Extragalactic - Galaxies

Title: SDSS-V and ZTF synergy to find real variability in QSO multi-epoch spectra

Bernal, Santiago.

Arévalo, Patricia. Instituto de Física y Astronomía, Universidad de Valparaíso

Abstract: New dedicated spectroscopic surveys like the SDSS-V Black Hole Mapper (BHM) offer a great opportunity to study the evolution of variable objects like Quasars. However, the cadence of the data is not enough to rigorously evaluate the trend of flux changes, and when using big samples (≳10^3) it is difficult to analyze one by one the particular cases. In this context the high cadence data is necessary to confirm real changes and useful to show if spectra were taken in a rising or dropping flux trend, at a local minimum or maximum flux level or at transient major events like flares. Here we present results of the synergy between SDSS-V spectral data and Zwicky Transient Facility (ZTF) Forced Photometry intensive light curves. The comparison of flux trends allows us to flag bogus spectral flux changes that help to spot bad observations or calibrations problems, as well as good trend agreement between the two surveys, using automatized codes for a big sample. Furthermore, we found that the application of the Mexican Hat Filter for Forced Photometry Light Curves is a good method to compare the variability of objects with multi-epoch spectra and select the most interesting objects to study.

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Title: Understanding the evolution of the isolated galaxy merger triplet in SIT 45 interaction using VLT/MUSE data: Searching for star formation in bridges.

Elgueta Salas Marcos

Marcos Elgueta Salas, María Argudo Fernández, Paulo Vasquez Bustos.

Abstract: The merging system SIT 45 (UGC12589) is an unusual isolated triplet of galaxies and an ideal candidate to investigate processes such as the triggering of star formation due to interaction. The underlying scenario of the formation and evolution of galaxy triplets is still uncertain. We therefore need to study isolated triplets to understand the formation history, evolution and processes during their merger. We will combine VLT/MUSE integral field spectroscopy with high-resolution HSC imaging, exploring whether star formation processes are occurring in the visible bridges of material between galaxies due to their recent interaction. We will estimate the SFR from the H-alpha and H-beta emission and other spectral indices. This will help us to understand what mechanisms must occur in a galaxy interaction in order for star formation to occur in the material bridges.

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Title: Estimating the Accretion Disk Size in the “Einstein Cross” With Chromatic Microlensing

Jerez-Nicurcar, Ramses.

Jerez-Nicurcar. R (Universidad de Valparaíso); Motta. V (Universidad de Valparaíso); Melo. A (Universidad de Valparaíso); Ávila-Vera. F (Universidad de Valparaíso).

Abstract: QSO2237+0307 (z=1,695) is the most studied gravitational lens systems because flux variability is detected. The particularity in this system is QSO images are located in the bulge of a spiral galaxy at z=0,039. Due to this, microlensing is found to analyzing flux ratio among QSO image, and the detection of chromatic microlensing (a wavelength dependency) allow us estimate the size (rs) and temperature profile (p) of the accretion disk, modeling the disk like a gaussian. We use and X-Shooter spectra to measure chromatic microlensing in this system with Lyα, CIV, CIII], MgII, Hβ and Hα emission lines, analyzing flux ratio from the continuum and core emission lines. As preliminary result, we obtained rs and p, which is in agreement with Shakura-Sunyaev thin-disk model.

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Title: The Elephants in the room for the Extragalactic SFRs and M*

Katsianis, Antonios

Katsianis, Antonios - Shanghai Jiao Tong Univesity

Abstract: The “observed” SFR-M* relation of galaxies and the cosmic star formation rate density represent both important canvases for our current knowledge of galaxy formation and are routinely used to constrain cosmological models/simulations. However, a rising number of authors report a severe tension between the SFRs published by different methodologies/groups. In this talk I present some disturbing limitations for both the simulated galaxy SFRs obtained from state-of-the-art cosmological simulations (EAGLE, IllustrisTNG, Simba, Katsianis et al. 2021a, 2021b) and observations (Katsianis et al 2020, 2021b). We employ cosmological simulations combined with radiative transfer and demonstrate that the adopted methodology to obtain galaxy SFRs heavily affects the results of observational studies (Katsianis et al. 2020). Besides observations, simulations are found to suffer from troubling limitations as well (Katsianis et al. 2021). Our findings reflect the need for the employed quenching schemes in state-of-the-art models to be reconsidered. I also discuss briefly the limitations caused by resolution effects and their impact on comparisons with observational studies.

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Title: Use of Convolutional Neural Networks for stellar stream detection

Monsalves González, Nicolás Matías

(1)Monsalves Gonzalez, N., (1)Vera-Casanova, A., (1) Pallero, D.,(1,2)Gómez, F. A., and (1,2)Jaque Arancibia, M.

(1)Departamento de Astronomía, Universidad de La Serena, Avenida Juan Cisternas 1200, La Serena, Chile

(2) Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena, Raúl Bitrán 1305, La Serena, Chile

Abstract: The arrival of large theoretical and observational data sets in the last decade has driven the field towards the development of automated methods to study galaxy formation evolution. Today, thanks to this large amount of data, deep learning models have been successfully applied to a number of different problems, and have been shown to be a viable solution for automation tasks in many scientific fields. In this work we apply deep learning techniques for automated stellar stream detection. Specifically, we use cosmological hydrodynamical simulations of the formation of Milky Way-like galaxies from the state-of-the-art Auriga Project, to generate mock surface brightness maps. These maps, together with different data augmentation approaches, are used to train a convolutional neural network. Different methodologies were then used to test the robustness of the method in both validation and test sets for the same data. Finally, the generalization capability of the network was checked by contrasting the results with independent simulation sets.

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Title: Kinematics of Extreme Emission-Line Galaxies in the Local Universe

Muñoz Vergara, Dania

Muñoz, Dania, Departamento de Astronomía, Universidad de La Serena, Chile

Amorín, Ricardo, Departamento de Astronomía, Universidad de La Serena, Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena, Chile

Firpo, Verónica, Gemini Observatory, NOIRLab, Association of Universities for Research in Astronomy (AURA), Chile

Fernández, Vital, Departamento de Astronomía, Universidad de La Serena, Chile

Bosch, Guillermo, Instituto de Astrofísica de La Plata, CONICET-UNLP, Argentina

Abstract: Extreme Emission-Line Galaxies (EELGs) are compact dwarf oxygen-poor galaxies showing unusually strong optical and UV emission lines and presenting the highest sSFR in the Local Universe. They constitute our best local analogues of primeval galaxies driving reionization in the early Universe. We study their complex gas kinematics, ionization properties, and chemical abundances as a function of their star formation histories and ionizing photon escape, which can be conducted in a level of detail impossible to achieve at high redshifts. In this poster we will present the first results of our recent Gemini GMOS-IFU program aimed at studying the spatially resolved kinematics of the ionized gas in a small sample of EELGs using a detailed multi-Gaussian decomposition.

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Title: APEX observations of H2O in low redshift ULIRGs

Quinatoa, Daysi

Quinatoa, Daysi (Instituto de Física y Astronomía, Universidad de Valparaíso, Chile)

Ibar, Eduardo (Instituto de Física y Astronomía, Universidad de Valparaíso, Chile)

Yang, Chentao(Department of Space, Earth and Environment of the Chalmers University of Technology, Sweden )

Humphreys, Elizabeth(1-European Southern Observatory, Germany. 2- Joint ALMA Observatory, Chile)

Abstract: In this study, we present the detection of the p-H2O(211-202) redshifted water line in IRAS 06035-7102, IRAS 17207-0014, and IRAS 09022-3615, three low redshift ultra-luminous infrared galaxies (ULIRGs) using the Swedish-ESO PI Instrument for APEX (SEPIA) Band-9 mounted at the Atacama pathfinder experiment (APEX). We report flux densities between 0.4 and 1.5 Jy/beam detected over a 5σ significance using approximately 10 hours of integration time per galaxy. These results open an interesting window for studying the interstellar physics of bright and dense z~0.08 ULIRGs.

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Title: BROAD EMISSION-LINE WINGS: IONIZED GAS KINEMATICS OF FIVE LYMAN CONTINUUM EMITTERS

Rodríguez, Matías

Matías Rodríguez (Departamento de Astronomía, Universidad de La Serena), Ricardo Amorín (Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena - Departamento de Astronomía, Universidad de La Serena)

Abstract: Using high dispersion optical spectra from VLT/XShooter we study the ionized gas kinematics of five Lyman continuum emitters at z ~ 0.3 with escape fractions between 3~46 percent. All the galaxies show asymmetric emission-line profiles that can be well reproduced with multiple Gaussian components. A broad component with intrinsic velocity dispersion of ~90-210 km/s is present in all the objects of the sample, which is blue shifted with respect to the global velocity profile, thus suggesting an unresolved outflow. Narrow components with intrinsic velocity dispersion of ~ 40-60 km/s contribute a great percentage of the global flux emissions and trace the prominent HII regions inside the galaxies. Classic diagnostics diagrams show all the components at the limit of excitation by photoionization thus indicating very strong radiation fields. Our results suggest outflows and strong gas turbulence driven by stellar winds and SNe feedback may be responsible for creating channels within a likely clumpy interstellar medium from which LyC photons escape into the intergalactic medium. Finally, we explore relations between the escape fraction of LyC photons and the ionized gas kinematics.

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Title: Analysis Of Morphological Bias In Field Galaxies At 0.2<z<3.0

Salvador, Diego

Diego Salvador, Kimberly Valenzuela

Abstract: The morphological transformations are a key aspect in the evolution of galaxies, as they are related with the changes in their internal dynamics and star formation. Star forming and quiescent galaxies tend to be late-type and early-type, respectively; however, the morphological mixing changes with redshift. Distant star-forming galaxies are mostly irregular, while the fraction of quiescent discs grows with time. Astronomers have traditionally classified galaxies through the visual inspection of their images. Nevertheless, machine learning algorithms are the best solution to perform this task on large survey data. We have embarked in the study of the morphological transformations of galaxies at z=0.2-3.0 in the CANDELS survey with the aim of building a model that describe the evolution of the fractions of the different morphological types. We are classifying galaxies with a deep learning model published in Perez-Carrasco et al. (2019) and quantifying the effects of surface brightness dimming by redshifting nearby galaxies up to z=3 and evaluating the classification model on the simulated images. This poster presents an overview of the project and the results from the ongoing work.

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Title: Search and characterization of AVOCADO dwarf galaxies hosting AGN activity.

Slater, Roy

R. Slater (Universidad de La Serena); R. Amorín (Universidad de La Serena)

Abstract: Quantifying the AGN-host population in nearby dwarf galaxies and studying their properties may provide a key insight into the formation of the first BHs and their connection with the host galaxy evolution. In order to search for robust evidence of AGN activity in low-mass galaxies, we aim at characterizing the emission-line properties of a volume-limited sample of nearby (D~20-60 Mpc) field dwarf galaxies from the Virtual Observatory Census to Address Dwarfs Origins (AVOCADO, Sanchez-Janssen et al. 2013). For this purpose, we apply several AGN selection criteria based on optical spectroscopy and the available multiwavelength photometry, including radio (FIRST), infrared (WISE), optical (SDSS) and X-rays (CHANDRA,XMM-NEWTON). The combination and critical comparison of the different selection criteria allows us to investigate a sample of ~1537 dwarf AGN-candidates, compare their host physical properties with the general dwarf galaxy population in the local universe, and critically discuss caveats related to the several selection criteria in consideration.

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Title: Study of the evolution of isolated mergers using MANGA data

Vasquez Bustos , Paulo Andres

P. Vasquez-Bustos, M.Argudo-Fernandez and M. Boquien

Abstract: Mergers are systems of two or more galaxies that interact causing a deformation in these, we also know that when they interact they will generate star formation processes and AGN activity in specific regions of the system, which can be studied using spatially resolved spectroscopic analysis. The complex interaction scenario is much simpler if it is understood from isolated systems, for this I deal with data from catalogs of isolated galaxies. Using Marvin and CIGALE, an analysis of star formation rate, age, and stellar mass was created to understand whether the state of the interacting galaxies influences the final outcome of the interaction.

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Title: Semi-analytic galaxies on large spatial scales

Vega Martínez, Cristian Antonio

Vega-Martínez, Cristian A. (ULS); Gómez, Facundo A. (ULS); Springel, Volker (MPA)

Abstract: Here we introduce our ongoing research focused on the theoretical study of the formation and evolution of galaxies populating large spatial scales, particularly those in high-density environments. For this, we are developing a consistent model of galaxy formation and evolution based on a semi-analytic approach. This research is part of the MillenniumTNG project. MillenniumTNG arises in the light of the new generation of extremely large galaxy surveys, where new models of galaxy formation that are suitable to predict the properties of galaxy populations observed on spatial scales of multi-Gpc³ are needed.

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Title: Study of AGN properties in central galaxies and satellites from SDSS

Mesa Valeria

V.A. Mesa(1), M.S. Alonso(2), G.V. Coldwell(2), M.F. Duplancic(2), D.G. Lambas(3) y J.L. Nilo Castellón(1),

(1)Departamento de Astronomía, Facultad de Ciencias, Universidad de La Serena - (2)Departamento de Astronomía y Geofísica, CONICET, Facultad de Ciencias Exactas, Físicas y Naturales (FCEFN)--UNSJ -(3) Instituto de Astronomía Teórica y Experimental, CONICET - UNC

Abstract: This poster presents a sample of active galaxy nuclei (AGN) belonging to galaxy systems composed of a central object and two satellites. The sample was obtained from the Sloan Digital Sky Survey (SDSS-DR14) adopting criteria of projected distance ( r p <150 h -1 kpc) and radial velocity difference (ΔV < 500 km/s), restricting satellites at least 1.5 magnitudes fainter than their central galaxy. In addition, an adequate isolation criteria was used to avoid belonging to larger structures. Furthermore, the interaction between the members of each system was classified through a detailed visual inspection. Once the classified sample was obtained, a correlation was carried out with an AGN catalog, selecting those systems where at least one of its members present an active nuclei. We have also considered control samples to analyze the results. The main goal of this study consists of the analysis of the different scenarios in which these systems are found and their influence on the nuclear activity of the galaxies that compose them.

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Title: Extragalactic Fast X-ray Transient Candidates Discovered by Chandra

Quirola-Vasquez, Jonathan

J. Quirola-Vásquez (Pontificia Universidad Católica de Chile); F.E. Bauer (Pontificia Universidad Católica de Chile); P.G. Jonker (Radboud University); W.N. Brandt (The Pennsylvania State University); G. Yang (Texas A&M University,); A.J. Levan (Radboud University); Y.Q. Xue (University of Science and Technology of China); D. Eappachen (Radboud University); X.C. Zheng (Leiden University); B. Luo ( Nanjing University)

Abstract: Extragalactic Fast X-ray Transients (FXRTs) are short flashes of X-ray photons spanning a few seconds to hours, with an uncertain origin. Our ignorance about their physical mechanisms and progenitor systems is due in part to the lack of clear multi-wavelength counterparts in most cases,because they only have been identified serendipitously. We develop a systematic search of FXRTs using a straightforward X-ray flare search algorithm, in the Chandra Source Catalog (Data Release 2.0; 169.6cMs over 592.4 deg2 using only observations with |b|>10º), incorporating various multi-wavelength constraints to rule out Galactic contamination and characterize the candidates. We report the detection of 14 FXRT candidates from a parent sample of 214,701 sources. Candidates have peak 0.5--7 keV fluxes between 1x10-13 to 2x10-10 erg cm-2 s-1 and T90 values from 4 to 48 ks. The sample can be subdivided into two groups: six "nearby" FXRTs that occurred within d<100 Mpc and eight "distant" FXRTs with likely redshifts <0.1. Three distant FXRT candidates exhibit light curves with a plateau (~1-3 ks duration) followed by a power-law decay and X-ray spectral softening, similar to what was observed for the previously reported FXRT CDF-S~XT2. We calculate event rates for the nearby and distant samples of 53.7 and 28.2 deg-2 yr-1, respectively. This novel sample of Chandra-detected extragalactic FXRT candidates, although modest in size, breaks new ground in terms of characterizing the diverse properties, nature, and possible progenitors of these enigmatic events.

Click here to see the full poster (Quirola-Vasquez, Jonathan)