Search

We present the discovery of as-of-yet non-repeating Fast Radio Burst (FRB), FRB 20210117A, with the Australian Square Kilometer Array Pathfinder (ASKAP) as a part of the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey. The sub-arcsecond localization of the burst led to the identification of its host galaxy at a $z=0.214(1)$. This redshift is much lower than what would be expected for a source dispersion measure (DM) of 729 pc cm$^{-3}$, given typical contributions from the intergalactic medium and the host galaxy. Optical observations reveal the host to be a dwarf galaxy with little on-going star formation, very different to the dwarf host galaxies of known repeating FRBs 20121102A, and 20190520B. We find an excess DM contribution from the host and attribute it to the FRB's local environment. We do not find any radio emission from the FRB site or host galaxy. The low magnetized environment and lack of a persistent radio source (PRS) indicate that the FRB source is older than those found in other dwarf host galaxies, and establish the diversity of FRB sources in dwarf galaxy environments. We find our observations to be fully consistent with the hypernebula model, where the FRB is powered by accretion-jet from a hyper-accreting black hole. Finally, our high-time resolution analysis reveals burst characteristics similar to those seen in repeating FRBs. We encourage follow-up observations of FRB 20210117A to establish any repeating nature., 15 pages, 9 figures, 2 Tables

We introduce the Australia Telescope Compact Array (ATCA) rapid-response mode by presenting the first successful trigger on the short-duration gamma-ray burst (GRB) 181123B. Early-time radio observations of short GRBs may provide vital insights into the radio afterglow properties of Advanced LIGO- and Virgo-detected gravitational wave events, which will in turn inform follow-up strategies to search for counterparts within their large positional uncertainties. The ATCA was on target within 12.6 hr post-burst, when the source had risen above the horizon. While no radio afterglow was detected during the 8.3 hr observation, we obtained force-fitted flux densities of $7 \pm 12$ and $15 \pm 11~\mu$Jy at 5.5 and 9 GHz, respectively. Afterglow modelling of GRB 181123B showed that the addition of the ATCA force-fitted radio flux densities to the Swift X-ray Telescope detections provided more stringent constraints on the fraction of thermal energy in the electrons (log$\epsilon_e = -0.75^{+0.39}_{-0.40}$ rather than log$\epsilon_e = -1.13^{+0.82}_{-1.2}$ derived without the inclusion of the ATCA values), which is consistent with the range of typical $\epsilon_e$ derived from GRB afterglow modelling. This allowed us to predict that the forward shock may have peaked in the radio band $\sim10$ days post-burst, producing detectable radio emission $\gtrsim3-4$ days post-burst. Overall, we demonstrate the potential for extremely rapid radio follow-up of transients and the importance of triggered radio observations for constraining GRB blast wave properties, regardless of whether there is a detection, via the inclusion of force-fitted radio flux densities in afterglow modelling efforts., Comment: 15 pages, 7 figures, accepted for publication in MNRAS

Ni, Y. Q., et al., Type Ia supernovae are thermonuclear explosions of white dwarf stars. They play a central role in the chemical evolution of the Universe and are an important measure of cosmological distances. However, outstanding questions remain about their origins. Despite extensive efforts to obtain natal information from their earliest signals, observations have thus far failed to identify how the majority of them explode. Here, we present infant-phase detections of SN 2018aoz from a very low brightness of −10.5 AB absolute magnitude, revealing a hitherto unseen plateau in the B band that results in a rapid redward colour evolution between 1.0 and 12.4 hours after the estimated epoch of first light. The missing B-band flux is best explained by line-blanket absorption from Fe-peak elements in the outer 1% of the ejected mass. The observed B − V colour evolution of the supernova also matches the prediction from an over-density of Fe-peak elements in the same outer 1% of the ejected mass, whereas bluer colours are expected from a purely monotonic distribution of Fe-peak elements. The presence of excess nucleosynthetic material in the extreme outer layers of the ejecta points to enhanced surface nuclear burning or extended subsonic mixing processes in some normal type Ia SN explosions., D.-S.M., M.R.D. and C.D.M. are supported by Discovery Grants from the Natural Sciences and Engineering Research Council of Canada. D.-S.M. was supported in part by a Leading Edge Fund from the Canadian Foundation for Innovation (project no. 30951). M.R.D. was supported in part by the Canada Research Chairs Program, the Canadian Institute for Advanced Research (CIFAR) and the Dunlap Institute at the University of Toronto. D.J.S. acknowledges support by NSF grant nos. AST-1821987, 1821967 and 1908972 and from the Heising–Simons Foundation under grant no. 2020-1864. S.G.-G. acknowledges support by FCT under project CRISP PTDC/FIS-AST-31546 and project UIDB/00099/2020. H.S.P. was supported in part by a National Research Foundation (NRF) of Korea grant funded by the Korean government (MSIT, Ministry of Science and ICT; no. NRF-2019R1F1A1058228). P.J.B. acknowledges support from the Swift GI program 80NSSC19K0316. S.V., Y.D. and K.A.B. acknowledge support by NSF grant nos. AST-1813176 and AST-2008108. C.M. acknowledges support by NSF grant AST-1313484. I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, from the Israel Science Foundation (grant nos. 2108/18 and 2752/19), from the United States – Israel Binational Science Foundation (BSF) and from an Israeli Council for Higher Education Alon Fellowship. R.L.B. acknowledges support by NASA through Hubble Fellowship grant no. 51386.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract no. NAS 5-26555. A.G.-Y. acknowledges support from the European Union via ERC grant no. 725161, the ISF GW Excellence Center, an IMOS space infrastructure grant and BSF/Transformative and GIF grants, as well as from the Benoziyo Endowment Fund for the Advancement of Science, the Deloro Institute for Advanced Research in Space and Optics, the Veronika A. Rabl Physics Discretionary Fund, P. and T. Gardner, the Yeda-Sela Center for Basic Research and a WIS-CIT joint research grant. A.G.-Y. is the recipient of the Helen and Martin Kimmel Award for Innovative Investigation. L.G. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, the European Social Fund (ESF) ‘Investing in your future’ under the 2019 Ramón y Cajal program RYC2019-027683-I and the PID2020-115253GA-I00 HOSTFLOWS project, as well as from the Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016. G.P. acknowledges support from the Millennium Science Initiative through grant no. IC120009. J.A. is supported by the Stavros Niarchos Foundation (SNF) and the Hellenic Foundation for Research and Innovation (HFRI) under the 2nd Call of ‘Science and Society’ Action ‘Always strive for excellence – Theodoros Papazoglou’ (project no. 01431).

We present the localization and host galaxies of one repeating and two apparently non-repeating Fast Radio Bursts. FRB20180301A was detected and localized with the Karl G. Jansky Very Large Array to a star-forming galaxy at $z=0.3304$. FRB20191228A, and FRB20200906A were detected and localized by the Australian Square Kilometre Array Pathfinder to host galaxies at $z=0.2430$ and $z=0.3688$, respectively. We combine these with 13 other well-localized FRBs in the literature, and analyze the host galaxy properties. We find no significant differences in the host properties of repeating and apparently non-repeating FRBs. FRB hosts are moderately star-forming, with masses slightly offset from the star-forming main-sequence. Star formation and low-ionization nuclear emission-line region (LINER) emission are major sources of ionization in FRB host galaxies, with the former dominant in repeating FRB hosts. FRB hosts do not track stellar mass and star formation as seen in field galaxies (more than 95% confidence). FRBs are rare in massive red galaxies, suggesting that progenitor formation channels are not solely dominated by delayed channels which lag star formation by Gigayears. The global properties of FRB hosts are indistinguishable from core-collapse supernovae (CCSNe) and short gamma-ray bursts (SGRBs) hosts, and the spatial offset (from galaxy centers) of FRBs is mostly inconsistent with that of the Galactic neutron star population (95% confidence). The spatial offsets of FRBs (normalized to the galaxy effective radius) also differ from those of globular clusters (GCs) in late- and early-type galaxies with 95% confidence., 27 pages, 12 figures, 8 tables. Accepted for publication in the Astrophysical Journal

We present the largest and most homogeneous collection of near-infrared (NIR) spectra of Type Ia supernovae (SNe Ia): 339 spectra of 98 individual SNe obtained as part of the Carnegie Supernova Project-II. These spectra, obtained with the FIRE spectrograph on the 6.5 m Magellan Baade telescope, have a spectral range of 0.8--2.5 $\mu$m. Using this sample, we explore the NIR spectral diversity of SNe Ia and construct a template of spectral time series as a function of the light-curve-shape parameter, color stretch $s_{BV}$. Principal component analysis is applied to characterize the diversity of the spectral features and reduce data dimensionality to a smaller subspace. Gaussian process regression is then used to model the subspace dependence on phase and light-curve shape and the associated uncertainty. Our template is able to predict spectral variations that are correlated with $s_{BV}$, such as the hallmark NIR features: Mg II at early times and the $H$-band break after peak. Using this template reduces the systematic uncertainties in K-corrections by ~90% compared to those from the Hsiao template. These uncertainties, defined as the mean K-correction differences computed with the color-matched template and observed spectra, are on the level of $4\times10^{-4}$ mag on average. This template can serve as the baseline spectral energy distribution for light-curve fitters and can identify peculiar spectral features that might point to compelling physics. The results presented here will substantially improve future SN~Ia cosmological experiments, for both nearby and distant samples., Comment: 38 pages, 21 figures, accepted to APJ

Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf (WD) stars destabilized by mass accretion from a companion star, but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds or binary interaction prior to explosion, and the SN ejecta crashing into this nearby circumstellar material (CSM) should result in radio synchrotron emission. However, despite extensive efforts, no SN Ia has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate WD star. Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich CSM, as revealed by its spectral features, infrared emission and, for the first time in a SN Ia, a radio counterpart. Based on our modeling, we conclude the CSM likely originates from a single-degenerate (SD) binary system where a WD accretes material from a helium donor star, an often hypothesized formation channel for SNe Ia. We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems., Comment: 62 pages, 10 figures, 4 tables

The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable and transient radio sources on timescales from 5 s to$\sim\!5$yr. In this paper, we present the survey description, observation strategy and initial results from the VAST Phase I Pilot Survey. This pilot survey consists of$\sim\!162$h of observations conducted at a central frequency of 888 MHz between 2019 August and 2020 August, with a typical rms sensitivity of$0.24\ \mathrm{mJy\ beam}^{-1}$and angular resolution of$12-20$arcseconds. There are 113 fields, each of which was observed for 12 min integration time, with between 5 and 13 repeats, with cadences between 1 day and 8 months. The total area of the pilot survey footprint is 5 131 square degrees, covering six distinct regions of the sky. An initial search of two of these regions, totalling 1 646 square degrees, revealed 28 highly variable and/or transient sources. Seven of these are known pulsars, including the millisecond pulsar J2039–5617. Another seven are stars, four of which have no previously reported radio detection (SCR J0533–4257, LEHPM 2-783, UCAC3 89–412162 and 2MASS J22414436–6119311). Of the remaining 14 sources, two are active galactic nuclei, six are associated with galaxies and the other six have no multi-wavelength counterparts and are yet to be identified.

Fast Radio Burst (FRB) dispersion measures (DMs) record the presence of ionized baryons that are otherwise invisible to other techniques enabling resolution of the matter distribution in the cosmic web. In this work, we aim to estimate the contribution to FRB 180924 DM from foreground galactic halos. Localized by ASKAP to a massive galaxy, this sightline is notable for an estimated cosmic web contribution to the DM ($\rm DM_{cosmic} = 220~pc~cm^{-3}$), which is less than the average value at the host redshift ($\rm z = 0.3216$) estimated from the Macquart relation ($280~\rm pc~cm^{-3}$). In the favored models of the cosmic web, this suggests few intersections with foreground halos at small impact parameters ($\lesssim 100$ kpc). To test this hypothesis, we carried out spectroscopic observations of the field galaxies within $\sim$1' of the sightline with VLT/MUSE and Keck/LRIS. Furthermore, we developed a probabilistic methodology that leverages photometric redshifts derived from wide-field DES and WISE imaging. We conclude that there is no galactic halo that closely intersects the sightline and also that the net DM contribution from halos, $\rm DM_{halos}< 45~pc~cm^{-3}$ (95 % c.l.). This value is lower than the $\rm DM_{halos}$ estimated from an "average" sightline ($121~\rm pc~cm^{-3}$) using the Planck $\Lambda CDM$ model and the Aemulus halo mass function and reasonably explains its low $\rm DM_{cosmic}$ value. We conclude that FRB 180924 represents the predicted majority of sightlines in the universe with no proximate foreground galactic halos. Our framework lays the foundation for a comprehensive analysis of FRB fields in the near future., Comment: 10 pages, 6 figures, 1 extended, machine-readable table. See latex files for the full version of Table 1 (photom_tab_full.tex)

We present the results of ALMA band 3 observations of a nearby type Ic supernova (SN) 2020oi. Under the standard assumptions on the SN-circumstellar medium (CSM) interaction and the synchrotron emission, the data indicate that the CSM structure deviates from a smooth distribution expected from the steady-state mass loss in the very vicinity of the SN (~10^{15} cm), which is then connected to the outer smooth distribution (~10^{16} cm). This structure is further confirmed through the light curve modeling of the whole radio data set as combined with data at lower frequency previously reported. Being an explosion of a bare carbon-oxygen (C+O) star having a fast wind, we can trace the mass-loss history of the progenitor of SN 2020oi in the final year. The inferred non-smooth CSM distribution corresponds to fluctuations on the sub-year time scale in the mass-loss history toward the SN explosion. Our finding suggests that the pre-SN activity is likely driven by the accelerated change in the nuclear burning stage in the last moments just before the massive star's demise. The structure of the CSM derived in this study is beyond the applicability of the other methods at optical wavelengths, highlighting an importance and uniqueness of quick follow-up observations of SNe by ALMA and other radio facilities., Instituto de Astrofísica de La Plata

We present the Australian Square Kilometre Array Pathfinder (ASKAP) localization and follow-up observations of the host galaxy of the repeating fast radio burst (FRB) source, FRB20201124A, the fifth such extragalactic repeating FRB with an identified host. From spectroscopic observations using the 6.5-m MMT Observatory, we derive a redshift of $z=0.0979 \pm 0.0001$, a star formation rate inferred from H$\alpha$ emission of SFR(H$\alpha$) $\approx 2.1 M_{\odot}$ yr$^{-1}$, and a gas-phase metallicity of 12+log(O/H)$\approx 9.0$. By jointly modeling the 12-filter optical-mid-infrared (MIR) photometry and spectroscopy of the host, we infer a median stellar mass of $\approx 2 \times 10^{10} M_{\odot}$, internal dust extinction of $A_V\approx 1-1.5$ mag, and a mass-weighted stellar population age of $\approx 5-6$ Gyr. Connecting these data to the radio and X-ray observations, we cannot reconcile the broad-band behavior with strong AGN activity and instead attribute the dominant source of persistent radio emission to star formation, likely originating from the circumnuclear region of the host. The modeling also indicates a hot dust component contributing to the MIR luminosity at a level of $\approx 10-30\%$. We model the host galaxy's star formation and mass assembly histories, finding that the host assembled $>90\%$ of its mass by 1 Gyr ago and exhibited a fairly constant SFR for most of its existence, with no clear evidence of past star-burst activity., Comment: 18 pages, 5 figures, 5 tables. Added tables and updated to current literature. Accepted to ApJ Letters

We present high-cadence optical and ultraviolet light curves of the normal Type Ia supernova (SN) 2021aefx, which shows an early bump during the first two days of observation. This bump may be a signature of interaction between the exploding white dwarf and a nondegenerate binary companion, or it may be intrinsic to the white dwarf explosion mechanism. In the case of the former, the short duration of the bump implies a relatively compact main-sequence companion star, although this conclusion is viewing-angle dependent. Our best-fit companion-shocking and double-detonation models both overpredict the UV luminosity during the bump, and existing nickel-shell models do not match the strength and timescale of the bump. We also present nebular spectra of SN 2021aefx, which do not show the hydrogen or helium emission expected from a nondegenerate companion, as well as a radio nondetection that rules out all symbiotic progenitor systems and most accretion disk winds. Our analysis places strong but conflicting constraints on the progenitor of SN 2021aefx; no current model can explain all of our observations., Comment: updated to match accepted version

Acknowledgements. We thank the anonymous referee for useful comments. We thank Marco Fiaschi for carrying out some of the Asiago observations. EK is supported by the Turku Collegium of Science, Medicine and Technology. EK also acknowledge support from the Science and Technology Facilities Council (STFC; ST/P000312/1). ECK acknowledges support from the G.R.E.A.T. research environment and support from The Wenner-Gren Foundations. MF is supported by a Royal Society – Science Foundation Ireland University Research Fellowship. EC, LT, AP, and MT are partially supported by the PRIN-INAF 2017 with the project “Towards the SKA and CTA era: discovery, localization, and physics of transient objects”. HK was funded by the Academy of Finland projects 324504 and 328898. TWC acknowledges the EU Funding under Marie Skłodowska-Curie grant agreement No. 842471. LG was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-B-C21 within the European Funds for Regional Development (FEDER). MG is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. KM acknowledges support from EU H2020 ERC grant no. 758638. TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. MN is supported by a Royal Astronomical Society Research Fellowship. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 67.D-0438, 60.A-9475, 199.D-0143, and 1103.D-0328. Some of the observations reported in this paper were obtained with the Southern African Large Telescope (SALT) under programme 2018-1-DDT-003 (PI: Kankare). Polish participation in SALT is funded by grant No. MNiSW DIR/WK/2016/07. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. This work is partly based on the NUTS2 programme carried out at the NOT. NUTS2 is funded in part by the Instrument Center for Danish Astrophysics (IDA). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. This paper is also based on observations collected at the Copernico 1.82 m and Schmidt 67/92 Telescopes operated by INAF – Osservatorio Astronomico di Padova at Asiago, Italy. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). Observations were carried out under programme GS-2017A-C-1. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the DOE and NSF (USA), MISE (Spain), STFC (UK), HEFCE (UK), NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M University), CNPQ, FAPERJ, FINEP (Brazil), MINECO (Spain), DFG (Germany) and the collaborating institutions in the Dark Energy Survey, which are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMAT-Madrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Zürich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU München and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, OzDES Membership Consortium, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University. Based on observations obtained with the Samuel Oschin 48-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory (NOAO Prop. ID 2017A-0260; and PI: Soares-Santos), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work is based in part on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research has made use of NED which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We have made use of the Weizmann Interactive Supernova Data Repository (Yaron & Gal-Yam 2012, https://wiserep.weizmann.ac.il)., 1 iraf is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation., The fraction of core-collapse supernovae (CCSNe) occurring in the central regions of galaxies is not well constrained at present. This is partly because large-scale transient surveys operate at optical wavelengths, making it challenging to detect transient sources that occur in regions susceptible to high extinction factors. Here we present the discovery and follow-up observations of two CCSNe that occurred in the luminous infrared galaxy (LIRG) NGC 3256. The first, SN 2018ec, was discovered using the ESO HAWK-I/GRAAL adaptive optics seeing enhancer, and was classified as a Type Ic with a host galaxy extinction of AV = 2.1−0.1+0.3 mag. The second, AT 2018cux, was discovered during the course of follow-up observations of SN 2018ec, and is consistent with a subluminous Type IIP classification with an AV = 2.1 ± 0.4 mag of host extinction. A third CCSN, PSN J10275082−4354034 in NGC 3256, was previously reported in 2014, and we recovered the source in late-time archival Hubble Space Telescope imaging. Based on template light curve fitting, we favour a Type IIn classification for it with modest host galaxy extinction of AV = 0.3−0.3+0.4 mag. We also extend our study with follow-up data of the recent Type IIb SN 2019lqo and Type Ib SN 2020fkb that occurred in the LIRG system Arp 299 with host extinctions of AV = 2.1−0.3+0.1 and AV = 0.4−0.2+0.1 mag, respectively. Motivated by the above, we inspected, for the first time, a sample of 29 CCSNe located within a projected distance of 2.5 kpc from the host galaxy nuclei in a sample of 16 LIRGs. We find, if star formation within these galaxies is modelled assuming a global starburst episode and normal IMF, that there is evidence of a correlation between the starburst age and the CCSN subtype. We infer that the two subgroups of 14 H-poor (Type IIb/Ib/Ic/Ibn) and 15 H-rich (Type II/IIn) CCSNe have different underlying progenitor age distributions, with the H-poor progenitors being younger at 3σ significance. However, we note that the currently available sample sizes of CCSNe and host LIRGs are small, and the statistical comparisons between subgroups do not take into account possible systematic or model errors related to the estimated starburst ages., DOCTORADOBECAS CHILE/2017-72180113, Deutsches Elektronen-Synchrotron and Humboldt University, EU H2020 ERC 758638, IFAE Barcelona, IPAC, Instituto de Astrofisica de Canarias, KICP, MIFPA, Marie Skłodowska-Curie 839090,PGC2018-095317-B-C21, Max Planck Institute for Astronomy, Max Planck Institute for Extraterrestrial Physics, NOAO, National Central University of Taiwan, National Optical Astronomy Observatories, Science Foundation Ireland University, Turku Collegium of Science, Medicine and Technology, Weizmann Institute for Science, National Science Foundation NSF, U.S. Department of Energy USDOE, National Aeronautics and Space Administration AST-1238877,NNX08AR22G NASA, Gordon and Betty Moore Foundation NAS5-26555 GBMF, Merck Institute for Science Education MISE, University of Illinois at Urbana-Champaign UIUC, Stanford University SU, Argonne National Laboratory ANL, Lawrence Berkeley National Laboratory 2017A-0260 LBNL, University of Wisconsin-Milwaukee, Ohio State University OSU, California Institute of Technology CIT, University of Chicago, University of Michigan U-M, University of Washington UW, Johns Hopkins University JHU, Texas A and M University TAMU, University of Maryland UMD, University of Hawai'i UH, Los Alamos National Laboratory LANL, University of Portsmouth, Smithsonian Astrophysical Observatory SAO, National Centre for Supercomputing Applications NCSA, Horizon 2020 Framework Programme H2020, SLAC National Accelerator Laboratory SLAC, National Research Council NRC, Space Telescope Science Institute STScI, Center for Cosmology and Astroparticle Physics, Ohio State University CCAPP, Wenner-Gren Stiftelserna, Science and Technology Facilities Council ST/P000312/1 STFC, Royal Society, Royal Astronomical Society MNiSW DIR/WK/2016/07 RAS, University College London UCL, European Commission 842471 EC, University of Nottingham, University of Sussex AST-1440341, University of Edinburgh ED, Queen's University Belfast QUB, Durham University, Deutsche Forschungsgemeinschaft DFG, Suomen Akatemia 324504,328898, Comisión Nacional de Investigación Científica y Tecnológica CONICYT, Ministerio de Ciencia, Tecnología e Innovación Productiva MINCyT, Ministerio de Economía y Competitividad MINECO, Ministério da Ciência, Tecnologia e Inovação MCTI, Liverpool John Moores University LJMU, Max-Planck-Gesellschaft MPG, Narodowe Centrum Nauki 2014/14/A/ST9/00121 NCN, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro FAPERJ, Financiadora de Estudos e Projetos FINEP, European Regional Development Fund ERDF, Eötvös Loránd Tudományegyetem ELTE

We assemble a large set of 2-10 GHz radio flux density measurements and upper limits of 294 different supernovae (SNe), from the literature and our own and archival data. Only 31% of the SNe were detected. We characterize the SN lightcurves near the peak using a two-parameter model, with $t_{\rm pk}$ being the time to rise to a peak and $L_{\rm pk}$ the spectral luminosity at that peak. Over all SNe in our sample at $D, Accepted for publication in the Astrophysical Journal 15 Figures, 4 Tables; Full version of Table 1 in ancillary files. Minor revisions only from version 1

Fast Radio Bursts (FRBs) are extremely energetic pulses of millisecond duration and unknown origin. In order to understand the phenomenon that emits these pulses, targeted and untargeted searches have been performed for multi-wavelength counterparts, including the optical. The objective of this work is to search for optical transients at the position of 8 well-localized FRBs, after the arrival of the burst on different time-scales (typically at one day, several months, and one year after FRB detection) in order to compare with known transient optical light curves. We used the Las Cumbres Observatory Global Telescope Network (LCOGT), which allows us to promptly take images owing to its network of twenty-three telescopes working around the world. We used a template subtraction technique on all the images we collected at different epochs. We have divided the subtractions into two groups, in one group we use the image of the last epoch as a template and in the other group we use the image of the first epoch as a template. We have searched for bright optical transients at the localizations of the FRBs (, Accepted to Astronomy & Astrophysics on 27 June, 2021. 8 pages, 3 figures, 3 tables

We present observations and detailed characterizations of five new host galaxies of fast radio bursts (FRBs) discovered with the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to $\lesssim 1''$. Combining these galaxies with FRB hosts from the literature, we introduce criteria based on the probability of chance coincidence to define a sub-sample of 10 highly-confident associations (at $z=0.03-0.52$), three of which correspond to known repeating FRBs. Overall, the FRB host galaxies exhibit a broad, continuous range of color ($M_u-M_r = 0.9 - 2.0$), stellar mass ($M_\star = 10^{8} - 6\times 10^{10}\,M_{\odot}$), and star-formation rate (${\rm SFR} = 0.05 - 10\,M_{\odot}\,{\rm yr}^{-1}$) spanning the full parameter space occupied by $z99\%$ c.l.). We measure a median offset of 3.3 kpc from the FRB to the estimated center of the host galaxies and compare the host-burst offset distribution and other properties with the distributions of long- and short-duration gamma-ray bursts (LGRBs and SGRBs), core-collapse supernovae (CC-SNe), and Type Ia SNe. This analysis rules out galaxies hosting LGRBs (faint, star-forming galaxies) as common hosts for FRBs ($>95\%$ c.l.). Other transient channels (SGRBs, CC- and Type Ia SNe) have host galaxy properties and offsets consistent with the FRB distributions. All of the data and derived quantities are made publicly available on a dedicated website and repository., Accepted for publication in ApJ. All data are publicly available at https://frbhosts.org and https://github.com/FRBs/FRB. Version 2 of manuscript includes updated FRB uncertainty estimates

We present the discovery with Keck of the extremely infrared (IR) luminous transient AT 2017gbl, coincident with the Northern nucleus of the luminous infrared galaxy (LIRG) IRAS 23436+5257. Our extensive multiwavelength follow-up spans similar to 900 d, including photometry and spectroscopy in the optical and IR, and (very long baseline interferometry) radio and X-ray observations. Radiative transfer modelling of the host galaxy spectral energy distribution and long-term pre-outburst variability in the mid-IR indicate the presence of a hitherto undetected dust obscured active galactic nucleus (AGN). The optical and near-IR spectra show broad similar to 2000 km s(-1) hydrogen, He I, and OI emission features that decrease in flux over time. Radio imaging shows a fast evolving compact source of synchrotron emission spatially coincident with AT 2017gbl. We infer a lower limit for the radiated energy of 7.3 x 10(50) erg from the IR photometry. An extremely energetic supernova would satisfy this budget, but is ruled out by the radio counterpart evolution. Instead, we propose AT 2017gbl is related to an accretion event by the central supermassive black hole, where the spectral signatures originate in the AGN broad line region and the IR photometry is consistent with re-radiation by polar dust. Given the fast evolution of AT 2017gbl, we deem a tidal disruption event (TDE) of a star a more plausible scenario than a dramatic change in the AGN accretion rate. This makes AT 2017gbl the third TDE candidate to be hosted by a LIRG, in contrast to the so far considered TDE population discovered at optical wavelengths and hosted preferably by post-starburst galaxies., ECKacknowledges support from the Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT) research environment funded by Vetenskapsradet under project no. 2016-06012, financial support from the visitor and mobility program of the Finnish Centre for Astronomy with ESO (FINCA), funded by the Academy of Finland grant no. 306531, and support from The Wenner-Gren Foundations under project no. UPD2019-0070. TMR acknowledges the financial support of the Jenny and Antti Wihuri foundation and the Vilho, Yrjo and Kalle Vaisala Foundation of the Finnish Academy of Science and Letters. MPT acknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andaluc ' ia (SEV-2017-0709) and through grant PGC2018-098915-B-C21 (MCI/AEI/FEDER). CRC acknowledges support by the Chinese Academy of Sciences (CAS), through grant CAS16013 of the CAS South America Center for Astronomy (CASSACA) and Programa de Astronomia CONICYT, Chile. PGJ and GC acknowledge support from European Research Council Consolidator Grant 647208. MG is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. GEA is the recipient of an Australian Research Council Discovery Early Career Researcher Award (project DE180100346) and acknowledges partial support through the Australian Research Council's Discovery Projects funding scheme (project DP200102471). ST acknowledges financial support from the Russian Foundation for Basic Research project 1752-80139 BRICS-a. RMcD is the recipient of an Australian Research Council Future Fellowship Award (project number FT150100333). WL is supported by the David and Ellen Lee Fellowship at Caltech. The NOT Unbiased Transient Survey 2 (NUTS2) is funded in part by the Instrument Center for Danish Astronomy. Some of the data (PI: S. Ryder; program IDs Z229N2L, Z271N2L) presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authorswish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We thank the Mullard Radio Astronomy Observatory for carrying out the AMI-LA observations. Thiswork is based in part on observations (PIs: E. Kool, K. Maeda; program IDs GN-2017B-DD-2, GN-2018B-FT-109) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina), Ministerio da Ciencia, Tecnologia e Inovacao (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). The scientific results reported in this article are based in part on observations (PI: T. Heikkila; program ID 18208589) made by the Chandra X-ray Observatory, and this research has made use of the CIAO software package provided by the ChandraX-rayCenter (CXC). This article includes results based on observations made by the Neil Gehrels Swift observatory. The authors thank Chandra and Swift teams for the approval and rapid scheduling of our observations. This work is based in part on observations made with theWilliam Herschel Telescope (WHT). The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The ISIS and ACAM data were obtained as part of (17A)N4/N6, (18A)N4, and (18B)N5. This work is based in part on observations (PI: S. Mattila; program IDs 13226, 14054) made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication also makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of the National Aeronautics and Space Administration. This work is based in part on observations from programs RP028B and BP225 (PI: M. Perez-Torres) obtained with the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA), respectively. The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, theMax Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the MaxPlanck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.

More than three quarters of the baryonic content of the Universe resides in a highly diffuse state that is difficult to observe, with only a small fraction directly observed in galaxies and galaxy clusters. Censuses of the nearby Universe have used absorption line spectroscopy to observe these invisible baryons, but these measurements rely on large and uncertain corrections and are insensitive to the majority of the volume, and likely mass. Specifically, quasar spectroscopy is sensitive either to only the very trace amounts of Hydrogen that exists in the atomic state, or highly ionized and enriched gas in denser regions near galaxies. Sunyaev-Zel'dovich analyses provide evidence of some of the gas in filamentary structures and studies of X-ray emission are most sensitive to gas near galaxy clusters. Here we report the direct measurement of the baryon content of the Universe using the dispersion of a sample of localized fast radio bursts (FRBs), thus utilizing an effect that measures the electron column density along each sight line and accounts for every ionised baryon. We augment the sample of published arcsecond-localized FRBs with a further four new localizations to host galaxies which have measured redshifts of 0.291, 0.118, 0.378 and 0.522, completing a sample sufficiently large to account for dispersion variations along the line of sight and in the host galaxy environment to derive a cosmic baryon density of $\Omega_{b} = 0.051_{-0.025}^{+0.021} \, h_{70}^{-1}$ (95% confidence). This independent measurement is consistent with Cosmic Microwave Background and Big Bang Nucleosynthesis values., Comment: Published online in Nature 27 May, 2020

Classical novae are thermonuclear explosions that occur on the surfaces of white dwarf stars in interacting binary systems (Bode & Evans 2008). It has long been thought that the luminosity of classical novae is powered by continued nuclear burning on the surface of the white dwarf after the initial runaway (Gallaher & Starrfield 1978). However, recent observations of GeV $\gamma$-rays from classical novae have hinted that shocks internal to the nova ejecta may dominate the nova emission. Shocks have also been suggested to power the luminosity of events as diverse as stellar mergers (Metzger & Pejcha 2017), supernovae (Moriya et al. 2018), and tidal disruption events (Roth et al. 2016), but observational confirmation has been lacking. Here we report simultaneous space-based optical and $\gamma$-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands. The optical and $\gamma$-ray flares occur simultaneously, implying a common origin in shocks. During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock-powered. Furthermore, we detect concurrent but weak X-ray emission from deeply embedded shocks, confirming that the shock power does not appear in the X-ray band and supporting its emergence at longer wavelengths. Our data, spanning the spectrum from radio to $\gamma$-ray, provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients., Comment: 49 pages including supplementary information. Accepted and published in Nature Astronomy

Searches for optical transients are usually performed with a cadence of days to weeks, optimised for supernova discovery. The optical fast transient sky is still largely unexplored, with only a few surveys to date having placed meaningful constraints on the detection of extragalactic transients evolving at sub-hour timescales. Here, we present the results of deep searches for dim, minute-timescale extragalactic fast transients using the Dark Energy Camera, a core facility of our all-wavelength and all-messenger Deeper, Wider, Faster programme. We used continuous 20s exposures to systematically probe timescales down to 1.17 minutes at magnitude limits $g > 23$ (AB), detecting hundreds of transient and variable sources. Nine candidates passed our strict criteria on duration and non-stellarity, all of which could be classified as flare stars based on deep multi-band imaging. Searches for fast radio burst and gamma-ray counterparts during simultaneous multi-facility observations yielded no counterparts to the optical transients. Also, no long-term variability was detected with pre-imaging and follow-up observations using the SkyMapper optical telescope. We place upper limits for minute-timescale fast optical transient rates for a range of depths and timescales. Finally, we demonstrate that optical $g$-band light curve behaviour alone cannot discriminate between confirmed extragalactic fast transients such as prompt GRB flashes and Galactic stellar flares., Published in MNRAS

There have been a dramatic increase in the number of optical and radio transient surveys due to astronomical transients such as gravitational waves and gamma ray bursts, however, there have been a limited number of wide-field infrared surveys due to narrow field-of-view and high cost of infrared cameras, we present two new wide-field near-infrared fully automated surveyors; Palomar Gattini-IR and the Dynamic REd All-sky Monitoring Survey (DREAMS). Palomar Gattini-IR, a 25 square degree J-band imager that begun science operations at Palomar Observatory, USA in October 2018; we report on survey strategy as well as telescope and observatory operations and will also providing initial science results. DREAMS is a 3.75 square degree wide-field imager that is planned for Siding Spring Observatory, Australia; we report on the current optical and mechanical design and plans to achieve on-sky results in 2020. DREAMS is on-track to be one of the first astronomical telescopes to use an Indium Galium Arsenide (InGaAs) detector and we report initial on-sky testing results for the selected detector package. DREAMS is also well placed to take advantage and provide near-infrared follow-up of the LSST.

Authors: Koribalski, Bärbel S.; Staveley-Smith, L.; Westmeier, T.; Serra, P.; Spekkens, K.; Wong, O. I.; Lee-Waddell, K.; Lagos, C. D. P.; Obreschkow, D.; Ryan-Weber, E. V.; Zwaan, M.; Kilborn, V.; Bekiaris, G.; Bekki, K.; Bigiel, F.; Boselli, A.; Bosma, A.; Catinella, B.; Chauhan, G.; Cluver, M. E. Colless, M.; Courtois, H. M.; Crain, R. A.; de Blok, W. J. G.; Dénes, H.; Duffy, A. R.; Elagali, A.; Fluke, C. J.; For, B. -Q.; Heald, G.; Henning, P. A.; Hess, K. M.; Holwerda, B. W.; Howlett, C.; Jarrett, T.; Jones, D. H.; Jones, M. G.; Józsa, G. I. G.; Jurek, R.; Jütte, E.; Kamphuis, P.; Karachentsev, I.; Kerp, J.; Kleiner, D.; Kraan-Korteweg, R. C.; López-Sánchez, Á. R.; Madrid, J.; Meyer, M.; Mould, J.; Murugeshan, C.; Norris, R. P.; Oh, S. -H.; Oosterloo, T. A.; Popping, A.; Putman, M.; Reynolds, T. N.; Rhee, J.; Robotham, A. S. G.; Ryder, S.; Schröder, A. C.; Shao, Li; Stevens, A. R. H.; Taylor, E. N.; van der Hulst, J. M.; Verdes-Montenegro, L.; Wakker, B. P.; Wang, J.; Whiting, M.; Winkel, B.; Wolf, C., The Widefield ASKAP L-band Legacy All-sky Blind surveY (wallaby) is a next-generation survey of neutral hydrogen (H i) in the Local Universe. It uses the widefield, high-resolution capability of the Australian Square Kilometer Array Pathfinder (ASKAP), a radio interferometer consisting of 36 × 12 -m dishes equipped with Phased-Array Feeds (PAFs), located in an extremely radio-quiet zone in Western Australia. wallaby aims to survey three-quarters of the sky (− 90 < δ< + 30 ) to a redshift of z≲ 0.26 , and generate spectral line image cubes at ∼30 arcsec resolution and ∼1.6 mJy beam per 4 km s channel sensitivity. ASKAP’s instantaneous field of view at 1.4 GHz, delivered by the PAF’s 36 beams, is about 30 sq deg. At an integrated signal-to-noise ratio of five, wallaby is expected to detect around half a million galaxies with a mean redshift of z∼ 0.05 (∼200 Mpc). The scientific goals of wallaby include: (a) a census of gas-rich galaxies in the vicinity of the Local Group; (b) a study of the H i properties of galaxies, groups and clusters, in particular the influence of the environment on galaxy evolution; and (c) the refinement of cosmological parameters using the spatial and redshift distribution of low-bias gas-rich galaxies. For context we provide an overview of recent and planned large-scale H i surveys. Combined with existing and new multi-wavelength sky surveys, wallaby will enable an exciting new generation of panchromatic studies of the Local Universe. — First results from the wallaby pilot survey are revealed, with initial data products publicly available in the CSIRO ASKAP Science Data Archive (CASDA). © 2020, Springer Nature B.V., The Australian SKA Pathfinder (ASKAP) is part of the Australia Telescope National Facility (ATNF) which is managed by CSIRO. Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy (NCRIS). ASKAP uses the resources of the Pawsey Supercomputing Centre. Establishment of ASKAP, the Murchison Radio-astronomy Observatory (MRO) and the Pawsey Supercomputing Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. We acknowledge the Wajarri Yamatji as the traditional owners of the Observatory site. FB and DK acknowledge funding from the European Union's Horizon 2020 research and innovation programme; grant agreement No 726384 (FB) and No 679627 (DK). MEC is a recipient of an Australian Research Council Future Fellowship (project number FT170100273) funded by the Australian Government. RKK acknowledges the South African Research Chairs Initiative of the Department of Science and Innovation. RKK and GIGJ acknowledge the South African National Research Foundation for their support. MGJ and LVM acknowledge support from the grants AYA2015-65973-C3-1-R (MINECO/FEDER, UE) and RTI2018-096228-B-C31 (MICIU/FEDER, EU), as well as from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-20170709). MGJ is supported by a Juan de la Cierva formacion fellowship (FJCI-2016-29685). PK is partially supported by the BMBF project 05A17PC2 for D-MeerKAT. DO is a recipient of an Australian Research Council Future Fellowship (FT190100083) funded by the Australian Government. KS acknowledges support from the Natural Sciences and Engineering Research Council of Canada (NSERC). JMvdH acknowledges support from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement nr. 291531. Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013.

Fast radio bursts (FRBs) are millisecond-scale radio pulses, which originate in distant galaxies and are produced by unknown sources. The mystery remains partially because of the typical difficulty in localising FRBs to host galaxies. Accurate localisations delivered by the Commensal Real-time ASKAP Fast Transients (CRAFT) survey now provide an opportunity to study the host galaxies and potential transient counterparts of FRBs at a large range of wavelengths. In this work, we investigate whether the first three FRBs accurately localised by CRAFT have supernova-like transient counterparts. We obtained two sets of imaging epochs with the Very Large Telescope for three host galaxies, one soon after the burst detection and one several months later. After subtracting these images no optical counterparts were identified in the associated FRB host galaxies, so we instead place limits on the brightness of any potential optical transients. A Monte Carlo approach, in which supernova light curves were modelled and their base properties randomised, was used to estimate the probability of a supernova associated with each FRB going undetected. We conclude that Type Ia and IIn supernovae are unlikely to accompany every apparently non-repeating FRB., Comment: 7 pages, 3 figures. Accepted to Astronomy & Astrophysics on 03 June 2020

We report deep radio observations of nearby Type Ia supernovae (SNe Ia) with the electronic Multi-Element Radio Linked Interferometer Network and the Australia Telescope Compact Array. No detections were made. With standard assumptions for the energy densities of relativistic electrons going into a power-law energy distribution and the magnetic field strength ( e = B = 0.1), we arrive at upper limits on mass-loss rate for the progenitor system of SN 2013dy (SN 2016coj, SN 2018gv, SN 2018pv, SN 2019np) of, where v w is the wind speed of the mass loss. To SN 2016coj, SN 2018gv, SN 2018pv, and SN 2019np we add radio data for 17 other nearby SNe Ia and model their nondetections. With the same model as described, all 21 SNe Ia have. We compare those limits with the expected mass-loss rates in different single-degenerate progenitor scenarios. We also discuss how information on e and B can be obtained from late observations of SNe Ia and the youngest SN Ia remnant detected in radio, G1.9+0.3, as well as stripped-envelope core-collapse SNe. We highlight SN 2011dh and argue for e ≈ 0.1 and B ≈ 0.0033. Finally, we discuss strategies to observe at radio frequencies to maximize the chance of detection, given the time since explosion, the distance to the SN, and the telescope sensitivity. © 2020. The American Astronomical Society. All rights reserved., We thank Subo Dong for sharing data for SN.2018gv and SN 2018pv prior to publication, Stephen Reynolds for discussions and comments on an early version of the manuscript, and Nancy Elias-Rosa for discussions on SN.2019np. P. L. acknowledges support from the Swedish Research Council, and M.P.T. acknowledges financial support from the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and through the MINECO grants AYA2012-38491-C02-02 and AYA2015-63939-C2-1-P. J.M. acknowledges financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and from the grant RTI2018-096228-B-C31 (MICIU/FEDER, EU). The research leading to these results has received funding from the European Commission Horizon 2020 Research and Innovation Programme under grant agreement No. 730562 (RadioNet). The electronic Multi-Element Radio Linked Interferometer Network (e-MERLIN) is the UK's facility for high-resolution radio astronomy observations, operated by the University of Manchester for the Science and Technology Facilities Council (STFC). The Australia Telescope Compact Array (ATCA) is part of the Australia Telescope National Facility, which is funded by the Australian Government for operation as a National Facility managed by CSIRO. The ATCA data reported here were obtained under program C1303 (P.I. P. Lundqvist). This research has made use of the NASA Astrophysics Data System (ADS) Bibliographic Services and 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 present Hubble Space Telescope (HST/WFC3) ultraviolet and infrared observations of eight fast radio burst (FRB) host galaxies with sub-arcsecond localizations, including the hosts of three known repeating FRBs. We quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding that they occur at moderate host normalized-offsets of 1.4 $r_e$ ([0.6,2.1] $r_e$; 68% interval), occur on fainter regions of their hosts in terms of IR light, but overall trace the radial distribution of IR light in their galaxies. The FRBs in our tested distribution do not clearly trace the distributions of any other transient population with known progenitors, and are statistically distinct from the locations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further find that most FRBs are not in regions of elevated local star formation rate and stellar mass surface densities in comparison to the mean global values of their hosts. We also place upper limits to the IR flux at the FRB positions of $m_{\rm IR}\gtrsim\!24.8-27.6$~AB~mag, constraining both satellite and background galaxies to luminosities well below the host luminosity of FRB121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR light, and that the positions of all well-localized FRBs located in such hosts are consistent with their spiral arms, although not on their brightest regions. Our results do not strongly support the primary progenitor channel of FRBs being connected either with the most massive (stripped-envelope) stars, or with events which require kicks and long delay times (neutron star mergers)., 21 pages, 9 figures, Accepted for publication in ApJ

Fast Radio Bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Non-repeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single pulse FRB 180924 to a position 4 kpc from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web., Published online in Science 27 June 2019

We present the discovery and the photometric and spectroscopic study of H-rich Type II supernova (SN) KSP-SN-2016kf (SN2017it) observed in the KMTNet Supernova Program in the outskirts of a small irregular galaxy at $z\simeq0.043$ within a day from the explosion. Our high-cadence, multi-color ($BVI$) light curves of the SN show that it has a very long rise time ($t_\text{rise}\simeq 20$ days in $V$ band), a moderately luminous peak ($M_V\simeq -$17.6 mag), a notably luminous and flat plateau ($M_V\simeq -$17.4 mag and decay slope $s\simeq0.53$ mag per 100 days), and an exceptionally bright radioactive tail. Using the color-dependent bolometric correction to the light curves, we estimate the $^{56}$Ni mass powering the observed radioactive tail to be $0.10\pm0.01$ M$_\odot$, making it a H-rich Type II SN with one of the largest $^{56}$Ni masses observed to date. The results of our hydrodynamic simulations of the light curves constrain the mass and radius of the progenitor at the explosion to be $\sim$15 M$_\odot$ (evolved from a star with an initial mass of $\sim$ 18.8 M$_\odot$) and $\sim1040$ R$_\odot$, respectively, with the SN explosion energy of $\sim 1.3\times 10^{51}$ erg s$^{-1}$. The above-average mass of the KSP-SN-2016kf progenitor, together with its low metallicity $ Z/Z_\odot \simeq0.1-0.4$ obtained from spectroscopic analysis, is indicative of a link between the explosion of high-mass red supergiants and their low-metallicity environment. The early part of the observed light curves shows the presence of excess emission above what is predicted in model calculations, suggesting there is interaction between the ejecta and circumstellar material. We further discuss the implications of the high progenitor initial mass and low-metallicity environment of KSP-SN-2016kf on our understanding of the origin of Type II SNe., 18 pages, 12 figures, accepted for publication in ApJ

Given the limited availability of direct evidence (pre-explosion observations) for supernova (SN) progenitors, the location of supernovae (SNe) within their host galaxies can be used to set limits on one of their most fundamental characteristics, their initial progenitor mass. We present our constraints on SN progenitors derived by comparing the radial distributions of 80 SNe in the SINGG and SUNGG surveys to the R-band, Halpha, and UV light distributions of the 55 host galaxies. The strong correlation of Type Ia SNe with R-band light is consistent with models containing only low mass progenitors, reflecting earlier findings. When we limit the analysis of Type II SNe to apertures containing 90 per cent of the total flux, the radial distribution of these SNe best traces far ultraviolet (FUV) emission, consistent with recent direct detections indicating Type II SNe have moderately massive red supergiant progenitors. Stripped Envelope (SE) SNe have the strongest correlation with Halpha fluxes, indicative of very massive progenitors (M* > 20 M_solar). This result contradicts a small, but growing, number of direct detections of SE SN progenitors indicating they are moderately massive binary systems. Our result is consistent, however, with a recent population analysis suggesting binary SE SN progenitor masses are regularly underestimated. SE SNe are centralised with respect to Type II SNe and there are no SE SNe recorded beyond half the maximum disc radius in the optical and one third the disc radius in the ultraviolet. The absence of SE SNe beyond these distances is consistent with reduced massive star formation efficiencies in the outskirts of the host galaxies., 17 pages

Present-day galaxies are surrounded by cool and enriched halo gas extending to hundreds of kiloparsecs. This halo gas is thought to be the dominant reservoir of material available to fuel future star formation, but direct constraints on its mass and physical properties have been difficult to obtain. We report the detection of a fast radio burst (FRB 181112) with arcsecond precision, which passes through the halo of a foreground galaxy. Analysis of the burst shows the halo gas has low net magnetization and turbulence. Our results imply predominantly diffuse gas in massive galactic halos, even those hosting active supermassive black holes, contrary to some previous results., Comment: Published in Science on 2019 September 26; Main (3 figures; 1 Table) + Supp (12 figures; 7 Tables)

We report the detection of near-infrared (NIR) [Fe II] (1.644 $\mu$m) and H$_{2}$ 1-0 S(1) (2.122 $\mu$m) line features associated with Galactic supernova remnants (SNRs) in the first quadrant using two narrowband imaging surveys, UWIFE and UWISH2. Among the total of 79 SNRs fully covered by both surveys, we found 19 [Fe II]-emitting and 19 H$_{2}$-emitting SNRs, giving a detection rate of 24% for each. Eleven SNRs show both emission features. The detection rate of [Fe II] and H$_{2}$ peaks at the Galactic longitude ($l$) of $40^{\circ}$-$50^{\circ}$ and $30^{\circ}$-$40^{\circ}$, respectively, and gradually decreases toward smaller/larger $l$. Five out of the eleven SNRs emitting both emission lines clearly show an "[Fe II]-H$_{2}$ reversal," where H$_{2}$ emission features are found outside the SNR boundary in [Fe II] emission. Our NIR spectroscopy shows that the H$_{2}$ emission originates from collisionally excited H$_{2}$ gas. The brightest SNR in both [Fe II] and H$_{2}$ emissions is W49B, contributing more than 70% and 50% of the total [Fe II] 1.644 $\mu$m ($2.0 \times 10^4$ L$_{\odot}$) and H$_{2}$ 2.122 $\mu$m ($1.2 \times 10^3$ L$_{\odot}$) luminosities of the detected SNRs. The total [Fe II] 1.644 $\mu$m luminosity of our Galaxy is a few times smaller than that expected from the SN rate using the correlation found in nearby starburst galaxies. We discuss possible explanations for this., Comment: 45 pages, 11 figures, 6 tables; accepted in AJ on 2019 Jan. 26

In luminous and ultraluminous infrared galaxies (U/LIRGs), the infall of gas into the central regions strongly enhances the star formation rate (SFR), especially within the nuclear regions which have also large amounts of interstellar dust. Within these regions SFRs of several tens to hundreds of solar masses per year ought to give rise to core-collapse supernova (SN) rates up to 1-2 SNe every year per galaxy. However, the current SN surveys, almost exclusively being ground-based seeing-limited and working at optical wavelengths, have been blinded by the interstellar dust and contrast issues therein. Thus the properties and rates of SNe in the nuclear environments of the most prolific SN factories in the Universe have remained largely unexplored. Here, we present results from high angular resolution observations of nearby LIRGs at infrared and radio wavelengths much less affected by the effects of extinction and lack of resolution hampering the optical searches.