المؤلفون: Sánchez-Sáez, P., Hernández-García, L., Bernal, S., Bayo, A., Rivera, G. Calistro, Bauer, F. E., Ricci, C., Merloni, A., Graham, M. J., Cartier, R., Arévalo, P., Assef, R. J., Concas, A., Homan, D., Krumpe, M., Lira, P., Malyali, A., Martínez-Aldama, M. L., Arancibia, A. M. Muñoz, Rau, A., Bruni, G., Förster, F., Pavez-Herrera, M., Tubín-Arenas, D., Brightman, M.

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena

الوصف: The galaxy SDSS1335+0728, which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). Its behaviour suggests that SDSS1335+0728 hosts a $\sim 10^6 M_{\odot}$ black hole (BH) that is currently in the process of `turning on'. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. We used archival photometry and spectroscopic data to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We find that: (a) since 2021, the UV flux is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1-W2 WISE colour has become redder; (c) since February 2024, the source has begun showing X-ray emission; (d) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (e) broad emission lines are not detected; and (f) the [OIII] line increased its flux $\sim 3.6$ years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. We conclude that the variations observed in SDSS1335+0728 could be either explained by an AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGN observed in the process of activating. If the latter, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour.
Comment: Accepted for publication in Astronomy & Astrophysics. ESO press release available at https://www.eso.org/public/news/eso2409Test/. Abstract shortened for arXiv

الوصول الحر: http://arxiv.org/abs/2406.11983Test

المؤلفون: Cabrera-Vives, G., Moreno-Cartagena, D., Astorga, N., Reyes-Jainaga, I., Förster, F., Huijse, P., Arredondo, J., Arancibia, A. M. Muñoz, Bayo, A., Catelan, M., Estévez, P. A., Sánchez-Sáez, P., Álvarez, A., Castellanos, P., Gallardo, P., Moya, A., Rodriguez-Mancini, D.

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: The advent of next-generation survey instruments, such as the Vera C. Rubin Observatory and its Legacy Survey of Space and Time (LSST), is opening a window for new research in time-domain astronomy. The Extended LSST Astronomical Time-Series Classification Challenge (ELAsTiCC) was created to test the capacity of brokers to deal with a simulated LSST stream. We describe ATAT, the Astronomical Transformer for time series And Tabular data, a classification model conceived by the ALeRCE alert broker to classify light-curves from next-generation alert streams. ATAT was tested in production during the first round of the ELAsTiCC campaigns. ATAT consists of two Transformer models that encode light curves and features using novel time modulation and quantile feature tokenizer mechanisms, respectively. ATAT was trained on different combinations of light curves, metadata, and features calculated over the light curves. We compare ATAT against the current ALeRCE classifier, a Balanced Hierarchical Random Forest (BHRF) trained on human-engineered features derived from light curves and metadata. When trained on light curves and metadata, ATAT achieves a macro F1-score of 82.9 +- 0.4 in 20 classes, outperforming the BHRF model trained on 429 features, which achieves a macro F1-score of 79.4 +- 0.1. The use of Transformer multimodal architectures, combining light curves and tabular data, opens new possibilities for classifying alerts from a new generation of large etendue telescopes, such as the Vera C. Rubin Observatory, in real-world brokering scenarios.

الوصول الحر: http://arxiv.org/abs/2405.03078Test

المؤلفون: Silva-Farfán, Javier, Förster, Francisco, Moriya, Takashi J., Hernández-García, L., Arancibia, A. M. Muñoz, Sánchez-Sáez, P., Anderson, Joseph P., Tonry, John L., Clocchiatti, Alejandro

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We report an analysis of a sample of 186 spectroscopically confirmed Type II supernova (SN) light curves (LCs) obtained from a combination of Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System (ATLAS) observations. We implement a method to infer physical parameters from these LCs using hydrodynamic models that take into account the progenitor mass, the explosion energy, and the presence of circumstellar matter (CSM). The CSM is modelled via the mass loss rate, wind acceleration at the surface of the progenitor star with a $\beta$ velocity law, and the CSM radius. We also infer the time of explosion, attenuation (A$_V$), and the redshift for each SN. Our results favor low-mass progenitor stars (M$_{ZAMS}$\,$<$14\,$M_\odot$) with a dense CSM ($\dot{M}$ $>$ 10$^{-3}$ [M$_\odot$ yr$^{-1}$], a CSM radius of $\sim$ 10$^{15}$ cm, and $\beta$ $>$ 2). Additionally, we find that the redshift inferred from the supernova LCs is significantly more accurate than that inferred using the host galaxy photometric redshift, suggesting that this method could be used to infer more accurate host galaxy redshifts from large samples of SNe II in the LSST era. Lastly, we compare our results with similar works from the literature.

الوصول الحر: http://arxiv.org/abs/2404.12620Test

المؤلفون: Guerrero, Andrea, Nagar, Neil, Kohno, Kotaro, Fujimoto, Seiji, Kokorev, Vasily, Brammer, Gabriel, Jolly, Jean-Baptiste, Knudsen, Kirsten, Sun, Fengwu, Bauer, Franz E., Caminha, Gabriel B., Caputi, Karina, Neumann, Gerald, Orellana-González, Gustavo, Cerulo, Pierluigi, González-López, Jorge, Laporte, Nicolas, Koekemoer, Anton M., Ao, Yiping, Espada, Daniel, Arancibia, Alejandra M. Muñoz

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: We develop new tools for continuum and spectral stacking of ALMA data, and apply these to the ALMA Lensing Cluster Survey (ALCS). We derive average dust masses, gas masses and star formation rates (SFR) from the stacked observed 260~GHz continuum of 3402 individually undetected star-forming galaxies, of which 1450 are cluster galaxies and 1952 field galaxies, over three redshift and stellar mass bins (over $z = 0$-1.6 and log $M_{*} [M_{\odot}] = 8$-11.7), and derive the average molecular gas content by stacking the emission line spectra in a SFR-selected subsample. The average SFRs and specific SFRs of both cluster and field galaxies are lower than those expected for Main Sequence (MS) star-forming galaxies, and only galaxies with stellar mass of log $M_{*} [M_{\odot}] = 9.35$-10.6 show dust and gas fractions comparable to those in the MS. The ALMA-traced average `highly obscured' SFRs are typically lower than the SFRs observed from optical to near-IR spectral analysis. Cluster and field galaxies show similar trends in their contents of dust and gas, even when field galaxies were brighter in the stacked maps. From spectral stacking we find a potential CO ($J=4\to3$) line emission (SNR $\sim4$) when stacking cluster and field galaxies with the highest SFRs.
Comment: 13 pages, 8 figures, 1 table (+4 pages, 4 figures in Appendix). Accepted for publication in MNRAS

الوصول الحر: http://arxiv.org/abs/2309.16832Test

المؤلفون: Cabrera-Vives, Guillermo, Bolivar, César, Förster, Francisco, Arancibia, Alejandra M. Muñoz, Pérez-Carrasco, Manuel, Reyes, Esteban

المصدر: ICML 2023 Workshop on Machine Learning for Astrophysics

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Computer Science - Artificial Intelligence, Computer Science - Machine Learning, I.2.1

الوصف: Time domain astronomy is advancing towards the analysis of multiple massive datasets in real time, prompting the development of multi-stream machine learning models. In this work, we study Domain Adaptation (DA) for real/bogus classification of astronomical alerts using four different datasets: HiTS, DES, ATLAS, and ZTF. We study the domain shift between these datasets, and improve a naive deep learning classification model by using a fine tuning approach and semi-supervised deep DA via Minimax Entropy (MME). We compare the balanced accuracy of these models for different source-target scenarios. We find that both the fine tuning and MME models improve significantly the base model with as few as one labeled item per class coming from the target dataset, but that the MME does not compromise its performance on the source dataset.

الوصول الحر: http://arxiv.org/abs/2308.07538Test

المؤلفون: Kohno, K., Fujimoto, S., Tsujita, A., Kokorev, V., Brammer, G., Magdis, G. E., Valentino, F., Laporte, N., Sun, Fengwu, Egami, E., Bauer, F. E., Guerrero, A., Nagar, N., Caputi, K. I., Caminha, G. B., Jolly, J. -B., Knudsen, K. K., Uematsu, R., Ueda, Y., Oguri, M., Zitrin, A., Ouchi, M., Ono, Y., Gonzalez-Lopez, J., Richard, J., Smail, I., Coe, D., Postman, M., Bradley, L., Koekemoer, A. M., Arancibia, A. M. Munoz, Dessauges-Zavadsky, M., Espada, D., Umehata, H., Hatsukade, B., Egusa, F., Shimasaku, K., Matsui-Morokuma, K., Wang, W. -H., Wang, T., Ao, Y., Baker, A. J., Lee, Minju M., Lagos, C. del P., Hughes, D. H., collaboration, ALCS

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: The ALMA lensing cluster survey (ALCS) is a 96-hr large program dedicated to uncovering and characterizing intrinsically faint continuum sources and line emitters with the assistance of gravitational lensing. All 33 cluster fields were selected from HST/Spitzer treasury programs including CLASH, Hubble Frontier Fields, and RELICS, which also have Herschel and Chandra coverages. The total sky area surveyed reaches $\sim$133 arcmin$^2$ down to a depth of $\sim$60 $\mu$Jy beam$^{-1}$ (1$\sigma$) at 1.2 mm, yielding 141 secure blind detections of continuum sources and additional 39 sources aided by priors. We present scientific motivation, survey design, the status of spectroscopy follow-up observations, and number counts down to $\sim$7 $\mu$Jy. Synergies with JWST are also discussed.
Comment: 6 pages, 4 figures, Proceedings of the 7th Chile-Cologne-Bonn-Symposium: Physics and Chemistry of Star Formation, V. Ossenkopf-Okada, R. Schaaf, I. Breloy (eds.)

الوصول الحر: http://arxiv.org/abs/2305.15126Test

المؤلفون: Reyes-Jainaga, Ignacio, Förster, Francisco, Arancibia, Alejandra M. Muñoz, Cabrera-Vives, Guillermo, Bayo, Amelia, Bauer, Franz E., Arredondo, Javier, Reyes, Esteban, Pignata, Giuliano, Mourão, A. M., Silva-Farfán, Javier, Galbany, Lluís, Álvarez, Alex, Astorga, Nicolás, Castellanos, Pablo, Gallardo, Pedro, Moya, Alberto, Rodríguez, Diego

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: In recent years, automatic classifiers of image cutouts (also called "stamps") have shown to be key for fast supernova discovery. The Vera C. Rubin Observatory will distribute about ten million alerts with their respective stamps each night, enabling the discovery of approximately one million supernovae each year. A growing source of confusion for these classifiers is the presence of satellite glints, sequences of point-like sources produced by rotating satellites or debris. The currently planned Rubin stamps will have a size smaller than the typical separation between these point sources. Thus, a larger field of view stamp could enable the automatic identification of these sources. However, the distribution of larger stamps would be limited by network bandwidth restrictions. We evaluate the impact of using image stamps of different angular sizes and resolutions for the fast classification of events (AGNs, asteroids, bogus, satellites, SNe, and variable stars), using data from the Zwicky Transient Facility. We compare four scenarios: three with the same number of pixels (small field of view with high resolution, large field of view with low resolution, and a multi-scale proposal) and a scenario with the full stamp that has a larger field of view and higher resolution. Compared to small field of view stamps, our multi-scale strategy reduces misclassifications of satellites as asteroids or supernovae, performing on par with high-resolution stamps that are 15 times heavier. We encourage Rubin and its Science Collaborations to consider the benefits of implementing multi-scale stamps as a possible update to the alert specification.
Comment: Accepted for publication in ApJL

الوصول الحر: http://arxiv.org/abs/2304.13080Test

المؤلفون: Sánchez-Sáez, P., Arredondo, J., Bayo, A., Arévalo, P., Bauer, F. E., Cabrera-Vives, G., Catelan, M., Coppi, P., Estévez, P. A., Förster, F., Hernández-García, L., Huijse, P., Kurtev, R., Lira, P., Arancibia, A. M. Muñoz, Pignata, G.

المصدر: A&A 675, A195 (2023)

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Astrophysics of Galaxies

الوصف: We present a variability, color and morphology based classifier, designed to identify transients, persistently variable, and non-variable sources, from the Zwicky Transient Facility (ZTF) Data Release 11 (DR11) light curves of extended and point sources. The main motivation to develop this model was to identify active galactic nuclei (AGN) at different redshift ranges to be observed by the 4MOST ChANGES project. Still, it serves as a more general time-domain astronomy study. The model uses nine colors computed from CatWISE and PS1, a morphology score from PS1, and 61 single-band variability features computed from the ZTF DR11 g and r light curves. We trained two versions of the model, one for each ZTF band. We used a hierarchical local classifier per parent node approach, where each node was composed of a balanced random forest model. We adopted a 17-class taxonomy, including non-variable stars and galaxies, three transient classes, five classes of stochastic variables, and seven classes of periodic variables. The macro averaged precision, recall and F1-score are 0.61, 0.75, and 0.62 for the g-band model, and 0.60, 0.74, and 0.61, for the r-band model. When grouping the four AGN classes into one single class, its precision, recall, and F1-score are 1.00, 0.95, and 0.97, respectively, for both the g and r bands. We applied the model to all the sources in the ZTF/4MOST overlapping sky, avoiding ZTF fields covering the Galactic bulge, including 86,576,577 light curves in the g-band and 140,409,824 in the r-band. Only 0.73\% of the g-band light curves and 2.62\% of the r-band light curves were classified as stochastic, periodic, or transient with high probability ($P_{init}\geq0.9$). We found that, in general, more reliable results are obtained when using the g-band model. Using the latter, we identified 384,242 AGN candidates, 287,156 of which have $P_{init}\geq0.9$.
Comment: Accepted for publication in Astronomy & Astrophysics. Abstract shortened for arXiv. Tables containing the classifications and features for the ZTF g and r bands, and the labeled sets will be available at CDS. Individual catalogs per class and band, as well as the labeled set catalogs, can be downloaded at Zenodo DOI:10.5281/zenodo.7826045

الوصول الحر: http://arxiv.org/abs/2304.08519Test

المؤلفون: Hernández-García, L., Panessa, F., Bruni, G., Bassani, L., Arévalo, P., Patiño-Alvarez, V. M., Tramacere, A., Lira, P., Sánchez-Sáez, P., Bauer, F. E., Chavushyan, V., Carraro, R., Förster, F., Arancibia, A. M. Muñoz, Ubertini, P.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies

الوصف: PBC J2333.9-2343 is a giant radio galaxy at z = 0.047 with a bright central core associated to a blazar nucleus. If the nuclear blazar jet is a new phase of the jet activity, then the small orientation angle suggest a dramatic change of the jet direction. We present observations obtained between September 2018 and January 2019 (cadence larger than three days) with Effeslberg, SMARTS-1.3m, ZTF, ATLAS, Swift, and Fermi-LAT, and between April-July 2019 (daily cadence) with SMARTS-1.3m and ATLAS. Large (>2x) flux increases are observed on timescales shorter than a month, which are interpreted as flaring events. The cross correlation between the SMARTS-1.3m monitoring in the NIR and optical shows that these data do not show significant time lag within the measured errors. A comparison of the optical variability properties between non-blazars and blazars AGN shows that PBC J2333.9-2343 has properties more comparable to the latter. The SED of the nucleus shows two peaks, that were fitted with a one zone leptonic model. Our data and modelling shows that the high energy peak is dominated by External Compton from the dusty torus with mild contribution from Inverse Compton from the jet. The derived jet angle of 3 degrees is also typical of a blazar. Therefore, we confirm the presence of a blazar-like core in the center of this giant radio galaxy, likely a Flat Spectrum Radio Quasar with peculiar properties.
Comment: Accepted for publication in MNRAS. 15 pages, 6 figures, 2 appendix including tables and figures

الوصول الحر: http://arxiv.org/abs/2303.08842Test

المؤلفون: Fujimoto, Seiji, Kohno, Kotaro, Ouchi, Masami, Oguri, Masamune, Kokorev, Vasily, Brammer, Gabriel, Sun, Fengwu, Gonzalez-Lopez, Jorge, Bauer, Franz E., Caminha, Gabriel B., Hatsukade, Bunyo, Richard, Johan, Smail, Ian, Tsujita, Akiyoshi, Ueda, Yoshihiro, Uematsu, Ryosuke, Zitrin, Adi, Coe, Dan, Kneib, Jean-Paul, Postman, Marc, Umetsu, Keiichi, Lagos, Claudia del P., Popping, Gergo, Ao, Yiping, Bradley, Larry, Caputi, Karina, Dessauges-Zavadsky, Miroslava, Egami, Eiichi, Espada, Daniel, Ivison, R. J., Jauzac, Mathilde, Knudsen, Kirsten K., Koekemoer, Anton M., Magdis, Georgios E., Mahler, Guillaume, Arancibia, A. M. Munoz, Rawle, Timothy, Shimasaku, Kazuhiro, Toft, Sune, Umehata, Hideki, Valentino, Francesco, Wang, Tao, Wang, Wei-Halo

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics

الوصف: We present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the ALMA Lensing Cluster Survey (ALCS) over a total of 133 arcmin$^{2}$ area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint mm sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing {\it Hubble Space Telescope} and {\it Spitzer} images. The dust continuum sources belong to a blind sample ($N=141$) with S/N $\gtrsim$ 5.0 (a purity of $>$ 0.99) or a secondary sample ($N=39$) with S/N= $4.0-5.0$ screened by priors. With the blind sample, we securely derive 1.2-mm number counts down to $\sim7$ $\mu$Jy, and find that the total integrated 1.2mm flux is 20.7$^{+8.5}_{-6.5}$ Jy deg$^{-2}$, resolving $\simeq$ 80 % of the cosmic infrared background light. The resolved fraction varies by a factor of $0.6-1.1$ due to the completeness correction depending on the spatial size of the mm emission. We also derive infrared (IR) luminosity functions (LFs) at $z=0.6-7.5$ with the $1/V_{\rm max}$ method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (=UV+IR) cosmic star-formation rate density (SFRD) at $z>4$ is estimated to be $161^{+25}_{-21}$ % of the established measurements, which were almost exclusively based on optical$-$NIR surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional ($\approx 60$ %) SFRD component contributed by the faint-mm population, including NIR dark objects.
Comment: ApJS in press, 34 pages, 8 Tables, and 18 Figures (+38 pages, 5 Tables, and 6 Figures in Appendix)

الوصول الحر: http://arxiv.org/abs/2303.01658Test