Probing the Sub-Parsec Dust of a Supermassive Black Hole with the Tidal Disruption Event AT 2020mot

AT 2020mot is a typical UV/optical tidal disruption event (TDE) with no radio or X-ray signatures in a quiescent host. We find an i-band excess and re-brightening along the decline of the light curve which could be due to two consecutive dust echoes from a TDE. We model our observations following van Velzen et al. (2016) and find that the near-infrared light curve can be explained by concentric rings of thin dust within $\sim$0.1 parsecs of a 6e6 M$_{\odot}$ supermassive black hole (SMBH), among the smallest scales at which dust has been inferred near SMBHs. We find dust covering factors of order fc $\leq$ 2%, much lower than found for dusty tori of active galactic nuclei. These results highlight the potential of TDEs for uncovering the environments around black holes when including near-infrared observations in high-cadence transient studies

JWST Imaging of the Cartwheel Galaxy Reveals Dust Associated with SN 2021afdx

We present near- and mid-infrared (0.9-18 $\mu$m) photometry of supernova (SN) 2021afdx, which was imaged serendipitously with the James Webb Space Telescope (JWST) as part of its Early Release Observations of the Cartwheel Galaxy. Our ground-based optical observations show it is likely to be a Type IIb SN, the explosion of a yellow supergiant, and its infrared spectral energy distribution (SED) $\approx$200 days after explosion shows two distinct components, which we attribute to hot ejecta and warm dust. By fitting models of dust emission to the SED, we derive a dust mass of $(3.8_{-0.3}^{+0.5}) \times 10^{-3}\ M_\odot$, which is the highest yet observed in a Type IIb SN but consistent with other Type II SNe observed by the Spitzer Space Telescope. We also find that the radius of the dust is significantly larger than the radius of the ejecta, as derived from spectroscopic velocities during the photospheric phase, which implies that we are seeing an infrared echo off of preexisting dust in the progenitor environment, rather than dust newly formed by the SN. Our results show the power of JWST to address questions of dust formation in SNe, and therefore the presence of dust in the early universe, with much larger samples than have been previously possible.Comment: updated to match accepted versio

Highlights of the 1st Argentine Symposium of Young Bioinformatics Researchers (1SAJIB) organized by the ISCB RSG-Argentina

The 1st Argentine Symposium of Young Bioinformatics Researchers took place on 9-10 May 2016 at Universidad de Buenos Aires, Buenos Aires, Argentina. This event evolved from a previous meeting series known as Argentine Student Council Symposium that have been successfully organized since 2012 by the Regional Student Group of Argentina (RSG-Argentina). The change in name reflects the new vision of the organizing committee to gather together all students at Bachelor, Master and PhD levels, postdocs and researchers that are still not Principal Investigator. Here we summarize the main activities and outcomes from this year’s meeting and offer some insights into our future plans.Fil: Parra, Rodrigo Gonzalo. Max Planck Institute for Biophysical Chemistry; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Defelipe, Lucas Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Guzovsky, Ana Brenda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Monzón, Alexander. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cravero, Fiorella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Mancini, Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Moreyra, Nicolás Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Padilla Franzotti, Carla Luciana. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Revuelta, María Victoria. Cornell University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Freiberger, Maria Ines. Universidad Nacional de Entre Ríos. Facultad de Ingeniería; ArgentinaFil: Gonzalez, Nahuel H.. Universidad Nacional de Entre Ríos. Facultad de Ingeniería; ArgentinaFil: Gonzalez, German Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Orts, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Stocchi, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Hasenahuer, Marcia Anahí. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Teppa, Roxana Elin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Zea, Diego Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Palopoli, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

BASS XXXIX: Swift-BAT AGN with changing-look optical spectra

Changing-look (CL) AGN are unique probes of accretion onto supermassive black holes (SMBHs), especially when simultaneous observations in complementary wavebands allow investigations into the properties of their accretion flows. We present the results of a search for CL behaviour in 412 Swift-BAT detected AGN with multiple epochs of optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS). 125 of these AGN also have 14-195 keV ultra-hard X-ray light-curves from Swift-BAT which are contemporaneous with the epochs of optical spectroscopy. Eight CL events are presented for the first time, where the appearance or disappearance of broad Balmer line emission leads to a change in the observed Seyfert type classification. Combining with known events from the literature, 21 AGN from BASS are now known to display CL behaviour. Nine CL events have 14-195 keV data available, and five of these CL events can be associated with significant changes in their 14-195 keV flux from BAT. The ultra-hard X-ray flux is less affected by obscuration and so these changes in the 14-195 keV band suggest that the majority of our CL events are not due to changes in line-of-sight obscuration. We derive a CL rate of 0.7-6.2 per cent on 10-25 year time-scales, and show that many transitions happen within at most a few years. Our results motivate further multi-wavelength observations with higher cadence to better understand the variability physics of accretion onto SMBHs.Comment: 14 pages, 7 figures, plus appendix. v2: updated references. Published in MNRA

SN 2019ewu: A Peculiar Supernova with Early Strong Carbon and Weak Oxygen Features from a New Sample of Young SN Ic Spectra

With the advent of high cadence, all-sky automated surveys, supernovae (SNe) are now discovered closer than ever to their dates of explosion. However, young pre-maximum light follow-up spectra of Type Ic supernovae (SNe Ic), probably arising from the most stripped massive stars, remain rare despite their importance. In this paper we present a set of 49 optical spectra observed with the Las Cumbres Observatory through the Global Supernova Project for 6 SNe Ic, including a total of 17 pre-maximum spectra, of which 8 are observed more than a week before V-band maximum light. This dataset increases the total number of publicly available pre-maximum light SN Ic spectra by 25% and we provide publicly available SNID templates that will significantly aid in the fast identification of young SNe Ic in the future. We present detailed analysis of these spectra, including Fe II 5169 velocity measurements, O I 7774 line strengths, and continuum shapes. We compare our results to published samples of stripped supernovae in the literature and find one SN in our sample that stands out. SN 2019ewu has a unique combination of features for a SN Ic: an extremely blue continuum, high absorption velocities, a P-cygni shaped feature almost 2 weeks before maximum light that TARDIS radiative transfer modeling attributes to C II rather than H$\alpha$, and weak or non-existent O I 7774 absorption feature until maximum light.Comment: Submitted to the Astrophysical Journal. 15 pages, 6 figure

SN 2022jox: An extraordinarily ordinary Type II SN with Flash Spectroscopy

We present high cadence optical and ultraviolet observations of the Type II supernova (SN), SN 2022jox which exhibits early spectroscopic high ionization flash features of \ion{H}{1}, \ion{He}{2}, \ion{C}{4}, and \ion{N}{4} that disappear within the first few days after explosion. SN 2022jox was discovered by the Distance Less than 40 Mpc (DLT40) survey $\sim$0.75 days after explosion with followup spectra and UV photometry obtained within minutes of discovery. The SN reached a peak brightness of M$_V \sim$ $-$17.3 mag, and has an estimated $^{56}$Ni mass of 0.04 M$_{\odot}$, typical values for normal Type II SNe. The modeling of the early lightcurve and the strong flash signatures present in the optical spectra indicate interaction with circumstellar material (CSM) created from a progenitor with a mass loss rate of $\dot{M} \sim 10^{-3}-10^{-2}\ M_\odot\ \mathrm{yr}^{-1}$. There may also be some indication of late-time CSM interaction in the form of an emission line blueward of H$\alpha$ seen in spectra around 200 days. The mass-loss rate is much higher than the values typically associated with quiescent mass loss from red supergiants, the known progenitors of Type II SNe, but is comparable to inferred values from similar core collapse SNe with flash features, suggesting an eruptive event or a superwind in the progenitor in the months or years before explosion.Comment: Submitted to Ap

From Discovery to the First Month of the Type II Supernova 2023ixf: High and Variable Mass Loss in the Final Year Before Explosion

We present the discovery of Type II supernova (SN) 2023ixf in M101, among the closest core-collapse SNe in the last several decades, and follow-up photometric and spectroscopic observations in the first month of its evolution. The light curve is characterized by a rapid rise ($\approx5$ days) to a luminous peak ($M_V\approx-18$ mag) and plateau ($M_V\approx-17.6$ mag) extending to $30$ days with a smooth decline rate of $\approx0.03$ mag day$^{-1}$. During the rising phase, $U-V$ color shows blueward evolution, followed by redward evolution in the plateau phase. Prominent flash features of hydrogen, helium, carbon, and nitrogen dominate the spectra up to $\approx5$ days after first light, with a transition to a higher ionization state in the first $\approx2$ days. Both the $U-V$ color and flash ionization states suggest a rise in the temperature, indicative of a delayed shock-breakout inside dense circumstellar material (CSM). From the timescales of CSM interaction, we estimate its compact radial extent of $\sim(3-7)\times10^{14}$ cm. We then construct numerical light-curve models based on both continuous and eruptive mass-loss scenarios shortly before explosion. For the continuous mass-loss scenario, we infer a range of mass-loss history with $0.1-1.0$ $M_\odot {\rm yr}^{-1}$ in the final $2-1$ years before explosion, with a potentially decreasing mass loss of $0.01-0.1$ $M_\odot {\rm yr}^{-1}$ in $\sim0.7-0.4$ years towards the explosion. For the eruptive mass-loss scenario, we favor eruptions releasing $0.3-1$ $M_\odot$ of the envelope at about a year before explosion, which result in CSM with mass and extent similar to the continuous scenario. We discuss the implications of the available multi-wavelength constraints obtained thus far on the progenitor candidate and SN 2023ixf to our variable CSM models.Comment: 15 pages, 5 figures, submitted to ApJ

JWST Imaging of the Cartwheel Galaxy Reveals Dust Associated with SN 2021afdx

We present near- and mid-infrared (0.9–18 μm) photometry of supernova (SN) 2021afdx, which was imaged serendipitously with the James Webb Space Telescope (JWST) as part of its Early Release Observations of the Cartwheel Galaxy. Our ground-based optical observations show it is likely to be a Type IIb SN, the explosion of a yellow supergiant, and its infrared spectral energy distribution (SED) ≈200 days after explosion shows two distinct components, which we attribute to hot ejecta and warm dust. By fitting models of dust emission to the SED, we derive a dust mass of $({3.8}_{-0.3}^{+0.5})\times {10}^{-3}\ {M}_{\odot }$, which is the highest yet observed in a Type IIb SN but consistent with other Type II SNe observed by the Spitzer Space Telescope. We also find that the radius of the dust is significantly larger than the radius of the ejecta, as derived from spectroscopic velocities during the photospheric phase, which implies that we are seeing an infrared echo off of preexisting dust in the progenitor environment, rather than dust newly formed by the SN. Our results show the power of JWST to address questions of dust formation in SNe, and therefore the presence of dust in the early universe, with much larger samples than have been previously possible

Shock Cooling and Possible Precursor Emission in the Early Light Curve of the Type II SN 2023ixf

We present the densely sampled early light curve of the Type II supernova (SN) 2023ixf, first observed within hours of explosion in the nearby Pinwheel Galaxy (Messier 101; 6.7 Mpc). Comparing these data to recently updated models of shock cooling emission, we find that the progenitor likely had a radius of $410 \pm 10\ R_\odot$ (statistical uncertainty only), consistent with a red supergiant. These models provide a good fit to the data starting about 1 day after the explosion, despite the fact that the classification spectrum shows signatures of circumstellar material around SN 2023ixf during that time. Photometry during the first day after the explosion, provided almost entirely by amateur astronomers, does not agree with the shock cooling models or a simple power-law rise fit to data after 1 day. We consider the possible causes of this discrepancy, including precursor activity from the progenitor star, circumstellar interaction, and emission from the shock before or after it breaks out of the stellar surface. The very low luminosity ($-11\mathrm{\ mag} > M > -14\mathrm{\ mag}$) and short duration of the initial excess leads us to prefer a scenario related to prolonged emission from the SN shock traveling through the progenitor system.Comment: submitted to ApJ

Near-Infrared and Optical Observations of Type Ic SN 2021krf: Luminous Late-time Emission and Dust Formation

We present near-infrared (NIR) and optical observations of the Type Ic supernova (SN Ic) SN 2021krf obtained between days 13 and 259 at several ground-based telescopes. The NIR spectrum at day 68 exhibits a rising $K$-band continuum flux density longward of $\sim$ 2.0 $\mu$m, and a late-time optical spectrum at day 259 shows strong [O I] 6300 and 6364 \r{A} emission-line asymmetry, both indicating the presence of dust, likely formed in the SN ejecta. We estimate a carbon-grain dust mass of $\sim$ 2 $\times$ 10$^{-5}$ M$_{\odot}$ and a dust temperature of $\sim$ 900 - 1200 K associated with this rising continuum and suggest the dust has formed in SN ejecta. Utilizing the one-dimensional multigroup radiation hydrodynamics code STELLA, we present two degenerate progenitor solutions for SN 2021krf, characterized by C-O star masses of 3.93 and 5.74 M$_{\odot}$, but with the same best-fit $^{56}$Ni mass of 0.11 M$_{\odot}$ for early times (0-70 days). At late times (70-300 days), optical light curves of SN 2021krf decline substantially more slowly than that expected from $^{56}$Co radioactive decay. Lack of H and He lines in the late-time SN spectrum suggests the absence of significant interaction of the ejecta with the circumstellar medium. We reproduce the entire bolometric light curve with a combination of radioactive decay and an additional powering source in the form of a central engine of a millisecond pulsar with a magnetic field smaller than that of a typical magnetar.Comment: Accepted for publication in ApJ, 27 pages, 21 figures, 6 tables. Previous arXiv submission (arXiv:2211.00205) replaced after acceptanc