1
;
Paulina Lira
4
1 - Universidad de Valparaíso.
2 - Universidad de Concepción.
3 - ESO.
4 - Universidad de Chile.
Resumen:
Observations and models indicate that the fraction of active galaxies in the local Universe is about 10\% . As most large galaxies host a supermassive black hole (SMBH), this can be interpreted as a duty cycle, where 10\% of galaxies are active at any given time. Estimating this activation rate is important to constrain central black hole feeding mechanisms in galaxy evolution models. Black hole ignition events, which involve a galaxy transitioning from a quiescent or star-forming state to a an AGN are, however, exceptionally challenging to detect.
For our work, we took advantage of the very large public photometric monitorings that are currently ongoing together with machine-learning algorithms for selecting interesting objects. Black hole ignition event candidates were selected form a parent sample of spectrally classified non-active galaxies ($>2.300.000$ objects), that currently show optical flux variability indicative of a type I AGN, according to the ALeRCE light curve classifier. In this talk we will present spectral results for the most convincing case of new AGN activity, for a galaxy with a previous star-forming optical classification, where the confirmation spectrum shows the appearance of prominent, broad Balmer lines without significant changes in the narrow line flux ratios. MIR colors have also evolved from typical non active galaxy colors to AGN-like colors.
#144 |
The deepest and sharpest radio continuum map of the sky: the VLA 10GHz Survey of GOODS-N
Eric Jimenez Andrade
1
1 - Institute of Radio Astronomy and Astrophysics/UNAM.
Resumen:
Structural analyses of high-redshift galaxies are key to understanding the physical processes that drive galaxy evolution across cosmic time. While high-resolution observations from the HST and JWST open a window into dust-unobscured star formation and stellar mass content of high-redshift galaxies, radio continuum imaging at sub-arcsec resolution is needed to trace dust-obscured star formation that dominates the star formation rate density of the Universe out to $z\approx5$. To address this open issue, we have conducted the first high-resolution (0.2 arcsec), high-frequency observational campaign to fully map an extragalactic deep field at unprecedented sensitivity: ``The VLA 10GHz Survey of GOODS-N’’. Surveying the extragalactic sky at 10GHz has the advantage of yielding higher angular resolution imaging while probing thermal (free-free) radiation of high-redshift galaxies, which is more directly proportional to the rate of massive star formation. The deep 10GHz images of GOODS-N, thereby, provide an extinction-free view for the morphologies of massive star-forming galaxies out to $z\approx3$ on 1.7kpc scales. In this talk, I will review the key science goals of the “VLA 10GHz Survey of GOODS-N”, present the initial results, and describe the plans for the data release. Finally, I will discuss how the ``VLA 10GHz Survey of GOODS-N’’ will serve as a pathfinder for future ngVLA observations to trace the sub-kpc scale distribution of star formation of high-redshift galaxies.
#247 |
On the nature of type 2 quasars
Gabriel Roberto Hauschild-Roier
1
;
Thaisa Storchi-Bergmann
1
1 - Universidade Federal do Rio Grande do Sul.
Resumen:
Quasars and QSOs are the most luminous objects in the Universe, having bolometric luminosities Lbol > 10$^{46}$ erg/s produced by a Supermassive Black Hole (SMBH) with a high accretion rate in the nucleus of their host galaxies. The SMBH is surrounded by an accretion disk and emitting clouds with velocities in excess of 1000 km/s, surrounded by a dusty molecular torus at ~pc scales. In the Unified Model of AGN (Active Galactic Nuclei), this torus blocks the view of the inner region if observed "edge-on", in the so-called type 2 QSOs. Type 1 QSOs, on the other hand, are supposed to be seen face-on and do not show obscuration. However, there has been some evidence suggesting that these two types of objects do not differ only due to orientation. The goal of this work is to investigate this for a QSO sample, comparing the optical spectral properties of QSO 1 with those of QSOs 2 using, in particular, the [O III] emission-line doublet for the quasar sample from SDSS DR 16, named DR16Q, to investigate a QSO 1 and 2 subsample within 0.4 < z < z 0.5. We found that the [O III] kinematic profile, traced by the W80 parameter, shows that the QSO 2 population has a broader profile than those for the QSOs 1. Moreover, the [O III] luminosity is higher for the QSOs 2 than for the QSOs 1. Both results suggest that there is a difference between these two QSO populations that cannot be fully explained by the AGN Unified Model. Our next step is to check if this difference persists up to z = 1 (when the [O III] doublet goes out of the SDSS wavelength range).
12:30 - 14:30
LUNCH
14:30 - 15:20
Plenary Review Talk
Invited Speaker:
Luis A. Núñez
- Universidad Industrial de Santander
(Colombia)
[cv]
Luis A. Núñez
Universidad Industrial de Santander
Curriculum Vitae:
Experimental particle physics and Astrophysics are global endeavours out of necessity. The sheer scale of designing, constructing, and operating immense equipment, along with managing and analysing vast data sets, often demands the collaboration of hundreds or even thousands of individuals, alongside funding from numerous nations. Participation in these endeavours offers individuals, institutions, and countries access to valuable training, cutting-edge technology, and a wealth of knowledge. However, becoming fully integrated into international experimental research efforts is a process that often spans generations.
During this presentation, we will provide an overview of various initiatives underway in Latin America. One is the BELLA initiative, establishing a state-of-the-art transcontinental fibre optic connecting research and education networks of Europe (GÉANT) and Latin America (RedCLARA). This link facilitates collaborative efforts among academic communities, including Scientific Collaboration on Climate Change, Advanced Computing System for Latin America and the Caribbean (SCALAC) and University Telemedicine Network (RUTE-AL)
Additionally, we will delve into the efforts of the Latin American Strategy Forum for Research Infrastructure (LASF4RI), dedicated to formulating a strategic framework for advancing research infrastructures in high-energy physics, Cosmology, and Astroparticle Physics. This initiative led, in November 2021, to the Latin American Association for High Energy Physics, Cosmology and Astroparticle Physics (LAA-HECAP) aimed at consolidating and expanding the momentum in research within these fields.
We will also detail LA-CoNGA physics, an ERASMUS+ initiative focused on modernising university infrastructure and enhancing pedagogical offerings in advanced physics. This exemplifies a collaboration between Europe and Latin America to train the next generation of HECAP physicists through a virtual teaching and research network involving three European universities and eight in Latin America, as well as scientific and industrial partners.
Finally, we will explore strategies for aligning these initiatives with the needs and aspirations of the Astronomy, Astrophysics, and Space Science community in Latin America.
Chair: Carlos Román
#598 |
Empowering Latin American Research: Initiatives in Particle Physics, Astroparticle, and more
Luis A. Núñez
1
1 - Escuela de Física, Universidad Industrial de Santander.
Resumen:
Experimental particle physics and Astrophysics are global endeavours out of necessity. The sheer scale of designing, constructing, and operating immense equipment, along with managing and analysing vast data sets, often demands the collaboration of hundreds or even thousands of individuals, alongside funding from numerous nations. Participation in these endeavours offers individuals, institutions, and countries access to valuable training, cutting-edge technology, and a wealth of knowledge. However, becoming fully integrated into international experimental research efforts is a process that often spans generations.
During this presentation, we will provide an overview of various initiatives underway in Latin America. One is the BELLA initiative, establishing a state-of-the-art transcontinental fibre optic connecting research and education networks of Europe (GÉANT) and Latin America (RedCLARA). This link facilitates collaborative efforts among academic communities, including Scientific Collaboration on Climate Change, Advanced Computing System for Latin America and the Caribbean (SCALAC) and University Telemedicine Network (RUTE-AL)
Additionally, we will delve into the efforts of the Latin American Strategy Forum for Research Infrastructure (LASF4RI), dedicated to formulating a strategic framework for advancing research infrastructures in high-energy physics, Cosmology, and Astroparticle Physics. This initiative led, in November 2021, to the Latin American Association for High Energy Physics, Cosmology and Astroparticle Physics (LAA-HECAP) aimed at consolidating and expanding the momentum in research within these fields.
We will also detail LA-CoNGA physics, an ERASMUS+ initiative focused on modernising university infrastructure and enhancing pedagogical offerings in advanced physics. This exemplifies a collaboration between Europe and Latin America to train the next generation of HECAP physicists through a virtual teaching and research network involving three European universities and eight in Latin America, as well as scientific and industrial partners.
Finally, we will explore strategies for aligning these initiatives with the needs and aspirations of the Astronomy, Astrophysics, and Space Science community in Latin America.
15:20 - 16:00
COFFEE BREAK
16:00 - 17:30
J: Galaxies and Cosmology
AGN / Supermassive Black Holes
#283 |
Ionized gas outflows vs. maintenance mod feedback in MaNGA AGN
Lara Gatto
1
;
Thaisa Storchi Bergmann
1
1 - Universidade Federal do Rio Grande do Sul.
Resumen:
We present a study the ionized gas kinematics of 298 Active Galactic Nuclei (AGN) host galaxies as compared to that of 485 control galaxies from the MaNGA-SDSS survey using measurements of the [O\,{\sc III}]$\lambda$5007\AA\, emission line profiles, fitted with one narrow Gaussian component and, for 45\%\ of the sources with one additional broad component. We present flux, velocity and W$_{80}$ maps, comparing them between AGN hosts and controls. The median difference in the $W_{80}$ values between AGN and controls is 238\,km\,s$^{-1}$. We identify "kinematically disturbed regions" (KDRs) within the Extended Narrow Line Region (ENLR) of the AGN, characterized by W$_{80} \ge W_{80,cut}=315$\,km\,s$^{-1}$ -- the mean value for the controls plus its standard deviation. The extent of the KDR R$_{KDR}$ ranges from 1 to 10\,kpc, with a mean ratio to that of the ENLR R$_{ENLR}$ of 55\%. We find a positive correlation between $\langle$W$_{80}\rangle$ and L[O{\sc III}] for the AGN, but, unexpectedly, also for the control sample, suggesting the possible presence of faint AGN in the control galaxies. We estimate the ionized gas mass outflow rate ($\dot{M}_{out}$) and the corresponding kinetic powers ($\dot{E}_{out}$) assuming that the KDR is due to an AGN outflow. Using two methods to obtain the outflow velocity --- one based on W$_{80}$ and the other using the velocity of the broad component, we find kinetic powers for the outflows that correlate with the AGN luminosity $L_{bol}$, populating the low luminosity region of this known correlation. This correlation corresponds to a coupling efficiency between the outflow power and AGN luminosity of 0.01\% and lower. But the large extent of the KDR, in spite of this low coupling efficiency, shows that even low-luminosity AGN, as those of our sample, can impact the host galaxy in a low, ``maintenance mode" feedback.
#466 |
First observation of double-peaked OI emission in the near-infrared spectrum of an active galaxy
Denimara Dias dos Santos
1
;
Alberto Rodríguez-Ardila
2
;
Swayamtrupta Panda
2
;
Murilo Marinello
2
1 - Instituto Nacional de Pesquisas Espaciais.
2 - Laboratório Nacional de Astrofísica.
Resumen:
Double-peaked profiles observed in active galactic nuclei (AGNs) are signs of the presence of a disk-like geometry for the broad line region (BLR). These profiles are generally identified in the optical region in the Balmer lines, and in the ultraviolet (UV) in the Mg\,{\sc ii}\,$\lambda$2798. These spectral features allow us to obtain valuable insights into the geometry of the BLR since the region is not yet spatially resolved. In this work, we detected for the first time a double-peaked emission line in the O\,{\sc i}~$\lambda$11297 profile, in the near-infrared (NIR) spectrum of the local Seyfert 1 galaxy, III~Zw~002. This finding expands our understanding of double-peaked profiles beyond traditional optical and UV lines. In addition to O\,{\sc i} we observe a double-peaked emission in the Pa~$\alpha$ line simultaneously. This is the first case of detecting multiple broad double-peaked NIR emission lines together in an AGN. To investigate the properties of the emitting region, we employ a disk model and an additional Gaussian component attributed to non-disk clouds, namely the classical BLR, to adjust the line profiles. From this procedure, we obtained important parameters, such as the inclination and geometry of the disk, allowing us to estimate the mass of the supermassive black hole in this source. Based on our findings, we suggest that the O\,{\sc i} emission for III~Zw~002 comes from a flattened, low-ionization line-emitting region, providing insight into the complex BLR geometry within the challenging context of active galaxies.
#185 |
Probing the rapid formation of black holes and their Galaxy hosts in QSOs
Karla Alejandra Cutiva Alvarez
1
;
Roger Coziol
1
;
Juan Pablo Torres Papaqui
1
1 - Universidad de Guanajuato.
Resumen:
\begin{abstract}
Using the modelling code X-CIGALE, we reproduced the SEDs of 1,359 SDSS QSOs within the redshift range $0 < z < 4$, for which we have NIR/MIR fluxes with the highest quality and spectral data characterizing their SMBHs. Consistent with a rapid formation of the host galaxies, the star formation histories (SFHs) have small e-folding, at most 750 Myrs using an SFH function for Spiral or 1000 Myrs using one for Elliptical. Above $z \sim 1.6$, the two solutions are degenerate, the SEDs being dominated by the AGN continuum and high star formation rates (SFRs), typical of starburst galaxies, while at lower redshifts the starburst nature of the host, independent from its morphology, is better reproduced by an Spiral SFH. In general, the SFR increases with the redshift, the mass of the bulge, the AGN luminosity and Eddington ratio, suggesting there is no evidence of AGN quenching of star formation. Comparing the specific BHAR with specific SFR, all the QSOs at any redshift trace a linear sequence below the Eddington luminosity, in parallel and above the one-to-one relation, implying that QSOs are in a special phase of evolution during which the growth in mass of their SMBH is more rapid than the growth in mass of their galaxy hosts. This particular phase is consistent with a scenario where the galaxy hosts of QSOs in the past grew in mass more rapidly than their SMBHs, suggesting that a high star formation efficiency during their formation was responsible in limiting their masses.
\end{abstract}
#302 |
Unveiling Spectroscopic Confirmation and Characterization of Bright Galaxies at $\gtrsim$ 8 with JWST
Sofía Rojas-Ruiz
1
;
Micaela Bagley
2
;
Guido Roberts-Borsani
3
;
Steven Finkelstein
2
;
Tommaso Treu
1
;
Pablo Arrabal Haro
4
;
Eduardo Bañados
5
;
Oscar Antonio Chavez Ortiz
2
;
Katherine Chworowsky
2
;
Taylor Alexandra Hutchison
6
;
Rebecca Larson
7
;
Nicha Leethochawalit
8
;
Gene Leung
2
;
Charlotte Mason
9
;
Takahiro Morihista
10
;
Rachel Somerville
11
;
Michele Trenti
12
;
Aaron Yung
13
1 - University of California, Los Angeles.
2 - The University of Texas at Austin.
3 - University of Geneva.
4 - AURA/NOIRLab.
5 - Max Planck Institute for Astronomy.
6 - NASA Goddard Space Flight Center.
7 - Rochester Institute of Technology.
8 - National Astronomical Research Institute of Thailand.
9 - University of Copenhagen / DAWN.
10 - Caltech/IPAC.
11 - Rutgers University/ Flatiron Institute.
12 - University of Melbourne.
13 - Space Telescope Science Institute.
Resumen:
The abundance of UV-bright galaxies at redshift $z > 8$, or within the first $\sim$600 Myrs, can provide key constraints on galaxy evolution models and the epoch of reionization, as the predicted abundance varies greatly when different physical prescriptions for gas cooling and star formation are implemented. The Hubble Space Telescope (HST) has been used to find such bright galaxies in deep surveys but in a focused patch of the sky, making the known galaxy population highly affected by cosmic variance effects. Pure parallel programs -- where random field pointings result in completely independent, uncorrelated observations -- provide an excellent opportunity to observe a population of rare bright sources that may not be fully sampled by deep surveys covering the same area in contiguous fields. Galaxy candidates from the HST surveys of superBoRG, BoRG, HIPPIES, and WISP comprise the largest pure-parallel sample including some of the brightest candidates at these redshifts, potentially representing some of the most massive galaxies to form at $< 600$ Myr. We are leading JWST/NIRSpec observations from Cycle 1 programs GO 1747 and GO 2426 to spectroscopically confirm these galaxy candidates. We have 9 out of 21 targets already observed with low-resolution Prism spectroscopy. Here, we will present the so far four galaxy confirmations via the detection of the Lyman break, and their ionizing power through the characterization of the [OIII]/[OII] line ratio (see e.g. Fig 1). We expect to present more results as observations arrive by the time of the conference meeting. The resulting observed density of UV-bright galaxies from our study will provide important constraints on models of star formation efficiency to some of the earliest-probed redshifts ($z > 10$), as well as chemical and ionizing characterization of galaxies deep into the epoch of reionization.
#462 |
Dusty star-forming galaxies as tracers of protoclusters: A simulated perspective
Pablo Araya Araya
1
;
Rachel Cochrane
2
;
Christopher Hayward
2
;
Douglas Rennehan
3
;
Laerte Sodré Jr.
1
;
Robert Yates
4
;
Roderik Overzier
5
;
Marcelo Vicentin
1
1 - Universidade de São Paulo.
2 - Flatiron Institute (CCA).
3 - Flatiron Institute.
4 - University of Hertfordshire.
5 - Observatório Nacional.
Resumen:
Dusty star-forming galaxies (DSFGs) are commonly used as tracers of galaxy protoclusters, with many spectacular examples identified with telescopes such as the South Pole Telescope, Planck, and Herschel. However, to date, there has been relatively little 'first principles' theoretical work that models the connection between DSFGs and protoclusters. To address this gap, we have incorporated scaling relations (derived in previous work by performing radiative transfer calculations on hydro simulations) to predict far-IR/submm flux densities into the L-Galaxies semi-analytic model. I will present a few results from this new model. Specifically, I will show that protocluster cores exhibit an excess of DSFGs relative to protocluster 'outskirts' and the field. However, contrary to some claims in the literature, this is not due to the dense environment 'triggering' starbursts. Rather, the DSFGs typically lie near the star formation main sequence. The reason for the excess is that protocluster cores have an excess of massive galaxies relative to less-overdense regions. Moreover, the model predicts that the brightest DSFGs are predominantly located in protocluster cores.
#028 |
The relation between globular cluster systems and supermassive black holes in spiral galaxies III. The link to the $M_\bullet - M_\ast$ correlation.
Rosa A. Gonzalez Lopez Lira
1
;
Luis Lomelí-Núñez
2
;
Yasna Ordenes-Briceño
3
;
Laurent Loinard
1
;
Stephen Gwyn
4
;
Karla Alamo-Martínez
5
;
Gustavo Bruzual
1
;
Ariane Lançon
6
;
Thomas Puzia
3
1 - UNAM.
2 - Universidade Federal do Rio de Janeiro.
3 - Pontificia Universidad Católica de Chile.
4 - Herzberg Institute of Astrophysics.
5 - Universidad de Guanajuato.
6 - Université de Strasbourg.
Resumen:
We continue to explore the relationship between globular cluster total number,
$N_{\rm GC}$, and central black hole mass, $M_\bullet$, in spiral galaxies. We
present here results for the Sab galaxies NGC\,3368, NGC\,4736 (M\,94) and
NGC\,4826 (M\,64), and the Sm galaxy NGC\,4395. The globular cluster (GC)
candidate selection is based on the (u* - i') versus (i' - Ks)
color-color diagram, and i'-band shape parameters. We determine the
$M_\bullet$ versus $N_{\rm GC}$ correlation for these spirals, plus NGC\,4258,
NGC\,253, M\,104, M\,81, M\,31, and the Milky Way (i.e., we have doubled the
previously existing sample of spirals with both $M_\bullet$ and $N_{\rm GC}$
measurements). We also redetermine the correlation for the elliptical sample in
Harris et al. (2014), with updated galaxy types from Sahu et al. (2019). Additionally,
we derive total stellar galaxy mass, $M_\ast$, from its two-slope correlation with
$N_{\rm GC}$ (Hudson et al. 2014), and fit $M_\bullet$ versus $M_\ast$ for both
spirals and ellipticals. We obtain log$M_\bullet \propto$ (1.01 $\pm$ 0.13) log $N_{\rm GC}$
for ellipticals, and log $M_\bullet \propto$ (1.64 $\pm$ 0.24) log $N_{\rm GC}$ for
late type galaxies (LTG). The linear $M_\bullet$ versus $N_{\rm GC}$ correlation in
ellipticals could be due to statistical convergence through mergers, but not the much
steeper correlation for LTG. However, in the $M_\bullet$ versus total stellar
mass ($M_\ast$) parameter space, {\it with $M_\ast$ derived from its
correlation with $N_{\rm GC}$}, log $M_\bullet \propto$ (1.48 $\pm$ 0.18) log
$M_\ast$ for ellipticals, and log $M_\bullet \propto$ (1.21 $\pm$ 0.16) log
$M_\ast$ for LTG. The observed agreement between ellipticals and LTG in this
parameter space may imply that black holes and galaxies co-evolve through
``calm” accretion, AGN feedback, and other secular processes.
17:30 - 17:45
CLOSURE
FOYER
Poster Group II - DISPLAY
Poster Group II - REMOVAL
SALÓN ROJO (150)
10:20 - 11:00
COFFEE BREAK
11:00 - 11:45
B: Facilities, Technologies and Data Science
Techniques and Instruments
Chair: Eleonora Sani
#414 |
Airglow vs. Skyglow: a portable optical spectrograph for the analysis of natural and artificial light at night
Juan Pablo Uchima-Tamayo
1
;
Rodolfo Angeloni
2
;
Marcelo Jaque
1
1 - Universidad de La Serena.
2 - Gemini Observatory, NSFs NOIRLab.
Resumen:
The detrimental effects of light pollution on astronomy, ecology, and human health are intimately linked to the development, and subsequent misuse, of the rapidly evolving lighting technology. Because of the so-called LED revolution, in the course of the last decade, the Spectral Power Distribution (SPD) of man-made light pollution has been shifting from one containing a few emission lines to one containing dozens - if not hundreds - of lines, along with a significantly increased continuum level in the blue-green spectral range. Because of this SPD reshaping, there is ever growing evidence that most of the photometric technologies and techniques that have so far been used to monitor light pollution worldwide are not able to cope with the massive and fast spread of LED sources. Therefore, the only way to make a significant leap forward in the quantitative characterization of this phenomenon is through spectroscopy, a technique capable not only of disentangling the different contributions to the Night Sky Brightness (NSB), but also of following its complex, multiperiodic variability.
In this talk, I will introduce our interdisciplinary project aimed at developing a portable optical spectrograph for the first-ever spectral monitoring of the Chilean night sky. This device will be capable of capturing low-resolution flux-calibrated spectra of large sections of the celestial sphere at once. With its lightweight, modular, and versatile design, it will enable a comprehensive spectral characterization of both natural and artificial sources of NSB. We will eventually gain an accurate understanding of how light pollution affects the upper half of the Chilean horizon, a natural and cultural heritage that is our scientific, social, and moral obligation to protect and preserve.
#298 |
BOCOSUR: an all sky network for fireball detection in Uruguay
Manuel Caldas
1
;
Alvaro Guaimare
1
;
Valeria Abraham
1
;
Lucas Barrios
1
;
Matías Hernández
1
;
Lucía Velasco
1
;
Gonzalo Tancredi
1
1 - Dpto. Astronomía, Facultad de Ciencias.
Resumen:
During the last decade several networks for automatic detection of fireballs have been deployed, with the main scientific goal of enabling a rapid recovery of meteorites and determination of its parent's pre-atmospheric orbit. The geographical distribution of these networks is heavily biased towards the Northern hemisphere. The Bocosur network is a contribution to the global deployment of automated fireball networks, and particularly to the unbiasing of their geographical distribution, since it is located in Uruguay, South America (Lat: -30° to -35°). Its main scientific goal is the detection of fireballs of asteroidal origin, massive enough to produce meteorites, and also to inspire secondary-level students and teachers through their involvement in this citizen-science oriented project. The deployment of this network started in 2019, and was completed in March, 2023, when we installed 20 stations separated ~120 km, covering an area of ~ 180,000km2. During this period of time, one major technological upgrade was made when we migrated from a well-known camera to a higher-resolution, more sensitive system. We were able to build a completely autonomous system at an affordable cost that can be replicated in all the stations. A comparison between the astrometric and photometric performance of these two detection systems is reported. Also, a photometric methodology for estimating the brightness of very bright fireballs is presented and validated against the known magnitudes of Jupiter and the full Moon. We obtain mean residuals of the astrometric reduction of ~5', and the discrepancy between the obtained brightness of Jupiter and the Moon average to 0.18 and 1.0 magnitudes, respectively.
#353 |
Semi-Supervised Domain Adaptation for Multi-band Photometric Supernovae Classification
Jorge Saavedra-Bastidas
1
;
Daniel Moreno-Cartagena
2
;
Manuel Pérez-Carrasco
3
;
Guillermo Cabrera-Vives
2
1 - Astronomy department, Universidad de Concepción.
2 - Department of Computer Science, Universidad de Concepción.
3 - Data Science Unit, Universidad de Concepción.
Resumen:
The transient objects known as supernovae constitute one of the most exciting laboratories of study in various areas of astronomy because of their involvement in different physical processes. The large influx of current data leads us to search for new ways to correctly classify these objects in the shortest amount of time possible, even when reliable labels are scarce. In this paper, we present a novel approach that extends the Minimax Entropy semi-supervised learning algorithm to the classification of multiband time series data and tests it on observational light curves of different supernova categories obtained by forced photometry from the Zwicky Transient Facility (ZTF). We quantify the performance of our classifier according to the number of real supernova light curves delivered during the learning period as well as the evolution of its performance based on the number of observations per supernova available when predicting with new data. Our results show that the classification accuracy improves over the lifetime of the transient as more photometric data become available. We demonstrate the ability of our model to provide early classifications of observed transients from the ZTF data stream compared to fully supervised classification models.
11:45 - 12:30
D: High Energy Phenomena and Fundamental Physics
Gamma-Ray Sources and Cosmic Rays
Chair: Eleonora Sani
#547 |
Machine Learning Explorations in GRB Studies: From Classification to Extended Emission Identification
Keneth Garcia-Cifuentes
1
;
Rosa Leticia Becerra Godinez
2
;
Fabio De Colle
2
1 - Universidad Nacional Autónoma de México.
2 - Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares.
Resumen:
Gamma-ray bursts (GRBs) have traditionally been categorized based on their durations. However, the emergence of extended emission (EE) GRBs, characterized by durations higher than 2 seconds and properties similar to short GRBs, challenges conventional classification methods. In this talk, we delve into GRB classification, focusing on a non-supervised machine-learning technique (t-distributed stochastic neighbor embedding, t-SNE) for classification and the identification of extended emission in GRBs.
Furthermore, we introduce an innovative tool, ClassipyGRB, designed for astronomers whose research centers on GRBs. This versatile Python3 module enhances the exploration of GRBs by offering interactive visualizations of their light curves and highlighting shared attributes. With ClassipyGRB, astronomers can swiftly compare events, identifying resemblances and exploring their high-frequency characteristics. This tool uses the power of proximity analysis, enabling rapid identification of similar GRBs within seconds.
#086 |
On the origin of the unidentified $\gamma$-ray source in NGC 2071
Agostina Filócomo
1
;
Juan Facundo Albacete Colombo
1
;
Enrique Mestre
2
;
Leonardo Javier Pellizza
3
;
Jorge Ariel Combi
4
1 - Universidad Nacional de Río Negro.
2 - Institute of Space Science.
3 - Instituto de Astronomía y Física del Espacio.
4 - Instituto Argentino de Radioastronomía.
Resumen:
NGC 2071 is a star-forming region positionally correlated with three unidentified $\gamma$-ray sources detected by the \textit{Fermi} satellite telescope. According to preliminary models, T-Tauri stars could produce $\gamma$-ray emission under specific conditions. We performed a spectral and temporal analysis of the \textit{Fermi} data to determine whether the detected emission was caused by flares occurring in T-Tauri stars. We found that the $\gamma$-ray source can only be detected in the first two years of observations at energies above 100~GeV. In addition, a variability analysis reveals that the expected frequency of events is compatible with flare activity with a minimum X-ray energy of $5 \times 10^{37}~\text{erg}$. These observational results impose, for the first time, a substantial constraint on the energetic of flares in T-Tauri stars that could explain the origin of unknown $\gamma$-ray sources in star-forming regions.
#409 |
Massive Star Clusters as Galactic Accelerators of Cosmic Rays
Maria Victoria del Valle
1
1 - Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo (IAG/USP).
Resumen:
In recent years, massive stellar clusters have received renewed attention as possible contributors to the Galactic component of cosmic rays. The collective action of stellar winds forms superbubbles, which are large, multi-parsec structures. The interacting stellar winds supply large amounts of kinetic energy that could be used to accelerate cosmic rays up to very high energies. The particles interact with the surrounding material producing gamma rays. In this work we study the particle acceleration and interactions in super bubbles produced by the collective interactions of massive young stars. We model the gamma-ray emission expected from these interactions and constrain the production of cosmic rays. We also analyze the observability of the modeled sources by gamma-ray observatories.
12:30 - 14:30
LUNCH
15:20 - 16:00
COFFEE BREAK
16:00 - 17:30
B: Facilities, Technologies and Data Science
Surveys, Instruments and Facilities
Chair: Anthony Brown
#445 |
SCORPIO a new facility instrument for Gemini South
The Scorpio Team
1
;
Ruben Diaz
1
1 - Gemini Observatory, NSF$^\prime$s NOIRLab.
Resumen:
SCORPIO, the new Gen4\#3 facility instrument for the Gemini
South telescope, will provide imaging and spectroscopy in
eight wavelength
bands simultaneously from 0.4 to 2.2 microns. SCORPIO will be
extremely versatile in addressing fore$-$front science cases ranging
from Solar System studies to extragalactic astrophysics and will
play a leading role in Gemini follow$-$up of time$-$domain events
triggered by large$-$scale surveys. The instrument is currently
in its Assembly, Integration and Verification phase and is
expected to be commissioned at Cerro Pachon during semester
2025A and offered to the Gemini user community starting in
2025B. In this talk, I$^\prime$ll be reviewing SCORPIO$^\prime$s
history, motivation, and final design, describe the expected
performance in the context of its driving science cases,
and summarize how it will be integrated in the Gemini TDA
projects and operations.
#532 |
The LLAMA Observatory
Jacques R.D. Lepine
1
;
Ricardo F. Trindade
2
;
Danilo Zanella
3
;
Andrey Baryschev
4
;
Fatima Salete Correra
5
;
Marcos Aurelio Luqueze
6
;
Antonio Verri
5
;
Wesley Beccaro
5
;
Ciriaco Goddi
7
;
Tania Dominici
8
;
Cesar Strauss
9
;
Luiz Reitano
10
;
Guillermo G. de Castro
11
;
Jean Pierre Raulin
11
;
Paula Benaglia
12
;
Manuel Fernandez
12
;
Juan José Larrarte
12
;
Guillermo Gancio
12
;
Silvina Cichowolski
13
;
Carlos Valotto
14
;
Ricardo Finger Camus
15
;
Emiliano Rasztocky
12
;
Rodrigo Reeves
16
1 - IAG- Universidade de São Paulo.
2 - Universidade de São Paulo.
3 - IAG-Universidade de São Paulo.
4 - University of Groningen.
5 - Escola Politécnica Universidade de São Paulo.
6 - Escola Politécnica Universidade de São Paulo.
7 - IAG Universidade de São Paulo.
8 - INPE Instituto de Ciências Espaciais.
9 - INPE (Instituto Nacional de Ciências Espaciais).
10 - INPE (Instituto Ncional de Ciências Espaciais).
11 - Universidade Mackenzie.
12 - Instituto Argentino de Radioastronomia.
13 - IAFE (Instituto de Astronomia y Fisica del Espacio).
14 - CONICET Universidad de Cordoba.
15 - Das. -Universidad de Chile.
16 - CePia Universidad de Concepción.
Resumen:
The LLAMA Observatory, in the Argentinian Andes at 4800m altitude, in the Salta province, is a project of Argentina and Brazil, which started in 2014 with an agreement between FAPESP ( research foundation of Sao Paulo State), University of São Paulo, and MinCyt ( Ministry of Science and technology of Argentina. The expenses will be equally shared. The 12m diameter antenna was constructed by VERTEX Antennentechnik GmbH (Duisburg, Germany). The surface precision of the dish will reach 15 microns r.m.s. deviations from an ideal parabola, after a period of fine adjustments. The antenna will perform observations at mm and sub-mm radio waves, like the international ALMA interferometer. The LLAMA antenna will be equipped with two lateral Nasmith cabins, similarly to the APEX antenna. Initially, we will work with receivers band 5, band 6 and band 9 (band names of the ALMA observatory), constructed at NOVA Labs (University of Groningen, Holland). Brazil contributed to the acquisition of receivers and construction of sub-systems , like the optomechanical system to be installed inside the Nasmith and Cassegrain cabins, the cryogenics, and cryostat,where the receivers will be installed. and a system for holography.
The mounting of the antenna, which was slow in last years is going quite rapidly now, after Mincyt attributed to INVAP, a strong engineering and technological company, the task of mounting. It is predicted that the mounting will be concluded in March 2024, and the first light will happen 2 years later.
The main scientific uses will be in the following areas: Galaxy Formation in the Early Universe; Astrochemistry: molecular evolution of interstellar clouds; Identification of unknown lines; Extra-solar planets and proto-planetary disks; polarimetry of radio sources and of the Interstellar Medium; Solar Physics (few antennas at this frequency can be pointed towards the Sun, like LLAMA).
#520 |
Radio telescopes for Mexico and Latin America
Stan Kurtz
1
;
David Gale
2
1 - IRyA, UNAM.
2 - INAOE.
Resumen:
Inspired by similar efforts in Asia, Australia and Africa, we have
undertaken an effort in Mexico to convert a retired telecommunications
antenna into a radio telescope. The Tulancingo-1 antenna is a 32-meter
parabolic dish, located at the Tulancingo Earth Station in the Mexican
state of Hidalgo. When fully operational, we anticipate an operational
frequency range of 1 to 15 GHz, and possibly as high as 23 GHz. Here, we
describe the current state of the conversion project, mention several of
the many potential science applications of the telescope, and extrapolate
our experience to what might be achieved by a Latin American network of
radio telescopes, based on similarly converted antennas.
#421 |
What is this? WIT objects and serendipity in the VVV/VVVX survey
Dante Minniti
1
1 - UNAB/VO/UFSC.
Resumen:
The VVVX survey (VVV extended) have been monitoring the Galactic bulge and southern disk in the near-IR using the VISTA telescope at ESO Paranal Observatory for a dozen years. We have carried out massive searches for variable stars, resulting in the discovery of many many thousands of variable sources of all kinds (eclipsing binaries, RR Lyrae, Miras/LPVs, delta Scuti stars, classical Cepheids, type 2 Cepheids, novae, microlensing events, etc). Interestingly, some objects that defy classification have also been found within our database. These are called WIT objects (short for What Is This?). Upon closer inspection, in the end some of these WITs turn out to be observational glitches, or to fit into the previously known kinds of objects, but that are observed through extreme conditions like very high extinction. However, a few of them appear to be new astrophysical phenomena. I will discuss some specific cases of previously unclassified variable sources that have been discovered by the VVV near-IR survey. They a wide variety of extreme or rare astrophysical phenomena, including light echoes, eruptive YSOs, protostellar colissions, dusty novae, Tabby stars, eclipses by a dark disk, violently variable AGNs, etc. I will describe our searches and also the different follow-up observations that are needed to properly properly characterize these sources, and how to take into account serendipity in future surveys.
SALÓN DORADO (120)
10:20 - 11:00
COFFEE BREAK
11:00 - 12:30
G: Stars and Stellar Physics
Stellar Structure and Evolution II
Chair: Julia Arias
#053 |
Lithium depletion in solar analogs: age, mass, and planet effects
Anne Rathsam
1
;
Jorge Meléndez
1
;
Gabriela Silva
1
;
Giulia Martos
1
1 - Universidade de São Paulo.
Resumen:
Lithium is an essential element for Stellar Astrophysics because it is depleted at somewhat low temperatures which are easily reached in the interior of stars. According to standard models, the base of the convection zone of main sequence solar-type stars does not reach deep enough inside the star to burn Li. However, it is observed that older field solar analogs present a lower Li content, indicating that part of the Li present in the stars is taken towards inner regions through non-standard mixture processes. In this work, we determined Li abundances for a sample of 153 solar analogs, exploring the dependence of Li with age, mass and convective mass. The high-quality (R $=$ 115000; 270 $\leq$ SNR $\leq$ 1000) spectra used in this project were taken with ESO’s HARPS spectrograph. We employed the method of high precision differential spectroscopy, measuring equivalent widths of spectral lines to determine atmospheric parameters and infer masses and ages. The Li abundance was determined via spectral synthesis. We found a strong correlation between lithium abundance and age, and also a clear link between low lithium abundances and lower masses (and higher convective masses). We added another high-precision HARPS sample of solar analogs studied in our group to consider the effect of planets on Li in a sample of 194 stars and we report that planet hosts have on average Li abundances -0.3 dex lower than non-planet hosts with similar parameters, with a significance above 99\% for our results.
#068 |
Multiple Element Abundance Fitting Software, MEAFS
Matheus J. Castro
1
;
Heitor Ernandes
2
;
Beatriz Barbuy
1
1 - Institute of Astronomy, Geophysics and Atmospheric Sciences of the University of São Paulo.
2 - Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University.
Resumen:
Deriving chemical abundances from spectra is one of the great jobs in astronomy. The chemical evolution of the Galaxy can be studied through the abundance of chemical elements of stars of different stellar populations. The applications are diverse, deriving abundances in a spectrum can help us predict, for example, which is the future of stars like the Sun will be like. Each star has a chemical signature depending on the conditions of its formation, its mass and age.
The analysis is a job that demands time and precision. Commonly, for a robust work, it is necessary to analyse hundreds of spectral lines, which can take days or months to adjust all of them. For each line, it is necessary to run programs that generate synthetic spectra of stars several times, changing the chemical abundance of the element being analysed in order to better fit the model with the observed spectrum.
MEAFS (Multiple Element Abundance Fitting Software) is a code being developed in \textit{Python} and \textit{C} that aims to fit abundances automatically and for multiple elements in a single execution. It is also able to adjust the convolution, the continuum and the wavelength shift of the synthetic spectrum for the best fit with the observed spectrum. Not only does it faster than the manual way, it is in principle also more accurate than an average person.
The code is under development and currently MEAFS can run the \textit{Turbospectrum} (Plez, 2012) spectrum generator. The version to use the code \textit{PFANT} (Barbuy et al., 2018) is aso in progress.
The current version with \textit{Turbospectrum} was tested with spectra of the star CS 31082-001 and the analysis of 260 spectral lines takes around two hours. The code is validated for clear and unblended lines as shown in Ernandes et al. (2023).
#508 |
New insights on weak winds in massive stars from hydrodynamical simulations
Elisson Saldanha da Gama de Almeida
1
;
Michel Curé
1
;
Catalina Arcos
1
;
María Laura Arias
2
;
Marcelo Borges Fernandes
3
;
Wagner Marcolino
4
;
Lydia Cidale
2
1 - Instituto de Física y Astronomía/Universidad de Valparaíso.
2 - Instituto de Astrofísica de La Plata (CONICET-UNLP).
3 - Observatório Nacional.
4 - Observatório do Valongo/Universidade Federal do Rio de Janeiro.
Resumen:
Although the theoretical bases of line-driven winds were set around half a century ago, it is still uncertain what are the real mass-loss rates among different luminosity classes of O stars. One severe issue is the so-called weak wind phenomenon, where the empirical mass-loss rates ($\dot{M}$) of late O stars (O8-9V and O8-9III) are lower by $10^{2}$ than theoretical predictions from Vink’s mass loss recipe. In this work, we present our ongoing results on weak winds in late O dwarfs and giants using hydrodynamical simulations with the code HYDWIND. These hydrodynamical results are used as input parameters in state-of-the-art non-LTE radiative transfer codes, CMFGEN and FASTWIND, to calculate synthetic spectra and test them against observations in the UV and visible regions. In Fig. 1, we show our preliminary results based on H$\alpha$ spectroscopy for the weak wind star HD 46202 (O9V). The observed H$\alpha$ line profile is well reproduced using both codes with the solved hydrodynamics by HYDWIND. This happens when we consider the last fast wind solution, that is, increasing the value of the line-force parameter $\delta$ (from the CAK-theory) before obtaining a $\delta$-slow wind solution ($\delta >$ 0.25-0.30). In this case, our derived $\dot{M}$ for this star is $\sim$$3\mathrm{E}{-10}$ $M_\odot$ yr\textsuperscript{-1} (weak wind regime). For comparison, this value is about $10^{2}$ lower than the one from Vink’s mass loss recipe. In conclusion, these results indicate that weak winds could be explained from first principles (solving the wind motion equation), deserving additional constraints from spectral regions other than the UV and visible. We also discuss our perspectives of exploring weak winds in the infrared region, especially using the Br$\alpha$ line profile, since we had allocated time to observe late O dwarfs and giants with the GEMINI/GNIRS and ESO/CRIRES instruments, to be performed during the second semester of 2023.
#366 |
Constraining the physics of rotation in stellar interiors
Facundo Moyano
1
1 - University of Geneva, Switzerland.
Resumen:
Thanks to space-borne missions like Kepler and TESS, and new asteroseismic techniques developed in recent years, the rotation rate in stellar interiors was obtained for hundreds of stars in different evolutionary phases. This revealed a strong disagreement between stellar models and observations, pointing to a missing physical process in stellar evolution models with rotation. The treatment of rotation in stellar interiors affects both the transport of angular momentum and chemical elements, and hence can change several outputs of stellar models such as the surface chemical composition, surface rotational velocities, and even affect the predicted rotational periods of neutron stars and spins of black holes. Therefore improving our understanding of angular momentum transport processes in stellar interiors is fundamental to improve stellar models and make better predictions. In this talk I will review the status of the problem with emphasis on recent constraints obtained with asteroseismic techniques and its interplay with spectroscopic data. I will then present the main physical candidates proposed to solve the inconsistency between models and observations, with particular emphasis on magnetic fields present in stellar interiors.
#330 |
Pulsating stars in the inner Galactic VVV globular clusters
Javier Alonso-García
1
1 - Universidad de Antofagasta / MAS.
Resumen:
The globular clusters in the innermost regions of the Milky Way are affected by high, differential extinction. Their physical parameters are therefore not as reliably measured as their counterparts of the outer halo. Extinction effects are highly diminished in near-infrared observations, like the ones provided by the Vista Variables in the Via Lactea (VVV) survey and its extension, the VVV-X. More than 50 known Galactic globular clusters located towards the inner Milky Way lie in the region surveyed by the VVV and the VVV-X. Their multi-epoch observations allow us to search and characterize the pulsating stars contained in these star clusters. The tight near-infrared period-luminosity-metallicity relations of these variable stars allow a better parametrization of the globular clusters to which they belong. In my contribution, I will present our current, ongoing analyses of the pulsating stars in some of these poorly known objects within the framework of the VVV and VVV-X.
12:30 - 14:30
LUNCH
15:20 - 16:00
COFFEE BREAK
16:00 - 17:30
D: High Energy Phenomena and Fundamental Physics
Gamma Rays, Black Holes, and Neutron Stars
Chair: Luis Núñez
#067 |
Simulations of the long-term magnetic field evolution in neutron star cores
Francisco Castillo
1
;
Mikhail Gusakov
2
;
Juan Alejandro Valdivia
3
;
Andreas Reisenegger
1
1 - Universidad Metropolitana de Ciencias de la Educación.
2 - Ioffe Institute.
3 - Universidad de Chile.
Resumen:
The evolution of the magnetic field in neutron stars is strongly related to their internal structure. In the NS core, there is a fluid mixture of neutrons, protons, and electrons (joined by other species at increasing densities) that scatter off each other through strong and electromagnetic interactions, causing effective friction forces, and can also convert into each other by weak interactions (‘‘Urca reactions’’). Likely, the dominant process evolving the magnetic field there is ambipolar diffusion, i.e., the joint motion of the charged particles and the magnetic field relative to the neutrons, driven by the Lorentz force and controlled by frictional forces and pressure gradients. Here, we present simulations of the long-term evolution of the magnetic field in the interior of an isolated, axially symmetric neutron star core, under ambipolar diffusion.
Special attention is given to the characterization of the newly developed numerical approach, different physical processes involved, as well as their corresponding timescales, which happen to be in agreement with our numerical estimates.
#304 |
Formation of binary compact objects in young star clusters with PeTar and SEVN
Gastón Escobar
1
;
Giuliano Iorio
1
;
Sara Rastello
1
;
Michela Mapelli
2
1 - University of Padova.
2 - University of Heidelberg.
Resumen:
The currently-growing LIGO-Virgo data provides an excellent opportunity to investigate the demography of gravitational-wave sources and their production channels. Gravitational-waves detected by LIGO-Virgo are originated in the coalescence of two compact objects, as black holes (BHs) or neutron stars (NSs). Compact-object binaries that merge in less than a Hubble time may arise as the last evolutionary stage of binary stars evolved in isolation. In addition, dynamically active and dense environments, such as star clusters, provide several mechanisms to produce or enhance these merger episodes via dynamical channels. Research in this topic is addressed performing population-synthesis simulations of binary systems and direct N-body star-cluster simulations. In this talk we will show our recently developed tool to compute both dynamics and binary evolution integrated together, which uses the group's population-synthesis code SEVN (Stellar EVolution N-body) within the state-of-the-art N-body code PeTar. SEVN uses a set of precomputed stellar tracks to interpolate the evolution of star properties on the fly. This is a change of paradigm in the field, since most population synthesis codes rely on fitting formulas to stellar evolution tracks run more than 20 years ago. We will show our results on the demography of binary compact objects, as binary BHs (BBHs) and BH-NSs, formed in young star clusters ($10^{4-5}~M_{\odot}$), and confront the results with those which use past stellar-evolution prescriptions.
#405 |
The binary black holes of LIGO and Virgo
Javier Roulet
1
1 - California Institute of Technology.
Resumen:
With approximately a hundred detections to date, the discoveries of compact binary mergers by the LIGO and Virgo gravitational-wave detectors have opened a new observational window to the Universe. These data have been made publicly available, enabling their independent analysis by the community. In this talk I will describe various such analyses carried by our group.
A first layer involves searching for signals. We have developed a detection pipeline implementing original solutions to mitigate systematics in the detectors, with which we were able to confirm previous detections and make new ones.
A second stage requires estimating signal parameters (masses, spins, location...). We have developed algorithms to improve the efficiency and robustness of this process, and implemented them in an open-source code `cogwheel`.
Lastly, considering the parameters of all events as a whole we can describe the statistical properties of the observed population of binary black holes and compare against predictions of candidate formation mechanisms. For example, I will show that the observed proportion of events with spins aligned versus anti-aligned with the orbit disfavors the hypothesis that the spin distribution is isotropic.
#011 |
On the formation of NS-NS and NS-BH binaries from binary-driven hypernov
Laura Marcela Becerra
1
;
Jorge Rueda
2
1 - Universidad Industrial de Santander.
2 - International Center of Relativistic Astrophysics.
Resumen:
The binary-driven hypernova (BdHN) model is a proposed explanation for long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe) in which a binary system consisting of a carbon-oxygen (CO) star and a neutron star (NS) companion in close orbit undergoes a series of physical episodes. The event is triggered by the core collapse of the CO star, leading to a supernova (SN) explosion that forms a newborn NS (hereafter $\nu$NS) at its center. The SN accretes at super-Eddington rates on the $\nu$NS and the NS companion, leading to a binary system classified as type I when the NS forms a black hole (BH), type II when the NS becomes only a more massive NS, and type III when the orbital separation is too large for the companion NS to play any role in the GRB. With smooth hydrodynamics simulations, in this work, we investigate the binary parameters that determine whether the $\nu$NS or the NS companion reaches the point of gravitational collapse into a BH during the accretion process, as well as the time it takes for collapse to occur since the SN explosion. We also examine whether the system remains gravitationally bound after the SN explosion, leading to an NS-NS binary in BdHN II, an NS-BH binary in BdHN I, or if it disrupts altogether. We determine the maximum orbital period of the initial CO-NS binary that can remain bound after a BdHN event and calculate the characteristic parameters of the resulting NS-NS binaries.Overall, our findings shed light on the physical mechanisms driving BdHN and provide insight into the potential outcomes of such cataclysmic events in binary systems.
#558 |
Flare-induced feedback on the broad line region, the study case of PKS2004-447
Eleonora Sani
1
1 - ESO - Chile.
Resumen:
PKS2004-447 is a rare hybrid between a gamma-ray emitting narrow-line Seyfert 1 and a compact steep-spectrum radio source.
It harbors a relatively small supermassive black hole accreting at typical NLS1s' Eddington ratio and, as our recent observations show, it connects these two classes of objects in the AGN evolution framework. PKS 2004-447 underwent, for the first time, a gamma-ray flare in 2019 mainly caused by the relativistic jet, which altered the broad line region with a flux excess redshifted by 250 km/s observed in the Balmer, Paschen, and He I permitted lines. This new emission feature was no longer visible 1.5 years later, suggesting a causal connection with the flare. The emission lines coming from the same atomic transition series show a similar velocity offset for this "red excess", but the offset changes for different line series. This discovery suggests that the relativistic jet can affect the physics of the BLR in this peculiar AGN, and that flaring activity can lead to the formation of additional and localized broad emission components. Our results highlight the importance of optical spectroscopy for flaring jetted AGN, and that our understanding of the jet-BLR -connection is still very limited.
#147 |
Binary synthesis of merging compact object populations from evolving initial conditions
Lucas M. de Sá
1
;
Antônio Bernardo
1
;
Riis R. A. Bachega
1
;
Livia S. Rocha
1
;
Jorge E. Horvath
1
1 - Institute of Astronomy, Geophysics and Atmospheric Sciences - University of São Paulo.
Resumen:
Over the past few years, the steadily growing catalog of compact object mergers observed by the LVK Collaboration has allowed for a picture of the properties of these events as a population to start to emerge. One invaluable tool in the exploitation of this growing catalog has been rapid binary population synthesis (BPS), which allows for predictions for the rate of observed mergers and their properties, as well as for constraining the initial conditions of stellar/binary formation and evolutionary models by comparing the results with observations. While much has been done in BPS to constrain the evolutionary models, the initial conditions have been comparatively neglected. Chiefly, this ignores the long-expected trend of the initial mass function (IMF) to become top-heavy at high redshift, i.e., to produce more compact object progenitors. One such model for a varying IMF is the integrated-galaxy wide IMF (IGIMF). In this work, we employ the IGIMF and correlated orbital parameter distributions to perform the population synthesis of compact object mergers with the code COMPAS. We are able to generate populations consistent with star formation rate, metallicity and IMF evolution with redshift, such that we are able to study how observed merger rates and other properties vary with redshift. We find an overall tendency of merging binaries to be more massive the older they are and the higher the merger redshift is. We also find support for a peak in the merger rate of binary black holes (BBHs) between redshift ~2 and ~1. We compare this trend to the current LVK constraints on the merger evolution of the BBH merger rate. Our work provides a framework for redshift-dependent population synthesis broadly speaking, and for testing IMF variations in particular.
