martes 28 de noviembre
SALÓN ROJO (150)
10:20 - 11:00
COFFEE BREAK
11:00 - 12:30
J: Galaxies and Cosmology
Galaxy Surveys
Chair: Camilo Delgado
#226 |
Automatic galaxy detection and measurement in large astronomical photometric surveys
Rodrigo Facundo Haack
1
;
Analía Viviana Smith Castelli
1
;
Claudia Mendes de Oliveira
2
;
Amanda Lopes
1
;
Felipe Almeida Fernandes
3
;
Laerte Sodré Jr.
2
1 - Instituto de Astrofísica de La Plata (CONICET-UNLP).
2 - Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo.
3 - NSF’s NOIRLab, USA.
Resumen:
In this talk I will present the results of my Diploma Thesis and the first steps of my PhD work. Our goal was to detect, in the Southern Photometric Local Universe Survey (S-PLUS) images, galaxies previously reported in the literature as spectroscopically confirmed or probable members of the Fornax Cluster that do not appear or appear excessively deblended in the S-PLUS DR3 and iDR4 catalogs. This happens because the SExtractor input parameters used to obtain the published catalogs are intended to provide useful data for both galactic and extragalactic purposes.
As a main result we obtained catalogs with homogeneous photometry in the direction of the Fornax Cluster. For this purpose we found two sets of parameters suitable to automatically detect and measure different types of astronomical objects: on one hand, faint and/or compact objects close to bright galaxies and, on the other hand, bright and very extended objects. We were able to develop a pipeline that allows us to automate the entire process, works well in other surveys and is ready to be distributed publicly. These catalogs are being used to select targets to observe in the Fornax Cluster region in the framework of the CHANCES project of the 4MOST collaboration.
In the first steps of my PhD work we found that the SExtractor parameters found also work for other directions and distances, for example in the Hydra and Antlia Clusters. Two new sets of parameters were also identified: one capable of avoiding excessive splitting in star-forming galaxies and another that allows us to recover photometry of globular clusters and star-forming knots. We have also applied regression techniques with Machine Learning to solve the problem of missing data (lack of information in some filter) in the catalogs, and from this, perform template-fitting for each of the sources using LEPHARE.
#167 |
The 4MOST spectroscopic survey facility and the CHileAN Cluster galaxy Evolution Survey (CHANCES)
Christopher Haines
1
1 - Universidad de Atacama.
Resumen:
4MOST is ESO’s flagship spectroscopic survey facility that will be installed on the 4m VISTA telescope at Cerro Paranal next year. It is a fibre-fed spectrograph able to simultaneously obtain high-resolution spectra for 2400 objects over a field of view of 4.2 square degrees. It will carry out 18 public spectroscopic surveys that are expected to deliver spectra for 25 million objects across the entire Southern hemisphere over the first 5 years of operations from October 2024. We present the CHileAN Cluster galaxy Evolution Survey (CHANCES), one of the public surveys to be carried out with 4MOST. CHANCES will target 300,000 galaxies in and around 150 of the most massive galaxy clusters in the local Universe and out to z=0.45. We will target galaxies out to 5r200 from each cluster, enabling us to map the surrounding filamentary large-scale structures and identify the infalling X-ray groups that mark the key sites for pre-processing of galaxies prior to their arrival into the clusters. A second science focus will be the evolution of the cluster dwarf population in nearby clusters where we will push to stellar masses of 10$^9$ M$_{\odot}$ and below. Such low-mass galaxies outside of clusters are naturally gas-rich and will form the bulk of detections in ongoing and upcoming HI surveys from MeerKAT, ASKAP and SKA. The impact of cluster and group environments on the HI gas contents of low-mass galaxies is a key science objective of these HI surveys and should provide natural synergies with CHANCES.
#440 |
The Next Generation Fornax Survey (NGFS)
Thomas H. Puzia
1
;
Yasna Ordenes-Briceño
1
;
Paul Eigenthaler
1
;
Matías Blaña
1
;
Bryan Miller
2
;
Prasanta Nayak
1
;
Rohan Rahatgaonkar
1
;
Tuila Ziliotto
3
;
Mareclo Mora
4
;
Alejandra Hernandez
5
;
Evelyn Johnston
6
1 - Pontificia Universidad Católica de Chile.
2 - Gemini Obseratory/NSF’s NOIRLab.
3 - Università degli studi di Padova.
4 - Las Campanas Observatory.
5 - Universidad de Atacama.
6 - Universidad Diego Portales.
Resumen:
The Next Generation Fornax Survey (NGFS) targets all baryonic structures down to GC masses within the virial sphere of the Fornax galaxy cluster, utilizing the optical bands $u', g'$, and $i'$ in conjunction with the near-infrared (NIR) $J$ and $K_s$ filters. The NGFS uses an intricate observing technique to reach deep surface brightness limits that allows us to detect ultra-low surface brightness dwarf galaxies. Using the observing efficiency of DECam on the Blanco telescope at CTIO, complemented by NIR observations from VIRCAM on the VISTA telescope at ESO, we have secured large enough samples of galaxies to conduct volume-limited studies of their scaling relations. In this talk, I will present exciting new results based on the H-alpha extension of NGFS, showing intriguing recent star-formation activity in galaxies. Furthermore, I will showcase our most recent findings related to the dynamical properties of satellite galaxies within the Fornax galaxy cluster. Our analysis has identified a distinct transition radius, demarcating two zones where satellites exhibit varying properties of tidal stress. Intriguingly, this substructure mirrors patterns observed in cosmological galaxy simulations. Furthermore, when examining diverse cosmic environments, we discern a comparable transition radius in the Virgo galaxy cluster, as well as among the satellite galaxies of both the Milky Way and Andromeda. Finally, I will also discuss NGFS in the context with our other ongoing projects such as the Neighborhood Watch survey, which targets lower-density environments in the local universe.
#563 |
Morphological characterization of the MaNGA galaxies
Jose Antonio Vazquez-Mata
1
;
Hector Hernandez
1
;
Vladimir Avila
1
;
Aldo Rodriguez
1
;
Ivan Lacerna
2
1 - UNAM.
2 - Universidad de Atacama.
Resumen:
Galaxy morphology summarises the internal and external physical processes that lead to the present shapes of galaxies. A reliable morphological classification is therefore essential for analysing and interpreting the physical properties of galaxies.
In this presentation, I will discuss the recent Visual Morphology Catalogue (a SDSS-VAC) for the whole MaNGA galaxies. This catalogue introduces an innovative method for morphologically classifying galaxies across the complete Hubble sequence with high accuracy. It enables us to identify not only bars, but also faint tidal streams surrounding galaxies. We also estimated the structural parameters, concentration, asymmetry and clumpiness. This classification, identification and estimation is based on deep images from the DESI Legacy Surveys, coupled with meticulous image processing techniques.
We have correlated these findings with galaxy properties such as stellar mass, colours and stellar populations age. This has revealed distinct correlations between bars, tidal streams, and both morphology and stellar mass. Through the galaxy stellar mass function, we have investigated the contribution of each individual morphological type within specific stellar mass ranges. This exploration has unveiled the contribution by each type across different mass thresholds. For instance, Elliptical galaxies exclusively dominate the high mass end, with a non- influence extending to stellar masses below $logM_{\ast}$=10. Conversely, very late galaxies govern the low mass domain. Finally we present results that establish comprehensive connections between all reliably morphological types and the group environmental context (galaxies are divided into central or satellites).
#344 |
Characterizing Halpha emission in the Fornax cluster with S-PLUS
Amanda Lopes
1
;
Analía Smith-Castelli
1
;
Eduardo Telles
2
1 - Instituto de Astrofísica de La Plata.
2 - Observatório Nacional (ON/MCTI).
Resumen:
Emission lines in galaxies are a valuable source of information, allowing the study of star formation activity, the identification of active galactic nuclei, among others. The filter configuration of S-PLUS (Southern Photometric Local Universe Survey) is ideal to detect emission by its combination of 7 narrow and 5 broad optical passband filters. An interesting topic to investigate is the characteristics of the emitters in high density environments. Do they present a specific location within the cluster? How is the relation between the emission morphology and the galaxy morphology? The answer to such questions can give us clues about the formation of a given cluster. In this context, the Fornax cluster is a great target to be analyzed, as the Halpha+[NII] emission lines are located within the J0660 band of S-PLUS, and its proximity provides large enough galaxies to study their emission spatial distribution. In this talk we will present our code (P.E.L.E., Pixel-to-pixel Emission Line Estimate) to create Halpha+[NII] maps based on the three filter method applied to S-PLUS images, and our main results derived for 213 Fornax galaxy members, including the spatial distribution and the phase-space diagram of Halpha emitters, the relation between Halpha emission and the galaxy Sersic index, and the comparison between P.E.L.E. maps and the results from Fornax 3D project.
#025 |
The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc
Ingrid Vanessa Daza Perilla
1
;
Mario Sgró
1
;
Laura Baravalle
1
;
María Alonso
1
;
Carolina Villalon
1
;
Marcelo Lares
1
;
Mario Soto
1
;
Jose Nilo
2
;
Carlos Valotto
1
;
Pamela Cortés
2
;
Dante Minniti
3
;
Maren Hempel
4
1 - Instituto de Astronomía Teórica y Experimental.
2 - Facultad de Ciencias, Physics and astronomy.
3 - Departamento de Fisica, Universidade Federal de Santa Catarina.
4 - Instituto de Astrofisica - Facultad de Ciencias Exactas - Universidad Andres Bello.
Resumen:
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.
12:30 - 14:30
LUNCH
16:20 - 17:00
COFFEE BREAK
17:00 - 18:15
J: Galaxies and Cosmology
Gravitational lensing
Chair: Eduardo Cypriano
#228 |
Cosmological applications of newly discovered gravitational lensed quasars
Verónica Motta
1
1 - Universidad de Valparaíso.
Resumen:
Strong lensing is a useful technique for examining astrophysical issues such as the general content and kinematics of the Universe as well as the study of distant active galactic nuclei (AGN) that are too small to be resolved with current telescopes. As variable sources, AGNs enable measurements of the time delays between images, which can be used to measure absolute distances (i.e., an alternative technique to constrain the Hubble constant). Microlensing (the brightness variations caused by stars as they move in front of each quasar image) of the compact source can be used to probe the mass at compact scales in the lens galaxy (Initial Mass Function) as well as the innermost structure of the source (accretion disk structure).
AGNs are often lensed into two images; four images (quads) are less frequent. For cosmology studies, such as measuring the distance to objects, quads are preferable because their modeling is more precise. In contrast to the 15 previously known quads, in recent years our collaboration has discovered 30 additional quads for which I will present some results of those astrophysical applications.
#093 |
Parametric Strong-Lensing Analysis of a High-Disturbance Galaxy Cluster
Carla Cornil-Baïotto
1
1 - Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile.
Resumen:
Galaxy clusters, as the largest gravitationally bound systems in the Universe, are an important laboratory for studying dark matter. In the inner core of rich galaxy clusters, gravity can create remarkable visual mirages through the significant bending of light by high mass concentrations, the so-called strong gravitational lensing phenomenon. Strong lens modeling plays a key role in mapping the mass distribution of galaxy clusters, providing insights into the spatial distribution of dark matter and its role in cluster evolution. In this short talk, I will present the results of the parametric strong lensing analysis of a highly disturbed galaxy cluster. Firstly, I will detail the approach to model the mass distribution of its core that hosts a giant arc and multiple images of distant galaxies in the optical, using the software Lenstool. Then, I will introduce the cluster’s multi-wavelength analysis, taking advantage of HST, DES, MUSE, MeerKAT, and XMM-Newton observations. This extensive multi-wavelength analysis allowed us to understand the effects of the environment turbulence on the high ellipticity of the cluster’s central dark matter halo, and recover the tumultuous evolutionary history of this galaxy cluster (Cornil-Baïotto et al., in prep).
#191 |
Microlensing scale estimation for 190 lensed quasars
Felipe Avila Vera
1
;
Verónica Motta
1
1 - Universidad de Valparaíso.
Resumen:
Gravitationally lensed quasars (QSO) have multiple applications in cosmology and to study the structure of the quasar. One of the problems for the modeling is that the image fluxes could be affected by microlensing produced by stars in the lens galaxy. Recently, TDCosmo has almost doubled the known systems with respect to the previous decade. We present, for the first time, the automatic modeling of 190 systems to obtain a homogeneous sample, and reduce systematic errors in lens parameters. These models are used to estimate the microlensing timescales, i.e. the timescale in which the source (QSO) crosses the Einstein radius of the microlens (star), which also introduces variation in the QSO image fluxes. We found median Einstein radius crossing time scales of 22.17 years, and median source crossing time scale of 8.5 months. This means that in $\sim$ 10 years, part of the sources will be on the caustics (affected by microlensing), and the other part will be quiescent
#104 |
Uniform modeling of 21 strong lensing systems in ground-based surveys: Follow-up observations and constraints on modified gravity
João Paulo Correia de França
1
;
Martin Makler
2
;
Renan Oliveira
3
;
James Nightingale
4
;
Ingrid Beloto
5
;
Eduardo Cypriano
5
1 - CBPF.
2 - CBPF, ICAS, ICIF, UNSAM.
3 - UFES.
4 - Durham University.
5 - IAG USP.
Resumen:
Gravitational arcs are strongly magnified images of distant galaxies (known as sources) caused by the deflection of light produced by a foreground galaxy or galaxy cluster (the lens). The modeling of gravitational lenses has been used to study high-redshift sources, to assess the mass distribution in the lens, to constrain cosmological parameters and to set limits on modified gravity. In particular, with the next generation wide-field imaging surveys, such as Euclid and Rubin (LSST), we expect to discover on the order of $10^4$ such systems, which will require efficient and automated modeling methods to explore their applications. In this work, we present a (semi-)automated modeling pipeline which iteratively derives the PSF from the images, masks nearby non-lensed sources and simultaneously derives the lens model parameters and the source light in a non-regular Voronoi grid in multiwavelength data. With this pipeline we were able to model uniformly a sample of 21 gravitational lenses in ground-based surveys including the Hyper Suprime Cam (HSC) SuGOHI sample, the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS) and the Legacy Survey. Additionally, we carried out spectroscopic follow-up observations on the SOuthern Astrophysical Research (SOAR) telescope specially aiming to measure the lens velocity dispersions. We combine the results from the SOAR data with our lens modeling to derive constraints on the post-Newtonian parameter $\eta_{PPN}$. There are the first constraints on $\eta_{PPN}$ purely from ground-based data and with a totally independent sample from other studies in the literature. These results pave the way to study the constraints on $\eta_{PPN}$ that could be derived from LSST data.
#582 |
Accretion disk parameters estimations in The Einstein Cross using X-shooter (VLT) spectra and multiple epochs photometry data.
Ramses Jerez-Nicurcar
1
;
Veronica Motta
1
1 - Universidad de Valparaiso.
Resumen:
Until today, there have been nearly 220 gravitational lens systems discovered and confirmed with different methods and techniques, and only a fraction of them have been able to estimate the size of their internal structure (i.e., accretion disk, broad emission line region).
In my Master’s thesis we studied the gravitationallens systems QSO2237+0305 (The Einstein’s Cross) which show four quasar images. This lens system is peculiar because the lensing galaxy is very close ( zl = 0.04 and Zs=1.69).
We examined the emission lines and the continuum emission below them using the spectra of each lensed image and also questioned the existence of extinction in the core of the emission lines.
We confirmed the existence of microlensing effect in the continuum spectra of the quasar images and also with the photometric observation. Besides, we have observed a wavelength dependency in this effect, which means in the detection of the chromatic microlensing effect. This enables us to model the accretion disk with a temperature profile p and a size r, with a power law relating the two parameters: r $\propto$ $\lambda^{p}$. Our measurements of the accretion disk parameters were compared with the previous estimations in the literature, which are in good agreement.
