Astrofísica

We revisit the Quasar Main Sequence (QMS) by investigating the impact of the stellar component from the host galaxy (HG) on the emission-line spectra of active galactic nuclei (AGN). After identifying SDSS-DR19 type 1 AGN spectra, we constructed the Index diagram, a novel, model-independent diagnostic based on redshift-corrected spectra, designed to efficiently identify sources with significant stellar HG contributions and to classify AGN spectra into three categories: HG-dominated (HGD), intermediate (INT), and AGN-dominated (AGND) sources. Our QMS analysis shows that HGD sources predominantly occupy the Population B region, typically exhibiting negligible FeII emission, while INT and AGND sources display similar distributions in the Population A region. Cross-matching with radio, infrared, and X-ray catalogues reveals that the strongest radio emitters are preferentially associated with HGD and INT sources, whereas strong X-ray emitters are found among INT and AGND objects, which also populate the AGN region in the WISE colour diagram. The applicability of the Index diagram is also demonstrated by its implementation in large spectroscopic datasets, including SDSS DR20 and DESI, enabling systematic studies of AGN-HG decomposition across big data samples.

Upcoming imaging surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will provide high-precision clustering measurements, requiring robust methods to connect galaxies with their dark matter haloes. In the first part of this talk, I will present a method to estimate halo occupation distributions directly from photometric data, adapted for LSST-like observations and tested using the CosmoDC2 mock galaxy catalog. In the second part, I will discuss the origin of extremely compact massive galaxies observed at high redshift by the James Webb Space Telescope. Using the high-resolution FirstLight simulations, we show that galaxies undergo a cycle of expansion, compaction, and re-expansion driven by gas inflows that trigger intense central star formation. This process can naturally produce the very small galaxy sizes observed at $z\gtrsim6$ and suggests the presence of a universal wet-compaction phase during cosmic dawn.

The Revista Mexicana de Astronomía y Astrofísica (RMxAA) has established itself throughout its history as one of the most important scientific journals in Latin America. In 2024, coinciding with its 50th anniversary, the RMxAA launched a renewal process. This talk presents a historical overview and updates regarding the Editorial Board of RMxAA and the Conference Series (RMxAC). We present the renewed Scientific Editorial Committee and a new website platform on the Open Journal System, which now allows for a more expedited editorial process and offers users a more modern and user-friendly system. We also introduced new LaTeX template macros for articles in RMxAA and RMxAC. We increased the RMxAA publication frequency, and implemented important innovations. Publishing in RMxAA has always been and will continue to be free of charge and open access, with a global outlook. We are committed to maintaining, and if possible, further increasing the publication frequency, upholding strict peer review with highly qualified reviewers, and actively promoting the journal at astronomical research institutions worldwide. We aim to raise its impact metrics alongside the most highly regarded peer-reviewed journals in the field. As the Editorial Board, we are convinced that in coordination with institutions conducting astronomical research in Latin America and other parts of the world, we can lead the RMxAA to a high-quality model that could counteract the current predatory model for publishing in the physical sciences.

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I will present preliminary results from a study of multiwavelength light curves for targets from the Nearby Evolved Stars Survey (NESS; Scicluna et al. 2022). NESS is investigating ∼800 asymptotic giant branch (AGB) and red supergiant (RSG) stars within ≲5 kpc to understand the mass-loss process and its connection to circumstellar gas and dust. These nearby evolved stars are long-period variables with photometric monitoring across many all-sky surveys and wavelengths. To connect photospheric variability with circumstellar emission, we compiled more than 5000 light curves for over 700 NESS targets using over 20 optical, near-infrared, and mid-infrared filters. To fit these light curves and derive their periods, we use the Python Gaussian Processes for MUltiwavelength Variability Inference (PGMUVI; Scicluna et al., subm.) code. Our results, when combined with existing information from the literature as well as NESS results, allow us to revisit correlations between variability properties and parameters such as mass-loss rate, providing robust constraints on evolved stars in the Solar Neighbourhood. Previous studies have generally focused on either smaller samples or narrower wavelength coverage. The PGMUVI framework enables multiwavelength extension of such studies in a consistent fashion, allowing for a robust determination of variability properties. I will demonstrate this by comparing our results for the long-secondary period (LSP) phenomenon observed in many long-period variable stars. A small fraction (∼5%) of AGB stars dominates (>75%) the dust production in nearby galaxies. The dustiest sources are often detectable only at near- and mid-infrared wavelengths and, without mid-infrared spectroscopy, can be difficult to distinguish from young stellar objects. An important application of this work is the use of mid-infrared variability to identify extreme carbon stars and possible massive AGB or super-AGB candidates in nearby galaxies.

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