| 1. |
- Bellm, Eric C., et al.
(author)
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The Zwicky Transient Facility : System Overview, Performance, and First Results
- 2019
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In: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
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Journal article (peer-reviewed)abstract
- The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg(2) field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope.
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| 2. |
- Ade, Peter, et al.
(author)
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The Simons Observatory : science goals and forecasts
- 2019
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :2
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Journal article (peer-reviewed)abstract
- The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial con figuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping approximate to 10% of the sky to a white noise level of 2 mu K-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of sigma(r) = 0.003. The large aperture telescope will map approximate to 40% of the sky at arcminute angular resolution to an expected white noise level of 6 mu K-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.
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| 3. |
- Coughlin, Michael W., et al.
(author)
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GROWTH on S190425z : Searching Thousands of Square Degrees to Identify an Optical or Infrared Counterpart to a Binary Neutron Star Merger with the Zwicky Transient Facility and Palomar Gattini-IR
- 2019
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 885:1
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Journal article (peer-reviewed)abstract
- The third observing run by LVC has brought the discovery of many compact binary coalescences. Following the detection of the first binary neutron star merger in this run (LIGO/Virgo S190425z), we performed a dedicated follow-up campaign with the Zwicky Transient Facility (ZTF) and Palomar Gattini-IR telescopes. The initial skymap of this single-detector gravitational wave (GW) trigger spanned most of the sky observable from Palomar Observatory. Covering 8000 deg(2) of the initial skymap over the next two nights, corresponding to 46% integrated probability, ZTF system achieved a depth of 21 m(AB) in g- and r-bands. Palomar Gattini-IR covered 2200 square degrees in J-band to a depth of 15.5 mag, including 32% integrated probability based on the initial skymap. The revised skymap issued the following day reduced these numbers to 21% for the ZTF and 19% for Palomar Gattini-IR. We narrowed 338,646 ZTF transient ?alerts? over the first two nights of observations to 15 candidate counterparts. Two candidates, ZTF19aarykkb and ZTF19aarzaod, were particularly compelling given that their location, distance, and age were consistent with the GW event, and their early optical light curves were photometrically consistent with that of kilonovae. These two candidates were spectroscopically classified as young core-collapse supernovae. The remaining candidates were ruled out as supernovae. Palomar Gattini-IR did not identify any viable candidates with multiple detections only after merger time. We demonstrate that even with single-detector GW events localized to thousands of square degrees, systematic kilonova discovery is feasible.
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| 4. |
- Stein, Robert, et al.
(author)
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A tidal disruption event coincident with a high-energy neutrino
- 2021
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In: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; :5, s. 510-518
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Journal article (peer-reviewed)abstract
- Cosmic neutrinos provide a unique window into the otherwise hidden mechanism of particle acceleration in astrophysical objects. The IceCube Collaboration recently reported the likely association of one high-energy neutrino with a flare from the relativistic jet of an active galaxy pointed towards the Earth. However a combined analysis of many similar active galaxies revealed no excess from the broader population, leaving the vast majority of the cosmic neutrino flux unexplained. Here we present the likely association of a radio-emitting tidal disruption event, AT2019dsg, with a second high-energy neutrino. AT2019dsg was identified as part of our systematic search for optical counterparts to high-energy neutrinos with the Zwicky Transient Facility. The probability of finding any coincident radio-emitting tidal disruption event by chance is 0.5%, while the probability of finding one as bright in bolometric energy flux as AT2019dsg is 0.2%. Our electromagnetic observations can be explained through a multizone model, with radio analysis revealing a central engine, embedded in a UV photosphere, that powers an extended synchrotron-emitting outflow. This provides an ideal site for petaelectronvolt neutrino production. Assuming that the association is genuine, our observations suggest that tidal disruption events with mildly relativistic outflows contribute to the cosmic neutrino flux. The tidal disruption event AT2019dsg is probably associated with a high-energy neutrino, suggesting that such events can contribute to the cosmic neutrino flux. The electromagnetic emission is explained in terms of a central engine, a photosphere and an extended synchrotron-emitting outflow.
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| 5. |
- Coughlin, Michael W., et al.
(author)
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2900 Square Degree Search for the Optical Counterpart of Short Gamma-Ray Burst GRB 180523B with the Zwicky Transient Facility
- 2019
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In: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:998
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Journal article (peer-reviewed)abstract
- There is significant interest in the models for production of short gamma-ray bursts (GRBs). Until now, the number of known short GRBs with multi-wavelength afterglows has been small. While the Fermi GRB Monitor detects many GRBs relative to the Neil Gehrels Swift Observatory, the large localization regions makes the search for counterparts difficult. With the Zwicky Transient Facility (ZTF) recently achieving first light, it is now fruitful to use its combination of depth (m(AB) similar to 20.6), field of view (approximate to 47 square degrees), and survey cadence (every similar to 3 days) to perform Target of Opportunity observations. We demonstrate this capability on GRB 180523B, which was recently announced by the Fermi GRB Monitor as a short GRB. ZTF imaged approximate to 2900 square degrees of the localization region, resulting in the coverage of 61.6% of the enclosed probability over two nights to a depth of m(AB) similar to 20.5. We characterized 14 previously unidentified transients, and none were found to be consistent with a short GRB counterpart. This search with the ZTF shows it is an efficient camera for searching for coarsely localized short GRB and gravitational-wave counterparts, allowing for a sensitive search with minimal interruption to its nominal cadence.
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| 6. |
- Kasliwal, Mansi M., et al.
(author)
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Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
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Journal article (peer-reviewed)abstract
- We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg(2), a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10(-25) yr(-1). The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than -16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day(-1) (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than -16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than <57% (<89%) of putative kilonovae could be brighter than -16.6 mag assuming flat evolution (fading by 1 mag day(-1)) at the 90% confidence level. If we further take into account the online terrestrial probability for each GW trigger, we find that no more than <68% of putative kilonovae could be brighter than -16.6 mag. Comparing to model grids, we find that some kilonovae must have M-ej M, X-lan > 10(-4), or > 30 degrees to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of -16 mag would constrain the maximum fraction of bright kilonovae to <25%.
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| 7. |
- Campbell, Rachel, et al.
(author)
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Measure of Ovarian Symptoms and Treatment concerns (MOST) indexes and their associations with health-related quality of life in recurrent ovarian cancer
- 2022
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In: Gynecologic Oncology. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0090-8258 .- 1095-6859. ; 166:2, s. 254-262
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Journal article (peer-reviewed)abstract
- Purpose. The Measure of Ovarian Symptoms and Treatment (MOST) concerns is a validated patient-reported symptom assessment tool for assessing symptom benefit and adverse effects of palliative chemotherapy in women with recurrent ovarian cancer (ROC). We aimed to examine (i) how symptoms within MOST symptom indexes track together (i.e. co-occur) and (ii) the association between MOST symptom indexes and key aspects of health-related quality of life (HRQL). Method. A prospective cohort of women with ROC completed the MOST-T35, EORTC QLQ-C30 and EORTC QLQ-OV28 at baseline and before each cycle of chemotherapy. Analyses were conducted on baseline and end -of-treatment data. Exploratory factor analysis and hierarchical cluster analysis identified groups of co-occurring symptoms. Path models examined associations between MOST symptom indexes and HRQL. Results. Data from 762 women at baseline and 681 at treatment-end who completed all 22 symptom-specific MOST items and at least one HRQL measure were analysed. Four symptom clusters emerged at baseline and treatment-end: abdominal symptoms, symptoms associated with peripheral neuropathy, nausea and vomiting, and psychological symptoms. Psychological symptoms (MOST-Psych) and symptoms due to disease (ovarian cancer) or treatment (MOST-DorT) were associated with poorer scores on QLQ-C30 and OV28 functioning do-mains and worse overall health at both time points. Conclusion. Four MOST symptom clusters were consistent across statistical methods and time points. These findings suggest that routine standardized assessment of psychological and physical symptoms in clinical prac-tice with MOST plus appropriate symptom management referral pathways is an intervention for improving HRQL that warrants further research. (c) 2022 Elsevier Inc. All rights reserved.
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| 8. |
- Jencson, Jacob E., et al.
(author)
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Discovery of an Intermediate-luminosity Red Transient in M51 and Its Likely Dust-obscured, Infrared-variable Progenitor
- 2019
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 880:2
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Journal article (peer-reviewed)abstract
- We present the discovery of an optical transient (OT) in Messier. 51, designated M51 OT2019-1 (also ZTF 19aadyppr, AT 2019abn, ATLAS19bz1), by the Zwicky Transient Facility (ZTF). The OT rose over 15. days to an observed luminosity of M-r = -13 (nu L-nu = 9 x 10(6) L-circle dot), in the luminosity gap between novae and typical supernovae (SNe). Spectra during the outburst show a red continuum, Balmer emission with a velocity width of approximate to 400 km s(-1), Ca II and [Ca II] emission, and absorption features characteristic of an F-type supergiant. The spectra and multiband light curves are similar to the so-called SN impostors and intermediate-luminosity red transients (ILRTs). We directly identify the likely progenitor in archival Spitzer Space Telescope imaging with a 4.5 mu m luminosity of M-[4.5] approximate to -12.2 mag and a [3.6]-[4.5] color redder than 0.74 mag, similar to those of the prototype ILRTs SN 2008S and NGC 300 OT2008-1. Intensive monitoring of M51 with Spitzer further reveals evidence for variability of the progenitor candidate at [ 4.5] in the years before the OT. The progenitor is not detected in pre-outburst Hubble Space Telescope optical and near-IR images. The optical colors during outburst combined with spectroscopic temperature constraints imply a higher reddening of E(B - V) approximate to 0.7 mag and higher intrinsic luminosity of M-r approximate to -14.9 mag (nu L-nu = 5.3 x 10(7) L-circle dot) near peak than seen in previous ILRT candidates. Moreover, the extinction estimate is higher on the rise than on the plateau, suggestive of an extended phase of circumstellar dust destruction. These results, enabled by the early discovery of M51. OT2019-1 and extensive pre-outburst archival coverage, offer new clues about the debated origins of ILRTs and may challenge the hypothesis that they arise from the electron-capture induced collapse of extreme asymptotic giant branch stars.
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| 9. |
- King, Madeleine T., et al.
(author)
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Measuring what matters MOST: validation of the Measure of Ovarian Symptoms and Treatment, a patient-reported outcome measure of symptom burden and impact of chemotherapy in recurrent ovarian cancer
- 2018
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In: Quality of Life Research. - : SPRINGER. - 0962-9343 .- 1573-2649. ; 27:1, s. 59-74
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Journal article (peer-reviewed)abstract
- Gynecologic Cancer Intergroup Symptom Benefit Study (GCIG-SBS) Stage 2 aimed to review, revise, and validate a patient-reported outcome measure (PROM), the Measure of Ovarian Symptoms and Treatment concerns (MOST), developed in GCIG-SBS Stage 1 (MOSTv1, 35 items), and document recurrent ovarian cancer (ROC) symptom burden and benefit. GCIG-SBS Stage 2 recruited patients with platinum-resistant/refractory ROC (PRR-ROC) or potentially platinum-sensitive ROC with aeamp;lt;yenamp;gt; 3 lines of prior chemotherapy (PPS-ROC aeamp;lt;yenamp;gt; 3). Patients completed MOSTv1, QLQ-C30, QLQ-OV28, and FACT-O/FOSI at baseline and before cycle 3 of chemotherapy (pre-C3), and global assessments of change (MOST-Change) pre-C3. Clinicians rated patients cancer-related symptoms, performance status, and adverse events. Convergent and divergent validity (Spearmans correlations), discriminative validity (effect sizes between groups classified by clinician-rated characteristics), and responsiveness (paired t tests in patients expected to experience clinically meaningful change) were assessed. Of 948 recruits, 903 completed PROMs at baseline and 685 pre-C3. Baseline symptom burden was substantial for PRR-ROC and PPS-ROC aeamp;lt;yenamp;gt; 3. MOSTv2 has 24 items and five multi-item scales: abdominal symptoms (MOST-Abdo), disease or treatment-related symptoms (MOST-DorT), chemotherapy-related symptoms (MOST-Chemo), psychological symptoms (MOST-Psych), and MOST-Well-being. Correlations confirmed concurrent and divergent validity. Discriminative validity was confirmed by effect sizes that conformed with a priori hypotheses. MOST-Abdo was responsive to improvements in abdominal symptoms and MOST-Chemo detected the adverse effects of chemotherapy. The MOSTv2 validly quantifies patient-reported symptom burden, adverse effects, and symptom benefit in ROC, and as such is fit-for-purpose for clinical trials of palliative chemotherapy in ROC. Further research is required to assess test-retest reliability.
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| 10. |
- Lee, Yeh Chen, et al.
(author)
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Symptom burden and quality of life with chemotherapy for recurrent ovarian cancer : the Gynecologic Cancer InterGroup-Symptom Benefit Study
- 2022
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In: International Journal of Gynecological Cancer. - : BMJ Publishing Group. - 1048-891X .- 1525-1438. ; 32:6, s. 761-768
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Journal article (peer-reviewed)abstract
- Objective The Gynecologic Cancer InterGroup (GCIG)-Symptom Benefit Study was designed to evaluate the effects of chemotherapy on symptoms and health-related quality of life (HRQL) in women having chemotherapy for platinum resistant/refractory recurrent ovarian cancer (PRR-ROC) and potentially platinum sensitive with >= 3 lines of chemotherapy (PPS-ROC >= 3). Methods Participants completed the Measure of Ovarian Cancer Symptoms and Treatment (MOST) and European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire QLQ-C30 questionnaires at baseline and every 3-4 weeks until progression. Participants were classified symptomatic if they rated >= 4 of 10 in at least one-third of symptoms in the MOST index. Improvement in MOST was defined as two consecutive scores of <= 3 in at least half of the symptomatic items at baseline. Improvement in HRQL was defined as two consecutive scores >= 10 points above baseline in the QLQ-C30 summary score scale (range 0-100). Results Of 948 participants enrolled, 910 (96%) completed baseline questionnaires: 546 with PRR-ROC and 364 with PPS-ROC >= 3. The proportions of participants symptomatic at baseline as per MOST indexes were: abdominal 54%, psychological 53%, and disease- or treatment-related 35%. Improvement was reported in MOST indexes: abdominal 40%, psychological 35%, and disease- or treatment-related 38%. Median time to improvement in abdominal symptoms occurred earlier for PRR-ROC than for PPS-ROC >= 3 (4 vs 6 weeks, p=0.044); median duration of improvement was also similar (9.0 vs 11.7 weeks, p=0.65). Progression-free survival was longer among those with improvement in abdominal symptoms than in those without (median 7.2 vs 2.5 months, p<0.0001). Improvements in HRQL were reported by 77/448 (17%) with PRR-ROC and 61/301 (20%) with PPS-ROC >= 3 (p=0.29), and 102/481 (21%) of those with abdominal symptoms at baseline. Conclusion Over 50% of participants reported abdominal and psychological symptoms at baseline. Of those, 40% reported an improvement within 2 months of starting chemotherapy. Approximately one in six participants reported an improvement in HRQL. Symptom monitoring and supportive care is important as chemotherapy palliated less than half of symptomatic participants.
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| 11. |
- Roncolato, Felicia T., et al.
(author)
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Reducing Uncertainty: Predictors of Stopping Chemotherapy Early and Shortened Survival Time in Platinum Resistant/Refractory Ovarian Cancer-The GCIG Symptom Benefit Study
- 2017
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In: The Oncologist. - : WILEY. - 1083-7159 .- 1549-490X. ; 22:9, s. 1117-1124
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Journal article (peer-reviewed)abstract
- Background. Clinicians and patients often overestimate the benefits of chemotherapy, and overall survival (OS), in platinum resistant/refractory ovarian cancer (PRROC). This study sought to determine aspects of health-related quality of life and clinicopathological characteristics before starting chemotherapy that were associated with stopping chemotherapy early, shortened survival, and death within 30 days of chemotherapy. Materials and Methods. This study enrolled women with PRROC before starting palliative chemotherapy. Health-related quality of life was measured with EORTC QLQ-C30/QLQ-OV28. Chemotherapy stopped within 8 weeks of starting was defined as stopping early. Logistic regression was used to assess univariable and multivariable associations with stopping chemotherapy early and death within 30 days of chemotherapy; Cox proportional hazards regression was used to assess associations with progression-free and OS. Results. Low baseline global health status (GHS), role function (RF), physical function (PF), and high abdominal/gastrointestinal symptom (AGIS) were associated with stopping chemotherapy early (all pamp;lt;.007); low PF and RF remained significant after adjusting for clinicopathological factors (both pamp;lt;.0401). Most who stopped chemotherapy early had Eastern Cooperative Oncology Group Performance Score 0-1 at baseline (79%); PF, RF, and GHS remained independently significant predictors of stopping chemotherapy early in this subgroup. Death within 30 days of chemotherapy occurred in 14%. Low-GHS, RF, and PF remained significantly associated with death within 30 days of chemotherapy after adjusting for clinicopathological factors (all pamp;lt;.012). Conclusion. Women with low GHS, RF, or PF before starting chemotherapy were more likely to stop chemotherapy early, with short OS. Self-ratings of GHS, RF, and PF could improve patient-clinician communication regarding prognosis and help decision-making in women considering chemotherapy for PRROC.
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| 12. |
- Soumagnac, Maayane T., et al.
(author)
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Early Ultraviolet Observations of Type IIn Supernovae Constrain the Asphericity of Their Circumstellar Material
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 899:1
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Journal article (peer-reviewed)abstract
- We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common-consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events.
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| 13. |
- van Velzen, Sjoert, et al.
(author)
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Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations : Entering a New Era of Population Studies
- 2021
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 908:1
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Journal article (peer-reviewed)abstract
- While tidal disruption events (TDEs) have long been heralded as laboratories for the study of quiescent black holes, the small number of known TDEs and uncertainties in their emission mechanism have hindered progress toward this promise. Here we present 17 new TDEs that have been detected recently by the Zwicky Transient Facility along with Swift UV and X-ray follow-up observations. Our homogeneous analysis of the optical/UV light curves, including 22 previously known TDEs from the literature, reveals a clean separation of light-curve properties with spectroscopic class. The TDEs with Bowen fluorescence features in their optical spectra have smaller blackbody radii, lower optical luminosities, and higher disruption rates compared to the rest of the sample. The small subset of TDEs that show only helium emission lines in their spectra have the longest rise times, the highest luminosities, and the lowest rates. A high detection rate of Bowen lines in TDEs with small photometric radii could be explained by the high density that is required for this fluorescence mechanism. The stellar debris can provide a source for this dense material. Diffusion of photons through this debris may explain why the rise and fade timescale of the TDEs in our sample are not correlated. We also report, for the first time, the detection of soft X-ray flares from a TDE on similar to day timescales. Based on the fact that the X-ray flares peak at a luminosity similar to the optical/UV blackbody luminosity, we attribute them to brief glimpses through a reprocessing layer that otherwise obscures the inner accretion flow.
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| 14. |
- Yao, Yuhan, et al.
(author)
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SN2019dge : A Helium-rich Ultra-stripped Envelope Supernova
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 900:1
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Journal article (peer-reviewed)abstract
- We present observations of ZTF18abfcmjw (SN2019dge), a helium-rich supernova with a fast-evolving light curve indicating an extremely low ejecta mass (approximate to 0.33M(circle dot)) and low kinetic energy (approximate to 1.3 x 10(50)erg). Early-time (<4 days after explosion) photometry reveals evidence of shock cooling from an extended helium-rich envelope of similar to 0.1 M-circle dot located similar to 1.2 x 10(13) cm from the progenitor. Early-time He II line emission and subsequent spectra show signatures of interaction with helium-rich circumstellar material, which extends from greater than or similar to 5 x 10(13)cm to greater than or similar to 2 x 10(16)cm. We interpret SN2019dge as a helium-rich supernova from an ultra-stripped progenitor, which originates from a close binary system consisting of a mass-losing helium star and a low-mass main-sequence star or a compact object (i.e., a white dwarf, a neutron star, or a black hole). We infer that the local volumetric birth rate of 19dge-like ultra-stripped SNe is in the range of 1400-8200 Gpc(-3)yr(-1) (i.e., 2%-12% of core-collapse supernova rate). This can be compared to the observed coalescence rate of compact neutron star binaries that are not formed by dynamical capture.
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