Search

We present an in-depth study of the late-time near-infrared plateau in Type Ia supernovae (SNe Ia), which occurs between 70-500 d. We double the existing sample of SNe Ia observed during the late-time near-infrared plateau with new observations taken with the Hubble Space Telescope, Gemini, New Technology Telescope, the 3.5m Calar Alto Telescope, and the Nordic Optical Telescope. Our sample consists of 24 nearby SNe Ia at redshift < 0.025. We are able to confirm that no plateau exists in the Ks band for most normal SNe Ia. SNe Ia with broader optical light curves at peak tend to have a higher average brightness on the plateau in J and H, most likely due to a shallower decline in the preceding 100 d. SNe Ia that are more luminous at peak also show a steeper decline during the plateau phase in H. We compare our data to state-of-the-art radiative transfer models of nebular SNe Ia in the near-infrared. We find good agreement with the sub-Mch model that has reduced non-thermal ionisation rates, but no physical justification for reducing these rates has yet been proposed. An analysis of the spectral evolution during the plateau demonstrates that the ratio of [Fe II] to [Fe III] contribution in a near-infrared filter determines the light curve evolution in said filter. We find that overluminous SNe decline slower during the plateau than expected from the trend seen for normal SNe Ia, 17 pages, 8 figures, Accepted for publication in MNRAS

The observed diversity in Type Ia supernovae (SNe Ia) – the thermonuclear explosions of carbon–oxygen white dwarf stars used as cosmological standard candles – is currently met with a variety of explosion models and progenitor scenarios. To help improve our understanding of whether and how often different models contribute to the occurrence of SNe Ia and their assorted properties, we present a comprehensive analysis of seven nearby SNe Ia. We obtained one to two epochs of optical spectra with Gemini Observatory during the nebular phase (>200 d past peak) for each of these events, all of which had time series of photometry and spectroscopy at early times (the first ∼8 weeks after explosion). We use the combination of early- and late-time observations to assess the predictions of various models for the explosion (e.g. double-detonation, off-centre detonation, stellar collisions), progenitor star (e.g. ejecta mass, metallicity), and binary companion (e.g. another white dwarf or a non-degenerate star). Overall, we find general consistency in our observations with spherically symmetric models for SN Ia explosions, and with scenarios in which the binary companion is another degenerate star. We also present an in-depth analysis of SN 2017fzw, a member of the subgroup of SNe Ia which appear to be transitional between the subluminous ‘91bg-like’ events and normal SNe Ia, and for which nebular-phase spectra are rare., The international Gemini Observatory, a program of NSF’s NOIRLab, is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). The observations were made under Gemini programs GS-2018A-Q-315, GS-2018B-Q-209, and GN-2018B-Q-213 (optical spectra), and GS-2018B-Q-218 (NIR spectrum). The data and calibration files were obtained from the Gemini Observatory Archive at NSF’s NOIRLab, and processed using the Gemini IRAF package. This work makes use of observations from the Las Cumbres Observatory global telescope network. The Las Cumbres Observatory team is supported by NSF grants AST-1911225 and AST-1911151. We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team. MLG and TDK acknowledge support from the DIRAC Institute in the Department of Astronomy at the University of Washington. The DIRAC Institute is supported through generous gifts from the Charles and Lisa Simonyi Fund for Arts and Sciences, and the Washington Research Foundation. MLG and TDK thank Brigitta Sipőcz for assistance with implementing the Bayesian Information Criterion. Time domain research by DJS is supported by NSF grants AST-1821987, 1813466, and 1908972, and by the Heising–Simons Foundation under grant #2020-1864. LG acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253GA-I00. XW is supported by the National Science Foundation of China (NSFC grants 12033003 and 11633002), the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002), and the Tencent XPLORER Prize.

Background Delayed door-to-balloon (DTB) time and deterioration of in-hospital mortality during the coronavirus disease 2019 (COVID-19) pandemic have been reported. Little is known about the impact of changes in in-hospital medical management before primary percutaneous coronary intervention (PCI) for COVID-19 such as screening test (antigen or polymerase chain reaction (PCR) tests, chest CT for excluding the pneumoniae) and primary PCI under full personal protective equipment (PPE) on DTB time and in-hospital mortality. Purpose The purpose of this study was to evaluate the impact of in-hospital medical management for COVID-19 on DTB time and in-hospital mortality during COVID-19 pandemic period. Methods We compared DTB time and in-hospital mortality of 502 ST-elevation myocardial infarction (STEMI) patients during COVID-19 pandemic (February 2020 and January 2021) with 2035 STEMI patients before pandemic (February 2016 and January 2020) using date from Mie ACS registry, a retrospective and multicenter registry. Results The COVID-19 screening tests before primary PCI and/or primary PCI under full PPE was performed on 173/502 (34.5%) patients (antigen or PCR tests; 39 (7.8%), chest CT; 156 (31.3%), full PPE; 11 (2.2%)). These patients had lower rate of achievement of DTB time ≤90 min compared with others (Figure 1A). Moreover, In-hospital management of COVID-19 screening tests and/or primary PCI under full PPE was an independent factor of DTB time>90 min with odds ratio of 1.94 (95% confidential interval: 1.37–2.76, p Conclusion In-hospital medical management for COVID-19 screening tests before primary PCI and/or primary PCI under full PPE was the independent factor of DTB time>90 min. This study reinforces the need to focus efforts on shortening DTB time, while controlling the epidemic of infection. Funding Acknowledgement Type of funding sources: None.

S. J. Brennan et al., We present the bolometric light curve, identification and analysis of the progenitor candidate, and preliminary modelling of AT 2016jbu (Gaia16cfr). We find a progenitor consistent with a ∼ 22–25 M⊙ yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong Hα emission consistent with pre-existing circumstellar material. The age of the environment, as well as the resolved stellar population surrounding AT 2016jbu, supports a progenitor age of >10 Myr, consistent with a progenitor mass of ∼22 M⊙. A joint analysis of the velocity evolution of AT 2016jbu and the photospheric radius inferred from the bolometric light curve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity ∼650 km s−1, while the second, more energetic event ejected material at ∼4500 km s−1. Whether the latter is the core collapse of the progenitor remains uncertain. We place a limit on the ejected 56Ni mass of, SJB acknowledges support from Science Foundation Ireland and the Royal Society (RS-EA/3471). MF is supported by a Royal Society–Science Foundation Ireland University Research Fellowship. TMB was funded by CONICYT PFCHA/DOCTORADOBECAS CHILE/2017-72180113 and acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2020-115253GA-I00 HOSTFLOWS project, and Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016. KM is funded by the EU H2020 ERC grant no. 758638. TWC acknowledges EU Funding under Marie Skłodowska–Curie grant H2020-MSCA-IF-2018-842471, and thanks Thomas Krühler for GROND data reduction. MN is supported by a Royal Astronomical Society Research Fellowship. BJS is supported by NSF grants AST-1908952, AST-1920392, AST-1911074, and NASA award 80NSSC19K1717. MS is supported by generous grants from Villum FONDEN (13261,28021) and by a project grant (8021-00170B) from the Independent Research Fund Denmark. LH acknowledges support for Watcher from Science Foundation Ireland grant 07/RFP/PHYF295. Time-domain research by DJS is supported by NSF grants AST-1821987, 1813466, and 1908972, and by the Heising–Simons Foundation under grant #2020-1864. NER acknowledges support from MIUR, PRIN 2017 (grant 20179ZF5KS). Support for JLP is provided in part by ANID through the Fondecyt regular grant 1191038 and through the Millennium Science Initiative grant ICN12_009, awarded to The Millennium Institute of Astrophysics, MAS. LG acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253GA-I00. DAH and DH are supported by AST-1911151, AST19-11225, and NASA Swift grant 80NSSC19K1639. GP acknowledges support by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. LT acknowledges support from MIUR (PRIN 2017 grant 20179ZF5KS). Support for TW-SH was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51458.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. HK was funded by the Academy of Finland projects 324504 and 328898. This research made use of ASTROPY,8 a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013; Price-Whelan et al. 2018). This research made use of data provided by Astrometry.net.9 Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO 3D), through project number CE170100013. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the Telescope Access Program (TAP) funded by the NAOC, CAS, and the Special Fund for Astronomy from the Ministry of Finance. This work was partially supported by Polish NCN grants: Harmonia No. 2018/30/M/ST9/00311 and Daina No. 2017/27/L/ST9/03221. This work made use of v2.2.1 of the Binary Population and Spectral Synthesis (BPASS) models as described in Eldridge et al. (2017) and Stanway & Eldridge (2018). This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 15645. Observations were also obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESAC/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA). This research has made use of the SVO Filter Profile Service10 supported from the Spanish MINECO through grant AYA2017-84089.

We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT 2018bwo, AT 2021afy, and AT 2021blu. AT 2018bwo was discovered in NGC 45 (at about 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 1040 erg s−1. AT 2021afy, hosted by UGC 10043 (∼49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(±0.6)×1041 erg s−1. Finally, for AT 2021blu in UGC 5829 (∼8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT 2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of LRN AT 2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5 × 1040 erg s−1, which is half of that of AT 2021afy. The spectra of AT 2021afy and AT 2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT 2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT 2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from about 13 M⊙ for AT 2018bwo, to 14−1+4 M⊙ for AT 2021blu, and over 40 M⊙ for AT 2021afy.

We present a sample of Type Icn supernovae (SNe Icn), a newly-discovered class of transients characterized by their interaction with H- and He-poor circumstellar material (CSM). This sample is the largest collection of SNe Icn to date and includes observations of two published objects (SN 2019hgp and SN 2021csp) as well as two objects (SN 2019jc and SN 2021ckj) not yet published in the literature. The SNe Icn display a range of peak luminosities, rise times, and decline rates, as well as diverse late-time spectral features. To investigate their explosion and progenitor properties we fit their bolometric light curves to a semi-analytical model consisting of luminosity inputs from circumstellar interaction and radioactive decay of $^{56}$Ni. We infer low ejecta masses ($\lesssim$ 2 M$_\odot$) and $^{56}$Ni masses ($\lesssim$ 0.04 M$_\odot$) from the light curves, suggesting that normal stripped-envelope supernova (SESN) explosions within a dense CSM cannot be the underlying mechanism powering SNe Icn. Additionally, we find that an upper limit on the star formation rate density at the location of SN 2019jc lies at the lower end of a distribution of SESNe, in conflict with a massive star progenitor of this object. Based on the estimated ejecta masses, $^{56}$Ni masses, and explosion site properties, we favor a low-mass, ultra-stripped star as the progenitor of some SNe Icn. For others, we suggest that a Wolf-Rayet star progenitor may better explain their observed properties. This study demonstrates that multiple progenitor channels may produce SNe Icn and other interaction-powered transients., 25 pages, 11 figures, published in ApJ

Brennan, S. J. et al (ASTROPY Collaboration), We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼-18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s-1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s-1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He i, and Ca ii. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients., SJB acknowledges support from Science Foundation Ireland and the Royal Society (RS-EA/3471). MF is supported by a Royal Society - Science Foundation Ireland University Research Fellowship. TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113 and acknowledges their financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2020-115253GA-I00 HOSTFLOWS project, and from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016. KM is funded by the EU H2020 ERC grant no. 758638. TWC acknowledges the EU Funding under Marie Skłodowska-Curie grant H2020-MSCA-IF-2018-842471, and thanks to Thomas Krühler for GROND data reduction. MN is supported by a Royal Astronomical Society Research Fellowship. BJS is supported by NSF grants AST-1908952, AST-1920392, AST-1911074, and NASA award 80NSSC19K1717. MS is supported by generous grants from Villum FONDEN (13261, 28021) and by a project grant (8021-00170B) from the Independent Research Fund Denmark. LH acknowledges support for Watcher from Science Foundation Ireland grant 07/RFP/PHYF295. Time domain research by DJS is supported by NSF grants AST-1821987, 1813466, and 1908972, and by the Heising-Simons Foundation under grant #2020-1864. NER acknowledges support from MIUR, PRIN 2017 (grant 20179ZF5KS). LG acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253GA-I00. Support for TW-SH was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51458.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Support for JLP is provided in part by ANID through the Fondecyt regular grant 1191038 and through the Millennium Science Initiative grant ICN12_009, awarded to The Millennium Institute of Astrophysics, MAS. DAH and DH are supported by AST-1911151, AST19-11225, and NASA Swift grant 80NSSC19K1639. GP acknowledge support by the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. LT acknowledges support from MIUR (PRIN 2017 grant 20179ZF5KS). HK was funded by the Academy of Finland projects 324504 and 328898.

[Abridged] We classify AT 2020zso as a TDE based on the blackbody evolution inferred from UV/optical photometric observations, and spectral line content and evolution. We identify transient, double-peaked Bowen (N III), He I, He II and Halpha emission lines. We model medium resolution optical spectroscopy of the He II (after careful deblending of the N III contribution) and Halpha lines during the rise, peak and early decline of the light curve using relativistic, elliptical accretion disk models. We find that the spectral evolution before peak can be explained by optical depth effects consistent with an outflowing, optically thick Eddington envelope. Around peak the envelope reaches its maximum extent (approximately 10^15 or 3000-6000 gravitational radii for an inferred black hole mass of 5-10 10^5) and becomes optically thin. The Halpha and He II emission lines at and after peak can be reproduced with a highly inclined (i=85+-5 degrees), highly elliptical (e=0.97+-0.01) and relatively compact (Rin = several 100 Rg and Rout = several 1000 Rg ) accretion disk. Overall, the line profiles suggest a highly elliptical geometry for the new accretion flow, consistent with theoretical expectations of newly formed TDE disks. We quantitatively confirm, for the first time, the high inclination nature of a Bowen (and X-ray dim) TDE, consistent with the unification picture of TDEs where the inclination largely determines the observational appearance. Rapid line profile variations rule out the binary SMBH hypothesis as the origin of the eccentricity; these results thus provide a direct link between a TDE in an AGN and the eccentric accretion disk. We illustrate for the first time how optical spectroscopy can be used to constrain the black hole spin, through (the lack of) disk precession signatures (changes in inferred inclination) - and rule out high black hole spin values (a < 0.8)., 20 pages, 15 figures and 5 tables. Accepted for publication in A&A. The spectra will be made publicly available through WISErep

In this study we present the results of a five-year follow-up campaign of the long-lived type IIn supernova SN 2017hcc, found in a spiral dwarf host of near-solar metallicity. The long rise time (57 $\pm$ 2 days, ATLAS $o$ band) and high luminosity (peaking at $-$20.78 $\pm$ 0.01 mag in the ATLAS $o$ band) point towards an interaction of massive ejecta with massive and dense circumstellar material (CSM). The evolution of SN 2017hcc is slow, both spectroscopically and photometrically, reminiscent of the long-lived type IIn, SN 2010jl. An infrared (IR) excess was apparent soon after the peak, and blueshifts were noticeable in the Balmer lines starting from a few hundred days, but appeared to be fading by around +1200 days. We posit that an IR light echo from pre-existing dust dominates at early times, with some possible condensation of new dust grains occurring at epochs >$\sim$+800 days., Accepted to A&A

Tucker et al., On 2019 August 14 at 21:10:39 UTC, the LIGO/Virgo Collaboration (LVC) detected a possible neutron star–black hole merger (NSBH), the first ever identified. An extensive search for an optical counterpart of this event, designated GW190814, was undertaken using the Dark Energy Camera on the 4 m Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory. Target of Opportunity interrupts were issued on eight separate nights to observe 11 candidates using the 4.1 m Southern Astrophysical Research (SOAR) telescope's Goodman High Throughput Spectrograph in order to assess whether any of these transients was likely to be an optical counterpart of the possible NSBH merger. Here, we describe the process of observing with SOAR, the analysis of our spectra, our spectroscopic typing methodology, and our resultant conclusion that none of the candidates corresponded to the gravitational wave merger event but were all instead other transients. Finally, we describe the lessons learned from this effort. Application of these lessons will be critical for a successful community spectroscopic follow-up program for LVC observing run 4 (O4) and beyond., Funding for the DES Projects has been provided by the DOE and NSF(USA), MEC/MICINN/MINECO (Spain), STFC (UK), HEFCE(UK). NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), DFG (Germany) and the Collaborating Institutions in the Dark Energy Survey. The DES Data Management System is supported by the NSF under grant Nos. AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, and Centro de Excelencia SEV-2016-0588, SEV-2016-0597 and MDM-2015-0509. Research leading to these results has received funding from the ERC under the EU's 7th Framework Programme including grants ERC 240672, 291329 and 306478. I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement number 852097), from the Israel Science Foundation (grant number 2752/19), from the United States–Israel Binational Science Foundation (BSF), and from the Israeli Council for Higher Education Alon Fellowship.

We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6 × 1041 erg s−1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊙ progenitor candidate with log (L/L⊙) = 5.0 dex and Teff = 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17–24 M⊙ primary component.

SN 2018hti was a very nearby (z = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of −21.7 mag in r band at maximum. The densely sampled pre-maximum light curves of SN 2018hti show a slow luminosity evolution and constrain the rise time to ∼50 rest-frame d. We fitted synthetic light curves to the photometry to infer the physical parameters of the explosion of SN 2018hti for both the magnetar and the CSM-interaction scenarios. We conclude that one of two mechanisms could be powering the luminosity of SN 2018hti; interaction with ∼10 M⊙ of circumstellar material or a magnetar with a magnetic field of Bp∼ 1.3 × 1013 G, and initial period of Pspin∼ 1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ∼40M⊙ progenitor star., MG is supported by the EU Horizon 2020 research and innovation programme under grant agreement No 101004719. MS acknowledges the Infrared Telescope Facility, which is operated by the University of Hawaii under contract 80HQTR19D0030 with the National Aeronautics and Space Administration. NER acknowledges support from MIUR, PRIN 2017 (grant 20179ZF5KS). TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. AJ acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program (ERC Starting Grant. AR acknowledges support from ANID BECAS/DOCTORADO NACIONAL 21202412. Y-Z Cai is funded by China Postdoctoral Science Foundation (grant no. 2021M691821). T-WC acknowledges the EU Funding under Marie Skłodowska-Curie grant H2020-MSCA-IF-2018-842471. KM is funded by the EU H2020 ERC grant no. 758638. GP is supported by ANID - Millennium Science Initiative - ICN12_009. We thank the staff at the different observatories for performing the observations. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO+ (the advanced Public ESO Spectroscopic Survey for Transient Objects). ePESSTO+ observations were obtained under ESO program id 199.D-0143 (PI: Inserra). Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. This work uses observations from the Las Cumbres Observatory network. The LCO team is supported by NSF grants AST-1911225 and AST-1911151.

We propose a new technique to detect multiple targets from full-waveform airborne laser scanner. We introduce probability hypothesis density (PHD) filter, a type of Bayesian filtering, by which we can estimate the number of targets and their positions simultaneously. PHD filter overcomes some limitations of conventional Gaussian decomposition method; PHD filter doesn’t require a priori knowledge on the number of targets, assumption of parametric form of the intensity distribution. In addition, it can take a similarity between successive irradiations into account by modelling relative positions of the same targets spatially. Firstly we explain PHD filter and particle filter implementation to it. Secondly we formulate the multi-target detection problem on PHD filter by modelling components and parameters within it. At last we conducted the experiment on real data of forest and vegetation, and confirmed its ability and accuracy.

This paper studies interconnect structures for long-distance signal transmission that exploit transmission line effects. We take up two basic structures; micro-strip and coplanar lines, and examine the attenuation properties and inductive coupling noise. We experimentally reveal the relationship between interconnect length and required interconnect resource in 35 nm and 130 nm technologies. We can see that the interconnect size required for 10 mm signal transmission is somewhat larger than that of the current top-metal interconnects.

Armstrong, P., et al., SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of ∼ 50-290R⊙, and an envelope mass of ∼ 0-1.7M⊙. SN 2017jgh likely had a shock velocity of ∼7500-10 300 km s-1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of ∼ 50-330R⊙, an envelope mass of ∼ 0.3-1.7M⊙ and a shock velocity of ∼9000-15 000 km s-1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated., BET and his group were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. The UCSC transient team is supported in part by NASA/K2 grants 80NSSC18K0303 and 80NSSC19K0113, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, and by a fellowship from the David and Lucile Packard Foundation to RJF. DOJ acknowledges support provided by NASA Hubble Fellowship grant HST-HF2-51462.001, which is awarded by the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. IA is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 852097), from the Israel Science Foundation (grant number 2752/19), from the United States - Israel Binational Science Foundation (BSF), and from the Israeli Council for Higher Education Alon Fellowship. MRD acknowledges support from the NSERC through grant RGPIN-2019-06186, the Canada Research Chairs Program, the Canadian Institute for Advanced Research (CIFAR), and the Dunlap Institute at the University of Toronto. DAC acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant DGE1339067. This project has been supported by the LP2018-7 Lendület grant of the Hungarian Academy of Sciences. LG acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253GA-I00. BJS is supported by NASA grant 80NSSC19K1717 and NSF grants AST-1920392 and AST-1911074. Support for TWSH was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51458.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Research by SV is supported by NSF grants AST-1813176 and AST-2008108. LK acknowledges the financial support of the Hungarian National Research, Development and Innovation Office grant NKFIH PD-134784. LK and ZsB are supported by the Jànos Bolyai Research Scholarship of the Hungarian Academy of Sciences. The Konkoly team has been supported by the project ‘Transient Astrophysical Objects’ GINOP 2.3.2-15-2016-00033 of the National Research, Development and Innovation Office (NKFIH), Hungary, funded by the European Union. SWJ acknowledges support from US National Science Foundation award AST-1615455. This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported from the Spanish MINECO through grant AYA2017-84089. The LCO team is supported by NASA grant 80NSSC19K0119 and NSF grants AST-1911225 and AST-1911151.

Rapidly evolving transients, or objects that rise and fade in brightness on timescales two to three times shorter than those of typical Type Ia or Type II supernovae (SNe), have uncertain progenitor systems and powering mechanisms. Recent studies have noted similarities between rapidly evolving transients and Type Ibn SNe, which are powered by ejecta interacting with He-rich circumstellar material (CSM). In this work we present multiband photometric and spectroscopic observations from Las Cumbres Observatory and Swift of four fast-evolving Type Ibn SNe. We compare these observations with those of rapidly evolving transients identified in the literature. We discuss several common characteristics between these two samples, including their light curve and color evolution as well as their spectral features. To investigate a common powering mechanism we construct a grid of analytical model light curves with luminosity inputs from CSM interaction as well as $^{56}$Ni radioactive decay. We find that models with ejecta masses of $\approx 1-3$ M$_\odot$, CSM masses of $\approx 0.2-1$ M$_\odot$, and CSM radii of $\approx 20-65$ au can explain the diversity of peak luminosities, rise times, and decline rates observed in Type Ibn SNe and rapidly evolving transients. This suggests that a common progenitor system$-$the core collapse of a high-mass star within a dense CSM shell$-$can reproduce the light curves of even the most luminous and fast-evolving objects, such as AT 2018cow. This work is one of the first to reproduce the light curves of both SNe Ibn and other rapidly evolving transients with a single model., 24 pages, 11 figures, published in ApJ

This paper is the data release of a new sample of 140 type Ia supernovae (SNe Ia) from the LaSilla-QUEST/Las Cumbres Observatory (LCO) collaboration. The discovery of the supernovae came from the LaSilla-QUEST variability survey, the ASASSN survey, as well as smaller low redshift supernova surveys. All of the supernovae in this sample were spectroscopically identified as SNe Ia using spectra from the PESSTO survey using the 3.5 m NTT telescope at LaSilla and spectra from the LCO 2 m Faulkes telescopes. The light-curves were obtained from a rapid cadence photometric follow up of the supernovae with the 9 LCO 1 m telescopes located at various observatories around the globe. Reference images of the host galaxies were taken approximately a year after the supernova have faded to allow precise galaxy background subtraction from the supernova magnitudes. The supernovae in this sample were discovered over a seven year period from 2012 October to 2019 June, and the last galaxy reference images were taken before 2020 June.