Showing papers by "Peter Nugent published in 2014"
Weizmann Institute of Science1, Kavli Institute for Theoretical Physics2, Las Cumbres Observatory Global Telescope Network3, University of Southampton4, University of Oxford5, University of Maryland, College Park6, Goddard Space Flight Center7, California Institute of Technology8, Chinese Academy of Sciences9, University of California, Santa Barbara10, University of Copenhagen11, Max Planck Society12, Lawrence Berkeley National Laboratory13, University of California, Berkeley14, Carnegie Institution for Science15, Princeton University16, University of Tokyo17, Boston University18
TL;DR: The results of a Palomar Transient Factory (PTF) archival search for blue transients that lie in the magnitude range between "normal" corecollapse and superluminous supernovae (i.e., with −21 ≤ M_(R (peak)) ≤ − 19) were presented in this article.
Abstract: We present the results of a Palomar Transient Factory (PTF) archival search for blue transients that lie in the magnitude range between "normal" core-collapse and superluminous supernovae (i.e., with –21 ≤ M_(R (peak)) ≤ – 19). Of the six events found after excluding all interacting Type IIn and Ia-CSM supernovae, three (PTF09ge, 09axc, and 09djl) are coincident with the centers of their hosts, one (10iam) is offset from the center, and a precise offset cannot be determined for two (10nuj and 11glr). All the central events have similar rise times to the He-rich tidal disruption candidate PS1-10jh, and the event with the best-sampled light curve also has similar colors and power-law decay. Spectroscopically, PTF09ge is He-rich, while PTF09axc and 09djl display broad hydrogen features around peak magnitude. All three central events are in low star formation hosts, two of which are E+A galaxies. Our spectrum of the host of PS1-10jh displays similar properties. PTF10iam, the one offset event, is different photometrically and spectroscopically from the central events, and its host displays a higher star formation rate. Finding no obvious evidence for ongoing galactic nuclei activity or recent star formation, we conclude that the three central transients likely arise from the tidal disruption of a star by a supermassive black hole. We compare the spectra of these events to tidal disruption candidates from the literature and find that all of these objects can be unified on a continuous scale of spectral properties. The accumulated evidence of this expanded sample strongly supports a tidal disruption origin for this class of nuclear transients.
439 citations
TL;DR: Wolf–Rayet-like wind signatures are identified, suggesting a progenitor of the WN(h) subclass (those WRSs with winds dominated by helium and nitrogen, with traces of hydrogen), consistent with recent theoretical predictions.
Abstract: The explosive fate of massive Wolf-Rayet stars (WRSs) is a key open question in stellar physics. An appealing option is that hydrogen-deficient WRSs are the progenitors of some hydrogen-poor supernova explosions of types IIb, Ib and Ic (ref. 2). A blue object, having luminosity and colours consistent with those of some WRSs, has recently been identified in pre-explosion images at the location of a supernova of type Ib (ref. 3), but has not yet been conclusively determined to have been the progenitor. Similar work has so far only resulted in non-detections. Comparison of early photometric observations of type Ic supernovae with theoretical models suggests that the progenitor stars had radii of less than 10(12) centimetres, as expected for some WRSs. The signature of WRSs, their emission line spectra, cannot be probed by such studies. Here we report the detection of strong emission lines in a spectrum of type IIb supernova 2013cu (iPTF13ast) obtained approximately 15.5 hours after explosion (by 'flash spectroscopy', which captures the effects of the supernova explosion shock breakout flash on material surrounding the progenitor star). We identify Wolf-Rayet-like wind signatures, suggesting a progenitor of the WN(h) subclass (those WRSs with winds dominated by helium and nitrogen, with traces of hydrogen). The extent of this dense wind may indicate increased mass loss from the progenitor shortly before its explosion, consistent with recent theoretical predictions.
313 citations
TL;DR: In this article, the authors describe the data reduction strategy and data products which are publicly available through the ESO archive as the Spectroscopic Survey Data Release 1 (SSDR1).
Abstract: The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and data products which are publicly available through the ESO archive as the Spectroscopic Survey Data Release 1 (SSDR1). PESSTO uses the New Technology Telescope with EFOSC2 and SOFI to provide optical and NIR spectroscopy and imaging. We target supernovae and optical transients brighter than 20.5mag for classification. Science targets are then selected for follow-up based on the PESSTO science goal of extending knowledge of the extremes of the supernova population. The EFOSC2 spectra cover 3345-9995A (at resolutions of 13-18 Angs) and SOFI spectra cover 0.935-2.53 micron (resolutions 23-33 Angs) along with JHK imaging. This data release contains spectra from the first year (April 2012 - 2013), consisting of all 814 EFOSC2 spectra and 95 SOFI spectra (covering 298 distinct objects), in standard ESO Phase 3 format. We estimate the accuracy of the absolute flux calibrations for EFOSC2 to be typically 15%, and the relative flux calibration accuracy to be about 5%. The PESSTO standard NIR reduction process does not yet produce high accuracy absolute spectrophotometry but the SOFI JHK imaging will improve this. Future data releases will focus on improving the automated flux calibration of the data products.
260 citations
Weizmann Institute of Science1, University of Southampton2, The Racah Institute of Physics3, California Institute of Technology4, Lawrence Berkeley National Laboratory5, University of California, Berkeley6, Carnegie Institution for Science7, Goddard Space Flight Center8, University of Texas at Austin9
TL;DR: In this article, a search for precursors in a sample of 16 Type IIn supernovae (SNe) is presented, and five SNe IIn that likely have at least one possible precursor event (PTF 10bjb, SN 2010mc, PTF 10weh, SN 2011ht, and PTF 12cxj), three of which are reported here for the first time.
Abstract: There is a growing number of Type IIn supernovae (SNe) which present an outburst prior to their presumably final explosion. These precursors may affect the SN display, and are likely related to poorly charted phenomena in the final stages of stellar evolution. By coadding Palomar Transient Factory (PTF) images taken prior to the explosion, here we present a search for precursors in a sample of 16 Type IIn SNe. We find five SNe IIn that likely have at least one possible precursor event (PTF 10bjb, SN 2010mc, PTF 10weh, SN 2011ht, and PTF 12cxj), three of which are reported here for the first time. For each SN we calculate the control time. We find that precursor events among SNe IIn are common: at the one-sided 99% confidence level, >50% of SNe IIn have at least one pre-explosion outburst that is brighter than 3 × 10^7 L_☉ taking place up to 1/3 yr prior to the SN explosion. The average rate of such precursor events during the year prior to the SN explosion is likely ≳ 1 yr^(–1), and fainter precursors are possibly even more common. Ignoring the two weakest precursors in our sample, the precursors rate we find is still on the order of one per year. We also find possible correlations between the integrated luminosity of the precursor and the SN total radiated energy, peak luminosity, and rise time. These correlations are expected if the precursors are mass-ejection events, and the early-time light curve of these SNe is powered by interaction of the SN shock and ejecta with optically thick circumstellar material.
222 citations
European Southern Observatory1, Yale University2, INAF3, University of Bonn4, University of Cambridge5, Weizmann Institute of Science6, Las Cumbres Observatory Global Telescope Network7, University of California, Santa Barbara8, University of Edinburgh9, Stockholm University10, Niels Bohr Institute11, University of Turku12, Queen's University Belfast13, University of California, Berkeley14, Space Telescope Science Institute15, University of Southampton16
TL;DR: In this article, optical spectra and light curves for three hydrogen-poor superluminous supernovae followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO) are presented.
Abstract: We present optical spectra and light curves for three hydrogen-poor superluminous supernovae followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). Time series spectroscopy from a fewdays aftermaximum light to 100 d later shows them to be fairly typical of this class, with spectra dominated by Ca II, MgII, FeII, and Si II, which evolve slowly over most of the post-peak photospheric phase. We determine bolometric light curves and apply simple fitting tools, based on the diffusion of energy input by magnetar spin-down, Ni-56 decay, and collision of the ejecta with an opaque circumstellar shell. We investigate how the heterogeneous light curves of our sample (combined with others from the literature) can help to constrain the possible mechanisms behind these events. We have followed these events to beyond 100-200 d after peak, to disentangle host galaxy light from fading supernova flux and to differentiate between the models, which predict diverse behaviour at this phase. Models powered by radioactivity require unrealistic parameters to reproduce the observed light curves, as found by previous studies. Both magnetar heating and circumstellar interaction still appear to be viable candidates. A large diversity is emerging in observed tail-phase luminosities, with magnetar models failing in some cases to predict the rapid drop in flux. This would suggest either that magnetars are not responsible, or that the X-ray flux from the magnetar wind is not fully trapped. The light curve of one object shows a distinct rebrightening at around 100 d after maximum light. We argue that this could result either from multiple shells of circumstellar material, or from a magnetar ionization front breaking out of the ejecta.
192 citations
TL;DR: In this article, the authors present a sample of 16 supernovae (SNe IIn) for which they have Palomar Transient Factory (PTF) observations obtained prior to the SN explosion.
Abstract: There is a growing number of supernovae (SNe), mainly of Type IIn, which present an outburst prior to their presumably final explosion. These precursors may affect the SN display, and are likely related to some poorly charted phenomena in the final stages of stellar evolution. Here we present a sample of 16 SNe IIn for which we have Palomar Transient Factory (PTF) observations obtained prior to the SN explosion. By coadding these images taken prior to the explosion in time bins, we search for precursor events. We find five Type IIn SNe that likely have at least one possible precursor event, three of which are reported here for the first time. For each SN we calculate the control time. Based on this analysis we find that precursor events among SNe IIn are common: at the one-sided 99% confidence level, more than 50% of SNe IIn have at least one pre-explosion outburst that is brighter than absolute magnitude -14, taking place up to 1/3 yr prior to the SN explosion. The average rate of such precursor events during the year prior to the SN explosion is likely larger than one per year, and fainter precursors are possibly even more common. We also find possible correlations between the integrated luminosity of the precursor, and the SN total radiated energy, peak luminosity, and rise time. These correlations are expected if the precursors are mass-ejection events, and the early-time light curve of these SNe is powered by interaction of the SN shock and ejecta with optically thick circumstellar material.
179 citations
Max Planck Society1, University of Southampton2, INAF3, University of Würzburg4, California Institute of Technology5, Lawrence Berkeley National Laboratory6, University of California, Berkeley7, University of California, Santa Barbara8, Las Cumbres Observatory Global Telescope Network9, Weizmann Institute of Science10, University of Oxford11, Swinburne University of Technology12, University of Tokyo13, Yale University14
TL;DR: In this article, the authors used a Monte Carlo radiative transfer code to constrain the density structure and the abundance stratification in the SN ejecta, and derived Fe abundance in the outermost layer is consistent with the metallicity at the SN explosion site in M101.
Abstract: Hubble Space Telescope spectroscopic observations of the nearby Type Ia supernova (SN Ia) SN 2011fe, taken on 10 epochs from −13.1 to +40.8 d relative to B-band maximum light, and spanning the far-ultraviolet (UV) to the near-infrared (IR) are presented. This spectroscopic coverage makes SN 2011fe the best-studied local SN Ia to date. SN 2011fe is a typical moderately luminous SN Ia with no evidence for dust extinction. Its near-UV spectral properties are representative of a larger sample of local events (Maguire et al.). The near-UV to optical spectra of SN 2011fe are modelled with a Monte Carlo radiative transfer code using the technique of ‘abundance tomography’, constraining the density structure and the abundance stratification in the SN ejecta. SN 2011fe was a relatively weak explosion, with moderate Fe-group yields. The density structures of the classical model W7 and of a delayed detonation model were tested. Both have shortcomings. An ad hoc density distribution was developed which yields improved fits and is characterized by a high-velocity tail, which is absent in W7. However, this tail contains less mass than delayed detonation models. This improved model has a lower energy than one-dimensional explosion models matching typical SNe Ia (e.g. W7, WDD1; Iwamoto et al.). The derived Fe abundance in the outermost layer is consistent with the metallicity at the SN explosion site in M101 (∼0.5 Z_⊙). The spectroscopic rise-time (∼19 d) is significantly longer than that measured from the early optical light curve, implying a ‘dark phase’ of ∼1 d. A longer rise-time has significant implications when deducing the properties of the white dwarf and binary system from the early photometric behaviour.
172 citations
Stockholm University1, California Institute of Technology2, Carnegie Institution for Science3, University of California, Berkeley4, Lawrence Berkeley National Laboratory5, Weizmann Institute of Science6, Institut d'Astrophysique de Paris7, Las Cumbres Observatory Global Telescope Network8, University of California, Santa Barbara9, Kavli Institute for Theoretical Physics10, Physical Research Laboratory11, University of Maryland, College Park12, Goddard Space Flight Center13, University of Geneva14, Texas Tech University15, Centra16, Harvard University17, University of Hawaii18
TL;DR: The discovery of SN 2014J in the nearby galaxy M82 is reported in this article, where the authors use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise.
Abstract: We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, near-IR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, RV ≲ 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location. © 2014. The American Astronomical Society. All rights reserved.
164 citations
Weizmann Institute of Science1, Space Sciences Laboratory2, North Carolina State University3, Los Alamos National Laboratory4, California Institute of Technology5, University of California, Berkeley6, Goddard Space Flight Center7, Technical University of Denmark8, Tel Aviv University9, Lawrence Berkeley National Laboratory10, University of Southampton11
TL;DR: In this article, the mass of the circumstellar material within 10 cm of the progenitor of SN 2010jl was estimated and shown to be at least 9 × 10^50 erg.
Abstract: Some supernovae (SNe) may be powered by the interaction of the SN ejecta with a large amount of circumstellar matter (CSM). However, quantitative estimates of the CSM mass around such SNe are missing when the CSM material is optically thick. Specifically, current estimators are sensitive to uncertainties regarding the CSM density profile and the ejecta velocity. Here we outline a method to measure the mass of the optically thick CSM around such SNe. We present new visible-light and X-ray observations of SN 2010jl (PTF 10aaxf), including the first detection of an SN in the hard X-ray band using NuSTAR. The total radiated luminosity of SN 2010jl is extreme—at least 9 × 10^50 erg. By modeling the visible-light data, we robustly show that the mass of the circumstellar material within ~10^16 cm of the progenitor of SN 2010jl was in excess of 10 M_☉. This mass was likely ejected tens of years prior to the SN explosion. Our modeling suggests that the shock velocity during shock breakout was ~6000 km s^–1, decelerating to ~2600 km s^–1 about 2 yr after maximum light. Furthermore, our late-time NuSTAR and XMM spectra of the SN presumably provide the first direct measurement of SN shock velocity 2 yr after the SN maximum light—measured to be in the range of 2000-4500 km s^–1 if the ions and electrons are in equilibrium, and ≳ 2000 km s^–1 if they are not in equilibrium. This measurement is in agreement with the shock velocity predicted by our modeling of the visible-light data. Our observations also show that the average radial density distribution of the CSM roughly follows an r^–2 law. A possible explanation for the ≳ 10 M_☉ of CSM and the wind-like profile is that they are the result of multiple pulsational pair instability events prior to the SN explosion, separated from each other by years.
142 citations
Weizmann Institute of Science1, Max Planck Society2, San Diego State University3, Institute for the Physics and Mathematics of the Universe4, University of Southampton5, University of Maryland, College Park6, University of California, Berkeley7, Goddard Space Flight Center8, California Institute of Technology9, Stockholm University10, Niels Bohr Institute11, Kavli Institute for Theoretical Physics12, Las Cumbres Observatory Global Telescope Network13, Carnegie Institution for Science14, Lawrence Berkeley National Laboratory15
TL;DR: In this article, a hydrogen-poor superluminous supernova (SLSN) was discovered by the intermediate Palomar Transient Factory, iPTF 13ajg at a redshift of z = 07403, derived from narrow absorption lines.
Abstract: We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg At a redshift of z = 07403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M_(u,AB) = –225, one of the most luminous supernovae to date The observed bolometric peak luminosity of iPTF 13ajg is 32 × 10^(44) erg s^(–1), while the estimated total radiated energy is 13 × 10^(51) erg We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope From Voigt profile fitting, we derive the column densities log N(Mg I) =1194 ± 006, log N(Mg II) =147 ± 03, and log N(Fe II) =1425 ± 010 These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars This suggests that the environments of hydrogen-poor SLSNe and GRBs are different From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s^(–1), indicating a low-mass host galaxy No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR_([OII]) < 007 M_☉ yr^(-1) Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g_(AB) ≈ 270 and R_(AB) ≥ 260 mag, corresponding to M_(B,Vega) ≳ –177 mag
142 citations
Australian National University1, Lawrence Berkeley National Laboratory2, Pierre-and-Marie-Curie University3, University of Washington4, Yale University5, University of Bonn6, Claude Bernard University Lyon 17, University of Lyon8, University of California, Berkeley9, Max Planck Society10, New York University11
TL;DR: In this paper, a sample of normal type Ia supernovae from the Nearby Supernova Factory dataset with spectrophotometry at sufficiently late phases was used to estimate the ejected mass using the bolometric light curve.
Abstract: We present a sample of normal type Ia supernovae from the Nearby Supernova Factory dataset with spectrophotometry at sufficiently late phases to estim ate the ejected mass using the bolometric light curve. We measure 56 Ni masses from the peak bolometric luminosity, then compare the luminosity in the 56 Co-decay tail to the expected rate of radioactive energy release from ejecta of a given mass. We infer the ejected mass in a Bayesian context using a semi-analytic model of the ejecta, incorporating constra ints from contemporary numerical models as priors on the density structure and distribution o f 56 Ni throughout the ejecta. We find a strong correlation between ejected mass and light curv e decline rate, and consequently 56 Ni mass, with ejected masses in our data ranging from 0.9‐1.4 M⊙. Most fast-declining (SALT2x1 < 1) normal SNe Ia have significantly sub-Chandrasekhar ejecte d masses in our fiducial analysis.
TL;DR: The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope as mentioned in this paper.
Abstract: The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the full wavelength range of 0.2-2 μm. A total-to-selective extinction, R_V ≥ 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields R_V = 1.4 ± 0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, A _λ/AV = (λ/λ_V )^p as expected from multiple scattering of light, with p = –2.1 ± 0.1. After correcting for differences in reddening, SN 2014J appears to be very similar to SN 2011fe over the 14 broadband filter light curves used in our study.
University of Oxford1, University of Southampton2, INAF3, University of California, Berkeley4, Lawrence Berkeley National Laboratory5, University of California, Santa Barbara6, Las Cumbres Observatory Global Telescope Network7, Weizmann Institute of Science8, University of Maryland, College Park9, Goddard Space Flight Center10, California Institute of Technology11, Australian Astronomical Observatory12, Yale University13, University of Copenhagen14
TL;DR: In this article, spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF) were presented.
Abstract: We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.
TL;DR: In this article, a hydrogen-poor superluminous supernova (SLSN) was discovered by the intermediate Palomar Transient Factory: iPTF13ajg. At a redshift of z=0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude M(u,AB)=-22.5, one of the most luminous supernovae to date.
Abstract: We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory: iPTF13ajg. At a redshift of z=0.7403, derived from narrow absorption lines, iPTF13ajg peaked at an absolute magnitude M(u,AB)=-22.5, one of the most luminous supernovae to date. The uBgRiz light curves, obtained with the P48, P60, NOT, DCT, and Keck telescopes, and the nine-epoch spectral sequence secured with the Keck and the VLT (covering 3 rest-frame months), are tied together photometrically to provide an estimate of the flux evolution as a function of time and wavelength. The observed bolometric peak luminosity of iPTF13ajg is 3.2x10^44 erg/s, while the estimated total radiated energy is 1.3x10^51 erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the VLT. From Voigt-profile fitting, we derive the column densities log N(Mg I)=11.94+-0.06, log N(Mg II)=14.7+-0.3, and log N(Fe II)=14.25+-0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs), whose progenitors are also thought to be massive stars. This suggests that the environments of SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a strict lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. No host-galaxy emission lines are detected, leading to an upper limit on the unobscured star-formation rate of SFR([OII]) =26.0 mag, which roughly corresponds to M(B,Vega) >~ -17.7 mag. [abridged]
European Southern Observatory1, University of Southampton2, University of Oxford3, Weizmann Institute of Science4, INAF5, Las Cumbres Observatory Global Telescope Network6, University of California, Santa Barbara7, University of California, Berkeley8, Lawrence Berkeley National Laboratory9, Max Planck Society10, University of Lyon11, Carnegie Institution for Science12, Tel Aviv University13, University of Texas at Austin14, Yale University15, University of Copenhagen16
TL;DR: In this paper, the optical spectra of 264 low-redshift (SNe Ia) phases were investigated and it was found that C II features are more likely to be found in SNE Ia having narrower light curves.
Abstract: We present an investigation of the optical spectra of 264 low-redshift (z 40 per cent of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that C II features are more likely to be found in SNe Ia having narrower light curves.
George Washington University1, California Institute of Technology2, Weizmann Institute of Science3, National Radio Astronomy Observatory4, Pennsylvania State University5, Carnegie Institution for Science6, University of Oxford7, University of California, Berkeley8, Goddard Space Flight Center9, Max Planck Society10, University of Copenhagen11, Liverpool John Moores University12, Lawrence Berkeley National Laboratory13
TL;DR: In this paper, the authors presented the discovery, classification, and extensive panchromatic (from radio to X-ray) follow-up observations of PTF11qcj, a supernova (SN) discovered by the Palomar Transient Factory (PTF).
Abstract: We present the discovery, classification, and extensive panchromatic (from radio to X-ray) follow-up observations of PTF11qcj, a supernova (SN) discovered by the Palomar Transient Factory (PTF). Our observations with the Karl G. Jansky Very Large Array show that this event is radio-loud: PTF11qcj reached a radio peak luminosity comparable to that of the famous gamma-ray-burst-associated SN 1998bw (L_(5 GHz) ≈ 10^(29) erg s^(−1) Hz^(−1)). PTF11qcj is also detected in X-rays with the Chandra Observatory, and in the infrared band with Spitzer. Our multi-wavelength analysis probes the SN interaction with circumstellar material. The radio observations suggest a progenitor mass-loss rate of ~10^(−4) M_☉ yr^(−1) × (v_w/1000 km s^(−1)), and a velocity of ≈0.3–0.5 c for the fastest moving ejecta (at ≈10 days after explosion). However, these estimates are derived assuming the simplest model of SN ejecta interacting with a smooth circumstellar wind, and do not account for possible inhomogeneities in the medium and asphericity of the explosion. The radio data show deviations from such a simple model, as well as a late-time re-brightening. The X-ray flux from PTF11qcj is compatible with the high-frequency extrapolation of the radio synchrotron emission (within the large uncertainties). A light echo from pre-existing dust is in agreement with our infrared data. Our pre-explosion data from the PTF suggest that a precursor eruption of absolute magnitude M_r ≈ −13 mag may have occurred ≈2.5 yr prior to the SN explosion. Overall, PTF11qcj fits the expectations from the explosion of a Wolf–Rayet star. Precursor eruptions may be a feature characterizing the final pre-explosion evolution of such stars.
Max Planck Society1, University of California, Berkeley2, Lawrence Berkeley National Laboratory3, University of California, Santa Cruz4, University of Barcelona5, Institute for the Physics and Mathematics of the Universe6, Carnegie Mellon University7, Kapteyn Astronomical Institute8, Valparaiso University9, Aix-Marseille University10, INAF11, Space Telescope Science Institute12, Ehime University13
TL;DR: In this paper, the first observations of foreground Lyα forest absorption from high-redshift galaxies are presented, targeting 24 star-forming galaxies (SFGs) with z 2.3-2.8 within a 5' × 14' region of the COSMOS field.
Abstract: We present the first observations of foreground Lyα forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with z ~ 2.3-2.8 within a 5' × 14' region of the COSMOS field. The transverse sightline separation is ~2 h -1 Mpc comoving, allowing us to create a tomographic reconstruction of the three-dimensional (3D) Lyα forest absorption field over the redshift range 2.20 2. Our map reveals significant structures with >~ 10 h -1 Mpc extent, including several spanning the entire transverse breadth, providing qualitative evidence for the filamentary structures predicted to exist in the high-redshift cosmic web. Simulated reconstructions with the same sightline sampling, spectral resolution, and signal-to-noise ratio recover the salient structures present in the underlying 3D absorption fields. Using data from other surveys, we identified 18 galaxies with known redshifts coeval with our map volume, enabling a direct comparison with our tomographic map. This shows that galaxies preferentially occupy high-density regions, in qualitative agreement with the same comparison applied to simulations. Our results establish the feasibility of the CLAMATO survey, which aims to obtain Lyα forest spectra for ~1000 SFGs over ~1 deg2 of the COSMOS field, in order to map out the intergalactic medium large-scale structure at langzrang ~ 2.3 over a large volume (100 h -1 Mpc)3.
TL;DR: In this paper, the authors compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.
Abstract: During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.
Weizmann Institute of Science1, University of Southampton2, California Institute of Technology3, Lawrence Berkeley National Laboratory4, University of California, Berkeley5, Liverpool John Moores University6, Goddard Space Flight Center7, Stockholm University8, Carnegie Institution for Science9, University of Tokyo10
TL;DR: In this article, the authors present a sample of 15 supernova ejecta IIn for which they have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory.
Abstract: Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ~104 km s–1). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.
TL;DR: In this article, a tomographic reconstruction of the 3D Ly$\alpha$ forest absorption field over the redshift range of 2.3-2.8 was presented.
Abstract: We present the first observations of foreground Lyman-$\alpha$ forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with $z\sim 2.3-2.8$ within a $5' \times 15'$ region of the COSMOS field. The transverse sightline separation is $\sim 2\,h^{-1}\mathrm{Mpc}$ comoving, allowing us to create a tomographic reconstruction of the 3D Ly$\alpha$ forest absorption field over the redshift range $2.20\leq z\leq 2.45$. The resulting map covers $6\,h^{-1}\mathrm{Mpc} \times 14\,h^{-1}\mathrm{Mpc}$ in the transverse plane and $230\,h^{-1}\mathrm{Mpc}$ along the line-of-sight with a spatial resolution of $\approx 3.5\,h^{-1}\mathrm{Mpc}$, and is the first high-fidelity map of large-scale structure on $\sim\mathrm{Mpc}$ scales at $z>2$. Our map reveals significant structures with $\gtrsim 10\,h^{-1}\mathrm{Mpc}$ extent, including several spanning the entire transverse breadth, providing qualitative evidence for the filamentary structures predicted to exist in the high-redshift cosmic web. Simulated reconstructions with the same sightline sampling, spectral resolution, and signal-to-noise ratio recover the salient structures present in the underlying 3D absorption fields. Using data from other surveys, we identified 18 galaxies with known redshifts coeval with our map volume enabling a direct comparison to our tomographic map. This shows that galaxies preferentially occupy high-density regions, in qualitative agreement with the same comparison applied to simulations. Our results establishes the feasibility of the CLAMATO survey, which aims to obtain Ly$\alpha$ forest spectra for $\sim 1000$ SFGs over $\sim 1 \,\mathrm{deg}^2$ of the COSMOS field, in order to map out IGM large-scale structure at $\langle z \rangle \sim 2.3$ over a large volume $(100\,h^{-1}\mathrm{Mpc})^3$.
California Institute of Technology1, Kavli Institute for Theoretical Physics2, University of California, Santa Barbara3, National Tsing Hua University4, University of Maryland, College Park5, Goddard Space Flight Center6, Weizmann Institute of Science7, Carnegie Institution for Science8, Lawrence Berkeley National Laboratory9, University of California, Berkeley10
TL;DR: The most recent outburst of the recurrent nova (RN) system RX J0045.4+4154 in the Andromeda galaxy has enabled the unprecedented study of a massive (M > 1.3 M) accreting white dwarf (WD).
Abstract: The intermediate Palomar Transient Factory (iPTF) detection of the most recent outburst of the recurrent nova (RN) system RX J0045.4+4154 in the Andromeda galaxy has enabled the unprecedented study of a massive (M > 1.3 M) accreting white dwarf (WD). We detected this nova as part of the near-daily iPTF monitoring of M31 to a depth of R 21 mag and triggered optical photometry, spectroscopy and soft X-ray monitoring of the outburst. Peaking at an absolute magnitude of MR= -6.6 mag, and with a decay time of 1 mag per day, it is a faint and very fast nova. It shows optical emission lines of He/N and expansion velocities of 1900-2600 km s-1 1-4 days after the optical peak. The Swift monitoring of the X-ray evolution revealed a supersoft source (SSS) with kT eff 90-110 eV that appeared within 5 days after the optical peak, and lasted only 12 days. Most remarkably, this is not the first event from this system, rather it is an RN with a time between outbursts of approximately 1 yr, the shortest known. Recurrent X-ray emission from this binary was detected by ROSAT in 1992 and 1993, and the source was well characterized as a M > 1.3 M WD SSS. Based on the observed recurrence time between different outbursts, the duration and effective temperature of the SS phase, MESA models of accreting WDs allow us to constrain the accretion rate to and WD mass >1.30 M. If the WD keeps 30% of the accreted material, it will take less than a Myr to reach core densities high enough for carbon ignition (if made of C/O) or electron capture (if made of O/Ne) to end the binary evolution. © 2014. The American Astronomical Society. All rights reserved..
Fermilab1, University of Pennsylvania2, University of Portsmouth3, ETH Zurich4, University College London5, University of Illinois at Urbana–Champaign6, Stanford University7, University of Michigan8, Texas A&M University9, Ludwig Maximilian University of Munich10, Ohio State University11, Max Planck Society12, Austin Peay State University13, Lawrence Berkeley National Laboratory14, Argonne National Laboratory15, University of Manchester16, University of Nottingham17, Brookhaven National Laboratory18
TL;DR: The Dark Energy Survey (DES) as mentioned in this paper is a next generation optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae.
Abstract: The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES started its first observing season on August 31, 2013 and observed for 105 nights through mid-February 2014. This paper describes DES “Year 1” (Y1), the strategy and goals for the first year's data, provides an outline of the operations procedures, lists the efficiency of survey operations and the causes of lost observing time, provides details about the quality of the first year's data, and hints at the “Year 2” plan and outlook.
Weizmann Institute of Science1, Max Planck Society2, Hebrew University of Jerusalem3, New York University4, University of Oxford5, University of California, Santa Barbara6, Tel Aviv University7, University of California, Berkeley8, Lawrence Berkeley National Laboratory9, California Institute of Technology10, Carnegie Institution for Science11, University of Tokyo12, University of Copenhagen13
TL;DR: In this article, a Type Ic supernova lacking spectroscopic signatures of H and He was observed to have a slowly declining light curve (LC) that cannot be powered by 56Ni/56Co radioactivity, the common energy source for Type Ic SNe.
Abstract: We present our observations of SN 2010mb, a Type Ic supernova (SN) lacking spectroscopic signatures of H and He. SN 2010mb has a slowly declining light curve (LC) (~600 days) that cannot be powered by 56Ni/56Co radioactivity, the common energy source for Type Ic SNe. We detect signatures of interaction with hydrogen-free circumstellar material including a blue quasi-continuum and, uniquely, narrow oxygen emission lines that require high densities (~109 cm–3). From the observed spectra and LC, we estimate that the amount of material involved in the interaction was ~3 M ☉. Our observations are in agreement with models of pulsational pair-instability SNe described in the literature.
Weizmann Institute of Science1, University of California, Berkeley2, Lawrence Berkeley National Laboratory3, University of Lyon4, California Institute of Technology5, Carnegie Institution for Science6, Goddard Space Flight Center7, University of Maryland, College Park8, University of Southampton9, Tsinghua University10
TL;DR: In this article, optical photometric and spectroscopic observations of the Type Ibn (SN 2006jc-like) supernova (SN) iPTF13beo have been presented.
Abstract: We present optical photometric and spectroscopic observations of the Type Ibn (SN 2006jc-like) supernova (SN) iPTF13beo. Detected by the intermediate Palomar Transient Factory ∼3 h after the estimated first light, iPTF13beo is the youngest and the most distant (∼430 Mpc) Type Ibn event ever observed. The iPTF13beo light curve is consistent with light curves of other Type Ibn SNe and with light curves of fast Type Ic events, but with a slightly faster rise-time of two days. In addition, the iPTF13beo R-band light curve exhibits a double-peak structure separated by ∼9 d, not observed before in any Type Ibn SN. A low-resolution spectrum taken during the iPTF13beo rising stage is featureless, while a late-time spectrum obtained during the declining stage exhibits narrow and intermediate-width He i and Si ii features with full width at half-maximum ≈2000–5000 km s^(−1) and is remarkably similar to the prototypical SN Ibn 2006jc spectrum. We suggest that our observations support a model of a massive star exploding in a dense He-rich circumstellar medium (CSM). A shock breakout in a CSM model requires an eruption releasing a total mass of ∼0.1 M_⊙ over a time-scale of couple of weeks prior to the SN explosion.
Australian National University1, University of California, Berkeley2, Texas A&M University3, Aarhus University4, Carnegie Institution for Science5, Las Cumbres Observatory Global Telescope Network6, Dartmouth College7, California State University8, Australian Astronomical Observatory9, Louisiana State University10, University of Cambridge11, Weizmann Institute of Science12, European Southern Observatory13, Stockholm University14, University of Southampton15, Max Planck Society16, Yale University17, University of Bonn18, Lawrence Berkeley National Laboratory19
TL;DR: Scalozo et al. as mentioned in this paper used ultraviolet photometry from Swift, ground-based optical photometry, and corrections from a near-infrared photometric template to construct the bolometric (1600-23 800 A) light curve out to 45 d past B-band maximum light.
Abstract: Author(s): Scalzo, RA; Childress, M; Tucker, B; Yuan, F; Schmidt, B; Brown, PJ; Contreras, C; Morrell, N; Hsiao, E; Burns, C; Phillips, MM; Campillay, A; Gonzalez, C; Krisciunas, K; Stritzinger, M; Graham, ML; Parrent, J; Valenti, S; Lidman, C; Schaefer, B; Scott, N; Fraser, M; Gal-Yam, A; Inserra, C; Maguire, K; Smartt, SJ; Sollerman, J; Sullivan, M; Taddia, F; Yaron, O; Young, DR; Taubenberger, S; Baltay, C; Ellman, N; Feindt, U; Hadjiyska, E; McKinnon, R; Nugent, PE; Rabinowitz, D; Walke, ES | Abstract: We present photospheric-phase observations of LSQ12gdj, a slowly declining, UV-bright Type Ia supernova. Classified well before maximum light, LSQ12gdj has extinction-corrected absolute magnitude MB = -19.8, and pre-maximum spectroscopic evolution similar to SN 1991T and the super-Chandrasekhar-mass SN 2007if. We use ultraviolet photometry from Swift, ground-based optical photometry, and corrections from a near-infrared photometric template to construct the bolometric (1600-23 800 A) light curve out to 45 d past B-band maximum light. We estimate that LSQ12gdj produced 0.96 ± 0.07 M· of 56Ni, with an ejected mass near or slightly above the Chandrasekhar mass. As much as 27 per cent of the flux at the earliest observed phases, and 17 per cent at maximum light, is emitted bluewards of 3300 A. The absence of excess luminosity at late times, the cutoff of the spectral energy distribution bluewards of 3000 A and the absence of narrow line emission and strong Na I D absorption all argue against a significant contribution from ongoing shock interaction. However, ~10 per cent of LSQ12gdj's luminosity near maximum light could be produced by the release of trapped radiation, including kinetic energy thermalized during a brief interaction with a compact, hydrogen-poor envelope (radius l1013 cm) shortly after explosion; such an envelope arises generically in double-degenerate merger scenarios.
Scuola Normale Superiore di Pisa1, Yale University2, Max Planck Society3, INAF4, Space Sciences Laboratory5, Weizmann Institute of Science6, University of California, Berkeley7, Goddard Space Flight Center8, California Institute of Technology9, Princeton University10, Tel Aviv University11, University of Texas at Austin12, University of Southampton13, Lawrence Berkeley National Laboratory14, University of Arizona15, Johns Hopkins University Applied Physics Laboratory16, Russian Academy of Sciences17, Hiroshima University18, Saitama University19, Aoyama Gakuin University20
TL;DR: In this paper, optical photometry and spectroscopy of the broadlined Type Ic supernova (SN Ic-BL) PTF10qts, which was discovered as part of the Palomar Transient Factory, was presented.
Abstract: We present optical photometry and spectroscopy of the broad-lined Type Ic supernova (SN Ic-BL) PTF10qts, which was discovered as part of the Palomar Transient Factory. The SN was located in a dwarf galaxy of magnitude r = 21.1 at a redshift z = 0.0907. We find that the R-band light curve is a poor proxy for bolometric data and use photometric and spectroscopic data to construct and constrain the bolometric light curve. The derived bolometric magnitude at maximum light is M_bol = −18.51 ± 0.2 mag, comparable to that of SN 1998bw (M_bol = −18.7 mag) which was associated with a gamma-ray burst (GRB). PTF10qts is one of the most luminous SNe Ic-BL observed without an accompanying GRB. We estimate the physical parameters of the explosion using data from our programme of follow-up observations, finding that it produced a larger mass of radioactive nickel compared to other SNe Ic-BL with similar inferred ejecta masses and kinetic energies. The progenitor of the event was likely an ∼20 M_⊙ star.
Weizmann Institute of Science1, California Institute of Technology2, CFA Institute3, University of Haifa4, Technion – Israel Institute of Technology5, Tel Aviv University6, ETH Zurich7, University of Maryland, College Park8, Las Cumbres Observatory Global Telescope Network9, UCB10, University of Southampton11
TL;DR: In this article, the authors present the first results from a simultaneous GALEX/PTF search for early UV emission from core collapse supernovae (SNe) and compare their detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GalEX observations, combined with volumetric SN rates.
Abstract: The radius and surface composition of an exploding massive star,as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 solar, explosion energies of 10^51 erg, and ejecta masses of 10 solar masses. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase ( 100 SNe per year (~0.5 SN per deg^2), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.
TL;DR: Kim et al. as discussed by the authors examined the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spec-photometric time series, with global host-galaxy properties.
Abstract: Kim et al. (2013) [K13] introduced a new methodology for determining peak- brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spec- trophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ? 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at ? 1?, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement the Hubble residual step with host mass is 0.045 ? 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch param- eters: Steps at > 2? significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light- curve width and color around peak (similar to the ∆m15 and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20 to 30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.
24 Mar 2014
TL;DR: This paper evaluates a novel implementation of the classifier in GLADE, a parallel data processing system that combines the efficiency of a database with the extensibility of Map-Reduce, and shows how each stage in the classifiers maps optimally into GLADE tasks by taking advantage of the unique features of the system.
Abstract: Palomar Transient Factory is a comprehensive detection system for the identification and classification of transient astrophysical objects. The central piece in the identification pipeline is represented by an automated classifier that distinguishes between real and bogus objects with high accuracy. Given that the classifier has to identify the most significant transients out of a large number of candidates in near real-time, the response time it provides is of critical importance. In this paper, we present an experimental study that evaluates a novel implementation of the classifier in GLADEa parallel data processing system that combines the efficiency of a database with the extensibility of Map-Reduce. We show how each stage in the classifier candidate identification, pruning, and contextual realbogus maps optimally into GLADE tasks by taking advantage of the unique features of the systemrange-based data partitioning, columnar storage, multi-query execution, and in-database support for complex aggregate computation. The result is an efficient classifier implementation capable to process a new set of acquired images in a matter of minutes even on a low-end server. For comparison, an optimized PostgreSQL implementation of the classifier takes hours on the same machine.
Princeton University1, Carnegie Institution for Science2, University of California, Berkeley3, Lawrence Berkeley National Laboratory4, Weizmann Institute of Science5, University of California, Santa Barbara6, Las Cumbres Observatory Global Telescope Network7, University of Southampton8, Stockholm University9, California Institute of Technology10, University of Maryland, College Park11, Goddard Space Flight Center12, INAF13, University of Oxford14, Max Planck Society15, San Diego State University16, University of Tokyo17
TL;DR: In this paper, the authors present the results of a systematic study of 1077 hydrogen-poor supernovae discovered by the Palomar Transient Factory, leading to nine new members of this peculiar class.
Abstract: Since the discovery of the unusual prototype SN 2002cx, the eponymous class of low-velocity, hydrogen-poor supernovae has grown to include at most another two dozen members identified from several heterogeneous surveys, in some cases ambiguously. Here we present the results of a systematic study of 1077 hydrogen-poor supernovae discovered by the Palomar Transient Factory, leading to nine new members of this peculiar class. Moreover we find there are two distinct subclasses based on their spectroscopic, photometric, and host galaxy properties: The "SN 2002cx-like" supernovae tend to be in later-type or more irregular hosts, have more varied and generally dimmer luminosities, have longer rise times, and lack a Ti II trough when compared to the "SN 2002es-like" supernovae. None of our objects show helium, and we counter a previous claim of two such events. We also find that these transients comprise 5.6+17-3.7% (90% confidence) of all SNe Ia, lower compared to earlier estimates. Combining our objects with the literature sample, we propose that these subclasses have two distinct physical origins.