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Sökning: WFRF:(Hamuy M.)

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1.
  • Valenti, S., et al. (författare)
  • PESSTO spectroscopic classification of La Silla-Quest Transients
  • 2012
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • PESSTO is the "Public ESO Spectroscopic Survey of Transient Objects" (http://www.pessto.org) using the ESO New Technology Telescope (NTT) at La Silla and the EFOSC2 (optical) and SOFI (near-IR) spectrographs. It is one of two currently running public spectroscopic surveys at ESO. The survey details are as follows: - PESSTO has 90 nights per year on the NTT: 9 lunations (August to April), 10 nights per lunation (we are not observing May-July).
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2.
  • Barbarino, C., et al. (författare)
  • SN 2012ec : mass of the progenitor from PESSTO follow-up of the photospheric phase
  • 2015
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 448:3, s. 2312-2331
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 x 10(42) erg s(-1) and duration similar to 90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(Ni-56) = 0.040 +/- 0.015 M-circle dot from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 M-circle dot, an initial progenitor radius of 1.6 x 10(13) cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in pre-explosion images, for which an initial mass of M = 14-22 M-circle dot was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators.
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3.
  • Pastorello, A., et al. (författare)
  • INTERACTING SUPERNOVAE AND SUPERNOVA IMPOSTORS : SN 2009ip, IS THIS THE END?
  • 2013
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 767:1, s. 1-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the results of a three-year-long dedicated monitoring campaign of a restless luminous blue variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically in the optical and near-infrared domains. We monitored a number of erupting episodes in the past few years, and increased the density of our observations during eruptive episodes. In this paper, we present the full historical data set from 2009 to 2012 with multi-wavelength dense coverage of the two high-luminosity events between 2012 August and September. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We label them the 2012a event (lasting similar to 50 days) with a peak of 3x10(41) erg s(-1), and the 2012b event (14 day rise time, still ongoing) with a peak of 8 x 1042 erg s(-1). The latter event reached an absolute R-band magnitude of about -18, comparable to that of a core-collapse supernova (SN). Our historical monitoring has detected high-velocity spectral features (similar to 13,000 km s(-1)) in 2011 September, one year before the current SN-like event. This implies that the detection of such high-velocity outflows cannot, conclusively, point to a core-collapse SN origin. We suggest that the initial peak in the 2012a event was unlikely to be due to a faint core-collapse SN. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.
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4.
  • Hsiao, E. Y., et al. (författare)
  • Carnegie Supernova Project-II : The Near-infrared Spectroscopy Program
  • 2019
  • Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
  • Tidskriftsartikel (refereegranskat)abstract
    • Shifting the focus of Type Ia supernova (SN Ia) cosmology to the near infrared (NIR) is a promising way to significantly reduce the systematic errors, as the strategy minimizes our reliance on the empirical width-luminosity relation and uncertain dust laws. Observations in the NIR are also crucial for our understanding of the origins and evolution of these events, further improving their cosmological utility. Any future experiments in the rest-frame NIR will require knowledge of the SN Ia NIR spectroscopic diversity, which is currently based on a small sample of observed spectra. Along with the accompanying paper, Phillips et al., we introduce the Carnegie Supernova Project-II (CSP-II), to follow-up nearby SNe Ia in both the optical and the NIR. In particular, this paper focuses on the CSP-II NIR spectroscopy program, describing the survey strategy, instrumental setups, data reduction, sample characteristics, and future analyses on the data set. In collaboration with the Harvard-Smithsonian Center for Astrophysics (CfA) Supernova Group, we obtained 661 NIR spectra of 157 SNe Ia. Within this sample, 451 NIR spectra of 90 SNe Ia have corresponding CSP-II follow-up light curves. Such a sample will allow detailed studies of the NIR spectroscopic properties of SNe Ia, providing a different perspective on the properties of the unburned material; the radioactive and stable nickel produced; progenitor magnetic fields; and searches for possible signatures of companion stars.
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5.
  • Levesque, E. M., et al. (författare)
  • THE HIGH-METALLICITY EXPLOSION ENVIRONMENT OF THE RELATIVISTIC SUPERNOVA 2009bb
  • 2010
  • Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 709:1, s. l26-L31
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the environment of the nearby (d approximate to 40 Mpc) broad-lined Type Ic supernova (SN) 2009bb. This event was observed to produce a relativistic outflow likely powered by a central accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of interstellar medium properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site properties to observations of LGRB and broad-lined SN Ic host environments on optical emission line ratio diagnostic diagrams. Based on these analyses, we find that the SN 2009bb explosion site has a metallicity between 1.7 Z(circle dot) and 3.5 Z(circle dot), in agreement with other broad-lined SN Ic host environments and at odds with the low-redshift LGRB host environments and recently proposed maximum metallicity limits for relativistic explosions. We consider the implications of these findings and the impact that SN 2009bb's unusual explosive properties and environment have on our understanding of the key physical ingredient that enables some SNe to produce a relativistic outflow.
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6.
  • Soderberg, A. M., et al. (författare)
  • A relativistic type Ibc supernova without a detected gamma-ray burst
  • 2010
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 463:7280, s. 513-515
  • Tidskriftsartikel (refereegranskat)abstract
    • Long duration gamma-ray bursts (GRBs) mark(1) the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered(2) by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested(3) in the pulse of gamma-rays and a long-lived radio afterglow. Until now, central-engine driven supernovae have been discovered exclusively through their gamma-ray emission, yet it is expected(4) that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches(5,6) for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred(7) rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported(8).
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7.
  • Soderberg, A. M., et al. (författare)
  • Discovery of a Relativistic Supernova Without a Gamma-ray Trigger
  • 2009
  • Annan publikation (populärvet., debatt m.m.)abstract
    • Type Ibc supernovae (SNe Ibc) mark the gravitational collapse of some massive stars (M > 20 Msun) propelling several solar masses of material to typical velocities of ~10,000 km/s. The closely-related but exceedingly rare class of long-duration gamma-ray bursts (GRBs) produce, in addition, a relativistic outflow powered by a central engine (accreting black hole or neutron star) and have been found exclusively through their gamma-ray signal. Here we report the discovery of luminous radio emission from the seemingly ordinary Type Ibc SN 2009bb which outshines that of all other SNe Ibc observed on a comparable timescale. These observations require a substantial mildly-relativistic outflow and indicate that the explosion was powered by a central engine, thus representing the first such event discovered without the aid of a gamma-ray trigger. A comparison with our extensive radio survey of SNe Ibc reveals that the fraction of such events is low (roughly 1 percent), measured independently from, and yet consistent with, the inferred rate of nearby GRBs. This discovery marks the observational realization that long-wavelength surveys will soon rival gamma-ray satellites in pinpointing nearby engine-driven explosions.
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8.
  • Takats, K., et al. (författare)
  • SN 2009N : linking normal and subluminous Type II-P SNe
  • 2014
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 438:1, s. 368-387
  • Tidskriftsartikel (refereegranskat)abstract
    • We present ultraviolet, optical, near-infrared photometry and spectroscopy of SN 2009N in NGC 4487. This object is a Type II-P supernova with spectra resembling those of subluminous II-P supernovae, while its bolometric luminosity is similar to that of the intermediate-luminosity SN 2008in. We created SYNOW models of the plateau phase spectra for line identification and to measure the expansion velocity. In the near-infrared spectra we find signs indicating possible weak interaction between the supernova ejecta and the pre-existing circumstellar material. These signs are also present in the previously unpublished near-infrared spectra of SN 2008in. The distance to SN 2009N is determined via the expanding photosphere method and the standard candle method as D = 21.6 +/- 1.1 Mpc. The produced nickel-mass is estimated to be similar to 0.020 +/- 0.004 M-circle dot. We infer the physical properties of the progenitor at the explosion through hydrodynamical modelling of the observables. We find the values ofthe total energy as similar to 0.48 x 10(51) erg, the ejected mass as similar to 11.5 M-circle dot, and the initial radius as similar to 287 R-circle dot.
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9.
  • Leloudas, G., et al. (författare)
  • The normal Type Ia SN 2003hv out to very late phases
  • 2009
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 505:1, s. 265-279
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: We study a thermonuclear supernova (SN), emphasizing very late phases. Methods: An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. This includes 82 epochs of optical imaging, 24 epochs of near-infrared (NIR) imaging, and 10 epochs of optical spectroscopy. These data are combined with published nebular-phase IR spectra, and the observations are compared to model light curves and synthetic nebular spectra. Results: SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B-band decline-rate parameter, Δ m15(B) = 1.61 ± 0.02. The blueshift of the most isolated [Fe ii] lines in the nebular-phase optical spectrum appears consistent with those observed in the IR at similar epochs. At late times there is a prevalent color evolution from the optical toward the NIR bands. We present the latest-ever detection of a SN Ia in the NIR in Hubble Space Telescope images. The study of the ultraviolet/optical/infrared (UVOIR) light curve reveals that a substantial fraction of the flux is “missing” at late times. Between 300 and 700 days past maximum brightness, the UVOIR light curve declines linearly following the decay of radioactive 56Co, assuming full and instantaneous positron trapping. At 700 days we detect a possible slowdown of the decline in optical-bands, mainly in the V-band. Conclusions: The data are incompatible with a dramatic infrared catastrophe (IRC). However, the idea that an IRC occurred in the densest regions before 350 days can explain the missing flux from the UVOIR wavelengths and the flat-topped profiles in the NIR. We argue that such a scenario is possible if the ejecta are clumpy. The observations suggest that positrons are most likely trapped in the ejecta. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Programmes 073.D-0294(AB), 074.D-0259(BC) and 075.D-0116(AB)), Cerro Tololo Inter-American Observatory, Lick Observatory, Las Campanas Observatory, Siding Spring Observatory, and the Hubble Space Telescope. Tables 3, 4, and Appendix A are only available in electronic form at http://www.aanda.org
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10.
  • Spiro, S., et al. (författare)
  • Low luminosity Type II supernovae - II. Pointing towards moderate mass precursors
  • 2014
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 439:3, s. 2873-2892
  • Tidskriftsartikel (refereegranskat)abstract
    • We present new data for five underluminous Type II-plateau supernovae (SNe IIP), namely SN 1999gn, SN 2002gd, SN 2003Z, SN 2004eg and SN 2006ov. This new sample of low-luminosity SNe IIP (LL SNe IIP) is analysed together with similar objects studied in the past. All of them show a flat light-curve plateau lasting about 100 d, an underluminous late-time exponential tail, intrinsic colours that are unusually red, and spectra showing prominent and narrow P Cygni lines. A velocity of the ejected material below 10(3) km s(-1) is inferred from measurements at the end of the plateau. The Ni-56 masses ejected in the explosion are very small (< 10(-2) M-circle dot). We investigate the correlations among Ni-56 mass, expansion velocity of the ejecta and absolute magnitude in the middle of the plateau, confirming the main findings of Hamuy, according to which events showing brighter plateau and larger expansion velocities are expected to produce more Ni-56. We propose that these faint objects represent the LL tail of a continuous distribution in parameters space of SNe IIP. The physical properties of the progenitors at the explosion are estimated through the hydrodynamical modelling of the observables for two representative events of this class, namely SN 2005cs and SN 2008in. We find that the majority of LL SNe IIP, and quite possibly all, originate in the core collapse of intermediate-mass stars, in the mass range 10-15 M-circle dot.
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11.
  • Valenti, S., et al. (författare)
  • SN 2009jf : a slow-evolving stripped-envelope core-collapse supernova
  • 2011
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 416:4, s. 3138-3159
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an extensive set of photometric and spectroscopic data for SN 2009jf, a nearby Type Ib supernova (SN), spanning from similar to 20 d before B-band maximum to 1 yr after maximum. We show that SN 2009jf is a slowly evolving and energetic stripped-envelope SN and is likely from a massive progenitor (25-30 M(circle dot)). The large progenitor's mass allows us to explain the complete hydrogen plus helium stripping without invoking the presence of a binary companion. The SN occurred close to a young cluster, in a crowded environment with ongoing star formation. The spectroscopic similarity with the He-poor Type Ic SN 2007gr suggests a common progenitor for some SNe Ib and Ic. The nebular spectra of SN 2009jf are consistent with an asymmetric explosion, with an off-centre dense core. We also find evidence that Herich Ib SNe have a rise time longer than other stripped-envelope SNe, however confirmation of this result and further observations are needed.
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12.
  • Stritzinger, M. D., et al. (författare)
  • The Carnegie Supernova Project I : Photometry data release of low-redshift stripped-envelope supernovae
  • 2018
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 609
  • Tidskriftsartikel (refereegranskat)abstract
    • The first phase of the Carnegie Supernova Project (CSP-I) was a dedicated supernova follow-up program based at the Las Campanas Observatory that collected science data of young, low-redshift supernovae between 2004 and 2009. Presented in this paper is the CSP-I photometric data release of low-redshift stripped-envelope core-collapse supernovae. The data consist of optical (uBgVri) photometry of 34 objects, with a subset of 26 having near-infrared (YJH) photometry. Twenty objects have optical pre-maximum coverage with a subset of 12 beginning at least five days prior to the epoch of B-band maximum brightness. In the near-infrared, 17 objects have pre-maximum observations with a subset of 14 beginning at least five days prior to the epoch of J-band maximum brightness. Analysis of this photometric data release is presented in companion papers focusing on techniques to estimate host-galaxy extinction and the light-curve and progenitor star properties of the sample. The analysis of an accompanying visual-wavelength spectroscopy sample of similar to 150 spectra will be the subject of a future paper.
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13.
  • Taddia, Francesco, et al. (författare)
  • Supernova 2008J : early time observations of a heavily reddened SN 2002ic-like transient
  • 2012
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 545, s. L7-
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: We provide additional observational evidence that some Type Ia supernovae (SNe Ia) show signatures of circumstellar interaction (CSI) with hydrogen-rich material. Methods: Early phase optical and near-infrared (NIR) light curves and spectroscopy of SN 2008J obtained by the Carnegie Supernova Project are studied and compared to those of SNe 2002ic and 2005gj. Our NIR spectrum is the first obtained for a 2002ic-like object extending up to 2.2 μm. A published high-resolution spectrum is used to provide insight on the circumstellar material (CSM). Results: SN 2008J is found to be affected by AV ~ 1.9 mag of extinction and to closely resemble SN 2002ic. Spectral and color comparison to SNe 2002ic and 2005gj suggests RV < 3.1. Spectral decomposition reveals the underlying SN emission matches a 1991T-like event and, since SN 2008J is as luminous as SN 2005gj (Vmax = -20.3 mag), we conclude that their CSI emissions are similarly robust. The high-resolution spectrum reveals narrow emission lines produced from un-shocked gas characterized by a wind velocity of ~50 km s-1. We conclude that SN 2008J best matches an explosion of a SN Ia that interacts with its CSM. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 080.A-0516).Figure 4 and Tables 1-6 are available in electronic form at http://www.aanda.org
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14.
  • Wang, Xiaofeng, et al. (författare)
  • Evidence for type ia supernova diversity from ultraviolet observations with the hubble space telescope
  • 2012
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 749:2, s. 126-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.
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15.
  • Chakraborti, Sayan, et al. (författare)
  • A MISSING-LINK IN THE SUPERNOVA-GRB CONNECTION : THE CASE OF SN 2012ap
  • 2015
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 805:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion for a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.
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16.
  • Oates, S. R., et al. (författare)
  • Multiwavelength observations of the Type IIb supernova 2009mg
  • 2012
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 424:2, s. 1297-1306
  • Tidskriftsartikel (refereegranskat)abstract
    • We present Swift Ultra-Violet Optical Telescope and X-Ray Telescope (XRT) observations, and visual wavelength spectroscopy of the Type IIb supernova (SN) 2009mg, discovered in the Sb galaxy ESO 121-G26. The observational properties of SN 2009mg are compared to the prototype Type IIb SNe 1993J and 2008ax, with which we find many similarities. However, minor differences are discernible including SN 2009mg not exhibiting an initial fast decline or u-band upturn as observed in the comparison objects, and its rise to maximum is somewhat slower leading to slightly broader light curves. The late-time temporal index of SN 2009mg, determined from 40 d post-explosion, is consistent with the decay rate of SN 1993J, but inconsistent with the decay of 56Co. This suggests leakage of ?-rays out of the ejecta and a stellar mass on the small side of the mass distribution. Our XRT non-detection provides an upper limit on the mass-loss rate of the progenitor of . Modelling of the SN light curve indicates a kinetic energy of , an ejecta mass of and a 56Ni mass of 0.10 +/- 0.01 M?.
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17.
  • Pignata, Giuliano, et al. (författare)
  • SN 2009bb : A PECULIAR BROAD-LINED TYPE Ic SUPERNOVA
  • 2011
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 728:1, s. 14-
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultraviolet, optical, and near-infrared photometry and optical spectroscopy of the broad-lined Type Ic supernova (SN) 2009bb are presented, following the flux evolution from -10 to +285 days past B-band maximum. Thanks to the very early discovery, it is possible to place tight constraints on the SN explosion epoch. The expansion velocities measured from near maximum spectra are found to be only slightly smaller than those measured from spectra of the prototype broad-lined SN 1998bw associated with GRB 980425. Fitting an analytical model to the pseudobolometric light curve of SN 2009bb suggests that 4.1 +/- 1.9M(circle dot) of material was ejected with 0.22 +/- 0.06 M(circle dot) of it being (56)Ni. The resulting kinetic energy is 1.8 +/- 0.7 x 10(52) erg. This, together with an absolute peak magnitude of M(B) = -18.36 +/- 0.44, places SN 2009bb on the energetic and luminous end of the broad-lined Type Ic (SN Ic) sequence. Detection of helium in the early time optical spectra accompanied with strong radio emission and high metallicity of its environment makes SN 2009bb a peculiar object. Similar to the case for gamma-ray bursts (GRBs), we find that the bulk explosion parameters of SN 2009bb cannot account for the copious energy coupled to relativistic ejecta, and conclude that another energy reservoir (a central engine) is required to power the radio emission. Nevertheless, the analysis of the SN 2009bb nebular spectrum suggests that the failed GRB detection is not imputable to a large angle between the line-of-sight and the GRB beamed radiation. Therefore, if a GRB was produced during the SN 2009bb explosion, it was below the threshold of the current generation of gamma-ray instruments.
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18.
  • Stritzinger, M. D., et al. (författare)
  • Optical and near-IR observations of the faint and fast 2008ha-like supernova 2010ae
  • 2014
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 561, s. A146-
  • Tidskriftsartikel (refereegranskat)abstract
    • A comprehensive set of optical and near-infrared (NIR) photometry and spectroscopy is presented for the faint and fast 2008ha-like supernova (SN) 2010ae. Contingent on the adopted value of host extinction, SN 2010ae reached a peak brightness of -13.8 > M-V > -15.3 mag, while modeling of the UVOIR light curve suggests it produced 0.003-0.007 M-circle dot of Ni-56, ejected 0.30-0.60 M-circle dot of material, and had an explosion energy of 0.04-0.30 x 10(51) erg. The values of these explosion parameters are similar to the peculiar SN 2008ha -for which we also present previously unpublished early phase optical and NIR light curves - and places these two transients at the faint end of the 2002cx-like SN population. Detailed inspection of the post-maximum NIR spectroscopic sequence indicates the presence of a multitude of spectral features, which are identified through SYNAPPS modeling to be mainly attributed to Co II. Comparison with a collection of published and unpublished NIR spectra of other 2002cx-like SNe, reveals that a Co II footprint is ubiquitous to this subclass of transients, providing a link to Type Ia SNe. A visual-wavelength spectrum of SN 2010ae obtained at +252 days past maximum shows a striking resemblance to a similar epoch spectrum of SN 2002cx. However, subtle differences in the strength and ratio of calcium emission features, as well as diversity among similar epoch spectra of other 2002cx-like SNe indicates a range of physical conditions of the ejecta, highlighting the heterogeneous nature of this peculiar class of transients.
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19.
  • Taddia, Francesco, et al. (författare)
  • Carnegie Supernova Project : Observations of Type IIn supernovae
  • 2013
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 555, s. A10-
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims. The observational diversity displayed by various Type IIn supernovae (SNe IIn) is explored and quantified. In doing so, a more coherent picture ascribing the variety of observed SNe IIn types to particular progenitor scenarios is sought. Methods. Carnegie Supernova Project (CSP) optical and near-infrared light curves and visual-wavelength spectroscopy of the Type IIn SNe 2005kj, 2006aa, 2006bo, 2006qq, and 2008fq are presented. Combined with previously published observations of the Type IIn SNe 2005ip and 2006jd, the full CSP sample is used to derive physical parameters that describe the nature of the interaction between the expanding SN ejecta and the circumstellar material (CSM). Results. For each SN of our sample, we find counterparts, identifying objects similar to SNe 1994W (SN 2006bo), 1998S (SN 2008fq), and 1988Z (SN 2006qq). We present the unprecedented initial u-band plateau of SN 2006aa, and its peculiar late-time luminosity and temperature evolution. For each SN, mass-loss rates of 10(-4)-10(-2) M-circle dot yr(-1) are derived, assuming the CSM was formed by steady winds. Typically wind velocities of a few hundred km s(-1) are also computed. Conclusions. The CSP SN IIn sample seems to be divided into subcategories rather than to have exhibited a continuum of observational properties. The wind and mass-loss parameters would favor a luminous blue variable progenitor scenario. However, the assumptions made to derive those parameters strongly influence the results, and therefore, other progenitor channels behind SNe IIn cannot be excluded at this time.
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20.
  • Takats, K., et al. (författare)
  • SN 2009ib : a Type II-P supernova with an unusually long plateau
  • 2015
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 450:3, s. 3137-3154
  • Tidskriftsartikel (refereegranskat)abstract
    • We present optical and near-infrared photometry and spectroscopy of SN 2009ib, a Type II-P supernova in NGC 1559. This object has moderate brightness, similar to those of the intermediate-luminosity SNe 2008in and 2009N. Its plateau phase is unusually long, lasting for about 130 d after explosion. The spectra are similar to those of the subluminous SN 2002gd, with moderate expansion velocities. We estimate the Ni-56 mass produced as 0.046 +/- A 0.015 M-aS (TM). We determine the distance to SN 2009ib using both the expanding photosphere method (EPM) and the standard candle method. We also apply EPM to SN 1986L, a Type II-P SN that exploded in the same galaxy. Combining the results of different methods, we conclude the distance to NGC 1559 as D = 19.8 +/- A 3.0 Mpc. We examine archival, pre-explosion images of the field taken with the Hubble Space Telescope, and find a faint source at the position of the SN, which has a yellow colour [(V - I)(0) = 0.85 mag]. Assuming it is a single star, we estimate its initial mass as M-ZAMS = 20 M-aS (TM). We also examine the possibility, that instead of the yellow source the progenitor of SN 2009ib is a red supergiant star too faint to be detected. In this case, we estimate the upper limit for the initial zero-age main sequence (ZAMS) mass of the progenitor to be similar to 14-17 M-aS (TM). In addition, we infer the physical properties of the progenitor at the explosion via hydrodynamical modelling of the observables, and estimate the total energy as similar to 0.55 x 10(51) erg, the pre-explosion radius as similar to 400 R-aS (TM), and the ejected envelope mass as similar to 15 M-aS (TM), which implies that the mass of the progenitor before explosion was similar to 16.5-17 M-aS (TM).
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21.
  • Maeda, K., et al. (författare)
  • An asymmetric explosion as the origin of spectral evolution diversity in type Ia supernovae
  • 2010
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 466:7302, s. 82-85
  • Tidskriftsartikel (refereegranskat)abstract
    • Type Ia supernovae form an observationally uniform class of stellar explosions, in that more luminous objects have smaller decline-rates. This one-parameter behaviour allows type Ia supernovae to be calibrated as cosmological `standard candles', and led to the discovery of an accelerating Universe. Recent investigations, however, have revealed that the true nature of type Ia supernovae is more complicated. Theoretically, it has been suggested that the initial thermonuclear sparks are ignited at an offset from the centre of the white-dwarf progenitor, possibly as a result of convection before the explosion. Observationally, the diversity seen in the spectral evolution of type Ia supernovae beyond the luminosity-decline-rate relation is an unresolved issue. Here we report that the spectral diversity is a consequence of random directions from which an asymmetric explosion is viewed. Our findings suggest that the spectral evolution diversity is no longer a concern when using type Ia supernovae as cosmological standard candles. Furthermore, this indicates that ignition at an offset from the centre is a generic feature of type Ia supernovae.
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22.
  • Stritzinger, Maximilian, et al. (författare)
  • Multi-wavelength Observations of the Enduring Type IIn Supernovae 2005ip and 2006jd
  • 2012
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 756:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broadband UV, optical, and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Our observations of SN 2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are compared to reported X-ray measurements to understand the nature of the progenitor. Both objects display a number of similarities with the 1988Z-like subclass of SN IIn including (1) remarkably similar early- and late-phase optical spectra, (2) a variety of high-ionization coronal lines, (3) long-duration optical and near-IR emission, and (4) evidence of cold and warm dust components. However, diversity is apparent, including an unprecedented late-time r-band excess in SN 2006jd. The observed differences are attributed to differences between the mass-loss history of the progenitor stars. We conclude that the progenitor of SN 2006jd likely experienced a significant mass-loss event during its pre-SN evolution akin to the great 19th century eruption of η Carinae. Contrarily, as advocated by Smith et al., the circumstellar environment of SN 2005ip is found to be more consistent with a clumpy wind progenitor.
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23.
  • Taddia, Francesco, et al. (författare)
  • The Type II supernovae 2006V and 2006au : two SN 1987A-like events
  • 2012
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. Supernova 1987A revealed that a blue supergiant (BSG) star can end its life as a core-collapse supernova (SN). SN 1987A and other similar objects exhibit properties that distinguish them from ordinary Type II Plateau (IIP) SNe, whose progenitors are believed to be red supergiants (RSGs). Similarities among 1987A-like events include a long rise to maximum, early luminosity fainter than that of normal Type IIP SNe, and radioactivity acting as the primary source powering the light curves.Aims. We present and analyze two SNe monitored by the Carnegie Supernova Project that are reminiscent of SN 1987A.Methods. Optical and near-infrared (NIR) light curves, and optical spectroscopy of SNe 2006V and 2006au are presented. These observations are compared to those of SN 1987A, and are used to estimate properties of their progenitors.Results. Both objects exhibit a slow rise to maximum and light curve evolution similar to that of SN 1987A. At the earliest epochs, SN 2006au also displays an initial dip which we interpret as the signature of the adiabatic cooling phase that ensues shock break-out. SNe 2006V and 2006au are both found to be bluer, hotter and brighter than SN 1987A. Spectra of SNe 2006V and 2006au are similar to those of SN 1987A and other normal Type II objects, although both consistently exhibit expansion velocities higher than SN 1987A. Semi-analytic models are fit to the UVOIR light curve of each object from which physical properties of the progenitors are estimated. This yields ejecta mass estimates of Mej ≈ 20 M⊙, explosion energies of E ≈ 2−3 × 1051 erg s-1, and progenitor radii of R ≈ 75−100 R⊙ for both SNe.Conclusions. The progenitors of SNe 2006V and 2006au were most likely BSGs with a larger explosion energy as compared to that of SN 1987A.
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24.
  • de Jaeger, T., et al. (författare)
  • SN 2011A : A LOW-LUMINOSITY INTERACTING TRANSIENT WITH A DOUBLE PLATEAU AND STRONG SODIUM ABSORPTION
  • 2015
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 807:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present optical photometry and spectroscopy of the optical transient SN 2011A. Our data span 140 days after discovery including BVRI u'g'r'i'z' photometry and 11 epochs of optical spectroscopy. Originally classified as a type IIn supernova (SN IIn) due to the presence of narrow Ha emission, this object shows exceptional characteristics. First, the light curve shows a double plateau, a property only observed before in the impostor SN 1997bs. Second, SN 2011A has a very low luminosity (M-V = -15.72), placing it between normal luminous SNe IIn and SN impostors. Third, SN 2011A shows low velocity and high equivalent width absorption close to the sodium doublet, which increases with time and is most likely of circumstellar origin. This evolution is also accompanied by a change in line profile; when the absorption becomes stronger, a P Cygni profile appears. We discuss SN 2011A in the context of interacting SNe IIn and SN impostors, which appears to confirm the uniqueness of this transient. While we favor an impostor origin for SN 2011A, we highlight the difficulty in differentiating between terminal and non-terminal interacting transients.
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25.
  • Folatelli, Gaston, et al. (författare)
  • UNBURNED MATERIAL IN THE EJECTA OF TYPE Ia SUPERNOVAE
  • 2012
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 745:1, s. 74-
  • Tidskriftsartikel (refereegranskat)abstract
    • The presence of unburned material in the ejecta of normal Type Ia supernovae (SNe Ia) is investigated using early-time spectroscopy obtained by the Carnegie Supernova Project. The tell-tale signature of pristine material from a C+O white dwarf progenitor star is the presence of carbon, as oxygen is also a product of carbon burning. The most prominent carbon lines in optical spectra of SNe Ia are expected to arise from C II. We find that at least 30% of the objects in the sample show an absorption at approximate to 6300 angstrom which is attributed to C II lambda 6580. An alternative identification of this absorption as Ha is considered to be unlikely. These findings imply a larger incidence of carbon in SNe Ia ejecta than previously noted. We show how observational biases and physical conditions may hide the presence of weak C II lines, and account for the scarcity of previous carbon detections in the literature. This relatively large frequency of carbon detections has crucial implications on our understanding of the explosive process. Furthermore, the identification of the 6300 angstrom absorptions as carbon would imply that unburned material is present at very low expansion velocities, merely approximate to 1000 km s(-1) above the bulk of Si II. Based on spectral modeling, it is found that the detections are consistent with a mass of carbon of 10(-3) to 10(-2) M-circle dot. The presence of this material so deep in the ejecta would imply substantial mixing, which may be related to asymmetries of the flame propagation. Another possible explanation for the carbon absorptions may be the existence of clumps of unburned material along the line of sight. However, the uniformity of the relation between C II and Si II velocities is not consistent with such small-scale asymmetries. The spectroscopic and photometric properties of SNe Ia with and without carbon signatures are compared. A trend toward bluer color and lower luminosity at maximum light is found for objects which show carbon.
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