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Sample records for ia sn 2005bl

  1. Comparison of recent SnIa datasets

    SciTech Connect

    Sanchez, J.C. Bueno; Perivolaropoulos, L.; Nesseris, S. E-mail: nesseris@nbi.ku.dk

    2009-11-01

    We rank the six latest Type Ia supernova (SnIa) datasets (Constitution (C), Union (U), ESSENCE (Davis) (E), Gold06 (G), SNLS 1yr (S) and SDSS-II (D)) in the context of the Chevalier-Polarski-Linder (CPL) parametrization w(a) = w{sub 0}+w{sub 1}(1−a), according to their Figure of Merit (FoM), their consistency with the cosmological constant (ΛCDM), their consistency with standard rulers (Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO)) and their mutual consistency. We find a significant improvement of the FoM (defined as the inverse area of the 95.4% parameter contour) with the number of SnIa of these datasets ((C) highest FoM, (U), (G), (D), (E), (S) lowest FoM). Standard rulers (CMB+BAO) have a better FoM by about a factor of 3, compared to the highest FoM SnIa dataset (C). We also find that the ranking sequence based on consistency with ΛCDM is identical with the corresponding ranking based on consistency with standard rulers ((S) most consistent, (D), (C), (E), (U), (G) least consistent). The ranking sequence of the datasets however changes when we consider the consistency with an expansion history corresponding to evolving dark energy (w{sub 0},w{sub 1}) = (−1.4,2) crossing the phantom divide line w = −1 (it is practically reversed to (G), (U), (E), (S), (D), (C)). The SALT2 and MLCS2k2 fitters are also compared and some peculiar features of the SDSS-II dataset when standardized with the MLCS2k2 fitter are pointed out. Finally, we construct a statistic to estimate the internal consistency of a collection of SnIa datasets. We find that even though there is good consistency among most samples taken from the above datasets, this consistency decreases significantly when the Gold06 (G) dataset is included in the sample.

  2. Tests of Environmental Effects on SN Ia Production

    NASA Astrophysics Data System (ADS)

    Strolger, Louis-Gregory; Wolff, Schuyler; Pease, April

    2010-02-01

    The largely unknown type Ia supernova (SN Ia) mechanism remains one of the largest sources of possible systematic uncertainty in achieving precise measures of dark energy. The host galaxy environments of SNe Ia provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant Ia event, and possibly the success in ultimately yielding a SN Ia event. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search (NGSS) project. The purpose of this study is to uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star- formation, or metallicity. Here, we propose to begin our analysis using any of NOAO-access 4m + spectrograph to obtain broad SEDs, R_23 metallicities, and star formation rates for 14 of the ~30 host galaxies (all z⪉0.1) from the NGSS sample. These data will be combined with the remaining sample to be sought in the 2010B and future semesters. The sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the SNfactory, SDSS, and other surveys, and ultimately steer future investigations towards more precise SN Ia cosmology.

  3. Tests of Environmental Effects on SN Ia Production

    NASA Astrophysics Data System (ADS)

    Strolger, Louis-Gregory; van Dyk, Schuyler; Wolff, Schuyler; Campbell, Lachlan; Sadler, Suzanna; Pease, April

    2011-02-01

    The largely unknown type Ia supernova mechanism remains one of the largest sources of possible systematic uncertainty in achieving precise measures of dark energy. The host galaxy environments of SNe Ia provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant Ia event, and possibly the success in ultimately yielding a SN Ia event. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search project. This study will uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star-formation, or metallicity. Here, we propose to continue our analysis using the Mayall 4m + RCSP to obtain broad SEDs, R_23 metallicities, and star formation rates for 18 of the 25 remaining host galaxies (all z≤0.15) from the NGSS sample (20 targets were obtained in the 2010 semesters). These data will be combined with the remaining sample to be completed in the 2011B semester. The sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the LOSS, SDSS, SNfactory and other surveys, and ultimately steer future investigations towards more precise SN Ia cosmology.

  4. SN 1991bg - A type Ia supernova with a difference

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Phillips, Mark M.; Wells, Lisa A.; Suntzeff, N. B.; Hamuy, Mario; Schommer, R. A.; Walker, A. R.; Gonzalez, L.; Ugarte, P.

    1993-01-01

    While SN 1991bg is an unusual type Ia SN in such a feature as the brief duration of the photospheric phase, which ended only two weeks after maximum, it shares with other Ia SNs strong Si II and Ca II lines near maximum light. In addition, the light and color curve slopes are almost identical with the templates at late times. The spectral evolution of SN 1991bg is also unique but not unrecognizable; nevertheless, the peculiarities associated with this event complicate the fundamental question as to whether the Ia SNs make good standard candles.

  5. Premaximum observations of the type Ia SN 1990N

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Filippenko, Alexei V.; Shields, Joseph C.; Foltz, Craig B.; Phillips, Mark M.; Sonneborn, George

    1991-01-01

    Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most of the observed differences are due to the early epoch of the observations. The most significant characteristics are (1) the high velocities of Ca and Si up to 22,000 km/s; (2) the presence of Co and Fe 2 weeks before maximum; and (3) the more rapid increase in the UV flux compared to the optical. The most popular models for white dwarf deflagration that have provided the standard interpretation for SN Ia's at maximum light do not reproduce the high velocities of Ca II and Si II lines observed in SN 1990N.

  6. Spectrum synthesis of the Type Ia supernovae SN 1992A and SN 1981B

    NASA Technical Reports Server (NTRS)

    Nugent, Peter; Baron, E.; Hauschildt, Peter H.; Branch, David

    1995-01-01

    We present non-local thermodynamic equilibrium (non-LTE) synthetic spectra for the Type Ia supernovae SN 1992A and SN 1981B, near maximum light. At this epoch both supernovae were observed from the UV through the optical. This wide spectral coverage is essential for determining the density structure of a SN Ia. Our fits are in good agreement with observation and provide some insight as to the differences between these supernovae. We also discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on the decay of Ni-56 and Cepheid variable stars.

  7. The circumstellar environment of pre-SN Ia systems

    NASA Astrophysics Data System (ADS)

    Harvey, E.; Redman, M. P.; Boumis, P.; Kopsacheili, M.; Akras, S., Sabin, L.; Jurkic, T.

    2016-06-01

    Here we explore the possible preexisting circumstellar debris of supernova type Ia systems. Classical, symbiotic and recurrent novae all accrete onto roughly solar mass white dwarfs from main sequence or Mira type companions and result in thermonuclear runaways and expulsion of the accreted material at high velocity. The expelled material forms a fast moving shell that eventually slows to planetary nebula expansion velocities within several hundred years. All such systems are recurrent and thousands of shells (each of about 0.001 Mo) snow plough into the environment. As these systems involve common envelope binaries the material is distributed in a non-spherical shell. These systems could be progenitors of some SN Ia and thus explode into environments with large amounts of accumulated gas and dust distributed in thin non-spherical shells. Such shells should be observable around 100 years after a SN Ia event in a radio flash as the SN Ia debris meets that of the ejected material of the systems previous incarnation.

  8. SNLS: Constraints on SN Ia progenitors from host galaxies

    NASA Astrophysics Data System (ADS)

    Howell, D. A.; Sullivan, M.; Le Borgne, D.; Hodsman, A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I. M.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, T. J.; Filliol, M.; Perlmutter, S.; Tao, C.; SNLS Collaboration

    2005-12-01

    We investigate the single degenerate and double degenerate progenitor scenarios for SNe Ia using Pegase galaxy population synthesis models fit to the SN Ia host galaxy ugriz data from the SNLS. For the single degenerate scenario, we present the results of a Monte Carlo sumulation combining limits on the star formation history of the model hosts and analytic contraints on the allowable primary and secondary mass distributions. Under the assuption that all SNe are from the single degenerate channel, we find that SNe in star forming galaxies have a wide range of secondary masses, with a median of about 5 solar masses. Supernovae from the older galaxy population must come from a narrower distribution of secondary masses, with a median less than two solar masses. When combined with the differing stretch distributions for the two populations, this argues that there is a light curve shape-secondary mass correlation if the single degenerate model is the only route to an SN Ia. However, the single degenerate scenario has difficulty producing the observed SN Ia rate in old populations so the double degenerate scenario may be preferred.

  9. A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN 2007if?

    NASA Astrophysics Data System (ADS)

    Zhang, Ju-Jia; Wang, Xiao-Feng; Sasdelli, Michele; Zhang, Tian-Meng; Liu, Zheng-Wei; Mazzali, Paolo A.; Meng, Xiang-Cun; Maeda, Keiichi; Chen, Jun-Cheng; Huang, Fang; Zhao, Xu-Lin; Zhang, Kai-Cheng; Zhai, Qian; Pian, Elena; Wang, Bo; Chang, Liang; Yi, Wei-Min; Wang, Chuan-Jun; Wang, Xue-Li; Xin, Yu-Xin; Wang, Jian-Guo; Lun, Bao-Li; Zheng, Xiang-Ming; Zhang, Xi-Liang; Fan, Yu-Feng; Bai, Jin-Ming

    2016-02-01

    Photometric and spectroscopic observations of a slowly declining, luminous Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are presented. SN 2011hr is found to peak at {M}B\\=\\-19.84+/- 0.40 {mag}, with a postmaximum decline rate Δm15(B) = 0.92 ± 0.03 mag. From the maximum-light bolometric luminosity, L\\=\\(2.30+/- 0.90)× {10}43 {erg} {{{s}}}-1, we estimate the mass of synthesized 56Ni in SN 2011hr to be M{(}56{Ni})\\=\\1.11+/- 0.43 {M}⊙ . SN 2011hr appears more luminous than SN 1991T at around maximum light, and the absorption features from its intermediate-mass elements (IMEs) are noticeably weaker than those of the latter at similar phases. Spectral modeling suggests that SN 2011hr has IMEs of ˜0.07 {M}⊙ in the outer ejecta, which is much lower than the typical value of normal SNe Ia (i.e., 0.3-0.4 {M}⊙ ) and is also lower than the value of SN 1991T (i.e., ˜0.18 {M}⊙ ). These results indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf progenitor that experienced a more efficient burning process in the explosion. Nevertheless, it is still possible that SN 2011hr may serve as a transitional object connecting the SN 1991T-like SNe Ia with a superluminous subclass like SN 2007if given that the latter also shows very weak IMEs at all phases.

  10. A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN 2007if?

    NASA Astrophysics Data System (ADS)

    Zhang, Ju-Jia; Wang, Xiao-Feng; Sasdelli, Michele; Zhang, Tian-Meng; Liu, Zheng-Wei; Mazzali, Paolo A.; Meng, Xiang-Cun; Maeda, Keiichi; Chen, Jun-Cheng; Huang, Fang; Zhao, Xu-Lin; Zhang, Kai-Cheng; Zhai, Qian; Pian, Elena; Wang, Bo; Chang, Liang; Yi, Wei-Min; Wang, Chuan-Jun; Wang, Xue-Li; Xin, Yu-Xin; Wang, Jian-Guo; Lun, Bao-Li; Zheng, Xiang-Ming; Zhang, Xi-Liang; Fan, Yu-Feng; Bai, Jin-Ming

    2016-02-01

    Photometric and spectroscopic observations of a slowly declining, luminous Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are presented. SN 2011hr is found to peak at {M}B\\=\\-19.84+/- 0.40 {mag}, with a postmaximum decline rate Δm15(B) = 0.92 ± 0.03 mag. From the maximum-light bolometric luminosity, L\\=\\(2.30+/- 0.90)× {10}43 {erg} {{{s}}}-1, we estimate the mass of synthesized 56Ni in SN 2011hr to be M{(}56{Ni})\\=\\1.11+/- 0.43 {M}ȯ . SN 2011hr appears more luminous than SN 1991T at around maximum light, and the absorption features from its intermediate-mass elements (IMEs) are noticeably weaker than those of the latter at similar phases. Spectral modeling suggests that SN 2011hr has IMEs of ∼0.07 {M}ȯ in the outer ejecta, which is much lower than the typical value of normal SNe Ia (i.e., 0.3–0.4 {M}ȯ ) and is also lower than the value of SN 1991T (i.e., ∼0.18 {M}ȯ ). These results indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf progenitor that experienced a more efficient burning process in the explosion. Nevertheless, it is still possible that SN 2011hr may serve as a transitional object connecting the SN 1991T-like SNe Ia with a superluminous subclass like SN 2007if given that the latter also shows very weak IMEs at all phases.

  11. SN Ia archaeology: Searching for the relics of progenitors past

    NASA Astrophysics Data System (ADS)

    Woods, Tyrone E.; Gilfanov, Marat; Clocchiatti, Alejandro; Rest, Armin

    2016-06-01

    Despite the critical role that SNe Ia play in the chemical enrichment of the Universe and their great importance in measuring cosmological distances, we still don't know for certain how they arise. In the canonical form of the ``single-degenerate'' scenario, a white dwarf grows through the nuclear burning of matter accreted at its surface from some companion star. This renders it a hot, luminous object (a supersoft X-ray source or SSS, 10^5-10^6K, 10^{38} erg/s) for up to a million years prior to explosion. Past efforts to directly detect the progenitors of very recent, nearby SNe Ia in archival soft X-ray images have produced only upper limits, and are only constraining assuming progenitors with much higher temperatures than known SSSs. In this talk, I will outline an alternative approach: given that such objects should be strong sources of ionizing radiation, one may instead search the environment surrounding nearby SN Ia remnants for interstellar matter ionized by the progenitor. Such fossil nebulae should extend out to tens of parsecs and linger for roughly the recombination timescale in the ISM, of order 10,000 — 100,000 years. Progress on this front has been hampered by the failure to detect nebulae surrounding most known SSSs using 1m class telescopes in the early 1990s. I will present new benchmark calculations for the emission-line nebulae expected to surround such objects, demonstrating that previous non-detections are entirely consistent with the low ISM densities expected in the vicinity of most SN Ia progenitors (Woods & Gilfanov, 2016). Modern large optical telescopes are now well able to reach the required limiting surface brightness needed to find such faint emission. With this in mind, I will introduce our new narrow-band survey for fossil nebulae surrounding young Magellanic SN Ia remnants and SSSs, already underway using the Magellan Baade telescope (PI: Alejandro Clocchiatti). In addition to opening a new era of SN Ia archaeology, I will show

  12. SN IA in the IR: RAISIN A progress report

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert P.; The RAISIN TEAM

    2014-01-01

    SN Ia have proven to be a powerful tool for cosmology. Near-IR observations of SN Ia promise even better results because the supernovae are more nearly standard candles at those wavelengths and absorption by dust is diminished by a factor of 4 compared to rest-frame B-band observations. Near IR observations of cosmologically-distant SN Ia discovered with PanSTARRS are underway using the infrared camera on the Hubble Space Telescope (GO-13046). These targets are discovered in the difference images created in the CfA/JHU pipeline, confirmed spectroscopically at the MMT, Magellan, Gemini, or Keck, and inserted in a non-disruptive way into the HST observing schedule for WFC3-IR. We have observed over 20 SN Ia in the range 0.2 < z < 0.5 during Cycle 21 and this is a progress report on the analysis. The final results require a repeat observation after the supernova has faded. Those will be completed in 2014, but we have a sufficient sample of objects for which the supernova is well separated from the host galaxy to illustrate the power of this technique. Preliminary analysis shows HST data can reduce the uncertainty in the distance to each supernova by a factor or 2. Sufficiently large supernova samples have been gathered at all redshifts so that statistical errors in interesting parameters (like the dark energy equation-of-state index (1 +w)), have been driven down to the same level as the systematic errors (about 7%). Further progress is limited by our ability to master the systematic errors. These include the correction for luminosity based on the light curve shape and the correction based on intrinsic color and reddening by dust. Since SN IA behave better in the IR in both these ways, there is reason to expect that this approach will be effective in driving down the systematic errors over time. If we are diligent in building up the size of the sample that is observed in the rest-frame infrared, we can expect more certain knowledge of the properties of dark energy

  13. Radio Observations of Type Ia SN2006X

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia

    2006-02-01

    Alicia Soderberg (Caltech) reports: I observed the Type Ia supernova 2006X in NGC 4321 (IAUC 8667, CBET 393) with the Very Large Array on 2006 February 9.34 UT (approximately 2 days after optical discovery). The 2.5 hour observation at 8.46 GHz reveals no radio source coincident with the optical SN position. I place a limit on the radio flux density of 45 microJy (3 sigma). At a distance of 16 Mpc this limit corresponds to a luminosity of 1.4 x 10^25 erg/s/Hz.

  14. Origin of Galactic Type-Ia supernovae: SN 1572 and SN 1006

    NASA Astrophysics Data System (ADS)

    González-Hernández, J. I.; Ruiz-Lapuente, P.; Tabernero, H. M.; Montes, D.; Canal, R.; Méndez, J.; Bedin, L. R.

    2015-05-01

    We have been searching for surviving companions of progenitors of Galactic Type-Ia supernovae, in particular SN 1572 and SN 1006. These companion stars are expected to show peculiarities: (i) to be probably more luminous than the Sun, (ii) to have high radial velocity and proper motion, (iii) to be possibly enriched in metals from the SNIa ejecta, and (iv) to be located at the distance of the SNIa remnant. We have been characterizing possible candidate stars using high-resolution spectroscopic data taken at 10m-Keck and 8.2m-VLT facilities. We have identified a very promising candidate companion (Tycho G) for SN 1572 (see Ruiz-Lapuente et al. 2004; however for a different view see Kerzendorf et al., 2012) but we have not found any candidate companion for SN 1006, suggesting that SN event occurred in 1006 could have been the result of the merging of two white dwarfs (see González-Hernández et al., 2012). Adding these results to the evidence from the other direct searches, the clear minority of cases (20% or less) seem to disfavour the single-degenerate channel or that preferentially the single-degenerate escenario would involve main-sequence companions less massive than the Sun. Therefore, it appears to be very important to continue investigating these and other Galactic Type-Ia SNe such as the Johannes Kepler SN 1604.

  15. Abundance stratification in Type Ia supernovae - V. SN 1986G bridging the gap between normal and subluminous SNe Ia

    NASA Astrophysics Data System (ADS)

    Ashall, C.; Mazzali, P. A.; Pian, E.; James, P. A.

    2016-08-01

    A detailed spectroscopic analysis of SN 1986G has been performed. SN 1986G `bridges the gap' between normal and sub luminous type Ia supernova (SNe Ia). The abundance tomography technique is used to determine the abundance distribution of the elements in the ejecta. SN 1986G was found to be a low energy Chandrasekhar mass explosion. Its kinetic energy was 70% of the standard W7 model (0.9 × 1051 erg). Oxygen dominates the ejecta from the outermost layers down to ˜ 9000 kms-1 , intermediate mass elements (IME) dominate from ˜ 9000 kms-1 to ˜ 3500 kms-1 with Ni and Fe dominating the inner layers <˜ 3500 kms-1. The final masses of the main elements in the ejecta were found to be, O=0.33 M⊙, IME=0.69 M⊙, stable NSE=0.21 M⊙, 56Ni=0.14 M⊙. An upper limit of the carbon mass is set at C=0.02 M⊙. The spectra of SN 1986G consist of almost exclusively singly ionised species. SN 1986G can be thought of as a low luminosity extension of the main population of SN Ia, with a large deflagration phase that produced more IMEs than a standard SN Ia.

  16. Constraints on dark energy with the LOSS SN Ia sample

    NASA Astrophysics Data System (ADS)

    Ganeshalingam, Mohan; Li, Weidong; Filippenko, Alexei V.

    2013-08-01

    We present a cosmological analysis of the Lick Observatory Supernova Search (LOSS) Type Ia supernova (SN Ia) photometry sample introduced by Ganeshalingam et al. These supernovae (SNe) provide an effective anchor point to estimate cosmological parameters when combined with data sets at higher redshift. The data presented by Ganeshalingam et al. have been rereduced in the natural system of the Katzman Automatic Imaging Telescope (KAIT) and Nickel telescopes to minimize systematic uncertainties. We have run the light-curve-fitting software SALT2 on our natural-system light curves to measure light-curve parameters for LOSS light curves and available SN Ia data sets in the literature. We present a Hubble diagram of 586 SNe in the redshift range z = 0.01-1.4 with a residual scatter of 0.176 mag. Of the 226 low-z SNe Ia in our sample, 91 objects are from LOSS, including 45 without previously published distances. Assuming a flat Universe, we find that the best fit for the dark energy equation-of-state parameter w = -0.86^{+0.13}_{-0.16} (stat) ±0.11 (sys) from SNe alone, consistent with a cosmological constant. Our data prefer a Universe with an accelerating rate of expansion with 99.999 per cent confidence. When looking at Hubble residuals as a function of host-galaxy morphology, we do not see evidence for a significant trend, although we find a somewhat reduced scatter in Hubble residuals from SNe residing within a projected distance <10 kpc of the host-galaxy nucleus (σ = 0.156 mag). Similar to the results of Blondin, Mandel and Kirshner and Silverman et al., we find that Hubble residuals do not correlate with the expansion velocity of Si II λ6355 measured in optical spectra near maximum light. Our data are consistent with no presence of a local `Hubble bubble.' Improvements in cosmological analyses within low-z samples can be achieved by better constraining calibration uncertainties in the zero-points of photometric systems.

  17. Photometric type Ia supernova candidates from the three-year SDSS-II SN survey data

    SciTech Connect

    Sako, Masao; Bassett, Bruce; Connolly, Brian; Dilday, Benjamin; Cambell, Heather; Frieman, Joshua A.; Gladney, Larry; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Miquel, Ramon; /Barcelona, IFAE /ICREA, Barcelona /Portsmouth U., ICG

    2011-07-01

    We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with {approx}91% efficiency and with a contamination of {approx}6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only {approx}20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.

  18. Gamma-rays from Type Ia Supernova SN2014J

    NASA Astrophysics Data System (ADS)

    Churazov, E.; Sunyaev, R.; Isern, J.; Bikmaev, I.; Bravo, E.; Chugai, N.; Grebenev, S.; Jean, P.; Knödlseder, J.; Lebrun, F.; Kuulkers, E.

    2015-10-01

    The whole set of INTEGRAL observations of Type Ia supernova SN 2014J, covering the period 19-162 days after the explosion, has been analyzed. For spectral fitting the data are split into early and late periods covering days 19-35 and 50-162, respectively, optimized for 56Ni and 56Co lines. As expected for the early period, much of the gamma-ray signal is confined to energies below ˜200 keV, while for the late period it is strongest above 400 keV. In particular, in the late period, 56Co lines at 847 and 1248 keV are detected at 4.7σ and 4.3σ, respectively. The light curves in several representative energy bands are calculated for the entire period. The resulting spectra and light curves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical one-dimensional models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass white dwarf. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe line profiles, suggesting that, unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.

  19. GAMMA RAYS FROM TYPE Ia SUPERNOVA SN 2014J

    SciTech Connect

    Churazov, E.; Sunyaev, R.; Grebenev, S.; Bikmaev, I.; Bravo, E.; Chugai, N.; Jean, P.; Knödlseder, J.; Lebrun, F.

    2015-10-10

    The whole set of INTEGRAL observations of Type Ia supernova SN 2014J, covering the period 19–162 days after the explosion, has been analyzed. For spectral fitting the data are split into early and late periods covering days 19–35 and 50–162, respectively, optimized for {sup 56}Ni and {sup 56}Co lines. As expected for the early period, much of the gamma-ray signal is confined to energies below ∼200 keV, while for the late period it is strongest above 400 keV. In particular, in the late period, {sup 56}Co lines at 847 and 1248 keV are detected at 4.7σ and 4.3σ, respectively. The light curves in several representative energy bands are calculated for the entire period. The resulting spectra and light curves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical one-dimensional models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass white dwarf. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe line profiles, suggesting that, unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.

  20. The Curious Case of SN 2011dn: Was It A Peculiar Type Ia Supernova?

    NASA Astrophysics Data System (ADS)

    Rachubo, Alisa; Salvo, Chris; Leonard, Douglas C.; Duong, Nhieu; Horst, Chuck; Khandrika, Harish G.; Sumandal, Julienne; Moustakas, John

    2014-06-01

    Type Ia supernovae (SNe Ia) are excellent cosmological distance indicators due to the uniformity in their light curves. This led to the major discovery of the accelerated expansion of the universe (Riess et al. 1998, Perlmutter et al. 1999). However, SNe Ia are not so uniform as one may expect, as there are many ‘peculiar’ SNe Ia that exhibit differences in photometry and spectroscopy from normal SNe Ia. One of the goals of supernova cosmology today is to produce a cleaner sample of SNe Ia by removing the peculiar SNe Ia from the sample. A useful parameter for identifying peculiar SNe Ia based on photometry is Δm15(B), which measures the decrease in B-band magnitude 15 days after the peak of the light curve (Phillips et al. 1993). For typical SNe Ia the standard value is Δm15(B) = 1.1. Peculiar SNe Ia of the overluminous type show a slower decline, with its prototypical member SN 1991T having Δm15(B) = 0.80 (Hicken et al. 2009), while peculiar SNe Ia of the subluminous type show a faster decline, with its prototypical member SN 1991bg having Δm15(B) = 1.87 (Hicken et al. 2009). Here we present optical photometry and spectroscopy of SN 2011dn, which were obtained as part of the MOunt LAguna SUpernova Survey (MOLASUS). Based on its pre-maximum spectrum, which showed strong absorption lines of Fe III λ4404 and Fe III λ5129, along with a weak Si II λ6355 absorption line, SN 2011dn was classified as a SN 1991T-like event (Koff et al. 2011). However, in an earlier preliminary analysis of the light curves - based on point-spread-function photometry - we proposed that SN 2011dn might have had a higher than expected Δm15(B) value of 1.08 (Salvo et al. 2012). Since SN 2011dn is embedded in its host galaxy UGC 11501, it is possible that some of the light from the host galaxy was measured, which may have influenced the measured Δm15(B) value. Here, we employ galaxy-subtraction techniques to isolate the supernova light from its host galaxy, and generate more

  1. The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode As Deflagrations?

    SciTech Connect

    Phillips, M.M.; Li, W.; Frieman, J.A.; Blinnikov, S.I.; DePoy, D.; Prieto, J.L.; Milne, P.; Contreras, C.; Folatelli, Gaston; Morrell, N.; Hamuy, M.; Suntzeff, N.B.; Roth, M.; Gonzalez, S.; Krzeminski, W.; Filippenko, A.V.; Freedman, W.L.; Chornock, R.; Jha, S.; Madore, B.F.; Persson, S.E.; /Las Campanas Observ. /UC, Berkeley, Astron. Dept. /Chicago U., Astron. Astrophys. Ctr. /KICP, Chicago /Fermilab /Moscow, ITEP /Garching, Max Planck Inst. /Ohio State U., Dept. Astron. /Arizona U., Astron. Dept. - Steward Observ. /Chile U., Santiago /Texas A-M /Carnegie Inst. Observ. /KIPAC, Menlo Park /Caltech, IPAC /Notre Dame U. /South African Astron. Observ. /Cape Town U. /Washington U., Seattle, Astron. Dept. /New Mexico State U. /Chicago U., FLASH /Baltimore, Space Telescope Sci.

    2006-11-14

    We present extensive u{prime}g{prime}r{prime}i{prime} BV RIY JHK{sub s} photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002cx, which has been called 'the most peculiar known type Ia supernova'. Both supernovae exhibited high ionization SN 1991T-like pre-maximum spectra, yet low peak luminosities like SN 1991bg. The spectra reveal that SN 2005hk, like SN 2002cx, exhibited expansion velocities that were roughly half those of typical type Ia supernovae. The R and I light curves of both supernovae were also peculiar in not displaying the secondary maximum observed for normal type Ia supernovae. Our Y JH photometry of SN 2005hk reveals the same peculiarity in the near-infrared. By combining our optical and near-infrared photometry of SN 2005hk with published ultraviolet light curves obtained with the Swift satellite, we are able to construct a bolometric light curve from {approx} 10 days before to {approx}60 days after B maximum. The shape and unusually low peak luminosity of this light curve, plus the low expansion velocities and absence of a secondary maximum at red and near-infrared wavelengths, are all in reasonable agreement with model calculations of a 3D deflagration which produces {approx} 0.25 M{sub {circle_dot}} of {sup 56}Ni.

  2. The Detection of a Light Echo from Type Ia SN 2007af in NGC 5584

    NASA Astrophysics Data System (ADS)

    Drozdov, Dina; Leising, M. D.; Milne, P.; Riess, A. G.

    2013-06-01

    We report the discovery of a light echo (LE) at t ~1000 days past maximum from the normal Type Ia supernova (SNe Ia) SN 2007af in the spiral galaxy NGC 5584. The presence of a LE is supported by photometric data and analysis of the images acquired during the Cepheid campaign using the Hubble Space Telescope (HST) Wide Field Camera 3 (Riess et al. 2011). The F350 and F555 images show a distinct ring-like structure with an additional central source. The images, taken months apart, show an evolution of the ring structure, which is consistent with a growing light echo in time. We find an angular radius of the outer echo to be ~0.29'' - 0.36''. Using the Cepheid distance to NGC 5584 of 24 Mpc, we find the dust illuminated by the light echo to be at a distance ~800 pc from the supernova. This rare discovery adds to the select few light echoes found in Type Ia SNe: SN 1572, SN 1991T, SN 1995E, SN 1998bu, and SN 2006X. Light echoes are powerful tools that probe the environment around supernovae, determine dust properties and characteristics, and could provide constraints on the progenitors, which are not fully understood for SN Ia.

  3. Predicting the amount of hydrogen stripped by the SN explosion for SN 2002cx-like SNe Ia

    SciTech Connect

    Liu, Zheng-Wei; Chen, X. F.; Wang, B.; Han, Z. W.; Kromer, M.; Fink, M.; Röpke, F. K.; Pakmor, R.

    2013-12-01

    The most favored progenitor scenarios for Type Ia supernovae (SNe Ia) involve the single-degenerate (SD) scenario and the double-degenerate scenario. The absence of stripped hydrogen (H) in the nebular spectra of SNe Ia challenges the SD progenitor models. Recently, it was shown that pure deflagration explosion models of Chandrasekhar-mass white dwarfs, ignited off-center, reproduce the characteristic observational features of 2002cx-like SNe Ia very well. In this work we predict, for the first time, the amount of stripped H for the off-center, pure deflagration explosions. We find that their low kinetic energies lead to inefficient H mass stripping (≲ 0.01 M {sub ☉}), indicating that the stripped H may be hidden in (observed) late-time spectra of SN 2002cx-like SNe Ia.

  4. Constraining the progenitor of the Type Ia Supernova SN 2012cg

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Wei; Stancliffe, Richard J.

    2016-06-01

    The nature of the progenitors of Type Ia supernovae (SNe Ia) is not yet fully understood. In the single-degenerate (SD) scenario, the collision of the SN ejecta with its companion star is expected to produce detectable ultraviolet emission in the first few days after the SN explosion within certain viewing angles. It was recently found that the B - V colour of the nearby SN Ia SN 2012cg at about 16 d before the maximum B-band brightness was about 0.2 mag bluer than those of other normal SNe Ia, which was reported as the first evidence for excess blue light from the interaction of normal SN Ia ejecta with its companion star. In this work, we compare current observations for SN 2012cg from its pre-explosion phase to the late-time nebular phase with theoretical predictions from binary evolution and population synthesis calculations for a variety of popular progenitor scenarios. We find that a main-sequence donor or a carbon-oxygen white dwarf donor binary system is more likely to be the progenitor of SN 2012cg. However, both scenarios also predict properties which are in contradiction to the observed features of this system. Taking both theoretical and observational uncertainties into account, we suggest that it might be too early to conclude that SN 2012cg was produced from an explosion of a Chandrasekhar-mass white dwarf in the SD scenario. Future observations and improved detailed theoretical modelling are still required to place a more stringent constraint on the progenitor of SN 2012cg.

  5. UV-Optical Observation of Type Ia Supernova SN 2013dy in NGC 7250

    NASA Astrophysics Data System (ADS)

    Zhai, Qian; Zhang, Ju-Jia; Wang, Xiao-Feng; Zhang, Tian-Meng; Liu, Zheng-Wei; Brown, Peter J.; Huang, Fan; Zhao, Xu-Lin; Chang, Liang; Yi, Wei-Min; Wang, Chuan-Jun; Xin, Yu-Xin; Wang, Jian-Guo; Lun, Bao-Li; Zhang, Xi-Liang; Fan, Yu-Feng; Zheng, Xiang-Ming; Bai, Jin-Ming

    2016-05-01

    Extensive and independent observations of Type Ia supernova (SN Ia) SN 2013dy are presented, including a larger set of UBVRI photometry and optical spectra from a few days before the peak brightness to ˜ 200 days after explosion, and ultraviolet (UV) photometry spanning from t ≈ -10 days to t ≈ +15 days refers to the B band maximum. The peak brightness (i.e., MB = -19.65 ± 0.40 mag; Lmax = [1.95 ± 0.55] × 1043 erg s-1) and the mass of synthesized 56Ni (i.e., M(56Ni) = 0.90 ± 0.26 M⊙) are calculated, and they conform to the expectation for an SN Ia with a slow decline rate (i.e., Δm15(B) = 0.90 ± 0.03 mag). However, the near infrared (NIR) brightness of this SN (i.e., MH = -17.33 ± 0.30 mag) is at least 1.0 mag fainter than usual. Besides, spectroscopy classification reveals that SN 2013dy resides on the border of “core normal” and “shallow silicon” subclasses in the Branch et al. classification scheme, or on the border of the “normal velocity” SNe Ia and 91T/99aa-like events in the Wang et al. system. These suggest that SN 2013dy is a slow-declining SN Ia located on the transitional region of nominal spectroscopic subclasses and might not be a typical normal sample of SNe Ia.

  6. CONSTRAINING TYPE Ia SUPERNOVA MODELS: SN 2011fe AS A TEST CASE

    SciTech Connect

    Roepke, F. K.; Seitenzahl, I. R.; Kromer, M.; Taubenberger, S.; Ciaraldi-Schoolmann, F.; Hillebrandt, W.; Benitez-Herrera, S.; Pakmor, R.; Sim, S. A.; Aldering, G.; Childress, M.; Fakhouri, H. K.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Baltay, C.; Buton, C.; Chotard, N.; Copin, Y. [Universite de Lyon, F-69622, Lyon; Universite de Lyon 1, Villeurbanne; CNRS and others

    2012-05-01

    The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia supernova (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations of SN 2011fe can be used to constrain SN Ia explosion scenarios. We base our discussion on three-dimensional simulations of a delayed detonation in a Chandrasekhar-mass white dwarf and of a violent merger of two white dwarfs (WDs)-realizations of explosion models appropriate for two of the most widely discussed progenitor channels that may give rise to SNe Ia. Although both models have their shortcomings in reproducing details of the early and near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory (SNfactory), the overall match with the observations is reasonable. The level of agreement is slightly better for the merger, in particular around maximum, but a clear preference for one model over the other is still not justified. Observations at late epochs, however, hold promise for discriminating the explosion scenarios in a straightforward way, as a nucleosynthesis effect leads to differences in the {sup 55}Co production. SN 2011fe is close enough to be followed sufficiently long to study this effect.

  7. On Type IIn/Ia-CSM supernovae as exemplified by SN 2012ca*

    NASA Astrophysics Data System (ADS)

    Inserra, C.; Fraser, M.; Smartt, S. J.; Benetti, S.; Chen, T.-W.; Childress, M.; Gal-Yam, A.; Howell, D. A.; Kangas, T.; Pignata, G.; Polshaw, J.; Sullivan, M.; Smith, K. W.; Valenti, S.; Young, D. R.; Parker, S.; Seccull, T.; McCrum, M.

    2016-07-01

    We present the complete set of ultra-violet, optical and near-infrared photometry and spectroscopy for SN 2012ca, covering the period from 6 d prior to maximum light, until 531 d after maximum. The spectroscopic time series for SN 2012ca is essentially unchanged over 1.5 yr, and appear to be dominated at all epochs by signatures of interaction with a dense circumstellar medium (CSM) rather than the underlying supernova (SN). SN 2012ca is a member of the set of type of the ambiguous IIn/Ia-CSM SNe, the nature of which have been debated extensively in the literature. The two leading scenarios are either a Type Ia SN exploding within a dense CSM from a non-degenerate, evolved companion, or a core-collapse SN from a massive star. While some members of the population have been unequivocally associated with Type Ia SNe, in other cases the association is less certain. While it is possible that SN 2012ca does arise from a thermonuclear SN, this would require a relatively high (between 20 and 70 per cent) efficiency in converting kinetic energy to optical luminosity, and a massive (˜2.3-2.6 M⊙) circumstellar medium. On the basis of energetics, and the results of simple modelling, we suggest that SN 2012ca is more likely associated with a core-collapse SN. This would imply that the observed set of similar SNe to SN 2012ca is in fact originated by two populations, and while these are drawn from physically distinct channels, they can have observationally similar properties.

  8. Central Elemental Abundance Ratios In the Perseus Cluster: Resonant Scattering or SN Ia Enrichment?

    NASA Technical Reports Server (NTRS)

    Dupke, Renato A.; Arnaud, Keith; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We have determined abundance ratios in the core of the Perseus Cluster for several elements. These ratios indicate a central dominance of Type 1a supernova (SN Ia) ejects similar to that found for A496, A2199 and A3571. Simultaneous analysis of ASCA spectra from SIS1, GIS2, and GIS3 shows that the ratio of Ni to Fe abundances is approx. 3.4 +/- 1.1 times solar within the central 4'. This ratio is consistent with (and more precise than) that observed in other clusters whose central regions are dominated by SN Ia ejecta. Such a large Ni overabundance is predicted by "convective deflagration" explosion models for SNe Ia such as W7 but is inconsistent with delayed detonation models. We note that with current instrumentation the Ni K(alpha) line is confused with Fe K(beta) and that the Ni overabundance we observe has been interpreted by others as an anomalously large ratio of Fe K(beta) to Fe K(alpha) caused by resonant scattering in the Fe K(alpha) line. We argue that a central enhancement of SN Ia ejecta and hence a high ratio of Ni to Fe abundances are naturally explained by scenarios that include the generation of chemical gradients by suppressed SN Ia winds or ram pressure stripping of cluster galaxies. It is not necessary to suppose that the intracluster gas is optically thick to resonant scattering of the Fe K(alpha) line.

  9. Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy Masses

    SciTech Connect

    Kelly, Patrick L.; Hicken, Malcolm; Burke, David L.; Mandel, Kaisey S.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2010-05-03

    From Sloan Digital Sky Survey u{prime} g{prime} r{prime} i{prime} z{prime} imaging, we estimate the stellar masses of the host galaxies of 70 low redshift SN Ia (0.015 < z < 0.08) from the hosts absolute luminosities and mass-to-light ratios. These nearby SN were discovered largely by searches targeting luminous galaxies, and we find that their host galaxies are substantially more massive than the hosts of SN discovered by the flux-limited Supernova Legacy Survey. Testing four separate light curve fitters, we detect {approx}2.5{sigma} correlations of Hubble residuals with both host galaxy size and stellar mass, such that SN Ia occurring in physically larger, more massive hosts are {approx}10% brighter after light curve correction. The Hubble residual is the deviation of the inferred distance modulus to the SN, calculated from its apparent luminosity and light curve properties, away from the expected value at the SN redshift. Marginalizing over linear trends in Hubble residuals with light curve parameters shows that the correlations cannot be attributed to a light curve-dependent calibration error. Combining 180 higher-redshift ESSENCE, SNLS, and HigherZ SN with 30 nearby SN whose host masses are less than 10{sup 10.8} M{circle_dot} n a cosmology fit yields 1 + w = 0.22{sub -0.108}{sup +0.152}, while a combination where the 30 nearby SN instead have host masses greater than 10{sup 10.8} M{circle_dot} yields 1 + w = ?0.03{sub -0.143}{sup +0.217}. Progenitor metallicity, stellar population age, and dust extinction correlate with galaxy mass and may be responsible for these systematic effects. Host galaxy measurements will yield improved distances to SN Ia.

  10. Hubble Space Telescope And Ground-based Observations Of SN 2005hk And SN 2008a: SN 2002cx-like Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    McCully, Curtis; Jha, S. W.; Foley, R. J.; Garnavich, P. M.

    2011-01-01

    Type Ia supernovae (SNe Ia) have been very successful tools for studying the history of cosmic expansion and led to the discovery of the accelerating universe and dark energy. However, the explosion mechanism and progenitors for SNe Ia are still not fundamentally well understood. We present results from late time (up to 600 days past maximum brightness) HST and ground based observations of two typical members of the SN 2002cx-like subclass of peculiar SNe Ia: SN 2005hk and SN 2008A. At late times, these objects are characterized by significant amounts of high density, low velocity material giving a unique opportunity to resolve spectral features that are blended in normal SNe Ia. We identify permitted Fe I and Fe II lines, allowing us to calculate a characteristic temperature, and use the ratio between permitted and forbidden Ca II lines to constrain the density. We find that the density stays extraordinarily high out to late phases, implying enhanced cooling. However, we do not confirm the presence of the "infrared catastrophe” that is generically predicted by SN models as the ejecta cools. We also constrain explosion models for these objects: the lack of [0 I] 6300 A emission allows us to rule out the possibility that these peculiar objects are pure deflagration explosions that leave large amounts of unburned material in the innermost layers of the ejecta. Understanding what makes these SNe so different from their normal cousins has the promise to clarify these key systematic uncertainties in their use for cosmology.

  11. Searching for hidden unexpected features in the SnIa data

    NASA Astrophysics Data System (ADS)

    Shafieloo, A.; Perivolaropoulos, L.

    2010-06-01

    It is known that κ2 statistic and likelihood analysis may not be sensitive to the all features of the data. Despite of the fact that by using κ2 statistic we can measure the overall goodness of fit for a model confronted to a data set, some specific features of the data can stay undetectable. For instance, it has been pointed out that there is an unexpected brightness of the SnIa data at z > 1 in the Union compilation. We quantify this statement by constructing a new statistic, called Binned Normalized Difference (BND) statistic, which is applicable directly on the Type Ia Supernova (SnIa) distance moduli. This statistic is designed to pick up systematic brightness trends of SnIa data points with respect to a best fit cosmological model at high redshifts. According to this statistic there are 2.2%, 5.3% and 12.6% consistency between the Gold06, Union08 and Constitution09 data and spatially flat ΛCDM model when the real data is compared with many realizations of the simulated monte carlo datasets. The corresponding realization probability in the context of a (w0,w1) = (-1.4,2) model is more than 30% for all mentioned datasets indicating a much better consistency for this model with respect to the BND statistic. The unexpected high z brightness of SnIa can be interpreted either as a trend towards more deceleration at high z than expected in the context of ΛCDM or as a statistical fluctuation or finally as a systematic effect perhaps due to a mild SnIa evolution at high z.

  12. SN 2014J at M82 - I. A middle-class Type Ia supernova by all spectroscopic metrics

    NASA Astrophysics Data System (ADS)

    Galbany, L.; Moreno-Raya, M. E.; Ruiz-Lapuente, P.; González Hernández, J. I.; Méndez, J.; Vallely, P.; Baron, E.; Domínguez, I.; Hamuy, M.; López-Sánchez, A. R.; Mollá, M.; Catalán, S.; Cooke, E. A.; Fariña, C.; Génova-Santos, R.; Karjalainen, R.; Lietzen, H.; McCormac, J.; Riddick, F. C.; Rubiño-Martín, J. A.; Skillen, I.; Tudor, V.; Vaduvescu, O.

    2016-03-01

    We present the intensive spectroscopic follow up of the Type Ia supernova (SN Ia) 2014J in the starburst galaxy M82. Twenty-seven optical spectra have been acquired from 2014 January 22 to September 1 with the Isaac Newton and William Herschel Telescopes. After correcting the observations for the recession velocity of M82 and for Milky Way and host galaxy extinction, we measured expansion velocities from spectral line blueshifts and pseudo-equivalent width of the strongest features in the spectra, which gives an idea on how elements are distributed within the ejecta. We position SN 2014J in the Benetti, Branch et al. and Wang et al. diagrams. These diagrams are based on properties of the Si II features and provide dynamical and chemical information about the SN ejecta. The nearby SN 2011fe, which showed little evidence for reddening in its host galaxy, is shown as a reference for comparisons. SN 2014J is a border-line object between the Core-normal and Broad-line groups, which corresponds to an intermediate position between low-velocity gradient and high-velocity gradient objects. SN 2014J follows the R(Si II)-Δm15 correlation, which confirms its classification as a relatively normal SN Ia. Our description of the SN Ia in terms of the evolution of the pseudo-equivalent width of various ions as well as the position in the various diagrams put this specific SN Ia into the overall sample of SN Ia.

  13. Spectroscopic Classification of ASASSN-16gp as a Type Ia SN

    NASA Astrophysics Data System (ADS)

    Strader, Jay; Chomiuk, Laura; Prieto, Jose L.

    2016-07-01

    We obtained an optical spectrum of ASASSN-16gp (ATel #9199) on UT July 6.96 with the Goodman Spectrograph on the SOAR telescope. Classification with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) indicates ASASSN-16gp is a normal Type Ia SN observed at 20-30 days after peak.

  14. EVN measurements show no evidence for radio emission from the Type Ia SN 2014J

    NASA Astrophysics Data System (ADS)

    Perez-Torres, M.; Lundqvist, P.; Paragi, Z.; Bjornsson, C. I.; Fransson, C.; Alberdi, A.; Argo, M. K.; Beswick, R.; Guirado, J. C.; Marcaide, J. M.; Martí-Vidal, I.; Muxlow, T. W. M.; Ros, E.; Ryder, S.; Schmidt, B.

    2014-05-01

    We report deep electronic European VLBI Network (eEVN) radio observations of the Type Ia SN 2014J, which was discovered on 21.8 January 2014, about 6.8 days after its explosion (see http://www.k-itagaki.jp/psn-m82.jpg) in the nearby (D=3.5 Mpc) galaxy NGC 3034 = M82 ...

  15. The dependence of the AV prior for SN Ia on host mass and disc inclination

    NASA Astrophysics Data System (ADS)

    Holwerda, B. W.; Keel, W. C.; Kenworthy, M. A.; Mack, K. J.

    2015-08-01

    Type Ia supernovae (SNe Ia) are used as `standard candles' for cosmological distance scales. To fit their light-curve shape-absolute luminosity relation, one needs to assume an intrinsic colour and a likelihood of host galaxy extinction or a convolution of these, a colour distribution prior. The host galaxy extinction prior is typically assumed to be an exponential drop-off for the current supernova programmes (P(A_V) ∝ e^{-A_V/τ_0}). We explore the validity of this prior using the distribution of extinction values inferred when two galaxies accidentally overlap (an occulting galaxy pair). We correct the supernova luminosity distances from the SDSS-III supernova projects (SDSS-SN) by matching the host galaxies to one of three templates from occulting galaxy pairs based on the host galaxy mass and the AV-bias-prior-scale (τ0) relation from Jha et al. We find that introducing an AV prior that depends on host mass results in lowered luminosity distances for the SDSS-SN on average but it does not reduce the scatter in individual measurements. This points, in our view, to the need for many more occulting galaxy templates to match to SN Ia host galaxies to rule out this possible source of scatter in the SN Ia distance measurements. We match occulting galaxy templates based on both mass and projected radius and we find that one should match by stellar mass first with radius as a secondary consideration. We discuss the caveats of the current approach: the lack of enough radial coverage, the small sample of priors (occulting pairs with HST data), the effect of gravitationally interacting as well as occulting pairs, and whether an exponential distribution is appropriate. Our aim is to convince the reader that a library of occulting galaxy pairs observed with HST will provide sufficient priors to improve (optical) SN Ia measurements to the next required accuracy in cosmology.

  16. Power-law cosmology, SN Ia, and BAO

    SciTech Connect

    Dolgov, Aleksander; Halenka, Vitali; Tkachev, Igor E-mail: vithal@umich.edu

    2014-10-01

    We revise observational constraints on the class of models of modified gravity which at low redshifts lead to a power-law cosmology. To this end we use available public data on Supernova Ia and on baryon acoustic oscillations. We show that the expansion regime a(t) ∼ t{sup β} with β close to 3/2 in a spatially flat universe is a good fit to these data.

  17. SN 2010LP—A TYPE IA SUPERNOVA FROM A VIOLENT MERGER OF TWO CARBON-OXYGEN WHITE DWARFS

    SciTech Connect

    Kromer, M.; Taubenberger, S.; Seitenzahl, I. R.; Hillebrandt, W.; Pakmor, R.; Pignata, G.; Fink, M.; Röpke, F. K.; Sim, S. A.

    2013-11-20

    SN 2010lp is a subluminous Type Ia supernova (SN Ia) with slowly evolving lightcurves. Moreover, it is the only subluminous SN Ia observed so far that shows narrow emission lines of [O I] in late-time spectra, indicating unburned oxygen close to the center of the ejecta. Most explosion models for SNe Ia cannot explain the narrow [O I] emission. Here, we present hydrodynamic explosion and radiative transfer calculations showing that the violent merger of two carbon-oxygen white dwarfs of 0.9 and 0.76 M {sub ☉} adequately reproduces the early-time observables of SN 2010lp. Moreover, our model predicts oxygen close to the center of the explosion ejecta, a pre-requisite for narrow [O I] emission in nebular spectra as observed in SN 2010lp.

  18. Gamma-Ray Line Flux Ratios as Diagnostics of SN Ia Models

    NASA Astrophysics Data System (ADS)

    Lara, Juan; The, Lih-Sin; Leising, Mark

    2004-05-01

    The ^56Ni decay chain that powers the optical output of Type Ia supernovae produces gamma-ray lines at 158, 812 ( ^56Ni decay ) and 847, 1238 keV ( ^56Co decay ). The detection of the line fluxes have been used to show indeed that ^56Ni is produced by explosive nucleosynthesis. We investigate the measurement precision required to use the flux ratios of these lines to each other and to the compton X-ray continuum to distinguish among a variety of SN Ia models. We compare this to using gamma-ray line profiles to distinguish among models.

  19. Rotating Type Ia SN progenitors: explosion and light curves

    SciTech Connect

    Dominguez, I.; Piersanti, L.; Gagliardi, S.; Straniero, O.; Tornambe, A.; Bravo, E.

    2005-10-21

    High redshift SNe Ia have been recently used to calibrate the cosmological distance scale and to infer the existence of the dark energy. The reliability of such a method depends on the effective knowledge of the absolute brightness of this class of supernovae. This would require a complete understanding of the physics of SNeIa.Starting from an accreting rotating white dwarf, the only progenitor that we found to be able to grow till the Chandrasekhar mass and undergo a thermonuclear explosion, we simulate the explosion, deriving the nucleosynthesis and the light curve. We explore the final outcome in the framework of a 1D delayed detonation model, where the characteristic density for which the transition from deflagration to detonation takes place is a free parameter.Although preliminary, our results imply that rotating white dwarfs produce a range of explosive conditions, characterized by different ignition densities and total masses. Maximum luminosities of successfully explosive models differ up to 0.11 mag. In a few cases, the formation of a small highly neutronised remnant is found.

  20. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  1. SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-degenerate Binary Companion

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Brown, Peter J.; Vinkó, Jozsef; Silverman, Jeffrey M.; Sand, David J.; Challis, Peter; Kirshner, Robert P.; Wheeler, J. Craig; Berlind, Perry; Brown, Warren R.; Calkins, Michael L.; Camacho, Yssavo; Dhungana, Govinda; Foley, Ryan J.; Friedman, Andrew S.; Graham, Melissa L.; Howell, D. Andrew; Hsiao, Eric Y.; Irwin, Jonathan M.; Jha, Saurabh W.; Kehoe, Robert; Macri, Lucas M.; Maeda, Keiichi; Mandel, Kaisey; McCully, Curtis; Pandya, Viraj; Rines, Kenneth J.; Wilhelmy, Steven; Zheng, Weikang

    2016-04-01

    We report evidence for excess blue light from the Type Ia supernova (Sn Ia) SN 2012cg at 15 and 16 days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a normal SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected {M}B=-19.62+/- 0.02 mag and {{Δ }}{m}15(B)=0.86+/- 0.02. Our data set is extensive, with photometry in seven filters from five independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity vSi = -10,500 km s-1. Comparing the early data with models by Kasen favors a main-sequence companion of about six solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.

  2. Low mass SN Ia and the late light curve

    SciTech Connect

    Colgate, S.A.; Fryer, C.L.; Hand, K.P.

    1995-12-31

    The late bolometric light curves of type Ia supernovae, when measured accurately over several years, show an exponential decay with a 56d half-life over a drop in luminosity of 8 magnitudes (10 half-lives). The late-time light curve is thought to be governed by the decay of Co{sup 56}, whose 77d half-life must then be modified to account for the observed decay time. Two mechanisms, both relying upon the positron fraction of the Co{sup 56} decay, have been proposed to explain this modification. One explanation requires a large amount of emission at infra-red wavelengths where it would not be detected. The other explanation has proposed a progressive transparency or leakage of the high energy positrons (Colgate, Petschek and Kriese, 1980). For the positrons to leak out of the expanding nebula at the required rate necessary to produce the modified 56d exponential, the mass of the ejecta from a one foe (10{sup 51} erg in kinetic energy) explosion must be small, M{sub ejec} = 0.4M{sub {circle_dot}} with M{sub ejec} {proportional_to} KE{sup 0.5}. Thus, in this leakage explanation, any reasonable estimate of the total energy of the explosion requires that the ejected mass be very much less than the Chandrasekhar mass of 1.4M{sub {circle_dot}}. This is very difficult to explain with the ``canonical`` Chandrasekhar-mass thermonuclear explosion that disintegrates the original white dwarf star. This result leads us to pursue alternate mechanisms of type Ia supernovae. These mechanisms include sub-Chandrasekhar thermonuclear explosions and the accretion induced collapse of Chandrasekhar mass white dwarfs. We will summarize the advantages and disadvantages of both mechanisms with considerable detail spent on our new accretion induced collapse simulations. These mechanisms lead to lower Ni{sup 56} production and hence result in type Ia supernovae with luminosities decreased down to {approximately} 50% that predicted by the ``standard`` model.

  3. Discovery of Cepheids in NGC 5253: Absolute peak brightness of SN Ia 1895B and SN Ia 1972E and the value of H(sub 0)

    NASA Technical Reports Server (NTRS)

    Saha, A.; Sandage, Allan; Labhardt, Lukas; Schwengeler, Hans; Tammann, G. A.; Panagia, N.; Macchetto, F. D.

    1995-01-01

    Observations of the Hubble Space Telescope (HST) between 1993 May 31 and 1993 July 19 in 20 epochs in the F555W passband and five epochs in the F785LP passband have led to the discovery of 14 Cepheids in the Amorphous galaxy NGC 5253. The apparent V distance modulus is (m-M)(sub AV) = 28.08 +/- 0.10 determined from the 12 Cepheids with normal amplitudes. The distance modulus using the F785LP data is consistent with the V value to within the errors. Five methods used to determine the internal reddening are consistent with zero differential reddening, accurate to a level of E(B-V) less than 0.05 mag, over the region occupied by Cepheids and the two supernovae (SNe) produced by NGC 5253. The apparent magnitudes at maximum for the two SNe in NGC 5253 are adopted as B(sub max) = 8.33 +/- 0.2 mag for SN 1895B, and B(sub max) = 8.56 +/- 0.1 and V(sub max) = 8.60 +/- 0.1 for SN 1972E which is a prototype SN of Type Ia. The apparent magnitude system used by Walker (1923) for SN 1859B has been corrected to the modern B scale and zero point to determine its adopted B(sub max) value.

  4. Spectroscopic Observations and Analysis of the Unusual Type Ia SN1999ac

    SciTech Connect

    Garavini, G.; Aldering, G.; Amadon, A.; Amanullah, R.; Astier,P.; Balland, C.; Blanc, G.; Conley, A.; Dahlen, T.; Deustua, S.E.; Ellis,R.; Fabbro, S.; Fadeyev, V.; Fan, X.; Folatelli, G.; Frye, B.; Gates,E.L.; Gibbons, R.; Goldhaber, G.; Goldman, B.; Goobar, A.; Groom, D.E.; Haissinski, J.; Hardin, D.; Hook, I.; Howell, D.A.; Kent, S.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Kuznetsova, N.; Lee, B.C.; Lidman, C.; Mendez,J.; Miller, G.J.; Moniez, M.; Mouchet, M.; Mourao, A.; Newberg, H.; Nobili, S.; Nugent, P.E.; Pain, R.; Perdereau, O.; Perlmutter, S.; Quimby, R.; Regnault, N.; Rich, J.; Richards, G.T.; Ruiz-Lapuente, P.; Schaefer, B.E.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Stanishev,V.; Thomas, R.C.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.

    2005-07-12

    The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.

  5. Tycho SN 1572: A Naked Ia Supernova Remnant Without an Associated Ambient Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Tian, W. W.; Leahy, D. A.

    2011-03-01

    The historical supernova remnant (SNR) Tycho SN 1572 originates from the explosion of a normal Type Ia supernova that is believed to have originated from a carbon-oxygen white dwarf in a binary system. We analyze the 21 cm continuum, H I, and 12CO-line data from the Canadian Galactic Plane Survey in the direction of SN 1572 and the surrounding region. We construct H I absorption spectra to SN 1572 and three nearby compact sources. We conclude that SN 1572 has no molecular cloud interaction, which argues against previous claims that a molecular cloud is interacting with the SNR. This new result does not support a recent claim that dust, newly detected by AKARI, originates from such an SNR-cloud interaction. We suggest that the SNR has a kinematic distance of 2.5-3.0 kpc based on a nonlinear rotational curve model. Very high energy γ-ray emission from the remnant has been detected by the VERITAS telescope, so our result shows that its origin should not be an SNR-cloud interaction. Both radio and X-ray observations support that SN 1572 is an isolated Type Ia SNR.

  6. TYCHO SN 1572: A NAKED Ia SUPERNOVA REMNANT WITHOUT AN ASSOCIATED AMBIENT MOLECULAR CLOUD

    SciTech Connect

    Tian, W. W.; Leahy, D. A.

    2011-03-10

    The historical supernova remnant (SNR) Tycho SN 1572 originates from the explosion of a normal Type Ia supernova that is believed to have originated from a carbon-oxygen white dwarf in a binary system. We analyze the 21 cm continuum, H I, and {sup 12}CO-line data from the Canadian Galactic Plane Survey in the direction of SN 1572 and the surrounding region. We construct H I absorption spectra to SN 1572 and three nearby compact sources. We conclude that SN 1572 has no molecular cloud interaction, which argues against previous claims that a molecular cloud is interacting with the SNR. This new result does not support a recent claim that dust, newly detected by AKARI, originates from such an SNR-cloud interaction. We suggest that the SNR has a kinematic distance of 2.5-3.0 kpc based on a nonlinear rotational curve model. Very high energy {gamma}-ray emission from the remnant has been detected by the VERITAS telescope, so our result shows that its origin should not be an SNR-cloud interaction. Both radio and X-ray observations support that SN 1572 is an isolated Type Ia SNR.

  7. SPECTROPOLARIMETRY OF THE TYPE Ia SN 2007sr TWO MONTHS AFTER MAXIMUM LIGHT

    SciTech Connect

    Zelaya, P.; Quinn, J. R.; Clocchiatti, A.; Baade, D.; Patat, F.; Hoeflich, P.; Maund, J.; Wang, L.; Wheeler, J. C.

    2013-02-01

    We present late-time spectropolarimetric observations of SN 2007sr, obtained with the Very Large Telescope at the ESO Paranal Observatory when the object was 63 days after maximum light. The late-time spectrum displays strong line polarization in the Ca II absorption features. SN 2007sr adds to the case of some normal Type Ia supernovae that show high line polarization or repolarization at late times, a fact that might be connected with the presence of high-velocity features at early times.

  8. Supernova Emulators: Connecting Massively Parallel SN Ia Radiative Transfer Simulations to Data with Gaussian Processes

    NASA Astrophysics Data System (ADS)

    Goldstein, Daniel; Thomas, Rollin; Kasen, Daniel

    2015-01-01

    Collaboration between the type Ia supernova (SN Ia) modeling and observation communities hinges on our ability to directly connect simulations to data. Here we introduce supernova emulation, a method for facilitating such a connection. Emulation allows us to instantaneously predict the observables (light curves, spectra, spectral time series) generated by arbitrary SN Ia radiative transfer simulations, with estimates of prediction error. Emulators learn the mapping between physically meaningful simulation inputs and the resulting synthetic observables from a training set of simulation input-output pairs. In our emulation framework, we model PCA-decomposed representations of simulated observables as an ensemble of Gaussian Processes. As a proof of concept, we train a bolometric light curve (BLC) emulator on a grid of 400 simulation inputs and BLCs synthesized with the publicly available, gray, time-dependent Monte Carlo expanding atmospheres code, SMOKE. We emulate SMOKE simulations evaluated at a set of 100 out-of-sample input parameters, and achieve excellent agreement between the emulator predictions and the simulated BLCs. In addition to predicting simulation outputs, emulators allow us to infer the regions of simulation input parameter space that correspond to observed SN Ia light curves and spectra. We present a Bayesian framework for solving this inverse problem using Markov Chain Monte Carlo sampling. We fit published bolometric light curves with our emulator and obtain reconstructed masses (nickel mass, total ejecta mass) in agreement with reconstructions from semi-analytic models. We discuss applications of emulation to supernova cosmology and physics, including how emulators can be used to identify and quantify astrophysical sources of systematic error affecting SNe Ia as distance indicators for cosmology.

  9. FLOYDS Classification of ASASSN-14jg as a Type Ia SN Near Peak

    NASA Astrophysics Data System (ADS)

    Arcavi, Iair; Valenti, Stefano; Hosseinzadeh, Griffin; McCully, Curtis; Howell, D. Andrew

    2014-11-01

    We obtained a spectrum of ASASSN-14jg (ATel #6637) on 2014 November 2 (UT) with the robotic FLOYDS instrument mounted on the Faulkes Telescope South. Using Superfit (Howell et al. 2005, ApJ 634, 1190) we find a good fit to the Type Ia SN 1999aa near peak at the redshift of the proposed host galaxy (z=0.0148; via NED).

  10. Application of Bayesian graphs to SN Ia data analysis and compression

    NASA Astrophysics Data System (ADS)

    Ma, Cong; Corasaniti, Pier-Stefano; Bassett, Bruce A.

    2016-08-01

    Bayesian graphical models are an efficient tool for modelling complex data and derive self-consistent expressions of the posterior distribution of model parameters. We apply Bayesian graphs to perform statistical analyses of Type Ia supernova (SN Ia) luminosity distance measurements from the Joint Light-curve Analysis (JLA) dataset (Betoule et al. 2014). In contrast to the χ2 approach used in previous studies, the Bayesian inference allows us to fully account for the standard-candle parameter dependence of the data covariance matrix. Comparing with χ2 analysis results we find a systematic offset of the marginal model parameter bounds. We demonstrate that the bias is statistically significant in the case of the SN Ia standardization parameters with a maximal 6σ shift of the SN light-curve colour correction. In addition, we find that the evidence for a host galaxy correction is now only 2.4σ. Systematic offsets on the cosmological parameters remain small, but may increase by combining constraints from complementary cosmological probes. The bias of the χ2 analysis is due to neglecting the parameter-dependent log-determinant of the data covariance, which gives more statistical weight to larger values of the standardization parameters. We find a similar effect on compressed distance modulus data. To this end we implement a fully consistent compression method of the JLA dataset that uses a Gaussian approximation of the posterior distribution for fast generation of compressed data. Overall, the results of our analysis emphasize the need for a fully consistent Bayesian statistical approach in the analysis of future large SN Ia datasets.

  11. Spectroscopic Classification of ASASSN-16cu as a Type Ia SN

    NASA Astrophysics Data System (ADS)

    Strader, Jay; Chomiuk, Laura; Shishkovsky, Laura

    2016-03-01

    We obtained an optical spectrum of ASASSN-16cu (ATel #8796) on UT March 29.37 with the Goodman Spectrograph on the SOAR telescope. Classification with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) indicates ASASSN-16cu is a normal Type Ia SN observed at about 70 days after peak. The redshift is consistent with proposed host galaxy IC 4723 (z=0.011128, via NED).

  12. Late-time Photometry of Type Ia Supernova SN 2012cg Reveals the Radioactive Decay of 57 Co

    NASA Astrophysics Data System (ADS)

    Graur, Or; Zurek, David; Shara, Michael M.; Riess, Adam G.; Seitenzahl, Ivo R.; Rest, Armin

    2016-03-01

    Seitenzahl et al. have predicted that roughly three years after its explosion, the light we receive from a Type Ia supernova (SN Ia) will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain 57Co → 57Fe, instead of positrons from the decay chain 56Co → 56Fe that dominates the SN light at earlier times. Using the Hubble Space Telescope, we followed the light curve of the SN Ia SN 2012cg out to 1055 days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of 57Co, offering evidence that 57Co is produced in SN Ia explosions. However, the data are also consistent with a light echo ∼14 mag fainter than SN 2012cg at peak. Assuming no light-echo contamination, the mass ratio of 57Ni and 56Ni produced by the explosion, a strong constraint on any SN Ia explosion models, is {0.043}-0.011+0.012, roughly twice Solar. In the context of current explosion models, this value favors a progenitor white dwarf with a mass near the Chandrasekhar limit.

  13. What is the progenitor of the Type Ia SN 2014J?

    NASA Astrophysics Data System (ADS)

    Pérez-Torres, M. A.; Lundqvist, P.; Beswick, R. J.; Björnsson, C. I.; Muxlow, T. W. B.; Paragi, Z.; Ryder, S.; Alberdi, A.; Fransson, C.; Marcaide, J. M. M.; Martí-Vidal, I.; Ros, E.; Argo, M. K.; Guirado, J. C.

    2015-05-01

    We report the deepest radio interferometric observations of the closest Type Ia supernova in decades, SN 2014J, which exploded in the nearby galaxy M 82. These observations represent, together with radio observations of SNe 2011fe, the most sensitive radio studies of a Type Ia SN ever. We constrain the mass-loss rate from the progenitor system of SN 2014J to dot{M} ≲ 7.0EE{-10} msunyr (for a wind speed of 100 kms). Our deep upper limits favor a double-degenerate scenario-involving two WD stars-for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. By contrast, most single-degenerate scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to a exploding white dwarf, are ruled out by our observations. The evidence from SNe 2011fe and 2014J points in the direction of a double-degenerate scenario for both.

  14. Preliminary NIR Late Light Curve of the Type Ia Supernova SN2009nr

    NASA Astrophysics Data System (ADS)

    Heath, Jonathan; Bryngelson, G.

    2013-01-01

    Type Ia supernovae (SNe Ia) are important in determining the expansion of the universe based on the uniformity of their light curves. It is essential to understand the behavior of these supernovae in order to strengthen our confidence in their use as standard candles. A small, but increasing number of SNe Ia have been observed later than the 200 day epoch in the near-infrared (NIR). Most of these exhibit a flattening of the NIR power, even as the visible light declines at a steady rate. It is unclear as to exactly what causes this behavior, and how typical it is. In order to characterize the late behavior of SNe Ia, images of the supernova SN2009nr were analyzed using the Image Reduction and Analysis Facility (IRAF). These images were taken with the 4m Mayall Telescope at Kitt Peak National-Observatory using the FLAMINGOS IR Imaging Spectrometer. The supernova’s magnitude was normalized with respect to the magnitudes of known stars so that traits related to the supernova may be compared to others. We present preliminary NIR (J, H, K) light curves of the observed supernova and compare them to other SNe Ia observed at these epochs.

  15. Bright high z SnIa: A challenge for {lambda}CDM

    SciTech Connect

    Perivolaropoulos, L.; Shafieloo, A.

    2009-06-15

    It has recently been pointed out by Kowalski et. al.[Astrophys. J. 686, 749 (2008).] that there is 'an unexpected brightness of the SnIa data at z>1'. We quantify this statement by constructing a new statistic which is applicable directly on the type Ia supernova (SnIa) distance moduli. This statistic is designed to pick up systematic brightness trends of SnIa data points with respect to a best fit cosmological model at high redshifts. It is based on binning the normalized differences between the SnIa distance moduli and the corresponding best fit values in the context of a specific cosmological model (e.g. {lambda}CDM). These differences are normalized by the standard errors of the observed distance moduli. We then focus on the highest redshift bin and extend its size toward lower redshifts until the binned normalized difference (BND) changes sign (crosses 0) at a redshift z{sub c} (bin size N{sub c}). The bin size N{sub c} of this crossing (the statistical variable) is then compared with the corresponding crossing bin size N{sub mc} for Monte Carlo data realizations based on the best fit model. We find that the crossing bin size N{sub c} obtained from the Union08 and Gold06 data with respect to the best fit {lambda}CDM model is anomalously large compared to N{sub mc} of the corresponding Monte Carlo data sets obtained from the best fit {lambda}CDM in each case. In particular, only 2.2% of the Monte Carlo {lambda}CDM data sets are consistent with the Gold06 value of N{sub c} while the corresponding probability for the Union08 value of N{sub c} is 5.3%. Thus, according to this statistic, the probability that the high redshift brightness bias of the Union08 and Gold06 data sets is realized in the context of a (w{sub 0},w{sub 1})=(-1,0) model ({lambda}CDM cosmology) is less than 6%. The corresponding realization probability in the context of a (w{sub 0},w{sub 1})=(-1.4,2) model is more than 30% for both the Union08 and the Gold06 data sets indicating a much better

  16. Optical and ultraviolet observations of the narrow-lined type Ia SN 2012fr in NGC 1365

    SciTech Connect

    Zhang, Ju-Jia; Bai, Jin-Ming; Wang, Bo; Liu, Zheng-Wei; Wang, Xiao-Feng; Zhao, Xu-Lin; Chen, Jun-Cheng; Zhang, Tian-Meng E-mail: baijinming@ynao.ac.cn

    2014-07-01

    Extensive optical and ultraviolet (UV) observations of the type Ia supernova (SN Ia) 2012fr are presented in this paper. It has a relatively high luminosity, with an absolute B-band peak magnitude of about –19.5 mag and a smaller post-maximum decline rate than normal SNe Ia (e.g., Δm {sub 15}(B) =0.85 ± 0.05 mag). Based on the UV and optical light curves, we derived that a {sup 56}Ni mass of about 0.88 M {sub ☉} was synthesized in the explosion. The earlier spectra are characterized by noticeable high-velocity features of Si II λ6355 and Ca II with velocities in the range of ∼22, 000-25, 000 km s{sup –1}. At around the maximum light, these spectral features are dominated by the photospheric components which are noticeably narrower than normal SNe Ia. The post-maximum velocity of the photosphere remains almost constant at ∼12,000 km s{sup –1} for about one month, reminiscent of the behavior of some luminous SNe Ia like SN 1991T. We propose that SN 2012fr may represent a subset of the SN 1991T-like SNe Ia viewed in a direction with a clumpy or shell-like structure of ejecta, in terms of a significant level of polarization reported in Maund et al. in 2013.

  17. 5.0 GHz Continuum MERLIN Observations of the Type Ia SN 2013dy

    NASA Astrophysics Data System (ADS)

    Perez-Torres, M.; Argo, M.; Lundqvist, P.; Anderson, G.; Beswick, R.; Bjornsson, C. I.; Fender, R.; Rushton, A.; Ryder, S.; Staley, T.

    2013-12-01

    We report MERLIN radio observations of the Type Ia supernova 2013dy, which was discovered on 10.45 July 2013, shortly after its explosion, in the nearby (D=13.5 Mpc) galaxy NGC 7250 (cf. CBET #3588). Our observations were carried out during 4 - 6 August 2013, one week after the SN reached its B-band maximum (Zheng et al. 2013). The radio telescopes that participated in the observations included five eMERLIN antennas (Jodrell Mk2, Pickmere, Darnhall, Knockin, and Defford).

  18. Type-Ia SN 2016coj - limits on progenitors from pre-explosion HST images

    NASA Astrophysics Data System (ADS)

    Friedmann, Matan; Maoz, Dan

    2016-07-01

    We have analyzed archival Hubble Space Telescope WFPC2 images of the site of the Type-Ia SN2016coj (ATEL#9095, #9193) in NGC 4125 in five filters taken on several pre-explosion epochs: F336W from 2009 (~U band, 6600 s total), F439W from 2009 (~B band, 2100 s total), F555W from 1999 (~V band, 1400 s total), F702W from 1997 (~R band, 1000 s total) and F814W (~I band, 2000 s total).

  19. EARLY OBSERVATIONS AND ANALYSIS OF THE TYPE Ia SN 2014J IN M82

    SciTech Connect

    Marion, G. H.; Vinkó, J.; Sand, D. J.; Hsiao, E. Y.; Banerjee, D. P. K.; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Valenti, S.; Howell, D. A.; Stritzinger, M. D.; Amanullah, R.; Johansson, J.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, C. R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; and others

    2015-01-01

    We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (–10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from –10d to +29d, in the UBVRIJH and K{sub s} bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R{sub V} = 1.46, which is consistent with previous studies, SNooPy finds that A{sub V} = 1.80 for E(B – V){sub host} = 1.23 ± 0.06 mag. The maximum B-band brightness of –19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, Δm {sub 15}, of 1.12 ± 0.02 mag.

  20. Early Observations and Analysis of the Type Ia SN 2014J in M82

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Sand, D. J.; Hsiao, E. Y.; Banerjee, D. P. K.; Valenti, S.; Stritzinger, M. D.; Vinkó, J.; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Amanullah, R.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, C. R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; Howell, D. A.; Johansson, J.; Kirshner, R. P.; Milne, P. A.; Parrent, J.; Silverman, J. M.; Vervack, R. J., Jr.; Wheeler, J. C.

    2015-01-01

    We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (-10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I λ1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from -10d to +29d, in the UBVRIJH and Ks bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using RV = 1.46, which is consistent with previous studies, SNooPy finds that AV = 1.80 for E(B - V)host = 1.23 ± 0.06 mag. The maximum B-band brightness of -19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, Δm 15, of 1.12 ± 0.02 mag.

  1. On the nature of Type IIn/Ia-CSM supernovae: optical and near-infrared spectra of SN 2012ca and SN 2013dn

    NASA Astrophysics Data System (ADS)

    Fox, Ori D.; Silverman, Jeffrey M.; Filippenko, Alexei V.; Mauerhan, Jon; Becker, Juliette; Borish, H. Jacob; Cenko, S. Bradley; Clubb, Kelsey I.; Graham, Melissa; Hsiao, Eric; Kelly, Patrick L.; Lee, William H.; Marion, G. H.; Milisavljevic, Dan; Parrent, Jerod; Shivvers, Isaac; Skrutskie, Michael; Smith, Nathan; Wilson, John; Zheng, Weikang

    2015-02-01

    A growing subset of Type Ia supernovae (SNe Ia) shows evidence via narrow emission lines for unexpected interaction with a dense circumstellar medium (SNe IIn/Ia-CSM). The precise nature of the progenitor, however, remains debated owing to spectral ambiguities arising from a strong contribution from the CSM interaction. Late-time spectra offer potential insight if the post-shock cold, dense shell becomes sufficiently thin and/or the ejecta begin to cross the reverse shock. To date, only a few high-quality spectra of this kind exist. Here we report on the late-time optical and infrared spectra of the SNe Ia-CSM 2012ca and 2013dn. These SNe Ia-CSM spectra exhibit low [Fe III]/[Fe II] ratios and strong [Ca II] at late epochs. Such characteristics are reminiscent of the super-Chandrasekhar-mass candidate SN 2009dc, for which these features suggested a low-ionization state due to high densities, although the broad Fe features admittedly show similarities to the blue `quasi-continuum' observed in some core collapse SNe Ibn and IIn. Neither SN 2012ca nor any of the other SNe Ia-CSM in this paper show evidence for broad oxygen, carbon, or magnesium in their spectra. Similar to the interacting Type IIn SN 2005ip, a number of high-ionization lines are identified in SN 2012ca, including [S III], [Ar III], [Ar X], [Fe VIII], [Fe X], and possibly [Fe XI]. The total bolometric energy output does not exceed 1051 erg, but does require a large kinetic-to-radiative conversion efficiency. All of these observations taken together suggest that SNe Ia-CSM are more consistent with a thermonuclear explosion than a core collapse event, although detailed radiative transfer models are certainly necessary to confirm these results.

  2. Nebular spectra and abundance tomography of the Type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core

    NASA Astrophysics Data System (ADS)

    Mazzali, P. A.; Sullivan, M.; Filippenko, A. V.; Garnavich, P. M.; Clubb, K. I.; Maguire, K.; Pan, Y.-C.; Shappee, B.; Silverman, J. M.; Benetti, S.; Hachinger, S.; Nomoto, K.; Pian, E.

    2015-07-01

    A series of optical and one near-infrared nebular spectra covering the first year of the Type Ia supernova SN 2011fe are presented and modelled. The density profile that proved best for the early optical/ultraviolet spectra, `ρ-11fe', was extended to lower velocities to include the regions that emit at nebular epochs. Model ρ-11fe is intermediate between the fast deflagration model W7 and a low-energy delayed-detonation. Good fits to the nebular spectra are obtained if the innermost ejecta are dominated by neutron-rich, stable Fe-group species, which contribute to cooling but not to heating. The correct thermal balance can thus be reached for the strongest [Fe II] and [Fe III] lines to be reproduced with the observed ratio. The 56Ni mass thus obtained is ˜0.47 ± 0.05 M⊙. The bulk of 56Ni has an outermost velocity of ˜8500 km s-1. The mass of stable iron is ˜0.23 ± 0.03 M⊙. Stable Ni has low abundance, ˜10-2 M⊙. This is sufficient to reproduce an observed emission line near 7400 Å. A sub-Chandrasekhar explosion model with mass 1.02 M⊙ and no central stable Fe does not reproduce the observed line ratios. A mock model where neutron-rich Fe-group species are located above 56Ni following recent suggestions is also shown to yield spectra that are less compatible with the observations. The densities and abundances in the inner layers obtained from the nebular analysis, combined with those of the outer layers previously obtained, are used to compute a synthetic bolometric light curve, which compares favourably with the light curve of SN 2011fe.

  3. Type Ia Supernovae and Their Environment:Theory and Applications to SN 2014J

    NASA Astrophysics Data System (ADS)

    Dragulin, Paul; Hoeflich, Peter

    2016-02-01

    We present theoretical semi-analytic models for the interaction of stellar winds with the interstellar medium (ISM) or prior mass loss implemented in our code SPICE, assuming spherical symmetry and power-law ambient density profiles and using the Π-theorem. This allows us to test a wide variety of configurations, their functional dependencies, and to find classes of solutions for given observations. Here, we study Type Ia Supernova (SN Ia) surroundings of single and double degenerate systems, and their observational signatures. Winds may originate from the progenitor prior to the white dwarf (WD) stage, the WD, a donor star, or an accretion disk (AD). For MCh explosions, the AD wind dominates and produces a low-density void several light years across, surrounded by a dense shell. The bubble explains the lack of observed interaction in late time SN light curves for, at least, several years. The shell produces narrow ISM lines Doppler shifted by 10-100 km s-1, and equivalent widths of ≈100 mÅ and ≈1 mÅ in cases of ambient environments with constant density and produced by prior mass loss, respectively. For SN2014J, both mergers and MCh mass explosions have been suggested based on radio and narrow lines. As a consistent and most likely solution, we find an AD wind running into an environment produced by the red giant wind of the progenitor during the pre-WD stage, and a short delay, 0.013-1.4 Myr, between the WD formation and the explosion. Our framework may be applied more generally to stellar winds and star formation feedback in large scale galactic evolution simulations.

  4. SALT spectroscopic classification of PS16atu (SN 2016atv) as a type-Ia supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of PS16atu (SN 2016atv) on 2016 Mar 10.1 UT, covering the wavelength range 350-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS16atu is a type-Ia supernova approximately a week past maximum light.

  5. Nearby Supernova Factory Observations of SN 2006D: On SporadicCarbon Signatures in Early Type Ia Supernova Spectra

    SciTech Connect

    Thomas, R.C.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey,S.; Baltay, C.; Baron, E.; Bauer, A.; Buton, C.; Bongard, S.; Copin, Y.; Gangler, E.; Gilles, S.; Kessler, R.; Loken, S.; Nugent, P.; Pain, R.; Parrent, J.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigaudier, G.; Runge, K.; Scalzo, R.; Smadja, G.; Wang, L.; Weaver, B.A.

    2006-10-12

    We present four spectra of the Type Ia supernova SN Ia 2006Dextending from -7 to +13 days with respect to B-band maximum. The spectrainclude the strongest signature of unburned material at photosphericvelocities observed in a SN Ia to date. The earliest spectrum exhibits CII absorption features below 14,000 km/s, including a distinctive C IIlambda 6580 absorption feature. The carbon signatures dissipate as the SNapproaches peak brightness. In addition to discussing implications ofphotospheric-velocity carbon for white dwarf explosion models, we outlinesome factors that may influence the frequency of its detection before andaround peak brightness. Two effects are explored in this regard,including depopulation of the C II optical levels by non-LTE effects, andline-of-sight effects resulting from a clumpy distribution of unburnedmaterial with low volume-filling factor.

  6. Is There Evidence for a Hubble Bubble? The Nature of SN Ia Colors And Dust in External Galaxies

    SciTech Connect

    Conley, A.; Carlberg, R.G.; Guy, J.; Howell, D.A.; Jha, S.; Riess, A.G.; Sullivan, M.; /Toronto U., Astron. Dept.

    2007-06-06

    We examine recent evidence from the luminosity-redshift relation of Type Ia Supernovae for the {approx} 3 {sigma} detection of a ''Hubble bubble'' -- a departure of the local value of the Hubble constant from its globally averaged value. By comparing the MLCS2k2 fits used in that study to the results from other light-curve fitters applied to the same data, we demonstrate that this is related to the interpretation of SN color excesses (after correction for a light-curve shape-color relation) and the presence of a color gradient across the local sample. If the slope of the linear relation ({beta}) between SN color excess and luminosity is fit empirically, then the bubble disappears. If, on the other hand, the color excess arises purely from Milky-Way like dust, then SN data clearly favors a Hubble bubble. We demonstrate that SN data give {beta} {approx} 2, instead of the {beta} {approx} 4 one would expect from purely Milky-Way-like dust. This suggests that either SN intrinsic colors are more complicated than can be described with a single light-curve shape parameter, or that dust around SN is unusual. Disentangling these possibilities is both a challenge and an opportunity for large-survey SN Ia cosmology.

  7. A Swift Look at SN 2011fe: The Earliest Ultraviolet Observations of a Type Ia Supernova

    NASA Technical Reports Server (NTRS)

    Oates, Samantha; Holland, Stephen; Immler, Stefan; Brown, Peter J.; Dawson, Kyle S.; DePasquale, Massimiliano; Gronwall, Caryl; Kuin, Paul; Mazzali, Paolo; Miline, Peter; Siegel, Michael

    2012-01-01

    We present the earliest ultraviolet (UV) observations of the bright Type Ia supernova SN 2011fe/PTF11kly in the nearby galaxy M101 at a distance of only 6.4 Mpc. It was discovered shortly after explosion by the Palomar Transient Factory and first observed by Swift/UVOT about a day after explosion. The early UV light is well-defined, with approx. 20 data points per filter in the 5 days after explosion. With these early UV observations, we extend the near-UV template of SNe Ia to earlier times for comparison with observations at low and high redshift and report fits from semiempirical models of the explosion. We find the early UV count rates to be well fit by the superposition of two parabolic curves. Finally, we use the early UV flux measurements to examine a possible shock interaction with a non-degenerate companion. We find that even a solar mass companion at a distance of a few solar radii is unlikely at more than 95% confidence.

  8. ON THE NATURE OF THE PROGENITOR OF THE Type Ia SN2011fe IN M101

    SciTech Connect

    Liu Jifeng; Di Stefano, Rosanne; Wang Tao; Moe, Maxwell

    2012-04-20

    The explosion of a Type Ia supernova, SN2011fe, in the nearby Pinwheel galaxy (M101 at 6.4 Mpc) provides an opportunity to study pre-explosion images and search for the progenitor, which should consist of a white dwarf (WD), possibly surrounded by an accretion disk, in orbit with another star. We report on our use of deep Chandra observations and Hubble Space Telescope observations to limit the luminosity and temperature of the pre-explosion WD. It is found that if the spectrum was a blackbody, then pre-SN WDs with steady nuclear burning of the highest possible temperatures and luminosities are excluded assuming moderate n{sub H} values, but values of kT between roughly 10 eV and 60 eV are permitted even if the WD was emitting at the Eddington luminosity. This allows the progenitor to be an accreting nuclear-burning WD with an expanded photosphere 4-100 times the WD itself, or a super-critically accreting WD blowing off an optically thick strong wind, or possibly a recurrent nova with luminosities an order of magnitude lower than Eddington. The observations are also consistent with a double degenerate scenario, or a spinning down WD that has been spun up by accretion from the donor.

  9. Upper limits on the luminosity of the progenitor of Type Ia supernova SN 2014J

    NASA Astrophysics Data System (ADS)

    Nielsen, M. T. B.; Gilfanov, M.; Bogdán, Á.; Woods, T. E.; Nelemans, G.

    2014-08-01

    We analysed archival data of Chandra pre-explosion observations of the position of SN 2014J in M82. No X-ray source at this position was detected in the data, and we calculated upper limits on the luminosities of the progenitor. These upper limits allow us to firmly rule out an unobscured supersoft X-ray source progenitor with a photospheric radius comparable to the radius of white dwarf near the Chandrasekhar mass (˜1.38 M⊙) and mass accretion rate in the interval where stable nuclear burning can occur. However, due to a relatively large hydrogen column density implied by optical observations of the supernova, we cannot exclude a supersoft source with lower temperatures, kT ≲ 70 eV. We find that the supernova is located in the centre of a large structure of soft diffuse emission, about 200 pc across. The mass, ˜3 × 104 M⊙ and short cooling time of the gas, τcool ˜ 8 Myr, suggest that it is a supernova-inflated superbubble, associated with the region of recent star formation. If SN 2014J is indeed located inside the bubble, it likely belongs to the prompt population of Type Ia supernovae, with a delay time as short as ˜50 Myr. Finally, we analysed the one existing post-supernova Chandra observation and placed upper limit of ˜(1-2) × 1037 erg s-1 on the X-ray luminosity of the supernova itself.

  10. SPECTROSCOPIC OBSERVATIONS OF SN 2012fr: A LUMINOUS, NORMAL TYPE Ia SUPERNOVA WITH EARLY HIGH-VELOCITY FEATURES AND A LATE VELOCITY PLATEAU

    SciTech Connect

    Childress, M. J.; Scalzo, R. A.; Sim, S. A.; Tucker, B. E.; Yuan, F.; Schmidt, B. P.; Cenko, S. B.; Filippenko, A. V.; Silverman, J. M.; Contreras, C.; Hsiao, E. Y.; Phillips, M.; Morrell, N.; Jha, S. W.; McCully, C.; Anderson, J. P.; De Jaeger, T.; Forster, F.; Benetti, S.; Bufano, F.; and others

    2013-06-10

    We present 65 optical spectra of the Type Ia SN 2012fr, 33 of which were obtained before maximum light. At early times, SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II {lambda}6355 line that can be cleanly decoupled from the lower velocity ''photospheric'' component. This Si II {lambda}6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of {approx}12,000 km s{sup -1} until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v Almost-Equal-To 12,000 km s{sup -1} with narrow line width and long velocity plateau, as well as an HVF beginning at v Almost-Equal-To 31,000 km s{sup -1} two weeks before maximum. SN 2012fr resides on the border between the ''shallow silicon'' and ''core-normal'' subclasses in the Branch et al. classification scheme, and on the border between normal and high-velocity Type Ia supernovae (SNe Ia) in the Wang et al. system. Though it is a clear member of the ''low velocity gradient'' group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

  11. The End of Amnesia: Measuring the Metallicities of Type Ia SN Progenitors with Manganese Lines in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2009-05-01

    The Mn to Cr mass ratio in supernova ejecta has recently been proposed as a tracer of Type Ia SN progenitor metallicity. We review the advantages and problems of this observable quantity, and discuss them in the framework of the Tycho Supernova Remnant. The fluxes of the Mn and Cr Kα lines in the X-ray spectra of Tycho observed by the Suzaku satellite suggests a progenitors of supersolar metallicity.

  12. Early Radio and X-Ray Observations of the Youngest nearby Type Ia Supernova PTF 11kly (SN 2011fe)

    NASA Astrophysics Data System (ADS)

    Horesh, Assaf; Kulkarni, S. R.; Fox, Derek B.; Carpenter, John; Kasliwal, Mansi M.; Ofek, Eran O.; Quimby, Robert; Gal-Yam, Avishay; Cenko, S. Bradley; de Bruyn, A. G.; Kamble, Atish; Wijers, Ralph A. M. J.; van der Horst, Alexander J.; Kouveliotou, Chryssa; Podsiadlowski, Philipp; Sullivan, Mark; Maguire, Kate; Howell, D. Andrew; Nugent, Peter E.; Gehrels, Neil; Law, Nicholas M.; Poznanski, Dovi; Shara, Michael

    2012-02-01

    On 2011 August 24 (UT) the Palomar Transient Factory (PTF) discovered PTF11kly (SN 2011fe), the youngest and most nearby Type Ia supernova (SN Ia) in decades. We followed this event up in the radio (centimeter and millimeter bands) and X-ray bands, starting about a day after the estimated explosion time. We present our analysis of the radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate from the progenitor system of this supernova. We find a robust limit of \\dot{M}\\lesssim 10^{-8}(w/100\\,km\\,s^{-1})\\,M_{\\odot }\\,yr^{-1} from sensitive X-ray non-detections, as well as a similar limit from radio data, which depends, however, on assumptions about microphysical parameters. We discuss our results in the context of single-degenerate models for SNe Ia and find that our observations modestly disfavor symbiotic progenitor models involving a red giant donor, but cannot constrain systems accreting from main-sequence or sub-giant stars, including the popular supersoft channel. In view of the proximity of PTF11kly and the sensitivity of our prompt observations, we would have to wait for a long time (a decade or longer) in order to more meaningfully probe the circumstellar matter of SNe Ia.

  13. Early Radio and X-Ray Observations of the Youngest Nearby Type Ia Supernova PTF 11kly (SN 2011fe)

    NASA Technical Reports Server (NTRS)

    Horesh, Assaf; Kulkarni, S. R.; Fox, Derek B.; Carpenter, John; Kasliwal, Mansi M.; Ofek, Eran O.; Quimby, Robert; Gal-Yam, Avishay; Cenko, S. Bradley; deBruyn, A. G.; Kamble, Atish; Wijers, Ralph A. M. J.; vanderHorst, Alexander J.; Kouveliotou, Chryssa; Podsiadlowski, Philipp; Sullivan, Mark; Maguire, Kate; Howell, D. Andrew; Nugent, Peter E.; Gehrels, Neil; Law, Nicolas M.; Poznanski, Dovi; Shara, Michael

    2012-01-01

    On August 24 (UT) the Palomar Transient Factory (PTF) discovered PTF11kly (SN 2011fe), the youngest and most nearby type Ia supernova (SN Ia) in decades. We followed this event up in the radio (centimeter and millimeter bands) and X-ray bands, starting about a day after the estimated explosion time. We present our analysis of the radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate from the progenitor system of this supernova. We find a robust limit of M(raised dot) less than or equal to 10(exp -8) (w /100 kilometers per second ) solar mass yr(exp -1) from sensitive X-ray non-detections, as well as a similar limit from radio data, which depends, however, on assumptions about microphysical parameters. We discuss our results in the context of single-degenerate models for SNe Ia and find that our observations modestly disfavor symbiotic progenitor models involving a red giant donor, but cannot constrain systems accreting from main sequence or sub-giant stars, including the popular supersoft channel. In view of the proximity of PTF11kly and the sensitivity of our prompt observations we would have to wait for a long time (decade or longer) in order to more meaningfully probe the circumstellar matter of Ia supernovae.

  14. Early and late time VLT spectroscopy of SN 2001el - progenitor constraints for a type Ia supernova

    NASA Astrophysics Data System (ADS)

    Mattila, S.; Lundqvist, P.; Sollerman, J.; Kozma, C.; Baron, E.; Fransson, C.; Leibundgut, B.; Nomoto, K.

    2005-11-01

    We present early time high-resolution (VLT/UVES) and late time low-resolution (VLT/FORS) optical spectra of the normal type Ia supernova, SN 2001el. The high-resolution spectra were obtained 9 and 2 days before (B-band) maximum light. This was in order to allow the detection of narrow hydrogen and/or helium emission lines from the circumstellar medium of the supernova. No such lines were detected in our data. We therefore use these spectra together with photoionisation models to derive upper limits of 9×10-6 {M}_⊙ yr-1 and 5×10-5 {M}_⊙ yr-1 for the mass loss rate from the progenitor system of SN 2001el assuming velocities of 10 km s-1 and 50 km s-1, respectively, for a wind extending to outside at least a few × 1015 cm away from the supernova explosion site. So far, these are the best Hα based upper limits obtained for a type Ia supernova, and exclude a symbiotic star in the upper mass loss rate regime (so called Mira type stars) from being the progenitor of SN 2001el. The low-resolution spectrum was obtained in the nebular phase of the supernova, 400 days after the maximum light, to search for any hydrogen rich gas originating from the supernova progenitor system. However, we see no signs of Balmer lines in our spectrum. Therefore, we model the late time spectra to derive an upper limit of 0.03 M⊙ for solar abundance material present at velocities lower than 1000 km s-1 within the supernova explosion site. According to numerical simulations of Marietta et al. (2000) this is less than the expected mass lost by a subgiant, red giant or a main-sequence secondary star at a small binary separation as a result of the SN explosion. Our data therefore exclude these scenarios as the progenitor of SN 2001el. Finally, we discuss the origin of high velocity Ca II lines previously observed in a few type Ia supernovae before the maximum light. We see both the Ca II IR triplet and the H&K lines in our earliest (-9 days) spectrum at a very high velocity of up to 34 000

  15. Lensing Effects on the Brightness of SN Ia, When Using the Sinusoidal Potential.

    NASA Astrophysics Data System (ADS)

    Dadras, M. J.; Bartlett, D. F.; Motl, P.

    2004-05-01

    In this paper the effects of gravitational lensing of SN Ia are studied, for the case when the Newtonian potential is replaced by the sinusoidal potential (GM/r -> (GM cos[kr])/r). First we treat the point-mass case, then move on to the instance of a diffuse mass. As one might guess, with this new potential, the plot of the bending angle (α ) with respect to impact parameter (b) goes from dropping off as b-1, to having oscillations that die off as the b-1/2. This in turn will cause dramatic effects on magnification and brightness. In principle the value of the cosmological deceleration parameter (q0), can be determined by a measurement of the ratio of α to b. Wambsganss et al (1997) and Holz (1998) discussed the effects of weak gravitational lensing from large-scale structure on determining q0 within standard cosmology. Following their reasoning, we extend that work to the case of the sinusoidal potential.

  16. "New" B and V Photometry of the "Old" Type IA Supernova SN 1937C: Implications for HO

    NASA Astrophysics Data System (ADS)

    Pierce, Michael J.; Jacoby, George H.

    1995-12-01

    We have digitized and analyzed the original Baade and Zwicky 18 in. Palomar Schmidt films of the type Ia supernova SN 1937C. The data set consists of 76 films in the photographic bandpass mpg and a series of 50 previously unreduced photovisual (m_pv_) films. These data were supplemented by the three known, prediscovery plates of SN 1937C taken by Leutenegger and Grenat. The films and plates were scanned using the KPNO PDS microdensitometer and calibrated by fitting the integrated photographic density to a magnitude sequence of local standards on each film/plate. The resulting calibrations have typical rms dispersions of 0.06 and 0.04 mag for m_pg_ and m_pv_, respectively. Our magnitudes at the earliest epochs are systematically 0.30 mag fainter than those reported by Baade & Zwicky, with the two datasets converging by the eighth observation, about 11 days after maximum. We converted our mpg and mpv photometry to B and V using transformations determined both theoretically using synthetic photometry of spectrophotometric standards, and empirically using the local standard stars. The B and V light curves and B - V color evolution of SN 1937C were fitted with template light curves from previously well-observed supernovae to obtain B_max_= 8.94+/- 0.03, V_max_ = 9.00+/-0.03, and (B - V)_B(max)_ = -0.08 +/- 0.04. These correspond to M(B_max_)= - 19.42 and M( V_max_)= - 19.36 when combined with the Cepheid distance to IC 4182, the host galaxy. In comparing our results with the visual photometry of Beyer we found evidence for a color term which when applied to Beyer's data, leads to V_max_ = 8.87. We stress the importance of determining accurate color terms in the photometry of SN Ia due to the wide color range (from B - V ~ 0 to B - V ~1) through which they evolve over the first 30 days after maximum. The SN 1937C light curves were best fit by templates with very slow rates of decline. The correlation between decline rate and luminosity implies that SN 1937C, with {DELTA

  17. Cepheid Calibration of the Peak Brightness of SNe Ia.. 9; SN 1989B in NGC 3627

    NASA Technical Reports Server (NTRS)

    Saha, A.; Sandage, Allan; Tammann, G. A.; Labhardt, Lukas; Macchetto, F. D.; Panagia, N.

    1999-01-01

    Repeated imaging observations have been made of NGC 3627 with the Hubble Space Telescope in 1997/98, over an interval of 58 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F8141,V band. The galaxy hosted the prototypical, "Branch normal", type la supernova SN 1989B. A total of 83 variables have been found, of which 68 are definite Cepheid variables with periods ranging from 75 days to 3.85 days. The de-reddened distance modulus is determined to be (m - M)(sub 0) = 30.22 +/- 0.12 (internal uncertainty) using a subset of the Cepheid data whose reddening and error parameters are secure. The photometric data of Wells et al. (1994), combined with the Cepheid data for NGC 3627 give MB(max) = -19.36 +/- 0.18 and M(sub V)(max) = -19.34 +/- 0.16 for SN 1989B. Combined with the previous six calibrations in this program, plus two additional calibrations determined by others gives the mean absolute magnitudes at maximum of (M(sub B)) = -19.48 +/- 0.07 for "Brunch normal" SNe Ia at this interim stage in the calibration program. Using the argument by Wells et al. (1994) that SN 1989B here is virtually identical in decay rate and colors at maximum with SN 198ON in NGC 1316 in the Fornax cluster, and that such identity means nearly identical absolute magnitude, it follows that the difference in the distance modulus of NGC 3627 and NGC 1316 is 1.62 +/- 0.03 mag. Thus the NGC 3627 modulus implies that (m - M)(sub 0) = 31.84 for NGC 1316. The second parameter correlations of M(max) of blue SNe la with decay rate, color at maximum, and Hubble type are re-investigated. The dependence of (M(max)) on decay rate is non-linear, showing a minimum for decay rates between 1.0 less than ADelta(sub m)15 less than 1.6. Magnitudes corrected for decay rate show no dependence on Hubble type, but a dependence on color remains. Correcting both the fiducial sample of 34 SNe la with decay-rate data and the current eight calibrating SNe la for the correlation with

  18. X-Ray Observations of Type Ia Supernovae with Swift: Evidence of Circumstellar Interaction for SN 2005ke

    NASA Astrophysics Data System (ADS)

    Immler, S.; Brown, P. J.; Milne, P.; The, L.-S.; Petre, R.; Gehrels, N.; Burrows, D. N.; Nousek, J. A.; Williams, C. L.; Pian, E.; Mazzali, P. A.; Nomoto, K.; Chevalier, R. A.; Mangano, V.; Holland, S. T.; Roming, P. W. A.; Greiner, J.; Pooley, D.

    2006-09-01

    We present a study of the early (days to weeks) X-ray and UV properties of eight Type Ia supernovae (SNe Ia) that have been extensively observed with the X-Ray Telescope (XRT) and UV/Optical Telescope (UVOT) on board Swift, ranging from 5 to 132 days after the outburst. SN 2005ke is tentatively detected (at a 3-3.6 σ level of significance) in X-rays based on deep monitoring with the XRT ranging from 8 to 120 days after the outburst. The inferred X-ray luminosity [L0.3-2=(2+/-1)×1038 ergs s-1 0.3-2 keV band] is likely caused by interaction of the SN shock with circumstellar material (CSM) deposited by a stellar wind from the progenitor's companion star with a mass-loss rate of M˙~3×10-6 Msolar yr-1 (vw/10 km s-1). Evidence of CSM interaction in X-rays is independently confirmed by an excess of UV emission, as observed with the UVOT on board Swift, starting around 35 days after the explosion. The nondetection of SN 2005ke with Chandra 105 days after the outburst implies a rate of decline steeper than LX~t-0.75, consistent with the decline expected from the interaction of the SN shock with a spherically symmetric CSM (t-1). None of the other seven SNe Ia is detected in X-rays or shows a UV excess, which allows us to put tight constraints on the mass-loss rates of the progenitor systems.

  19. Constraints on kinematic model from recent cosmic observations: SN Ia, BAO and observational Hubble data

    SciTech Connect

    Xu, Lixin; Li, Wenbo; Lu, Jianbo E-mail: liwenbo10@yahoo.com.cn

    2009-07-01

    In this paper, linear first order expansion of deceleration parameter q(z) = q{sub 0}+q{sub 1}(1−a) (M{sub 1}), constant jerk j = j{sub 0} (M{sub 2}) and third order expansion of luminosity distance (M{sub 3}) are confronted with cosmic observations: SCP 307 SN Ia, BAO and observational Hubble data (OHD). Likelihood is implemented to find the best fit model parameters. All these models give the same prediction of the evolution of the universe which is undergoing accelerated expansion currently and experiences a transition from decelerated expansion to accelerated expansion. But, the transition redshift depends on the concrete parameterized form of the model assumed. M{sub 1} and M{sub 2} give value of transition redshift about z{sub t} ∼ 0.6. M{sub 3} gives a larger one, say z{sub t} ∼ 1. The χ{sup 2}/dof implies almost the same goodness of the models. But, for its badness of evolution of deceleration parameter at high redshift z > 1, M{sub 3} can not be reliable. M{sub 1} and M{sub 2} are compatible with ΛCDM model at the 2σ and 1σ confidence levels respectively. M{sub 3} is not compatible with ΛCDM model at 2σ confidence level. From M{sub 1} and M{sub 2} models, one can conclude that the cosmic data favor a cosmological model having j{sub 0} < −1.

  20. THE VERY EARLY LIGHT CURVE OF SN 2015F IN NGC 2442: A POSSIBLE DETECTION OF SHOCK-HEATED COOLING EMISSION AND CONSTRAINTS ON SN Ia PROGENITOR SYSTEM

    SciTech Connect

    Im, Myungshin; Choi, Changsu; Kim, Jae-Woo; Yoon, Sung-Chul; Ehgamberdiev, Shuhrat A.; Monard, Libert A. G.; Sung, Hyun-Il E-mail: changsu@astro.snu.ac.kr

    2015-11-15

    The main progenitor candidates of Type Ia supernovae (SNe Ia) are white dwarfs in binary systems where the companion star is another white dwarf (double degenerate (DD) system) or a less-evolved, non-degenerate star with R{sub *} ≳ 0.1 R{sub ⊙} (single degenerate system). However, no direct observational evidence exists to tell us which progenitor system is more common. Recent studies suggest that the light curve of a supernova shortly after its explosion can be used to set a limit on the progenitor size, R{sub *}. Here, we report high-cadence monitoring observations of SN 2015F, a normal SN Ia in the galaxy NGC 2442, starting about 84 days before the first light time. Using our daily cadence data, we capture the emergence of the radioactively powered light curve; more importantly, with >97.4% confidence, we detect possible dim precursor emission that appears roughly 1.5 days before the rise of the radioactively powered emission. The signal is consistent with theoretical expectations for a progenitor system involving a companion star with R{sub *} ≃ 0.1–1 R{sub ⊙} or a prompt explosion of a DD system, but is inconsistent with the typically invoked size of a white dwarf progenitor of R{sub *} ∼ 0.01 R{sub ⊙}. Upper limits on the precursor emission also constrain the progenitor size to be R{sub *} ≲ 0.1 R{sub ⊙} with a companion star size of R{sub *} ≲ 1.0 R{sub ⊙}, excluding a very large companion star in the progenitor system. Additionally, we find that the distance to SN 2015F is 23.9 ± 0.4 Mpc.

  1. Cepheid Calibration of the Peak Brightness of Type IA Supernovae. VI. SN 1960F in NGC 4496A

    NASA Astrophysics Data System (ADS)

    Saha, A.; Sandage, Allan; Labhardt, Lukas; Tammann, G. A.; Macchetto, F. D.; Panagia, N.

    1996-12-01

    Cepheid variables have been found in the SBcII galaxy NGC 4496A, parent to the Type Ia supernova 1960F. Of the 130 variables discovered with the Hubble Space Telescope (HST) over a 70 day observing internal from 1994 June to August, comprising 17 epochs in the F555W band and four epochs in the F814W band, 95 are bona fide Cepheids. The periods range from 7 days to greater than 70 days, with the mean magnitudes ranging from = 24.4 to 26.8. The distance modulus of NGC 4496A, based on the Cepheids, is (rn-Al)0 = 31.03±0.14, where a formal reddening of E(V-I) = 0.04±0.06 derived from the colors of the Cepheids has been used to account for possible extinction. There is no measurable differential reddening over the field. The absolute magnitudes of SN 1960F at maximum are M(B)max = -19.43±0.17 and M(V)max =-19.52±0.21. Combining these absolute magnitudes with the Hubble diagrams of "Branch normal" Type Ia supernovae (SNe Ia), determined earlier, gives Hubble constants, based on SN 1960F alone, of HO(B)=56±9 km s-1, (1) and H0(V) = 55±9 km s-1. (2) Combining the calibration of SN 1960F here with six other extant calibrations set out in Paper VII gives interim mean absolute magnitude calibrations of M(B) = -19.45±0.07 and 4M(V) max = -19.47±0.07, with no evidence for appreciable dependence on the light-curve decay rate. These mean interim calibrations require H0(B) = 57±4 km s-1 and H0(V) = 58±4 km s-1 Mpc-1.

  2. MID-IR SPECTRA OF TYPE Ia SN 2014J IN M82 SPANNING THE FIRST 4 MONTHS

    SciTech Connect

    Telesco, Charles M.; Li, Dan; Barnes, Peter J.; Mariñas, Naibí; Zhang, Han; Höflich, Peter; Álvarez, Carlos; Fernández, Sergio; Rebolo, Rafael; Hough, James H.; Levenson, N. A.; Pantin, Eric; Roche, Patrick E-mail: phoeflich77@gmail.com

    2015-01-10

    We present a time series of 8-13 μm spectra and photometry for SN 2014J obtained 57, 81, 108, and 137 days after the explosion using CanariCam on the Gran Telescopio Canarias. This is the first mid-IR time series ever obtained for a Type Ia supernova (SN Ia). These observations can be understood within the framework of the delayed detonation model and the production of ∼0.6 M {sub ☉} of {sup 56}Ni, consistent with the observed brightness, the brightness decline relation, and the γ-ray fluxes. The [Co III] line at 11.888 μm is particularly useful for evaluating the time evolution of the photosphere and measuring the amount of {sup 56}Ni and thus the mass of the ejecta. Late-time line profiles of SN 2014J are rather symmetric and not shifted in the rest frame. We see argon emission, which provides a unique probe of mixing in the transition layer between incomplete burning and nuclear statistical equilibrium. We may see [Fe III] and [Ni IV] emission, both of which are observed to be substantially stronger than indicated by our models. If the latter identification is correct, then we are likely observing stable Ni, which might imply central mixing. In addition, electron capture, also required for stable Ni, requires densities larger than ∼1 × 10{sup 9} g cm{sup –3}, which are expected to be present only in white dwarfs close to the Chandrasekhar limit. This study demonstrates that mid-IR studies of SNe Ia are feasible from the ground and provide unique information, but it also indicates the need for better atomic data.

  3. Nearby Supernova Factory Observations of SN 2005gj: Another TypeIa Supernova in a Massive Circumstellar Envelope

    SciTech Connect

    Aldering, G.; Antilogus, P.; Bailey, S.; Baltay, C.; Bauer, A.; Blanc, N.; Bongard, S.; Copin, Y.; Gangler, E.; Gilles, S.; Kessler, R.; Kocevski, D.; Lee, B.C.; Loken, S.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigaudier, G.; Scalzo, R.; Smadja, G.; Thomas, R.C.; Wang, L.; Weaver, B.A.; Rabinowitz, D.; Bauer, A.

    2006-06-01

    We report the independent discovery and follow-up observations of supernova 2005gj by the Nearby Supernova Factory. This is the second confirmed case of a ''hybrid'' Type Ia/IIn supernova, which like the prototype SN 2002ic, we interpret as the explosion of a white dwarf interacting with a circumstellar medium. Our early-phase photometry of SN 2005gj shows that the strength of the interaction between the supernova ejecta and circumstellar material is much stronger than for SN 2002ic. Our .rst spectrum shows a hot continuum with broad and narrow H{alpha} emission. Later spectra, spanning over 4 months from outburst, show clear Type Ia features combined with broad and narrow H{gamma}, H{beta},H{alpha} and He I {lambda}{lambda}5876,7065 in emission. At higher resolution, P Cygni profiles are apparent. Surprisingly, we also observe an inverted P Cygni profile for [O III] {lambda}5007. We find that the lightcurve and measured velocity of the unshocked circumstellar material imply mass loss as recently as 8 years ago. This is in contrast to SN 2002ic, for which an inner cavity in the circumstellar material was inferred. Within the context of the thin-shell approximation, the early lightcurve is well-described by a flat radial density profile for the circumstellar material. However, our decomposition of the spectra into Type Ia and shock emission components allows for little obscuration of the supernova, suggesting an aspherical or clumpy distribution for the circumstellar material. We suggest that the emission line velocity profiles arise from electron scattering rather than the kinematics of the shock. This is supported by the inferred high densities, and the lack of evidence for evolution in the line widths. Ground- and space-based photometry, and Keck spectroscopy, of the host galaxy are used to ascertain that the host galaxy has low metallicity (Z/Z{sub {circle_dot}} < 0.3; 95% confidence) and that this galaxy is undergoing a significant star formation event that

  4. Classification of PSN J05421980-2532399 as a pre-max Type Ia SN with WiFeS

    NASA Astrophysics Data System (ADS)

    Childress, M.; Scalzo, R.; Yuan, F.; Schmidt, B.; Tucker, B.

    2014-01-01

    We report spectroscopic classification of PSN J05421980-2532399 with the Wide Field Spectrograph (WiFeS - Dopita et al., 2007, ApSS, 310, 255) on the ANU 2.3m telescope at Siding Spring Observatory, NSW Australia, using the B3000/R3000 gratings (3500-9800 A, 1 A resolution). PSN J05421980-2532399 was discovered by Parker on 2014 Jan 17.52 at mag 17.0 in PGC 17633. An 80 minute spectrum of the SN on 2014 Jan 18.56 shows this object to be a type Ia supernova a few days before maximum light.

  5. Classification of PSN J06234727-6519484 as a post-max Type Ia SN with WiFeS

    NASA Astrophysics Data System (ADS)

    Childress, M.; Scalzo, R.; Yuan, F.; Schmidt, B.; Tucker, B.

    2013-11-01

    We report spectroscopic classification of PSN J06234727-6519484 with the Wide Field Spectrograph (WiFeS - Dopita et al., 2007, ApSS, 310, 255) on the ANU 2.3m telescope at Siding Spring Observatory, NSW Australia, using the B3000/R3000 gratings (3500-9800 A, 1 A resolution). PSN J06234727-6519484 was discovered by Parker on 2013 Nov 13.61 at mag 17.9 in PGC 75726. A 40 minute spectrum of the SN on 2013 Nov 14.70 shows this object to be a type Ia supernova about 10 days after maximum light.

  6. Spectral modelling of the 'super-Chandrasekhar' Type Ia SN 2009dc - testing a 2 M⊙ white dwarf explosion model and alternatives

    NASA Astrophysics Data System (ADS)

    Hachinger, Stephan; Mazzali, Paolo A.; Taubenberger, Stefan; Fink, Michael; Pakmor, Rüdiger; Hillebrandt, Wolfgang; Seitenzahl, Ivo R.

    2012-12-01

    Extremely luminous, 'super-Chandrasekhar' (SC) Type Ia Supernovae (SNe Ia) are as yet an unexplained phenomenon. We analyse a well-observed SN of this class, SN 2009dc, by modelling its photospheric spectra with a spectral synthesis code, using the technique of 'Abundance Tomography'. We present spectral models based on different density profiles, corresponding to different explosion scenarios, and discuss their consistency. First, we use a density structure of a simulated explosion of a 2 M⊙ rotating C-O white dwarf, which is often proposed as a possibility to explain SC SNe Ia. Then, we test a density profile empirically inferred from the evolution of line velocities (blueshifts). This model may be interpreted as a core-collapse SN with an ejecta mass of ˜3 M⊙. Finally, we calculate spectra assuming an 'interaction scenario'. In such a scenario, SN 2009dc would be a standard white dwarf (WD) explosion with a normal intrinsic luminosity, and this luminosity would be augmented by interaction of the ejecta with a H-/He-poor circumstellar medium. We find that none of the models tested easily explains SN 2009dc. With the 2 M⊙ WD model, our abundance analysis predicts small amounts of burning products in the intermediate-/high-velocity part of the ejecta (v ≳ 9000 km s-1). However, in the original explosion simulations, where the nuclear energy release per unit mass is large, burned material is present at high velocities. This contradiction can only be resolved if asymmetries strongly affect the radiative transfer or if C-O white dwarfs with masses significantly above 2 M⊙ exist. In a core-collapse scenario, low velocities of Fe-group elements are expected, but the abundance stratification in SN 2009dc seems 'SN-Ia-like'. The interaction-based model looks promising, and we have some speculations on possible progenitor configurations. However, radiation-hydrodynamics simulations will be needed to judge whether this scenario is realistic at all.

  7. Type Ia Supernova Properties as a Function of the Distance to the Host Galaxy in the SDSS-II SN Survey

    SciTech Connect

    Galbany, Lluis; et al.

    2012-08-20

    We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties (local star-formation rate, local metallicity, etc.). The sample consists of almost 200 spectroscopically or photometrically confirmed SNe Ia at redshifts below 0.25. The sample is split into two groups depending on the morphology of the host galaxy. We fit light-curves using both MLCS2k2 and SALT2, and determine color (AV, c) and light-curve shape (delta, x1) parameters for each SN Ia, as well as its residual in the Hubble diagram. We then correlate these parameters with both the physical and the normalized distances to the center of the host galaxy and look for trends in the mean values and scatters of these parameters with increasing distance. The most significant (at the 4-sigma level) finding is that the average fitted AV from MLCS2k2 and c from SALT2 decrease with the projected distance for SNe Ia in spiral galaxies. We also find indications that SNe in elliptical galaxies tend to have narrower light-curves if they explode at larger distances, although this may be due to selection effects in our sample. We do not find strong correlations between the residuals of the distance moduli with respect to the Hubble flow and the galactocentric distances, which indicates a limited correlation between SN magnitudes after standardization and local host metallicity.

  8. FLOYDS Classification of ASASSN-14em as a SN Ia Around Max

    NASA Astrophysics Data System (ADS)

    Arcavi, I.; Valenti, S.; Howell, D. A.; Hosseinzadeh, G.

    2014-07-01

    We obtained a spectrum of ASASSN-14em (ATel #6342) on 2014 July 26.3 (UT) with the robotic FLOYDS spectrograph mounted on the Faulkes Telescope North. Using Superfit (Howell et al. 2005, ApJ, 634, 1190) and SNID (Blondin & Tonry 2007, ApJ, 666, 1024), we find good matches to spectra of Type Ia supernovae near maximum light at the redshift of the host galaxy (z=0.03).

  9. No X-rays from the very nearby type Ia SN 2014J: Constraints on its environment

    SciTech Connect

    Margutti, R.; Parrent, J.; Kamble, A.; Soderberg, A. M.; Milisavljevic, D.; Drout, M. R.; Kirshner, R.; Foley, R. J.

    2014-07-20

    Deep X-ray observations of the post-explosion environment around the very nearby Type Ia SN 2014J (d{sub L} = 3.5 Mpc) reveal no X-ray emission down to a luminosity L{sub x} < 7 × 10{sup 36} erg s{sup –1} (0.3-10 keV) at δt ∼ 20 days after the explosion. We interpret this limit in the context of inverse Compton emission from upscattered optical photons by the supernova shock and constrain the pre-explosion mass-loss rate of the stellar progenitor system to be M-dot <10{sup −9} M{sub ⊙} yr{sup −1} (for wind velocity v{sub w} = 100 km s{sup –1}). Alternatively, the SN shock might be expanding into a uniform medium with density n{sub CSM} < 3 cm{sup –3}. These results rule out single-degenerate (SD) systems with steady mass loss until the terminal explosion and constrain the fraction of transferred material lost at the outer Lagrangian point to be ≤1%. The allowed progenitors are (1) white dwarf-white dwarf progenitors, (2) SD systems with unstable hydrogen burning experiencing recurrent nova eruptions with recurrence time t < 300 yr, and (3) stars where the mass loss ceases before the explosion.

  10. Confirmation of CSS160527:153151+372448 as Type Ia SN

    NASA Astrophysics Data System (ADS)

    Fatkhullin, T. A.; Moskvitin, A. S.; Komarova, V. N.

    2016-06-01

    We observed the field of SN candidate discovered by CRTS, CSS160527:153151+372448 (= ASASSN-16fc) with the 6-meter BTA telescope of SAO RAS equipped with the Scorpio-I focal reducer on the 2016 May, 31.934 (mid.

  11. Classification of SN 2016gmg (=PTSS-16opy), as a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Zhang, Jujia; Xin, Yuxin; Chang, Liang; Wang, Jianguo; Wang, Xiaofeng; Li, Wenxiong; Yang, Zesheng; Li, Bin; Xu, Zhijian; Zhao, Haibin; Wang, Lifan

    2016-09-01

    We obtained an optical spectrum (range 340-900 nm) of SN 2016gmg (=PTSS-16opy), discovered by the PMO-Tsinghua Supernova Survey (PTSS: http://119.78.210.3/ptss2/), on UT Sep. 29.55 2016 with the 2.4 m telescope (LJT + YFOSC) at LiJiang Observatory of Yunnan Observatories (YNAO).

  12. Spectroscopic Classification of SN 2016aqt as an Overluminous Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Rui, L.; Hosseinzadeh, G.; Yang, Y.; Arcavi, I.; Howell, D. A.; McCully, C.; Valenti, S.; Wang, X.; Huang, F.; Zhai, M.; Zhang, T.; Wang, L.

    2016-03-01

    We obtained two optical spectra of SN 2016aqt, discovered by R. Gagliano, J. Newton, R. Post, and T. Puckett (POSS), on 2016 March 2.7 UT with the Xinglong 2.16-m telescope (China) and on 2016 March 4.7 UT with the robotic FLOYDS instrument mounted on the LCOGT 2-meter telescope in Siding Spring (Australia).

  13. Spectroscopic Classification of SN 2016flv(= PTSS-16mvt) as a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Rui, Liming; Wang, Xiaofeng; Li, Wenxiong; Yang, Zesheng; Zhang, Ziyang; Xu, Zhijian; Li, Bin; Wang, Lifan; Zhao, Haibin; Xiao, Feng; Zhang, Tianmeng; Zhou, Fan; Zhang, Jujia; Han, Jietan

    2016-08-01

    We obtained an optical spectrum (range 390-840 nm) of SN 2016flv(= PTSS-16mvt), discovered by PMO-Tsinghua Supernova Survey (http://119.78.210.3/ptss2/), on UT Aug.28.6 2016 with the 2.16-m telescope (+BFOSC) at Xinglong Station of National Astronomical Observatories of China (NAOC).

  14. Spectroscopic Classification of SN 2016grz as a Young Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Zhang, Jujia; Xin, Yuxin; Wang, Xiaofeng; Li, Wenxiong; Yang, Zesheng; Xu, Zhijian; Tan, Hanjie; Zhang, Tianmeng

    2016-10-01

    We obtained an optical spectrum (range 310-810 nm) of SN 2016grz, discovered by the Tsinghua-NAOC Transient Survey, on UT Oct.01.9 2016 with the 2.4 m telescope (LJT + YFOSC) at LiJiang Observatory of Yunnan Observatories (YNAO).

  15. Du Pont Classification of ASASSN-16jc as a Young SN Ia

    NASA Astrophysics Data System (ADS)

    Shappee, Benjamin J.; Prieto, J. L.; Rich, J.; Seibert, M.; Madore, B.; Poetrodjojo, Henry; D'Agostino, Joshua

    2016-08-01

    We report optical spectroscopy (range 370-910 nm) of ASASSN-16jc discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014, ApJ, 788, 48) using the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory on Aug. 24 2016 UT. We performed a cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024).

  16. Spectroscopic Classification of SN 2016gvd as a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Zhang, Jujia; Zhang, Xiliang; Wang, Xiaofeng

    2016-10-01

    We obtained an optical spectrum (range 320-840 nm) of SN 2016gvd, discovered by Krisztián Sárneczky, Róbert Szakáts et al.(see ATel #9646), on UT Oct.23.7 2016 with the 2.4 m telescope (LJT + YFOSC) at LiJiang Observatory of Yunnan Observatories (YNAO).

  17. Spectral classification of ASASSN-16fo (AT 2016cob) as Type Ia SN

    NASA Astrophysics Data System (ADS)

    Piascik, A. S.; Steele, I. A.

    2016-05-01

    We conducted a spectroscopic observation of transient ASASSN-16fo (AT 2016cob) at 2016-05-29T23:40:07 UT. This transient was reported in ATel #9081 as observed by the All Sky Automated Survey for SuperNovae (ASAS-SN) on 2016-05-21.31 UT at position RA = 13:32:35.812, DEC = -05:16:21.33 A spectrum was obtained in the visible, 400-800nm, with resolution R~350, using the SPRAT spectrograph on the Liverpool Telescope located at Roque de los Muchachos, La Palma.

  18. SALT spectroscopic classification of LSQ16acz (= PS16bby = SN 2016bew) as a type-Ia supernova approaching maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of LSQ16acz (= PS16bby = SN 2016bew; Baltay et al. 2013, PASP, 125, 683) on 2016 Mar 14.9 UT, covering the wavelength range 340-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows LSQ16acz is a type-Ia supernova a few days before maximum light.

  19. THE FUNDAMENTAL METALLICITY RELATION REDUCES TYPE Ia SN HUBBLE RESIDUALS MORE THAN HOST MASS ALONE

    SciTech Connect

    Hayden, Brian T.; Garnavich, Peter M.; Gupta, Ravi R.; Sako, Masao; Mannucci, Filippo; Nichol, Robert C.

    2013-02-20

    Type Ia supernova Hubble residuals have been shown to correlate with host galaxy mass, imposing a major obstacle for their use in measuring dark energy properties. Here, we calibrate the fundamental metallicity relation (FMR) of Mannucci et al. for host mass and star formation rates measured from broadband colors alone. We apply the FMR to the large number of hosts from the SDSS-II sample of Gupta et al. and find that the scatter in the Hubble residuals is significantly reduced when compared with using only stellar mass (or the mass-metallicity relation) as a fit parameter. Our calibration of the FMR is restricted to only star-forming galaxies and in the Hubble residual calculation we include only hosts with log(SFR) > - 2. Our results strongly suggest that metallicity is the underlying source of the correlation between Hubble residuals and host galaxy mass. Since the FMR is nearly constant between z = 2 and the present, use of the FMR along with light-curve width and color should provide a robust distance measurement method that minimizes systematic errors.

  20. Non-LTE models for synthetic spectra of type Ia supernovae. III. An accelerated lambda-iteration procedure for the mutual interaction of strong spectral lines in SN Ia models with and without energy deposition

    NASA Astrophysics Data System (ADS)

    Pauldrach, A. W. A.; Hoffmann, T. L.; Hultzsch, P. J. N.

    2014-09-01

    Context. In type Ia supernova (SN Ia) envelopes a huge number of lines of different elements overlap within their thermal Doppler widths, and this problem is exacerbated by the circumstance that up to 20% of these lines can have a line optical depth higher than 1. The stagnation of the lambda iteration in such optically thick cases is one of the fundamental physical problems inherent in the iterative solution of the non-LTE problem, and the failure of a lambda iteration to converge is a point of crucial importance whose physical significance must be understood completely. Aims: We discuss a general problem related to radiative transfer under the physical conditions of supernova ejecta that involves a failure of the usual non-LTE iteration scheme to converge when multiple strong opacities belonging to different physical transitions come together, similar to the well-known situation where convergence is impaired even when only a single process attains high optical depths. The convergence problem is independent of the chosen frequency and depth grid spacing, independent of whether the radiative transfer is solved in the comoving or observer's frame, and independent of whether a common complete-linearization scheme or a conventional accelerated lambda iteration (ALI) is used. The problem appears when all millions of line transitions required for a realistic description of SN Ia envelopes are treated in the frame of a comprehensive non-LTE model. The only solution to this problem is a complete-linearization approach that considers all ions of all elements simultaneously, or an adequate generalization of the established ALI technique that accounts for the mutual interaction of the strong spectral lines of different elements and which thereby unfreezes the "stuck" state of the iteration. Methods: The physics of the atmospheres of SN Ia are strongly affected by the high-velocity expansion of the ejecta, which dominates the formation of the spectra at all wavelength ranges

  1. The conserved central domain of yeast U6 snRNA: importance of U2-U6 helix Ia in spliceosome assembly.

    PubMed Central

    Ryan, Daniel E; Abelson, John

    2002-01-01

    In the pre-mRNA processing machinery of eukaryotic cells, U6 snRNA is located at or near the active site for pre-mRNA splicing catalysis, and U6 is involved in catalyzing the first chemical step of splicing. We have further defined the roles of key features of yeast U6 snRNA in the splicing process. By assaying spliceosome assembly and splicing in yeast extracts, we found that mutations of yeast U6 nt 56 and 57 are similar to previously reported deletions of U2 nt 27 or 28, all within yeast U2-U6 helix Ia. These mutations lead to the accumulation of yeast A1 spliceosomes, which form just prior to the Prp2 ATPase step and the first chemical step of splicing. These results strongly suggest that, at a late stage of spliceosome assembly, the presence of U2-U6 helix Ia is important for promoting the first chemical step of splicing, presumably by bringing together the 5' splice site region of pre-mRNA, which is base paired to U6 snRNA, and the branchsite region of the intron, which is base paired to U2 snRNA, for activation of the first chemical step of splicing, as previously proposed by Madhani and Guthrie [Cell, 1992, 71: 803-817]. In the 3' intramolecular stem-loop of U6, mutation G81C causes an allele-specific accumulation of U6 snRNP. Base pairing of the U6 3' stem-loop in yeast spliceosomes does not extend as far as to include the U6 sequence of U2-U6 helix Ib, in contrast to the human U6 3' stem-loop structure. PMID:12212854

  2. KECK OBSERVATIONS OF THE YOUNG METAL-POOR HOST GALAXY OF THE SUPER-CHANDRASEKHAR-MASS TYPE Ia SUPERNOVA SN 2007if

    SciTech Connect

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Pain, R.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Chotard, N.; Copin, Y.; Gangler, E.

    2011-05-20

    We present Keck LRIS spectroscopy and g-band photometry of the metal-poor, low-luminosity host galaxy of the super-Chandrasekhar-mass Type Ia supernova SN 2007if. Deep imaging of the host reveals its apparent magnitude to be m{sub g} = 23.15 {+-} 0.06, which at the spectroscopically measured redshift of z{sub helio} = 0.07450 {+-} 0.00015 corresponds to an absolute magnitude of M{sub g} = -14.45 {+-} 0.06. Galaxy g - r color constrains the mass-to-light ratio, giving a host stellar mass estimate of log(M{sub *}/M{sub sun}) = 7.32 {+-} 0.17. Balmer absorption in the stellar continuum, along with the strength of the 4000 A break, constrains the age of the dominant starburst in the galaxy to be t{sub burst} = 123{sup +165}{sub -77} Myr, corresponding to a main-sequence turnoff mass of M/M{sub sun} = 4.6{sup +2.6}{sub -1.4}. Using the R{sub 23} method of calculating metallicity from the fluxes of strong emission lines, we determine the host oxygen abundance to be 12 + log(O/H){sub KK04} = 8.01 {+-} 0.09, significantly lower than any previously reported spectroscopically measured Type Ia supernova host galaxy metallicity. Our data show that SN 2007if is very likely to have originated from a young, metal-poor progenitor.

  3. Expectations for the Hard X-Ray Continuum and Gamma-Ray Line Fluxes from the Type Ia Supernova SN 2014J in M82

    NASA Astrophysics Data System (ADS)

    The, Lih-Sin; Burrows, Adam

    2014-05-01

    The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the 56Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior "X-ray" the bulk debris field in direct fashion, and do not depend on the ofttimes problematic and elaborate UV, optical, and near-infrared spectroscopy and radiative transfer that have informed the study of these events for decades. However, to date no hard photons have ever been detected from a Type Ia supernova in explosion. With the advent of the supernova SN 2014J in M82, at a distance of ~3.5 Mpc, this situation may soon change. Both NuSTAR and INTEGRAL have the potential to detect SN 2014J, and, if spectra and light curves can be measured, would usefully constrain the various explosion models published during the last ~30 yr. In support of these observational campaigns, we provide predictions for the hard X-ray continuum and gamma-line emissions for 15 Type Ia explosion models gleaned from the literature. The model set, containing as it does deflagration, delayed detonation, merger detonation, pulsational delayed detonation, and sub-Chandrasekhar helium detonation models, collectively spans a wide range of properties, and hence signatures. We provide a brief discussion of various diagnostics (with examples), but importantly make the spectral and line results available electronically to aid in the interpretation of the anticipated data.

  4. The dependence of the evolution of Type Ia SN progenitors on the C-burning rate uncertainty and parameters of convective boundary mixing

    NASA Astrophysics Data System (ADS)

    Chen, Michael C.; Herwig, Falk; Denissenkov, Pavel A.; Paxton, Bill

    2014-05-01

    Evolution of a Type Ia supernova (SN Ia) progenitor requires formation of a CO white dwarf (WD), which implies a dependence on the C-burning rate (CBR). It can also be affected by the recently identified possibility of C-flame quenching by convective boundary mixing. We present first results of our study of the combined effect of these two potential sources of uncertainty on the SN Ia progenitor evolution. We consider the possibility that the CBR is higher than its currently recommended value by as much as a factor of 1000 if unidentified resonances are important, or that it is significantly lower because of the hindrance effect. For stellar models that assume the Schwarzschild boundary for convection, the maximum initial mass for the formation of CO WDs increases from Mi ≈ 5.5 M⊙ for the CBR factor of 1000 to Mi ≳ 7.0 M⊙ for the CBR factor of 0.01. For C-flame quenching models, hybrid C-O-Ne WDs form for a range of initial mass of ΔMi ≈ 1 M⊙, which increases a fraction of stars that form WDs capable of igniting C in a thermonuclear runaway. The most extreme case is found for the CBR factor of 0.1 that is supported by the hindrance model. This nuclear physics assumption, combined with C-flame quenching, leads to the formation of a hybrid C-O-Ne WD with a mass of 1.3 M⊙. Such WDs do not need to accrete much mass to reach the Chandrasekhar limit.

  5. Expectations for the hard x-ray continuum and gamma-ray line fluxes from the typE IA supernova SN 2014J in M82

    SciTech Connect

    The, Lih-Sin; Burrows, Adam E-mail: burrows@astro.princeton.edu

    2014-05-10

    The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the {sup 56}Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior 'X-ray' the bulk debris field in direct fashion, and do not depend on the ofttimes problematic and elaborate UV, optical, and near-infrared spectroscopy and radiative transfer that have informed the study of these events for decades. However, to date no hard photons have ever been detected from a Type Ia supernova in explosion. With the advent of the supernova SN 2014J in M82, at a distance of ∼3.5 Mpc, this situation may soon change. Both NuSTAR and INTEGRAL have the potential to detect SN 2014J, and, if spectra and light curves can be measured, would usefully constrain the various explosion models published during the last ∼30 yr. In support of these observational campaigns, we provide predictions for the hard X-ray continuum and gamma-line emissions for 15 Type Ia explosion models gleaned from the literature. The model set, containing as it does deflagration, delayed detonation, merger detonation, pulsational delayed detonation, and sub-Chandrasekhar helium detonation models, collectively spans a wide range of properties, and hence signatures. We provide a brief discussion of various diagnostics (with examples), but importantly make the spectral and line results available electronically to aid in the interpretation of the anticipated data.

  6. Analysis of the flux and polarization spectra of the type Ia supernova SN 2001el: Exploring the geometry of the high-velocity Ejecta

    SciTech Connect

    Kasen, Daniel; Nugent, Peter; Wang, Lifan; Howell, D.A.; Wheeler, J. Craig; Hoeflich, Peter; Baade, Dietrich; Baron, E.; Hauschildt, P.H.

    2003-01-15

    SN 2001el is the first normal Type Ia supernova to show a strong, intrinsic polarization signal. In addition, during the epochs prior to maximum light, the CaII IR triplet absorption is seen distinctly and separately at both normal photospheric velocities and at very high velocities. The unusual, high-velocity triplet absorption is highly polarized, with a different polarization angle than the rest of the spectrum. The unique observation allows us to construct a relatively detailed picture of the layered geometrical structure of the supernova ejecta: in our interpretation, the ejecta layers near the photosphere (v approximately 10,000 km/s) obey a near axial symmetry, while a detached, high-velocity structure (v approximately 18,000-25,000 $ km/s) of CaII line opacity deviates from the photospheric axisymmetry. By partially obscuring the underlying photosphere, the high-velocity structure causes a more incomplete cancellation of the polarization of the photospheric light, and so gives rise to the polarization peak of the high-velocity IR triplet feature. In an effort to constrain the ejecta geometry, we develop a technique for calculating 3-D synthetic polarization spectra and use it to generate polarization profiles for several parameterized configurations. In particular, we examine the case where the inner ejecta layers are ellipsoidal and the outer, high-velocity structure is one of four possibilities: a spherical shell, an ellipsoidal shell, a clumped shell, or a toroid. The synthetic spectra rule out the clearly discriminated if observations are obtained from several different lines of sight. Thus, assuming the high velocity structure observed for SN 2001el is a consistent feature of at least known subset of type Ia supernovae, future observations and analyses such as these may allow one to put strong constraints on the ejecta geometry and hence on supernova progenitors and explosion mechanisms.

  7. Progenitors of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Maeda, Keiichi; Terada, Yukikatsu

    2016-07-01

    Natures of progenitors of type Ia Supernovae (SNe Ia) have not yet been clarified. There has been long and intensive discussion on whether the so-called single degenerate (SD) scenario or the double degenerate (DD) scenario, or anything else, could explain a major population of SNe Ia, but the conclusion has not yet been reached. With rapidly increasing observational data and new theoretical ideas, the field of studying the SN Ia progenitors has been quickly developing, and various new insights have been obtained in recent years. This paper aims at providing a summary of the current situation regarding the SN Ia progenitors, both in theory and observations. It seems difficult to explain the emerging diversity seen in observations of SNe Ia by a single population, and we emphasize that it is important to clarify links between different progenitor scenarios and different sub-classes of SNe Ia.

  8. SALT spectroscopic classification of PS16eho (= SN 2016gcr) as a type-Ia supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Dettman, K.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-09-01

    We obtained SALT (+RSS) spectroscopy of PS16eho (= SN 2016gcr) on 2016 Sep 12.0 UT, covering the wavelength range 350-930 nm. The spectrum is significantly contaminated with host galaxy light, and we confirm the redshift of the host galaxy 2MASX J22321713-2342106 z = 0.065 (Colless et al. 2003, 2dFGRS, arXiv:astroph/0306581; via NED) with numerous absorption and emission lines.

  9. Dark Matter Ignition of Type Ia Supernovae.

    PubMed

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way. PMID:26551803

  10. Dark Matter Ignition of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8 σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10 Myr old pulsars at the center of the Milky Way.

  11. Dark Matter Ignition of Type Ia Supernovae.

    PubMed

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way.

  12. A High-Resolution X-Ray and Optical Study of SN1006: Asymmetric Expansion and Small-Scale Structure in a Type Ia Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Winkler, P. Frank; Williams, Brian J.; Reynolds, Stephen P.; Petre, Robert; Long, Knox S.; Katsuda, Satoru; Hwang, Una

    2014-01-01

    We introduce a deep (670 ks) X-ray survey of the entire SN 1006 remnant from the Chandra X-Ray Observatory, together with a deep Ha image of SN 1006 from the 4 m Blanco telescope at CTIO. Comparison with Chandra images from 2003 gives the first measurement of the X-ray proper motions around the entire periphery, carried out over a 9 yr baseline. We find that the expansion velocity varies significantly with azimuth. The highest velocity of approx.7400 km/s (almost 2.5 times that in the northwest (NW)) is found along the southeast (SE) periphery, where both the kinematics and the spectra indicate that most of the X-ray emission stems from ejecta that have been decelerated little, if at all. Asymmetries in the distribution of ejecta are seen on a variety of spatial scales. Si-rich ejecta are especially prominent in the SE quadrant, while O and Mg are more uniformly distributed, indicating large-scale asymmetries arising from the explosion itself. Neon emission is strongest in a sharp filament just behind the primary shock along the NWrim, where the pre-shock density is highest. Here the Ne is likely interstellar, while Ne within the shell may include a contribution from ejecta. Within the interior of the projected shell we find a few isolated "bullets" of what appear to be supernova ejecta that are immediately preceded by bowshocks seen in Ha, features that we interpret as ejecta knots that have reached relatively dense regions of the surrounding interstellar medium, but that appear in the interior in projection. Recent three-dimensional hydrodynamic models for Type Ia supernovae display small-scale features that strongly resemble the ones seen in X-rays in SN 1006; an origin in the explosion itself or from subsequent hydrodynamic instabilities both remain viable options. We have expanded the search for precursor X-ray emission ahead of a synchrotron-dominated shock front, as expected from diffusive shock acceleration theory, to numerous regions along both the

  13. EVOLUTION OF POST-IMPACT COMPANION STARS IN SN Ia REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu

    2012-11-20

    The nature of the progenitor systems of Type Ia supernovae is still uncertain. One way to distinguish between the single-degenerate scenario and double-degenerate scenario is to search for the post-impact remnant star. To examine the characteristics of the post-impact remnant star, we have carried out three-dimensional hydrodynamic simulations of supernova impacts on main-sequence-like stars. We explore the evolution of the post-impact remnants using the stellar evolution code MESA. We find that the luminosity and radius of the remnant star dramatically increase just after the impact. After the explosion, post-impact companions continue to expand on a progenitor-dependent timescale of {approx}10{sup 2.5}-10{sup 3} years before contracting. It is found that the time evolution of the remnant star is dependent not only on the amount of energy absorbed but also on the depth of the energy deposition. We examine the viability of the candidate star Tycho G as the possible remnant companion in Tycho's supernova by comparing it to the evolved post-impact remnant stars in our simulations. The closest model in our simulations has a similar effective temperature, but the luminosity and radius are twice as large. By examining the angular momentum distribution in our simulations, we find that the surface rotational speed could drop to {approx}10 km s{sup -1} if the specific angular momentum is conserved during the post-impact evolution, implying that Tycho G cannot be completely ruled out because of its low surface rotation speed.

  14. Defining photometric peculiar type Ia supernovae

    SciTech Connect

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T.; Hsiao, E. Y.; Phillips, M. M.; Folatelli, G.; Anderson, J. P.

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  15. Sampling the probability distribution of Type Ia Supernova lightcurve parameters in cosmological analysis

    NASA Astrophysics Data System (ADS)

    Dai, Mi; Wang, Yun

    2016-06-01

    In order to obtain robust cosmological constraints from Type Ia supernova (SN Ia) data, we have applied Markov Chain Monte Carlo (MCMC) to SN Ia lightcurve fitting. We develop a method for sampling the resultant probability density distributions (pdf) of the SN Ia lightcuve parameters in the MCMC likelihood analysis to constrain cosmological parameters, and validate it using simulated data sets. Applying this method to the `joint lightcurve analysis (JLA)' data set of SNe Ia, we find that sampling the SN Ia lightcurve parameter pdf's leads to cosmological parameters closer to that of a flat Universe with a cosmological constant, compared to the usual practice of using only the best-fitting values of the SN Ia lightcurve parameters. Our method will be useful in the use of SN Ia data for precision cosmology.

  16. Type IA Supernovae

    NASA Technical Reports Server (NTRS)

    Wheeler, J. Craig

    1992-01-01

    Spectral calculations show that a model based on the thermonuclear explosion of a degenerate carbon/oxygen white dwarf provides excellent agreement with observations of Type Ia supernovae. Identification of suitable evolutionary progenitors remains a severe problem. General problems with estimation of supernova rates are outlined and the origin of Type Ia supernovae from double degenerate systems are discussed in the context of new rates of explosion per H band luminosity, the lack of observed candidates, and the likely presence of H in the vicinity of some SN Ia events. Re-examination of the problems of triggering Type Ia by accretion of hydrogen from a companion shows that there may be an avenue involving cataclysmic variables, especially if extreme hibernation occurs. Novae may channel accreting white dwarfs to a unique locus in accretion rate/mass space. Systems that undergo secular evolution to higher mass transfer rates could lead to just the conditions necessary for a Type Ia explosion. Tests involving fluorescence or absorption in a surrounding circumstellar medium and the detection of hydrogen stripped from a companion, which should appear at low velocity inside the white dwarf ejecta, are suggested. Possible observational confirmation of the former is described.

  17. Spectroscopy of SN 2016hnk (= ATLAS16dpc) with SOAR and SALT: A Peculiar Type-Ia Supernova Similar to PTF09dav

    NASA Astrophysics Data System (ADS)

    Pan, Y.-C.; Duarte, A. S.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.; Kniazev, A.

    2016-11-01

    We obtained spectroscopic observations of SN 2016hnk (= ATLAS16dpc) with the Goodman spectrograph on the Southern Astrophysical Research (SOAR) telescope on UT 2016 Oct 30.3 and with the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT) on UT 2016 Oct 31.0.

  18. What sodium absorption lines tell us about Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Soker, Noam

    2014-10-01

    We propose that the sodium responsible for the variable Na ID absorption lines in some Type Ia supernovae (SN Ia) originate mainly from dust residing at ˜1 pc from the supernovae. In this Na-from-dust absorption (NaDA) model, the process by which the SN Ia peak luminosity releases sodium from dust at ˜1 pc from the SN is similar to the processes by which solar radiation releases sodium from cometary dust when comets approach a distance of ≲ 1 au from the Sun. The dust grains are not sublimated but rather stay intact, and release sodium by photon-stimulated desorption (or photosputtering). Some of the Na might start in the gas phase before the explosion. Weakening in absorption strength is caused by Na-ionizing radiation of the SN. We apply the NaDA model to SN 2006X and SN 2007le, and find it to comply better with the observed time variability of the Na ID absorption lines than the Na recombination model. The mass in the dusty shell of the NaDA model is much too high to be accounted for in the single-degenerate scenario for SN Ia. Therefore, the presence of variable Na ID lines in some SN Ia further weakens the already very problematic single-degenerate scenario for SN Ia.

  19. Tests of Environmental Effects on Type Ia Supernova Production

    NASA Astrophysics Data System (ADS)

    Sadler, Suzanna M.; Strolger, L.; Wolff, S.

    2011-01-01

    The host galaxy environments of type Ia supernovae (SNe Ia) provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant event, and possibly the success in ultimately yielding a SN Ia. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search project. This study will uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star-formation, or metallicity. Here, we will show some preliminary results from SSP model fitting (of age and [Fe/H]) to a selection of hosts obtained thus far from this study. The complete sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the LOSS, SDSS, SNfactory and other surveys, and may ultimately steer future investigations towards more precise SN Ia cosmology.

  20. THE ROLE OF TYPE Ia SUPERNOVAE IN CHEMICAL EVOLUTION. I. LIFETIME OF TYPE Ia SUPERNOVAE AND METALLICITY EFFECT

    SciTech Connect

    Kobayashi, Chiaki; Nomoto, Ken'ichi E-mail: nomoto@astron.s.u-tokyo.ac.j

    2009-12-20

    We construct a new model of Type Ia Supernovae (SNe Ia), based on the single degenerate scenario, taking account of the metallicity dependences of white dwarf (WD) wind and the mass-stripping effect on the binary companion star. Our model naturally predicts that SN Ia lifetime distribution spans a range of 0.1-20 Gyr with the double peaks at approx0.1 and 1 Gyr. While the present SN Ia rate in elliptical galaxies can be reproduced with the old population of the red giants+WD systems, the large SN Ia rate in radio galaxies could be explained with the young population of the main-sequence+WD systems. Because of the metallicity effect, i.e., because of the lack of winds from WDs in the binary systems, the SN Ia rate in the systems with [Fe/H] approx<-1, e.g., high-z spiral galaxies, is supposed to be very small. Our SN Ia model can give better reproduction of the [(alpha, Mn, Zn)/Fe]-[Fe/H] relations in the solar neighborhood than other models such as the double-degenerate scenario. The metallicity effect is more strongly required in the presence of the young population of SNe Ia. We also succeed in reproducing the galactic supernova rates with their dependence on the morphological type of galaxies, and the cosmic SN Ia rate history with a peak at z approx 1. At z approx> 1, the predicted SN Ia rate decreases toward higher redshifts and SNe Ia will be observed only in the systems that have evolved with a short timescale of chemical enrichment. This suggests that the evolution effect in the supernova cosmology can be small.

  1. High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey. III. DA white dwarfs

    NASA Astrophysics Data System (ADS)

    Koester, D.; Voss, B.; Napiwotzki, R.; Christlieb, N.; Homeier, D.; Lisker, T.; Reimers, D.; Heber, U.

    2009-10-01

    Context: The ESO Supernova Ia Progenitor Survey (SPY) took high-resolution spectra of more than 1000 white dwarfs and pre-white dwarfs. About two thirds of the stars observed are hydrogen-dominated DA white dwarfs. Here we present a catalog and detailed spectroscopic analysis of the DA stars in the SPY. Aims: Atmospheric parameters effective temperature and surface gravity are determined for normal DAs. Double-degenerate binaries, DAs with magnetic fields or dM companions, are classified and discussed. Methods: The spectra are compared with theoretical model atmospheres using a χ2 fitting technique. Results: Our final sample contains 615 DAs, which show only hydrogen features in their spectra, although some are double-degenerate binaries. 187 are new detections or classifications. We also find 10 magnetic DAs (4 new) and 46 DA+dM pairs (10 new). Based on data obtained at the Paranal Observatory of the European Southern Observatory for programmes 165.H-0588 and 167.D-0407.

  2. Ultraviolet diversity of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A. V.; Fox, O. D.; Hillebrandt, W.; Kirshner, R. P.; Marion, G. H.; Milne, P. A.; Parrent, J. T.; Pignata, G.; Stritzinger, M. D.

    2016-09-01

    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 Å. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 Å (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.

  3. UV Emission in Type Ia Supernova Elliptical Host Galaxies

    NASA Astrophysics Data System (ADS)

    Tucker, Brad E.

    2015-03-01

    The current use of Type Ia supernova (SN Ia) as standard candles is to measure the dark energy equation-of-state to better than 10%. However, we still lack a clear understanding of their progenitor systems. We analyze the host galaxies of type Ia Supernova (SN Ia) discovered by the ESSENCE survey using UV and optical data, as studying the environments of SN Ia is a great way to understand the progenitors. We developed a new method for determining the SED and rest-frame magnitudes of the host galaxies and we use empirical relations to derive stellar mass and star-formation rate (SFR) measurements of the host galaxies. We find a high rate of UV emission in our passive galaxies, suggesting current star-formation in these galaxies.

  4. Asymmetric Explosion of Type Ia Supernovae and Their Observational Signatures

    SciTech Connect

    Maeda, Keiichi

    2010-06-01

    The nature of Type Ia supernova (SN Ia) explosions has not yet been clarified, despite their importance in astrophysics and cosmology. Recent theoretical investigations suggest that asymmetric distribution of initial thermonuclear sparks may be a key in the SN Ia explosion mechanism. In this paper, the first observational evidence of the asymmetry in SN Ia explosions is presented: We have found that late-time nebular spectra of various SNe Ia show a diversity in wavelengths of emission lines. This feature is inconsistent with any spherically symmetric explosion models, and indicates that the innermost region, a likely product of the deflagration wave propagation, shows an off-set with respect to the explosion center. The diversity in the emission-line wavelengths could naturally be explained by a combination of different viewing angles.

  5. THE LOCAL HOSTS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Neill, James D.; Martin, D. Christopher; Barlow, Tom A.; Foster, Karl; Friedman, Peter G.; Morrissey, Patrick; Wyder, Ted K.; Sullivan, Mark; Howell, D. Andrew; Conley, Alex; Seibert, Mark; Madore, Barry F.; Neff, Susan G.; Schiminovich, David; Bianchi, Luciana; Donas, Jose; Milliard, Bruno; Heckman, Timothy M.; Lee, Young-Wook; Rich, R. Michael

    2009-12-20

    We use multi-wavelength, matched aperture, integrated photometry from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). The ultraviolet (UV) imaging of local SN Ia hosts from GALEX allows a direct comparison with higher-redshift hosts measured at optical wavelengths that correspond to the rest-frame UV. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshold of approx10{sup 10} M{sub sun}, leading us to conclude that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia, and suggests that host age could be useful as a parameter in the fitting. Converting host mass to metallicity and computing {sup 56}Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the {sup 56}Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between {sup 56}Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. The details of the age-{sup 56}Ni mass correlations at low and higher redshift imply a luminosity

  6. Understanding the Progenitor Systems, Explosion Mechanisms, and Cosmological Utility of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan

    2014-10-01

    Despite using Type Ia supernovae (SN Ia) to precisely measure cosmological parameters, we still do not know basic facts about the progenitor systems and explosions. Theory suggests that SN Ia progenitor metallicity is correlated with its peak luminosity, but not its light-curve shape. As a result, this effect should lead to an increased Hubble scatter, reducing the precision with which we measure distances. If the average progenitor metallicity changes with redshift, cosmological measurements could be biased. Models also indicate that changing the progenitor metallicity will have little effect on the appearance of optical SN data, but significantly change UV spectra. These data can only be obtained with HST.We recently published the first detection of 2 SN Ia with different progenitor metallicities. These "twin" SN had nearly identical optical spectra and light-curve shapes, but different UV spectra and peak luminosities, consistent with the models. We now must increase the sample of SN Ia with UV spectral time series to investigate the impact of metallicity on SN properties. To do this, we plan to obtain UV spectral time series of 3 SN Ia, nearly doubling the sample. UV observations are critical to the understanding of SN Ia explosions and progenitors. This is our best opportunity to further our understanding of SN Ia while directly improving the utility of SN Ia for cosmology.Using parallel observations, we will obtain Cepheid distances to a subset of the SN for free, providing precise SN luminosities and a better measurement of the Hubble constant. The UV Initiative is an excellent opportunity for HST to address significant questions in SN physics and cosmology.

  7. THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

    SciTech Connect

    Brown, Peter J.

    2014-11-20

    We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10{sup 13} cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia.

  8. THE SPECTROSCOPIC DIVERSITY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Blondin, S.; Kirshner, R. P.; Mandel, K. S.; Challis, P.; Berlind, P.; Calkins, M.; Garnavich, P. M.; Jha, S. W.; Modjaz, M.; Riess, A. G.; Schmidt, B. P.

    2012-05-15

    We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5 m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. and Wang et al. The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic Si II {lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from {approx}0 to {approx}400 km s{sup -1} day{sup -1} considering the instantaneous velocity decline rate at maximum light. We find a weaker and less significant correlation between Si II velocity and intrinsic B - V color at maximum light than reported by Foley et al., owing to a more comprehensive treatment of uncertainties and host galaxy dust. We study the extent of nuclear burning and the presence of unburnt carbon in the outermost layers of the ejecta and report new detections of C II {lambda}6580 in 23 early-time SN Ia spectra. The frequency of C II detections is not higher in SNe Ia with bluer colors or narrower light curves, in conflict with the recent results of Thomas et al. Based on nebular spectra of 27 SNe Ia, we find no relation between the FWHM of the iron emission feature at {approx}4700 A and {Delta}m{sub 15}(B) after removing the two low-luminosity SN 1986G and SN 1991bg, suggesting that the

  9. HOST GALAXY PROPERTIES AND HUBBLE RESIDUALS OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    SciTech Connect

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon; Universite de Lyon 1, Villeurbanne; CNRS and others

    2013-06-20

    We examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory. We use host galaxy stellar masses and specific star formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-active galactic nucleus) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low- and high-mass hosts is 0.077 {+-} 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 {<=} log (M{sub *}/M{sub Sun }) {<=} 10.4). Although metallicity has been a favored interpretation for the origin of the Hubble residual trend with host mass, we illustrate how dust in star-forming galaxies and mean SN Ia progenitor age both evolve along the galaxy mass sequence, thereby presenting equally viable explanations for some or all of the observed SN Ia host bias.

  10. Quantitative comparison between type Ia supernova spectra at low and high redshifts: a case study

    NASA Astrophysics Data System (ADS)

    Garavini, G.; Folatelli, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Bronder, T.; Burns, M. S.; Conley, A.; Deustua, S. E.; Doi, M.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Kowalski, M.; Kuznetsova, N.; Lee, B. C.; Lidman, C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P. E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Thomas, R. C.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

    2007-08-01

    We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 ≤ z ≤ 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of the absorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z < 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.

  11. Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

    SciTech Connect

    Supernova Cosmology Project; Nugent, Peter E; Garavini, G.; Folatelli, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Bronder, J.; Burns, M.S.; Conley, A.; Deustua, S. E.; Doi, M.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Kowalski, M.; Kuznetsova, N.; Lee, B. C.; Lidman, C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P. E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Thomas, R. C.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

    2008-03-24

    We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z< 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.

  12. TYPE Ia SUPERNOVA CARBON FOOTPRINTS

    SciTech Connect

    Thomas, R. C.; Nugent, P.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Chotard, N.; Copin, Y.; Gangler, E.; and others

    2011-12-10

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II {lambda}6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s{sup -1}) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22{sup +10}{sub -6%} of SNe Ia exhibit spectroscopic C II signatures as late as -5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II {lambda}6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

  13. A Type Ia Supernova at Redshift 1.55 in Hubble Space Telescope Infrared Observations from CANDELS

    NASA Astrophysics Data System (ADS)

    Rodney, Steven A.; Riess, Adam G.; Dahlen, Tomas; Strolger, Louis-Gregory; Ferguson, Henry C.; Hjorth, Jens; Frederiksen, Teddy F.; Weiner, Benjamin J.; Mobasher, Bahram; Casertano, Stefano; Jones, David O.; Challis, Peter; Faber, S. M.; Filippenko, Alexei V.; Garnavich, Peter; Graur, Or; Grogin, Norman A.; Hayden, Brian; Jha, Saurabh W.; Kirshner, Robert P.; Kocevski, Dale; Koekemoer, Anton; McCully, Curtis; Patel, Brandon; Rajan, Abhijith; Scarlata, Claudia

    2012-02-01

    We report the discovery of a Type Ia supernova (SN Ia) at redshift z = 1.55 with the infrared detector of the Wide Field Camera 3 (WFC3-IR) on the Hubble Space Telescope (HST). This object was discovered in CANDELS imaging data of the Hubble Ultra Deep Field and followed as part of the CANDELS+CLASH Supernova project, comprising the SN search components from those two HST multi-cycle treasury programs. This is the highest redshift SN Ia with direct spectroscopic evidence for classification. It is also the first SN Ia at z > 1 found and followed in the infrared, providing a full light curve in rest-frame optical bands. The classification and redshift are securely defined from a combination of multi-band and multi-epoch photometry of the SN, ground-based spectroscopy of the host galaxy, and WFC3-IR grism spectroscopy of both the SN and host. This object is the first of a projected sample at z > 1.5 that will be discovered by the CANDELS and CLASH programs. The full CANDELS+CLASH SN Ia sample will enable unique tests for evolutionary effects that could arise due to differences in SN Ia progenitor systems as a function of redshift. This high-z sample will also allow measurement of the SN Ia rate out to z ≈ 2, providing a complementary constraint on SN Ia progenitor models.

  14. Type Ia supernova remnants: shaping by iron bullets

    NASA Astrophysics Data System (ADS)

    Tsebrenko, Danny; Soker, Noam

    2015-10-01

    Using 2D numerical hydrodynamical simulations of Type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g. SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed `ears', such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  15. On the relative frequencies of spectroscopically normal and peculiar type Ia supernovae

    NASA Technical Reports Server (NTRS)

    Branch, David; Fisher, Adam; Nugent, Peter

    1993-01-01

    After defining what we mean by spectroscopically 'normal' and 'peculiar' Type Ia supernove, we report the results of an attempt to subclassify 84 SNe Ia either as normal or as like one of the recent, peculiar SNe Ia: 1991T, 1991bg, or 1986G. Only SNe 1957A and 1960H are found to have been certifiably abnormal, with SN 1957A; appearing to have been like SN 1991bg, and SN 1960H having been like SN 1991bg or SN 1988G; SNe 1971I and 1980I are under suspicion of having been like SN 1986G, and SN 1988G of having been like SN 1991T. Of the SNe Ia we have been able to classify either as normal or as peculiar, 89% (or 83%, counting those under suspicion as peculiar) are normal. Our main conclusion is that the observational sample of SNe Ia is strongly peaked at 'spectroscopically normal.' We further conclude that when arranged in the photometric sequence of Phillips (1993) SNe Ia also form a spectroscopic sequence, and that peculiar SNe Ia are over-represented in the Phillips sample.

  16. Type Ia supernovae yielding distances with 3-4% precision

    SciTech Connect

    Kelly, Patrick L.; Filippenko, Alexei V.; Burke, David L.; Hicken, Malcolm; Ganeshalingam, Mohan; Zheng, Weikang

    2015-01-26

    The luminosities of Type Ia supernovae (SN), the thermonuclear explosions of white dwarf stars, vary systematically with their intrinsic color and light-curve decline rate. These relationships have been used to calibrate their luminosities to within ~0.14–0.20 mag from broadband optical light curves, yielding individual distances accurate to ~7–10%. Here we identify a subset of SN Ia that erupt in environments having high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, these SN can be calibrated to within ~0.065–0.075 mag, corresponding to ~3–4% in distance — the best yet with SN Ia by a substantial margin. The small scatter suggests that variations in only one or two progenitor properties account for their light-curve-width/color/luminosity relation.

  17. Luminosity distributions of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Ashall, C.; Mazzali, P.; Sasdelli, M.; Prentice, S. J.

    2016-08-01

    We have assembled a data set of 165 low redshift, z < 0.06, publicly available Type Ia supernovae (SNe Ia). We produce maximum light magnitude (MB and MV) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean MB and MV of SNe Ia are -18.58 ± 0.07 and -18.72 ± 0.05 mag, respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of MB and MV of SNe Ia are -19.10 ± 0.06 and -19.10 ± 0.05 mag, respectively. After correction for host galaxy extinction, `normal' SNe Ia (Δm15(B) < 1.6 mag) fill a larger parameter space in the width-luminosity relation than previously suggested, and there is evidence for luminous SNe Ia with large Δm15(B). We find a bimodal distribution in Δm15(B), with a pronounced lack of transitional events at Δm15(B) = 1.6 mag. We confirm that faster, low-luminosity SNe tend to come from passive galaxies. Dividing the sample by host galaxy type, SNe Ia from star-forming (S-F) galaxies have a mean MB = -19.20 ± 0.05 mag, while SNe Ia from passive galaxies have a mean MB = -18.57 ± 0.24 mag. Even excluding fast declining SNe, `normal' (MB < -18 mag) SNe Ia from S-F and passive galaxies are distinct. In the V band, there is a difference of 0.4 ± 0.13 mag between the median (MV) values of the `normal' SN Ia population from passive and S-F galaxies. This is consistent with (˜15 ± 10) per cent of `normal' SNe Ia from S-F galaxies coming from an old stellar population.

  18. Rates and progenitors of type Ia supernovae

    SciTech Connect

    Wood-Vasey, William Michael

    2004-01-01

    The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for

  19. Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

    SciTech Connect

    Graur, O.; Rodney, S. A.; Riess, A. G.; Medezinski, E.; Maoz, D.; Jha, S. W.; Holoien, T. W.-S.; McCully, C.; Patel, B.; Postman, M.; Dahlen, T.; Strolger, L.-G.; Coe, D.; Bradley, L.; Koekemoer, A.; Benítez, N.; Molino, A.; Jouvel, S.; Nonino, M.; Balestra, I.; and others

    2014-03-01

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ∼13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of −1.00{sub −0.06(0.10)}{sup +0.06(0.09)} (statistical){sub −0.08}{sup +0.12} (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.

  20. Type-Ia Supernova Rates to Redshift 2.4 from Clash: The Cluster Lensing and Supernova Survey with Hubble

    NASA Technical Reports Server (NTRS)

    Graur, O.; Rodney, S. A.; Maoz, D.; Riess, A. G.; Jha, S. W.; Postman, M.; Dahlen, T.; Holoien, T. W.-S.; McCully, C.; Patel, B.; Strolger, L.-G.; Benitez, N.; Coe, D.; Jouvel, S.; Medezinski, E.; Molino, A.; Nonino, M.; Bradley, L.; Koehemoer, A.; Balestra, I.; Cenko, S. B.; Clubb, K. I.; Dickinson, M. E.; Filippenko, A. V.; Frederiksen, T. F.; Garnavich, P.; Hjorth, J.; Jones, D. O.; Leibundgut, B.; Matheson, T.; Mobasher, B.; Rosati, P.; Silverman, J. M.; U., V.; Jedruszczuk, K.

    2014-01-01

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, approximately 13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z greater than 1.2.We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range z greater than 1.8 and less than 2.4. The results are consistent with the rates measured by the HST/ GOODS and Subaru Deep Field SN surveys.We model these results together with previous measurements at z less than 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of 1.00 (+0.06(0.09))/(-0.06(0.10)) (statistical) (+0.12/-0.08) (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at greater than 99% significance level.

  1. Evidence for Ni-56 yields Co-56 yields Fe-56 decay in type Ia supernovae

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J.; Kirshner, Robert P.; Pinto, Philip A.; Leibundgut, Bruno

    1994-01-01

    In the prevailing picture of Type Ia supernovae (SN Ia), their explosive burning produces Ni-56, and the radioactive decay chain Ni-56 yields Co-56 yields Fe-56 powers the subsequent emission. We test a central feature of this theory by measuring the relative strengths of a (Co III) emission feature near 5900 A and a (Fe III) emission feature near 4700 A. We measure 38 spectra from 13 SN Ia ranging from 48 to 310 days after maximum light. When we compare the observations with a simple multilevel calculation, we find that the observed Fe/Co flux ratio evolves as expected when the Fe-56/Co-56 abundance ratio follows from Ni-56 yields Co-56 yields Fe-56 decay. From this agreement, we conclude that the cobalt and iron atoms we observe through SN Ia emission lines are produced by the radioactive decay of Ni-56, just as predicted by a wide range of models for SN Ia explosions.

  2. Type Ia supernova rate studies from the SDSS-II Supernova Study

    SciTech Connect

    Dilday, Benjamin

    2008-08-01

    The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered ~ 500 spectroscopically confirmed SNe Ia with densely sampled (once every ~ 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents ~ 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SN Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.

  3. Gravitational Wave Emission from the Single-Degenerate Channel of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Falta, David; Fisher, Robert; Khanna, Gaurav

    2011-05-01

    The thermonuclear explosion of a C/O white dwarf as a Type Ia supernova (SN Ia) generates a kinetic energy comparable to that released by a massive star during a SN II event. Current observations and theoretical models have established that SNe Ia are asymmetric, and therefore—like SNe II—potential sources of gravitational wave (GW) radiation. We perform the first detailed calculations of the GW emission for a SN Ia of any type within the single-degenerate channel. The gravitationally confined detonation (GCD) mechanism predicts a strongly polarized GW burst in the frequency band around 1 Hz. Third-generation spaceborne GW observatories currently in planning may be able to detect this predicted signal from SNe Ia at distances up to 1 Mpc. If observable, GWs may offer a direct probe into the first few seconds of the SNe Ia detonation.

  4. THE IMPACT OF METALLICITY ON THE RATE OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Kistler, Matthew D.; Stanek, K. Z.; Kochanek, Christopher S.; Thompson, Todd A.; Prieto, Jose L.

    2013-06-20

    The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below {approx}8 M{sub Sun} leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z Almost-Equal-To 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

  5. The Impact of Metallicity on the Rate of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Kistler, Matthew D.; Stanek, K. Z.; Kochanek, Christopher S.; Prieto, José L.; Thompson, Todd A.

    2013-06-01

    The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below ~8 M ⊙ leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z ≈ 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

  6. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Héctor; Piro, Anthony L.; Schwab, Josiah; Badenes, Carles

    2016-07-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ˜103-104 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10-4. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

  7. Neutronization During Carbon Simmering In Type Ia Supernova Progenitors

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Héctor; Piro, Anthony L.; Schwab, Josiah; Badenes, Carles

    2016-07-01

    When a Type Ia supernova (SN Ia) progenitor first ignites carbon in its core, it undergoes ˜103–104 years of convective burning prior to the onset of thermonuclear runaway. This carbon simmering phase is important for setting the thermal profile and composition of the white dwarf. Using the MESA stellar evolution code, we follow this convective burning and examine the production of neutron-rich isotopes. The neutron content of the SN fuel has important consequences for the ensuing nucleosynthesis, and in particular, for the production of secondary Fe-peak nuclei like Mn and stable Ni. These elements have been observed in the X-ray spectra of SN remnants like Tycho, Kepler, and 3C 397, and their yields can provide valuable insights into the physics of SNe Ia and the properties of their progenitors. We find that weak reactions during simmering can at most generate a neutron excess of ≈ 3 × 10‑4. This is ≈ 70% lower than that found in previous studies that do not take the full density and temperature profile of the simmering region into account. Our results imply that the progenitor metallicity is the main contributor to the neutron excess in SN Ia fuel for Z ≳ 1/3 Z ⊙. Alternatively, at lower metallicities, this neutron excess provides a floor that should be present in any centrally-ignited SN Ia scenario.

  8. Rates and Properties of Type Ia Supernovae as a Function of Mass and Star Formation in Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Le Borgne, D.; Pritchet, C. J.; Hodsman, A.; Neill, J. D.; Howell, D. A.; Carlberg, R. G.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Lusset, V.; Perlmutter, S.; Ripoche, P.; Tao, C.

    2006-09-01

    We show that Type Ia supernovae (SNe Ia) are formed within both very young and old stellar populations, with observed rates that depend on the stellar mass and mean star formation rates (SFRs) of their host galaxies. Models in which the SN Ia rate depends solely on host galaxy stellar mass are ruled out with >99% confidence. Our analysis is based on 100 spectroscopically confirmed SNe Ia, plus 24 photometrically classified events, all from the Supernova Legacy Survey (SNLS) and distributed over 0.2SN Ia host galaxies by fitting their broadband spectral energy distributions with the galaxy spectral synthesis code PÉGASE.2. We show that the SN Ia rate per unit mass is proportional to the specific SFR of the parent galaxies-more vigorously star-forming galaxies host more SNe Ia per unit stellar mass, broadly equivalent to the trend of increasing SN Ia rate in later type galaxies seen in the local universe. Following earlier suggestions for a simple ``two-component'' model approximating the SN Ia rate, we find bivariate linear dependencies of the SN Ia rate on both the stellar masses and the mean SFRs of the host systems. We find that the SN Ia rate can be well represented as the sum of 5.3+/-1.1×10-14 SNe yr-1 Msolar-1 and 3.9+/-0.7×10-4 SNe yr-1 (Msolar yr-1)-1 of star formation. We also demonstrate a dependence of distant SN Ia light-curve shapes on star formation in the host galaxy, similar to trends observed locally. Passive galaxies, with no star formation, preferentially host faster declining/dimmer SNe Ia, while brighter events are found in systems with ongoing star formation.

  9. K-corrections and spectral templates of Type Ia supernovae

    SciTech Connect

    Nugent, Peter E; Hsiao, E.Y.; Conley, A.; Howell, D.A.; Sullivan, M.; Pritchet, C.J.; Carlberg, R.G.; Nugent, P.E.; Phillips, M.M.

    2007-03-20

    With the advent of large dedicated Type Ia supernova (SN Ia) surveys, K-corrections of SNe Ia and their uncertainties have become especially important in the determination of cosmological parameters. While K-corrections are largely driven by SN Ia broadband colors, it is shown here that the diversity in spectral features of SNe Ia can also be important. For an individual observation, the statistical errors from the inhomogeneity in spectral features range from 0.01 (where the observed and rest-frame filters are aligned) to 0.04 (where the observed and rest-frame filters are misaligned). To minimize the systematic errors caused by an assumed SN Ia spectral energy distribution (SED), we outline a prescription for deriving a mean spectral template time series that incorporates a large and heterogeneous sample of observed spectra. We then remove the effects of broadband colors and measure the remaining uncertainties in the K-corrections associated with the diversity in spectral features. Finally, we present a template spectroscopic sequence near maximum light for further improvement on the K-correction estimate. A library of ~;;600 observed spectra of ~;;100 SNe Ia from heterogeneous sources is used for the analysis.

  10. Cosmological Parameters from Type IA Supernova Multicolor Light Curve Shapes

    NASA Astrophysics Data System (ADS)

    Riess, A. G.; Press, W. H.; Kirshner, R. P.

    1995-12-01

    We present an empirical method that uses blue, visual, red, and infrared multicolor light curve shapes (MLCS) to estimate the luminosity, distance, and total line-of-sight absorption of Type Ia supernovae (SN Ia's). This method is first applied to a ``training set'' of eight SN Ia light curves with independent distance estimates to derive the correlation between the LCS and the luminosity. We employ a linear estimation algorithm of the type developed by Rybicki and Press. Some of the results are similar to those obtained by Hamuy et al. with the advantage that MLCS measures interstellar extinction and produces quantitative error estimates for the distance. The light curves for 20 SN Ia's (10 of which are from the CTIO/Calan Search) are used to determine the MLCS distances of these supernovae. The Hubble diagram constructed using these LCS distances has a remarkably small dispersion of sigma_ {B,V,R}=0.15 mag. We use the light curves of SN 1972E and SN 1981B and the Cepheid distance to NGC 5253 and NGC 4536 to derive 66 +/- 6 km s(-1) Mpc(-1) for the Hubble constant. We then measure the Local Group motion relative to these SN Ia's by analyzing the distribution on the sky of velocity residuals from a pure Hubble flow. The solution is consistent with the rest frame of the cosmic microwave background as determined by the COBE measurement of the dipole temperature anisotropy, and also with many plausible bulk flows expected to accompany observed density variations. It is inconsistent with the velocity observed by Lauer and Postman. We also find that the properties of dust in distant galaxies hosting SN Ia's are consistent with those of Galactic dust as measured by the interstellar extinction curve.

  11. DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES

    SciTech Connect

    Tsujimoto, Takuji; Shigeyama, Toshikazu

    2012-12-01

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

  12. THE FIRST MAXIMUM-LIGHT ULTRAVIOLET THROUGH NEAR-INFRARED SPECTRUM OF A TYPE Ia SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Marion, G. Howie; Challis, Peter; Kirshner, Robert P.; Berta, Zachory K.; Kromer, Markus; Taubenberger, Stefan; Hillebrandt, Wolfgang; Roepke, Friedrich K.; Ciaraldi-Schoolmann, Franco; Seitenzahl, Ivo R.; Pignata, Giuliano; Stritzinger, Maximilian D.; Filippenko, Alexei V.; Li Weidong; Silverman, Jeffrey M.; Folatelli, Gaston; Hsiao, Eric Y.; Morrell, Nidia I.; Simcoe, Robert A.; and others

    2012-07-01

    We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at UV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity to examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline ({Delta}m{sub 15}(B) = 1.69 {+-} 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.

  13. The cosmic gamma-ray background from Type Ia supernovae

    NASA Technical Reports Server (NTRS)

    The, Lih-Sin; Leising, Mark D.; Clayton, Donald D.

    1993-01-01

    We present an improved calculation of the cumulative gamma-ray spectrum of Type Ia supernovae during the history of the universe. We follow Clayton & Ward (1975) in using a few Friedmann models and two simple histories of the average galaxian nucleosynthesis rate, but we improve their calculation by modeling the gamma-ray scattering in detailed numerical models of SN Ia's. The results confirm that near 1 MeV the SN Ia background may dominate, and that it is potentially observable, with high scientific importance. A very accurate measurement of the cosmic background spectrum between 0.1 and 1.0 MeV may reveal the turn-on time and the evolution of the rate of Type Ia supernova nucleosynthesis in the universe.

  14. CIRCUMSTELLAR ABSORPTION IN DOUBLE DETONATION TYPE Ia SUPERNOVAE

    SciTech Connect

    Shen, Ken J.; Guillochon, James; Foley, Ryan J.

    2013-06-20

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  15. Type Ia Supernova Progenitors and Chemical Enrichment in Hydrodynamical Simulations. I. The Single-degenerate Scenario

    NASA Astrophysics Data System (ADS)

    Jiménez, Noelia; Tissera, Patricia B.; Matteucci, Francesca

    2015-09-01

    The nature of the Type Ia supernova (SN Ia) progenitors remains uncertain. This is a major issue for galaxy evolution models since both chemical and energetic feedback plays a major role in the gas dynamics, star formation, and therefore the overall stellar evolution. The progenitor models for the SNe Ia available in the literature propose different distributions for regulating the explosion times of these events. These functions are known as the delay time distributions (DTDs). This work is the first one in a series of papers aiming at studying five different DTDs for SNe Ia. Here we implement and analyze the single-degenerate (SD) scenario in galaxies dominated by a rapid quenching of the star formation, displaying the majority of the stars concentrated in the bulge component. We find a good fit to both the present observed SN Ia rates in spheroidal-dominated galaxies and the [O/Fe] ratios shown by the bulge of the Milky Way. Additionally, the SD scenario is found to reproduce a correlation between the specific SN Ia rate and the specific star formation rate (sSFR), which closely resembles the observational trend, at variance with previous works. Our results suggest that SN Ia observations in galaxies with very low and very high sSFRs can help to impose more stringent constraints on the DTDs and therefore on SN Ia progenitors.

  16. SNLS: Relating the properties of type Ia supernovae to the stellar populations of their host galaxies

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Pritchet, C. J.; Le Borgne, D.; Hodsman, A.; Howell, D. A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Filliol, M.; Perlmutter, S.; Tao, C.; SNLS Collaboration

    2005-12-01

    We examine the rates and properties of type Ia supernovae (SNe Ia) in relation to the physical parameters defining their host galaxy stellar populations. Using a sample of 114 spectroscopically confirmed SNe Ia discovered via the Supernova Legacy Survey (SNLS) distributed over 0.2SN Ia rate is proportional to the mass-normalised star-formation rate (SFR) of the parent galaxies - more vigorously star-forming galaxies have a higher SN Ia rate. Further, we identify a dependence of the SN rate on both the stellar mass and the current total SFRs of the host systems, suggesting SNe Ia can be generated from both very young and old stellar populations. We further demonstrate a dependence of SN light-curve shapes on the mean age of the stellar population from which the progenitor is drawn -- older systems preferentially host faster/dimmer SNe Ia, as observed in the local Universe. Though with current sample sizes, existing analysis techniques adequately account for these trends when using SNe Ia to constrain cosmological parameters, identifying and understanding the relationship between SNe Ia and their environments will lead to a future improved cosmological candle.

  17. Supernova 2010ev: A reddened high velocity gradient type Ia supernova

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Claudia P.; González-Gaitán, Santiago; Folatelli, Gastón; Pignata, Giuliano; Anderson, Joseph P.; Hamuy, Mario; Morrell, Nidia; Stritzinger, Maximilian; Taubenberger, Stefan; Bufano, Filomena; Olivares E., Felipe; Haislip, Joshua B.; Reichart, Daniel E.

    2016-05-01

    Aims: We present and study the spectroscopic and photometric evolution of the type Ia supernova (SN Ia) 2010ev. Methods: We obtain and analyze multiband optical light curves and optical/near-infrared spectroscopy at low and medium resolution spanning -7 days to +300 days from the B-band maximum. Results: A photometric analysis shows that SN 2010ev is a SN Ia of normal brightness with a light-curve shape of Δm15(B) = 1.12 ± 0.02 and a stretch s = 0.94 ± 0.01 suffering significant reddening. From photometric and spectroscopic analysis, we deduce a color excess of E(B - V) = 0.25 ± 0.05 and a reddening law of Rv = 1.54 ± 0.65. Spectroscopically, SN 2010ev belongs to the broad-line SN Ia group, showing stronger than average Si iiλ6355 absorption features. We also find that SN 2010ev is a high velocity gradient SN with v˙Si = 164 ± 7 km s-1 d-1. The photometric and spectral comparison with other supernovae shows that SN 2010ev has similar colors and velocities to SN 2002bo and SN 2002dj. The analysis of the nebular spectra indicates that the [Fe ii]λ7155 and [Ni ii]λ7378 lines are redshifted, as expected for a high velocity gradient supernova. All these common intrinsic and extrinsic properties of the high velocity gradient (HVG) group are different from the low velocity gradient (LVG) normal SN Ia population and suggest significant variety in SN Ia explosions. This paper includes data gathered with the Du Pont Telescope at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program GS-2010A-Q-14). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 085.D-0577).

  18. Do Single-Degenerate Type Ia Supernovae Generally Lead to Normal Type Ia Supernovae?

    NASA Astrophysics Data System (ADS)

    Fisher, Robert

    2016-01-01

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs (WDs) in the double-degenerate and the double-detonation channels, respectively, as the dominant progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly-accreting Chandrasekhar mass WDs in the single-degenerate channel remains more mysterious then ever. In this talk, I will clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia and demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass WDs in the single-degenerate channel are generally expected to be buoyancy-driven, and consequently lack a vigorous deflagration phase. I will show, using both analytic criteria and multidimensional numerical simulations, that the single-degenerate channel is inherently stochastic and leads to a variety of outcomes from failed SN 2002cx-like events through overluminous SN 1991T-like events. I will also demonstrate how the rates predicted from both the population of supersoft X-ray sources (SSSs) and binary population synthesis models of the single-degenerate channel can be brought into agreement with single-degenerate SNe Ia. I will further demonstrate that the single-degenerate channel contribution to the normal and failed 2002cx-like rates is not likely to exceed 1% of the total SNe Ia rate. I will conclude with a range of observational tests which will either support or strongly constrain the single-degenerate scenario.

  19. Type Ia supernova explosion models: Homogeneity versus diversity

    NASA Astrophysics Data System (ADS)

    Hillebrandt, Wolfgang; Niemeyer, Jens C.; Reinecke, Martin

    2000-06-01

    Type Ia supernovae (SN Ia) are generally believed to be the result of the thermonuclear disruption of Chandrasekhar-mass carbon-oxygen white dwarfs, mainly because such thermonuclear explosions can account for the right amount of 56Ni, which is needed to explain the light curves and the late-time spectra, and the abundances of intermediate-mass nuclei which dominate the spectra near maximum light. Because of their enormous brightness and apparent homogeneity SN Ia have become an important tool to measure cosmological parameters. In this article the present understanding of the physics of thermonuclear explosions is reviewed. In particular, we focus our attention on subsonic (``deflagration'') fronts, i.e. we investigate fronts propagating by heat diffusion and convection rather than by compression. Models based upon this mode of nuclear burning have been applied very successfully to the SN Ia problem, and are able to reproduce many of their observed features remarkably well. However, the models also indicate that SN Ia may differ considerably from each other, which is of importance if they are to be used as standard candles. .

  20. Instrument Requirements for Type Ia Supernova Gamma-Ray Studies

    NASA Astrophysics Data System (ADS)

    Leising, M.; Milne, P.; Lara, J.; The, L.

    2004-12-01

    Thermonuclear supernovae are widely used as distance indicators, which yields profound implications, yet details of their progenitor systems and explosion physics remain elusive. It has been argued for thirty-five years that these thoroughly radioactive objects can be understood through detailed gamma-ray line studies, but despite twenty years of gamma-ray instruments in orbit, no Type Ia supernova (SN Ia) has been detected in gamma-ray lines. Still the great promise of gamma-ray studies of SN Ia remains, but the instrument requirements, especially on line sensitivity, are substantial. Finally, a second-generation gamma-ray spectrometer, known now as the Advanced Compton Telescope, is being planned. Considering current SN Ia models of various types, including deflagrations, delayed detonations, and sub-Chandrasekhar-mass detonations, we outline the gamma-ray instrument requirements, especially line flux sensitivity and energy resolution, needed to discriminate among the possible models. We consider realistic SN Ia rates and distributions in space, plausible observing intervals and durations, and the information available from both gamma-ray photometry and spectroscopy. For example, we find that a wide-field compton telescope with energy resolution E/Δ E= 100 in a scanning mode would require broad line sensitivity of 7×10-7 cm-2 s-1 at 847 keV to distinguish deflagration models from delayed detonation models at the rate of one per year.

  1. SINGLE-DEGENERATE TYPE Ia SUPERNOVAE WITHOUT HYDROGEN CONTAMINATION

    SciTech Connect

    Justham, Stephen

    2011-04-01

    The lack of hydrogen in spectra of type Ia supernovae (SNe Ia) is often seen as troublesome for single-degenerate (SD) progenitor models. We argue that, since continued accretion of angular momentum can prevent explosion of the white dwarf, it may be natural for the donor stars in SD progenitors of SNe Ia to exhaust their envelopes and shrink rapidly before the explosion. This outcome seems most likely for SD SN Ia progenitors where mass transfer begins from a giant donor star and might extend to other SD systems. Not only is the amount of hydrogen left in such a system below the current detection limit, but the donor star is typically orders of magnitude smaller than its Roche lobe by the point when an SD SN Ia occurs, in which case attempts to observe collisions between SN shocks and giant donor stars seem unlikely to succeed. We consider the constraints on this model from the circumstellar structures seen in spectra of SN 2006X and suggest a novel explanation for the origin of this material.

  2. Observational Clues to the Progenitors of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Maoz, Dan; Mannucci, Filippo; Nelemans, Gijs

    2014-08-01

    Type Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and end points of stellar binary evolution. It has long been clear that a SN Ia must be the runaway thermonuclear explosion of a degenerate carbon-oxygen stellar core, most likely a white dwarf (WD). However, the specific progenitor systems of SNe Ia, and the processes that lead to their ignition, have not been identified. Two broad classes of progenitor binary systems have long been considered: single-degenerate (SD), in which a WD gains mass from a nondegenerate star; and double-degenerate (DD), involving the merger of two WDs. New theoretical work has enriched these possibilities with some interesting updates and variants. We review the significant recent observational progress in addressing the progenitor problem. We consider clues that have emerged from the observed properties of the various proposed progenitor populations, from studies of SN Ia sites—pre- and postexplosion—from analysis of the explosions themselves and from the measurement of event rates. The recent nearby and well-studied event, SN 2011fe, has been particularly revealing. The observational results are not yet conclusive and sometimes prone to competing theoretical interpretations. Nevertheless, it appears that DD progenitors, long considered the underdog option, could be behind some, if not all, SNe Ia. We point to some directions that may lead to future progress.

  3. High-Redshift Type Ia Supernova Rates in Galaxy Cluster and Field Environments

    NASA Astrophysics Data System (ADS)

    Barbary, Kyle Harris

    This thesis presents Type Ia supernova (SN Ia) rates from the Hubble Space Telescope (HST) Cluster Supernova Survey, a program designed to efficiently detect and observe high-redshift supernovae by targeting massive galaxy clusters at redshifts 0.9 < z < 1.46. Among other uses, measurements of the rate at which SNe Ia occur can be used to help constrain the SN Ia "progenitor scenario." The progenitor scenario, the process that leads to a SN~Ia, is a particularly poorly understood aspect of these events. Fortunately, the progenitor is directly linked to the delay time between star formation and supernova explosion. Supernova rates can be used to measure the distribution of these delay times and thus yield information about the elusive progenitors. Galaxy clusters, with their simpler star formation histories, offer an ideal environment for measuring the delay time distribution. In this thesis the SN Ia rate in clusters is calculated based on 8 +/- 1 cluster SNe Ia discovered in the HST Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. The SN Ia rate is found to be 0.50+0.23-0.19 (stat) +0.10-0.09 (sys) h 702 SNuB (SNuB = 10-12 SNe Lsun,B-1 yr-1), or in units of stellar mass, 0.36+0.16-0.13 (stat) +0.07-0.06 (sys) h 702 SNuM (SNuM = 10-12 SNe M sun-1 yr-1). This represents a factor of approximately 5 +/- 2 increase over measurements of the cluster rate at z < 0.2 and is the first significant detection of a changing cluster SN Ia rate with redshift. Parameterizing the late-time SN Ia delay time distribution with a power law in time with index s, this measurement in combination with lower-redshift cluster SN Ia rates constrains s = -1.41+0.47 -0.40, under the approximation of a single-burst cluster formation redshift of zf = 3. This is generally consistent with expectations for the "double degenerate" progenitor scenario and inconsistent with some models for the "single degenerate" progenitor scenario predicting a

  4. Type Ia supernovae: Pulsating delayed detonation models, IR light curves, and the formation of molecules

    NASA Technical Reports Server (NTRS)

    Hoflich, Peter; Khokhlov, A.; Wheeler, C.

    1995-01-01

    We computed optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SNe Ia). It is demonstrated that observations of the IR light curves can be used to identify subluminous SNe Ia by testing whether secondary maxima occur in the IR. Our pulsating delayed detonation models are in agreement with current observations both for subluminous and normal bright SN Ia, namely SN1991bg, SN1992bo, and SN1992bc. Observations of molecular bands provide a test to distinguish whether strongly subluminous supernovae are a consequence of the pulsating mechanism occurring in a high-mass white dwarf (WD) or, alternatively, are formed by the helium detonation in a low-mass WD as was suggested by Woosley. In the latter case, no carbon is left after the explosion of low-mass WDs whereas a log of C/O-rich material is present in pulsating delayed detonation models.

  5. Using Type IA supernova light curve shapes to measure the Hubble constant

    NASA Astrophysics Data System (ADS)

    Riess, Adam G.; Press, William H.; Kirshner, Robert P.

    1995-01-01

    We present an empirical method that uses visual band light curve shapes (LCSs) to estimate the luminosity of Type Ia supernova (SN Ia's). This method is first applied to a 'training set' of eight SN Ia light curves with independent distance estimates to derive the correlation between the LCS and the luminosity. We employ a linear estimation algorithm of the type developed by Rybicki and Press. The result is similar to that obtained by Hamuy et al. with the advantage that LCS produces quantitative error estimates for the distance. We then examine the light curves for 13 SN Ia's to determine the LCS distances of these supernovae. The Hubble diagram constructed using these LCS distances has a remarkably small dispersion of sigmaV = 0.21 mag. We use the light curve of SN 1972E and the Cepheid distance to NGC 5253 to derive 67 +/- 7 km/s/Mpc for the Hubble constant.

  6. Theoretical cosmic Type Ia supernova rates

    NASA Astrophysics Data System (ADS)

    Valiante, R.; Matteucci, F.; Recchi, S.; Calura, F.

    2009-10-01

    The purpose of this work is the computation of the cosmic Type Ia supernova rates, namely the frequency of Type Ia supernovae per unit time in a unitary volume of the Universe. Our main goal in this work is to predict the Type Ia supernova rates at very high redshifts and to check whether it is possible to select the best delay time distribution model, on the basis of the available observations of Type Ia supernovae. We compute the cosmic Type Ia supernova rates in different scenarios for galaxy formation and predict the expected number of explosions at high redshift ( z⩾2). Moreover, we adopt various progenitor models in order to compute the Type Ia supernova rate in typical elliptical galaxies of initial luminous masses of 1010M⊙,1011M⊙ and 1012M⊙, and compute the total amount of iron produced by Type Ia supernovae in each case. In this analysis we assume that Type Ia supernovae are caused by thermonuclear explosions of C-O white dwarfs in binary systems and we consider the most popular frameworks: the single degenerate and the double degenerate scenarios. The two competing schemes for the galaxy formation, namely the monolithic collapse and the hierarchical clustering, are also taken into account, by considering the histories of star formation increasing and decreasing with redshift, respectively. We calculate the Type Ia supernova rates through an analytical formulation which rests upon the definition of the SN Ia rate following an instantaneous burst of star formation as a function of the time elapsed from the birth of the progenitor system to its explosion as a Type Ia supernova (i.e. the delay time). What emerges from this work is that: (i) we confirm the result of previous papers that it is not easy to select the best delay time distribution scenario from the observational data and this is because the cosmic star formation rate dominates over the distribution function of the delay times; (ii) the monolithic collapse scenario for galaxy formation

  7. Type Ia supernovae as standard candles

    NASA Technical Reports Server (NTRS)

    Branch, David; Miller, Douglas L.

    1993-01-01

    The distribution of absolute blue magnitudes among Type Ia supernovae (SNs Ia) is studied. Supernovae were used with well determined apparent magnitudes at maximum light and parent galaxies with relative distances determined by the Tully-Fisher or Dn - sigma techniques. The mean absolute blue magnitude is given and the observational dispersion is only sigma(MB) 0.36, comparable to the expected combined errors in distance, apparent magnitude, and extinction. The mean (B-V) color at maximum light is 0.03 +/- 0.04, with a dispersion sigma(B-V) = 0.20. The Cepheid-based distance to IC 4182, the parent galaxy of the normal and unextinguished Type Ia SN 1937C, leads to a Hubble constant of H(0) + 51 +/- 12 km/s Mpc. The existence of a few SNs Ia that appear to have been reddened and dimmed by dust in their parent galaxies does not seriously compromise the use of SNs Ia as distance indicators.

  8. HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    SciTech Connect

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon; Universite de Lyon 1, Villeurbanne; CNRS and others

    2013-06-20

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and H{alpha}-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M{sub *}/M{sub Sun }) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

  9. Host Galaxies of Type Ia Supernovae from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Childress, M.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Hsiao, E. Y.; Kerschhaggl, M.; Kim, A. G.; Kowalski, M.; Loken, S.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.

    2013-06-01

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and Hα-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M */M ⊙) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

  10. Using the local gas-phase oxygen abundances to explore a metallicity dependence in SNe Ia luminosities

    NASA Astrophysics Data System (ADS)

    Moreno-Raya, M. E.; López-Sánchez, Á. R.; Mollá, M.; Galbany, L.; Vílchez, J. M.; Carnero, A.

    2016-10-01

    We present an analysis of the gas-phase oxygen abundances of a sample of 28 galaxies in the local Universe (z < 0.02) hosting Type Ia supernovae (SNe Ia). The data were obtained with the 4.2 m William Herschel Telescope. We derive local oxygen abundances for the regions where the SNe Ia exploded by calculating oxygen gradients through each galaxy (when possible) or assuming the oxygen abundance of the closest H II region. The sample selection only considered galaxies for which distances not based on the SN Ia method are available. Then, we use a principal component analysis to study the dependence of the absolute magnitudes on the colour of the SN Ia, the oxygen abundances of the region where they exploded and the stretch of the SN light curve. We demonstrate that our previous result suggesting a metallicity dependence on the SN Ia luminosity for non-reddened SNe Ia can be extended to our whole sample. These results reinforce the need of including a metallicity proxy, such as the oxygen abundance of the host galaxy, to minimize the systematic effect induced by the metallicity dependence of the SN Ia luminosity in future studies of SNe Ia at cosmological distances.

  11. THE DISCOVERY OF THE MOST DISTANT KNOWN TYPE Ia SUPERNOVA AT REDSHIFT 1.914

    SciTech Connect

    Jones, David O.; Rodney, Steven A.; Riess, Adam G.; Mobasher, Bahram; Dahlen, Tomas; Casertano, Stefano; Koekemoer, Anton; McCully, Curtis; Keeton, Charles R.; Patel, Brandon; Frederiksen, Teddy F.; Hjorth, Jens; Strolger, Louis-Gregory; Wiklind, Tommy G.; Challis, Peter; Hayden, Brian; Garnavich, Peter; Weiner, Benjamin J.; Filippenko, Alexei V.; and others

    2013-05-10

    We present the discovery of a Type Ia supernova (SN) at redshift z = 1.914 from the CANDELS multi-cycle treasury program on the Hubble Space Telescope (HST). This SN was discovered in the infrared using the Wide-Field Camera 3, and it is the highest-redshift Type Ia SN yet observed. We classify this object as a SN Ia by comparing its light curve and spectrum with those of a large sample of Type Ia and core-collapse SNe. Its apparent magnitude is consistent with that expected from the {Lambda}CDM concordance cosmology. We discuss the use of spectral evidence for classification of z > 1.5 SNe Ia using HST grism simulations, finding that spectral data alone can frequently rule out SNe II, but distinguishing between SNe Ia and SNe Ib/c can require prohibitively long exposures. In such cases, a quantitative analysis of the light curve may be necessary for classification. Our photometric and spectroscopic classification methods can aid the determination of SN rates and cosmological parameters from the full high-redshift CANDELS SN sample.

  12. THE RELATION BETWEEN EJECTA VELOCITY, INTRINSIC COLOR, AND HOST-GALAXY MASS FOR HIGH-REDSHIFT TYPE Ia SUPERNOVAE

    SciTech Connect

    Foley, Ryan J.

    2012-04-01

    Recently, using a large low-redshift sample of Type Ia supernovae (SNe Ia), we discovered a relation between SN Ia ejecta velocity and intrinsic color that improves the distance precision of SNe Ia and reduces potential systematic biases related to dust reddening. No SN Ia cosmological results have yet made a correction for the 'velocity-color' relation. To test the existence of such a relation and constrain its properties at high redshift, we examine a sample of 75 SNe Ia discovered and observed by the Sloan Digital Sky Survey-II Supernova Survey and Supernova Legacy Survey. From each spectrum, we measure ejecta velocities at maximum brightness for the Ca H and K and Si II {lambda}6355 features, v{sup 0}{sub CaHandK} and v{sup 0}{sub SiII}, respectively. Using SN light curve parameters, we determine the intrinsic B{sub max} - V{sub max} for each SN. Similar to what was found at low redshift, we find that SNe Ia with higher ejecta velocity tend to be intrinsically redder than SNe Ia with lower ejecta velocity. The distributions of ejecta velocities for SNe Ia at low and high redshift are similar, indicating that current cosmological results should have little bias related to the velocity-color relation. Additionally, we find a slight (2.4{sigma} significant) trend between SN Ia ejecta velocity and host-galaxy mass such that SNe Ia in high-mass host galaxies tend to have lower ejecta velocities as probed by v{sup 0}{sub CaHandK}. These results emphasize the importance of spectroscopy for SN Ia cosmology.

  13. Breaking the colour-reddening degeneracy in Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Sasdelli, Michele; Ishida, E. E. O.; Hillebrandt, W.; Ashall, C.; Mazzali, P. A.; Prentice, S. J.

    2016-07-01

    A new method to study the intrinsic colour and luminosity of Type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis on a spectral series for SNe Ia between -12.5 and +17.5 d from the B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of the colour excess due to dust extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic colour variability. Such a metric space is a good predictor of the epoch when the maximum in the B - V colour curve is reached. Multivariate partial least-squares regression predicts the intrinsic B-band light curve and the intrinsic B - V colour curve up to a month after the maximum. This allows us to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio RV in the host galaxy of SNe Ia is found, on average, to be consistent with typical Milky Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with a large sample publicly available. Future automated surveys, such as the Large Synoptic Survey Telescope, will provide a large number of light curves. The analysis shows that observing accompanying spectra for a significant number of SNe will be important even for normal SNe Ia.

  14. Constraining Type Ia Supernova Physics with Near-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sand, David; Valenti, Stefano; Howell, Andy; Graham, Melissa; Parrent, Jerod

    2014-08-01

    Despite their success as standardizable candles, relatively little is known about the exact progenitor(s) and explosion physics of type Ia supernovae -- a potential source of systematic uncertainty for future dark energy surveys, and a hole in our knowledge about stellar end-states. One promising route forward is the combination of dense optical time series and near-infrared (NIR) spectroscopic data sets. Recent work has suggested that the NIR can discern unburned carbon from the progenitor white dwarf more cleanly than in the optical, and its unique access to relatively unblended magnesium lines also probes the inner edge of carbon burning. Both measures provide a direct constraint for SN Ia explosion models, but only a handful of appropriate NIR spectroscopic time series exist. We propose to continue our campaign to roughly double the sample of SN Ia with such data (leveraging our access to a worldwide network of 1m imaging telescopes and twin robotic optical spectrographs) in order to begin to tackle our understanding of NIR spectral diagnostics and how they vary from supernova to supernova. During our 2014A time thus far, we have been intensely following the nearest SN Ia in a generation -- SN 2014J -- and have already submitted our initial results.

  15. Photometric Selection of High-Redshift Type Ia Supernova Candidates

    NASA Astrophysics Data System (ADS)

    Sullivan, M.; Howell, D. A.; Perrett, K.; Nugent, P. E.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Baumont, S.; Bronder, J.; Filiol, M.; Knop, R. A.; Perlmutter, S.; Tao, C.

    2006-02-01

    We present a method for selecting high-redshift Type Ia supernovae (SNe Ia) located via rolling SN searches. The technique, using both color and magnitude information of events from only two to three epochs of multiband real-time photometry, is able to discriminate between SNe Ia and core-collapse SNe. Furthermore, for SNe Ia the method accurately predicts the redshift, phase, and light-curve parameterization of these events based only on pre-maximum-light data. We demonstrate the effectiveness of the technique on a simulated survey of SNe Ia and core-collapse SNe, where the selection method effectively rejects most core-collapse SNe while retaining SNe Ia. We also apply the selection code to real-time data acquired as part of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). During the period 2004 May to 2005 January in the SNLS, 440 SN candidates were discovered, of which 70 were confirmed spectroscopically as SNe Ia and 15 as core-collapse events. For this test data set, the selection technique correctly identifies 100% of the identified SNe II as non-SNe Ia with only a 1%-2% false rejection rate. The predicted parameterization of the SNe Ia has a precision of Δz/(1+zspec)<0.09 in redshift and +/-2-3 rest-frame days in phase, providing invaluable information for planning spectroscopic follow-up observations. We also investigate any bias introduced by this selection method on the ability of surveys such as SNLS to measure cosmological parameters (e.g., w and ΩM) and find any effect to be negligible.

  16. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    SciTech Connect

    Lampeitl, Hubert; Smith, Mathew; Nichol, Robert C.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter M.; Goobar, Ariel; Im, Myungshin; /Seoul Natl. U. /Rutgers U., Piscataway

    2010-05-01

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3{sigma}) that SNe Ia are {approx_equal} 0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R{sub V} {approx_equal} 1, while SNe Ia in star-forming hosts require R{sub V} {approx} 2. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of > 4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

  17. A metric space for Type Ia supernova spectra

    NASA Astrophysics Data System (ADS)

    Sasdelli, Michele; Hillebrandt, W.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Benitez-Herrera, S.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Chen, J.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fink, M.; Fleury, M.; Fouchez, D.; Gangler, E.; Guy, J.; Ishida, E. E. O.; Kim, A. G.; Kowalski, M.; Kromer, M.; Lombardo, S.; Mazzali, P. A.; Nordin, J.; Pain, R.; Pécontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Suzuki, N.; Tao, C.; Taubenberger, S.; Thomas, R. C.; Tilquin, A.; Weaver, B. A.

    2015-02-01

    We develop a new framework for use in exploring Type Ia supernovae (SNe Ia) spectra. Combining principal component analysis (PCA) and partial least square (PLS) analysis we are able to establish correlations between the principal components (PCs) and spectroscopic/photometric SNe Ia features. The technique was applied to ˜120 SN and ˜800 spectra from the Nearby Supernova Factory. The ability of PCA to group together SNe Ia with similar spectral features, already explored in previous studies, is greatly enhanced by two important modifications: (1) the initial data matrix is built using derivatives of spectra over the wavelength, which increases the weight of weak lines and discards extinction, and (2) we extract time evolution information through the use of entire spectral sequences concatenated in each line of the input data matrix. These allow us to define a stable PC parameter space which can be used to characterize synthetic SN Ia spectra by means of real SN features. Using PLS, we demonstrate that the information from important previously known spectral indicators (namely the pseudo-equivalent width of Si II 5972 Å/Si II 6355 Å and the line velocity of S II 5640 Å/Si II 6355 Å) at a given epoch is contained within the PC space and can be determined through a linear combination of the most important PCs. We also show that the PC space encompasses photometric features like B/V magnitudes, B - V colours and SALT2 parameters c and x1. The observed colours and magnitudes, which are heavily affected by extinction, cannot be reconstructed using this technique alone. All the above-mentioned applications allowed us to construct a metric space for comparing synthetic SN Ia spectra with observations.

  18. THE EXCEPTIONALLY LUMINOUS TYPE Ia SUPERNOVA 2007if

    SciTech Connect

    Yuan, F.; Akerlof, C. W.; Miller, J. M.; McKay, T. A.; Quimby, R. M.; Kulkarni, S.; Wheeler, J. C.; Vinko, J.; Chatzopoulos, E.; Aharonian, F.

    2010-06-01

    SN 2007if was the third over-luminous Type Ia supernova (SN Ia) detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the SN and its host by ROTSE-III, HET, and Keck. From the H{sub {alpha}} line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the SN reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel ({approx}1.5 M {sub sun}) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 M {sub sun}. Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.

  19. CfAIR2: Near-infrared Light Curves of 94 Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Michael F.; Kirshner, Robert P.

    2015-09-01

    CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes {{JHK}}s photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z ˜ 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ˜13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

  20. PTF 11kx: a type Ia supernova with a symbiotic nova progenitor.

    PubMed

    Dilday, B; Howell, D A; Cenko, S B; Silverman, J M; Nugent, P E; Sullivan, M; Ben-Ami, S; Bildsten, L; Bolte, M; Endl, M; Filippenko, A V; Gnat, O; Horesh, A; Hsiao, E; Kasliwal, M M; Kirkman, D; Maguire, K; Marcy, G W; Moore, K; Pan, Y; Parrent, J T; Podsiadlowski, P; Quimby, R M; Sternberg, A; Suzuki, N; Tytler, D R; Xu, D; Bloom, J S; Gal-Yam, A; Hook, I M; Kulkarni, S R; Law, N M; Ofek, E O; Polishook, D; Poznanski, D

    2012-08-24

    There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumstellar material are detected, and the SN ejecta are seen to interact with circumstellar material starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi. PMID:22923575

  1. The Riddle of Steel: Fe-peak Elements in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles

    2016-06-01

    Recent results in have added to the controversy about the nature of the binary companion of the exploding white dwarf in Type Ia Supernovae, which must be either another white dwarf (double degenerate systems, DD) or a non-degenerate star (single degenerate systems, SD). On the one hand, there are no clear signs of dynamical interaction between SN ejecta and circumstellar material, which seems to favor DD systems. On the other hand, there is mounting evidence that at least some exploding SN Ia have ejecta masses very close to the Chandrasekhar limit, which is more naturally explained by the SD scenario. I will describe recent X-ray observations of Type Ia Supernova Remnants that can shed light on the properties of SN Ia progenitors and the SD vs. DD debate.

  2. PTF 11kx: a type Ia supernova with a symbiotic nova progenitor.

    PubMed

    Dilday, B; Howell, D A; Cenko, S B; Silverman, J M; Nugent, P E; Sullivan, M; Ben-Ami, S; Bildsten, L; Bolte, M; Endl, M; Filippenko, A V; Gnat, O; Horesh, A; Hsiao, E; Kasliwal, M M; Kirkman, D; Maguire, K; Marcy, G W; Moore, K; Pan, Y; Parrent, J T; Podsiadlowski, P; Quimby, R M; Sternberg, A; Suzuki, N; Tytler, D R; Xu, D; Bloom, J S; Gal-Yam, A; Hook, I M; Kulkarni, S R; Law, N M; Ofek, E O; Polishook, D; Poznanski, D

    2012-08-24

    There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumstellar material are detected, and the SN ejecta are seen to interact with circumstellar material starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi.

  3. Mapping the Kinematic Structure of Radioactive Ejecta in Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Gerardy, Christopher L.; Parrent, Jerod; Fesen, Robert A.; Hoflich, Peter

    2009-02-01

    Late-time (t ~ 300 d) observation of near-infrared (NIR) [Fe II] lines has proven to be a very powerful tool for probing the physics of Type Ia supernova (SN Ia) explosions. The few available examples have revealed that at least some SNe Ia exhibit a layered ejecta structure which persists down to the innermost regions of the SN envelope, in contradiction to all of the currently popular models of SNe Ia which predict that the innermost regions (at least) should exhibit large-scale turbulent mixing. Thus a key piece of physics is missing from our understanding of these events. NIR spectroscopy of Type Ia supernovae at these epochs tests the limits of 8 m class telescopes for even the brightest SNe Ia, and so these phenomena remain poorly observed. However, it may be possible to use the strong [Fe II] emission line at 7155 Ato similar effect. Unfortunately this line is usually partly blended with [Ca II] emission which complicates the extraction of the true [Fe II] line profile. We propose to use concurrent NIR and optical spectra of two recent nearby Type Ia supernovae, both to increase the still anemic data set of late- time SN Ia spectra, and to act as a pilot study to test whether the dramatic success obtained at great effort in the NIR can be reproduced much more cheaply through optical spectroscopy.

  4. Unified One-Dimensional Simulations of Gamma-Ray Line Emission from Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Milne, P. A.; Hungerford, A. L.; Fryer, C. L.; Evans, T. M.; Urbatsch, T. J.; Boggs, S. E.; Isern, J.; Bravo, E.; Hirschmann, A.; Kumagai, S.; Pinto, P. A.; The, L.-S.

    2004-10-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by gamma rays emitted by the decay of radioactive elements such as 56Ni and its decay products. These gamma rays are downscattered, absorbed, and eventually reprocessed into the optical emission that makes up the bulk of all SN observations. Detection of the gamma rays that escape the expanding star provide the only direct means to study this power source for SN Ia light curves. Unfortunately, disagreements between calculations for the gamma-ray lines have made it difficult to interpret any gamma-ray observations. Here we present a detailed comparison of the major gamma-ray line transport codes for a series of one-dimensional SN Ia models. Discrepancies in past results were due to errors in the codes, and the corrected versions of the seven different codes yield very similar results. This convergence of the simulation results allows us to infer more reliable information from the current set of gamma-ray observations of SNe Ia. The observations of SN 1986G, SN 1991T, and SN 1998bu are consistent with explosion models based on their classification: subluminous, superluminous, and normally luminous, respectively.

  5. An Optical and Near-Infrared Study of the Type Ia/IIn Supernova PS15si

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Charles D.; Andrews, Jennifer E.; Smith, Nathan; Milne, Peter; Rieke, George H.; Zheng, WeiKang; Filippenko, Alexei V.

    2016-08-01

    We present optical/near-infrared spectroscopy and photometry of the supernova (SN) PS15si. This object was originally identified as a Type IIn SN, but here we argue that it should be reclassified as a Type Ia SN with narrow hydrogen lines originating from interaction with circumstellar matter (CSM; i.e., SN Ia/IIn or SN Ia-CSM). Based on deep nondetections 27 days before discovery, we infer that this SN was discovered around or slightly before optical maximum, and we estimate the approximate time that it reached R-band maximum based on comparison with other SNe Ia/IIn. In terms of spectral morphology, we find that PS15si can be matched to a range of SN Ia spectral types, although SN 1991T-like SNe Ia provides the most self-consistent match. While this spectral classification agrees with analysis of most other SNe Ia/IIn, we find that the implied CSM-interaction luminosity is too low. We infer that the similarity between PS15si and the hot, overluminous, high-ionisation spectrum of SN 1991T is a consequence of a spectrum that originates in ejecta layers that are heated by ultraviolet/X-ray radiation from CSM interaction. In addition, PS15si may have rebrightened over a short timescale in the B and V bands around 85 days after discovery, perhaps indicating that the SN ejecta are interacting with a local enhancement in CSM produced by clumps or a shell at large radii.

  6. An optical and near-infrared study of the Type Ia/IIn Supernova PS15si

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Charles D.; Andrews, Jennifer E.; Smith, Nathan; Milne, Peter; Rieke, George H.; Zheng, WeiKang; Filippenko, Alexei V.

    2016-11-01

    We present optical/near-infrared spectroscopy and photometry of the supernova (SN) PS15si. This object was originally identified as a Type IIn SN, but here we argue that it should be reclassified as a Type Ia SN with narrow hydrogen lines originating from interaction with circumstellar matter (CSM; i.e. SN Ia/IIn or SN Ia-CSM). Based on deep non-detections 27 d before discovery, we infer that this SN was discovered around or slightly before optical maximum, and we estimate the approximate time that it reached R-band maximum based on comparison with other SNe Ia/IIn. In terms of spectral morphology, we find that PS15si can be matched to a range of SN Ia spectral types, although SN 1991T-like SNe Ia provides the most self-consistent match. While this spectral classification agrees with analysis of most other SNe Ia/IIn, we find that the implied CSM-interaction luminosity is too low. We infer that the similarity between PS15si and the hot, overluminous, high-ionization spectrum of SN 1991T is a consequence of a spectrum that originates in ejecta layers that are heated by ultraviolet/X-ray radiation from CSM interaction. In addition, PS15si may have rebrightened over a short time-scale in the B and V bands around 85 d after discovery, perhaps indicating that the SN ejecta are interacting with a local enhancement in CSM produced by clumps or a shell at large radii.

  7. Improved Distances to Type Ia Supernovae withMulticolor Light Curve Shapes: MLCS2k2

    SciTech Connect

    Jha, Saurabh; Riess, Adam G.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2007-01-05

    We present an updated version of the Multicolor Light Curve Shape method to measure distances to type Ia supernovae (SN Ia), incorporating new procedures for K-correction and extinction corrections. We also develop a simple model to disentangle intrinsic color variations and reddening by dust, and expand the method to incorporate U-band light curves and to more easily accommodate prior constraints on any of the model parameters. We apply this method to 133 nearby SN Ia, including 95 objects in the Hubble flow (cz {ge} 2500 km s{sup -1}), which give an intrinsic dispersion of less than 7% in distance. The Hubble flow sample, which is of critical importance to all cosmological uses of SN Ia, is the largest ever presented with homogeneous distances. We find the Hubble flow supernovae with H{sub 0}d{sub SN} {ge} 7400 km s{sup -1} yield an expansion rate that is 6.5 {+-} 1.8% lower than the rate determined from supernovae within that distance, and this can have a large effect on measurements of the dark energy equation of state with SN Ia. Peculiar velocities of SN Ia host galaxies in the rest frame of the Local Group are consistent with the dipole measured in the Cosmic Microwave Background. Direct fits of SN Ia that are significantly reddened by dust in their host galaxies suggest their mean extinction law may be described by R{sub V} {approx_equal} 2.7, but optical colors alone provide weak constraints on R{sub V}.

  8. IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?

    SciTech Connect

    Garcia-Senz, D.; Badenes, C.; Serichol, N. E-mail: carles@astro.tau.ac.il

    2012-01-20

    In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium. Our aim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the forward shock. We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity.

  9. THE HYBRID CONe WD + He STAR SCENARIO FOR THE PROGENITORS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Wang, B.; Meng, X.; Liu, D.-D.; Han, Z.; Liu, Z.-W.

    2014-10-20

    Hybrid CONe white dwarfs (WDs) have been suggested to be possible progenitors of type Ia supernovae (SNe Ia). In this Letter, we systematically studied the hybrid CONe WD + He star scenario for the progenitors of SNe Ia, in which a hybrid CONe WD increases its mass to the Chandrasekhar mass limit by accreting He-rich material from a non-degenerate He star. We obtained the SN Ia birthrates and delay times for this scenario using to a series of detailed binary population synthesis simulations. The SN Ia birthrates for this scenario are ∼0.033-0.539 × 10{sup –3} yr{sup –1}, which roughly accounts for 1%-18% of all SNe Ia. The estimated delay times are ∼28 Myr-178 Myr, which makes these the youngest SNe Ia predicted by any progenitor model so far. We suggest that SNe Ia from this scenario may provide an alternative explanation for type Iax SNe. We also presented some properties of the donors at the point when the WDs reach the Chandrasekhar mass. These properties may be a good starting point for investigating the surviving companions of SNe Ia and for constraining the progenitor scenario studied in this work.

  10. SN 1991T - Gamma-Ray Observatory's first supernova?

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Shankar, Anurag; Van Riper, Kenneth A.

    1991-01-01

    Consideration is given to the explosion of the Type Ia supernova SN 1991T in the nearby galaxy NGC 4527 detected in gamma-ray lines by the recently launched GRO. The dominant gamma-line and continuum features of the new 'delayed detonation' model FDEFA1 are calculated and compared to those for standard deflagration models W7 and cdtg7. It is shown that there are many useful hard photon discriminants of the Type Ia explosion mechanism that can, in principle, be detected by the OSSE and COMPTEL instruments on the GRO. Either SN 1991T, if bright enough, or one of the several Type Ia supernovae expected to be within the GRO's range during its active life, may make it possible to settle the detonation/deflagration debate, verify the generic thermonuclear white dwarf model of Type Ia explosions, and calibrate the Type Ia B(max)/847 keV line flux ratio.

  11. TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM

    SciTech Connect

    Silverman, Jeffrey M.; Nugent, Peter E.; Gal-Yam, Avishay; Arcavi, Iair; Ben-Ami, Sagi; Sullivan, Mark; Howell, D. Andrew; Graham, Melissa L.; Filippenko, Alexei V.; Bloom, Joshua S.; Cenko, S. Bradley; Clubb, Kelsey I.; Cao, Yi; Horesh, Assaf; Kulkarni, Shrinivas R.; Chornock, Ryan; Foley, Ryan J.; Coil, Alison L.; Griffith, Christopher V.; Kasliwal, Mansi M.; and others

    2013-07-01

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by H{alpha} emission (with widths of {approx}2000 km s{sup -1}) and exhibit large H{alpha}/H{beta} intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of H{alpha} 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag {<=} M{sub R} {<=} -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

  12. Type Ia supernovae: Progenitors and evolution with redshift

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Umeda, Hideyuki; Kobayashi, Chiaki; Hachisu, Izumi; Kato, Mariko; Tsujimoto, Takuji

    2000-06-01

    Relatively uniform light curves and spectral evolution of Type Ia supernovae(SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting WDs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction X(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependences of SNe Ia brightness on the galaxy types and the distance from the galactic center. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies. .

  13. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    NASA Technical Reports Server (NTRS)

    Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

    2013-01-01

    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.

  14. A Study of Carbon Features in Type Ia Supernova Spectra

    NASA Astrophysics Data System (ADS)

    Parrent, Jerod T.; Thomas, R. C.; Fesen, Robert A.; Marion, G. H.; Challis, Peter; Garnavich, Peter M.; Milisavljevic, Dan; Vinkò, Jòzsef; Wheeler, J. Craig

    2011-05-01

    One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features are not uncommon in the spectra of SNe Ia before maximum light, the presence of strong carbon absorption has been reported only in a minority of objects, typically during the pre-maximum phase. The reported low frequency of carbon detections may be due to low signal-to-noise data, low abundance of unburned material, line blending between C II λ6580 and Si II λ6355, ejecta temperature differences, asymmetrical distribution effects, or a combination of these. However, a survey of published pre-maximum spectra reveals that more SNe Ia than previously thought may exhibit C II λ6580 absorption features and relics of line blending near ~6300 Å. Here we present new SN Ia observations where spectroscopic signatures of C II λ6580 are detected and investigate the presence of C II λ6580 in the optical spectra of 19 SNe Ia using the parameterized spectrum synthesis code, SYNOW. Most of the objects in our sample that exhibit C II λ6580 absorption features are of the low-velocity gradient subtype. Our study indicates that the morphology of carbon-rich regions is consistent with either a spherical distribution or a hemispheric asymmetry, supporting the recent idea that SN Ia diversity may be a result of off-center ignition coupled with observer line-of-sight effects.

  15. A STUDY OF CARBON FEATURES IN TYPE Ia SUPERNOVA SPECTRA

    SciTech Connect

    Parrent, Jerod T.; Fesen, Robert A.; Milisavljevic, Dan; Thomas, R. C.; Marion, G. H.; Challis, Peter; Garnavich, Peter M.; Vinko, Jozsef; Wheeler, J. Craig

    2011-05-01

    One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features are not uncommon in the spectra of SNe Ia before maximum light, the presence of strong carbon absorption has been reported only in a minority of objects, typically during the pre-maximum phase. The reported low frequency of carbon detections may be due to low signal-to-noise data, low abundance of unburned material, line blending between C II {lambda}6580 and Si II {lambda}6355, ejecta temperature differences, asymmetrical distribution effects, or a combination of these. However, a survey of published pre-maximum spectra reveals that more SNe Ia than previously thought may exhibit C II {lambda}6580 absorption features and relics of line blending near {approx}6300 A. Here we present new SN Ia observations where spectroscopic signatures of C II {lambda}6580 are detected and investigate the presence of C II {lambda}6580 in the optical spectra of 19 SNe Ia using the parameterized spectrum synthesis code, SYNOW. Most of the objects in our sample that exhibit C II {lambda}6580 absorption features are of the low-velocity gradient subtype. Our study indicates that the morphology of carbon-rich regions is consistent with either a spherical distribution or a hemispheric asymmetry, supporting the recent idea that SN Ia diversity may be a result of off-center ignition coupled with observer line-of-sight effects.

  16. On the Dependence of Type Ia SNe Luminosities on the Metallicity of Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.; Galbany, Lluís; Vílchez, José Manuel; Carnero Rosell, Aurelio; Domínguez, Inmaculada

    2016-02-01

    The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence MB-Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.

  17. EARLY PHASE OBSERVATIONS OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc

    SciTech Connect

    Yamanaka, M.; Arai, A.; Chiyonobu, S.; Fukazawa, Y.; Ikejiri, Y.; Itoh, R.; Komatsu, T.; Miyamoto, H.; Kawabata, K. S.; Kinugasa, K.; Hashimoto, O.; Honda, S.; Tanaka, M.; Imada, A.; Kuroda, D.; Maeda, K.; Nomoto, K.; Kamata, Y.; Kawai, N.; Konishi, K.

    2009-12-20

    We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of the light curve is DELTAm{sub 15}(B) = 0.65 +- 0.03, which is one of the slowest among SNe Ia. The peak V-band absolute magnitude is estimated to be M{sub V} = -19.90 +- 0.15 mag if no host extinction is assumed. It reaches M{sub V} = -20.19 +- 0.19 mag if we assume the host extinction of A{sub V} = 0.29 mag. SN 2009dc belongs to the most luminous class of SNe Ia, like SNe 2003fg and 2006gz. Our JHK{sub s} -band photometry shows that this SN is also one of the most luminous SNe Ia in near-infrared wavelengths. We estimate the ejected {sup 56}Ni mass of 1.2 +- 0.3 M{sub sun} for the no host extinction case (and of 1.6 +- 0.4 M{sub sun} for the host extinction of A{sub V} = 0.29 mag). The C II lambda6580 absorption line remains visible until a week after the maximum brightness, in contrast to its early disappearance in SN 2006gz. The line velocity of Si II lambda6355 is about 8000 km s{sup -1} around the maximum, being considerably slower than that of SN 2006gz. The velocity of the C II line is similar to or slightly less than that of the Si II line around the maximum. The presence of the carbon line suggests that the thick unburned C+O layer remains after the explosion. Spectropolarimetric observations by Tanaka et al. indicate that the explosion is nearly spherical. These observational facts suggest that SN 2009dc is a super-Chandrasekhar mass SN Ia.

  18. THE VERY YOUNG TYPE Ia SUPERNOVA 2013dy: DISCOVERY, AND STRONG CARBON ABSORPTION IN EARLY-TIME SPECTRA

    SciTech Connect

    Zheng, WeiKang; Filippenko, Alexei V.; Nugent, Peter E.; Graham, Melissa; Kelly, Patrick L.; Fox, Ori D.; Shivvers, Isaac; Clubb, Kelsey I.; Li, Weidong; Silverman, Jeffrey M.; Howie Marion, G.; Kasen, Daniel; Wang, Xiaofeng; Valenti, Stefano; Howell, D. Andrew; Ciabattari, Fabrizio; Cenko, S. Bradley; Balam, Dave; Hsiao, Eric; Sand, David; and others

    2013-11-20

    The Type Ia supernova (SN Ia) 2013dy in NGC 7250 (d ≈ 13.7 Mpc) was discovered by the Lick Observatory Supernova Search. Combined with a prediscovery detection by the Italian Supernova Search Project, we are able to constrain the first-light time of SN 2013dy to be only 0.10 ± 0.05 days (2.4 ± 1.2 hr) before the first detection. This makes SN 2013dy the earliest known detection of an SN Ia. We infer an upper limit on the radius of the progenitor star of R {sub 0} ≲ 0.25 R {sub ☉}, consistent with that of a white dwarf. The light curve exhibits a broken power law with exponents of 0.88 and then 1.80. A spectrum taken 1.63 days after first light reveals a C II absorption line comparable in strength to Si II. This is the strongest C II feature ever detected in a normal SN Ia, suggesting that the progenitor star had significant unburned material. The C II line in SN 2013dy weakens rapidly and is undetected in a spectrum 7 days later, indicating that C II is detectable for only a very short time in some SNe Ia. SN 2013dy reached a B-band maximum of M{sub B} = –18.72 ± 0.03 mag ∼17.7 days after first light.

  19. Constraining Cosmic Evolution of Type Ia Supernovae

    SciTech Connect

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  20. Type Ia Supernova Rate Measurements to Redshift 2.5 from Candles: Searching for Prompt Explosions in the Early Universe

    NASA Technical Reports Server (NTRS)

    Rodney, Steven A.; Riess, Adam G.; Strogler, Louis-Gregory; Dahlen, Tomas; Graur, Or; Casertano, Stefano; Dickinson, Mark E.; Ferguson, Henry C.; Garnavich, Peter; Cenko, Stephen Bradley

    2014-01-01

    The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope(HST) that surveyed a total area of approx. 0.25 deg(sup 2) with approx.900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z approx. 2.5. We classify approx. 24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only approx. 3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction isfP0.530.09stat0.100.10sys0.26, consistent with a delay time distribution that follows a simplet1power law for all timest40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20 of all SN Ia explosions though further analysis and larger samples will be needed to examine that suggestion.

  1. VELOCITY EVOLUTION AND THE INTRINSIC COLOR OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Foley, Ryan J.; Sanders, Nathan E.; Kirshner, Robert P.

    2011-12-01

    To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of Si II {lambda}6355 and Ca II H and K are related to the B - V color at peak brightness. We find that the maximum-light velocity of Si II {lambda}6355 and Ca II H and K and the maximum-light pseudo-equivalent width of Si II {lambda}6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the Si II {lambda}6355 measurements. Ca II H and K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia-even after removing a linear trend with velocity-indicating that lower-velocity SNe Ia are more 'standard crayons'. Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.

  2. SNLS: The Supernova Type Ia Rate at z = 0.47

    NASA Astrophysics Data System (ADS)

    Neill, J. D.; Sullivan, M.; Balam, D.; Astier, P.; Aubourg, E.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Howell, D. A.; Lafoux, H.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, J.; Graham, M.; Hsiao, E.; Lusset, V.; Ripoche, P.; Mourao, A.; Perlmutter, S.; Tao, C.

    2005-12-01

    We present a preliminary measurement of the distant Type Ia supernova rate derived from the Canada -- France -- Hawaii Telescope Supernova Legacy Survey (SNLS). By observing four one-square degree fields with a high temporal frequency (< Δ t > ˜ 4 observer-frame days) over large fractions of a year ( ˜ 6 months each field, with breaks during full moon) and using 8 meter-class telescopes for spectroscopic followup, the survey not only provides the dense time sampling needed to achieve a high completeness, but also enjoys the benefit of high quality spectroscopy to verify the Type Ia candidates and hence reduce contamination from non-Type Ia events. The goal of the survey is to measure ˜ 700 Type Ia SNe out to z ˜ 1 over a period of 5 years. We use the first two years of survey data to begin characterizing the Type Ia sample and explore a methodology for calculating rates from the survey. We use individual SNLS survey epoch properties to observe Monte Carlo simulations of 106 Type Ia supernovae in the redshift range 0.2 < z < 0.6, and thus derive our survey efficiency. We combine this efficiency with a carefully selected control sample of spectroscopically confirmed SNLS Type Ia SNe to derive a volumetric rate. When comparing our volumetric rate with other ground-based surveys that also use spectroscopic candidate verification, we find no evidence for significant systematic underestimation of the SN Ia rates near z = 0.5. When comparing published SN Ia rates spanning the redshift range 0.0 < z < 1.6 to models of SN Ia production, we find that neither pure delay-time models nor two component models can accommodate all the observed data.

  3. IMPROVED DARK ENERGY CONSTRAINTS FROM {approx}100 NEW CfA SUPERNOVA TYPE Ia LIGHT CURVES

    SciTech Connect

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Wood-Vasey, W. Michael; Blondin, Stephane; Jha, Saurabh; Kelly, Patrick L.; Rest, Armin E-mail: kirshner@cfa.harvard.edu

    2009-08-01

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sup +0.066} {sub -0.068} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  4. Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves

    SciTech Connect

    Hicken, Malcolm; Wood-Vasey, W.Michael; Blondin, Stephane; Challis, Peter; Jha, Saurabh; Kelly, Patrick L.; Rest, Armin; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2012-04-06

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sub -0.068}{sup +0.066} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {Delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  5. Late-time spectra and type Ia supernova models: New clues from the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Ruiz-Lapuente, P.; Kirshner, R. P.; Phillips, M. M.; Challis, P. M.; Schmidt, B. P.; Filippenko, A. V.; Wheeler, J. C.

    1995-01-01

    Calculated late-time spectra of two classical hydrodynamical models for Type Ia supernovae (deflagration model W7 of Nomoto, Thielemann, & Yokoi, and delayed detonation model DD4 of Woosley & Weaver) are compared with observations of SN 1992A and other spectroscopically normal SNe Ia. An important new piece of information is provided by observations done with the Hubble Space Telescope (HST) which cover the ultraviolet range at the nebular phase of a SN Ia: SN 1992A in NGC 1380. For the first time a picture of SN Ia emission from the ultraviolet through the optical is obtained at these phases. Predictions of the classical model (W7 and DD4) are compared with the observed spectrum of SN 1992A and with the optical spectra of SN 1989M in NGC 4579 and SN 1990N in NGC 4639 at similar epochs. The absolute B and V magnitudes of the models are also estimated at these late phases. Taken at face value the nebular spectra of these 'classical' models are more consistent with the long extragalactic distance scale, pointing to distances to NGC 4579 around 21 +/- 3 Mpc and a slightly larger distance, 22 +/- 3 Mpc, to NGC 4639, on the back side of the Virgo Cluster. However, the calculated Fe(+3) luminosity as predicted from the models exceeds the observed limit from the HST data of SN 1992A. Other differences in the ratios of the line intensities between calculated and observed spectra, show some disagreement with the observed spectra at the nebular phases. They may not be the best choice for spectroscopically normal SNe Ia, and their use as an independent calibration of the extragalactic distance scale should be viewed with caution.

  6. The Type Ia supernova 1989B in NGC 3627 (M66)

    NASA Technical Reports Server (NTRS)

    Wells, Lisa A.; Phillips, M. M.; Suntzeff, Nicholas B.; Heathcote, S. R.; Hamuy, Mario; Navarrete, M.; Fernandez, M.; Weller, W. G.; Schommer, R. A.; Kirshner, Robert P.

    1994-01-01

    We report extensive optical photometry and spectroscopy of the Type Ia supernova 1989B. Maximum light in B occurred approximately seven days after discovery on JD 2447565.3 +/- 1.0 (1989 February 7.8 +/- 1.0) at a magnitude of 12.34 +/- 0.05. The UBV light curves of this supernova were very similar to those of other well observed Type Ia events such as SN 1981B and SN 1980N. From a comparison of the UBVRIJHK photometry, we derive an extinction for SN 1989B of E(B-V) = 0.37 +/- 0.03 mags relative to the unobscured Type Ia SN 1980N. The properties of the dust responsible for the reddening of SN 1989B appear to have been similar to those of normal dust in the Milky Way. In particular, we find no evidence for an unusually low value of the ratio of the total to selective absorption. We derive a distance modulus of delta mu(sub 0) = -1.62 +/- 0.03 mag relative to the Type Ia SN 1980N. We present optical spectra which provide essentially continuous coverage of the spectral evolution of SN 1989B over the first month following B maximum. These data show the transition from the maximum-light spectrum, in which lines of elements such as Ca, Si, S, Mg, and O are most prominent, to the Fe-dominated spectrum observed a few weeks after maximum. This transition occurred quite smoothly over a two-week period following B maximum. Comparison of the spectra of SN 1989B with data for two other well observed Type Ia supernovae -- 1981B and 1986G -- reveals subtle differences in the relative strengths of the S II and Si II absorption lines at maximum light. However, these differences disappeared within a week or so after maximum with the onset of the Fe-dominated phase.

  7. THE BIRTH RATE OF SNe Ia FROM HYBRID CONe WHITE DWARFS

    SciTech Connect

    Meng, Xiangcun; Podsiadlowski, Philipp

    2014-07-10

    Considering the uncertainties of the C-burning rate (CBR) and the treatment of convective boundaries, Chen et al. found that there is a regime where it is possible to form hybrid CONe white dwarfs (WDs), i.e., ONe WDs with carbon-rich cores. As these hybrid WDs can be as massive as 1.30 M {sub ☉}, not much mass needs to be accreted for these objects to reach the Chandrasekhar limit and to explode as Type Ia supernovae (SNe Ia). We have investigated their contribution to the overall SN Ia birth rate and found that such SNe Ia tend to be relatively young with typical time delays between 0.1 and 1 Gyr, where some may be as young as 30 Myr. SNe Ia from hybrid CONe WDs may contribute several percent to all SNe Ia, depending on the common-envelope ejection efficiency and the CBR. We suggest that these SNe Ia may produce part of the 2002cx-like SN Ia class.

  8. Delayed detonation models for normal and subluminous type Ia sueprnovae: Absolute brightness, light curves, and molecule formation

    NASA Technical Reports Server (NTRS)

    Hoflich, P.; Khokhlov, A. M.; Wheeler, J. C.

    1995-01-01

    We compute optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SN Ia's) using an elaborate treatment of the Local Thermodynamic Equilbrium (LTE) radiation transport, equation of state and ionization balance, expansion opacity including the cooling by CO, Co(+), and SiO, and a Monte Carlo gamma-ray deposition scheme. The models have an amount of Ni-56 in the range from approximately or equal to 0.1 solar mass up to 0.7 solar mass depending on the density at which the transition from a deflagration to a detonation occurs. Models with a large nickel production give light curves comparable to those of typical Type Ia supernovae. Subluminous supernovae can be explained by models with a low nickel production. Multiband light curves are presented in comparison with the normally bright event SN 1992bc and the subluminous events Sn 1991bg and SN 1992bo to establish the principle that the delayed detonation paradigm in Chandrasekhar mass models may give a common explosion mechanism accounting for both normal and subluminous SN Ia's. Secondary IR-maxima are formed in the models of normal SN Ia's as a photospheric effect if the photospheric radius continues to increase well after maximum light. Secondary maxima appear later and stronger in models with moderate expansion velocities and with radioactive material closer to the surface. Model light curves for subluminous SN Ia's tend to show only one 'late' IR-maximum. In some delayed detonation models shell-like envelopes form, which consist of unburned carbon and oxygen. The formation of molecules in these envelopes is addressed. If the model retains a C/O-envelope and is subluminous, strong vibration bands of CO may appear, typically several weeks past maximum light. CO should be very weak or absent in normal Sn Ia's.

  9. Nature versus Nurture: How Parent Galaxy Environments Affect the Rates and Properties of their Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Graham, Melissa Lynn

    2010-08-01

    Supernovae of Type Ia, SNe Ia, are currently the most powerful tool of modern cosmology, but their progenitor scenario is not yet well constrained. Recent studies of SN Ia rates in radio-loud early-type galaxies, and members of rich clusters, suggest a possible influence on SN Ia explosions outside of the established correlation with the age of the parent galaxy's stellar population (via the current specific star formation rate, sSFR). These rates were used to show that the characteristics of SN Ia progenitor systems may be inconsistent with theoretical expectations of the most popular scenarios. The astrophysical question of this thesis is: do parent galaxy and environment influence the rates and properties of Type Ia supernovae, and, if so, how? Towards this end, we combine the database of Type Ia supernovae from the Canada-France-Hawaii Telescope's Supernova Legacy Survey with publicly available catalogs including: galaxy photometric and spectroscopic redshifts, radio and infrared sources, and members of galaxy groups and clusters. This is the most comprehensive set of multi-wavelength host properties and environment parameters for intermediate redshift Type Ia supernovae yet compiled. We present the SNLS SN Ia rate per unit mass in a variety of parent galaxy and environment samples. We also statistically assess the probability of discrepancies between our rates, those of previous works at low redshift, rates in the general population of galaxies, and predictions of established empirical SN Ia rate models. In general, we do not find statistically significant evidence for SN Ia rate enhancements over the general population in galaxies which are radio-loud, infrared-bright, or associated with galaxy groups and clusters. In cases where we do find a suggestive rate enhancement, it is always with less than 2-sigma confidence. These rates agree with established empirical rate models, which in turn are consistent with theoretical expectations of the most plausible

  10. SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA

    SciTech Connect

    Piro, Anthony L.; Chang, Philip; Weinberg, Nevin N. E-mail: pchang@astro.berkeley.ed

    2010-01-01

    The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (approx20 keV) lasting approx10{sup -2} s with a total radiated energy of approx10{sup 40} erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M{sub V} approx -9 to -10 at approx1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of approx80 Mpc, giving a maximum rate of approx60 yr{sup -1}. Archival data sets can also be used to study the early rise dictated by the shock heating (at approx20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

  11. Formation of Dust in the Ejecta of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Nozawa, Takaya; Maeda, Keiichi; Kozasa, Takashi; Tanaka, Masaomi; Nomoto, Ken'ichi; Umeda, Hideyuki

    2011-07-01

    We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two extreme cases of the formation of CO and SiO molecules: complete formation and no formation. The results of the calculations show that for the sticking probability of α j = 1, C, silicate, Si, and FeS grains can condense at early times of ~100-300 days after the explosion, whereas Fe and SiC grains cannot form substantially. Due to the low gas density in SNe Ia with no H-envelope, the average radii of the newly formed grains are generally below 0.01 μm, being much smaller than those in Type II-P SNe. This supports our previous conclusion that the radius of dust formed in the ejecta is smaller in SNe with less massive envelopes. The total dust mass ranges from 3 × 10-4 M sun to 0.2 M sun for α j = 0.1-1, depending on whether or not CO and SiO molecules are formed. We also estimate the optical depths and thermal emission by the newly formed dust and compare them to the relevant observations of SNe Ia. We find that the formation of C grains in SNe Ia must be suppressed to be consistent with observational constraints. This implies that energetic photons and electrons heavily depress the formation efficiency of C grains or that the outermost C-O layer of SNe Ia is almost fully burned. Finally, we calculate dust destruction in the SN remnants and find that dust grains formed in the ejecta of SNe Ia are almost completely destroyed in the shocked gas before being injected into the interstellar medium. This indicates that SNe Ia are unlikely to be the major sources of interstellar dust.

  12. Type IA Supernovae and the Value of the Hubble Constant

    NASA Astrophysics Data System (ADS)

    Gibson, B. K.; Stetson, P. B.; Mould, J. R.; Kennicutt, R. C.; Freedman, W. L.; Huchra, J. P.; Sakai, S.; Graham, J. A.; Fassett, C. I.; Kelson, D. D.; Ferrarese, L.; Hughes, S. M. G.; Illingworth, G. D.; Macri, L. M.; Madore, B. F.; Sebo, K. M.; Silbermann, N. A.

    1999-05-01

    The primary observational task assigned the HST Key Project on the Extragalactic Distance Scale was the direct determination of distances to 18 nearby spirals via the search for, and discovery of, Cepheid variables. These galaxies provide the necessary calibration for secondary distance indicators such as the Tully-Fisher relation and Type Ia supernovae (SNe), thereby allowing a derivation of the Hubble Constant H_deg. Type Ia SNe are of particular importance as they (a) probe a regime in which complications due to the local flow field are minor, and (b) possess a Hubble Diagram intrinsic dispersion which is significantly smaller than other secondary indicators. Unfortunately, our original sample was ill-suited for calibrating the Type Ia SNe Hubble Diagram due to its lack of Type Ia SNe-host galaxies. Because of this shortcoming, an important parallel program was undertaken by our team which led to the incorporation of complementary datasets from the Sandage/Saha Type Ia SNe and Tanvir et al. Leo I Projects, into our Key Project sample. These two datasets provide an additional 7 galaxies for which Cepheid-based distances can be derived and, more importantly, each plays host to a Type Ia SN event. Following the identical precepts and software ``pipeline'' adopted throughout the Key Project, a re-analysis of this archive data was completed, ensuring homogeneity with that of the Key Project's photometry and distances. Our analysis of the local Type Ia SNe calibrators shows a systematic offset from the published Sandage/Saha and Tanvir et al. distances, resulting in a 10% larger H_deg, bringing empirical Type Ia SNe-based H_deg determinations into excellent agreement with those inferred via other secondary indicators. I will describe the philosophy and mechanics of our re-analysis program, highlighting the divergence from the earlier published results, and stress the implications for the derived value of the Hubble Constant.

  13. The Supernova Type Ia Rate Evolution with SNLS

    NASA Astrophysics Data System (ADS)

    Neill, James D.; Sullivan, M.; Balam, D.; Pritchet, C. J.; Howell, D. A.; Perrett, K.; Astier, P.; Aubourg, E.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Gonçalves, A. C.; Hardin, D.; Kowalski, M.; Lidman, C.; Lusset, V.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Schlegel, D.; Tao, C.

    2007-08-01

    We present a progress report on a project to derive the evolution of the volumetric supernova Type Ia rate from the Supernova Legacy Survey. Our preliminary estimate of the rate evolution divides the sample from Neill et al. into two redshift bins: 0.2 < z < 0.4, and 0.4 < z < 0.6. We extend this by adding a bin from the sample analyzed in Sullivan et al. in the range 0.6 < z < 0.75 from the same time period. We compare the derived trend with previously published rates and a supernova Type Ia production model having two components: one component associated closely with star formation and an additional component associated with host galaxy mass. Our observed trend is consistent with this model, which predicts a rising SN Ia rate out to at least z = 2.

  14. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    NASA Astrophysics Data System (ADS)

    Childress, Michael J.; Hillier, D. John; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D. Andrew; Inserra, Cosimo; Jha, Saurabh W.; Kumar, Sahana; Mazzali, Paolo A.; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W.; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D. R.; Yuan, Fang; Zhang, Bonnie

    2015-12-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of 56Ni to 56Co at early times, and the decay of 56Co to 56Fe from ˜60 d after explosion. We examine the evolution of the [Co III] λ5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of 56Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in 56Co decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [Co III] λ5893 line and remove its well-behaved time dependence to infer the initial mass of 56Ni (MNi) produced in the explosion. We then examine 56Ni yields for different SN Ia ejected masses (Mej - calculated using the relation between light-curve width and ejected mass) and find that the 56Ni masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s ˜ 0.7-0.9), MNi is clustered near MNi ≈ 0.4 M⊙ and shows a shallow increase as Mej increases from ˜1 to 1.4 M⊙; at high stretch, Mej clusters at the Chandrasekhar mass (1.4 M⊙) while MNi spans a broad range from 0.6 to 1.2 M⊙. This could constitute evidence for two distinct SN Ia explosion mechanisms.

  15. Type Ia supernovae: explosions and progenitors

    NASA Astrophysics Data System (ADS)

    Kerzendorf, Wolfgang Eitel

    2011-08-01

    Supernovae are the brightest explosions in the universe. Supernovae in our Galaxy, rare and happening only every few centuries, have probably been observed since the beginnings of mankind. At first they were interpreted as religious omens but in the last half millennium they have increasingly been used to study the cosmos and our place in it. Tycho Brahe deduced from his observations of the famous supernova in 1572, that the stars, in contrast to the widely believe Aristotelian doctrine, were not immutable. More than 400 years after Tycho made his paradigm changing discovery using SN 1572, and some 60 years after supernovae had been identified as distant dying stars, two teams changed the view of the world again using supernovae. The found that the Universe was accelerating in its expansion, a conclusion that could most easily be explained if more than 70% of the Universe was some previously un-identified form of matter now often referred to as `Dark Energy'. Beyond their prominent role as tools to gauge our place in the Universe, supernovae themselves have been studied well over the past 75 years. We now know that there are two main physical causes of these cataclysmic events. One of these channels is the collapse of the core of a massive star. The observationally motivated classes Type II, Type Ib and Type Ic have been attributed to these events. This thesis, however is dedicated to the second group of supernovae, the thermonuclear explosions of degenerate carbon and oxygen rich material and lacking hydrogen - called Type Ia supernovae (SNe Ia). White dwarf stars are formed at the end of a typical star's life when nuclear burning ceases in the core, the outer envelope is ejected, with the degenerate core typically cooling for eternity. Theory predicts that such stars will self ignite when close to 1.38 Msun (called the Chandrasekhar Mass). Most stars however leave white dwarfs with 0.6 Msun, and no star leaves a remnant as heavy as 1.38 M! sun, which suggests

  16. Interleukin-induced increase in Ia expression by normal mouse B cells

    PubMed Central

    1984-01-01

    The constitutive culture supernatant (SN) of the macrophage tumor line P388D1 (P388 SN) and the concanavalin A (Con A)-induced culture supernatant of the T cell hybridoma FS6-14.13 (FS6 Con A SN) were shown to contain nonspecific factors capable of inducing increased Ia expression by normal resting B cells in a dose-dependent manner. In six consecutive experiments the relative increase in Ia expression induced by P388 SN was 4.9 +/- 0.9, with FS6 Con A SN 10.7 +/- 1.5, and with a combination of both preparations 13.0 +/- 1.7. This increase in Ia expression was observed to occur in virtually all the B cells, reaching maximum levels within 24 h of culture. The interleukin-induced increase in B cell Ia expression occurred in the absence of ancillary signals provided by ligand-receptor Ig cross-linking and despite the fact that virtually all the control B cells, cultured in the absence of factors, remained in G0. These results suggest that functional receptors for at least some interleukins are expressed on normal resting B cells and their effects can be manifest in the absence of additional activating signals. The increased Ia expression induced by the nonspecific factor preparations was shown to be correlated with enhanced antigen- presenting capacity by the B cells to T cell hybridomas. The nature of the interleukins responsible for these effects remains to be definitively determined, however, the activity of FS6 Con A SN was shown to correlate with B cell growth factor activity and increased B cell Ia expression was not observed using interleukin 2 (IL-2) or interferon-gamma, prepared by recombinant DNA technology. PMID:6432933

  17. The Link Between RS Ophiuchi and Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Mohamed, S.; Booth, R.; Podsiadlowski, Ph.

    2013-01-01

    RS Ophiuchi (RS Oph) is a symbiotic nova system consisting of a red giant and an accreting white dwarf (WD) which undergoes thermonuclear outbursts every 10-20 years. The WD is thought to be close to the Chandrasekhar mass making the system a likely Type Ia supernova (SN Ia) candidate. In recent years, the RS Oph-SN Ia connection has been further strengthened by time-varying circumstellar (CSM) absorption lines observed in high-resolution spectra of both systems. In this paper, we present 3D hydrodynamic simulations of the RS Oph system and preliminary post-processing results for the CSM absorption and hydrogen recombination lines. We find good agreement between the highly-structured, bipolar geometry in our models and the observed morphology. The geometry also naturally explains both the low velocity, narrow absorption and broad emission lines seen in SN 2006X and PTF 11kx. However, we find longer recombination timescales, larger velocity widths and weaker lines suggesting that the shells may be thinner and denser than those in our simulations.

  18. SN X-ray Progenitor?

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Identifying stars that explode, right before they explode, is a tricky proposition since the end of starlife comes swiftly: in thermonuclear deflagrations, in nuclear exhaustion, or maybe in a rapid swirling merger of two dead stellar cores. On the right in the image above is an image of the galaxy NGC 1404 taken by the UV/optical Telescope (UVOT) on the Swift observatory. The circle surrounds SN 2007on, a supernova of Type Ia produced by the explosion of a white dwarf star in a binary system. These types of supernovae are important since they are believed to be 'standard candles', events which have the same intrinsic brightness which can serve as an important yardstick to measure cosmic distances. On the left is an image of the same galaxy taken by the Chandra X-ray observatory four years before the supernova. Conspicuous in the SN source circle is a bright source in the Chandra image, believed to be emission from a compact object+normal star companion: a similar system to the supposed precursor of SN 2007on. If true this would be the first time a Type Ia supernova precursor has ever been seen. But astronomers are still debating whether the Chandra source really is the precursor or not; it seems there's a slight but significant difference in the location of the Chandra source and the supernova. Stay tuned for more developments.

  19. Comparative analysis of SN 2012dn optical spectra: days -14 to +114

    NASA Astrophysics Data System (ADS)

    Parrent, J. T.; Howell, D. A.; Fesen, R. A.; Parker, S.; Bianco, F. B.; Dilday, B.; Sand, D.; Valenti, S.; Vinkó, J.; Berlind, P.; Challis, P.; Milisavljevic, D.; Sanders, N.; Marion, G. H.; Wheeler, J. C.; Brown, P.; Calkins, M. L.; Friesen, B.; Kirshner, R.; Pritchard, T.; Quimby, R.; Roming, P.

    2016-04-01

    SN 2012dn is a super-Chandrasekhar mass candidate in a purportedly normal spiral (SAcd) galaxy, and poses a challenge for theories of type Ia supernova diversity. Here we utilize the fast and highly parametrized spectrum synthesis tool, SYNAPPS, to estimate relative expansion velocities of species inferred from optical spectra obtained with six facilities. As with previous studies of normal SN Ia, we find that both unburned carbon and intermediate-mass elements are spatially coincident within the ejecta near and below 14 000 km s-1. Although the upper limit on SN 2012dn's peak luminosity is comparable to some of the most luminous normal SN Ia, we find a progenitor mass exceeding ˜1.6 M⊙ is not strongly favoured by leading merger models since these models do not accurately predict spectroscopic observations of SN 2012dn and more normal events. In addition, a comparison of light curves and host-galaxy masses for a sample of literature and Palomar Transient Factory SN Ia reveals a diverse distribution of SN Ia subtypes where carbon-rich material remains unburned in some instances. Such events include SN 1991T, 1997br, and 1999aa where trace signatures of C III at optical wavelengths are presumably detected.

  20. SOME CONSTRAINTS ON THE LOWER MASS LIMIT FOR DOUBLE-DEGENERATE PROGENITORS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Chen, X.; Han, Z.

    2012-08-10

    Recent theoretical and observational studies both argue that the merging of double carbon-oxygen white dwarfs (WDs) is responsible for at least some Type Ia supernovae (SNe Ia). Previous (standard) studies of the anticipated SN birthrate from this channel have assumed that the merger process is conservative and that the primary criterion for explosion is that the merged mass exceeds the Chandrasekhar mass. Han and Webbink demonstrated that mass transfer and merger in close double WDs will in many cases be non-conservative. Pakmor et al. further suggested that the merger process should be violent in order to initiate an explosion. We have therefore investigated how the SN Ia birthrate from the double-degenerate (DD) channel is affected by these constraints. Using the binary-star population-synthesis method, we have calculated the DD SN Ia birthrate under conservative and non-conservative approximations, and including lower mass and mass-ratio limits indicated by recent smoothed-particle-hydrodynamic calculations. The predicted DD SN Ia rate is significantly reduced by all of these constraints. With dynamical mass loss alone (violent merger) the birthrate is reduced to 56% of the conservative rate. Requiring the mass ratio q > 2/3 further reduces the birthrate to 18% that of the standard assumption. An upper limit of 0.0061 SNuM, or a Galactic rate of 4.6 Multiplication-Sign 10{sup -4} yr{sup -1}, might be realistic.

  1. Cosmological Parameter Uncertainties from SALT-II Type Ia Supernova Light Curve Models

    SciTech Connect

    Mosher, J.; Guy, J.; Kessler, R.; Astier, P.; Marriner, J.; Betoule, M.; Sako, M.; El-Hage, P.; Biswas, R.; Pain, R.; Kuhlmann, S.; Regnault, N.; Frieman, J. A.; Schneider, D. P.

    2014-08-29

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ~120 low-redshift (z < 0.1) SNe Ia, ~255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ~290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w (input) – w (recovered)) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty, the average bias on w is –0.014 ± 0.007.

  2. Cosmological parameter uncertainties from SALT-II type Ia supernova light curve models

    SciTech Connect

    Mosher, J.; Sako, M.; Guy, J.; Astier, P.; Betoule, M.; El-Hage, P.; Pain, R.; Regnault, N.; Marriner, J.; Biswas, R.; Kuhlmann, S.; Schneider, D. P.

    2014-09-20

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ∼120 low-redshift (z < 0.1) SNe Ia, ∼255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ∼290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w {sub input} – w {sub recovered}) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty; the average bias on w is –0.014 ± 0.007.

  3. THE SUBLUMINOUS AND PECULIAR TYPE Ia SUPERNOVA PTF 09dav

    SciTech Connect

    Sullivan, M.; Ofek, E. O.; Blake, S.; Podsiadlowski, P.; Kasliwal, M. M.; Cooke, J.; Quimby, R.; Kulkarni, S. R.; Nugent, P. E.; Thomas, R. C.; Poznanski, D.; Howell, D. A.; Arcavi, I.; Gal-Yam, A.; Hook, I. M.; Mazzali, P.; Bildsten, L.; Bloom, J. S.; Cenko, S. B.; Law, N.

    2011-05-10

    PTF 09dav is a peculiar subluminous Type Ia supernova (SN) discovered by the Palomar Transient Factory (PTF). Spectroscopically, it appears superficially similar to the class of subluminous SN1991bg-like SNe, but it has several unusual features which make it stand out from this population. Its peak luminosity is fainter than any previously discovered SN1991bg-like SN Ia (M{sub B} {approx} -15.5), but without the unusually red optical colors expected if the faint luminosity were due to extinction. The photospheric optical spectra have very unusual strong lines of Sc II and Mg I, with possible Sr II, together with stronger than average Ti II and low velocities of {approx}6000 km s{sup -1}. The host galaxy of PTF09dav is ambiguous. The SN lies either on the extreme outskirts ({approx}41 kpc) of a spiral galaxy or in an very faint (M{sub R} {>=} -12.8) dwarf galaxy, unlike other 1991bg-like SNe which are invariably associated with massive, old stellar populations. PTF 09dav is also an outlier on the light-curve-width-luminosity and color-luminosity relations derived for other subluminous SNe Ia. The inferred {sup 56}Ni mass is small (0.019 {+-} 0.003 M{sub sun}), as is the estimated ejecta mass of 0.36 M{sub sun}. Taken together, these properties make PTF 09dav a remarkable event. We discuss various physical models that could explain PTF 09dav. Helium shell detonation or deflagration on the surface of a CO white dwarf can explain some of the features of PTF 09dav, including the presence of Sc and the low photospheric velocities, but the observed Si and Mg are not predicted to be very abundant in these models. We conclude that no single model is currently capable of explaining all of the observed signatures of PTF 09dav.

  4. [O I] λλ6300, 6364 IN THE NEBULAR SPECTRUM OF A SUBLUMINOUS TYPE Ia SUPERNOVA

    SciTech Connect

    Taubenberger, S.; Kromer, M.; Hillebrandt, W.; Pakmor, R.; Pignata, G.; Maeda, K.; Hachinger, S.; Leibundgut, B.

    2013-10-01

    In this Letter, a late-phase spectrum of SN 2010lp, a subluminous Type Ia supernova (SN Ia), is presented and analyzed. As in 1991bg-like SNe Ia at comparable epochs, the spectrum is characterized by relatively broad [Fe II] and [Ca II] emission lines. However, instead of narrow [Fe III] and [Co III] lines that dominate the emission from the innermost regions of 1991bg-like supernovae (SNe), SN 2010lp shows [O I] λλ6300, 6364 emission, usually associated with core-collapse SNe and never previously observed in a subluminous thermonuclear explosion. The [O I] feature has a complex profile with two strong, narrow emission peaks. This suggests that oxygen is distributed in a non-spherical region close to the center of the ejecta, severely challenging most thermonuclear explosion models discussed in the literature. We conclude that, given these constraints, violent mergers are presently the most promising scenario to explain SN 2010lp.

  5. SN 2008ha: AN EXTREMELY LOW LUMINOSITY AND EXCEPTIONALLY LOW ENERGY SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Kirshner, Robert P.; Challis, Peter J.; Friedman, Andrew S.; Chornock, Ryan; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Cenko, S. Bradley; Modjaz, Maryam; Silverman, Jeffrey M.; Wood-Vasey, W. Michael

    2009-08-15

    We present ultraviolet, optical, and near-infrared photometry as well as optical spectra of the peculiar supernova (SN) 2008ha. SN 2008ha had a very low peak luminosity, reaching only M{sub V} = -14.2 mag, and low line velocities of only {approx}2000 km s{sup -1} near maximum brightness, indicating a very small kinetic energy per unit mass of ejecta. Spectroscopically, SN 2008ha is a member of the SN 2002cx-like class of SNe, a peculiar subclass of SNe Ia; however, SN 2008ha is the most extreme member, being significantly fainter and having lower line velocities than the typical member, which is already {approx}2 mag fainter and has line velocities {approx}5000 km s{sup -1} smaller (near maximum brightness) than a normal SN Ia. SN 2008ha had a remarkably short rise time of only {approx}10 days, significantly shorter than either SN 2002cx-like objects ({approx}15 days) or normal SNe Ia ({approx}19.5 days). The bolometric light curve of SN 2008ha indicates that SN 2008ha peaked at L {sub peak} = (9.5 {+-} 1.4) x 10{sup 40} erg s{sup -1}, making SN 2008ha perhaps the least luminous SN ever observed. From its peak luminosity and rise time, we infer that SN 2008ha generated (3.0 {+-} 0.9) x 10{sup -3} M {sub sun} of {sup 56}Ni, had a kinetic energy of {approx}2 x 10{sup 48} erg, and ejected 0.15 M {sub sun} of material. The host galaxy of SN 2008ha has a luminosity, star formation rate, and metallicity similar to those of the Large magellanic Cloud. We classify three new (and one potential) members of the SN 2002cx-like class, expanding the sample to 14 (and one potential) members. The host-galaxy morphology distribution of the class is consistent with that of SNe Ia, Ib, Ic, and II. Several models for generating low-luminosity SNe can explain the observations of SN 2008ha; however, if a single model is to describe all SN 2002cx-like objects, deflagration of carbon-oxygen white dwarfs, with SN 2008ha being a partial deflagration and not unbinding the progenitor star, is

  6. Swift X-Ray Upper Limits on Type Ia Supernova Environments

    NASA Technical Reports Server (NTRS)

    Russell, B. R.; Immler, S.

    2012-01-01

    We have considered 53 Type Ia supernovae (SNe Ia) observed by the Swift X-Ray Telescope. None of the SNe Ia are individually detected at any time or in stacked images. Using these data and assuming that the SNe Ia are a homogeneous class of objects, we have calculated upper limits to the X-ray luminosity (0.2-10 keV) and mass-loss rate of L(sub 0.2-10) < 1.7 X 10(exp 38) erg/s and M(dot) < l.l X 10(exp -6) solar M/ yr x (V(sub w))/(10 km/s), respectively. The results exclude massive or evolved stars as the companion objects in SN Ia progenitor systems, but allow the possibility of main sequence or small stars, along with double degenerate systems consisting of two white dwarfs, consistent with results obtained at other wavelengths (e.g., UV, radio) in other studies.

  7. NEBULAR SPECTRA AND EXPLOSION ASYMMETRY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Maeda, K.; Nomoto, K.; Taubenberger, S.; Mazzali, P.A.; Sollerman, J.; Leloudas, G.; Motohara, K.

    2010-01-10

    The spectral signatures of asymmetry in Type Ia Supernova (SN Ia) explosions are investigated, using a sample of late-time nebular spectra. First, a kinematical model is constructed for SN Ia 2003hv, which can account for the main features in its optical, Near-Infrared (NIR), and Mid-Infrared (Mid-IR) late-time spectra. It is found that an asymmetric off-center model can explain the observed characteristics of SN 2003hv. This model includes a relatively high-density, Fe-rich region which displays a large velocity off-set, and a relatively low density, extended {sup 56}Ni-rich region which is more spherically distributed. The high-density region consists of the inner stable Fe-Ni region and outer {sup 56}Ni-rich region. Such a distribution may be the result of a delayed-detonation explosion, in which the first deflagration produces the global asymmetry in the innermost ejecta, while the subsequent detonation can lead to the bulk spherical symmetry. This configuration, if viewed from the direction of the off-set, can consistently explain the blueshift in some of the emission lines and virtually no observed shift in other lines in SN 2003hv. For this model, we then explore the effects of different viewing angles and the implications for SNe Ia in general. The model predicts that a variation of the central wavelength, depending on the viewing angle, should be seen in some lines (e.g., [Ni II] lambda7378), while the strongest lines (e.g., [Fe III] blend at approx4700 A) will not show this effect. By examining optical nebular spectra of 12 SNe Ia, we have found that such a variation indeed exists. We suggest that the global asymmetry in the innermost ejecta, as likely imprint of the deflagration flame propagation, is a generic feature of SNe Ia. It is also shown that various forbidden lines in the NIR and Mid-IR regimes provide strong diagnostics to further constrain the explosion geometry and thus the explosion mechanism.

  8. Measurements of the Rate of Type Ia Supernovae at Redshift z < ~0.3 from the SDSS-II Supernova Survey

    SciTech Connect

    Dilday, Benjamin; Smith, Mathew; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Filippenko, Alexei V.; Frieman, Joshua A.; Galbany, Lluis; Garnavich, Peter M.; /Notre Dame U. /Stockholm U., OKC /Stockholm U.

    2010-01-01

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z {approx}< 0.3, of which 270 (52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04{sub -0.95}{sup +1.61}% of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume a SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of r{sub V} = (2.69{sub -0.30-0.01}{sup +0.34+0.21}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} at a mean redshift of {approx} 0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, r{sub V} (z) = A{sub p} x ((1+z)/(1+z{sub 0})){sup {nu}}, over the redshift range 0.0 < z < 0.3 with z{sub 0} = 0.21, results in A{sub p} = (3.43{sub -0.15}{sup +0.15}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} and {nu} = 2.04{sub -0.89}{sup +0.90}.

  9. Velocity Evolution and the Intrinsic Color of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan J.; Sanders, Nathan E.; Kirshner, Robert P.

    2011-12-01

    To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of Si II λ6355 and Ca II H&K are related to the B - V color at peak brightness. We find that the maximum-light velocity of Si II λ6355 and Ca II H&K and the maximum-light pseudo-equivalent width of Si II λ6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the Si II λ6355 measurements. Ca II H&K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia—even after removing a linear trend with velocity—indicating that lower-velocity SNe Ia are more "standard crayons." Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.

  10. SweetSpot Data Release 1: 70 Type Ia Supernovae in the Near Infrared in the Nearby Hubble Flow

    NASA Astrophysics Data System (ADS)

    Wood-Vasey, W. Michael; Weyant, Anja; Allen, Lori; Trevino Barton, Nathan; Garnavich, Peter M.; Farhin Jahan, Nabila; Jha, Saurabh; Kroboth, Jessica Rose; Ponder, Kara Ann; Joyce, Richard R.; Matheson, Thomas; Rest, Armin

    2015-01-01

    SweetSpot is an NOAO Survey program from 2012B-2015A that is observing 150 Type Ia supernovae (SNeIa) in the Hubble flow to obtain reliable NIR luminosities free from peculiar-velocity confusion and the uncertainties of dust.Our full SweetSpot program will (1) extend the NIR Hubble diagram past currently available samples; (2) quantitatively demonstrate the degree to which SNeIa are robust standard candles in the NIR; (3) provide key insights about the color evolution and intrinsic properties of SNeIa and their host galaxies; and (4) establish a well-calibrated low-redshift anchor for future NIR supernova surveys from JWST, Euclid, and WFIRST/NEW. By the end of the survey we will have measured the relative distance to a redshift of z~0.05 to 1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNeIa in the restframe NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.We here present our Data Release 1 which includes 70 supernovae observed from 2011B-2013B. Along with an updated NIR Hubble diagram combining these SNeIa with those from the literature, we explore the relationships between SNIa NIR luminosity and properties of the host galaxy.

  11. Rapidly Decaying Supernova 2010X: A Candidate ".Ia" Explosion

    NASA Astrophysics Data System (ADS)

    Kasliwal, Mansi M.; Kulkarni, S. R.; Gal-Yam, Avishay; Yaron, Ofer; Quimby, Robert M.; Ofek, Eran O.; Nugent, Peter; Poznanski, Dovi; Jacobsen, Janet; Sternberg, Assaf; Arcavi, Iair; Howell, D. Andrew; Sullivan, Mark; Rich, Douglas J.; Burke, Paul F.; Brimacombe, Joseph; Milisavljevic, Dan; Fesen, Robert; Bildsten, Lars; Shen, Ken; Cenko, S. Bradley; Bloom, Joshua S.; Hsiao, Eric; Law, Nicholas M.; Gehrels, Neil; Immler, Stefan; Dekany, Richard; Rahmer, Gustavo; Hale, David; Smith, Roger; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Kahnh; McKenna, Dan

    2010-11-01

    We present the discovery, photometric, and spectroscopic follow-up observations of SN 2010X (PTF 10bhp). This supernova decays exponentially with τ d = 5 days and rivals the current recordholder in speed, SN 2002bj. SN 2010X peaks at M r = -17 mag and has mean velocities of 10,000 km s-1. Our light curve modeling suggests a radioactivity-powered event and an ejecta mass of 0.16 M sun. If powered by Nickel, we show that the Nickel mass must be very small (≈0.02 M sun) and that the supernova quickly becomes optically thin to γ-rays. Our spectral modeling suggests that SN 2010X and SN 2002bj have similar chemical compositions and that one of aluminum or helium is present. If aluminum is present, we speculate that this may be an accretion-induced collapse of an O-Ne-Mg white dwarf. If helium is present, all observables of SN 2010X are consistent with being a thermonuclear helium shell detonation on a white dwarf, a ".Ia" explosion. With the 1 day dynamic-cadence experiment on the Palomar Transient Factory, we expect to annually discover a few such events.

  12. PROSPECT OF STUDYING HARD X- AND GAMMA-RAYS FROM TYPE Ia SUPERNOVAE

    SciTech Connect

    Maeda, K.; Nomoto, K.; Terada, Y.; Kasen, D.; Roepke, F. K.; Seitenzahl, I. R.; Bamba, A.; Diehl, R.; Kromer, M.; Hillebrandt, W.; Yamaguchi, H.; Tamagawa, T.

    2012-11-20

    We perform multi-dimensional, time-dependent radiation transfer simulations for hard X-ray and {gamma}-ray emissions, following radioactive decays of {sup 56}Ni and {sup 56}Co, for two-dimensional delayed-detonation models of Type Ia supernovae (SNe Ia). The synthetic spectra and light curves are compared with the sensitivities of current and future observatories for an exposure time of 10{sup 6} s. The non-detection of the {gamma}-ray signal from SN 2011fe at 6.4 Mpc by SPI on board INTEGRAL places an upper limit on the mass of {sup 56}Ni of {approx}< 1.0 M {sub Sun }, independently from observations in any other wavelengths. Signals from the newly formed radioactive species have not yet been convincingly measured from any SN Ia, but future X-ray and {gamma}-ray missions are expected to deepen the observable horizon to provide high energy emission data for a significant SN Ia sample. We predict that the hard X-ray detectors on board NuStar (launched in 2012) or ASTRO-H (scheduled for launch in 2014) will reach to SNe Ia at {approx}15 Mpc, i.e., one SN every few years. Furthermore, according to the present results, the soft {gamma}-ray detector on board ASTRO-H will be able to detect the 158 keV line emission up to {approx}25 Mpc, i.e., a few SNe Ia per year. Proposed next-generation {gamma}-ray missions, e.g., GRIPS, could reach to SNe Ia at {approx}20-35 Mpc by MeV observations. Those would provide new diagnostics and strong constraints on explosion models, detecting rather directly the main energy source of supernova light.

  13. Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra

    SciTech Connect

    Nugent, Peter E; Ellis, R.S.; Sullivan, M.; Nugent, P.E.; Howell, D.A.; Gal-Yam, A.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I.; Pain, R.; Perrett, K.; Pritchet, C.J.; Regnault, N.

    2008-02-28

    We analyze the mean rest-frame ultraviolet (UV) spectrum of Type Ia Supernovae (SNe) and its dispersion using high signal-to-noise ratio Keck-I/LRIS-B spectroscopy for a sample of 36 events at intermediate redshift (z=0.5) discovered by the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We introduce a new method for removing host galaxy contamination in our spectra, exploiting the comprehensive photometric coverage of the SNLS SNe and their host galaxies, thereby providing the first quantitative view of the UV spectral properties of a large sample of distant SNe Ia. Although the mean SN Ia spectrum has not evolved significantly over the past 40percent of cosmic history, precise evolutionary constraints are limited by the absence of a comparable sample of high-quality local spectra. The mean UV spectrum of our z~;;=0.5 SNe Ia and its dispersion is tabulated for use in future applications. Within the high-redshift sample, we discover significant UV spectral variations and exclude dust extinction as the primary cause by examining trends with the optical SN color. Although progenitor metallicity may drive some of these trends, the variations we see are much larger than predicted in recent models and do not follow expected patterns. An interesting new result is a variation seen in the wavelength of selected UV features with phase. We also demonstrate systematic differences in the SN Ia spectral features with SN light curve width in both the UV and the optical. We show that these intrinsic variations could represent a statistical limitation in the future use of high-redshift SNe Ia for precision cosmology. We conclude that further detailed studies are needed, both locally and at moderate redshift where the rest-frame UV can be studied precisely, in order that future missions can confidently be planned to fully exploit SNe Ia as cosmological probes.

  14. Cosmology with Photometrically Classified Type Ia Supernovae from the SDSS-II Supernova Survey

    NASA Astrophysics Data System (ADS)

    Campbell, Heather; D'Andrea, Chris B.; Nichol, Robert C.; Sako, Masao; Smith, Mathew; Lampeitl, Hubert; Olmstead, Matthew D.; Bassett, Bruce; Biswas, Rahul; Brown, Peter; Cinabro, David; Dawson, Kyle S.; Dilday, Ben; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W.; Kuhlmann, Steve; Kunz, Martin; Marriner, John; Miquel, Ramon; Richmond, Michael; Riess, Adam; Schneider, Donald P.; Sollerman, Jesper; Taylor, Matt; Zhao, Gong-Bo

    2013-02-01

    We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting to a flat ΛCDM cosmological model, we find that our photometric sample alone gives Ω m = 0.24+0.07 -0.05 (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on Ω m and ΩΛ, comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H 0, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96+0.10 -0.10, Ω m = 0.29+0.02 -0.02, and Ω k = 0.00+0.03 -0.02 (statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.

  15. Use of near infrared spectra to probe the chemical structure of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Marion, George Howard

    2006-08-01

    Type Ia Supernovae (SNe Ia) are intrinsically interesting as very large explosions involving extreme and exotic physics. SNe Ia have become important cosmologically because their relative uniformity and high luminosity make them effective "standard candles" for distance estimates at large redshifts. We identified the near infrared (NIR; 0.8--2.5 mum) as a nearly unexplored and potentially very productive region for SNe Ia research. The NIR is a rich source of information about many explosion products that are obscured or blended at other wavelengths. We designed and implemented a systematic program to obtain NIR spectra from SNe Ia. We developed new tools and techniques to acquire, process, and interpret the data. We used synthetic models of SNe Ia explosions to aid the interpretation of results, and we used the observations to constrain the models. We obtained a large data set of NIR spectra that permits us to make important deductions about the chemical structure of SNe Ia. We show that NIR spectra have a uniform spectral evolution for normal SNe Ia. Thus our sample of forty-one spectra can be arranged in a time series to probe the chemical structure from the outer layers to deep inside the SN. We show that the burning products reside in distinct layers with no large scale mixing. We use multiple methods to demonstrate that burning consumes nearly the entire progenitor, making the amount of fuel the same for all SNe Ia explosions. That helps explain the homogeneity of SNe Ia. The two most popular explosion models produce different results that are detectable in the NIR. Our discoveries about the physical structure of SNe Ia agree well with the predictions of delayed detonation (DD) explosion models. Pure deflagration models are directly contradicted by our results and merger models are disfavored. Our results open the NIR window for SNe Ia research and we propose future directions for this field.

  16. Lensed Type Ia supernovae as probes of cluster mass models

    NASA Astrophysics Data System (ADS)

    Nordin, J.; Rubin, D.; Richard, J.; Rykoff, E.; Aldering, G.; Amanullah, R.; Atek, H.; Barbary, K.; Deustua, S.; Fakhouri, H. K.; Fruchter, A. S.; Goobar, A.; Hook, I.; Hsiao, E. Y.; Huang, X.; Kneib, J.-P.; Lidman, C.; Meyers, J.; Perlmutter, S.; Saunders, C.; Spadafora, A. L.; Suzuki, N.; Supernova Cosmology Project

    2014-05-01

    Using three magnified Type Ia supernovae (SNe Ia) detected behind CLASH (Cluster Lensing and Supernovae with Hubble) clusters, we perform a first pilot study to see whether standardizable candles can be used to calibrate cluster mass maps created from strong lensing observations. Such calibrations will be crucial when next-generation Hubble Space Telescope cluster surveys (e.g. Frontier) provide magnification maps that will, in turn, form the basis for the exploration of the high-redshift Universe. We classify SNe using combined photometric and spectroscopic observations, finding two of the three to be clearly of Type Ia and the third probable. The SNe exhibit significant amplification, up to a factor of 1.7 at ˜5σ significance (SN-L2). We conducted this as a blind study to avoid fine-tuning of parameters, finding a mean amplification difference between SNe and the cluster lensing models of 0.09 ± 0.09stat ± 0.05sys mag. This impressive agreement suggests no tension between cluster mass models and high-redshift-standardized SNe Ia. However, the measured statistical dispersion of σμ = 0.21 mag appeared large compared to the dispersion expected based on statistical uncertainties (0.14). Further work with the SN and cluster lensing models, post-unblinding, reduced the measured dispersion to σμ = 0.12. An explicit choice should thus be made as to whether SNe are used unblinded to improve the model, or blinded to test the model. As the lensed SN samples grow larger, this technique will allow improved constraints on assumptions regarding e.g. the structure of the dark matter halo.

  17. Sweetspot: Near-infrared observations of 13 type Ia supernovae from a new NOAO survey probing the nearby smooth Hubble flow

    SciTech Connect

    Weyant, Anja; Wood-Vasey, W. Michael; Allen, Lori; Joyce, Richard; Matheson, Thomas; Garnavich, Peter M.; Jha, Saurabh W.

    2014-04-01

    We present 13 Type Ia supernovae (SNe Ia) observed in the rest-frame near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera on the WIYN 3.5 m telescope. With only one to three points per light curve and a prior on the time of maximum from the spectrum used to type the object, we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in an H band, even with limited data. Our sample includes two SNe Ia at z ∼ 0.09, which represent the most distant rest-frame NIR H-band observations published to date. This modest sample of 13 NIR SNe Ia represent the pilot sample for {sup S}weetSpot{sup —}a 3 yr NOAO Survey program that will observe 144 SNe Ia in the smooth Hubble flow. By the end of the survey we will have measured the relative distance to a redshift of z ∼ 0.05%-1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNe Ia in the rest-frame NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.

  18. THE MOST SLOWLY DECLINING TYPE Ia SUPERNOVA 2001ay

    SciTech Connect

    Krisciunas, Kevin; Gooding, Samuel D.; Li Weidong E-mail: sam.gooding86@gmail.com

    2011-09-15

    We present optical and near-infrared photometry, as well as ground-based optical spectra and Hubble Space Telescope ultraviolet spectra, of the Type Ia supernova (SN) 2001ay. At maximum light the Si II and Mg II lines indicated expansion velocities of 14,000 km s{sup -1}, while Si III and S II showed velocities of 9000 km s{sup -1}. There is also evidence for some unburned carbon at 12,000 km s{sup -1}. SN 2001ay exhibited a decline-rate parameter of {Delta}m{sub 15}(B) = 0.68 {+-} 0.05 mag; this and the B-band photometry at t {approx}> +25 day past maximum make it the most slowly declining Type Ia SN yet discovered. Three of the four super-Chandrasekhar-mass candidates have decline rates almost as slow as this. After correction for Galactic and host-galaxy extinction, SN 2001ay had M{sub B} = -19.19 and M{sub V} = -19.17 mag at maximum light; thus, it was not overluminous in optical bands. In near-infrared bands it was overluminous only at the 2{sigma} level at most. For a rise time of 18 days (explosion to bolometric maximum) the implied {sup 56}Ni yield was (0.58 {+-} 0.15)/{alpha} M{sub sun}, with {alpha} = L{sub max}/E{sub Ni} probably in the range 1.0-1.2. The {sup 56}Ni yield is comparable to that of many Type Ia SNe. The 'normal' {sup 56}Ni yield and the typical peak optical brightness suggest that the very broad optical light curve is explained by the trapping of {gamma} rays in the inner regions.

  19. On the Dependence of  Type Ia SNe Luminosities on the Metallicity of Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.; Galbany, Lluís; Vílchez, José Manuel; Carnero Rosell, Aurelio; Domínguez, Inmaculada

    2016-02-01

    The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence MB–Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.

  20. FLOYDS Classification of ASASSN-14lo as a Type Ia Supernova Near Peak

    NASA Astrophysics Data System (ADS)

    Arcavi, Iair; Sand, David; McCully, Curtis; Valenti, Stefano; Hosseinzadeh, Griffin; Howell, D. Andrew

    2014-12-01

    We obtained a spectrum of ASASSN-14lo (ATel #6794) on 2014 December 10 (UT) with the robotic FLOYDS instrument mounted on the Faulkes Telescope North. Using Superfit (Howell et al. 2005, ApJ 634, 1190) we find a good fit to the Type Ia SN 1996X around peak at the redshift of the proposed host galaxy (z=0.01993; NED).

  1. ASASSN-16av: Discovery of A Type Ia Supernova in NGC 3926 NED02

    NASA Astrophysics Data System (ADS)

    Holoien, T. W.-S.; Bersier, D.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Godoy-Rivera, D.; Basu, U.; Shappee, B. J.; Prieto, J. L.; Dong, Subo; Chen, Ping; Brimacombe, J.

    2016-01-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new type Ia supernova in the galaxy NGC 3926 NED02.

  2. IMPROVING COSMOLOGICAL DISTANCE MEASUREMENTS USING TWIN TYPE IA SUPERNOVAE

    SciTech Connect

    Fakhouri, H. K.; Boone, K.; Aldering, G.; Aragon, C.; Bailey, S.; Fagrelius, P.; Antilogus, P.; Bongard, S.; Fleury, M.; Baltay, C.; Barbary, K.; Baugh, D.; Chen, J.; Buton, C.; Chotard, N.; Copin, Y.; Feindt, U.; Fouchez, D. [Centre de Physique des Particules de Marseille, Aix-Marseille Université, CNRS Gangler, E. [Clermont Université, Université Blaise Pascal, CNRS Collaboration: Nearby Supernova Factory; and others

    2015-12-10

    We introduce a method for identifying “twin” Type Ia supernovae (SNe Ia) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083 ± 0.012 mag, implying a dispersion of 0.072 ± 0.010 mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric data set as a reference, this method will be capable of standardizing high-redshift SNe to within 0.06–0.07 mag. These results imply that at least 3/4 of the variance in Hubble residuals in current SN cosmology analyses is due to previously unaccounted-for astrophysical differences among the SNe.

  3. Constraining Type Ia Supernova Physics with Near-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sand, David; Valenti, Stefano; Howell, Andy; Graham, Melissa; Parrent, Jerod

    2014-02-01

    Despite their success as standardizable candles, relatively little is known about the exact progenitor(s) and explosion physics of type Ia supernovae -- a potential source of systematic uncertainty for future dark energy surveys, and a hole in our knowledge about stellar end-states. One promising route forward is the combination of dense optical time series and near-infrared (NIR) spectroscopic data sets. Recent work has suggested that the NIR can discern unburned carbon from the progenitor white dwarf more cleanly than in the optical, and its unique access to relatively unblended magnesium lines also probes the inner edge of carbon burning. Both measures provide a direct constraint for SN Ia explosion models, but only a handful of appropriate NIR spectroscopic time series exist. We propose to continue our campaign to roughly double the sample of SN Ia with such data (leveraging our access to a worldwide network of 1m imaging telescopes and twin robotic optical spectrographs) in order to begin to tackle our understanding of NIR spectral diagnostics and how they vary from supernova to supernova. Note that we were allocated time with Gemini South Flamingos-2 in 2013B, but have not triggered any ToO time yet, partially due to the persistent alignment issues with the On-Instrument Wave Front Sensor.

  4. Spectral classification of Gaia16amf as Type Ia SN

    NASA Astrophysics Data System (ADS)

    Piascik, A. S.; Steele, I. A.

    2016-05-01

    We conducted a spectroscopic observation of transient Gaia16amf at 2016-05-06T04:52:48 UT. This transient was observed by the Gaia Photometric Science survey on 2016-05-01T16:23:13 UT at position RA = 22:23:48.10, DEC = 41:33:45.30 A spectrum was obtained in the visible, 400-800nm, with resolution R~350, using the SPRAT spectrograph on the Liverpool Telescope located at Roque de los Muchachos.

  5. ASASSN-16hh Is a Type Ia SN Near Maximum

    NASA Astrophysics Data System (ADS)

    Bersier, D.

    2016-07-01

    We obtained a spectrum of the candidate supernova ASASSN-16hh/AT 2016daj (ATel #9254) with the SPRAT spectrograph mounted on the robotic 2m Liverpool Telescope at the Roque de los Muchachos observatory (La Palma).

  6. ASASSN-16hr Is a Type Ia SN Before Maximum

    NASA Astrophysics Data System (ADS)

    Bersier, D.

    2016-07-01

    We obtained a spectrum of the candidate supernova ASASSN-16hr/AT 2016eja (ATel #9270) with the SPRAT spectrograph mounted on the robotic 2m Liverpool Telescope at the Roque de los Muchachos observatory (La Palma).

  7. Grouping normal type Ia supernovae by UV to optical color differences

    SciTech Connect

    Milne, Peter A.; Brown, Peter J.; Roming, Peter W. A.; Bufano, Filomena; Gehrels, Neil

    2013-12-10

    Observations of many Type Ia supernovae (SNe Ia) for multiple epochs per object with the Swift Ultraviolet Optical Telescope instrument have revealed that there exists order to the differences in the UV-optical colors of optically normal supernovae (SNe). We examine UV-optical color curves for 23 SNe Ia, dividing the SNe into four groups, and find that roughly one-third of 'NUV-blue' SNe Ia have bluer UV-optical colors than the larger 'NUV-red' group. Two minor groups are recognized, 'MUV-blue' and 'irregular' SNe Ia. While we conclude that the latter group is a subset of the NUV-red group, containing the SNe with the broadest optical peaks, we conclude that the 'MUV-blue' group is a distinct group. Separating into the groups and accounting for the time evolution of the UV-optical colors lowers the scatter in two NUV-optical colors (e.g., u – v and uvw1 – v) to the level of the scatter in b – v. This finding is promising for extending the cosmological utilization of SNe Ia into the NUV. We generate spectrophotometry of 33 SNe Ia and determine the correct grouping for each. We argue that there is a fundamental spectral difference in the 2900-3500 Å wavelength range, a region suggested to be dominated by absorption from iron-peak elements. The NUV-blue SNe Ia feature less absorption than the NUV-red SNe Ia. We show that all NUV-blue SNe Ia in this sample also show evidence of unburned carbon in optical spectra, whereas only one NUV-red SN Ia features that absorption line. Every NUV-blue event also exhibits a low gradient of the Si II λ6355 absorption feature. Many NUV-red events also exhibit a low gradient, perhaps suggestive that NUV-blue events are a subset of the larger low-velocity gradient group.

  8. TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND INTERSTELLAR DUST

    NASA Astrophysics Data System (ADS)

    Huang, Xiaosheng; Biederman, M.; Herger, B.; Aldering, G. S.

    2014-01-01

    TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND NON-UNIFORM INTERSTELLAR DUST ABSTRACT We investigate the time variation of the visual extinction, AV, and the total-to-selective extinction ratio, RV, resulting from interstellar dust in front of an expanding photospheric disk of a type Ia supernova (SN Ia). We simulate interstellar dust clouds according to a power law power spectrum and produce extinction maps that either follow a pseudo-Gaussian distribution or a lognormal distribution. The RV maps are produced through a correlation between AV and RV. With maps of AV and RV generated in each case (pseudo-Gaussian and lognormal), we then compute the effective AV and RV for a SN as its photospheric disk expands behind the dust screen. We find for a small percentage of SNe the AV and RV values can vary by a large factor from day to day in the first 40 days after explosion.

  9. Three-dimensional pure deflagration models with nucleosynthesis and synthetic observables for Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Fink, Michael; Kromer, Markus; Seitenzahl, Ivo R.; Ciaraldi-Schoolmann, Franco; Röpke, Friedrich K.; Sim, Stuart A.; Pakmor, Rüdiger; Ruiter, Ashley J.; Hillebrandt, Wolfgang

    2014-02-01

    We investigate whether pure deflagration models of Chandrasekhar-mass carbon-oxygen white dwarf stars can account for one or more subclass of the observed population of Type Ia supernova (SN Ia) explosions. We compute a set of 3D full-star hydrodynamic explosion models, in which the deflagration strength is parametrized using the multispot ignition approach. For each model, we calculate detailed nucleosynthesis yields in a post-processing step with a 384 nuclide nuclear network. We also compute synthetic observables with our 3D Monte Carlo radiative transfer code for comparison with observations. For weak and intermediate deflagration strengths (energy release Enuc ≲ 1.1 × 1051 erg), we find that the explosion leaves behind a bound remnant enriched with 3 to 10 per cent (by mass) of deflagration ashes. However, we do not obtain the large kick velocities recently reported in the literature. We find that weak deflagrations with Enuc ˜ 0.5 × 1051 erg fit well both the light curves and spectra of 2002cx-like SNe Ia, and models with even lower explosion energies could explain some of the fainter members of this subclass. By comparing our synthetic observables with the properties of SNe Ia, we can exclude the brightest, most vigorously ignited models as candidates for any observed class of SN Ia: their B - V colours deviate significantly from both normal and 2002cx-like SNe Ia and they are too bright to be candidates for other subclasses.

  10. SNLS spectroscopy: testing for evolution in type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Hook, I. M.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Howell, D. A.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Sullivan, M.; Baumont, S.; Fabbro, S.; Filliol, M.; Perlmutter, S.; Ripoche, P.

    2008-01-01

    Aims:We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these distant SNe comprise a population similar to those observed locally. Methods: Rest-frame equivalent width and ejection velocity measurements are made on four spectroscopic features. Corresponding measurements are presented for a set of 167 spectra from 24 low-z SNe Ia from the literature. Results: We show that there exists a sample at high redshift with properties similar to nearby SNe. The high-z measurements are consistent with the range of measurements at low-z and no significant difference was found between the distributions of measurements at low and high redsift for three of the features. The fourth feature displays a possible difference that should be investigated further. Correlations between Type Ia SNe properties and host galaxy morphology were also found to be similar at low and high z, and within each host galaxy class we see no evidence for redshift-evolution in SN properties. A new correlation between SNe Ia peak magnitude and the equivalent width of SiII absorption is presented. Tests on a sub-set of the SNLS SNe demonstrates that this correlation reduces the scatter in SNe Ia luminosity distances in a manner consistent with the lightcurve shape-luminosity corrections that are used for Type Ia SNe cosmology. Conclusions: We show that this new sample of SNLS SNe Ia has spectroscopic properties similar to nearby objects. Tables 6, Appendices A and B are are only available in electronic

  11. Integrated Avionics System (IAS)

    NASA Technical Reports Server (NTRS)

    Hunter, D. J.

    2001-01-01

    As spacecraft designs converge toward miniaturization and with the volumetric and mass constraints placed on avionics, programs will continue to advance the 'state of the art' in spacecraft systems development with new challenges to reduce power, mass, and volume. Although new technologies have improved packaging densities, a total system packaging architecture is required that not only reduces spacecraft volume and mass budgets, but increase integration efficiencies, provide modularity and scalability to accommodate multiple missions. With these challenges in mind, a novel packaging approach incorporates solutions that provide broader environmental applications, more flexible system interconnectivity, scalability, and simplified assembly test and integration schemes. This paper will describe the fundamental elements of the Integrated Avionics System (IAS), Horizontally Mounted Cube (HMC) hardware design, system and environmental test results. Additional information is contained in the original extended abstract.

  12. CfA4: LIGHT CURVES FOR 94 TYPE Ia SUPERNOVAE

    SciTech Connect

    Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Bakos, Gaspar; Berlind, Perry; Brown, Warren R.; Caldwell, Nelson; Calkins, Mike; Falco, Emilio; Fernandez, Jose; Friedman, Andrew S.; Groner, Ted; Hartman, Joel; Rest, Armin; Cramer, Claire E.; Wood-Vasey, W. Michael; Currie, Thayne; De Kleer, Kathy; Esquerdo, Gil; Everett, Mark; and others

    2012-06-01

    We present multi-band optical photometry of 94 spectroscopically confirmed Type Ia supernovae (SNe Ia) in the redshift range 0.0055-0.073, obtained between 2006 and 2011. There are a total of 5522 light-curve points. We show that our natural-system SN photometry has a precision of {approx}< 0.03 mag in BVr'i', {approx}< 0.06 mag in u', and {approx}< 0.07 mag in U for points brighter than 17.5 mag and estimate that it has a systematic uncertainty of 0.014, 0.010, 0.012, 0.014, 0.046, and 0.073 mag in BVr'i'u'U, respectively. Comparisons of our standard-system photometry with published SN Ia light curves and comparison stars reveal mean agreement across samples in the range of {approx}0.00-0.03 mag. We discuss the recent measurements of our telescope-plus-detector throughput by direct monochromatic illumination by Cramer et al. This technique measures the whole optical path through the telescope, auxiliary optics, filters, and detector under the same conditions used to make SN measurements. Extremely well characterized natural-system passbands (both in wavelength and over time) are crucial for the next generation of SN Ia photometry to reach the 0.01 mag accuracy level. The current sample of low-z SNe Ia is now sufficiently large to remove most of the statistical sampling error from the dark-energy error budget. But pursuing the dark-energy systematic errors by determining highly accurate detector passbands, combining optical and near-infrared (NIR) photometry and spectra, using the nearby sample to illuminate the population properties of SNe Ia, and measuring the local departures from the Hubble flow will benefit from larger, carefully measured nearby samples.

  13. The Physics of White Dwarf Mergers and Detonations: A Path to Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Chang, Philip

    This project will investigate the double degenerate scenario for Type Ia supernova (SN Ia) and the physics of detonation initiation in white dwarfs. While the progenitors of SN Ia are not known, the detonation of a remnant from a pair of merging white dwarfs produces a mix of burnt material that is similar to the compositional makeup of SN Ia. Hence, the merger of two white dwarfs and detonation of its relaxed remnant is a promising avenue to SN Ia. Using a combination of numerical and analytic techniques, the PI and his collaborators will investigate the merger of two white dwarfs and the initiation of detonations in these remnants. In particular, the group will use a previously modified smooth particle hydrodynamics code to perform a parameter study of the mergers of two white dwarfs. The group will then determine how the properties of the resulting remnant depends on it initial conditions of the merger. In doing so, the group will map out the parameter space of white dwarf mergers, whose remnant's secular evolution that can lead to Type Ia supernova. The group will also investigate the physics of detonation initiation in WDs. In particular, the group will leverage prior work on terrestial detonations to map the controlling parameters of detonation initiation in WDs. For instance, the group will determine the physics of detonations for a given size and shape of a hotspot, i.e., if the detonation occurs due pure combustion effects or if the interaction between combustion waves and hydrodynamics waves are important. Armed with this information, the group will proceed to study if large scale turbulence can give rise the hotspots capable of initiating detonations and the physics of these initiations. The work performed by this group will be important in future dark energy survey mission such as a WFIRST descendent and in current transient all-sky surveys.

  14. Visible and Near-infrared Light Curves of SN 2009nr

    NASA Astrophysics Data System (ADS)

    Heath, Jonathan; Bryngelson, Ginger

    2014-03-01

    This study explores the behavior of SN 2009nr, an apparently normal type Ia supernova (SN Ia). A plot of this object's brightness over time is known as a light curve. Because of the uniformity of their light curves, SNe Ia are valuable markers for determining the expansion of the universe and other cosmological parameters. Understanding the properties of these supernovae is vital in order to build our confidence in their use as standard candles. A small, but increasing number of SN Ia late-time observations have been made in the near-infrared (NIR). Most exhibit a flattening of the NIR power even as the visible light declines at a steady rate. It is still unclear as to why they exhibit this behavior and how typical this is. In order to characterize the late behavior of SNe Ia, images of SN 2009nr were analyzed using the Image Reduction and Analysis Facility (IRAF). NIR (J, H, K) images were taken with the 4m Mayall Telescope at Kitt Peak National-Observatory using the FLAMINGOS IR Imaging Spectrometer while visible (B, V, R, I) images used the Mosaic 1 imager. The supernova's apparent magnitude for each night of observation (by filter) was found by using reference stars. We present preliminary light curves of SN 2009nr and a comparison to another SN observed at similar epochs.

  15. Detectability of Cosmic Dark Flow in the Type Ia Supernova Redshift‒Distance Relation

    NASA Astrophysics Data System (ADS)

    Mathews, G. J.; Rose, B. M.; Garnavich, P. M.; Yamazaki, D. G.; Kajino, T.

    2016-08-01

    We reanalyze the detectability of large-scale dark flow (or local bulk flow) with respect to the CMB background based upon the redshift-distance relation for SN Ia. We made two independent analyses: one based upon identifying the three Cartesian velocity components; and the other based upon the cosine dependence of the deviation from Hubble flow on the sky. We apply these analyses to the Union2.1 SN Ia data and to the SDSS-II supernova survey. For both methods, results for low redshift, z\\lt 0.05, are consistent with previous searches. We find a local bulk flow of v bf ˜ 300 km s-1 in the direction of (l, b) ˜ (270, 35)°. However, the search for a dark flow at z\\gt 0.05 is inconclusive. Based upon simulated data sets, we deduce that the difficulty in detecting a dark flow at high redshifts arises mostly from the observational error in the distance modulus. Thus, even if it exists, a dark flow is not detectable at large redshift with current SN Ia data sets. We estimate that a detection would require both significant sky coverage of SN Ia out to z = 0.3 and a reduction in the effective distance modulus error from 0.2 mag to ≲0.02 mag. We estimate that a greatly expanded data sample of ˜104 SN Ia might detect a dark flow as small as 300 km s-1 out to z = 0.3 even with a distance modulus error of 0.2 mag. This may be achievable in a next generation large survey like LSST.

  16. Could there be a hole in type Ia supernovae?

    SciTech Connect

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-04-23

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

  17. Light Echoes as Probes of Supernova Type Ia Environments

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2009-07-01

    Environmental factors of Type Ia supernovae are key in understanding their nature, lightcurve evolution, and utility as cosmological standard candles. The progenitor ages {and many other properties} are bimodal, differing by roughly an order of magnitude. Is this reflected as well in the differences in their immediate surroundings in terms of gas and dust? The most powerful and direct way to address this issue is by imaging the reflected light from the dust itself via a light echo. In order for this approach to work, however, one must start imaging the vicinity of the supernova frequently and soon after the explosion is seen. We propose to maintain the imaging sequences crucial for understanding the three-dimensional dust distribution of two recent and key Type Ia supernovae, in a timely manner that will prevent otherwise significant holes in our knowledge. These observations are likely to be important in determining if the interstellar versus the circumstellar environments are more important in determining the appearance of Type Ia explosions, and thereby offer a clue as to the poorly-understood mass-loss history of SN Ia progenitors.JUSTIFICATION FOR VISIT TIME CONSTRAINTS:We have requested "Before" conditions

  18. Analytic photometric redshift estimator for Type Ia supernovae from the Large Synoptic Survey Telescope

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Gjergo, E.; Kuhlmann, S.

    2015-08-01

    Accurate and precise photometric redshifts (photo-zs) of Type Ia supernovae (SNe Ia) can enable the use of SNe Ia, measured only with photometry, to probe cosmology. This dramatically increases the science return of supernova surveys planned for the Large Synoptic Survey Telescope (LSST). In this paper we describe a significantly improved version of the simple analytic photo-z estimator proposed by Wang and further developed by Wang, Narayan & Wood-Vasey. We apply it to 55 422 simulated SNe Ia generated using the SNANA package with the LSST filters. We find that the estimated errors on the photo-zs, σ _{z_phot}/(1+z_phot), can be used as filters to produce a set of photo-zs that have high precision, accuracy, and purity. Using SN Ia colours as well as SN Ia peak magnitude in the i band, we obtain a set of photo-zs with 2 per cent accuracy (with σ(zphot - zspec)/(1 + zspec) = 0.02), a bias in zphot (the mean of zphot - zspec) of -9 × 10-5, and an outlier fraction (with |(zphot - zspec)/(1 + zspec)| > 0.1) of 0.23 per cent, with the requirement that σ _{z_phot}/(1+z_phot)<0.01. Using the SN Ia colours only, we obtain a set of photo-zs with similar quality by requiring that σ _{z_phot}/(1+z_phot)<0.007; this leads to a set of photo-zs with 2 per cent accuracy, a bias in zphot of 5.9 × 10-4, and an outlier fraction of 0.32 per cent.

  19. Spectroscopic identification of SNe 2004ds and SN 2004dt

    NASA Astrophysics Data System (ADS)

    Gal-Yam, Avishay

    2004-08-01

    A. Gal-Yam, D. Fox and S. Kulkarni, California Institute of Technology, report on red spectra (range 550-780 nm) obtained by Kulkarni and Fox on Aug. 13.5 UT at the 10-m Keck I telescope (+ LRIS). The spectrum of of SN 2004ds (IAUC #8386), shows a broad, well-developed P-Cyg H_alpha line and suggests that this is a type II supernova. The spectrum of SN 2004dt (IAUC #8386), shows the distinctive Si II 6100 absorption trough around 6100 Angstrom, indicating this is a young SN Ia.

  20. Discovery of 90 Type Ia supernovae among 700 000 Sloan spectra: the Type Ia supernova rate versus galaxy mass and star formation rate at redshift ˜0.1

    NASA Astrophysics Data System (ADS)

    Graur, Or; Maoz, Dan

    2013-04-01

    Using a method to discover and classify supernovae (SNe) in galaxy spectra, we find 90 Type Ia SNe (SNe Ia) and 10 Type II SNe among the ˜700 000 galaxy spectra in the Sloan Digital Sky Survey Data Release 7 that have star-formation histories (SFHs) derived with the VErsatile SPectral Analysis code (VESPA). We use the SN Ia sample to measure SN Ia rates per unit stellar mass. We confirm, at the median redshift of the sample, z = 0.1, the inverse dependence on galaxy mass of the SN Ia rate per unit mass, previously reported by Li et al. for a local sample. We further confirm, following Kistler et al., that this relation can be explained by the combination of galaxy `downsizing' and a power-law delay-time distribution (DTD; the distribution of times that elapse between a hypothetical burst of star formation and the subsequent SN Ia explosions) with an index of -1, inherent to the double-degenerate progenitor scenario. We use the method of Maoz et al. to recover the DTD by comparing the number of SNe Ia hosted by each galaxy in our sample with the VESPA-derived SFH of the stellar population within the spectral aperture. In this galaxy sample, which is dominated by old and massive galaxies, we recover a `delayed' component to the DTD of 4.5 ± 0.6 (statistical){_{-0.5}^+0.3} (systematic) × 10- 14 SNe M⊙- 1 yr- 1 for delays in the range >2.4 Gyr. The mass-normalized SN Ia rate, averaged over all masses and redshifts in our galaxy sample, is R_{Ia,M}(z=0.1) = 0.10 ± 0.01 (statistical) ± 0.01 (systematic) SNuM, and the volumetric rate is RIa, V(z = 0.1) = 0.247_{-0.026}^{+0.029} (statistical) _{-0.031}^{+0.016} (systematic) × 10- 4 SNe yr- 1 Mpc- 3. This rate is consistent with the rates and rate evolution from other recent SN Ia surveys, which together also indicate a ˜t-1 DTD.

  1. Rotation of surviving companion stars after type Ia supernova explosions in the WD+MS scenario

    NASA Astrophysics Data System (ADS)

    Liu, Z.-W.; Pakmor, R.; Röpke, F. K.; Edelmann, P.; Hillebrandt, W.; Kerzendorf, W. E.; Wang, B.; Han, Z. W.

    2013-06-01

    Context. In the single-degenerate (SD) scenario of type Ia supernovae (SNe Ia) the non-degenerate companion star survives the supernova (SN) explosion and thus should be visible near the center of the SN remnant and may show some unusual features. Therefore, a promising approach to test progenitor models of SNe Ia is to search for the companion star in historical SN remnants. Aims: Here we present the results of three-dimensional (3D) hydrodynamics simulations of the interaction between the SN Ia blast wave and a main-sequence companion taking into consideration its orbital motion and spin. The primary goal of this work is to investigate the rotation of surviving companion stars after SN Ia explosions in the WD+MS scenario. Methods: We used Eggleton's stellar evolution code including the optically thick accretion wind model to obtain realistic models of companion stars. The impact of the supernova blast wave on these companion stars was followed in 3D hydrodynamic simulations employing the smoothed particle hydrodynamics (SPH) code GADGET3. Results: We find that the rotation of the companion star does not significantly affect the amount of stripped mass and the kick velocity caused by the SN impact. However, in our simulations, the rotational velocity of the companion star is significantly reduced to about 14% to 32% of its pre-explosion value due to the expansion of the companion and because 55%-89% of the initial angular momentum is carried away by the stripped matter. Conclusions: Compared with the observed rotational velocity of the presumed companion star of Tycho's supernova, Tycho G, of ~6 km s-1, the final rotational velocity we obtain in our simulations is still higher by at least a factor of two. Whether this difference is significant and may cast doubts on the suggestion that Tycho G is the companion of SN 1572 has to be investigated in future studies. Based on binary population synthesis results, we present for the first time the expected distribution

  2. Early-time observations of Type Ia supernovae to reveal progenitor material

    NASA Astrophysics Data System (ADS)

    Howell, D. Andrew; Parrent, Jerod; Sullivan, Mark; Maguire, Kate; Nugent, Peter; Dilday, Benjamin; Graham, Melissa

    2013-02-01

    SNe Ia remain nature's best standardized candles, and yet their progenitors have long been a mystery. However, it is now clear that there is a multiplicity of SN Ia progenitors. Recent findings that SNe Ia correct to different absolute magnitudes in different mass galaxies may be related to differing progenitors, and/or explosion physics. With this proposal we will obtrain early GMOS spectroscopy of SNe a few days after explosion with three main goals: (1) trigger our high resolution spectroscopy time on Keck HIRES and VLT X-Shooter to search for circumstellar material indicative of a single degenerate origin, (2) build the first well-controlled sample studying unburned progenitor carbon in SNe Ia, testing whether this traces white dwarf mergers or explosion physics (3) type SNe as early as possible to enable follow-up observations and studies, including cosmology. Our results depend on early-time observations for which the queue-scheduled Gemini is uniquely suited.

  3. Early-time observations of Type Ia supernovae to reveal progenitors and metallicity

    NASA Astrophysics Data System (ADS)

    Howell, D. Andrew; Sullivan, Mark; Maguire, Kate; Parrent, Jerod; Nugent, Peter; Ellis, Richard; Dilday, Benjamin; Graham, Melissa; Hook, Isobel

    2012-08-01

    SNe Ia remain nature's best standardized candles, and yet their progenitors have long been a mystery. However, it is now clear that there is a multiplicity of SN Ia progenitors. Recent findings that SNe Ia correct to different absolute magnitudes in different mass galaxies may be related to differing progenitors, and/or progenitor metallicity. With this proposal we will obtrain early GMOS spectroscopy of SNe a few days after explosion with three main goals: (1) to trigger our proposed HST Cycle 20 STIS observations probing early UV spectra and thus metallicity, (2) trigger our high resolution spectroscopy time on Keck HIRES and VLT X-shooter to search for circumstellar material indicative of a single degenerate origin, (3) build the first well-controlled sample studying unburned progenitor carbon in SNe Ia, testing whether this traces white dwarf mergers or explosion physics. Our results depend on early-time observations for which the queue-scheduled Gemini is uniquely suited.

  4. Type Ia supernova rate at a redshift of ~;0.1

    SciTech Connect

    Blanc, G.; Afonso, C.; Alard, C.; Albert, J.N.; Aldering, G.; Amadon, A.; Andersen, J.; Ansari, R.; Aubourg, E.; Balland, C.; Bareyre,P.; Beaulieu, J.P.; Charlot, X.; Conley, A.; Coutures, C.; Dahlen, T.; Derue, F.; Fan, X.; Ferlet, R.; Folatelli, G.; Fouque, P.; Garavini, G.; Glicenstein, J.F.; Goldman, B.; Goobar, A.; Gould, A.; Graff, D.; Gros,M.; Haissinski, J.; Hamadache, C.; Hardin, D.; Hook, I.M.; deKat, J.; Kent, S.; Kim, A.; Lasserre, T.; LeGuillou, L.; Lesquoy, E.; Loup, C.; Magneville, C.; Marquette, J.B.; Maurice, E.; Maury, A.; Milsztajn, A.; Moniez, M.; Mouchet, M.; Newberg, H.; Nobili, S.; Palanque-Delabrouille,N.; Perdereau, O.; Prevot, L.; Rahal, Y.R.; Regnault, N.; Rich, J.; Ruiz-Lapuente, P.; Spiro, M.; Tisserand, P.; Vidal-Madjar, A.; Vigroux,L.; Walton, N.A.; Zylberajch, S.

    2004-05-11

    We present the type Ia rate measurement based on two EROS supernova search campaigns (in 1999 and 2000). Sixteen supernovae identified as type Ia were discovered. The measurement of the detection efficiency, using a Monte Carlo simulation, provides the type Ia supernova explosion rate at a redshift {approx} 0.13. The result is 0.125{sub -0.034-0.028}{sup +0.044+0.028} h{sub 70}{sup 2} SNu where 1 SNu = 1 SN/10{sup 10} L{sub {circle_dot}}{sup B}/century. This value is compatible with the previous EROS measurement (Hardin et al. 2000), done with a much smaller sample, at a similar redshift. Comparison with other values at different redshifts suggests an evolution of the type Ia supernova rate.

  5. [Congenital disorder of glycosylation type Ia (CDG Ia) - underdiagnosed entity?].

    PubMed

    Sätilä, Heli; Kuusela, Anna-Leena; Pietilä, Kati; Niinikoski, Harri; Keskinen, Päivi

    2016-01-01

    Congenital disorders of glycosylation (CDG) are a relatively recently identified group of multisystem disorders caused by defective glycosylation of N-glycosylated proteins. They mainly involve the central and peripheral nervous system, but other organ systems are involved as well. Type CDG Ia accounts for over 80% of cases, characterized by decreased activity of the enzyme phosphomannomutase caused by mutations in chromosome 16 PMM2 gene. Treatment of CDG Ia remains symptomatic.

  6. Radio Observations of SN 2008ha

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia

    2009-03-01

    I observed the peculiar SN 2008ha (CBET #1567) with the Very Large Array on 2008 Nov 21.99 UT at a frequency of 8.46 GHz. No radio source is detected at the optical SN position to a limit of 93 microJy (3 sigma). At a distance of 21 Mpc, this corresponds to a radio luminosity limit similar to those of nearby Type Ia supernovae (Panagia et al. 2006). It is also consistent with the observed radio luminosities for the nearest Type Ibc supernovae (e.g., SN 2002ap; Berger, Kulkarni & Chevalier 2002), but a factor of 10^3 and 10^5 below the radio luminosities of sub-energetic GRBs (Soderberg et al.

  7. EVOLUTION OF POST-IMPACT REMNANT HELIUM STARS IN TYPE Ia SUPERNOVA REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu

    2013-08-10

    The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova (SN) impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase (L {approx} 10{sup 4} L{sub Sun }) about 10 yr after an SN explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that a luminous OB-like star should be detectable within {approx}30 yr after the SN explosion. Thereafter, it will shrink and become an sdO-like star in the central regions of SN Ia remnants within star-forming regions for SN Ia progenitors evolved via the helium-star channel in the SDS. These He PIRSs are predicted to be rapidly rotating (v{sub rot} {approx}> 50 km s{sup -1}) and to have high spatial velocities (v{sub linear} {approx}> 500 km s{sup -1}). Furthermore, if SN remnants have diffused away and are not recognizable at a later stage, He PIRSs could be an additional source of single sdO stars and/or hypervelocity stars.

  8. FORMATION OF DUST IN THE EJECTA OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Nozawa, Takaya; Maeda, Keiichi; Tanaka, Masaomi; Nomoto, Ken'ichi; Kozasa, Takashi; Umeda, Hideyuki

    2011-07-20

    We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two extreme cases of the formation of CO and SiO molecules: complete formation and no formation. The results of the calculations show that for the sticking probability of {alpha}{sub j} = 1, C, silicate, Si, and FeS grains can condense at early times of {approx}100-300 days after the explosion, whereas Fe and SiC grains cannot form substantially. Due to the low gas density in SNe Ia with no H-envelope, the average radii of the newly formed grains are generally below 0.01 {mu}m, being much smaller than those in Type II-P SNe. This supports our previous conclusion that the radius of dust formed in the ejecta is smaller in SNe with less massive envelopes. The total dust mass ranges from 3 x 10{sup -4} M{sub sun} to 0.2 M{sub sun} for {alpha}{sub j} = 0.1-1, depending on whether or not CO and SiO molecules are formed. We also estimate the optical depths and thermal emission by the newly formed dust and compare them to the relevant observations of SNe Ia. We find that the formation of C grains in SNe Ia must be suppressed to be consistent with observational constraints. This implies that energetic photons and electrons heavily depress the formation efficiency of C grains or that the outermost C-O layer of SNe Ia is almost fully burned. Finally, we calculate dust destruction in the SN remnants and find that dust grains formed in the ejecta of SNe Ia are almost completely destroyed in the shocked gas before being injected into the interstellar medium. This indicates that SNe Ia are unlikely to be the major sources of interstellar dust.

  9. Standardization of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Coelho, Rodrigo C. V.; Calvão, Maurício O.; Reis, Ribamar R. R.; Siffert, Beatriz B.

    2015-01-01

    Type Ia supernovae (SNe Ia) have been intensively investigated due to their great homogeneity and high luminosity, which make it possible to use them as standardizable candles for the determination of cosmological parameters. In 2011, the physics Nobel prize was awarded ‘for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.’ This is a pedagogical article, aimed at those starting their study of that subject, in which we dwell on some topics related to the analysis of SNe Ia and their use in luminosity distance estimators. Here, we investigate their spectral properties and light curve standardization, paying careful attention to the fundamental quantities directly related to the SNe Ia observables. Finally, we describe our own step-by-step implementation of a classical light curve fitter, the stretch, applying it to real data from the Carnegie Supernova Project.

  10. Survey for the Binary Progenitor in SN1006 and Update on SN1572

    NASA Astrophysics Data System (ADS)

    Ruiz-Lapuente, Pilar; Hernández, Jonay González; Tabernero, Hugo; Montes, David; Canal, Ramon; Mendez, Javier; Bedin, Luigi

    2013-01-01

    We have completed a survey down to R = 15 mag of the stars within a circle of 4 arcmin radius around the nominal center of the remnant of SN 1006, one of the three historical Type Ia supernovae (the other two being SN 1572 and SN 1604), in search of a possible surviving binary companion of the white dwarf whose explosion gave rise to the supernova. The stellar parameters (effective temperature, surface gravity, and metallicity), as well as the radial velocities of all the stars, have been measured from spectra obtained with the UVES spectrograph at the VLT, and from the former and the available photometry, distances have been determined. Chemical abundances of the Fe-peak elements Cr, Mn, Co, and Ni have also been measured to check for possible contamination of the stellar surface by the supernova ejecta. The limiting magnitude of the survey would allow us to find stellar companions of the red-giant type, subgiant stars, and main-sequence stars down to F5-6. Unlike in SN 1572, where a subgiant of type G0-1 has been proposed as the companion of SN 1572, for SN 1006 we can discard the possibility that SN 1006 had a red giant or subgiant companion.

  11. Supernova SN 2012dn: a spectroscopic clone of SN 2006gz

    NASA Astrophysics Data System (ADS)

    Chakradhari, N. K.; Sahu, D. K.; Srivastav, S.; Anupama, G. C.

    2014-09-01

    We present optical and UV analysis of the luminous Type Ia supernova SN 2012dn covering the period from ˜-11 to +109 d with respect to the B-band maximum, which occurred on JD 245 6132.89 ± 0.19, with an apparent magnitude of mB^max = 14.38 ± 0.02. The absolute magnitudes at maximum in B and V bands are MB^max = -19.52 ± 0.15 and MV^max = -19.42 ± 0.15, respectively. SN 2012dn is marginally luminous compared to normal Type Ia supernovae. The peak bolometric luminosity of log L_bol^max = 43.27 ± 0.06 erg s-1 suggests that 0.82 ± 0.12 M⊙ of 56Ni was synthesized in the explosion. The decline rate Δm15(B)true = 0.92 ± 0.04 mag is lower than that of normal Type Ia supernovae, and similar to the luminous SN 1991T. However, the photometric and spectroscopic behaviour of SN 2012dn is different from that of SN 1991T. Early-phase light curves in R and I bands are very broad. The I-band peak has a plateau-like appearance similar to the super-Chandra SN 2009dc. Pre-maximum spectra show clear evidence of C II 6580 Å line, indicating the presence of unburned materials. The velocity evolution of C II line is peculiar. Except for the very early phase (˜-13 d), the C II line velocity is lower than the velocity estimated using the Si II line. During the pre-maximum and close to the maximum phase, to reproduce observed shape of the spectra, the synthetic spectrum code SYN++ needs significantly higher blackbody temperature than those required for normal Type Ia events. The photospheric velocity evolution and other spectral properties are similar to those of the carbon-rich SN 2006gz.

  12. Photometric selection of Type Ia supernovae in the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Bazin, G.; Ruhlmann-Kleider, V.; Palanque-Delabrouille, N.; Rich, J.; Aubourg, E.; Astier, P.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I. M.; Howell, D. A.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Sullivan, M.; Fourmanoit, N.; González-Gaitán, S.; Lidman, C.; Perlmutter, S.; Ripoche, P.; Walker, E. S.

    2011-10-01

    We present a sample of 485 photometrically identified Type Ia supernova candidates mined from the first three years of data of the CFHT SuperNova Legacy Survey (SNLS). The images were submitted to a deferred processing independent of the SNLS real-time detection pipeline. Light curves of all transient events were reconstructed in the gM, rM, iM and zM filters and submitted to automated sequential cuts in order to identify possible supernovae. Pure noise and long-term variable events were rejected by light curve shape criteria. Type Ia supernova identification relied on event characteristics fitted to their light curves assuming the events to be normal SNe Ia. The light curve fitter SALT2 was used for this purpose, assigning host galaxy photometric redshifts to the tested events. The selected sample of 485 candidates is one magnitude deeper than that allowed by the SNLS spectroscopic identification. The contamination by supernovae of other types is estimated to be 4%. Testing Hubble diagram residuals with this enlarged sample allows us to measure the Malmquist bias due to spectroscopic selections directly. The result is fully consistent with the precise Monte Carlo based estimate used to correct SN Ia distance moduli in the SNLS 3-year cosmological analyses. This paper demonstrates the feasibility of a photometric selection of high redshift supernovae with known host galaxy redshifts, opening interesting prospects for cosmological analyses from future large photometric SN Ia surveys.

  13. Type Ia supernova rate measurements to redshift 2.5 from CANDELS: Searching for prompt explosions in the early universe

    SciTech Connect

    Rodney, Steven A.; Riess, Adam G.; Graur, Or; Jones, David O.; Strolger, Louis-Gregory; Dahlen, Tomas; Casertano, Stefano; Ferguson, Henry C.; Koekemoer, Anton M.; Dickinson, Mark E.; Garnavich, Peter; Hayden, Brian; Jha, Saurabh W.; McCully, Curtis; Patel, Brandon; Kirshner, Robert P.; Mobasher, Bahram; Weiner, Benjamin J.; Cenko, S. Bradley; Clubb, Kelsey I.; and others

    2014-07-01

    The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ∼0.25 deg{sup 2} with ∼900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ∼ 2.5. We classify ∼24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ∼3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f{sub P} = 0.53{sub stat0.10}{sup ±0.09}{sub sys0.26}{sup ±0.10}, consistent with a delay time distribution that follows a simple t {sup –1} power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions—though further analysis and larger samples will be needed to examine that suggestion.

  14. VizieR Online Data Catalog: YJK for Type Ia supernovae (Dhawan+, 2015)

    NASA Astrophysics Data System (ADS)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Maguire, K.

    2015-09-01

    We investigate a large sample of nearby objects with well-sampled optical and NIR data (Table 1). The main data source of NIR SN Ia photometry is the Carnegie SN Project (CSP; Contreras et al., 2010, Cat. J/AJ/139/519; Burns et al. 2011AJ....141...19B, 2014ApJ...789...32B; Stritzinger et al., 2011, Cat. J/AJ/142/156; Phillips, 2012PASA...29..434P). The low-redshift CSP provides a sample of SNe Ia with optical and NIR light curves in a homogeneous and well-defined photometric system ( in Vega magnitude system) and thus forms an ideal basis for the evaluation of light-curve properties. CSP relies primarily on SN discoveries from the Lick Observatory SN Search (Leaman et al., 2011, Cat. J/MNRAS/412/1419). The CSP has published light curves on a total of 82 SNe Ia of which 70 have photometry in YJHK bands. (6 data files).

  15. The Rise Time of Normal and Subluminous Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    González-Gaitán, S.; Conley, A.; Bianco, F. B.; Howell, D. A.; Sullivan, M.; Perrett, K.; Carlberg, R.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Fouchez, D.; Fourmanoit, N.; Graham, M. L.; Guy, J.; Hardin, D.; Hook, I. M.; Lidman, C.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Ruhlmann-Kleider, V.

    2012-01-01

    We calculate the average stretch-corrected rise time of Type Ia supernovae (SNe Ia) in the Supernova Legacy Survey. We use the aggregate light curves of spectroscopic and photometrically identified SNe Ia to fit the rising part of the light curve with a simple quadratic model. We obtain a light curve shape corrected, i.e., stretch-corrected, fiducial rise time of 17.02+0.18 - 0.28 (stat) days. The measured rise time differs from an earlier finding by the SNLS (Conley et al.) due to the use of different SN Ia templates. We compare it to nearby samples using the same methods and find no evolution in the early part of the light curve of SNe Ia up to z = 1. We search for variations among different populations, particularly subluminous objects, by dividing the sample in stretch. Bright and slow decliners (s > 1.0) have consistent stretch-corrected rise times compared to fainter and faster decliners (0.8 < s <= 1.0); they are shorter by 0.57+0.47 - 0.50 (stat) days. Subluminous SNe Ia (here defined as objects with s <= 0.8), although less constrained, are also consistent, with a rise time of 18.03+0.81 - 1.37 (stat) days. We study several systematic biases and find that the use of different fiducial templates may affect the average rise time but not the intrinsic differences between populations. Based on our results, we estimate that subluminous SNe Ia are powered by 0.05-0.35 M ⊙ of 56Ni synthesized in the explosion. Our conclusions are the same for the single-stretch and two-stretch parameterizations of the light curve. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products at the Canadian Astronomy Data Centre as part of the Canada

  16. Gamma-ray diagnostics of Type Ia supernovae. Predictions of observables from three-dimensional modeling

    NASA Astrophysics Data System (ADS)

    Summa, A.; Ulyanov, A.; Kromer, M.; Boyer, S.; Röpke, F. K.; Sim, S. A.; Seitenzahl, I. R.; Fink, M.; Mannheim, K.; Pakmor, R.; Ciaraldi-Schoolmann, F.; Diehl, R.; Maeda, K.; Hillebrandt, W.

    2013-06-01

    Context. Although the question of progenitor systems and detailed explosion mechanisms still remains a matter of discussion, it is commonly believed that Type Ia supernovae (SNe Ia) are production sites of large amounts of radioactive nuclei. Even though the gamma-ray emission due to radioactive decays is responsible for powering the light curves of SNe Ia, gamma rays themselves are of particular interest as a diagnostic tool because they directly lead to deeper insight into the nucleosynthesis and the kinematics of these explosion events. Aims: We study the evolution of gamma-ray line and continuum emission of SNe Ia with the objective of analyzing the relevance of observations in this energy range. We seek to investigate the chances for the success of future MeV missions regarding their capabilities for constraining the intrinsic properties and the physical processes of SNe Ia. Methods: Focusing on two of the most broadly discussed SN Ia progenitor scenarios - a delayed detonation in a Chandrasekhar-mass white dwarf (WD) and a violent merger of two WDs - we used three-dimensional explosion models and performed radiative transfer simulations to obtain synthetic gamma-ray spectra. Both chosen models produce the same mass of 56Ni and have similar optical properties that are in reasonable agreement with the recently observed supernova SN 2011fe. We examine the gamma-ray spectra with respect to their distinct features and draw connections to certain characteristics of the explosion models. Applying diagnostics, such as line and hardness ratios, the detection prospects for future gamma-ray missions with higher sensitivities in the MeV energy range are discussed. Results: In contrast to the optical regime, the gamma-ray emission of our two chosen models proves to be quite different. The almost direct connection of the emission of gamma rays to fundamental physical processes occurring in SNe Ia permits additional constraints concerning several explosion model properties

  17. Signatures of a companion star in type Ia supernovae

    SciTech Connect

    Maeda, Keiichi; Kutsuna, Masamichi; Shigeyama, Toshikazu

    2014-10-10

    Although type Ia supernovae (SNe Ia) have been used as precise cosmological distance indicators, their progenitor systems remain unresolved. One of the key questions is whether there is a nondegenerate companion star at the time of a thermonuclear explosion of a white dwarf. In this paper, we investigate whether an interaction between the SN ejecta and the companion star may result in observable footprints around the maximum brightness and thereafter, by performing multidimensional radiation transfer simulations based on hydrodynamic simulations of the interaction. We find that such systems result in variations in various observational characteristics due to different viewing directions, and the predicted behaviors (redder and fainter for the companion direction) are the opposite of what were suggested by the previous study. The variations are generally modest and within observed scatters. However, the model predicts trends between some observables different from those observationally derived, so a large sample of SNe Ia with small calibration errors may be used to constrain the existence of such a companion star. The variations in different colors in optical band passes can be mimicked by external extinctions, so such an effect could be a source of scatter in the peak luminosity and derived distance. After the peak, hydrogen-rich materials expelled from the companion will manifest themselves in hydrogen lines, but Hα is extremely difficult to identify. Alternatively, we find that P{sub β} in postmaximum near-infrared spectra can potentially provide a powerful diagnostic.

  18. Dust around Type Ia supernovae

    SciTech Connect

    Wang, Lifan

    2005-10-20

    An explanation is given of the low value of R lambda triple bond A lambda/E(B - V), the ratio of absolute to selective extinction deduced from Type Ia supernova observations. The idea involves scattering by dust clouds located in the circumstellar environment, or at the highest velocity shells of the supernova ejecta. The scattered light tends to reduce the effective R lambda in the optical, but has an opposite effect in the ultraviolet. The presence of circumstellar dust can be tested by ultraviolet to near infrared observations and by multi-epoch spectropolarimetry of SNe Ia.

  19. The early spectral evolution of SN 2004dt

    NASA Astrophysics Data System (ADS)

    Altavilla, G.; Stehle, M.; Ruiz-Lapuente, P.; Mazzali, P.; Pignata, G.; Balastegui, A.; Benetti, S.; Blanc, G.; Canal, R.; Elias-Rosa, N.; Goobar, A.; Harutyunyan, A.; Pastorello, A.; Patat, F.; Rich, J.; Salvo, M.; Schmidt, B. P.; Stanishev, V.; Taubenberger, S.; Turatto, M.; Hillebrandt, W.

    2007-11-01

    Aims:We study the optical spectroscopic properties of Type Ia Supernova (SN Ia) 2004dt, focusing our attention on the early epochs. Methods: Observation triggered soon after the SN 2004dt discovery allowed us to obtain a spectrophotometric coverage from day -10 to almost one year (~353 days) after the B band maximum. Observations carried out on an almost daily basis allowed us a good sampling of the fast spectroscopic evolution of SN 2004dt in the early stages. To obtain this result, low-resolution, long-slit spectroscopy was obtained using a number of facilities. Results: This supernova, which in some absorption lines of its early spectra showed the highest degree of polarization ever measured in any SN Ia, has a complex velocity structure in the outer layers of its ejecta. Unburnt oxygen is present, moving at velocities as high as ~16 700 km s-1, with some intermediate-mass elements (Mg, Si, Ca) moving equally fast. Modeling of the spectra based on standard density profiles of the ejecta fails to reproduce the observed features, whereas enhancing the density of outer layers significantly improves the fit. Our analysis indicates the presence of clumps of high-velocity, intermediate-mass elements in the outermost layers, which is also suggested by the spectropolarimetric data.

  20. THE IMPACT OF TYPE Ia SUPERNOVA EXPLOSIONS ON HELIUM COMPANIONS IN THE CHANDRASEKHAR-MASS EXPLOSION SCENARIO

    SciTech Connect

    Liu Zhengwei; Wang, B.; Han, Z. W.; Pakmor, R.; Seitenzahl, I. R.; Hillebrandt, W.; Kromer, M.; Edelmann, P.; Taubenberger, S.; Roepke, F. K.; Maeda, K.

    2013-09-01

    In the version of the single-degenerate scenario of Type Ia supernovae (SNe Ia) studied here, a carbon-oxygen white dwarf explodes close to the Chandrasekhar limit after accreting material from a non-degenerate helium (He) companion star. In the present study, we employ the STELLAR GADGET code to perform three-dimensional hydrodynamical simulations of the interaction of the SN Ia ejecta with the He companion star taking into account its orbital motion and spin. It is found that only 2%-5% of the initial companion mass is stripped off from the outer layers of He companion stars due to the supernova (SN) impact. The dependence of the unbound mass (or the kick velocity) on the orbital separation can be fitted to a good approximation by a power law for a given companion model. After the SN impact, the outer layers of a He donor star are significantly enriched with heavy elements from the low-expansion-velocity tail of SN Ia ejecta. The total mass of accumulated SN-ejecta material on the companion surface reaches about {approx}> 10{sup -3} M{sub Sun} for different companion models. This enrichment with heavy elements provides a potential way to observationally identify the surviving companion star in SN remnants. Finally, by artificially adjusting the explosion energy of the W7 explosion model, we find that the total accumulation of SN ejecta on the companion surface is also dependent on the explosion energy with a power-law relation to a good approximation.

  1. Turbulence-Flame Interactions in Type Ia Supernovae

    SciTech Connect

    Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720; Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064; Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794; Aspden, Andrew J; Aspden, Andrew J.; Bell, John B.; Day, Marc S.; Woosley, Stan E.; Zingale, Mike

    2008-05-27

    The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to 8 x 107 g cm-3, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and 3 x 107 g cm-3 where the nature of the burning changes ualitatively. By 1 x 107 g cm-3, energy diffusion by conduction and radiation is exceeded, on the flame scale, by turbulent advection. As a result, the effective Lewis Number approaches unity. That is, the flame resembles a laminar flame, but is turbulently broadened with an effective diffusion coefficient, D_T \\sim u' l, where u' is the turbulent intensity and l is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. Implications for a possible transition to detonation are discussed.

  2. Simulating the Double-Degenerate Channel for Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Jumper, Kevin; Fisher, R. T.

    2013-01-01

    Type Ia Supernovae (SNe Ia) are the thermonuclear explosions of white dwarfs, and are of fundamental importance to the study of many phenomena, including the expansion of the universe and dark energy. For many years, it was suspected that that SNe Ia occur in binary systems, but the identity of the white dwarf’s companion could not be determined. A leading hypothesis, the single-degenerate (SD) channel, suggests that the companion is either on the main sequence or a red giant, and that the white dwarf accretes matter off of its companion until it nears the Chandrasekhar limit of 1.4 solar masses, causing the white dwarf to detonate shortly thereafter. Another hypothesis, the double-degenerate (DD) channel, proposes that both stars in the system are white dwarfs and that they merge together, resulting in a central, rapidly spinning white dwarf, surrounded by a thick disk of remnant material. Precisely how this triggers a detonation remains unclear; early spherically-symmetric models by Nomoto et al. indicated that merged white dwarfs would collapse to neutron stars instead of producing supernovae. Recent observations of two supernovae discovered last year by the Palomar Transient Factory (PTF), SN 2011 fe and SN PTF11k, have provided evidence that suggests that both the SD and DD channels coexist in nature. Consequently, it is important to develop simulations that can resolve the mystery of the DD channel’s detonation mechanism. To this end, we use a smoothed-particle hydrodynamics (SPH) code, GADGET-1, to model the rotating flows characteristic of merged DD systems and study how they evolve with time.

  3. SPECTROSCOPIC PROPERTIES OF STAR-FORMING HOST GALAXIES AND TYPE Ia SUPERNOVA HUBBLE RESIDUALS IN A NEARLY UNBIASED SAMPLE

    SciTech Connect

    D'Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Morris, Matt; Nichol, Robert C.; Campbell, Heather; Lampeitl, Hubert; Brown, Peter J.; Olmstead, Matthew D.; Frieman, Joshua A.; Kessler, Richard; Garnavich, Peter; Jha, Saurabh W.; Marriner, John; Schneider, Donald P.; Smith, Mathew

    2011-12-20

    We examine the correlation between supernova (SN) host-galaxy properties and their residuals in the Hubble diagram. We use SNe discovered during the Sloan Digital Sky Survey-II Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova (SN Ia) sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M{sub r} < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star formation rates (SFRs) from host galaxies with active star formation. From a final sample of {approx}40 emission-line galaxies, we find that light-curve-corrected SNe Ia are {approx}0.1 mag brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (>3{sigma}) correlation between the Hubble Residuals of SNe Ia and the specific SFR of the host galaxy. We comment on the importance of SN/host-galaxy correlations as a source of systematic bias in future deep SN surveys.

  4. Near-infrared light curves of Type Ia supernovae: studying properties of the second maximum

    NASA Astrophysics Data System (ADS)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Maguire, K.

    2015-04-01

    Type Ia supernovae (SNe Ia) have been proposed to be much better distance indicators at near-infrared (NIR) compared to optical wavelengths - the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the Y, J and H-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light-curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs ˜ 15 to 30 d after B-band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesized in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.

  5. Incorporating Astrophysical Systematics into a Generalized Likelihood for Cosmology with Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Ponder, Kara A.; Wood-Vasey, W. Michael; Zentner, Andrew R.

    2016-07-01

    Traditional cosmological inference using Type Ia supernovae (SNe Ia) have used stretch- and color-corrected fits of SN Ia light curves and assumed a resulting fiducial mean and symmetric intrinsic dispersion for the resulting relative luminosity. As systematics become the main contributors to the error budget, it has become imperative to expand supernova cosmology analyses to include a more general likelihood to model systematics to remove biases with losses in precision. To illustrate an example likelihood analysis, we use a simple model of two populations with a relative luminosity shift, independent intrinsic dispersions, and linear redshift evolution of the relative fraction of each population. Treating observationally viable two-population mock data using a one-population model results in an inferred dark energy equation of state parameter w that is biased by roughly 2 times its statistical error for a sample of N\\quad ≳ \\quad 2500 SNe Ia. Modeling the two-population data with a two-population model removes this bias at a cost of an approximately ˜ 20 % increase in the statistical constraint on w. These significant biases can be realized even if the support for two underlying SNe Ia populations, in the form of model selection criteria, is inconclusive. With the current observationally estimated difference in the two proposed populations, a sample of N\\quad ≳ \\quad 10,000 SNe Ia is necessary to yield conclusive evidence of two populations.

  6. Spectral classification of SN2016emk as a normal SN Ia at maximum

    NASA Astrophysics Data System (ADS)

    Galbany, L.; Gonzalez-Gaitan, S.

    2016-08-01

    We report optical spectroscopy of the supernova candidate ATSN2016emk (ra 06:03:42.90, dec -35:44:07.20). The spectrum (390-990nm) was obtained on UT 2016 Aug. 1 with the LDSS3 mounted to the Clay telescope at Las Campanas Observatory.

  7. The Distance to NGC 1316 (Fornax A) from Observations of Four Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Stritzinger, Maximilian; Burns, Christopher R.; Phillips, Mark M.; Folatelli, Gastón; Krisciunas, Kevin; Kattner, ShiAnne; Persson, Sven E.; Boldt, Luis; Campillay, Abdo; Contreras, Carlos; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Freedman, Wendy L.; Hamuy, Mario; Madore, Barry F.; Roth, Miguel; Suntzeff, Nicholas B.

    2010-12-01

    The giant elliptical galaxy NGC 1316 (Fornax A) is a well-studied member of the Fornax Cluster and a prolific producer of Type Ia supernovae (SNe Ia), having hosted four observed events since 1980. Here, we present detailed optical- and near-infrared light curves of the spectroscopically normal SN 2006dd. These data are used, along with previously published photometry of the normal SN 1980N and SN 1981D, and the fast-declining, low-luminosity SN 2006mr, to compute independent estimates of the host reddening for each SN, and the distance to NGC 1316. From the three normal SNe, we find a distance of 17.8 ± 0.3 (random) ± 0.3 (systematic) Mpc for Ho = 72. Distance moduli derived from the "EBV" and Tripp methods give the values that are mutually consistent with 4%-8%. Moreover, the weighted means of the distance moduli for these three SNe for three methods agree to within 3%. This consistency is encouraging and supports the premise that Type Ia SNe are reliable distance indicators at the 5% precision level or better. On the other hand, the two methods used to estimate the distance of the fast-declining SN 2006mr both yield a distance to NGC 1316 which is 25%-30% larger. This disparity casts doubt on the suitability of fast-declining events for estimating extragalactic distances. Modest-to-negligible host galaxy reddening values are derived for all four SNe. Nevertheless, two of them (SN 2006dd and SN 2006mr) show strong Na I D interstellar lines in the host galaxy system. The strength of this absorption is completely inconsistent with the small reddening values derived from the SN light curves if the gas in NGC 1316 is typical of that found in the interstellar medium of the Milky Way. In addition, the equivalent width of the Na lines in SN 2006dd appears to have weakened significantly some 100-150 days after explosion. This paper includes data gathered with the 6.5 m Magellan telescope at Las Campanas Observatory, Chile.

  8. A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

    SciTech Connect

    Dilday, Benjamin; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Frieman, Joshua A.; Galbany, Lluis; Garnavich, Peter; Goobar, Ariel; Hopp, Ulrich; /Munich, Tech. U. /Munich U. Observ. /Tokyo U.

    2010-03-01

    We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z {le} 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 {le} z {le} 0.3. We find values for the cluster SN Ia rate of (0.37{sub -0.12-0.01}{sup +0.17+0.01}) SNur h{sup 2} and (0.55{sub -0.11-0.01}{sup +0.13+0.02}) SNur h{sup 2} (SNux = 10{sup -12}L{sub x{circle_dot}}{sup -1} yr{sup -1}) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31{sub -0.12-0.01}{sup +0.18+0.01}) SNur h{sup 2} and (0.49{sub -0.11-0.01}{sup +0.15+0.02}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04{sub -1.11-0.04}{sup +1.99+0.07}) SNur h{sup 2} and (0.36{sub -0.30-0.01}{sup +0.84+0.01}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94{sub -0.91-0.015}{sup +1.31+0.043} and 3.02{sub -1.03-0.048}{sup +1.31+0.062}, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r{sub L} = [(0.49{sub -0.14}{sup +0.15}) + (0.91{sub -0.81}{sup +0.85}) x z] SNuB h{sup 2}. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most 3 hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are

  9. A MEASUREMENT OF THE RATE OF TYPE Ia SUPERNOVAE IN GALAXY CLUSTERS FROM THE SDSS-II SUPERNOVA SURVEY

    SciTech Connect

    Dilday, Benjamin; Jha, Saurabh W.; Bassett, Bruce; Becker, Andrew; Bender, Ralf; Hopp, Ulrich; Castander, Francisco; Cinabro, David; Frieman, Joshua A.; Galbany, LluIs; Miquel, Ramon; Garnavich, Peter; Goobar, Ariel; Ihara, Yutaka; Kessler, Richard; Lampeitl, Hubert; Nichol, Robert C.; Marriner, John; Molla, Mercedes

    2010-06-01

    We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z {<=} 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 {<=} z {<=} 0.3. We find values for the cluster SN Ia rate of (0.37{sup +0.17+0.01} {sub -0.12-0.01}) SNur h {sup 2} and (0.55{sup +0.13+0.02} {sub -0.11-0.01}) SNur h {sup 2} (SNux = 10{sup -12} L {sup -1} {sub xsun} yr{sup -1}) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31{sup +0.18+0.01} {sub -0.12-0.01}) SNur h {sup 2} and (0.49{sup +0.15+0.02} {sub -0.11-0.01}) SNur h {sup 2} in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04{sup +1.99+0.07} {sub -1.11-0.04}) SNur h {sup 2} and (0.36{sup +0.84+0.01} {sub -0.30-0.01}) SNur h {sup 2} in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94{sup +1.31+0.043} {sub -0.91-0.015} and 3.02{sup +1.31+0.062} {sub -1.03-0.048}, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r{sub L} = [(0.49{sup +0.15} {sub -0.14})+(0.91{sup +0.85} {sub -0.81}) x z] SNuB h {sup 2}. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most three hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe

  10. Spectrophotometric time series of SN 2011fe from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Pereira, R.; Thomas, R. C.; Aldering, G.; Antilogus, P.; Baltay, C.; Benitez-Herrera, S.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Chen, J.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Fink, M.; Fouchez, D.; Gangler, E.; Guy, J.; Hillebrandt, W.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Kromer, M.; Nordin, J.; Nugent, P.; Paech, K.; Pain, R.; Pécontal, E.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Smadja, G.; Tao, C.; Taubenberger, S.; Tilquin, A.; Wu, C.

    2013-06-01

    We present 32 epochs of optical (3300-9700 Å) spectrophotometric observations of the nearby quintessential "normal" type Ia supernova (SN Ia) SN 2011fe in the galaxy M101, extending from -15 to +97 d with respect to B-band maximum, obtained by the Nearby Supernova Factory collaboration. SN 2011fe is the closest (μ = 29.04) and brightest (Bmax = 9.94 mag) SN Ia observed since the advent of modern large scale programs for the intensive periodic followup of supernovae. Both synthetic light curve measurements and spectral feature analysis attest to the normality of SN 2011fe. There is very little evidence for reddening in its host galaxy. The homogeneous calibration, intensive time sampling, and high signal-to-noise ratio of the data set make it unique. Thus it is ideal for studying the physics of SN Ia explosions in detail, and for furthering the use of SNe Ia as standardizable candles for cosmology. Several such applications are shown, from the creation of a bolometric light curve and measurement of the 56Ni mass, to the simulation ofdetection thresholds for unburned carbon, direct comparisons with other SNe Ia, and existing spectral templates. A movie is available in electronic form at http://www.aanda.orgAll the reduced spectra are available as FITS files in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5">130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/554/A27

  11. Modified LaRC(TM)-IA Polyimides

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Chang, Alice C.; Hou, Tan H.; Working, Dennis C.

    1994-01-01

    Modified versions of thermoplastic polyimide LaRC(TM)-IA incorporate various amounts of additional, rigid moieties into backbones of LaRC(TM)-IA molecules. Modified versions more resistant to solvents and exhibit higher glass-transition temperatures, yet retain melt-flow processability of unmodified LaRC(TM)-IA.

  12. SN 2012hn: a tidal detonation event?

    NASA Astrophysics Data System (ADS)

    Maccarone, Thomas

    2013-09-01

    We propose for a 30 kilosecond observation of SN 2102hn, a Ca-rich gap transient. These enigmatic objects, with properties intermediate between those of classical novae and Type Ia supernovae, can be well-explained by tidal detonations of low mass white dwarfs by intermediate mass black holes. In such a case, fall-back accretion of the tidal debris would power an X-ray source for which we propose to search. Because supermassive black holes will swallow white dwarfs whole, a successful outcome to this proposal would both explain the Ca-rich gap transients *and* establish the existence of intermediate mass black holes.

  13. RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Piro, Anthony L.

    2012-11-10

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first Almost-Equal-To 0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X {sub 56} Almost-Equal-To (4-6) Multiplication-Sign 10{sup -2} of {sup 56}Ni distributed between a depth of Almost-Equal-To 10{sup -2} and 0.3 M {sub Sun} below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  14. Verifying the Cosmological Utility of Type Ia Supernovae:Implications of a Dispersion in the Ultraviolet Spectra

    SciTech Connect

    Ellis, R.S.; Sullivan, M.; Nugent, P.E.; Howell, D.A.; Gal-Yam,A.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R.G.; Conley,A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I.; Pain, R.; Perrett, K.; Pritchet, C.J.; Regnault, N.

    2007-11-02

    We analyze the mean rest-frame ultraviolet (UV) spectrum ofType Ia Supernovae(SNe) and its dispersion using high signal-to-noiseKeck-I/LRIS-B spectroscopyfor a sample of 36 events at intermediateredshift (z=0.5) discoveredby the Canada-France-Hawaii TelescopeSupernova Legacy Survey (SNLS). Weintroduce a new method for removinghost galaxy contamination in our spectra,exploiting the comprehensivephotometric coverage of the SNLS SNe and theirhost galaxies, therebyproviding the first quantitative view of the UV spectralproperties of alarge sample of distant SNe Ia. Although the mean SN Ia spectrumhas notevolved significantly over the past 40 percent of cosmic history,preciseevolutionary constraints are limited by the absence of acomparable sample ofhigh quality local spectra. The mean UV spectrum ofour z 0.5 SNe Ia and itsdispersion is tabulated for use in futureapplications. Within the high-redshiftsample, we discover significant UVspectral variations and exclude dust extinctionas the primary cause byexamining trends with the optical SN color. Although progenitormetallicity may drive some of these trends, the variations we see aremuchlarger than predicted in recent models and do not follow expectedpatterns.An interesting new result is a variation seen in the wavelengthof selected UVfeatures with phase. We also demonstrate systematicdifferences in the SN Iaspectral features with SN lightcurve width inboth the UV and the optical. Weshow that these intrinsic variations couldrepresent a statistical limitation in thefuture use of high-redshift SNeIa for precision cosmology. We conclude thatfurther detailed studies areneeded, both locally and at moderate redshift wherethe rest-frame UV canbe studied precisely, in order that future missions canconfidently beplanned to fully exploit SNe Ia as cosmological probes.

  15. Predicting polarization signatures for double-detonation and delayed-detonation models of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Bulla, M.; Sim, S. A.; Kromer, M.; Seitenzahl, I. R.; Fink, M.; Ciaraldi-Schoolmann, F.; Röpke, F. K.; Hillebrandt, W.; Pakmor, R.; Ruiter, A. J.; Taubenberger, S.

    2016-10-01

    Calculations of synthetic spectropolarimetry are one means to test multidimensional explosion models for Type Ia supernovae. In a recent paper, we demonstrated that the violent merger of a 1.1 and 0.9 M⊙ white dwarf binary system is too asymmetric to explain the low polarization levels commonly observed in normal Type Ia supernovae. Here, we present polarization simulations for two alternative scenarios: the sub-Chandrasekhar mass double-detonation and the Chandrasekhar mass delayed-detonation model. Specifically, we study a 2D double-detonation model and a 3D delayed-detonation model, and calculate polarization spectra for multiple observer orientations in both cases. We find modest polarization levels (<1 per cent) for both explosion models. Polarization in the continuum peaks at ˜0.1-0.3 per cent and decreases after maximum light, in excellent agreement with spectropolarimetric data of normal Type Ia supernovae. Higher degrees of polarization are found across individual spectral lines. In particular, the synthetic Si II λ6355 profiles are polarized at levels that match remarkably well the values observed in normal Type Ia supernovae, while the low degrees of polarization predicted across the O I λ7774 region are consistent with the non-detection of this feature in current data. We conclude that our models can reproduce many of the characteristics of both flux and polarization spectra for well-studied Type Ia supernovae, such as SN 2001el and SN 2012fr. However, the two models considered here cannot account for the unusually high level of polarization observed in extreme cases such as SN 2004dt.

  16. Diffuse gas in galaxies sheds new light on the origin of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Johansson, Jonas; Woods, Tyrone E.; Gilfanov, Marat; Sarzi, Marc; Chen, Yan-Mei; Oh, Kyuseok

    2014-08-01

    We measure the strength of He II λ4686 nebular emission in passively evolving (`retired') galaxies, aiming to constrain their populations of hot accreting white dwarfs (WDs) in the context of the single-degenerate (SD) scenario of Type Ia supernovae (SNe Ia). In the SD scenario, as a WD burns hydrogen-rich material accreted from a companion star, it becomes a powerful source of ionizing ultraviolet emission. If significant populations of such sources exist in galaxies, strong emission in the recombination lines of He II should be expected from the interstellar medium. To explore this conjecture, we select from the Sloan Digital Sky Survey ˜11 500 emission-line galaxies with stellar ages >1 Gyr showing no signs of active galactic nuclei activity and co-add their spectra in bins of stellar population age. For the first time, we detect He II λ4686 nebular emission in retired galaxies and find it to be significantly weaker than that expected in the SD scenario, especially in the youngest age bin (1-4 Gyr) where the SN Ia rate is the highest. Instead, the strength of the observed He II λ4686 nebular emission is consistent with post-asymptotic giant branch stars being the sole ionizing source in all age bins. These results limit populations of accreting WDs with photospheric temperatures (Teff) in the range ˜(1.5-6) × 105 K to the level at which they can account for no more than ˜5-10 per cent of the observed SN Ia rate. Conversely, should all WD progenitors of SN Ia go through the phase of steady nuclear burning with Teff ˜ (1.5-6) × 105 K, they do not increase their mass by more than ˜0.03 M⊙ in this regime.

  17. Imaging and Demography of the Host Galaxies of High-Redshift Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Williams, Benjamin F.; Hogan, Craig J.; Barris, Brian; Candia, Pablo; Challis, Peter; Clocchiatti, Alejandro; Coil, Alison L.; Filippenko, Alexei V.; Garnavich, Peter; Kirshner, Robert P.; Holland, Stephen T.; Jha, Saurabh; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Maza, Jose; Phillips, Mark M.; Riess, Adam G.; Schmidt, Brian P.; Schommer, Robert A.; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher; Suntzeff, Nicholas B.; Tonry, John L.

    2003-12-01

    We present the results of a study of the host galaxies of high-redshift Type Ia supernovae (SNe Ia). We provide a catalog of 18 hosts of SNe Ia observed with the Hubble Space Telescope (HST) by the High-z Supernova Search Team, including images, scale lengths, measurements of integrated (Hubble-equivalent) BVRIZ photometry in bands where the galaxies are brighter than m~25 mag, and galactocentric distances of the supernovae. We compare the residuals of SN Ia distance measurements from cosmological fits with measurable properties of the supernova host galaxies that might be expected to correlate with variable properties of the progenitor population, such as host-galaxy color and position of the supernova. We find mostly null results; the current data are generally consistent with no correlations of the distance residuals with host-galaxy properties in the redshift range 0.42SN hosts shows a formally significant (3 σ) correlation between apparent V-R host color and distance residuals, the correlation is not consistent with the null results from other host colors probed by our largest samples. There is also evidence for the same correlations between SN Ia properties and host type at low redshift and high redshift. These similarities support the current practice of extrapolating properties of the nearby population to high redshifts, pending more robust detections of any correlations between distance residuals from cosmological fits and host properties. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555.

  18. Lightcurves of Type Ia Supernovae from Near the Time of Explosion

    SciTech Connect

    Garg, A; Stubbs, C W; Challis, P; Wood-Vasey, M; Blondin, S; Huber, M E; Cook, K; Nikolaev, S; Rest, A; Smith, R C; Olsen, K; Suntzeff, N B; Aguilera, C; Prieto, J L; Becker, A; Miceli, A; Miknaitis, G; Clocchiatti, A; Minniti, D; Morelli, L; Welch, D

    2006-08-30

    We present a set of 11 type Ia supernova (SN Ia) lightcurves with dense, pre-maximum sampling. These supernovae (SNe), in galaxies behind the Large Magellanic Cloud (LMC), were discovered by the SuperMACHO survey. The SNe span a redshift range of z = 0.11-0.35. Our lightcurves contain some of the earliest pre-maximum observations of SNe Ia to date. We also give a functional model that describes the SN Ia lightcurve shape (in our V R-band). Our function uses the ''expanding fireball'' model of Goldhaber et al. (1998) to describe the rising lightcurve immediately after explosion but constrains it to smoothly join the remainder of the lightcurve. We fit this model to a composite observed V R-band lightcurve of three SNe between redshifts of 0.135 to 0.165. These SNe have not been K-corrected or adjusted to account for reddening. In this redshift range, the observed V R-band most closely matches the rest frame V-band. Using the best fit to our functional description of the lightcurve, we find the time between explosion and observed V R-band maximum to be 19.2 {+-} 1.3-1.6 {+-} 0.07(red.) rest-frame days for a SN Ia with a V R-band {Delta}m{sub -10} of 0.52. For the redshifts sampled, the observed V R-band time-of-maximum brightness should be the same as the rest-frame V -band maximum to within 1.1 rest-frame days.

  19. WHITE DWARF/M DWARF BINARIES AS SINGLE DEGENERATE PROGENITORS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Wheeler, J. Craig

    2012-10-20

    Limits on the companions of white dwarfs in the single-degenerate scenario for the origin of Type Ia supernovae (SNe Ia) have gotten increasingly tight, yet igniting a nearly Chandrasekhar mass C/O white dwarf from a condition of near hydrostatic equilibrium provides compelling agreement with observed spectral evolution. The only type of non-degenerate stars that survive the tight limits, M{sub V} {approx}> 8.4 on the SN Ia in SNR 0509-67.5 and M{sub V} {approx}> 9.5 in the remnant of SN 1572, are M dwarfs. While M dwarfs are observed in cataclysmic variables, they have special properties that have not been considered in most work on the progenitors of SNe Ia: they have small but finite magnetic fields and they flare frequently. These properties are explored in the context of SN Ia progenitors. White dwarf/M dwarf pairs may be sufficiently plentiful to provide, in principle, an adequate rate of explosions even with slow orbital evolution due to magnetic braking or gravitational radiation. Even modest magnetic fields on the white dwarf and M dwarf will yield adequate torques to lock the two stars together, resulting in a slowly rotating white dwarf, with the magnetic poles pointing at one another in the orbital plane. The mass loss will be channeled by a 'magnetic bottle' connecting the two stars, landing on a concentrated polar area on the white dwarf. This enhances the effective rate of accretion compared to spherical accretion. Luminosity from accretion and hydrogen burning on the surface of the white dwarf may induce self-excited mass transfer. The combined effects of self-excited mass loss, polar accretion, and magnetic inhibition of mixing of accretion layers give possible means to beat the 'nova limit' and grow the white dwarf to the Chandrasekhar mass even at rather moderate mass accretion rates.

  20. Near-Explosion Lightcurves of SNe Ia from the SuperMACHO Survey

    NASA Astrophysics Data System (ADS)

    Garg, Arti; Stubbs, C. W.; Challis, P.; Wood-Vasey, W.; Blondin, S.; Huber, M. E.; Cook, K.; Nikolaev, S.; Rest, A.; Smith, R.; Olsen, K.; Suntzeff, N. B.; Aguilera, C.; Prieto, J. L.; Becker, A.; Miceli, A.; Miknaitis, G.; Clocchiatti, A.; Minniti, D.; Morelli, L.; Welch, D. L.

    2006-12-01

    We present a set four type Ia supernova (SN Ia) lightcurves with dense, pre-maximum sampling. These supernovae (SNe), in galaxies behind the Large Magellanic Cloud (LMC), were discovered by the SuperMACHO survey and span a redshift range of 0.145 to 0.16. Our lightcurves contain some of the earliest pre-maximum observations of SNe Ia to date. We also give a functional model that describes the SN Ia lightcurve shape (in our VR-band). Our function uses the "expanding fireball" model of Goldhaber et al. (1998) to describe the rising lightcurve immediately after explosion but constrains it to smoothly join the remainder of the lightcurve. We fit this model to a composite observed VR-band lightcurve of three SNe. These SNe have not been K-corrected or adjusted to account for reddening. In this redshift range, the observed VR-band most closely matches the rest frame V-band. Using the best fit to our functional description of the lightcurve, we find the time between explosion and observed VR-band maximum to be 17.6±1.3(stat)±0.07(sys) rest-frame days for a SN Ia with a VR-band Δm_-10 of 0.52mag. For the redshifts sampled, the observed VR-band time-of-maximum brightness should be the same as the rest-frame V-band maximum to within 1.1 rest-frame days.

  1. TYPE Ia SUPERNOVA LIGHT CURVE INFERENCE: HIERARCHICAL MODELS IN THE OPTICAL AND NEAR-INFRARED

    SciTech Connect

    Mandel, Kaisey S.; Narayan, Gautham; Kirshner, Robert P.

    2011-04-20

    We have constructed a comprehensive statistical model for Type Ia supernova (SN Ia) light curves spanning optical through near-infrared (NIR) data. A hierarchical framework coherently models multiple random and uncertain effects, including intrinsic supernova (SN) light curve covariances, dust extinction and reddening, and distances. An improved BAYESN Markov Chain Monte Carlo code computes probabilistic inferences for the hierarchical model by sampling the global probability density of parameters describing individual SNe and the population. We have applied this hierarchical model to optical and NIR data of 127 SNe Ia from PAIRITEL, CfA3, Carnegie Supernova Project, and the literature. We find an apparent population correlation between the host galaxy extinction A{sub V} and the ratio of total-to-selective dust absorption R{sub V} . For SNe with low dust extinction, A{sub V} {approx}< 0.4, we find R{sub V} {approx} 2.5-2.9, while at high extinctions, A{sub V} {approx}> 1, low values of R{sub V} < 2 are favored. The NIR luminosities are excellent standard candles and are less sensitive to dust extinction. They exhibit low correlation with optical peak luminosities, and thus provide independent information on distances. The combination of NIR and optical data constrains the dust extinction and improves the predictive precision of individual SN Ia distances by about 60%. Using cross-validation, we estimate an rms distance modulus prediction error of 0.11 mag for SNe with optical and NIR data versus 0.15 mag for SNe with optical data alone. Continued study of SNe Ia in the NIR is important for improving their utility as precise and accurate cosmological distance indicators.

  2. White Dwarf/M Dwarf Binaries as Single Degenerate Progenitors of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Wheeler, J. Craig

    2012-10-01

    Limits on the companions of white dwarfs in the single-degenerate scenario for the origin of Type Ia supernovae (SNe Ia) have gotten increasingly tight, yet igniting a nearly Chandrasekhar mass C/O white dwarf from a condition of near hydrostatic equilibrium provides compelling agreement with observed spectral evolution. The only type of non-degenerate stars that survive the tight limits, MV >~ 8.4 on the SN Ia in SNR 0509-67.5 and MV >~ 9.5 in the remnant of SN 1572, are M dwarfs. While M dwarfs are observed in cataclysmic variables, they have special properties that have not been considered in most work on the progenitors of SNe Ia: they have small but finite magnetic fields and they flare frequently. These properties are explored in the context of SN Ia progenitors. White dwarf/M dwarf pairs may be sufficiently plentiful to provide, in principle, an adequate rate of explosions even with slow orbital evolution due to magnetic braking or gravitational radiation. Even modest magnetic fields on the white dwarf and M dwarf will yield adequate torques to lock the two stars together, resulting in a slowly rotating white dwarf, with the magnetic poles pointing at one another in the orbital plane. The mass loss will be channeled by a "magnetic bottle" connecting the two stars, landing on a concentrated polar area on the white dwarf. This enhances the effective rate of accretion compared to spherical accretion. Luminosity from accretion and hydrogen burning on the surface of the white dwarf may induce self-excited mass transfer. The combined effects of self-excited mass loss, polar accretion, and magnetic inhibition of mixing of accretion layers give possible means to beat the "nova limit" and grow the white dwarf to the Chandrasekhar mass even at rather moderate mass accretion rates.

  3. The peculiar Type Ia supernova iPTF14atg: Chandrasekhar-mass explosion or violent merger?

    NASA Astrophysics Data System (ADS)

    Kromer, M.; Fremling, C.; Pakmor, R.; Taubenberger, S.; Amanullah, R.; Cenko, S. B.; Fransson, C.; Goobar, A.; Leloudas, G.; Taddia, F.; Röpke, F. K.; Seitenzahl, I. R.; Sim, S. A.; Sollerman, J.

    2016-07-01

    iPTF14atg, a subluminous peculiar Type Ia supernova (SN Ia) similar to SN 2002es, is the first SN Ia for which a strong UV flash was observed in the early-time light curves. This has been interpreted as evidence for a single-degenerate (SD) progenitor system, where such a signal is expected from interactions between the SN ejecta and the non-degenerate companion star. Here, we compare synthetic observables of multidimensional state-of-the-art explosion models for different progenitor scenarios to the light curves and spectra of iPTF14atg. From our models, we have difficulties explaining the spectral evolution of iPTF14atg within the SD progenitor channel. In contrast, we find that a violent merger of two carbon-oxygen white dwarfs with 0.9 and 0.76 M⊙, respectively, provides an excellent match to the spectral evolution of iPTF14atg from 10 d before to several weeks after maximum light. Our merger model does not naturally explain the initial UV flash of iPTF14atg. We discuss several possibilities like interactions of the SN ejecta with the circumstellar medium and surface radioactivity from an He-ignited merger that may be able to account for the early UV emission in violent merger models.

  4. THE PROGENITORS OF TYPE Ia SUPERNOVAE. I. ARE THEY SUPERSOFT SOURCES?

    SciTech Connect

    Di Stefano, R.

    2010-03-20

    In a canonical model, the progenitors of Type Ia supernovae (SNe Ia) are accreting, nuclear-burning white dwarfs (NBWDs), which explode when the white dwarf reaches the Chandrasekhar mass, M{sub C} . Such massive NBWDs are hot (kT {approx} 100 eV), luminous (L {approx} 10{sup 38} erg s{sup -1}), and are potentially observable as luminous supersoft X-ray sources (SSSs). During the past several years, surveys for soft X-ray sources in external galaxies have been conducted. This paper shows that the results falsify the hypothesis that a large fraction of progenitors are NBWDs which are presently observable as SSSs. The data also place limits on sub-M{sub C} models. While SN Ia progenitors may pass through one or more phases of SSS activity, these phases are far shorter than the time needed to accrete most of the matter that brings them close to M{sub C} .

  5. Type Ia and II Supernovae Contributions to Metal Enrichment in the Intracluster Medium Observed with Suzaku

    NASA Astrophysics Data System (ADS)

    Sato, Kosuke; Tokoi, Kazuyo; Matsushita, Kyoko; Ishisaki, Yoshitaka; Yamasaki, Noriko Y.; Ishida, Manabu; Ohashi, Takaya

    2007-09-01

    We studied the properties of the intracluster medium (ICM) in two clusters of galaxies (AWM 7 and Abell 1060) and two groups (HCG 62 and NGC 507) with the X-ray observatory Suzaku. Based on spatially resolved energy spectra, we measured for the first time precise cumulative ICM metal masses within 0.1 and ~0.3r180. Comparing our results with supernova nucleosynthesis models, the number ratio of Type II (SNe II) to Type Ia (SNe Ia) is estimated to be ~3.5, assuming the metal mass in the ICM is represented by the sum of products synthesized in SNe Ia and SNe II. Normalized by the K-band luminosities of present galaxies, and including the metals in stars, the integrated number of past SN II explosions is estimated to be close to or somewhat higher than the star formation rate determined from Hubble Deep Field observations.

  6. FLOYDS Classification of ATLAS16cxr as a Young Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Arcavi, I.; Howell, D. A.; McCully, C.; Valenti, S.

    2016-09-01

    We obtained a spectrum of ATLAS16cxr (ATel #9535) on 2016 September 25.3 UT with the robotic FLOYDS instrument mounted on the LCOGT 2-meter telescope on Haleakala, Hawai'i. Using Superfit (Howell et al. 2005, ApJ, 634, 1190), we find a good fit to the normal Type Ia SN 1994D 8 days before maximum light at redshift z=0.016.

  7. THE EARLIEST NEAR-INFRARED TIME-SERIES SPECTROSCOPY OF A TYPE Ia SUPERNOVA

    SciTech Connect

    Hsiao, E. Y.; Phillips, M. M.; Morrell, N.; Contreras, C.; Roth, M.; Marion, G. H.; Kirshner, R. P.; Burns, C. R.; Freedman, W. L.; Persson, S. E.; Winge, C.; Gerardy, C. L.; Hoeflich, P.; Im, M.; Jeon, Y.; Pignata, G.; Stanishev, V.; and others

    2013-04-01

    We present ten medium-resolution, high signal-to-noise ratio near-infrared (NIR) spectra of SN 2011fe from SpeX on the NASA Infrared Telescope Facility (IRTF) and Gemini Near-Infrared Spectrograph (GNIRS) on Gemini North, obtained as part of the Carnegie Supernova Project. This data set constitutes the earliest time-series NIR spectroscopy of a Type Ia supernova (SN Ia), with the first spectrum obtained at 2.58 days past the explosion and covering -14.6 to +17.3 days relative to B-band maximum. C I {lambda}1.0693 {mu}m is detected in SN 2011fe with increasing strength up to maximum light. The delay in the onset of the NIR C I line demonstrates its potential to be an effective tracer of unprocessed material. For the first time in a SN Ia, the early rapid decline of the Mg II {lambda}1.0927 {mu}m velocity was observed, and the subsequent velocity is remarkably constant. The Mg II velocity during this constant phase locates the inner edge of carbon burning and probes the conditions under which the transition from deflagration to detonation occurs. We show that the Mg II velocity does not correlate with the optical light-curve decline rate {Delta}m{sub 15}(B). The prominent break at {approx}1.5 {mu}m is the main source of concern for NIR k-correction calculations. We demonstrate here that the feature has a uniform time evolution among SNe Ia, with the flux ratio across the break strongly correlated with {Delta}m{sub 15}(B). The predictability of the strength and the onset of this feature suggests that the associated k-correction uncertainties can be minimized with improved spectral templates.

  8. Helium Star Donor Channel to Type Ia Supernovae and Their Surviving Companion Stars

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Han, Zhanwen

    2013-01-01

    Employing Eggleton's stellar evolution code and assuming optically thick winds, we systematically studied the He star donor channel of Type Ia supernovae (SNe Ia), in which a carbon-oxygen white dwarf (WD) accretes material from a He main-sequence star or a He subgiant to increase its mass to the Chandrasekhar mass. We mapped out the initial parameters for producing SNe Ia in the orbital period-secondary mass plane for various WD masses from this channel. Based on a detailed binary population synthesis approach, we find that this channel can produce SNe Ia with short delay times (~100 Myr) implied by recent observations. We derived many properties of the surviving companions of this channel after SN explosion, which can be tested by future observations. We also find that the surviving companions from the SN explosion scenario have a high spatial velocity (>400 km/s), which could be an alternative origin for hypervelocity stars (HVSs), especially for HVSs such as US 708.

  9. A reddening-free method to estimate the 56Ni mass of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Blondin, S.

    2016-04-01

    The increase in the number of Type Ia supernovae (SNe Ia) has demonstrated that the population shows greater diversity than has been assumed in the past. The reasons (e.g. parent population, explosion mechanism) for this diversity remain largely unknown. We investigated a sample of SNe Ia near-infrared light curves and correlated the phase of the second maximum with the bolometric peak luminosity. The peak bolometric luminosity is related to the time of the second maximum (relative to the B light curve maximum) as follows: Lmax(1043 erg s-1) = (0.039 ± 0.004) × t2(J)(days) + (0.013 ± 0.106). 56Ni masses can be derived from the peak luminosity based on Arnett's rule, which states that the luminosity at maximum is equal to the instantaneous energy generated by the nickel decay. We checked this assumption against recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models and find this assumption is valid to within 10% in recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models. The Lmax vs. t2 relation is applied to a sample of 40 additional SNe Ia with significant reddening (E(B - V) > 0.1 mag), and a reddening-free bolometric luminosity function of SNe Ia is established. The method is tested with the 56Ni mass measurement from the direct observation of γ-rays in the heavily absorbed SN 2014J and found to be fully consistent. Super-Chandrasekhar-mass explosions, in particular SN 2007if, do not follow the relations between peak luminosity and second IR maximum. This may point to an additional energy source contributing at maximum light. The luminosity function of SNe Ia is constructed and is shown to be asymmetric with a tail of low-luminosity objects and a rather sharp high-luminosity cutoff, although it might be influenced by selection effects.

  10. Ultraviolet observations of Super-Chandrasekhar mass type Ia supernova candidates with swift UVOT

    SciTech Connect

    Brown, Peter J.; Smitka, Michael T.; Krisciunas, Kevin; Wang, Lifan; Kuin, Paul; De Pasquale, Massimiliano; Scalzo, Richard; Holland, Stephen; Milne, Peter

    2014-05-20

    Among Type Ia supernovae (SNe Ia), a class of overluminous objects exist whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe—2009dc, 2011aa, and 2012dn—observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN 2011aa being among the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of 'normal' SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 Å) are only half as bright as SN 2009dc, implying a smaller {sup 56}Ni yield. While it is not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and {sup 56}Ni masses of SNe 2011aa and 2012dn and to fully explain their high UV luminosities.

  11. The Type-Ia Supernova 1998bu in M96 and the Hubble Constant

    NASA Astrophysics Data System (ADS)

    Jha, S.; Garnavich, P. M.; Challis, P. M.; Kirshner, R. P.; Riess, A. G.; Filippenko, A. V.; Li, W.; Modjaz, M.; Treffers, R. R.; Grebel, E. K.; Seitzer, P.; Jacoby, G. H.; Benson, P. J.; Rizvi, A.; Marschall, L. A.

    1998-12-01

    We present extensive early-time photometric and spectroscopic observations of the type-Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The well-sampled optical light curves consist of 311 UBVRI observations obtained from several telescopes: the F. L. Whipple Observatory 1.2-m, the MDM Observatory 2.4-m, the WIYN Observatory 3.5-m, the Kitt Peak National Observatory 0.9-m, the Whitin Observatory 0.6-m at Wellesley College, the Gettysburg College Observatory 0.4-m and the 0.76-m Katzman Automatic Imaging Telescope operated by UC Berkeley. The supernova reached maximum brightness in the B band on JD 2450952.8 +/- 0.8, with B = 12.22 +/- 0.03 and V = 11.88 +/- 0.02. There is strong evidence for considerable interstellar extinction along the line of sight to the supernova, but the light curve is otherwise quite typical of type-Ia supernovae (SNe Ia). The distance to M96 has been measured via HST observations of Cepheids in the galaxy (Tanvir et al. 1995), making SN 1998bu very useful in determining the absolute luminosity of SNe Ia. We combine these observations with those of other Cepheid-calibrated SNe Ia and SNe Ia in the Hubble flow and perform a Multicolor Light Curve Shape analysis to derive a Hubble Constant of 64 +/- 4 km/s/Mpc (internal error), but subject to several sources of systematic uncertainty in the Cepheid distance scale.

  12. SN 2014J and the Harvard Observing Project

    NASA Astrophysics Data System (ADS)

    McIntosh, Melissa; Bieryla, Allyson; Newton, Elisabeth R.; Lewis, John A.; Vanderburg, Andrew; Alexander, Kate Denham; Blanchard, Peter

    2014-06-01

    A chance discovery on January 21, 2014 by Steve Fossey et al. of University College London during an undergraduate telescope training session revealed the closest type Ia supernova in the past 42 years. The bright SN 2014J was observed by undergraduates and graduate students alike in the Harvard Observing Project (see poster by A. Bieryla) with the Clay Telescope at Harvard University. Observations were obtained in multiple filters starting January 24, 2014, prior to the supernova reaching its peak brightness, and monitoring will continue as the supernova fades in brightness. We will present multiple band light curve photometry and color RGB images of SN 2014J and its host galaxy M82.

  13. Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report

    SciTech Connect

    Filippenko, Alexei Vladimir

    2014-05-09

    Type Ia supernovae (SNe Ia; exploding white-dwarf stars) were the key to the Nobel-worthy 1998 discovery and subsequent verification that the expansion of the Universe is accelerating, driven by the effects of dark energy. Understanding the nature of this mysterious, yet dominant, component of the Universe is at the forefront of research in cosmology and fundamental physics. SNe Ia will continue to play a leading role in this enterprise, providing precise cosmological distances that improve constraints on the nature of dark energy. However, for this effort to succeed, we need to more thoroughly understand relatively nearby SNe Ia, because our conclusions come only from comparisons between them and distant (high-redshift) SNe Ia. Thus, detailed studies of relatively nearby SNe Ia are the focus of this research program. Many interesting results were obtained during the course of this project; these were published in 32 refereed research papers that acknowledged the grant. A major accomplishment was the publication of supernova (SN) rates derived from about a decade of operation of the Lick Observatory Supernova Search (LOSS) with the 0.76-meter Katzman Automatic Imaging Telescope (KAIT). We have determined the most accurate rates for SNe of different types in large, nearby galaxies in the present-day Universe, and these can be compared with SN rates far away (and hence long ago in the past) to set constraints on the types of stars that explode. Another major accomplishment was the publication of the light curves (brightness vs. time) of 165 SNe Ia, along with optical spectroscopy of many of these SNe as well as other SNe Ia, providing an extensive, homogeneous database for detailed studies. We have conducted intensive investigations of a number of individual SNe Ia, including quite unusual examples that allow us to probe the entire range of SN explosions and provide unique insights into these objects and the stars before they explode. My team's studies have also led

  14. Quark-novae in neutron star - white dwarf binaries: a model for luminous (spin-down powered) sub-Chandrasekhar-mass Type Ia supernovae?

    NASA Astrophysics Data System (ADS)

    Ouyed, Rachid; Staff, Jan

    2013-04-01

    We show that, by appealing to a Quark-Nova (QN) in a tight binary system containing a massive neutron star and a CO white dwarf (WD), a Type Ia explosion could occur. The QN ejecta collides with the WD, driving a shock that triggers carbon burning under degenerate conditions (the QN-Ia). The conditions in the compressed low-mass WD (MWD < 0.9 Msolar) in our model mimic those of a Chandrasekhar mass WD. The spin-down luminosity from the QN compact remnant (the quark star) provides additional power that makes the QN-Ia light-curve brighter and broader than a standard SN-Ia with similar 56Ni yield. In QNe-Ia, photometry and spectroscopy are not necessarily linked since the kinetic energy of the ejecta has a contribution from spin-down power and nuclear decay. Although QNe-Ia may not obey the Phillips relationship, their brightness and their relatively “normal looking" light-curves mean they could be included in the cosmological sample. Light-curve fitters would be confused by the discrepancy between spectroscopy at peak and photometry and would correct for it by effectively brightening or dimming the QNe-Ia apparent magnitudes, thus over- or under-estimating the true magnitude of these spin-down powered SNe-Ia. Contamination of QNe-Ia in samples of SNe-Ia used for cosmological analyses could systematically bias measurements of cosmological parameters if QNe-Ia are numerous enough at high-redshift. The strong mixing induced by spin-down wind combined with the low 56Ni yields in QNe-Ia means that these would lack a secondary maximum in the i-band despite their luminous nature. We discuss possible QNe-Ia progenitors.

  15. Supernova Acceleration Probe: Studying Dark Energy with Type Ia Supernovae

    SciTech Connect

    Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Aumeunier, M.; Bailey, S.; Baltay, C.; Barrelet, E.; Basa, S.; Bebek, C.; Bergstom, L.; Bernstein, G.; Bester, M.; Besuner, B.; Bigelow, B.; Blandford, R.; Bohlin, R.; Bonissent, A.; /Caltech /LBL, Berkeley /Fermilab /SLAC /Stockholm U. /Paris, IN2P3 /Marseille, CPPM /Marseille, Lab. Astrophys. /Yale U. /Pennsylvania U. /UC, Berkeley /Michigan U. /Baltimore, Space Telescope Sci. /Indiana U. /Caltech, JPL /Australian Natl. U., Canberra /American Astron. Society /Chicago U. /Cambridge U. /Saclay /Lyon, IPN

    2005-08-08

    The Supernova Acceleration Probe (SNAP) will use Type Ia supernovae (SNe Ia) as distance indicators to measure the effect of dark energy on the expansion history of the Universe. (SNAP's weak-lensing program is described in a separate White Paper.) The experiment exploits supernova distance measurements up to their fundamental systematic limit; strict requirements on the monitoring of each supernova's properties leads to the need for a space-based mission. Results from pre-SNAP experiments, which characterize fundamental SN Ia properties, will be used to optimize the SNAP observing strategy to yield data, which minimize both systematic and statistical uncertainties. With early R&D funding, we have achieved technological readiness and the collaboration is poised to begin construction. Pre-JDEM AO R&D support will further reduce technical and cost risk. Specific details on the SNAP mission can be found in Aldering et al. (2004, 2005). The primary goal of the SNAP supernova program is to provide a dataset which gives tight constraints on parameters which characterize the dark-energy, e.g. w{sub 0} and w{sub a} where w(a) = w{sub 0} + w{sub a}(1-a). SNAP data can also be used to directly test and discriminate among specific dark energy models. We will do so by building the Hubble diagram of high-redshift supernovae, the same methodology used in the original discovery of the acceleration of the expansion of the Universe that established the existence of dark energy (Perlmutter et al. 1998; Garnavich et al. 1998; Riess et al. 1998; Perlmutter et al. 1999). The SNAP SN Ia program focuses on minimizing the systematic floor of the supernova method through the use of characterized supernovae that can be sorted into subsets based on subtle signatures of heterogeneity. Subsets may be defined based on host-galaxy morphology, spectral-feature strength and velocity, early-time behavior, inter alia. Independent cosmological analysis of each subset of ''like'' supernovae can be

  16. Berkeley Supernova Ia Program - III. Spectra near maximum brightness improve the accuracy of derived distances to Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Ganeshalingam, Mohan; Li, Weidong; Filippenko, Alexei V.

    2012-09-01

    In this third paper in a series we compare spectral feature measurements to photometric properties of 108 low-redshift (z < 0.1, ≈ 0.023) Type Ia supernovae (SNe Ia) for which we have optical spectra within 5 d of maximum brightness. The spectral data were obtained from 1989 to the end of 2008 as part of the Berkeley Supernova Ia Program (BSNIP) and are presented in BSNIP I by Silverman et al., and the photometric data come mainly from the Lick Observatory Supernova Search and are published by Ganeshalingam et al. The spectral measurements are presented and discussed in BSNIP II by Silverman, Kong & Filippenko, and the light-curve fits and photometric parameters can be found in Ganeshalingam et al. (in preparation). A variety of previously proposed correlations between spectral and photometric parameters are investigated using the large and self-consistent BSNIP data set. We find the pseudo-equivalent width (pEW) of the Si II λ4000 line to be a good indicator of light-curve width, and the pEWs of the Mg II and Fe II complexes are relatively good proxies for SN colour. We also employ a combination of light-curve parameters (specifically the Spectral Adaptive Light-curve Template 2 stretch and colour parameters x1 and c, respectively) and spectral measurements to calculate distance moduli. The residuals from these models are then compared to the standard model which uses only light-curve stretch and colour. Our investigations show that a distance model that uses x1, c and the velocity of the Si II λ6355 feature does not lead to a decrease in the Hubble residuals. We also find that distance models with flux ratios alone or in conjunction with light-curve information rarely perform better than the standard (x1, c) model. However, when adopting a distance model which combines the ratio of fluxes near ˜3750 and 4550 Å with both x1 and c, the Hubble residuals are decreased by ˜10 per cent, which is found to be significant at about the 2σ level. The weighted

  17. Progenitors of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Raskin, Cody

    Type Ia supernovae are important, but mysterious cosmological tools. Their standard brightnesses have enabled cosmologists to measure extreme distances and to discover dark energy. However, the nature of their progenitor mechanisms remains elusive, with many competing models offering only partial clues to their origins. Here, type Ia supernova delay times are explored using analytical models. Combined with a new observation technique, this model places new constraints on the characteristic time delay between the formation of stars and the first type Ia supernovae. This derived delay time (500 million years) implies low-mass companions for single degenerate progenitor scenarios. In the latter portions of this dissertation, two progenitor mechanisms are simulated in detail; white dwarf collisions and mergers. From the first of these simulations, it is evident that white dwarf collisions offer a viable and unique pathway to producing type Ia supernovae. Many of the combinations of masses simulated produce sufficient quantities of 56 Ni (up to 0.51 solar masses) to masquerade as normal type Ia supernovae. Other combinations of masses produce 56 Ni yields that span the entire range of supernova brightnesses, from the very dim and underluminous, with 0.14 solar masses, to the over-bright and superluminous, with up to 1.71 solar masses. The 56 Ni yield in the collision simulations depends non-linearly on total system mass, mass ratio, and impact parameter. Using the same numerical tools as in the collisions examination, white dwarf mergers are studied in detail. Nearly all of the simulations produce merger remnants consisting of a cold, degenerate core surrounded by a hot accretion disk. The properties of these disks have strong implications for various viscosity treatments that have attempted to pin down the accretion times. Some mass combinations produce super-Chandrasekhar cores on shorter time scales than viscosity driven accretion. A handful of simulations also

  18. Consistent use of type Ia supernovae highly magnified by galaxy clusters to constrain the cosmological parameters

    SciTech Connect

    Zitrin, Adi; Redlich, Matthias; Broadhurst, Tom

    2014-07-01

    We discuss how Type Ia supernovae (SNe) strongly magnified by foreground galaxy clusters should be self-consistently treated when used in samples fitted for the cosmological parameters. While the cluster lens magnification of a SN can be well constrained from sets of multiple images of various background galaxies with measured redshifts, its value is typically dependent on the fiducial set of cosmological parameters used to construct the mass model. In such cases, one should not naively demagnify the observed SN luminosity by the model magnification into the expected Hubble diagram, which would create a bias, but instead take into account the cosmological parameters a priori chosen to construct the mass model. We quantify the effect and find that a systematic error of typically a few percent, up to a few dozen percent per magnified SN may be propagated onto a cosmological parameter fit unless the cosmology assumed for the mass model is taken into account (the bias can be even larger if the SN is lying very near the critical curves). We also simulate how such a bias propagates onto the cosmological parameter fit using the Union2.1 sample supplemented with strongly magnified SNe. The resulting bias on the deduced cosmological parameters is generally at the few percent level, if only few biased SNe are included, and increases with the number of lensed SNe and their redshift. Samples containing magnified Type Ia SNe, e.g., from ongoing cluster surveys, should readily account for this possible bias.

  19. The Oxygen Features in Type Ia Supernovae and Implications for the Nature of Thermonuclear Explosions

    NASA Astrophysics Data System (ADS)

    Zhao, Xulin; Maeda, Keiichi; Wang, Xiaofeng; Wang, Lifan; Sai, Hanna; Zhang, Jujia; Zhang, Tianmeng; Huang, Fang; Rui, Liming

    2016-08-01

    The absorption feature O i λ7773 is an important spectral indicator for type Ia supernovae (SNe Ia) that can be used to trace the unburned material in outer layers of the exploding white dwarf (WD). In this work, we use a large sample of SNe Ia to examine this absorption at early phases (i.e., -13 day ≲ t ≲ -7 day) and make comparisons with the absorption features of Si ii λ6355 and the Ca ii near-infrared triplet. We show that for a subgroup of spectroscopically normal SNe with normal photospheric velocities (i.e., v si ≲ 12,500 km s-1 at optical maximum), the line strength of the high velocity feature (HVF) of O i is inversely correlated with that of Si ii (or Ca ii), and this feature also shows a negative correlation with the luminosity of SNe Ia. This finding, together with other features we find for the O i HVF, reveal that for this subgroup of SNe Ia, explosive oxygen burning occurs in the outermost layer of the SN. Differences in the oxygen burning could lead to the observed diversity, which is in remarkable agreement with the popular delayed-detonation model of Chandrasekhar mass WDs.

  20. Wind-driven evolution of white dwarf binaries to type Ia supernovae

    SciTech Connect

    Ablimit, Iminhaji; Xu, Xiao-jie; Li, X.-D.

    2014-01-01

    In the single-degenerate scenario for the progenitors of Type Ia supernovae (SNe Ia), a white dwarf rapidly accretes hydrogen- or helium-rich material from its companion star and appears as a supersoft X-ray source. This picture has been challenged by the properties of the supersoft X-ray sources with very low mass companions and the observations of several nearby SNe Ia. It has been pointed out that the X-ray radiation or the wind from the accreting white dwarf can excite winds or strip mass from the companion star, thus significantly influencing the mass transfer processes. In this paper, we perform detailed calculations of the wind-driven evolution of white dwarf binaries. We present the parameter space for the possible SN Ia progenitors and for the surviving companions after the SNe. The results show that the ex-companion stars of SNe Ia have characteristics more compatible with the observations, compared with those in the traditional single-degenerate scenario.

  1. The Oxygen Features in Type Ia Supernovae and Implications for the Nature of Thermonuclear Explosions

    NASA Astrophysics Data System (ADS)

    Zhao, Xulin; Maeda, Keiichi; Wang, Xiaofeng; Wang, Lifan; Sai, Hanna; Zhang, Jujia; Zhang, Tianmeng; Huang, Fang; Rui, Liming

    2016-08-01

    The absorption feature O i λ7773 is an important spectral indicator for type Ia supernovae (SNe Ia) that can be used to trace the unburned material in outer layers of the exploding white dwarf (WD). In this work, we use a large sample of SNe Ia to examine this absorption at early phases (i.e., ‑13 day ≲ t ≲ ‑7 day) and make comparisons with the absorption features of Si ii λ6355 and the Ca ii near-infrared triplet. We show that for a subgroup of spectroscopically normal SNe with normal photospheric velocities (i.e., v si ≲ 12,500 km s‑1 at optical maximum), the line strength of the high velocity feature (HVF) of O i is inversely correlated with that of Si ii (or Ca ii), and this feature also shows a negative correlation with the luminosity of SNe Ia. This finding, together with other features we find for the O i HVF, reveal that for this subgroup of SNe Ia, explosive oxygen burning occurs in the outermost layer of the SN. Differences in the oxygen burning could lead to the observed diversity, which is in remarkable agreement with the popular delayed-detonation model of Chandrasekhar mass WDs.

  2. Tycho Brahe's 1572 supernova as a standard type Ia as revealed by its light-echo spectrum.

    PubMed

    Krause, Oliver; Tanaka, Masaomi; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-12-01

    Type Ia supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a type Ia supernova in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of type Ia supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN 1572 belongs to the majority class of normal type Ia supernovae. PMID:19052622

  3. Tycho Brahe's 1572 supernova as a standard typeIa as revealed by its light-echo spectrum

    NASA Astrophysics Data System (ADS)

    Krause, Oliver; Tanaka, Masaomi; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-12-01

    TypeIa supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN1572) is thought to be one of the best candidates for a typeIa supernova in the Milky Way. The proximity of the SN1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of typeIa supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN1572 belongs to the majority class of normal typeIa supernovae.

  4. Against the Wind: Radio Light Curves of Type Ia Supernovae Interacting with Low-density Circumstellar Shells

    NASA Astrophysics Data System (ADS)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N.

    2016-06-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  5. Tycho Brahe's 1572 supernova as a standard type Ia as revealed by its light-echo spectrum.

    PubMed

    Krause, Oliver; Tanaka, Masaomi; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-12-01

    Type Ia supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a type Ia supernova in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of type Ia supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN 1572 belongs to the majority class of normal type Ia supernovae.

  6. THE DWARF STARBURST HOST GALAXY OF A TYPE Ia SUPERNOVA AT z = 1.55 FROM CANDELS

    SciTech Connect

    Frederiksen, Teddy F.; Hjorth, Jens; Maund, Justyn R.; Rodney, Steven A.; Riess, Adam G.; Dahlen, Tomas; Mobasher, Bahram

    2012-12-01

    We present VLT/X-shooter observations of a high-redshift, Type Ia supernova (SN Ia) host galaxy, discovered with HST/WFC3 as part of the CANDELS Supernova project. The galaxy exhibits strong emission lines of Ly{alpha}, [O II], H{beta}, [O III], and H{alpha} at z = 1.54992{sup +0.00008} {sub -0.00004}. From the emission-line fluxes and spectral energy distribution fitting of broadband photometry we rule out activity from an active galactic nucleus and characterize the host galaxy as a young, low-mass, metal-poor, starburst galaxy with low intrinsic extinction and high Ly{alpha} escape fraction. The host galaxy stands out in terms of the star formation, stellar mass, and metallicity compared to its lower redshift counterparts, mainly because of its high specific star formation rate. If valid for a larger sample of high-redshift SN Ia host galaxies, such changes in the host galaxy properties with redshift are of interest because of the potential impact on the use of SN Ia as standard candles in cosmology.

  7. Strong near-infrared carbon in the Type Ia supernova iPTF13ebh

    DOE PAGES

    Hsiao, E. Y.; Burns, C. R.; Contreras, C.; Höflich, P.; Sand, D.; Marion, G. H.; Phillips, M. M.; Stritzinger, M.; González-Gaitán, S.; Mason, R. E.; et al

    2015-05-22

    We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C I lines, and the C Iλ1.0693 μm line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C II counterparts were found, even though themore » optical spectroscopic time series began early and is densely cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR C I compared to the weaker optical C II appears to be general in SNe Ia. iPTF13ebh is a fast decliner with Δm15(B) = 1.79 ± 0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a “transitional” event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest that composition and density of the inner core are similar to that of 91bg-like events, and that it has a deep-reaching carbon burning layer that is not observed in more slowly declining SNe Ia. Furthermore, there is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the Si II λ0.6355 μm line, implying a long dark phase of ~4 days.« less

  8. Strong near-infrared carbon in the Type Ia supernova iPTF13ebh

    SciTech Connect

    Hsiao, E. Y.; Burns, C. R.; Contreras, C.; Höflich, P.; Sand, D.; Marion, G. H.; Phillips, M. M.; Stritzinger, M.; González-Gaitán, S.; Mason, R. E.; Folatelli, G.; Parent, E.; Gall, C.; Amanullah, R.; Anupama, G. C.; Arcavi, I.; Banerjee, D. P. K.; Beletsky, Y.; Blanc, G. A.; Bloom, J. S.; Brown, P. J.; Campillay, A.; Cao, Y.; De Cia, A.; Diamond, T.; Freedman, W. L.; Gonzalez, C.; Goobar, A.; Holmbo, S.; Howell, D. A.; Johansson, J.; Kasliwal, M. M.; Kirshner, R. P.; Krisciunas, K.; Kulkarni, S. R.; Maguire, K.; Milne, P. A.; Morrell, N.; Nugent, P. E.; Ofek, E. O.; Osip, D.; Palunas, P.; Perley, D. A.; Persson, S. E.; Piro, A. L.; Rabus, M.; Roth, M.; Schiefelbein, J. M.; Srivastav, S.; Sullivan, M.; Suntzeff, N. B.; Surace, J.; Woźniak, P. R.; Yaron, O.

    2015-05-22

    We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C I lines, and the C Iλ1.0693 μm line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C II counterparts were found, even though the optical spectroscopic time series began early and is densely cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR C I compared to the weaker optical C II appears to be general in SNe Ia. iPTF13ebh is a fast decliner with Δm15(B) = 1.79 ± 0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a “transitional” event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest that composition and density of the inner core are similar to that of 91bg-like events, and that it has a deep-reaching carbon burning layer that is not observed in more slowly declining SNe Ia. Furthermore, there is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the Si II λ0.6355 μm line, implying a long dark phase of ~4 days.

  9. A Search for New Candidate Super-Chandrasekhar-mass Type Ia Supernovae in the Nearby Supernova Factory Data Set

    NASA Astrophysics Data System (ADS)

    Scalzo, R.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.; Nearby Supernova Factory, The

    2012-09-01

    We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova Factory selected to be spectroscopic analogs of the candidate super-Chandrasekhar-mass events SN 2003fg and SN 2007if. Their spectra are characterized by hot, highly ionized photospheres near maximum light, for which SN 1991T supplies the best phase coverage among available close spectral templates. Like SN 2007if, these supernovae are overluminous (-19.5 < MV < -20) and the velocity of the Si II λ6355 absorption minimum is consistent with being constant in time from phases as early as a week before, and up to two weeks after, B-band maximum light. We interpret the velocity plateaus as evidence for a reverse-shock shell in the ejecta formed by interaction at early times with a compact envelope of surrounding material, as might be expected for SNe resulting from the mergers of two white dwarfs. We use the bolometric light curves and line velocity evolution of these SNe to estimate important parameters of the progenitor systems, including 56Ni mass, total progenitor mass, and masses of shells and surrounding carbon/oxygen envelopes. We find that the reconstructed total progenitor mass distribution of the events (including SN 2007if) is bounded from below by the Chandrasekhar mass, with SN 2007if being the most massive. We discuss the relationship of these events to the emerging class of super-Chandrasekhar-mass SNe Ia, estimate the relative rates, compare the mass distribution to that expected for double-degenerate SN Ia progenitors from population synthesis, and consider implications for future cosmological Hubble diagrams.

  10. A SEARCH FOR NEW CANDIDATE SUPER-CHANDRASEKHAR-MASS TYPE Ia SUPERNOVAE IN THE NEARBY SUPERNOVA FACTORY DATA SET

    SciTech Connect

    Scalzo, R.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.; Nugent, P.; Collaboration: Nearby Supernova Factory; and others

    2012-09-20

    We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova Factory selected to be spectroscopic analogs of the candidate super-Chandrasekhar-mass events SN 2003fg and SN 2007if. Their spectra are characterized by hot, highly ionized photospheres near maximum light, for which SN 1991T supplies the best phase coverage among available close spectral templates. Like SN 2007if, these supernovae are overluminous (-19.5 < M{sub V} < -20) and the velocity of the Si II {lambda}6355 absorption minimum is consistent with being constant in time from phases as early as a week before, and up to two weeks after, B-band maximum light. We interpret the velocity plateaus as evidence for a reverse-shock shell in the ejecta formed by interaction at early times with a compact envelope of surrounding material, as might be expected for SNe resulting from the mergers of two white dwarfs. We use the bolometric light curves and line velocity evolution of these SNe to estimate important parameters of the progenitor systems, including {sup 56}Ni mass, total progenitor mass, and masses of shells and surrounding carbon/oxygen envelopes. We find that the reconstructed total progenitor mass distribution of the events (including SN 2007if) is bounded from below by the Chandrasekhar mass, with SN 2007if being the most massive. We discuss the relationship of these events to the emerging class of super-Chandrasekhar-mass SNe Ia, estimate the relative rates, compare the mass distribution to that expected for double-degenerate SN Ia progenitors from population synthesis, and consider implications for future cosmological Hubble diagrams.

  11. Properties of extragalactic dust inferred from linear polarimetry of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Patat, F.; Taubenberger, S.; Cox, N. L. J.; Baade, D.; Clocchiatti, A.; Höflich, P.; Maund, J. R.; Reilly, E.; Spyromilio, J.; Wang, L.; Wheeler, J. C.; Zelaya, P.

    2015-05-01

    Aims: The aim of this paper is twofold: 1) to investigate the properties of extragalactic dust and compare them to what is seen in the Galaxy; 2) to address in an independent way the problem of the anomalous extinction curves reported for reddened Type Ia Supernovae (SN) in connection to the environments in which they explode. Methods: The properties of the dust are derived from the wavelength dependence of the continuum polarization observed in four reddened Type Ia SN: 1986G, 2006X, 2008fp, and 2014J. The method is based on the observed fact that Type Ia SN have a negligible intrinsic continuum polarization. This and their large luminosity makes them ideal tools to probe the dust properties in extragalactic environments. Results: All four objects are characterized by exceptionally low total-to-selective absorption ratios (RV) and display an anomalous interstellar polarization law, characterized by very blue polarization peaks. In all cases the polarization position angle is well aligned with the local spiral structure. While SN 1986G is compatible with the most extreme cases of interstellar polarization known in the Galaxy, SN 2006X, 2008fp, and 2014J show unprecedented behaviours. The observed deviations do not appear to be connected to selection effects related to the relatively large amounts of reddening characterizing the objects in the sample. Conclusions: The dust responsible for the polarization of these four SN is most likely of interstellar nature. The polarization properties can be interpreted in terms of a significantly enhanced abundance of small grains. The anomalous behaviour is apparently associated with the properties of the galactic environment in which the SN explode, rather than with the progenitor system from which they originate. For the extreme case of SN 2014J, we cannot exclude the contribution of light scattered by local material; however, the observed polarization properties require an ad hoc geometrical dust distribution. Based on

  12. The violent white dwarf merger scenario for the progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Liu, D.-D.; Wang, B.; Podsiadlowski, Ph.; Han, Z.

    2016-10-01

    Recent observations suggest that some Type Ia supernovae (SNe Ia) originate from the merging of two carbon-oxygen white dwarfs (CO WDs). Meanwhile, recent hydrodynamical simulations have indicated that the accretion-induced collapse may be avoided under certain conditions when double WDs merge violently. However, the properties of SNe Ia from this violent merger scenario are highly dependent on a particular mass-accretion stage, the so-called WD + He subgiant channel, during which the primary WD is able to increase its mass by accreting He-rich material from an He subgiant before the systems evolves into a double WD system. In this paper, we aim to study this particular evolutionary stage systematically and give the properties of violent WD mergers. By employing the Eggleton stellar evolution code, we followed a large number of binary calculations and obtained the regions in parameter space for producing violent mergers based on the WD + He subgiant channel. According to these simulations, we found that the primary WDs can increase their mass by ˜ 0.10-0.45 M⊙ during the mass-accretion stage. We then conducted a series of binary population synthesis calculations and found that the Galactic SN Ia birthrate from this channel is about 0.01-0.4 × 10-3 yr-1. This suggests that the violent WD mergers from this channel may only contribute to ˜0.3-10 per cent of all SNe Ia in our Galaxy. The delay times of violent WD mergers from this channel are ≥ 1.7 Gyr, contributing to the SNe Ia in old populations. We also found that the WD + He subgiant channel is the dominant way for producing violent WD mergers that may be able to eventually explode as SNe Ia.

  13. Constraining the role of novae as progenitors of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Soraisam, Monika D.; Gilfanov, Marat

    2015-11-01

    Context. With the progenitors of type Ia supernovae (SNe Ia) still eluding direct detections, various types of accreting white dwarfs (WDs) have been proposed as prospective candidates. One of the possibilities are WDs undergoing unstable nuclear burning on their surfaces. Although observations and theoretical modeling of classical novae generally suggest that more material is ejected during the explosion than is accreted, there is growing evidence that in certain accretion regimes of novae, appreciable mass accumulation by the WD in the course of unstable nuclear burning may be possible. Aims: We propose that statistics of novae in nearby galaxies may be a powerful tool to determine the role these systems play in producing SNe Ia. Methods: We used multicycle nova evolutionary models to compute the number and temporal distribution of novae that would be produced by a typical SN Ia progenitor before it reached the Chandrasekhar mass limit (Mch) and exploded, assuming that it experienced unstable nuclear burning during its entire accretion history. We then used the observed nova rate in M 31 to constrain the maximal contribution of the nova channel to the SN Ia rate in this galaxy. Results: The M 31 nova rate measured by the POINT-AGAPE survey is ≈ 65 yr-1. Assuming that all these novae will reach Mch, we estimate the maximal SN Ia rate novae may produce, which is ≲0.1-0.5 × 10-3 yr-1. This constrains the overall contribution of the nova channel to the SN Ia rate at ≲ 2-7%. However, if all POINT-AGAPE novae do eventually reach Mch, a significant population of fast novae (t2 ≲ 10 days) originating from the most massive WDs is expected, with a rate of ~200-300 yr-1, which is significantly higher than currently observed. We point out that statistics of such fast novae can provide powerful diagnostics of the contribution of the nova channel to the final stage of mass accumulation by the single-degenerate (SD) SN Ia progenitors. To explore the prospects of their

  14. Quantitative Spectroscopy of Distant Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Hook, I.; Howell, D. A.; Sullivan, M.; Perrett, K.; Conley, A.; Astier, P.; Basa, S.; Carlberg, R. G.; Guy, J.; Pain, R.; Pritchet, C. J.; Neill, James D.

    2007-08-01

    Quantitative analysis of 24 high-z (zmed = 0.81) Type Ia supernovae (SNe Ia) spectra observed at the Gemini Telescopes for the Supernova Legacy Survey (SNLS) is presented. This analysis includes equivalent width measurements of SNe Ia-specific absorption features with methods tailored to the reduced signal-to-noise and host galaxy contamination present in these distant spectra. The results from this analysis are compared to corresponding measurements of a large set of low-z SNe Ia from the literature. This comparison showed no significant difference (less than 2σ) between the spectroscopic features of the distant and nearby SNe; a result that supports the assumption that SNe Ia are not evolving with redshift. Additionally, a new correlation between SiII absorption (observed near peak luminosity) and SNe Ia peak magnitudes is presented.

  15. THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. III. CORRELATED PROPERTIES OF TYPE Ia SUPERNOVAE AND THEIR HOSTS AT 0.9 < z < 1.46

    SciTech Connect

    Meyers, J.; Barbary, K.; Fakhouri, H. K.; Goldhaber, G.; Aldering, G.; Faccioli, L.; Hsiao, E.; Barrientos, L. F.; Brodwin, M.; Dawson, K. S.; Deustua, S.; Fruchter, A. S.; Doi, M.; Ihara, Y.; Eisenhardt, P.; Gilbank, D. G.; Gladders, M. D.; Gonzalez, A. H.; Hattori, T.; Kashikawa, N.; Collaboration: Supernova Cosmology Project; and others

    2012-05-01

    Using the sample of Type Ia supernovae (SNe Ia) discovered by the Hubble Space Telescope (HST) Cluster Supernova Survey and augmented with HST-observed SNe Ia in the Great Observatories Origins Deep Survey (GOODS) fields, we search for correlations between the properties of SNe and their host galaxies at high redshift. We use galaxy color and quantitative morphology to determine the red sequence in 25 clusters and develop a model to distinguish passively evolving early-type galaxies from star-forming galaxies in both clusters and the field. With this approach, we identify 6 SN Ia hosts that are early-type cluster members and 11 SN Ia hosts that are early-type field galaxies. We confirm for the first time at z > 0.9 that SNe Ia hosted by early-type galaxies brighten and fade more quickly than SNe Ia hosted by late-type galaxies. We also show that the two samples of hosts produce SNe Ia with similar color distributions. The relatively simple spectral energy distributions expected for passive galaxies enable us to measure stellar masses of early-type SN hosts. In combination with stellar mass estimates of late-type GOODS SN hosts from Thomson and Chary, we investigate the correlation of host mass with Hubble residual observed at lower redshifts. Although the sample is small and the uncertainties are large, a hint of this relation is found at z > 0.9. By simultaneously fitting the average cluster galaxy formation history and dust content to the red-sequence scatters, we show that the reddening of early-type cluster SN hosts is likely E(B - V) {approx}< 0.06. The similarity of the field and cluster early-type host samples suggests that field early-type galaxies that lie on the red sequence may also be minimally affected by dust. Hence, the early-type-hosted SNe Ia studied here occupy a more favorable environment to use as well-characterized high-redshift standard candles than other SNe Ia.

  16. Constraints on the progenitor system of the type Ia supernova 2014J from pre-explosion Hubble space telescope imaging

    SciTech Connect

    Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E.; Cenko, S. Bradley; Schaefer, Gail

    2014-07-20

    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d ≈ 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T ≲ 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of R{sub V} and A{sub V} values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T < 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

  17. Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-Explosion Hubble Space Telescope Imaging

    NASA Technical Reports Server (NTRS)

    Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Cenko, S. Bradley; Prato, Lisa; Schaefer, Gail; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E.

    2014-01-01

    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d (is) approx. 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T (is) approximately 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of RV and AV values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T (is) less than 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

  18. Supernova 2014J at M82 - II. Direct analysis of a middle-class Type Ia supernova

    NASA Astrophysics Data System (ADS)

    Vallely, Patrick; Moreno-Raya, M. E.; Baron, E.; Ruiz-Lapuente, Pilar; Domínguez, I.; Galbany, Lluís; González Hernández, J. I.; Méndez, J.; Hamuy, M.; López-Sánchez, A. R.; Catalán, S.; Cooke, E.; Fariña, C.; Génova-Santos, R.; Karjalainen, R.; Lietzen, H.; McCormac, J.; Riddick, F.; Rubiño-Martín, J. A.; Skillen, I.; Tudor, V.; Vaduvescu, O.

    2016-08-01

    We analyse a time series of optical spectra of SN 2014J from almost two weeks prior to maximum to nearly four months after maximum. We perform our analysis using the SYNOW code, which is well suited to track the distribution of the ions with velocity in the ejecta. We show that almost all of the spectral features during the entire epoch can be identified with permitted transitions of the common ions found in normal supernovae (SNe) Ia in agreement with previous studies. We show that 2014J is a relatively normal SN Ia. At early times the spectral features are dominated by Si II, S II, Mg II, and Ca II. These ions persist to maximum light with the appearance of Na I and Mg I. At later times iron-group elements also appear, as expected in the stratified abundance model of the formation of normal Type Ia SNe. We do not find significant spectroscopic evidence for oxygen, until 100 d after maximum light. The +100 d identification of oxygen is tentative, and would imply significant mixing of unburned or only slight processed elements down to a velocity of 6000 kms-1. Our results are in relatively good agreement with other analyses in the infrared. We briefly compare SN 2011fe to SN 2014J and conclude that the differences could be due to different central densities at ignition or differences in the C/O ratio of the progenitors.

  19. Magnetic susceptibility of SnCr, SnMn, SnFe, SnCo and SnNi

    NASA Astrophysics Data System (ADS)

    Henger, U.; Korn, D.

    1984-11-01

    The initial ac susceptibility χ of vapour condensed Sn films with 3d transition metals is measured in situ. SnMn is a spin glass at concentrations up to 36 at% Mn. Spin glass behaviour in SnCr is only observed after annealing to temperatures between 220 and 300 K. This can be related to crystallization in the amorphous and disordered SnCr. SnFe and SnCo exhibit either temperature independent χ or χ below experimental detection. Above the percolation limit χ is getting large and temperature dependent. That is valid for Sn with 30 at% Fe or Co. In Sn films with 50 at% Ni the susceptibility is below the experimental limit.

  20. New approaches for modeling type Ia supernovae

    SciTech Connect

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-06-25

    Type Ia supernovae (SNe Ia) are the largest thermonuclearexplosions in the Universe. Their light output can be seen across greatstances and has led to the discovery that the expansion rate of theUniverse is accelerating. Despite the significance of SNe Ia, there arestill a large number of uncertainties in current theoretical models.Computational modeling offers the promise to help answer the outstandingquestions. However, even with today's supercomputers, such calculationsare extremely challenging because of the wide range of length and timescales. In this paper, we discuss several new algorithms for simulationsof SNe Ia and demonstrate some of their successes.

  1. SNe Ia as a cosmological probe

    NASA Astrophysics Data System (ADS)

    Meng, Xiangcun; Gao, Yan; Han, Zhanwen

    2015-09-01

    Type Ia supernovae (SNe Ia) luminosities can be corrected in order to render them useful as standard candles that are able to probe the expansion history of the universe. This technique was successfully applied to discover the present acceleration of the universe. As the number of SNe Ia observed at high redshift increases and analysis techniques are perfected, people aim to use this technique to probe the equation-of-state of the dark energy (EOSDE). Nevertheless, the nature of SNe Ia progenitors remains controversial and concerns persist about possible evolution effects that may be larger and harder to characterize than the more obvious statistical uncertainties.

  2. Core-collapse and Type Ia supernovae with the SKA

    NASA Astrophysics Data System (ADS)

    Perez-Torres, M.; Alberdi, A.; Beswick, R. J.; Lundqvist, P.; Herrero-Illana, R.; Romero-Cañizales, C.; Ryder, S.; della Valle, M.; Conway, J.; Marcaide, J. M.; Mattila, S.; Murphy, T.; Ros, E.

    2015-04-01

    Core-collapse SNe (CCSNe): Systematic searches of radio emission from CCSNe are still lacking, and only targeted searches of radio emission from just some of the optically discovered CCSNe in the local universe have been carried out. Optical searches miss a significant fraction of CCSNe due to dust obscuration; CCSN radio searches are thus more promising for yielding the complete, unobscured star-formation rates in the local universe. The SKA yields the possibility to piggyback for free in this area of research by carrying out commensal, wide-field, blind transient survey observations. SKA1-SUR should be able to discover several hundreds of CCSNe in just one year, compared to about a dozen CCSNe that the VLASS would be able to detect in one year, at most. SKA, with an expected sensitivity ten times that of SKA1, is expected to detect CCSNe in the local Universe by the thousands. Therefore, commensal SKA observations could easily result in an essentially complete census of all CCSNe in the local universe, thus yielding an accurate determination of the volumetric CCSN rate. Type Ia SNe: We advocate for the use of the SKA to search for the putative prompt (~first few days after the explosion) radio emission of any nearby type Ia SN, via target-of-opportunity observations. The huge improvement in sensitivity of the SKA with respect to its predecessors will allow to unambiguously discern which progenitor scenario (single-degenerate vs. double-degenerate) applies to them.

  3. Multiband photometric follow-up of ASASSN-13aw (SN 2013dr)

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.; Campbell, H. C.; Koposov, S.; Ulaczyk, K.; Damljanovic, G.; Vince, O.; Pavlovic, R.; Cvetkovic, Z.; Stojanovic, M.; Kolb, U.; Bochinski, J.; Burwitz, V.; Haswell, C.; Rodriguez, J.; Harding, J.; Busuttil, R.

    2013-08-01

    We report the result of an extensive photometric follow-up of ASASSN-13aw (ATEL#5183) aka SN 2013dr, classified as type Ia supernova (Tomasella et al., CBAT TOCP for PSN J17193026+4742046). The telescopes involved in the follow-up operated in the preparatory mode for the forthcoming Gaia Science Ale$ follow-up network.

  4. Mid-Infrared Signatures from Type Ia Supernovae Strongly Interacting with a Circumstellar Medium

    NASA Astrophysics Data System (ADS)

    Fox, Ori

    2015-10-01

    Type Ia supernovae (SNe Ia) are well-known for their use as precise cosmological distance indicators due to a standardizable peak luminosity resulting from a thermonuclear explosion. A growing subset of SNe Ia, however, show evidence for interaction with a dense circumstellar medium during the first year post-explosion, and sometimes longer (SNe Ia-CSM). The origin of this dense CSM is unknown and suggests either a) the less typical single-degenerate progenitor scenario must be considered or b) the exploding star was not a thermonuclear explosion of a white dwarf at all (i.e., core-collapse). Mid-infrared (IR) observations, in particular, are critical for tracing the density profile of dust (and hence gas) in the surrounding CSM. Yet no Spitzer light curve exists for this subclass within the first year post-expolosion. Here we propose a 'low-impact' (>8 weeks) ToO to obtain 3 epochs of Spitzer imaging of a SN Ia-CSM within 100 Mpc over 1 year post-explosion. The strength of this program is that it will be in conjunction with pre-approved multi-wavelength programs on HST/STIS/UV (GO 13649), Chandra/ASIS-S (Num: 17500672), the Keck/LRIS optical spectrograph (Num: U037LA), and the RATIR visible/infrared robotic imager. Requiring only 2.1 hours of observation total, this program will not only distinguish between the SN explosion mechanisms, but also trace CSM interaction, constrain the progenitor mass loss history, and identify late-time heating mechanisms of warm dust.

  5. Mid-Infrared Signatures from Type Ia Supernovae Strongly Interacting with a Circumstellar Medium

    NASA Astrophysics Data System (ADS)

    Fox, Ori

    2016-08-01

    Type Ia supernovae (SNe Ia) are well-known for their use as precise cosmological distance indicators due to a standardizable peak luminosity resulting from a thermonuclear explosion. A growing subset of SNe Ia, however, show evidence for interaction with a dense circumstellar medium during the first year post-explosion, and sometimes longer (SNe Ia-CSM). The origin of this dense CSM is unknown and suggests either a) the less typical single-degenerate progenitor scenario must be considered or b) the exploding star was not a thermonuclear explosion of a white dwarf at all (i.e., core-collapse). Mid-infrared (IR) observations, in particular, are critical for tracing the density profile of dust (and hence gas) in the surrounding CSM. Yet no Spitzer light curve exists for this subclass within the first year post-expolosion. Here we propose a 'low-impact' (>8 weeks) ToO to obtain 3 epochs of Spitzer imaging of a SN Ia-CSM within 100 Mpc over 1 year post-explosion. The strength of this program is that it will be in conjunction with pre-approved multi-wavelength programs on HST/STIS/UV (GO 13649), Chandra/ASIS-S (17500672), the Keck/LRIS optical spectrograph (U037LA), and the RATIR visible/infrared robotic imager. Requiring only 2.1 hours of observation total, this program will not only distinguish between the SN explosion mechanisms, but also trace CSM interaction, constrain the progenitor mass loss history, and identify late-time heating mechanisms of warm dust.

  6. Constraints on the explosion mechanism and progenitors of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Blondin, Stéphane; Hillier, D. John; Khokhlov, Alexei

    2014-06-01

    Observations of SN 2011fe at early times reveal an evolution analogous to a fireball model of constant colour. In contrast, our unmixed delayed detonations of Chandrasekhar-mass white dwarfs (DDC series) exhibit a faster brightening concomitant with a shift in colour to the blue. In this paper, we study the origin of these discrepancies. We find that strong chemical mixing largely resolves the photometric mismatch at early times, but it leads to an enhanced line broadening that contrasts, for example, with the markedly narrow Si II 6355 Å line of SN 2011fe. We also explore an alternative configuration with pulsational-delayed detonations (PDDEL model series). Because of the pulsation, PDDEL models retain more unburnt carbon, have little mass at high velocity, and have a much hotter outer ejecta after the explosion. The pulsation does not influence the inner ejecta, so PDDEL and DDC models exhibit similar radiative properties beyond maximum. However, at early times, PDDEL models show bluer optical colours and a higher luminosity, even for weak mixing. Their early-time radiation is derived primarily from the initial shock-deposited energy in the outer ejecta rather than radioactive-decay heating. Furthermore, PDDEL models show short-lived C II lines, reminiscent of SN 2013dy. They typically exhibit lines that are weaker, narrower, and of near-constant width, reminiscent of SN 2011fe. In addition to multidimensional effects, varying configurations for such `pulsations' offer a source of spectral diversity amongst Type Ia supernovae (SNe Ia). PDDEL and DDC models also provide one explanation for low- and high-velocity-gradient SNe Ia.

  7. The Type Ia Supernova Rate at z~0.5 from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Neill, J. D.; Sullivan, M.; Balam, D.; Pritchet, C. J.; Howell, D. A.; Perrett, K.; Astier, P.; Aubourg, E.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Pain, R.; Palanque-Delabrouille, N.; Regnault, N.; Rich, J.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Ellis, R. S.; Filiol, M.; Gonçalves, A. C.; Hardin, D.; Kowalski, M.; Lidman, C.; Lusset, V.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Schlegel, D.; Tao, C.

    2006-09-01

    We present a measurement of the distant Type Ia supernova (SN Ia) rate derived from the first 2 yr of the Canada-France-Hawaii Telescope Supernova Legacy Survey. We observed four 1deg×1deg fields with a typical temporal frequency of <Δt>~4 observer-frame days over time spans of 158-211 days per season for each field, with breaks during the full Moon. We used 8-10 m class telescopes for spectroscopic follow-up to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified SNe Ia in the redshift range 0.2SN Ia rate of rV(=0.47)=[0.42+0.13-0.09(syst.)+/-0.06(stat.)×10-4 yr-1 Mpc3, assuming h=0.7, Ωm=0.3, and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of rL(=0.47)=0.154+0.048-0.033(syst.)+0.039-0.031(stat.) SN units. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star formation history of 1 SN Ia per 103 Msolar of stars formed. Our rate and other rates from surveys using spectroscopic sample confirmation display only a modest evolution out to z=0.55. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. This work is also based on observations obtained at the European Southern Observatory using the Very Large Telescope on the Cerro Paranal (ESO Large Program 171.A-0486), and on observations (programs GN-2004A-Q-19, GS-2004A-Q-11

  8. VERY LATE PHOTOMETRY OF SN 2011fe

    SciTech Connect

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of {sup 56}Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  9. Very Late Photometry of SN 2011fe

    NASA Astrophysics Data System (ADS)

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of 56Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  10. Genetics Home Reference: hereditary sensory neuropathy type IA

    MedlinePlus

    ... Conditions hereditary sensory neuropathy type IA hereditary sensory neuropathy type IA Enable Javascript to view the expand/ ... PDF Open All Close All Description Hereditary sensory neuropathy type IA is a condition characterized by nerve ...

  11. THE RISE OF SN 2014J IN THE NEARBY GALAXY M82

    SciTech Connect

    Goobar, A.; Johansson, J.; Amanullah, R.; Ferretti, R.; Cao, Y.; Perley, D. A.; Tendulkar, S. P.; Kasliwal, M. M.; Nugent, P. E.; Harris, C.; Gal-Yam, A.; Ofek, E. O.; Dennefeld, M.; Valenti, S.; Arcavi, I.; Banerjee, D. P. K.; Venkataraman, V.; Joshi, V.; Ashok, N. M.; Cenko, S. B.; and others

    2014-03-20

    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, R{sub V} ≲ 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.

  12. Detection of a Light Echo from the Otherwise Normal SN 2007af

    NASA Astrophysics Data System (ADS)

    Drozdov, D.; Leising, M. D.; Milne, P. A.; Pearcy, J.; Riess, A. G.; Macri, L. M.; Bryngelson, G. L.; Garnavich, P. M.

    2015-05-01

    We present the discovery of a light echo from SN 2007af, a normal Type Ia supernova (SN Ia) in NGC 5584. Hubble Space Telescope images taken three years post explosion reveal two separate echoes: an outer echo and an extended central region, which we propose to be an inner echo for which details are unresolved. Multiple images were obtained in the F160W, F350LP, F555W, and F814W using the Wide Field Camera 3. If the outer echo is produced by an interstellar dust sheet perpendicular to the line of sight, it is located ∼800 pc in front of the SN. The dust for the inner echo is 0.45 pc \\lt d\\lt 90 pc away from the SN. The inner echo color is consistent with typical interstellar dust wavelength-dependent scattering cross-sections, while the outer echo is redder than predicted. Both dust sheets, if in the foreground, are optically thin for scattering, and the outer echo sheet thickness is consistent with the inferred extinction from peak brightness. Whether the inner echo is from interstellar or circumstellar dust is ambiguous. Overall, the echo characteristics are quite similar to previously observed SN Ia echoes.

  13. Improved Constraints on Type Ia Supernova Host Galaxy Properties using Multi-Wavelength Photometry and their Correlations with Supernova Properties

    SciTech Connect

    Gupta, Ravi R.; D'Andrea, Chris B.; Sako, Masao; Conroy, Charlie; Smith, Mathew; Bassett, Bruce; Frieman, Joshua A.; Garnavich, Peter M.; Jha, Saurabh W.; Kessler, Richard; Lampeitl, Hubert; /Portsmouth U., ICG /Fermilab

    2011-07-01

    We improve estimates of the stellar mass and mass-weighted average age of Type Ia supernova (SN Ia) host galaxies by combining UV and near-IR photometry with optical photometry in our analysis. Using 206 SNe Ia drawn from the full three-year Sloan Digital Sky Survey (SDSS-II) Supernova Survey (median redshift of z {approx} 0.2) and multi-wavelength host-galaxy photometry from SDSS, the Galaxy Evolution Explorer, and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we present evidence of a correlation (1.9{sigma} confidence level) between the residuals of SNe Ia about the best-fit Hubble relation and the mass-weighted average age of their host galaxies. The trend is such that older galaxies host SNe Ia that are brighter than average after standard light-curve corrections are made. We also confirm, at the 3.0{sigma} level, the trend seen by previous studies that more massive galaxies often host brighter SNe Ia after light-curve correction.

  14. Large cell lymphoma stage IA/IAE.

    PubMed

    Nussbaum, H; Koo, C; Kagan, A R; Rao, A; Ryoo, M C

    1991-06-01

    Fifty-two patients with large cell lymphoma stage IA/IAE were retrospectively reviewed for the purpose of evaluation of treatment methods. All pathology slides were reviewed by one pathologist with a special interest in lymphoma. There were 24 patients at stage IA and 28 at stage IAE. Twenty-six patients were treated with radiation alone (10 IA, 16 IAE) and 26 patients were treated with radiation therapy and chemotherapy (13 IA, 13 IAE). Patients treated with radiation therapy alone and those with combined modality therapy (CMT) have similar survival curves with p values greater than 0.05. Recurrence patterns are similar for either method of treatment. While the majority of the literature recommends CMT for large cell lymphoma, our study of 52 patients reveals no difference in survival or recurrence patterns for these patients by either method of treatment. We recommend radiation therapy alone for stage IA/IAE large cell lymphoma, with chemotherapy held in reserve for failure.

  15. Radiogenic p-isotopes from type Ia supernova, nuclear physics uncertainties, and galactic chemical evolution compared with values in primitive meteorites

    SciTech Connect

    Travaglio, C.; Gallino, R.; Rauscher, T.; Dauphas, N.; Röpke, F. K.; Hillebrandt, W. E-mail: claudia.travaglio@b2fh.org

    2014-11-10

    The nucleosynthesis of proton-rich isotopes is calculated for multi-dimensional Chandrasekhar-mass models of Type Ia supernovae (SNe Ia) with different metallicities. The predicted abundances of the short-lived radioactive isotopes {sup 92}Nb, {sup 97,} {sup 98}Tc, and {sup 146}Sm are given in this framework. The abundance seeds are obtained by calculating s-process nucleosynthesis in the material accreted onto a carbon-oxygen white dwarf from a binary companion. A fine grid of s-seeds at different metallicities and {sup 13}C-pocket efficiencies is considered. A galactic chemical evolution model is used to predict the contribution of SN Ia to the solar system p-nuclei composition measured in meteorites. Nuclear physics uncertainties are critical to determine the role of SNe Ia in the production of {sup 92}Nb and {sup 146}Sm. We find that, if standard Chandrasekhar-mass SNe Ia are at least 50% of all SN Ia, they are strong candidates for reproducing the radiogenic p-process signature observed in meteorites.

  16. Radiogenic p-isotopes from Type Ia Supernova, Nuclear Physics Uncertainties, and Galactic Chemical Evolution Compared with Values in Primitive Meteorites

    NASA Astrophysics Data System (ADS)

    Travaglio, C.; Gallino, R.; Rauscher, T.; Dauphas, N.; Röpke, F. K.; Hillebrandt, W.

    2014-11-01

    The nucleosynthesis of proton-rich isotopes is calculated for multi-dimensional Chandrasekhar-mass models of Type Ia supernovae (SNe Ia) with different metallicities. The predicted abundances of the short-lived radioactive isotopes 92Nb, 97, 98Tc, and 146Sm are given in this framework. The abundance seeds are obtained by calculating s-process nucleosynthesis in the material accreted onto a carbon-oxygen white dwarf from a binary companion. A fine grid of s-seeds at different metallicities and 13C-pocket efficiencies is considered. A galactic chemical evolution model is used to predict the contribution of SN Ia to the solar system p-nuclei composition measured in meteorites. Nuclear physics uncertainties are critical to determine the role of SNe Ia in the production of 92Nb and 146Sm. We find that, if standard Chandrasekhar-mass SNe Ia are at least 50% of all SN Ia, they are strong candidates for reproducing the radiogenic p-process signature observed in meteorites.

  17. HEAD-ON COLLISIONS OF WHITE DWARFS IN TRIPLE SYSTEMS COULD EXPLAIN TYPE Ia SUPERNOVAE

    SciTech Connect

    Kushnir, Doron; Katz, Boaz; Dong, Subo; Fernández, Rodrigo; Livne, Eli

    2013-12-01

    Type Ia supernovae (SNe Ia), thermonuclear explosions of carbon-oxygen white dwarfs (CO-WDs), are currently the best cosmological ''standard candles'', but the triggering mechanism of the explosion is unknown. It was recently shown that the rate of head-on collisions of typical field CO-WDs in triple systems may be comparable to the SNe Ia rate. Here we provide evidence supporting a scenario in which the majority of SNe Ia are the result of such head-on collisions of CO-WDs. In this case, the nuclear detonation is due to a well understood shock ignition, devoid of commonly introduced free parameters such as the deflagration velocity or transition to detonation criteria. By using two-dimensional hydrodynamical simulations with a fully resolved ignition process, we show that zero-impact-parameter collisions of typical CO-WDs with masses 0.5-1 M {sub ☉} result in explosions that synthesize {sup 56}Ni masses in the range of ∼0.1-1 M {sub ☉}, spanning the wide distribution of yields observed for the majority of SNe Ia. All collision models yield the same late-time (≳ 60 days since explosion) bolometric light curve when normalized by {sup 56}Ni masses (to better than 30%), in agreement with observations. The calculated widths of the {sup 56}Ni-mass-weighted line-of-sight velocity distributions are correlated with the calculated {sup 56}Ni yield, agreeing with the observed correlation. The strong correlation, shown here for the first time, between {sup 56}Ni yield and total mass of the colliding CO-WDs (insensitive to their mass ratio), is suggestive as the source for the continuous distribution of observed SN Ia features, possibly including the Philips relation.

  18. Head-on Collisions of White Dwarfs in Triple Systems Could Explain Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Kushnir, Doron; Katz, Boaz; Dong, Subo; Livne, Eli; Fernández, Rodrigo

    2013-12-01

    Type Ia supernovae (SNe Ia), thermonuclear explosions of carbon-oxygen white dwarfs (CO-WDs), are currently the best cosmological "standard candles," but the triggering mechanism of the explosion is unknown. It was recently shown that the rate of head-on collisions of typical field CO-WDs in triple systems may be comparable to the SNe Ia rate. Here we provide evidence supporting a scenario in which the majority of SNe Ia are the result of such head-on collisions of CO-WDs. In this case, the nuclear detonation is due to a well understood shock ignition, devoid of commonly introduced free parameters such as the deflagration velocity or transition to detonation criteria. By using two-dimensional hydrodynamical simulations with a fully resolved ignition process, we show that zero-impact-parameter collisions of typical CO-WDs with masses 0.5-1 M ⊙ result in explosions that synthesize 56Ni masses in the range of ~0.1-1 M ⊙, spanning the wide distribution of yields observed for the majority of SNe Ia. All collision models yield the same late-time (gsim 60 days since explosion) bolometric light curve when normalized by 56Ni masses (to better than 30%), in agreement with observations. The calculated widths of the 56Ni-mass-weighted line-of-sight velocity distributions are correlated with the calculated 56Ni yield, agreeing with the observed correlation. The strong correlation, shown here for the first time, between 56Ni yield and total mass of the colliding CO-WDs (insensitive to their mass ratio), is suggestive as the source for the continuous distribution of observed SN Ia features, possibly including the Philips relation.

  19. Berkeley Supernova Ia Program - II. Initial analysis of spectra obtained near maximum brightness

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Kong, Jason J.; Filippenko, Alexei V.

    2012-09-01

    In this second paper in a series, we present measurements of spectral features of 432 low-redshift (z < 0.1) optical spectra of 261 Type Ia supernovae (SNe Ia) within 20 d of maximum brightness. The data were obtained from 1989 to the end of 2008 as part of the Berkeley Supernova Ia Program (BSNIP) and are presented in BSNIP I by Silverman et al. We describe in detail our method of automated, robust spectral feature definition and measurement which expands upon similar previous studies. Using this procedure, we attempt to measure expansion velocities, pseudo-equivalent widths (pEWs), spectral feature depths and fluxes at the centre and endpoints of each of nine major spectral feature complexes. We investigate how velocity and pEW evolve with time and how they correlate with each other. Various spectral classification schemes are employed and quantitative spectral differences among the subclasses are investigated. Several ratios of pEW values are calculated and studied. The so-called Si II ratio, often used as a luminosity indicator, is found to be well correlated with the so-called SiFe ratio and anticorrelated with the analogous 'SSi ratio', confirming the results of previous studies. Furthermore, SNe Ia that show strong evidence for interaction with circumstellar material or an aspherical explosion are found to have the largest near-maximum expansion velocities and pEWs, possibly linking extreme values of spectral observables with specific progenitor or explosion scenarios. We find that purely spectroscopic classification schemes are useful in identifying the most peculiar SNe Ia. However, in almost all spectral parameters investigated, the full sample of objects spans a nearly continuous range of values. Comparisons to previously published theoretical models of SNe Ia are made and we conclude with a brief discussion of how the measurements performed herein and the possible correlations presented will be important for future SN surveys.

  20. Time-varying sodium absorption in the Type Ia supernova 2013gh

    NASA Astrophysics Data System (ADS)

    Ferretti, R.; Amanullah, R.; Goobar, A.; Johansson, J.; Vreeswijk, P. M.; Butler, R. P.; Cao, Y.; Cenko, S. B.; Doran, G.; Filippenko, A. V.; Freeland, E.; Hosseinzadeh, G.; Howell, D. A.; Lundqvist, P.; Mattila, S.; Nordin, J.; Nugent, P. E.; Petrushevska, T.; Valenti, S.; Vogt, S.; Wozniak, P.

    2016-07-01

    Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. Aims: To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all of which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light. Methods: We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorption-line variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results: Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of Na I gas at R ≈ 1019 cm from the explosion. Conclusions: Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those distances. Full Tables 2 and 3 are only

  1. Light Echoes and Late-Time Emissions of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Drozdov, Dina

    2016-05-01

    Type Ia supernovae have many applications in astronomy, yet with fundamental properties still not fully understood, new methods for investigating the environment of a supernova need to be developed. A light echo is produced from the scattering of light from a bright source and can be used to analyze the dust in the vicinity of the supernova and learn invaluable information about the source. These techniques can put constraints on explosion and progenitor models. Although light echo detections from Type Ia supernovae are rare, with only seven total extragalactic detections, this could be due to the lack of thorough late-epoch monitoring. Since key information is determined from even a single light echo detection, light echo searches should be undertaken in the future to supplement our understanding of supernovae. As part of our collaborative campaign for studying the emission of supernovae at late epochs, we have added two light echoes to a small sample size of Type Ia supernova light echo detections: SN 2009ig in NGC 1015 and a dual echo from SN 2007af in NGC 5584. Both echoes were observed with the Hubble Space Telescope and allow for the most detailed images of Type Ia supernova light echoes to date. Three filters (F555W, F814W, and F350LP) captured the echoes obtained with the Wide Field Camera 3, and since both host galaxies were imaged as part of the same observing program, these cases will be the best comparable light echo pairs. We also further investigate the light echoes from SN 2006X in NGC 4321 and SN 1998bu in NGC 3368 from Hubble Space Telescope archival images. Analyses performed on the images gives crucial insight into the dusty environment of the host galaxy and the surroundings of the supernova. The outer echo from SN 2007af was created from an interstellar dust sheet located ~800 pc in front of the supernova, while the inner echo could be from interstellar or circumstellar origin. A circumstellar light echo could imply a single degenerate

  2. The VLT Measures the Shape of a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    2003-08-01

    1448 and SN 2001el (DSS and NTT/EMMI). PR Photo 24b/03 : Optical spectrum of SN 2001el and fractional polarisation (VLT/FORS) Supernova explosions and cosmic distances During Type Ia supernova events, remnants of stars with an initial mass of up to a few times that of the Sun (so-called "white dwarf stars") explode, leaving nothing behind but a rapidly expanding cloud of "stardust". Type Ia supernovae are apparently quite similar to one another. This provides them a very useful role as "standard candles" that can be used to measure cosmic distances. Their peak brightness rivals that of their parent galaxy, hence qualifying them as prime cosmic yardsticks. Astronomers have exploited this fortunate circumstance to study the expansion history of our Universe. They recently arrived at the fundamental conclusion that the Universe is expanding at an accelerating rate, cf. ESO PR 21/98, December 1998 (see also the Supernova Acceleration Probe web page). The explosion of a white dwarf star In the most widely accepted models of Type Ia supernovae the pre-explosion white dwarf star orbits a solar-like companion star, completing a revolution every few hours. Due to the close interaction, the companion star continuously loses mass, part of which is picked up (in astronomical terminology: "accreted") by the white dwarf. A white dwarf represents the penultimate stage of a solar-type star. The nuclear reactor in its core has run out of fuel a long time ago and is now inactive. However, at some point the mounting weight of the accumulating material will have increased the pressure inside the white dwarf so much that the nuclear ashes in there will ignite and start burning into even heavier elements. This process very quickly becomes uncontrolled and the entire star is blown to pieces in a dramatic event. An extremely hot fireball is seen that often outshines the host galaxy. The shape of the explosion Although all supernovae of Type Ia have quite similar properties, it has never been

  3. THE 1999aa-LIKE TYPE Ia SUPERNOVA IPTF14BDN IN THE ULTRAVIOLET AND OPTICAL

    SciTech Connect

    Smitka, Michael T.; Brown, Peter J.; Suntzeff, Nicholas B.; Zhang, Jujia; Zhai, Qian; Wang, Xiaofeng; Mo, Jun; Zhang, Tianmeng

    2015-11-01

    We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope and constitute the first UV spectral series of a 1999aa-like SN. From the photometry, we measure Δm{sub 15}(B) = 0.84 ± 0.05 mag and blue UV colors at epochs earlier than −5 days. The spectra show that the early-time blue colors are the result of less absorption between 2800−3200 Å than is present in normal SNe Ia. Using model spectra fits of the data at −10 and +10 days, we identify the origin of this spectral feature to be a temperature effect in which doubly ionized iron group elements create an opacity “window.” We determine that the detection of high temperatures and large quantities of iron group elements at early epochs imply the mixing of a high Ni mass into the outer layers of the SN ejecta. We also identify the source of the I-band secondary maximum in iPTF14bdn to be the decay of Fe iii to Fe ii, as is seen in normal SNe Ia.

  4. An asymptotic-giant-branch star in the progenitor system of a type Ia supernova.

    PubMed

    Hamuy, Mario; Phillips, M M; Suntzeff, Nicholas B; Maza, José; González, L E; Roth, Miguel; Krisciunas, Kevin; Morrell, Nidia; Green, E M; Persson, S E; McCarthy, P J

    2003-08-01

    Stars that explode as supernovae come in two main classes. A type Ia supernova is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in its spectrum; this class of supernova is thought to produce the majority of iron-peak elements in the Universe. They are also used as precise 'standard candles' to measure the distances to galaxies. While there is general agreement that a type Ia supernova is produced by an exploding white dwarf star, no progenitor system has ever been directly observed. Significant effort has gone into searching for circumstellar material to help discriminate between the possible kinds of progenitor systems, but no such material has hitherto been found associated with a type Ia supernova. Here we report the presence of strong hydrogen emission associated with the type Ia supernova SN2002ic, indicating the presence of large amounts of circumstellar material. We infer from this that the progenitor system contained a massive asymptotic-giant-branch star that lost several solar masses of hydrogen-rich gas before the supernova explosion. PMID:12904786

  5. On Measuring the Metallicity of a Type Ia Supernova’s Progenitor

    NASA Astrophysics Data System (ADS)

    Miles, Broxton J.; van Rossum, Daniel R.; Townsley, Dean M.; Timmes, F. X.; Jackson, Aaron P.; Calder, Alan C.; Brown, Edward F.

    2016-06-01

    In Type Ia Supernovae (SNe Ia) the relative abundances of chemical elements are affected by the neutron excess in the composition of the progenitor white dwarf. Since these products leave signatures in the spectra near maximum light, spectral features may be used to constrain the composition of the progenitor. We calculate the nucleosynthetic yields for three SN Ia simulations, assuming single degenerate, Chandrasekhar-mass progenitors, for a wide range of progenitor metallicities, and calculate synthetic light curves and spectra to explore correlations between progenitor metallicity and the strength of spectral features. We use two two-dimensional simulations of the deflagration-detonation-transition scenario with different 56Ni yields and the W7 simulation to control for differences between explosion models and total yields. While the overall yields of intermediate-mass elements (16 < A ≤slant 40) differ between the three cases, trends in the yields are similar. With increasing metallicity, 28Si yields remain nearly constant, 40Ca yields decline, and Ti and 54Fe yields increase. In the synthetic spectra, we identify two features at 30 days post-explosion that appear to deepen with progenitor metallicity: a Ti feature around 4200 Å and an Fe feature around 5200 Å. In all three simulations, their pseudo equivalent widths show a systematic trend with progenitor metallicity. This suggests that these two features may allow for differentiation among progenitor metallicities of observed SNe Ia and potentially help to reduce the intrinsic Hubble scatter.

  6. An asymptotic-giant-branch star in the progenitor system of a type Ia supernova.

    PubMed

    Hamuy, Mario; Phillips, M M; Suntzeff, Nicholas B; Maza, José; González, L E; Roth, Miguel; Krisciunas, Kevin; Morrell, Nidia; Green, E M; Persson, S E; McCarthy, P J

    2003-08-01

    Stars that explode as supernovae come in two main classes. A type Ia supernova is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in its spectrum; this class of supernova is thought to produce the majority of iron-peak elements in the Universe. They are also used as precise 'standard candles' to measure the distances to galaxies. While there is general agreement that a type Ia supernova is produced by an exploding white dwarf star, no progenitor system has ever been directly observed. Significant effort has gone into searching for circumstellar material to help discriminate between the possible kinds of progenitor systems, but no such material has hitherto been found associated with a type Ia supernova. Here we report the presence of strong hydrogen emission associated with the type Ia supernova SN2002ic, indicating the presence of large amounts of circumstellar material. We infer from this that the progenitor system contained a massive asymptotic-giant-branch star that lost several solar masses of hydrogen-rich gas before the supernova explosion.

  7. On Measuring the Metallicity of a Type Ia Supernova’s Progenitor

    NASA Astrophysics Data System (ADS)

    Miles, Broxton J.; van Rossum, Daniel R.; Townsley, Dean M.; Timmes, F. X.; Jackson, Aaron P.; Calder, Alan C.; Brown, Edward F.

    2016-06-01

    In Type Ia Supernovae (SNe Ia) the relative abundances of chemical elements are affected by the neutron excess in the composition of the progenitor white dwarf. Since these products leave signatures in the spectra near maximum light, spectral features may be used to constrain the composition of the progenitor. We calculate the nucleosynthetic yields for three SN Ia simulations, assuming single degenerate, Chandrasekhar-mass progenitors, for a wide range of progenitor metallicities, and calculate synthetic light curves and spectra to explore correlations between progenitor metallicity and the strength of spectral features. We use two two-dimensional simulations of the deflagration–detonation–transition scenario with different 56Ni yields and the W7 simulation to control for differences between explosion models and total yields. While the overall yields of intermediate-mass elements (16 < A ≤slant 40) differ between the three cases, trends in the yields are similar. With increasing metallicity, 28Si yields remain nearly constant, 40Ca yields decline, and Ti and 54Fe yields increase. In the synthetic spectra, we identify two features at 30 days post-explosion that appear to deepen with progenitor metallicity: a Ti feature around 4200 Å and an Fe feature around 5200 Å. In all three simulations, their pseudo equivalent widths show a systematic trend with progenitor metallicity. This suggests that these two features may allow for differentiation among progenitor metallicities of observed SNe Ia and potentially help to reduce the intrinsic Hubble scatter.

  8. FLOYDS Classification of MASTER OT J164244.87+272054.3 as a Type Ia Supernova Near Peak

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Arcavi, I.; Howell, D. A.; McCully, C.; Valenti, S.

    2016-05-01

    We obtained a spectrum of MASTER OT J164244.87+272054.3 (ATel #9022) on 2016 May 6.6 UT with the robotic FLOYDS instrument mounted on the LCOGT 2-meter telescope in Siding Spring, Australia. Using SNID (Blondin & Tonry 2007, ApJ, 666, 1024), we find a good fit to the normal Type Ia SN 1990N 2 days after maximum light at redshift z=0.108.

  9. The progenitors of supernovae Type Ia

    NASA Astrophysics Data System (ADS)

    Toonen, Silvia

    2014-09-01

    Despite the significance of Type Ia supernovae (SNeIa) in many fields in astrophysics, SNeIa lack a theoretical explanation. SNeIa are generally thought to be thermonuclear explosions of carbon/oxygen (CO) white dwarfs (WDs). The canonical scenarios involve white dwarfs reaching the Chandrasekhar mass, either by accretion from a non-degenerate companion (single-degenerate channel, SD) or by a merger of two CO WDs (double-degenerate channel, DD). The study of SNeIa progenitors is a very active field of research for binary population synthesis (BPS) studies. The strength of the BPS approach is to study the effect of uncertainties in binary evolution on the macroscopic properties of a binary population, in order to constrain binary evolutionary processes. I will discuss the expected SNeIa rate from the BPS approach and the uncertainties in their progenitor evolution, and compare with current observations. I will also discuss the results of the POPCORN project in which four BPS codes were compared to better understand the differences in the predicted SNeIa rate of the SD channel. The goal of this project is to investigate whether differences in the simulated populations are due to numerical effects or whether they can be explained by differences in the input physics. I will show which assumptions in BPS codes affect the results most and hence should be studied in more detail.

  10. No surviving evolved companions of the progenitor of SN 1006

    NASA Astrophysics Data System (ADS)

    González Hernández, Jonay I.; Ruiz-Lapuente, Pilar; Tabernero, Hugo M.; Montes, David; Canal, Ramon; Méndez, Javier; Bedin, Luigi R.

    2012-09-01

    Type Ia supernovae are thought to occur when a white dwarf made of carbon and oxygen accretes sufficient mass to trigger a thermonuclear explosion. The accretion could be slow, from an unevolved (main-sequence) or evolved (subgiant or giant) star (the single-degenerate channel), or rapid, as the primary star breaks up a smaller orbiting white dwarf (the double-degenerate channel). A companion star will survive the explosion only in the single-degenerate channel. Both channels might contribute to the production of type Ia supernovae, but the relative proportions of their contributions remain a fundamental puzzle in astronomy. Previous searches for remnant companions have revealed one possible case for SN 1572 (refs 8, 9), although that has been questioned. More recently, observations have restricted surviving companions to be small, main-sequence stars, ruling out giant companions but still allowing the single-degenerate channel. Here we report the results of a search for surviving companions of the progenitor of SN 1006 (ref. 14). None of the stars within 4 arc minutes of the apparent site of the explosion is associated with the supernova remnant, and we can firmly exclude all giant and subgiant stars from being companions of the progenitor. In combination with previous results, our findings indicate that fewer than 20 per cent of type Ia supernovae occur through the single-degenerate channel.

  11. High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios

    NASA Astrophysics Data System (ADS)

    Taubenberger, S.; Benetti, S.; Childress, M.; Pakmor, R.; Hachinger, S.; Mazzali, P. A.; Stanishev, V.; Elias-Rosa, N.; Agnoletto, I.; Bufano, F.; Ergon, M.; Harutyunyan, A.; Inserra, C.; Kankare, E.; Kromer, M.; Navasardyan, H.; Nicolas, J.; Pastorello, A.; Prosperi, E.; Salgado, F.; Sollerman, J.; Stritzinger, M.; Turatto, M.; Valenti, S.; Hillebrandt, W.

    2011-04-01

    Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s-1). Its light curves decline slowly over half a year after maximum light [Δm15(B)true= 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after ˜200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C II lines are present until ˜2 weeks past maximum, which is unprecedented in thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ˜1.8 M⊙ of 56Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ˜2.8 M⊙, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I? SNe to a core-collapse origin of the explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN

  12. CONSTRAINING THE SPIN-DOWN TIMESCALE OF THE WHITE DWARF PROGENITORS OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Meng, Xiangcun; Podsiadlowski, Philipp

    2013-12-01

    Justham and Di Stefano et al. proposed that the white dwarf progenitor of a Type Ia supernova (SN Ia) may have to spin down before it can explode. As the white dwarf spin-down timescale is not well known theoretically, here we try to constrain it empirically (within the framework of this spin-down model) for progenitor systems that contain a giant donor and for which circumbinary material has been detected after the explosion: we obtain an upper limit of a few 10{sup 7}yr. Based on the study of Di Stefano and Kilic, this means that it is too early to rule out the existence of a surviving companion in SNR 0509–67.5.

  13. Optical Identification of Cepheids in 19 Host Galaxies of Type Ia Supernovae and NGC 4258 with the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Hoffmann, Samantha L.; Macri, Lucas M.; Riess, Adam G.; Yuan, Wenlong; Casertano, Stefano; Foley, Ryan J.; Filippenko, Alexei V.; Tucker, Brad E.; Chornock, Ryan; Silverman, Jeffrey M.; Welch, Douglas L.; Goobar, Ariel; Amanullah, Rahman

    2016-10-01

    We present results of an optical search conducted as part of the SH0ES project (Supernovae and H0 for the Equation of State of dark energy) for Cepheid variable stars using the Hubble Space Telescope (HST) in 19 hosts of Type Ia supernovae (SNe Ia) and the maser-host galaxy NGC 4258. The targets include nine newly imaged SN Ia hosts using a novel strategy based on a long-pass filter that minimizes the number of HST orbits required to detect and accurately determine Cepheid properties. We carried out a homogeneous reduction and analysis of all observations, including new universal variability searches in all SN Ia hosts, which yielded a total of 2200 variables with well-defined selection criteria, the largest such sample identified outside the Local Group. These objects are used in a companion paper to determine the local value of H0 with a total uncertainty of 2.4%. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  14. Progenitor's Signatures in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.

    2013-01-01

    The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisting of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

  15. The rate of Type Ia supernovae at z ~ 0.2 from SDSS-I overlapping fields

    NASA Astrophysics Data System (ADS)

    Horesh, A.; Poznanski, D.; Ofek, E. O.; Maoz, D.

    2008-10-01

    In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z = 0.2. Our archival search, in ~5 per cent of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al., and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe. Accounting for the detection efficiency of the survey and for host extinction, this implies a Type Ia SN rate of rIa = (14.0+2.5+1.4-2.5-1.1 +/- 2.5) × 10-14h270yr-1L-1solar,g, where the errors are Poisson error, systematic detection efficiency error and systematic classification error, respectively. The volumetric rate is RIa = (1.89+0.42+0.18-0.34-0.15 +/- 0.42) × 10-5yr-1h370Mpc-3. Our measurement is consistent with other rate measurements at low redshift. An order of magnitude increase in the number of SNe is possible by analysing the full SDSS-I data base.

  16. Constraining Type Ia supernovae progenitor parameters via light curves

    NASA Astrophysics Data System (ADS)

    Sadler, Benjamin

    I study thermonuclear explosions of White Dwarf (WD) stars, or so-called Type Ia supernovae (SNe Ia). Higher precision is needed to determine the nature of the dark energy and to accomplish this we turn to secondary parameters of LC variation. I have devised a general scheme and developed a code to analyze large sets of LC data for these secondary parameter variations which is based on a combination of theoretical model template fitting and Principal Component Analysis. Novel methods for finding statistical trends in sparsely-sampled and non-coincidental light curve data are explored and utilized. In practice, data sets for different supernovae are inhomogeneous in time, time coverage and accuracy, but I have developed a method to remap these inhomogeneous data sets of large numbers of individual objects to a homogeneous data set centered in time and magnitude space from which we can obtain the external, primary, and secondary LC parameters of individual objects. The set of external parameters of a given SN include the time of its maximum light in various bands, its distance modulus, the extinction along the light path, and redshift corrections (K-corrections) due to cosmic expansion. I investigate the intrinsic primary parameter variation of SNe Ia via template fitting, and then probe the secondary LC variations using monochromatic differential analysis in the UBV bands. We use photometry from 25 SNe Ia which were recently and precisely observed by the Carnegie Supernova Project to analyze the presence of theoretical model-based differential LC signatures of Main-Sequence mass variation of the progenitor stars when they formed, central density variation of the WD at the time of the explosion, and metallicity Z variation in the progenitors. The light curves in the V band are found to provide the highest accuracy in determining the distance modulus, K-corrections, extinction, main-sequence mass and central density

  17. Progressive redshifts in the late-time spectra of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Black, C. S.; Fesen, R. A.; Parrent, J. T.

    2016-10-01

    We examine the evolution of late-time, optical nebular features of Type Ia supernovae (SNe Ia) using a sample consisting of 160 spectra of 27 normal SNe Ia taken from the literature as well as unpublished spectra of SN 2008Q and ASASSN-14lp. Particular attention was given to nebular features between 4000 and 6000 Å in terms of temporal changes in width and central wavelength. Analysis of the prominent late-time 4700 Å feature shows a progressive central wavelength shift from ˜4600 Å to longer wavelengths out to at least day +300 for our entire sample. We find no evidence for the feature's redward shift slowing or halting at an [Fe III] blend centroid ˜4700 Å as has been proposed. The width of this feature also steadily increases with a FWHM ˜170 Å at day +100 growing to 200 Å or more by day +350. Two weaker adjacent features at around 4850 and 5000 Å exhibit similar redshifts to that of the 4700 Å feature but show no change in width until very late times. We discuss possible causes for the observed redshifts of these late-time optical features including contribution from [Co II] emission at early nebular epochs and the emergence of additional features at later times. We conclude that the ubiquitous redshift of these common late-time SN Ia spectral features is not mainly due to a decrease in line velocities of forbidden Fe emissions, but the result of decreasing line velocities and opacity of permitted Fe absorption lines.

  18. Measuring cosmic bulk flows with Type Ia supernovae from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Feindt, U.; Kerschhaggl, M.; Kowalski, M.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Kim, A.; Nugent, P.; Nordin, J.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.

    2013-12-01

    Context. Our Local Group of galaxies appears to be moving relative to the cosmic microwave background with the source of the peculiar motion still uncertain. While in the past this has been studied mostly using galaxies as distance indicators, the weight of Type Ia supernovae (SNe Ia) has increased recently with the continuously improving statistics of available low-redshift supernovae. Aims: We measured the bulk flow in the nearby universe (0.015 < z < 0.1) using 117 SNe Ia observed by the Nearby Supernova Factory, as well as the Union2 compilation of SN Ia data already in the literature. Methods: The bulk flow velocity was determined from SN data binned in redshift shells by including a coherent motion (dipole) in a cosmological fit. Additionally, a method of spatially smoothing the Hubble residuals was used to verify the results of the dipole fit. To constrain the location and mass of a potential mass concentration (e.g., the Shapley supercluster) responsible for the peculiar motion, we fit a Hubble law modified by adding an additional mass concentration. Results: The analysis shows a bulk flow that is consistent with the direction of the CMB dipole up to z ~ 0.06, thereby doubling the volume over which conventional distance measures are sensitive to a bulk flow. We see no significant turnover behind the center of the Shapley supercluster. A simple attractor model in the proximity of the Shapley supercluster is only marginally consistent with our data, suggesting the need for another, more distant source. In the redshift shell 0.06 < z < 0.1, we constrain the bulk flow velocity to ≤240 km s-1 (68% confidence level) for the direction of the CMB dipole, in contradiction to recent claims of the existence of a large-amplitude dark flow.

  19. Reconciling the Infrared Catastrophe and Observations of SN 2011fe

    NASA Astrophysics Data System (ADS)

    Fransson, Claes; Jerkstrand, Anders

    2015-11-01

    The observational effects of the “Infrared Catastrophe” are discussed in view of the very late observations of the Type Ia SN 2011fe. Our model spectra at 1000 days take non-local radiative transfer into account and find that this has a crucial impact on the spectral formation. Although rapid cooling of the ejecta to a few 100 K occurs also in these models, the late-time optical/NIR flux is brighter by 1-2 mag due to redistribution of UV emissivity, resulting from non-thermal excitation and ionization. This effect brings models into better agreement with late-time observations of SN 2011fe, and other SNe Ia, and offers a solution to the long-standing discrepancy between models and observations. The models show that spectral formation shifts from Fe ii and Fe iii at 300 days to Fe i at 1000 days, which explains the apparent wavelength shifts seen in SN 2011fe. We discuss the effects of time dependence and energy input from 57Co, finding both to be important at 1000 days.

  20. RECONCILING THE INFRARED CATASTROPHE AND OBSERVATIONS OF SN 2011fe

    SciTech Connect

    Fransson, Claes; Jerkstrand, Anders

    2015-11-20

    The observational effects of the “Infrared Catastrophe” are discussed in view of the very late observations of the Type Ia SN 2011fe. Our model spectra at 1000 days take non-local radiative transfer into account and find that this has a crucial impact on the spectral formation. Although rapid cooling of the ejecta to a few 100 K occurs also in these models, the late-time optical/NIR flux is brighter by 1–2 mag due to redistribution of UV emissivity, resulting from non-thermal excitation and ionization. This effect brings models into better agreement with late-time observations of SN 2011fe, and other SNe Ia, and offers a solution to the long-standing discrepancy between models and observations. The models show that spectral formation shifts from Fe ii and Fe iii at 300 days to Fe i at 1000 days, which explains the apparent wavelength shifts seen in SN 2011fe. We discuss the effects of time dependence and energy input from {sup 57}Co, finding both to be important at 1000 days.

  1. ASYMMETRIC EJECTA DISTRIBUTION IN SN 1006

    SciTech Connect

    Uchida, Hiroyuki; Koyama, Katsuji; Yamaguchi, Hiroya

    2013-07-01

    We present the results from deep X-ray observations ({approx}400 ks in total) of SN 1006 with Suzaku. The thermal spectrum from the entire supernova remnant (SNR) exhibits prominent emission lines of O, Ne, Mg, Si, S, Ar, Ca, and Fe. The observed abundance pattern in the ejecta components is in good agreement with that predicted by a standard model of Type Ia supernovae (SNe). The spatially resolved analysis reveals that the distribution of the O-burning and incomplete Si-burning products (Si, S, and Ar) is asymmetric, while that of the C-burning products (O, Ne, and Mg) is relatively uniform in the SNR interior. The peak position of the former is clearly shifted by 5' ({approx}3.2 pc at the distance of 2.2 kpc) to the southeast (SE) from the SNR's geometric center. Using the SNR age of {approx}1000 yr, we constrain that the velocity asymmetry (in projection) of the ejecta is {approx}3100 km s{sup -1}. The Fe abundance is also significantly higher in the SE region than in the northwest. Given that the non-uniformity is observed only in the heavier elements (Si through Fe), we argue that SN 1006 originates from an asymmetric explosion, as is expected from recent multidimensional simulations of Type Ia SNe, although we cannot eliminate the possibility that inhomogeneous ambient medium had induced the apparent non-uniformity. Possible evidence for the Cr-K-shell line and line broadening in the Fe-K-shell emission is also found.

  2. VizieR Online Data Catalog: Velocities and EW of PTF SNe Ia (Maguire+, 2014)

    NASA Astrophysics Data System (ADS)

    Maguire, K.; Sullivan, M.; Pan, Y.-C.; Gal-Yam, A.; Hook, I. M.; Howell, D. A.; Nugent, P. E.; Mazzali, P.; Chotard, N.; Clubb, K. I.; Filippenko, A. V.; Kasliwal, M. M.; Kandrashoff, M. T.; Poznanski, D.; Saunders, C. M.; Silverman, J. M.; Walker, E.; Xu, D.

    2015-04-01

    We present spectroscopic classification and follow-up data for SNe Ia obtained as part of the PTF collaboration. SN candidates were discovered in P48 g- and R-band images using image-subtraction techniques. Photometry was obtained at the P48, as well as the 2-m robotic Liverpool Telescope (LT) and the Las Cumbres Observatory Global Telescope (LCOGT) Faulkes Telescope North (FTN). In this paper, we focus on the spectroscopic sample analysis and use only derived quantities from the light curves (light-curve width, time of B-band maximum light). (2 data files).

  3. LaRC(TM)-IA Copolyimides

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Chang, Alice C.

    1995-01-01

    Copolyimides modified versions of LaRC(TM)-IA thermoplastic polyimide formulated by incorporating moieties of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and, alternatively, isophthaloyldiphthalic anhydride (IDPA) into LaRC(TM)-IA polymer backbones. Exhibit higher glass-transition temperatures and retain greater fractions of lower-temperature shear moduli at higher temperatures. Copolyimides spun into fibers or used as adhesives, molding powders, or matrix resins in many applications, especially in fabrication of strong, lightweight structural components of aircraft.

  4. Hubble Space Telescope and Ground-based Observations of the Type Iax Supernovae SN 2005hk and SN 2008A

    NASA Astrophysics Data System (ADS)

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Frieman, Joshua; Fynbo, Johan; Galbany, Lluis; Ganeshalingam, Mohan; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leloudas, Giorgos; Leonard, Douglas C.; Li, Weidong; Riess, Adam G.; Sako, Masao; Schneider, Donald P.; Silverman, Jeffrey M.; Sollerman, Jesper; Steele, Thea N.; Thomas, Rollin C.; Wheeler, J. Craig; Zheng, Chen

    2014-05-01

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with ne >~ 109 cm-3. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected "infrared catastrophe," a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a "complete deflagration" that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  5. Hubble space telescope and ground-based observations of the type Iax supernovae SN 2005hk and SN 2008A

    SciTech Connect

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Frieman, Joshua; Fynbo, Johan; Leloudas, Giorgos; Galbany, Lluis; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leonard, Douglas C.; and others

    2014-05-10

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with n{sub e} ≳ 10{sup 9} cm{sup –3}. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected 'infrared catastrophe', a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a 'complete deflagration' that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  6. A Spherical Chandrasekhar-Mass Delayed-Detonation Model for a Normal Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Blondin, Stéphane; Dessart, Luc; Hillier, D. John

    2015-06-01

    The most widely-accepted model for Type Ia supernovae (SNe Ia) is the thermonuclear disruption of a White Dwarf (WD) star in a binary system, although there is ongoing discussion about the combustion mode, the progenitor mass, and the nature of the binary companion. Observational evidence for diversity in the SN Ia population seems to require multiple progenitor channels or explosion mechanisms. In the standard single-degenerate (SD) scenario, the WD grows in mass through accretion of H-rich or He-rich material from a non-degenerate donor (e.g., a main-sequence star, a subgiant, a He star, or a red giant). When the WD is sufficiently close to the Chandrasekhar limit (˜1.4 M⊙), a subsonic deflagration front forms near the WD center which eventually transitions to a supersonic detonation (the so-called “delayed-detonation” model) and unbinds the star. The efficiency of the WD growth in mass remains uncertain, as repeated nova outbursts during the accretion process result in mass ejection from the WD surface. Moreover, the lack of observational signatures of the binary companion has cast some doubts on the SD scenario, and recent hydrodynamical simulations have put forward WD-WD mergers and collisions as viable alternatives. However, as shown here, the standard Chandrasekhar-mass delayed-detonation model remains adequate to explain many normal SNe Ia, in particular those displaying broad Si II 6355 Å lines. We present non-local-thermodynamic-equilibrium time-dependent radiative transfer simulations performed with CMFGEN of a spherically-symmetric delayed-detonation model from a Chandrasekhar-mass WD progenitor with 0.51 M⊙ of 56Ni (Fig. 1 and Table 1), and confront our results to the observed light curves and spectra of the normal Type Ia SN 2002bo over the first 100 days of its evolution. With no fine tuning, the model reproduces well the bolometric (Fig. 2) and multi-band light curves, the secondary near-infrared maxima (Fig. 3), and the spectroscopic

  7. Optical and near-infrared observations of SN 2014ck: an outlier among the Type Iax supernovae

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Cappellaro, E.; Benetti, S.; Pastorello, A.; Hsiao, E. Y.; Sand, D. J.; Stritzinger, M.; Valenti, S.; McCully, C.; Arcavi, I.; Elias-Rosa, N.; Harmanen, J.; Harutyunyan, A.; Hosseinzadeh, G.; Howell, D. A.; Kankare, E.; Morales-Garoffolo, A.; Taddia, F.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-06-01

    We present a comprehensive set of optical and near-infrared (NIR) photometric and spectroscopic observations for SN 2014ck, extending from pre-maximum to six months later. These data indicate that SN 2014ck is photometrically nearly identical to SN 2002cx, which is the prototype of the class of peculiar transients named SNe Iax. Similar to SN 2002cx, SN 2014ck reached a peak brightness MB = -17.37 ± 0.15 mag, with a post-maximum decline rate Δm15(B) = 1.76 ± 0.15 mag. However, the spectroscopic sequence shows similarities with SN 2008ha, which was three magnitudes fainter and faster declining. In particular, SN 2014ck exhibits extremely low ejecta velocities, ˜3000 km s-1 at maximum, which are close to the value measured for SN 2008ha and half the value inferred for SN 2002cx. The bolometric light curve of SN 2014ck is consistent with the production of 0.10^{+0.04}_{-0.03} M_{{⊙}} of 56Ni. The spectral identification of several iron-peak features, in particular Co II lines in the NIR, provides a clear link to SNe Ia. Also, the detection of narrow Si, S and C features in the pre-maximum spectra suggests a thermonuclear explosion mechanism. The late-phase spectra show a complex overlap of both permitted and forbidden Fe, Ca and Co lines. The appearance of strong [Ca II] λλ7292, 7324 again mirrors the late-time spectra of SN 2008ha and SN 2002cx. The photometric resemblance to SN 2002cx and the spectral similarities to SN 2008ha highlight the peculiarity of SN 2014ck, and the complexity and heterogeneity of the SNe Iax class.

  8. Type Ia Supernova Hubble Residuals and Host-Galaxy Properties

    SciTech Connect

    Nearby Supernova Factory; Kim, A. G.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fleury, M.; Gangler, E.; Greskovic, P.; Guy, J.; Kowalski, M.; Lombardo, S.; Nordin, J.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.

    2014-01-17

    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.

  9. Type Ia Supernova Hubble Residuals and Host-galaxy Properties

    NASA Astrophysics Data System (ADS)

    Kim, A. G.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fleury, M.; Gangler, E.; Greskovic, P.; Guy, J.; Kowalski, M.; Lombardo, S.; Nordin, J.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.

    2014-03-01

    Kim et al. 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 spectrophotometric 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 Lt1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the 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 parameters: steps at >2σ 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 Δm 15 and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 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.

  10. Type Ia supernova Hubble residuals and host-galaxy properties

    SciTech Connect

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Fleury, M.; Guy, J.; Baltay, C.; Buton, C.; Feindt, U.; Greskovic, P.; Kowalski, M.; Childress, M.; Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, F-69622 Lyon; Université de Lyon 1, Villeurbanne; CNRS and others

    2014-03-20

    Kim et al. 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 spectrophotometric 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 <<1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the 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 parameters: steps at >2σ 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 Δm {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 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.

  11. VizieR Online Data Catalog: SDSS-II SN Survey: host-galaxy spectral data (Wolf+, 2016)

    NASA Astrophysics Data System (ADS)

    Wolf, R. C.; D'Andrea, C. B.; Gupta, R. R.; Sako, M.; Fischer, J. A.; Kessler, R.; Jha, S. W.; March, M. C.; Scolnic, D. M.; Fischer, J.-L.; Campbell, H.; Nichol, R. C.; Olmstead, M. D.; Richmond, M.; Schneider, D. P.; Smith, M.

    2016-07-01

    Observations from the full 3yr SDSS-II Supernova Survey (SDSS-SNS; Sako et al. 2014, arXiv:1401.3317) were used for our SN Ia sample, and a combination of spectra from SDSS and BOSS was utilized for host-galaxy spectroscopy. (1 data file).

  12. SPECTROPOLARIMETRY OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc: NEARLY SPHERICAL EXPLOSION OF SUPER-CHANDRASEKHAR MASS WHITE DWARF

    SciTech Connect

    Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken'ichi; Kawabata, Koji S.; Yamanaka, Masayuki; Hattori, Takashi; Aoki, Kentaro; Sasaki, Toshiyuki; Iye, Masanori; Mazzali, Paolo A.; Pian, Elena

    2010-05-10

    We present the first spectropolarimetric observations of a candidate of super-Chandrasekhar mass Type Ia supernova (SN): SN 2009dc. The observations were performed at 5.6 and 89.5 days after the B-band maximum. The data taken at the later epoch are used to determine the interstellar polarization. Continuum polarization is found to be small (<0.3%), indicating that the explosion is nearly spherically symmetric. This fact suggests that a very aspherical explosion is not a likely scenario for SN 2009dc. Polarization at the Si II and Ca II lines clearly shows a loop in the Q-U plane, indicating a non-axisymmetric, clumpy distribution of intermediate-mass elements. The degree of line polarization at the Si and Ca lines is moderate (0.5% {+-} 0.1% and 0.7% {+-} 0.1%, respectively), but it is higher than expected from the trend of other Type Ia SNe. This may suggest that there are thick enough, clumpy Si-rich layers above the thick {sup 56}Ni-rich layers ({approx_gt}1.2 M{sub sun}). The observed spectropolarimetric properties, combined with the photometric and spectroscopic properties, suggest that the progenitor of SN 2009dc has a super-Chandrasekhar mass, and that the explosion geometry is globally spherically symmetric, with clumpy distribution of intermediate-mass elements.

  13. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    SciTech Connect

    Mandel, Kaisey S.; Kirshner, Robert P.; Foley, Ryan J.

    2014-12-20

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10{sup 3} km s{sup –1}){sup –1} for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A{sub V} extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances.

  14. Exploring the spectroscopic diversity of Type Ia supernovae with DRACULA: a machine learning approach

    NASA Astrophysics Data System (ADS)

    Sasdelli, M.; Ishida, E. E. O.; Vilalta, R.; Aguena, M.; Busti, V. C.; Camacho, H.; Trindade, A. M. M.; Gieseke, F.; de Souza, R. S.; Fantaye, Y. T.; Mazzali, P. A.

    2016-09-01

    The existence of multiple subclasses of Type Ia supernovae (SNe Ia) has been the subject of great debate in the last decade. One major challenge inevitably met when trying to infer the existence of one or more subclasses is the time consuming, and subjective, process of subclass definition. In this work, we show how machine learning tools facilitate identification of subtypes of SNe Ia through the establishment of a hierarchical group structure in the continuous space of spectral diversity formed by these objects. Using deep learning, we were capable of performing such identification in a four-dimensional feature space (+1 for time evolution), while the standard principal component analysis barely achieves similar results using 15 principal components. This is evidence that the progenitor system and the explosion mechanism can be described by a small number of initial physical parameters. As a proof of concept, we show that our results are in close agreement with a previously suggested classification scheme and that our proposed method can grasp the main spectral features behind the definition of such subtypes. This allows the confirmation of the velocity of lines as a first-order effect in the determination of SN Ia subtypes, followed by 91bg-like events. Given the expected data deluge in the forthcoming years, our proposed approach is essential to allow a quick and statistically coherent identification of SNe Ia subtypes (and outliers). All tools used in this work were made publicly available in the PYTHON package Dimensionality Reduction And Clustering for Unsupervised Learning in Astronomy (DRACULA) and can be found within COINtoolbox (https://github.com/COINtoolbox/DRACULA).

  15. Uncovering the putative B-star binary companion of the SN 1993J progenitor

    SciTech Connect

    Fox, Ori D.; Filippenko, Alexei V.; Bradley Cenko, S.; Li, Weidong; Parker, Alex H.; Azalee Bostroem, K.; Van Dyk, Schuyler D.; Fransson, Claes; Matheson, Thomas; Chandra, Poonam; Dwarkadas, Vikram; Smith, Nathan

    2014-07-20

    The Type IIb supernova (SN) 1993J is one of only a few stripped-envelope SNe with a progenitor star identified in pre-explosion images. SN IIb models typically invoke H envelope stripping by mass transfer in a binary system. For the case of SN 1993J, the models suggest that the companion grew to 22 M{sub ☉} and became a source of ultraviolet (UV) excess. Located in M81, at a distance of only 3.6 Mpc, SN 1993J offers one of the best opportunities to detect the putative companion and test the progenitor model. Previously published near-UV spectra in 2004 showed evidence for absorption lines consistent with a hot (B2 Ia) star, but the field was crowded and dominated by flux from the SN. Here we present Hubble Space Telescope Cosmic Origins Spectrograph and Wide-Field Camera 3 observations of SN 1993J from 2012, at which point the flux from the SN had faded sufficiently to potentially measure the UV continuum properties from the putative companion. The resulting UV spectrum is consistent with contributions from both a hot B star and the SN, although we cannot rule out line-of-sight coincidences.

  16. Uncovering the Putative B-Star Binary Companion of the SN 1993J Progenitor

    NASA Technical Reports Server (NTRS)

    Fox, Ori D.; Bostroem, K. Azalee; Van Dyk, Schuyler D.; Filippenko, Alexei V.; Fransson, Claes; Matheson, Thomas; Cenko, S. Bradley; Chandra, Poonam; Dwarkadas, Vikram; Li, Weidong; Parker, Alex H.; Smith, Nathan

    2014-01-01

    The Type IIb supernova (SN) 1993J is one of only a few stripped-envelope SNe with a progenitor star identified in pre-explosion images. SN IIb models typically invoke H envelope stripping by mass transfer in a binary system. For the case of SN 1993J, the models suggest that the companion grew to 22 solar mass and became a source of ultraviolet (UV) excess. Located in M81, at a distance of only 3.6 Mpc, SN 1993J offers one of the best opportunities to detect the putative companion and test the progenitor model. Previously published near-UV spectra in 2004 showed evidence for absorption lines consistent with a hot (B2 Ia) star, but the field was crowded and dominated by flux from the SN. Here we present Hubble Space Telescope Cosmic Origins Spectrograph and Wide-Field Camera 3 observations of SN 1993J from 2012, at which point the flux from the SN had faded sufficiently to potentially measure the UV continuum properties from the putative companion. The resulting UV spectrum is consistent with contributions from both a hot B star and the SN, although we cannot rule out line-of-sight coincidences.

  17. Determining Type Ia Supernova Host Galaxy Extinction Probabilities and a Statistical Approach to Estimating the Absorption-to-reddening Ratio RV

    NASA Astrophysics Data System (ADS)

    Cikota, Aleksandar; Deustua, Susana; Marleau, Francine

    2016-03-01

    We investigate limits on the extinction values of Type Ia supernovae (SNe Ia) to statistically determine the most probable color excess, E(B - V), with galactocentric distance, and use these statistics to determine the absorption-to-reddening ratio, RV, for dust in the host galaxies. We determined pixel-based dust mass surface density maps for 59 galaxies from the Key Insight on Nearby Galaxies: a Far-infrared Survey with Herschel (KINGFISH). We use SN Ia spectral templates to develop a Monte Carlo simulation of color excess E(B - V) with RV = 3.1 and investigate the color excess probabilities E(B - V) with projected radial galaxy center distance. Additionally, we tested our model using observed spectra of SN 1989B, SN 2002bo, and SN 2006X, which occurred in three KINGFISH galaxies. Finally, we determined the most probable reddening for Sa-Sap, Sab-Sbp, Sbc-Scp, Scd-Sdm, S0, and irregular galaxy classes as a function of R/R25. We find that the largest expected reddening probabilities are in Sab-Sb and Sbc-Sc galaxies, while S0 and irregular galaxies are very dust poor. We present a new approach for determining the absorption-to-reddening ratio RV using color excess probability functions and find values of RV = 2.71 ± 1.58 for 21 SNe Ia observed in Sab-Sbp galaxies, and RV = 1.70 ± 0.38, for 34 SNe Ia observed in Sbc-Scp galaxies.

  18. FAILED-DETONATION SUPERNOVAE: SUBLUMINOUS LOW-VELOCITY Ia SUPERNOVAE AND THEIR KICKED REMNANT WHITE DWARFS WITH IRON-RICH CORES

    SciTech Connect

    Jordan, George C. IV; Van Rossum, Daniel R.; Perets, Hagai B.; Fisher, Robert T.

    2012-12-20

    Type Ia supernovae (SNe Ia) originate from the thermonuclear explosions of carbon-oxygen (C-O) white dwarfs (WDs). The single-degenerate scenario is a well-explored model of SNe Ia where unstable thermonuclear burning initiates in an accreting, Chandrasekhar-mass WD and forms an advancing flame. By several proposed physical processes, the rising, burning material triggers a detonation, which subsequently consumes and unbinds the WD. However, if a detonation is not triggered and the deflagration is too weak to unbind the star, a completely different scenario unfolds. We explore the failure of the gravitationally confined detonation mechanism of SNe Ia, and demonstrate through two-dimensional and three-dimensional simulations the properties of failed-detonation SNe. We show that failed-detonation SNe expel a few 0.1 M{sub Sun} of burned and partially burned material and that a fraction of the material falls back onto the WD, polluting the remnant WD with intermediate-mass and iron-group elements that likely segregate to the core forming a WD whose core is iron rich. The remaining material is asymmetrically ejected at velocities comparable to the escape velocity from the WD, and in response, the WD is kicked to velocities of a few hundred km s{sup -1}. These kicks may unbind the binary and eject a runaway/hypervelocity WD. Although the energy and ejected mass of the failed-detonation SN are a fraction of typical thermonuclear SNe, they are likely to appear as subluminous low-velocity SNe Ia. Such failed detonations might therefore explain or are related to the observed branch of peculiar SNe Ia, such as the family of low-velocity subluminous SNe (SN 2002cx/SN 2008ha-like SNe).

  19. Failed-detonation Supernovae: Subluminous Low-velocity Ia Supernovae and their Kicked Remnant White Dwarfs with Iron-rich Cores

    NASA Astrophysics Data System (ADS)

    Jordan, George C., IV; Perets, Hagai B.; Fisher, Robert T.; van Rossum, Daniel R.

    2012-12-01

    Type Ia supernovae (SNe Ia) originate from the thermonuclear explosions of carbon-oxygen (C-O) white dwarfs (WDs). The single-degenerate scenario is a well-explored model of SNe Ia where unstable thermonuclear burning initiates in an accreting, Chandrasekhar-mass WD and forms an advancing flame. By several proposed physical processes, the rising, burning material triggers a detonation, which subsequently consumes and unbinds the WD. However, if a detonation is not triggered and the deflagration is too weak to unbind the star, a completely different scenario unfolds. We explore the failure of the gravitationally confined detonation mechanism of SNe Ia, and demonstrate through two-dimensional and three-dimensional simulations the properties of failed-detonation SNe. We show that failed-detonation SNe expel a few 0.1 M ⊙ of burned and partially burned material and that a fraction of the material falls back onto the WD, polluting the remnant WD with intermediate-mass and iron-group elements that likely segregate to the core forming a WD whose core is iron rich. The remaining material is asymmetrically ejected at velocities comparable to the escape velocity from the WD, and in response, the WD is kicked to velocities of a few hundred km s-1. These kicks may unbind the binary and eject a runaway/hypervelocity WD. Although the energy and ejected mass of the failed-detonation SN are a fraction of typical thermonuclear SNe, they are likely to appear as subluminous low-velocity SNe Ia. Such failed detonations might therefore explain or are related to the observed branch of peculiar SNe Ia, such as the family of low-velocity subluminous SNe (SN 2002cx/SN 2008ha-like SNe).

  20. Constraints on the progenitor system and the environs of SN 2014J from deep EVN and MERLIN radio observations

    NASA Astrophysics Data System (ADS)

    Perez-Torres, M.; Lundqvist, P.; Beswick, R. J.; Björnsson, C. I.; Muxlow, T. W. B.; Paragi, Z.; Ryder, S.; Alberdi, A.; Fransson, C.; Marcaide, J. M.; Ros, E.; Argo, M. K.; Guirado, J. C.

    We report the deepest radio interferometric observations of the closest Type Ia supernova in decades, SN 2014J, which exploded in the nearby galaxy M 82. These observations represent, together with radio observations of SNe 2011fe, the most sensitive radio studies of a Type Ia SN ever. We constrain the mass-loss rate from the progenitor system of SN 2014J to dM/dt &t;~ 7×10-10 M_sun/yr (for a wind speed of 100 km/s). Most single-degenerate scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to a exploding white dwarf, are ruled out by our observations. On the contrary, our stringent upper limits to the radio emission from SN 2014 favor a double-degenerate scenario - involving two WD stars - for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. Thus, the evidence from SNe 2011fe and 2014J points in the direction of a double-degenerate scenario for both. Looking into the future, we note that the huge improvement in sensitivity of the SKA with respect to its predecessors will allow us to determine which progenitor scenario (single-degenerate vs. double-degenerate) applies to a large sample of nearby Type Ia SNe, thus unambiguously solving this issue.

  1. The reionization of unshocked ejecta in SN 1006

    NASA Technical Reports Server (NTRS)

    Hamilton, Andrew J. S.; Fesen, Robert A.

    1988-01-01

    The validity of carbon-deflagration models white dwarf models for type Ia supernovae is investigated by examining whether most of the iron in the center of SN 1006 exists in forms other than Fe II, such as iron grains or other ionic stages of iron, as the models require. The possible ways in which iron can be hidden in SN 1006 are reviewed, and an argument on observational grounds is made against any appreciable fraction of iron in grains or Fe I. Various mechanisms for ionizing unshocked iron beyond Fe II are discussed; the most probable mechanism for ionizing the iron appears to be photoionization by UV and X-ray emission from reverse-shocked ejecta. A detailed model for this reverse-shcok photoionization mechanism is described.

  2. The Critical Mass Ratio of Double White Dwarf Binaries for Violent Merger-induced Type Ia Supernova Explosions

    NASA Astrophysics Data System (ADS)

    Sato, Yushi; Nakasato, Naohito; Tanikawa, Ataru; Nomoto, Ken’ichi; Maeda, Keiichi; Hachisu, Izumi

    2016-04-01

    Mergers of carbon–oxygen (CO) white dwarfs (WDs) are considered to be one of the potential progenitors of type Ia supernovae (SNe Ia). Recent hydrodynamical simulations showed that the less massive (secondary) WD violently accretes onto the more massive (primary) one, carbon detonation occurs, the detonation wave propagates through the primary, and the primary finally explodes as a sub-Chandrasekhar mass SN Ia. Such an explosion mechanism is called the violent merger scenario. Based on the smoothed particle hydrodynamics simulations of merging CO WDs, we derived a critical mass ratio (qcr) leading to the violent merger scenario that is more stringent than previous results. We conclude that this difference mainly comes from the differences in the initial condition of whether or not the WDs are synchronously spinning. Using our new results, we estimated the brightness distribution of SNe Ia in the violent merger scenario and compared it with previous studies. We found that our new qcr does not significantly affect the brightness distribution. We present the direct outcome immediately following CO WD mergers for various primary masses and mass ratios. We also discussed the final fate of the central system of the bipolar planetary nebula Henize 2-428, which was recently suggested to be a double CO WD system whose total mass exceeds the Chandrasekhar-limiting mass, merging within the Hubble time. Even considering the uncertainties in the proposed binary parameters, we concluded that the final fate of this system is almost certainly a sub-Chandrasekhar mass SN Ia in the violent merger scenario.

  3. Spectral Observations and Analyses of Low-Redshift Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey Michael

    The explosive deaths of stars, known as a supernovae (SNe), have been critical to our understanding of the Universe for centuries. An introduction to SNe, their importance in astronomy, and how we observe them is given in Chapter 1. In the second Chapter, I present the full BSNIP sample which consists of 1298 low-redshift (z ≤ 0.2) optical spectra of 582 SNe Ia observed from 1989 through the end of 2008. I describe our spectral classification scheme (using the SuperNova IDentification code, SNID; Blondin & Tonry 2007), utilizing my newly constructed set of SNID spectral templates. These templates allow me to accurately spectroscopically classify the entire BSNIP dataset, and by doing so I am able to reclassify a handful of objects as bona fide SNe Ia and a few other objects as members of some of the peculiar SN Ia subtypes. In fact, the BSNIP dataset includes spectra of nearly 90 spectroscopically peculiar SNe Ia. I also present spectroscopic host-galaxy redshifts of some SNe Ia where these values were previously unknown. I present measurements of spectral features of 432 low-redshift ( z < 0.1) optical spectra within 20 d of maximum brightness of 261 SNe Ia from the BSNIP sample in the third Chapter. I describe in detail my method of automated, robust spectral feature definition and measurement which expands upon similar previous studies. Using this procedure, I attempt to measure expansion velocities, (pseudo-)equivalent widths (pEWs), spectral feature depths, and fluxes at the center and endpoints of each of nine major spectral feature complexes. A sanity check of the consistency of the measurements is performed using the BSNIP data (as well as a separate spectral dataset). I investigate how velocity and pEW evolve with time and how they correlate with each other. Various spectral classification schemes are employed and quantitative spectral differences among the subclasses are investigated. Several ratios of pEW values are calculated and studied. Furthermore

  4. THE DISTANCE TO M101 HOSTING TYPE Ia SUPERNOVA 2011fe BASED ON THE TIP OF THE RED GIANT BRANCH

    SciTech Connect

    Lee, Myung Gyoon; Jang, In Sung E-mail: isjang@astro.snu.ac.kr

    2012-11-20

    We present a new determination of the distance to M101, host of the Type Ia supernova (SN Ia) 2011fe, based on the tip of the red giant branch (TRGB) method. Our determination is based on Hubble Space Telescope archival F555W and F814W images of nine fields within the galaxy. Color-magnitude diagrams of arm-free regions in all fields show a prominent red giant branch. We measure the I-band magnitudes of the TRGB, obtaining a mean value of I{sub TRGB} = 25.28 {+-} 0.01 (where the error is a standard error), using an edge-detection method. We derive a weighted mean value of distance modulus (m - M){sub 0} = 29.30 {+-} 0.01(random) {+-} 0.12(systematic), corresponding to a linear distance of 7.24 {+-} 0.03 {+-} 0.40 Mpc. While previous estimates for M101 show a large range (TRGB distances of (m - M){sub 0} = 29.05-29.42 and Cepheid distances of (m - M){sub 0} = 29.04-29.71), our measurements of the TRGB distances for nine fields show a small dispersion of only 0.02. We combine our distance estimate and photometry in the literature to derive absolute peak magnitudes in optical and near-infrared bands of SN 2011fe. Absolute maximum magnitudes of SN 2011fe are {approx}0.2 mag brighter in the optical band and much more in the NIR than the current calibrations of SNe Ia in the literature. From the optical maximum magnitudes of SN 2011fe we obtain a value of the Hubble constant, H{sub 0} = 65.0 {+-} 0.5(random) {+-} 5.7(systematic) km s{sup -1} Mpc{sup -1}, slightly smaller than other recent determinations of H{sub 0}.

  5. Cloud Infrastructure & Applications - CloudIA

    NASA Astrophysics Data System (ADS)

    Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

    The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure that leverages different virtualization technologies, by supporting Service-Level Agreements for various service offerings. This paper describes the CloudIA project in details and mentions our early experiences in building a private cloud using an existing infrastructure.

  6. Unbiased Estimate of Dark Energy Density from Type Ia Supernova Data

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Lovelace, Geoffrey

    2001-12-01

    Type Ia supernovae (SNe Ia) are currently the best probes of the dark energy in the universe. To constrain the nature of dark energy, we assume a flat universe and that the weak energy condition is satisfied, and we allow the density of dark energy, ρX(z), to be an arbitrary function of redshift. Using simulated data from a space-based SN pencil-beam survey, we find that by optimizing the number of parameters used to parameterize the dimensionless dark energy density, f(z)=ρX(z)/ρX(z=0), we can obtain an unbiased estimate of both f(z) and the fractional matter density of the universe, Ωm. A plausible SN pencil-beam survey (with a square degree field of view and for an observational duration of 1 yr) can yield about 2000 SNe Ia with 0<=z<=2. Such a survey in space would yield SN peak luminosities with a combined intrinsic and observational dispersion of σ(mint)=0.16 mag. We find that for such an idealized survey, Ωm can be measured to 10% accuracy, and the dark energy density can be estimated to ~20% to z~1.5, and ~20%-40% to z~2, depending on the time dependence of the true dark energy density. Dark energy densities that vary more slowly can be more accurately measured. For the anticipated Supernova/Acceleration Probe (SNAP) mission, Ωm can be measured to 14% accuracy, and the dark energy density can be estimated to ~20% to z~1.2. Our results suggest that SNAP may gain much sensitivity to the time dependence of the dark energy density and Ωm by devoting more observational time to the central pencil-beam fields to obtain more SNe Ia at z>1.2. We use both a maximum likelihood analysis and a Monte Carlo analysis (when appropriate) to determine the errors of estimated parameters. We find that the Monte Carlo analysis gives a more accurate estimate of the dark energy density than the maximum likelihood analysis.

  7. Restframe I-band Hubble diagram for type Ia supernovae up toredshift z ~; 0.5

    SciTech Connect

    Nobili, S.; Amanullah, R.; Garavini, G.; Goobar, A.; Lidman, C.; Stanishev, V.; Aldering, G.; Antilogus, P.; Astier, P.; Burns, M.S.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fadeyev, V.; Folatelli,G.; Gibbons, R.; Goldhaber, G.; Groom, D.E.; Hook, I.; Howell, D.A.; Kim,A.G.; Knop, R.A.; Nugent, P.E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Thomas, R.C.; Wang, L.

    2005-04-01

    We present a novel technique for fitting rest frame I-bandlight curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z {approx} 0.5 yields results consistent with a flat Lambda-dominated ''concordance universe'' (OmegaM,Omega Lambda) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, Lambda = 0, universe where the faintness of supernovae at z {approx} 0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavored based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B - I and B - V color measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous.

  8. Evolution in the Volumetric Type Ia Supernova Rate from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Perrett, K.; Sullivan, M.; Conley, A.; González-Gaitán, S.; Carlberg, R.; Fouchez, D.; Ripoche, P.; Neill, J. D.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Guy, J.; Hardin, D.; Hook, I. M.; Howell, D. A.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C.; Regnault, N.; Rich, J.; Ruhlmann-Kleider, V.; Baumont, S.; Lidman, C.; Perlmutter, S.; Walker, E. S.

    2012-08-01

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate (SNRIa) as a function of redshift for the first four years of data from the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). This analysis includes 286 spectroscopically confirmed and more than 400 additional photometrically identified SNe Ia within the redshift range 0.1 <= z <= 1.1. The volumetric SNRIa evolution is consistent with a rise to z ~ 1.0 that follows a power law of the form (1+z)α, with α = 2.11 ± 0.28. This evolutionary trend in the SNLS rates is slightly shallower than that of the cosmic star formation history (SFH) over the same redshift range. We combine the SNLS rate measurements with those from other surveys that complement the SNLS redshift range, and fit various simple SN Ia delay-time distribution (DTD) models to the combined data. A simple power-law model for the DTD (i.e., vpropt -β) yields values from β = 0.98 ± 0.05 to β = 1.15 ± 0.08 depending on the parameterization of the cosmic SFH. A two-component model, where SNRIa is dependent on stellar mass (M stellar) and star formation rate (SFR) as SNRIa(z) = A × M stellar(z) + B × SFR(z), yields the coefficients A = (1.9 ± 0.1) × 10-14 SNe yr-1 M -1 ⊙ and B = (3.3 ± 0.2) × 10-4 SNe yr-1 (M ⊙ yr-1)-1. More general two-component models also fit the data well, but single Gaussian or exponential DTDs provide significantly poorer matches. Finally, we split the SNLS sample into two populations by the light-curve width (stretch), and show that the general behavior in the rates of faster-declining SNe Ia (0.8 <= s < 1.0) is similar, within our measurement errors, to that of the slower objects (1.0 <= s < 1.3) out to z ~ 0.8.

  9. Bioengineered human IAS reconstructs with functional and molecular properties similar to intact IAS.

    PubMed

    Singh, Jagmohan; Rattan, Satish

    2012-09-15

    Because of its critical importance in rectoanal incontinence, we determined the feasibility to reconstruct internal anal sphincter (IAS) from human IAS smooth muscle cells (SMCs) with functional and molecular attributes similar to the intact sphincter. The reconstructs were developed using SMCs from the circular smooth muscle layer of the human IAS, grown in smooth muscle differentiation media under sterile conditions in Sylgard-coated tissue culture plates with central Sylgard posts. The basal tone in the reconstructs and its changes were recorded following 0 Ca(2+), KCl, bethanechol, isoproterenol, protein kinase C (PKC) activator phorbol 12,13-dibutyrate, and Rho kinase (ROCK) and PKC inhibitors Y-27632 and Gö-6850, respectively. Western blot (WB), immunofluorescence (IF), and immunocytochemical (IC) analyses were also performed. The reconstructs developed spontaneous tone (0.68 ± 0.26 mN). Bethanechol (a muscarinic agonist) and K(+) depolarization produced contraction, whereas isoproterenol (β-adrenoceptor agonist) and Y-27632 produced a concentration-dependent decrease in the tone. Maximal decrease in basal tone with Y-27632 and Gö-6850 (each 10(-5) M) was 80.45 ± 3.29 and 17.76 ± 3.50%, respectively. WB data with the IAS constructs' SMCs revealed higher levels of RhoA/ROCK, protein kinase C-potentiated inhibitor or inhibitory phosphoprotein for myosin phosphatase (CPI-17), phospho-CPI-17, MYPT1, and 20-kDa myosin light chain vs. rectal smooth muscle. WB, IF, and IC studies of original SMCs and redispersed from the reconstructs for the relative distribution of different signal transduction proteins confirmed the feasibility of reconstruction of IAS with functional properties similar to intact IAS and demonstrated the development of myogenic tone with critical dependence on RhoA/ROCK. We conclude that it is feasible to bioengineer IAS constructs using human IAS SMCs that behave like intact IAS.

  10. Uncertainties and robustness of the ignition process in type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Iapichino, L.; Lesaffre, P.

    2010-03-01

    Context. It is widely accepted that the onset of the explosive carbon burning in the core of a carbon-oxygen white dwarf (CO WD) triggers the ignition of a type Ia supernova (SN Ia). The features of the ignition are among the few free parameters of the SN Ia explosion theory. Aims: We explore the role for the ignition process of two different issues: firstly, the ignition is studied in WD models coming from different accretion histories. Secondly, we estimate how a different reaction rate for C-burning can affect the ignition. Methods: Two-dimensional hydrodynamical simulations of temperature perturbations in the WD core (“bubbles”) are performed with the FLASH code. In order to evaluate the impact of the C-burning reaction rate on the WD model, the evolution code FLASH_THE_TORTOISE from Lesaffre et al. (2006, MNRAS, 368, 187) is used. Results: In different WD models a key role is played by the different gravitational acceleration in the progenitor's core. As a consequence, the ignition is disfavored at a large distance from the WD center in models with a larger central density, resulting from the evolution of initially more massive progenitors. Changes in the C reaction rate at T ⪉ 5 × 10^8~K slightly influence the ignition density in the WD core, while the ignition temperature is almost unaffected. Recent measurements of new resonances in the C-burning reaction rate (Spillane et al. 2007, Phys. Rev. Lett., 98, 122501) do not affect the core conditions of the WD significantly. Conclusions: This simple analysis, performed on the features of the temperature perturbations in the WD core, should be extended in the framework of the state-of-the-art numerical tools for studying the turbulent convection and ignition in the WD core. Future measurements of the C-burning reactions cross section at low energy, though certainly useful, are not expected to affect our current understanding of the ignition process dramatically.

  11. Three-dimensional delayed-detonation models with nucleosynthesis for Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Ciaraldi-Schoolmann, Franco; Röpke, Friedrich K.; Fink, Michael; Hillebrandt, Wolfgang; Kromer, Markus; Pakmor, Rüdiger; Ruiter, Ashley J.; Sim, Stuart A.; Taubenberger, Stefan

    2013-02-01

    We present results for a suite of 14 three-dimensional, high-resolution hydrodynamical simulations of delayed-detonation models of Type Ia supernova (SN Ia) explosions. This model suite comprises the first set of three-dimensional SN Ia simulations with detailed isotopic yield information. As such, it may serve as a data base for Chandrasekhar-mass delayed-detonation model nucleosynthetic yields and for deriving synthetic observables such as spectra and light curves. We employ a physically motivated, stochastic model based on turbulent velocity fluctuations and fuel density to calculate in situ the deflagration-to-detonation transition probabilities. To obtain different strengths of the deflagration phase and thereby different degrees of pre-expansion, we have chosen a sequence of initial models with 1, 3, 5, 10, 20, 40, 100, 150, 200, 300 and 1600 (two different realizations) ignition kernels in a hydrostatic white dwarf with a central density of 2.9 × 109 g cm-3, as well as one high central density (5.5 × 109 g cm-3) and one low central density (1.0 × 109 g cm-3) rendition of the 100 ignition kernel configuration. For each simulation, we determined detailed nucleosynthetic yields by post-processing 106 tracer particles with a 384 nuclide reaction network. All delayed-detonation models result in explosions unbinding the white dwarf, producing a range of 56Ni masses from 0.32 to 1.11 M⊙. As a general trend, the models predict that the stable neutron-rich iron-group isotopes are not found at the lowest velocities, but rather at intermediate velocities (˜3000-10 000 km s-1) in a shell surrounding a 56Ni-rich core. The models further predict relatively low-velocity oxygen and carbon, with typical minimum velocities around 4000 and 10 000 km s-1, respectively.

  12. Two SNe Ia at Redshift ˜2: Improved Classification and Redshift Determination with Medium-band Infrared Imaging

    NASA Astrophysics Data System (ADS)

    Rodney, Steven A.; Riess, Adam G.; Scolnic, Daniel M.; Jones, David O.; Hemmati, Shoubaneh; Molino, Alberto; McCully, Curtis; Mobasher, Bahram; Strolger, Louis-Gregory; Graur, Or; Hayden, Brian; Casertano, Stefano

    2015-11-01

    We present two supernovae (SNe) discovered with the Hubble Space Telescope (HST) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, an HST multi-cycle treasury program. We classify both objects as SNe Ia and find redshifts of z = 1.80 ± 0.02 and 2.26+0.02-0.10, the latter of which is the highest redshift SN Ia yet seen. Using light curve fitting we determine luminosity distances and find that both objects are consistent with a standard ΛCDM cosmological model. These SNe were observed using the HST Wide Field Camera 3 infrared detector, with imaging in both wide- and medium-band filters. We demonstrate that the classification and redshift estimates are significantly improved by the inclusion of single-epoch medium-band observations. This medium-band imaging approximates a very low resolution spectrum (λ/Δλ ≲ 100) which can isolate broad spectral absorption features that differentiate SNe Ia from their most common core collapse cousins. This medium-band method is also insensitive to dust extinction and (unlike grism spectroscopy) it is not affected by contamination from the SN host galaxy or other nearby sources. As such, it can provide a more efficient—though less precise—alternative to IR spectroscopy for high-z SNe.

  13. TWO SNe Ia AT REDSHIFT ∼2: IMPROVED CLASSIFICATION AND REDSHIFT DETERMINATION WITH MEDIUM-BAND INFRARED IMAGING

    SciTech Connect

    Rodney, Steven A.; Riess, Adam G.; Jones, David O.; Scolnic, Daniel M.; Hemmati, Shoubaneh; Mobasher, Bahram; Molino, Alberto; McCully, Curtis; Strolger, Louis-Gregory; Casertano, Stefano; Graur, Or; Hayden, Brian

    2015-11-15

    We present two supernovae (SNe) discovered with the Hubble Space Telescope (HST) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, an HST multi-cycle treasury program. We classify both objects as SNe Ia and find redshifts of z = 1.80 ± 0.02 and 2.26{sup +0.02}{sub −0.10}, the latter of which is the highest redshift SN Ia yet seen. Using light curve fitting we determine luminosity distances and find that both objects are consistent with a standard ΛCDM cosmological model. These SNe were observed using the HST Wide Field Camera 3 infrared detector, with imaging in both wide- and medium-band filters. We demonstrate that the classification and redshift estimates are significantly improved by the inclusion of single-epoch medium-band observations. This medium-band imaging approximates a very low resolution spectrum (λ/Δλ ≲ 100) which can isolate broad spectral absorption features that differentiate SNe Ia from their most common core collapse cousins. This medium-band method is also insensitive to dust extinction and (unlike grism spectroscopy) it is not affected by contamination from the SN host galaxy or other nearby sources. As such, it can provide a more efficient—though less precise—alternative to IR spectroscopy for high-z SNe.

  14. DAO Spectroscopic classification of SN 2016bkr in 2MASS J11032043+7153141

    NASA Astrophysics Data System (ADS)

    Balam, D. D.; Graham, M. L.

    2016-04-01

    A spectrum was obtained of SN 2016bkr (ATEL #8857) on Apr. 8.41 UT using the 1.82-m Plaskett telescope (National Research Council of Canada) covering the range 385-710 nm (resolution 0.32 nm). Cross-correlation with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows 2016bkr to be a peculiar type-Ia supernova approximately 12 days post-maximum light.

  15. The Best and the Brightest: Tidal Disruption Events Discovered by ASAS-SN

    NASA Astrophysics Data System (ADS)

    Warren-Son Holoien, Thomas; ASAS-SN

    2016-01-01

    Even today only human eyes scan the entire optical sky for the violent, variable, and transient events that shape our universe. The All-Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin") is changing this by monitoring the visible sky to 17th magnitude every 2-3 days using multiple telescopes in the northern and southern hemispheres. Having been in operation for two years, ASAS-SN is discovering new transient objects daily, and while the primary goal of ASAS-SN is a complete survey of bright, nearby supernovae, ASAS-SN also discovers many other interesting nearby transients. Notably, ASAS-SN has discovered three bright tidal disruption events (TDEs), the three closest such events ever discovered at optical wavelengths, providing the opportunity to obtain detailed follow-up data at many wavelengths. ASAS-SN is discovering roughly 1 TDE for every 60 Type Ia supernovae, a rate that is significantly higher than other surveys. By virtue of their brightness, TDEs discovered by ASAS-SN can also be studied in unprecedented detail for many months, allowing deeper insight into their physics.

  16. The X-ray/radio and UV luminosity expected from symbiotic systems as the progenitor of SNe Ia

    NASA Astrophysics Data System (ADS)

    Meng, Xiangcun; Han, Zhanwen

    2016-04-01

    Context. Symbiotic systems (i.e. a white dwarf + red giant star, WD + RG), which experience mass loss and form circumstellar material (CSM), have been suggested as being a possible progenitor system of type Ia supernovae (SNe Ia). After a supernova explosion, the supernova ejecta may interact with the CSM or the RG secondary. X-ray/radio emission (excess UV photons) is expected from the interaction between supernova ejecta and the CSM (RG secondary). However, no X-ray or radio emission that has originated from this type of system has been observationally detected, and only four SNe Ia have shown any possible signal of excess UV emission. These observational discrepancies need to be interpreted. Aims: We seek to determine the luminosity of these emissions, using detailed binary evolution algorithms to obtain the parameters of binary systems at the moment of the supernova explosion. Methods: We carried out a series of binary stellar evolution calculations, in which the effect of tidally enhanced wind on the evolution of WD + RG systems is incorporated. The WDs increase their mass to the Chandrasekhar mass limit, and then explode as SNe Ia. Based on the binary evolution results, we estimated the X-ray/radio (the excess UV) luminosity from the interactions between supernova ejecta and the CSM (the secondary) using a variety of published standard models. Results: We found that the X-ray flux may be high enough to be detected for a nearby SN Ia from a symbiotic system, while the radio flux is more likely to de detected when the companion is an asymptotic giant branch (AGB) star, and for a first giant branch (FGB) companion, the radio flux is generally lower than the detection limit. For two well observed SNe Ia, 2011fe and 2014J, almost all symbiotic systems are excluded by X-ray observations, but WD + FGB systems may not be ruled out by radio observations. The excess UV luminosity that results from the collision of supernova ejecta with the RG secondary may be high

  17. 78 FR 48762 - Iowa Disaster #IA-00053

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00053 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This...: Submit completed loan applications to: U.S. Small Business Administration, Processing and...

  18. 76 FR 54521 - Iowa Disaster #IA-00036

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00036 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major ] disaster for Public Assistance Only for...

  19. 75 FR 53006 - Iowa Disaster #IA-00026

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only...

  20. 78 FR 28939 - Iowa Disaster #IA-00050

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  1. 76 FR 54522 - Iowa Disaster #IA-00037

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  2. 75 FR 47035 - Iowa Disaster # IA-00026

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for...

  3. 75 FR 10329 - Iowa Disaster #IA-00022

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-05

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00022 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  4. 75 FR 11582 - IOWA Disaster # IA-00023

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION IOWA Disaster IA-00023 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  5. 75 FR 45681 - Iowa Disaster #IA-00025

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-03

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  6. 78 FR 36010 - Iowa Disaster #IA-00052

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00052 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  7. 76 FR 52042 - Iowa Disaster #IA-00035

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-19

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00035 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa Dated....

  8. 76 FR 27738 - Iowa Disaster #IA-00030

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00030 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa dated...

  9. 76 FR 55721 - Iowa Disaster #IA-00038

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-08

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00038 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  10. 76 FR 66768 - Iowa Disaster #IA-00033

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-27

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00033 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Iowa...

  11. 78 FR 42147 - Iowa Disaster #IA-00054

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Iowa Disaster IA-00054 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for...

  12. Calculating Pre-SN Mass-Loss Histories from Post-Explosion Observations and the Special Case of SN 2006gy

    NASA Astrophysics Data System (ADS)

    Fox, Ori D.

    2015-08-01

    A growing number of SNe now show evidence for significant interaction between the forward shock and a pre-existing circumstellar medium (CSM) formed by the pre-SN mass-loss. The SN community likes to argue that it can indirectly constrain the progenitor systems for these SNe by measuring the wind speeds, densities, compositions, and asymmetries of the CSM. The measurements, however, rely on a number of assumptions and can result in degeneracies that straddle the divide between RSGs and more massive stars. Furthermore, the implications of the measured properties may sometimes be simplified to fit a SN expert's relatively basic understanding of stellar wind parameters. Given the opportunity to have experts in massive stars, cool stars, and supernovae together in the same room, I thought it would be a good opportunity to review the different methods employed by the SN community to measure mass-loss rates. I will then provide an update from a recent Spitzer survey on the measured CSM properties from different subclasses of SNe with known shock interaction (including SLSNe, SNe II, IIn, Ibc, and even Ia-CSM). Finally, I will present new HST data on the SLSN Type IIn SN 2006gy and discuss the implications on the progenitor system and pre-SN mass-loss.

  13. Persistent C II absorption in the normal type Ia supernova 2002fk

    SciTech Connect

    Cartier, Régis; Zelaya, Paula; Hamuy, Mario; Maza, José; González, Luis; Huerta, Leonor; Pignata, Giuliano; Förster, Francisco; Folatelli, Gaston; Phillips, Mark M.; Morrell, Nidia; Contreras, Carlos; Roth, Miguel; González, Sergio; Clocchiatti, Alejandro; Coppi, Paolo; Koviak, Kathleen

    2014-07-01

    We present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from –4 to +95 days since maximum. Our observations show the presence of C II lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s{sup –1} and persisting until 8 days past maximum light with a velocity of ∼9000 km s{sup –1}. SN 2002fk is characterized by a small velocity gradient of v-dot {sub Si} {sub II}=26 km s{sup –1} day{sup –1}, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C II in the early-time spectrum suggests that the observation of C II could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H {sub 0} value based on near-infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s{sup –1} Mpc{sup –1}, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%-9%) H {sub 0} values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H {sub 0}.

  14. A threat-based definition of IA- and IA-enabled products.

    SciTech Connect

    Shakamuri, Mayuri; Schaefer, Mark A.; Campbell, Philip LaRoche

    2010-07-01

    This paper proposes a definition of 'IA and IA-enabled products' based on threat, as opposed to 'security services' (i.e., 'confidentiality, authentication, integrity, access control or non-repudiation of data'), as provided by Department of Defense (DoD) Instruction 8500.2, 'Information Assurance (IA) Implementation.' The DoDI 8500.2 definition is too broad, making it difficult to distinguish products that need higher protection from those that do not. As a consequence the products that need higher protection do not receive it, increasing risk. The threat-based definition proposed in this paper solves those problems by focusing attention on threats, thereby moving beyond compliance to risk management. (DoDI 8500.2 provides the definitions and controls that form the basis for IA across the DoD.) Familiarity with 8500.2 is assumed.

  15. A threat-based definition of IA and IA-enabled products.

    SciTech Connect

    Shakamuri, Mayuri; Schaefer, Mark A.; Campbell, Philip LaRoche

    2010-09-01

    This paper proposes a definition of 'IA and IA-enabled products' based on threat, as opposed to 'security services' (i.e., 'confidentiality, authentication, integrity, access control or non-repudiation of data'), as provided by Department of Defense (DoD) Instruction 8500.2, 'Information Assurance (IA) Implementation.' The DoDI 8500.2 definition is too broad, making it difficult to distinguish products that need higher protection from those that do not. As a consequence the products that need higher protection do not receive it, increasing risk. The threat-based definition proposed in this paper solves those problems by focusing attention on threats, thereby moving beyond compliance to risk management. (DoDI 8500.2 provides the definitions and controls that form the basis for IA across the DoD.) Familiarity with 8500.2 is assumed.

  16. Expression of I-A and I-E,C region-coded Ia antigens on functional B cell subpopulations.

    PubMed

    Frelinger, J A; Hibbler, F J; Hill, S W

    1978-12-01

    Ia antigens from specific subregions have been examined on functional B cell populations. Expression of both I-A and I-E,C region antigens was demonstrated on cells required for both lipopolysaccharide mitogenesis and polyclonal activation. Similar I-A and I-E,C subregion expression was found on cells required for response to the T-independent antigen, polyvinylpyrrolidone. TNP-specific IgM and hen egg lysozyme-specific IgG plaque-forming cells also express I-A and I-E,C region antigens. No evidence was found for an Ia- population responsive in the systems tested. Further, no evidence of preferential expression of I-A or I-E,C region antigens was observed in any system examined. Therefore, it appears that B cells express both I-A and I-E,C region-coded Ia antigens.

  17. EARLY- AND LATE-TIME OBSERVATIONS OF SN 2008ha: ADDITIONAL CONSTRAINTS FOR THE PROGENITOR AND EXPLOSION

    SciTech Connect

    Foley, Ryan J.; Challis, Peter J.; Kirshner, Robert P.; Brown, Peter J.; Rest, Armin; Wood-Vasey, W. Michael

    2010-01-01

    We present a new maximum-light optical spectrum of the extremely low luminosity and exceptionally low-energy Type Ia supernova (SN Ia) 2008ha, obtained one week before the earliest published spectrum. Previous observations of SN 2008ha were unable to distinguish between a massive star and white dwarf (WD) origin for the SN. The new maximum-light spectrum, obtained one week before the earliest previously published spectrum, unambiguously shows features corresponding to intermediate mass elements, including silicon, sulfur, and carbon. Although strong silicon features are seen in some core-collapse SNe, sulfur features, which are a signature of carbon/oxygen burning, have always been observed to be weak in such events. It is therefore likely that SN 2008ha was the result of a thermonuclear explosion of a carbon-oxygen WD. Carbon features at maximum light show that unburned material is present to significant depths in the SN ejecta, strengthening the case that SN 2008ha was a failed deflagration. We also present late-time imaging and spectroscopy that are consistent with this scenario.

  18. The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Sullivan, M.; Astier, P.; Balam, D.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Guy, J.; Hook, I.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aubourg, E.; Bronder, J.; Ellis, R. S.; Fabbro, S.; Filiol, M.; Le Borgne, D.; Palanque-Delabrouille, N.; Perlmutter, S.; Ripoche, P.

    2006-10-01

    We compare the rise times of nearby and distant Type Ia supernovae (SNe Ia) as a test for evolution using 73 high-redshift spectroscopically confirmed SNe Ia from the first 2 years of the 5 year Supernova Legacy Survey (SNLS) and published observations of nearby SNe. Because of the ``rolling'' search nature of the SNLS, our measurement is approximately 6 times more precise than previous studies, allowing for a more sensitive test of evolution between nearby and distant SNe. Adopting a simple t2 early-time model (as in previous studies), we find that the rest-frame B rise times for a fiducial SN Ia at high and low redshift are consistent, with values 19.10+0.18-0.17(stat)+/-0.2(syst) and 19.58+0.22-0.19 days, respectively; the statistical significance of this difference is only 1.4 σ. The errors represent the uncertainty in the mean rather than any variation between individual SNe. We also compare subsets of our high-redshift data set based on decline rate, host galaxy star formation rate, and redshift, finding no substantive evidence for any subsample dependence. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS.

  19. TIDAL TAIL EJECTION AS A SIGNATURE OF TYPE Ia SUPERNOVAE FROM WHITE DWARF MERGERS

    SciTech Connect

    Raskin, Cody; Kasen, Daniel

    2013-07-20

    The merger of two white dwarfs may be preceded by the ejection of some mass in ''tidal tails,'' creating a circumstellar medium around the system. We consider the variety of observational signatures from this material, which depend on the lag time between the start of the merger and the ultimate explosion (assuming one occurs) of the system in a Type Ia supernova (SN Ia). If the time lag is fairly short, then the interaction of the supernova ejecta with the tails could lead to detectable shock emission at radio, optical, and/or X-ray wavelengths. At somewhat later times, the tails produce relatively broad NaID absorption lines with velocity widths of the order of the white dwarf escape speed ({approx}1000 km s{sup -1}). That none of these signatures have been detected in normal SNe Ia constrains the lag time to be either very short ({approx}< 100 s) or fairly long ({approx}> 100 yr). If the tails have expanded and cooled over timescales {approx}10{sup 4} yr, then they could be observable through narrow NaID and Ca II H and K absorption lines in the spectra, which are seen in some fraction of SNe Ia. Using a combination of three-dimensional and one-dimensional hydrodynamical codes, we model the mass loss from tidal interactions in binary systems, and the subsequent interactions with the interstellar medium, which produce a slow-moving, dense shell of gas. We synthesize NaID line profiles by ray casting through this shell, and show that in some circumstances tidal tails could be responsible for narrow absorptions similar to those observed.

  20. Probing the Isotropy of Cosmic Acceleration Traced By Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Javanmardi, B.; Porciani, C.; Kroupa, P.; Pflamm-Altenburg, J.

    2015-09-01

    We present a method to test the isotropy of the magnitude-redshift relation of Type Ia Supernovae (SNe Ia) and single out the most discrepant direction (in terms of the signal-to-noise ratio) with respect to the all-sky data. Our technique accounts for possible directional variations of the corrections for SNe Ia and yields all-sky maps of the best-fit cosmological parameters with arbitrary angular resolution. To show its potential, we apply our method to the high-redshift SNe Ia from the recent Union2.1 compilation, building maps with three different angular resolutions. We use a Monte Carlo method to estimate the statistical significance with which we could reject the null hypothesis that the magnitude-redshift relation is isotropic based on the properties of the observed most discrepant directions. We find that, based on pure signal-to-noise arguments, the null hypothesis cannot be rejected at any meaningful confidence level. However, if we also consider that the strongest deviations in the Union2.1 sample closely align with the dipole temperature anisotropy of the cosmic microwave background, we find that the null hypothesis should be rejected at the 95%-99% confidence level, slightly depending on the angular resolution of the study. If this result is not due to a statistical fluke, it might either indicate that the SN data have not been cleaned from all possible systematics or even point toward new physics. We finally discuss future perspectives in the field for achieving larger and more uniform data sets that will vastly improve the quality of the results and optimally exploit our method.

  1. PROBING THE ISOTROPY OF COSMIC ACCELERATION TRACED BY TYPE Ia SUPERNOVAE

    SciTech Connect

    Javanmardi, B.; Porciani, C.; Kroupa, P.; Pflamm-Altenburg, J.

    2015-09-01

    We present a method to test the isotropy of the magnitude–redshift relation of Type Ia Supernovae (SNe Ia) and single out the most discrepant direction (in terms of the signal-to-noise ratio) with respect to the all-sky data. Our technique accounts for possible directional variations of the corrections for SNe Ia and yields all-sky maps of the best-fit cosmological parameters with arbitrary angular resolution. To show its potential, we apply our method to the high-redshift SNe Ia from the recent Union2.1 compilation, building maps with three different angular resolutions. We use a Monte Carlo method to estimate the statistical significance with which we could reject the null hypothesis that the magnitude–redshift relation is isotropic based on the properties of the observed most discrepant directions. We find that, based on pure signal-to-noise arguments, the null hypothesis cannot be rejected at any meaningful confidence level. However, if we also consider that the strongest deviations in the Union2.1 sample closely align with the dipole temperature anisotropy of the cosmic microwave background, we find that the null hypothesis should be rejected at the 95%–99% confidence level, slightly depending on the angular resolution of the study. If this result is not due to a statistical fluke, it might either indicate that the SN data have not been cleaned from all possible systematics or even point toward new physics. We finally discuss future perspectives in the field for achieving larger and more uniform data sets that will vastly improve the quality of the results and optimally exploit our method.

  2. Type Ia supernovae from violent mergers of carbon-oxygen white dwarfs: polarization signatures

    NASA Astrophysics Data System (ADS)

    Bulla, M.; Sim, S. A.; Pakmor, R.; Kromer, M.; Taubenberger, S.; Röpke, F. K.; Hillebrandt, W.; Seitenzahl, I. R.

    2016-01-01

    The violent merger of two carbon-oxygen white dwarfs has been proposed as a viable progenitor for some Type Ia supernovae. However, it has been argued that the strong ejecta asymmetries produced by this model might be inconsistent with the low degree of polarization typically observed in Type Ia supernova explosions. Here, we test this claim by carrying out a spectropolarimetric analysis for the model proposed by Pakmor et al. for an explosion triggered during the merger of a 1.1 and 0.9 M⊙ carbon-oxygen white dwarf binary system. Owing to the asymmetries of the ejecta, the polarization signal varies significantly with viewing angle. We find that polarization levels for observers in the equatorial plane are modest (≲1 per cent) and show clear evidence for a dominant axis, as a consequence of the ejecta symmetry about the orbital plane. In contrast, orientations out of the plane are associated with higher degrees of polarization and departures from a dominant axis. While the particular model studied here gives a good match to highly polarized events such as SN 2004dt, it has difficulties in reproducing the low polarization levels commonly observed in normal Type Ia supernovae. Specifically, we find that significant asymmetries in the element distribution result in a wealth of strong polarization features that are not observed in the majority of currently available spectropolarimetric data of Type Ia supernovae. Future studies will map out the parameter space of the merger scenario to investigate if alternative models can provide better agreement with observations.

  3. The Type Ia Supernova Rate in Redshift 0.5-0.9 Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Sharon, Keren; Gal-Yam, Avishay; Maoz, Dan; Filippenko, Alexei V.; Foley, Ryan J.; Silverman, Jeffrey M.; Ebeling, Harald; Ma, Cheng-Jiun; Ofek, Eran O.; Kneib, Jean-Paul; Donahue, Megan; Ellis, Richard S.; Freedman, Wendy L.; Kirshner, Robert P.; Mulchaey, John S.; Sarajedini, Vicki L.; Voit, G. Mark

    2010-08-01

    Supernova (SN) rates are potentially powerful diagnostics of metal enrichment and SN physics, particularly in galaxy clusters with their deep, metal-retaining potentials and relatively simple star formation histories. We have carried out a survey for SNe in galaxy clusters, at a redshift range of 0.5 < z < 0.9, using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. We reimaged a sample of 15 clusters that were previously imaged by ACS, thus obtaining two to three epochs per cluster in which we discovered five likely cluster SNe, six possible cluster Type Ia supernovae, two hostless SN candidates, and several background and foreground events. Keck spectra of the host galaxies were obtained to establish cluster membership. We conducted detailed efficiency simulations, and measured the stellar luminosities of the clusters using Subaru images. We derive a cluster SN rate of 0.35SNu B +0.17 -0.12(statistical) ±0.13(classification) ±0.01(systematic) (where SNu B = SNe (100 yr 1010 L B,sun)-1) and 0.112SNu M +0.055 -0.039(statistical) ±0.042(classification) ±0.005(systematic) (where SNu M = SNe (100 yr 1010 M sun)-1). As in previous measurements of cluster SN rates, the uncertainties are dominated by small-number statistics. The SN rate in this redshift bin is consistent with the SN rate in clusters at lower redshifts (to within the uncertainties), and shows that there is, at most, only a slight increase of cluster SN rate with increasing redshift. The low and fairly constant SN Ia rate out to z ≈ 1 implies that the bulk of the iron mass in clusters was already in place by z ≈ 1. The recently observed doubling of iron abundances in the intracluster medium between z = 1 and 0, if real, is likely to be the result of redistribution of existing iron, rather than new production of iron. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of

  4. Exploration of the interaction of type Ia supernovae with the circumstellar environment

    NASA Astrophysics Data System (ADS)

    Dragulin, Paul

    . The free parameters are: the a) mass loss dot{m}, b) wind velocity v_w, c) density distributions ∝ r. {-s} of theISM, and d)} the duration of the wind prior to the supernova explosion. I discuss the observational signatures with respect to light curves and high resolution spectra as tools to probe the environment of SNe˜Ia. The specific properties and evolution of the progenitor systems are found to leave unique imprints. During the progenitor evolution and with typical parameters in the SD scenario, the winds create a low density bubble surrounding the progenitor system and a high-density shell. It is also found that accretion disk winds dominate the environment formation. Within a distance of several light-years (ly), the densities are smaller by factors of 10. {2...4} compared to theenvironment. This explains the general lack of observed interaction in late time Supernova (SN) light curves for, at least, several years. The overdensities of the shells are between a factor of 4 to several hundred in case of constant density ISM and environments produced by stellar winds, respectively. The expansion velocity and width of the shell are typically 1-10 % of both v_w and the contact discontinuity R_C and may produce narrow spectral lines as observed in some SNe˜Ia. Typically, narrow circumstellar lines of equivalent width ≈ 100 m{Å are found for uniform ISM typical in Spiral galaxies and ≈ 1 m{Å} for wind environments. The outer layers of a SNe˜Ia expands with velocities of 10 to 30 % of the speed of light and we may expect some interaction with the shells several years after the explosion. I apply the analysis to SN2014J and discuss several scenarios. For SN˜2014J, the environment is likely formed by the AD wind running into a region produced by the Red Giant (RG) wind from the progenitor star prior to its WD stage. The delay times between the formation of the WD and the explosion is suggested to be short, ˜ 10. 5˜yr. Finally the same analysis is

  5. SN Typing for the SDSS SN Survey

    SciTech Connect

    Rivers, Elizabeth S.; /Wellesley Coll. /SLAC

    2005-12-15

    In the fall of 2004 the Sloan Digital Sky Survey (SDSS) 2.5m telescope scanned the southern equatorial stripe for approximately 20 nights over the space of two months. Light curves for over four dozen supernovae (SNe) were collected over time using five colored filters ugriz that together had a range of approximately 3000{angstrom} to 10500{angstrom}. 22 SNe were spectroscopically confirmed with follow-up observation. Using the data obtained in the Fall 2004 campaign, preparations are now being made for the Supernova Survey of the SDSS II, a three-year extension of the original project. One main goal of the Supernova Survey will be to identify and study type Ia SNe of up to redshift {approx}0.4, the intermediate ''redshift desert'', as well as enabling further study of other types of SNe including type 1b/c and peculiar SNe. Most of the SNe found will not have spectra taken, due to time and cost constraints. Thus it would be advantageous to be able to robustly type SNe solely from the light curves obtained by the SDSS telescope prior to, or even without ever obtaining a spectrum. Using light curves of well-observed SNe templates were constructed for comparison with unknown SNe in order to photometrically type them.

  6. THE INFRARED LIGHT CURVE OF SN 2011fe IN M101 AND THE DISTANCE TO M101

    SciTech Connect

    Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Binkert, W. S.; Butler, K.; Everett, M.; Wood-Vasey, W. M.; Adams, J. J.; Anderson, R. E.; Beck, T. L.; Bentz, M. C.; Bershady, M. A.; Eigenbrot, A.; Gallagher, J. S.; Camarata, M. A.; Garnavich, P. M.; Glikman, E.; Harbeck, D.; and others

    2012-07-20

    We present near-infrared light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting 14 days before maximum brightness in the B band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera. When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 {+-} 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depending on which absolute calibration for Type Ia SNe is used.

  7. Type Ia supernovae: their origin and possible applications in cosmology.

    PubMed

    Nomoto, K; Iwamoto, K; Kishimoto, N

    1997-05-30

    Spectroscopic and photometric evidence indicates that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs. However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial. The relatively uniform light curves and spectral evolution of SNe Ia have led to their use as a standard candle for determining cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Recent progress includes the calibration of the absolute maximum brightness of SNe Ia with the Hubble Space Telescope, the reduction of the dispersion in the Hubble diagram through the use of the relation between the light curve shape and the maximum brightness of SNe Ia, and the discovery of many SNe Ia with high red shifts. PMID:9190677

  8. Type Ia supernovae: their origin and possible applications in cosmology.

    PubMed

    Nomoto, K; Iwamoto, K; Kishimoto, N

    1997-05-30

    Spectroscopic and photometric evidence indicates that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs. However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial. The relatively uniform light curves and spectral evolution of SNe Ia have led to their use as a standard candle for determining cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Recent progress includes the calibration of the absolute maximum brightness of SNe Ia with the Hubble Space Telescope, the reduction of the dispersion in the Hubble diagram through the use of the relation between the light curve shape and the maximum brightness of SNe Ia, and the discovery of many SNe Ia with high red shifts.

  9. A SPECTROPOLARIMETRIC VIEW ON THE NATURE OF THE PECULIAR TYPE I SN 2005hk

    SciTech Connect

    Maund, Justyn R.; Wheeler, J. Craig; Wang, Lifan; Baade, Dietrich; Patat, Ferdinando; Clocchiatti, Alejandro; Quinn, Jason; Zelaya, Paula; Hoeflich, Peter E-mail: wheel@astro.as.utexas.ed E-mail: dbaade@eso.or E-mail: aclocchi@astro.puc.c E-mail: pazelaya@astro.puc.c

    2010-10-20

    We report two spectropolarimetric observations of SN 2005hk, which is a close copy of the 'very peculiar' SN 2002cx, showing low peak luminosity, slow decline, high ionization near peak, and an unusually low expansion velocity of only about 7000 km s{sup -1}. Further to the data presented by Chornock et al., at -4 days before maximum, we present data of this object taken on 2005 November 9 (near maximum) and November 23 (+ 2 weeks) that show the continuum and most of the spectral lines to be polarized at levels of about 0.2%-0.3%. At both epochs the data correspond to the Spectropolarimetric Type D1. The general low level of line polarization suggests that the line-forming regions for most species observed in the spectrum have a similar shape to that of the photosphere, which deviates from a spherical symmetry by <10%. In comparison with spectropolarimetry of Type Ia and core-collapse SNe at similar epochs, we find that the properties of SN 2005hk are most similar to those of Type Ia SNe. In particular, we find the low levels of continuum and line polarization to indicate that the explosion mechanism is approximately spherical, with homogeneous ejecta (unlike the chemically segregated ejecta of CCSNe). We discuss the possibility that SN 2005hk was the result of the pure deflagration of a white dwarf and note the issues concerning this interpretation.

  10. Systematic uncertainties associated with the cosmological analysis of the first Pan-STARRS1 type Ia supernova sample

    SciTech Connect

    Scolnic, D.; Riess, A.; Brout, D.; Rodney, S.; Rest, A.; Huber, M. E.; Tonry, J. L.; Foley, R. J.; Chornock, R.; Berger, E.; Soderberg, A. M.; Stubbs, C. W.; Kirshner, R. P.; Challis, P.; Czekala, I.; Drout, M.; Narayan, G.; Smartt, S. J.; Botticella, M. T.; Schlafly, E.; and others

    2014-11-01

    We probe the systematic uncertainties from the 113 Type Ia supernovae (SN Ia) in the Pan-STARRS1 (PS1) sample along with 197 SN Ia from a combination of low-redshift surveys. The companion paper by Rest et al. describes the photometric measurements and cosmological inferences from the PS1 sample. The largest systematic uncertainty stems from the photometric calibration of the PS1 and low-z samples. We increase the sample of observed Calspec standards from 7 to 10 used to define the PS1 calibration system. The PS1 and SDSS-II calibration systems are compared and discrepancies up to ∼0.02 mag are recovered. We find uncertainties in the proper way to treat intrinsic colors and reddening produce differences in the recovered value of w up to 3%. We estimate masses of host galaxies of PS1 supernovae and detect an insignificant difference in distance residuals of the full sample of 0.037 ± 0.031 mag for host galaxies with high and low masses. Assuming flatness and including systematic uncertainties in our analysis of only SNe measurements, we find w =−1.120{sub −0.206}{sup +0.360}(Stat){sub −0.291}{sup +0.269}(Sys). With additional constraints from Baryon acoustic oscillation, cosmic microwave background (CMB) (Planck) and H {sub 0} measurements, we find w=−1.166{sub −0.069}{sup +0.072} and Ω{sub m}=0.280{sub −0.012}{sup +0.013} (statistical and systematic errors added in quadrature). The significance of the inconsistency with w = –1 depends on whether we use Planck or Wilkinson Microwave Anisotropy Probe measurements of the CMB: w{sub BAO+H0+SN+WMAP}=−1.124{sub −0.065}{sup +0.083}.

  11. The Golden Standard Type Ia Supernova 2005cf: Observations from the Ultraviolet to the Near-Infrared Wavebands

    NASA Astrophysics Data System (ADS)

    Wang, X.; Li, W.; Filippenko, A. V.; Foley, R. J.; Kirshner, R. P.; Modjaz, M.; Bloom, J.; Brown, P. J.; Carter, D.; Friedman, A. S.; Gal-Yam, A.; Ganeshalingam, M.; Hicken, M.; Krisciunas, K.; Milne, P.; Silverman, J. M.; Suntzeff, N. B.; Wood-Vasey, W. M.; Cenko, S. B.; Challis, P.; Fox, D. B.; Kirkman, D.; Li, J. Z.; Li, T. P.; Malkan, M. A.; Moore, M. R.; Reitzel, D. B.; Rich, R. M.; Serduke, F. J. D.; Shang, R. C.; Steele, T. N.; Swift, B. J.; Tao, C.; Wong, D. S.; Zhang, S. N.

    2009-05-01

    We present extensive photometry at ultraviolet (UV), optical, and near-infrared (NIR) wavelengths, as well as dense sampling of optical spectra, for the normal Type Ia supernova (SN Ia) 2005cf. The optical photometry, performed at eight different telescopes, shows a 1σ scatter of lsim0.03 mag after proper corrections for the instrument responses. From the well-sampled light curves, we find that SN 2005cf reached a B-band maximum at 13.63 ± 0.02 mag, with an observed luminosity decline rate Δm 15(B) = 1.05 ± 0.03 mag. The correlations between the decline rate and various color indexes, recalibrated on the basis of an expanded SN Ia sample, yield a consistent estimate for the host-galaxy reddening of SN 2005cf, E(B - V)host = 0.10 ± 0.03 mag. The UV photometry was obtained with the Hubble Space Telescope and the Swift Ultraviolet/Optical Telescope, and the results match each other to within 0.1-0.2 mag. The UV light curves show similar evolution to the broadband U, with an exception in the 2000-2500 Å spectral range (corresponding to the F220W/uvm2 filters), where the light curve appears broader and much fainter than that on either side (likely owing to the intrinsic spectral evolution). Combining the UV data with the ground-based optical and NIR data, we establish the generic UV-optical-NIR bolometric light curve for SN 2005cf and derive the bolometric corrections in the absence of UV and/or NIR data. The overall spectral evolution of SN 2005cf is similar to that of a normal SN Ia, but with variety in the strength and profile of the main feature lines. The spectra at early times displayed strong, high-velocity (HV) features in the Ca II H&K doublet and NIR triplet, which were distinctly detached from the photosphere (v ≈ 10,000 km s-1) at a velocity ranging from 20,000 to 25,000 km s-1. One interesting feature is the flat-bottomed absorption observed near 6000 Å in the earliest spectrum, which rapidly evolved into a triangular shape and then became a normal

  12. The Local Type Ia Supernova Progenitors: One Double-Degenerate, No Symbiotics

    NASA Astrophysics Data System (ADS)

    Pagnotta, Ashley; Schaefer, B. E.

    2012-01-01

    Although the basic mechanism responsible for Type Ia supernovae appears to be well understood (thermonuclear explosion of a carbon-oxygen white dwarf that has reached the Chandrasekhar mass limit), the identity of the progenitor system(s) remains a mystery. With implications from stellar evolution to frontline cosmology, it is critical to attack this problem from every possible angle. We present results from our study of three known historical Ia supernovae in the Large Magellanic Cloud (LMC) which allow us to eliminate possible progenitor candidates for at least the local population. We used archival Hubble Space Telescope images of SNR 0509-67.5, SNR 0509-68.7, and SNR 0519-69.0 to determine the site of each explosion and then search the surrounding area for potential ex-companion stars that were left behind. The search was carried out within an error ellipse that accounts for measurement error on the geometric center of the remnant, the orbital velocity of the pre-supernova binary system, and kicks from the actual explosion. For SNR 0509-67.5, the error ellipse is empty to the HST 5σ limiting magnitude of V=26.9. Using an LMC distance modulus of 18.5, this implies that any single degenerate ex-companion must be fainter than MV=+8.4 (corresponding approximately to a K9 main sequence star), which eliminates all currently-published single-degenerate models and leads us to conclude that this system had a double-degenerate (double white dwarf) progenitor. For SNR 0509-68.7 and SNR 0519-69.0, we can eliminate the possibility of red giant and subgiant ex-companions. It has been shown that the two confident galactic Ia supernovae (Tycho's SN 1572 and SN 1006) also do not have red giant ex-companion stars. Combined with our three systems, this eliminates the symbiotic progenitor channel for all of the nearby Ia supernovae. This work was supported by the National Science Foundation (AST-1109420).

  13. Radiation Transport in Type IA Supernovae

    SciTech Connect

    Eastman, R

    1999-11-16

    It has been said more than once that the critical link between explosion models and observations is the ability to accurately simulate cooling and radiation transport in the expanding ejecta of Type Ia supernovae. It is perhaps frustrating to some of the theorists who study explosion mechanisms, and to some of the observers too, that more definitive conclusions have not been reached about the agreement, or lack thereof, between various Type Ia supernova models and the data. Although claims of superlative accuracy in transport simulations are sometimes made, I will argue here that there are outstanding issues of critical importance and in need of addressing before radiation transport calculations are accurate enough to discriminate between subtly different explosion models.

  14. Genetic algorithms and supernovae type Ia analysis

    SciTech Connect

    Bogdanos, Charalampos; Nesseris, Savvas E-mail: nesseris@nbi.dk

    2009-05-15

    We introduce genetic algorithms as a means to analyze supernovae type Ia data and extract model-independent constraints on the evolution of the Dark Energy equation of state w(z) {identical_to} P{sub DE}/{rho}{sub DE}. Specifically, we will give a brief introduction to the genetic algorithms along with some simple examples to illustrate their advantages and finally we will apply them to the supernovae type Ia data. We find that genetic algorithms can lead to results in line with already established parametric and non-parametric reconstruction methods and could be used as a complementary way of treating SNIa data. As a non-parametric method, genetic algorithms provide a model-independent way to analyze data and can minimize bias due to premature choice of a dark energy model.

  15. Late-time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Nugent, Peter E.; Gal-Yam, Avishay; Sullivan, Mark; Howell, D. Andrew; Filippenko, Alexei V.; Pan, Yen-Chen; Cenko, S. Bradley; Hook, Isobel M.

    2013-08-01

    PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption features, including saturated Ca II H and K lines that weakened and eventually went into emission. The strength of the emission component of Hα gradually increased, implying that the SN was undergoing significant interaction with its circumstellar medium (CSM). These features, and many others, were blueshifted slightly and showed a P-Cygni profile, likely indicating that the CSM was directly related to, and probably previously ejected by, the progenitor system itself. These and other observations led Dilday et al. to conclude that PTF11kx came from a symbiotic nova progenitor like RS Oph. In this work we extend the spectral coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. The late-time spectra of PTF11kx are dominated by Hα emission (with widths of full width at half-maximum intensity ≈2000 km s-1), strong Ca II emission features (~10,000 km s-1 wide), and a blue "quasi-continuum" due to many overlapping narrow lines of Fe II. Emission from oxygen, He I, and Balmer lines higher than Hα is weak or completely absent at all epochs, leading to large observed Hα/Hβ intensity ratios. The Hα emission appears to increase in strength with time for ~1 yr, but it subsequently decreases significantly along with the Ca II emission. Our latest spectrum also indicates the possibility of newly formed dust in the system as evidenced by a slight decrease in the red wing of Hα. During the same epochs, multiple narrow emission features from the CSM temporally vary in strength. The weakening of the Hα and Ca II emission at late times is possible evidence that the SN ejecta have overtaken the majority of the CSM and agrees with models of other strongly interacting SNe Ia. The varying narrow emission features, on the other hand, may indicate that the CSM is clumpy or consists of multiple thin shells.

  16. TR-IA payload recovery system

    NASA Astrophysics Data System (ADS)

    Kochiyama, Jiro; Kinai, Shigeki; Morita, Shinya

    The TR-IA microgravity-experimentation sounding rocket baseline configuration and recovery system are presented. Aerodynamic braking is incorporated through the requisite positioning of the reentry-body center of gravity. The recovery sequence is initiated by baroswitches, which eject the pilot chute. Even in the event of flotation bag malfunction, the structure containing the experiment is watertight. An account is given of the nature and the results of the performance tests conducted to establish the soundness of various materials and components.

  17. Type Ia Supernova Models and Progenitor Scenarios

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Kamiya, Yasuomi; Nakasato, Naohito

    2013-01-01

    We review some recent developments in theoretical studies on the connection between the progenitor systems of Type Ia supernovae (SNe Ia) and the explosion mechanisms. (1) DD-subCh: In the merging of double C+O white dwarfs (DD scenario), if the carbon detonation is induced near the white dwarf (WD) surface in the early dynamical phase, it could result in the (effectively) sub-Chandrasekhar mass explosion. (2) DD-Ch: If no surface C-detonation is ignited, the WD could grow until the Chandrasekhar mass is reached, but the outcome depends on whether the quiescent carbon shell burning is ignited and burns C+O into O+Ne+Mg. (3) SD-subCh: In the single degenerate (SD) scenario, if the He shell-flashes grow strong to induce a He detonation, it leads to the sub-Chandra explosion. (4) SD-Ch: If the He-shell flashes are not strong enough, they still produce interesting amounts of Si and S near the surface of the C+O WD before the explosion. In the Chandra mass explosion, the central density is high enough to produce electron capture elements, e.g., stable 58Ni. Observations of the emission lines of Ni in the nebular spectra provides useful diagnostics of the sub-Chandra vs. Chandra issue. The recent observations of relatively low velocity carbon near the surface of SNe Ia provide also an interesting constraint on the explosion models.

  18. Modulation of macrophage Ia expression by lipopolysaccharide: Stem cell requirements, accessory lymphocyte involvement, and IA-inducing factor production

    SciTech Connect

    Wentworth, P.A.; Ziegler, H.K.

    1989-07-01

    The mechanism of induction of murine macrophage Ia expression by lipopolysaccharide (LPS) was studied. Intraperitoneal injection of 1 microgram of LPS resulted in a 3- to 10-fold increase in the number of IA-positive peritoneal macrophages (flow cytometry and immunofluorescence) and a 6-to 16-fold increase by radioimmunoassay. The isolated lipid A moiety of LPS was a potent inducer of macrophage Ia expression. Ia induction required a functional myelopoietic system as indicated by the finding that the response to LPS was eliminated in irradiated (900 rads) mice and reinstated by reconstitution with bone marrow cells. Comparison of LPS-induced Ia expression in normal and LPS-primed mice revealed a faster secondary response to LPS. The memory response could be adoptively transferred to normal mice with nonadherent spleen cells prepared 60 days after LPS injection. Spleen cells prepared 5 days after LPS injection caused Ia induction in LPS-nonresponder mice; such induction was not observed in irradiated (900 rads) recipients. The cell responsible for this phenomenon was identified as a Thy-1+, immunoglobulin-negative nonadherent cell. The biosynthesis and expression of Ia were not increased by direct exposure of macrophages to LPS in vitro. Small amounts of LPS inhibited Ia induction by gamma interferon. LPS showed positive regulatory effects on Ia expression by delaying the loss of Ia expression on cultured macrophages and by stimulating the production of Ia-inducing factors. Supernatants from cultured spleen cells stimulated with LPS in vitro contained antiviral and Ia-inducing activity that was acid labile, indicating that the active factor is gamma interferon. We conclude that induction of Ia expression by LPS in vivo is a bone-marrow-dependent, radiation-sensitive process which involves the stimulation of a gamma interferon-producing accessory lymphocyte and a delay in Ia turnover.

  19. EVLA OBSERVATIONS CONSTRAIN THE ENVIRONMENT AND PROGENITOR SYSTEM OF Type Ia SUPERNOVA 2011fe

    SciTech Connect

    Chomiuk, Laura; Soderberg, Alicia M.; Moe, Maxwell; Margutti, Raffaella; Fong, Wen-fai; Dittmann, Jason A.; Chevalier, Roger A.; Rupen, Michael P.; Badenes, Carles; Fransson, Claes

    2012-05-10

    We report unique Expanded Very Large Array observations of SN 2011fe representing the most sensitive radio study of a Type Ia supernova to date. Our data place direct constraints on the density of the surrounding medium at radii {approx}10{sup 15}-10{sup 16} cm, implying an upper limit on the mass loss rate from the progenitor system of M-dot < or approx. 6 x 10{sup -10} M{sub Sun} yr{sup -1} (assuming a wind speed of 100 km s{sup -1}) or expansion into a uniform medium with density n{sub CSM} {approx}< 6 cm{sup -3}. Drawing from the observed properties of non-conservative mass transfer among accreting white dwarfs, we use these limits on the density of the immediate environs to exclude a phase space of possible progenitor systems for SN 2011fe. We rule out a symbiotic progenitor system and also a system characterized by high accretion rate onto the white dwarf that is expected to give rise to optically thick accretion winds. Assuming that a small fraction, 1%, of the mass accreted is lost from the progenitor system, we also eliminate much of the potential progenitor parameter space for white dwarfs hosting recurrent novae or undergoing stable nuclear burning. Therefore, we rule out much of the parameter space associated with popular single degenerate progenitor models for SN 2011fe, leaving a limited phase space largely inhabited by some double degenerate systems, as well as exotic single degenerates with a sufficient time delay between mass accretion and SN explosion.

  20. SDSS-II Supernova Survey: An Analysis of the Largest Sample of Type Ia Supernovae and Correlations with Host-galaxy Spectral Properties

    NASA Astrophysics Data System (ADS)

    Wolf, Rachel C.; D'Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Fischer, John A.; Kessler, Rick; Jha, Saurabh W.; March, Marisa C.; Scolnic, Daniel M.; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C.; Olmstead, Matthew D.; Richmond, Michael; Schneider, Donald P.; Smith, Mathew

    2016-04-01

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HRs). Our sample consists of 345 photometrically classified or spectroscopically confirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric host-galaxy properties from the SDSS-SNS data release such as host stellar mass and star formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6σ significance of a nonzero linear slope. We also recover correlations between HR and host-galaxy gas-phase metallicity and specific star formation rate as they are reported in the literature. With our large data set, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically confirmed and photometrically classified SNe Ia and comment on the significance of similar combined data sets for future surveys.

  1. ASASSN-16hd Is a Type Ia SN About 16 Days Past Maximum

    NASA Astrophysics Data System (ADS)

    Bersier, D.

    2016-07-01

    We obtained a spectrum of the candidate supernova ASASSN-15hd (ATel #9227) with the SPRAT spectrograph mounted on the robotic 2m Liverpool Telescope at the Roque de los Muchachos observatory (La Palma).

  2. Host galaxy spectra and consequences for supernova typing from the SDSS SN survey

    SciTech Connect

    Olmstead, Matthew D.; Brown, Peter J.; Brownstein, Joel R.; Dawson, Kyle S.; Sako, Masao; Gupta, Ravi R.; Bassett, Bruce; Kunz, Martin; Bizyaev, Dmitry; Brinkmann, J.; Brewington, Howard; Ebelke, Garrett L.; Campbell, Heather; D'Andrea, Chris B.; Lampeitl, Hubert; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W.; and others

    2014-04-01

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey, this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of SN host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future analysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased toward lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  3. TYPE Ia SUPERNOVAE AS SITES OF THE p-PROCESS: TWO-DIMENSIONAL MODELS COUPLED TO NUCLEOSYNTHESIS

    SciTech Connect

    Travaglio, C.; Gallino, R.; Roepke, F. K.; Hillebrandt, W. E-mail: claudia.travaglio@b2fh.org

    2011-10-01

    Beyond Fe, there is a class of 35 proton-rich nuclides, between {sup 74}Se and {sup 196}Hg, called p-nuclei. They are bypassed by the s and r neutron capture processes and are typically 10-1000 times less abundant than the s- and/or r-isotopes in the solar system. The bulk of p-isotopes is created in the 'gamma processes' by sequences of photodisintegrations and beta decays in explosive conditions in both core collapse supernovae (SNe II) and in Type Ia supernovae (SNe Ia). SNe II contribute to the production of p-nuclei through explosive neon and oxygen burning. However, the major problem in SN II ejecta is a general underproduction of the light p-nuclei for A < 120. We explore SNe Ia as p-process sites in the framework of a two-dimensional SN Ia delayed detonation model as well as pure deflagration models. The white dwarf precursor is assumed to have reached the Chandrasekhar mass in a binary system by mass accretion from a giant/main-sequence companion. We use enhanced s-seed distributions, with seeds directly obtained from a sequence of thermal pulse instabilities both in the asymptotic giant branch phase and in the accreted material. We apply the tracer-particle method to reconstruct the nucleosynthesis by the thermal histories of Lagrangian particles, passively advected in the hydrodynamic calculations. For each particle, we follow the explosive nucleosynthesis with a detailed nuclear reaction network for all isotopes up to {sup 209}Bi. We select tracers within the typical temperature range for p-process production, (1.5-3.7) x 10{sup 9} K, and analyze in detail their behavior, exploring the influence of different s-process distributions on the p-process nucleosynthesis. In addition, we discuss the sensitivity of p-process production to parameters of the explosion mechanism, taking into account the consequences on Fe and alpha elements. We find that SNe Ia can produce a large amount of p-nuclei, both the light p-nuclei below A = 120 and the heavy-p nuclei, at

  4. ROTSE3 J133033.0-313427 is a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Quimby, R. M.

    2010-03-01

    A spectrum (340-760 nm) of ROTSE3 J133033.0-313427 (Zheng et al., ATel #2468) obtained on Mar 14.58 UT with the 10-m Keck I (+ Low Resolution Imaging Spectrometer) shows it to be a normal Type Ia supernova. The spectra are similar to SN 1992A a few days after maximum light (Kirshner et al. 1993, ApJ 415,589). Adopting the redshift of the apparent host (z=0.048; Katgert et al. 1998, A&AS 129, 399), the expansion velocity derived from the minimum of the SiII (rest 635.5 nm) line is about 12,000 km/s.

  5. Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Wang, Xiaofeng; Wang, Lifan; Filippenko, Alexei; Baron, Eddie; Kromer, Markus; Jack, Dennis; Zhang, Tianmeng; Aldering, Greg; Antilogus, Pierre; Arnett, W. David; Baade, Dietrich; Barris, Brian J.; Benetti, Stefano; Bouchet, Patrice; Burrows, Adam S.; Canal, Ramon; Cappellaro, Enrico; Carlberg, Raymond; di Carlo, Elisa; Challis, Peter; Crotts, Arlin; Danziger, John I.; Della Valle, Massimo; Holland, Stephen T.

    2012-01-01

    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 dataset provides unique spectral time series down to 2000 A. Significant diversity is seen in the near-maximum-light spectra (approx.2000-3500 A) 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 luminosities measured in the uvw lIF250W filter are found to correlate with the B-band light-curve shape parameter .(Delta)m15(B), but with much larger scatter relative to the correlation in the broad-band B band (e.g., approx. 0.4 mag versus approx. 0.2 mag for those with 0.8 <.(Delta)m15(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 approx. 0,9 mag and approx. 2.0 mag in the uvwl1F250W 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

  6. Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Wang, Lifan; Filippenko, Alexei V.; Baron, Eddie; Kromer, Markus; Jack, Dennis; Zhang, Tianmeng; Aldering, Greg; Antilogus, Pierre; Arnett, W. David; Baade, Dietrich; Barris, Brian J.; Benetti, Stefano; Bouchet, Patrice; Burrows, Adam S.; Canal, Ramon; Cappellaro, Enrico; Carlberg, Raymond G.; di Carlo, Elisa; Challis, Peter J.; Crotts, Arlin P. S.; Danziger, John I.; Della Valle, Massimo; Fink, Michael; Foley, Ryan J.; Fransson, Claes; Gal-Yam, Avishay; Garnavich, Peter M.; Gerardy, Chris L.; Goldhaber, Gerson; Hamuy, Mario; Hillebrandt, Wolfgang; Höflich, Peter; Holland, Stephen T.; Holz, Daniel E.; Hughes, John P.; Jeffery, David J.; Jha, Saurabh W.; Kasen, Dan; Khokhlov, Alexei M.; Kirshner, Robert P.; Knop, Robert A.; Kozma, Cecilia; Krisciunas, Kevin; Lee, Brian C.; Leibundgut, Bruno; Lentz, Eric J.; Leonard, Douglas C.; Lewin, Walter H. G.; Li, Weidong; Livio, Mario; Lundqvist, Peter; Maoz, Dan; Matheson, Thomas; Mazzali, Paolo A.; Meikle, Peter; Miknaitis, Gajus; Milne, Peter A.; Mochnacki, Stefan W.; Nomoto, Ken'ichi; Nugent, Peter E.; Oran, Elaine S.; Panagia, Nino; Perlmutter, Saul; Phillips, Mark M.; Pinto, Philip; Poznanski, Dovi; Pritchet, Christopher J.; Reinecke, Martin; Riess, Adam G.; Ruiz-Lapuente, Pilar; Scalzo, Richard A.; Schlegel, Eric M.; Schmidt, Brian P.; Siegrist, James; Soderberg, Alicia M.; Sollerman, Jesper; Sonneborn, George; Spadafora, Anthony; Spyromilio, Jason; Sramek, Richard A.; Starrfield, Sumner G.; Strolger, Louis G.; Suntzeff, Nicholas B.; Thomas, Rollin C.; Tonry, John L.; Tornambe, Amedeo; Truran, James W.; Turatto, Massimo; Turner, Michael; Van Dyk, Schuyler D.; Weiler, Kurt W.; Wheeler, J. Craig; Wood-Vasey, Michael; Woosley, Stanford E.; Yamaoka, Hitoshi

    2012-04-01

    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 Å. Significant diversity is seen in the near-maximum-light spectra (~2000-3500 Å) 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 luminosities measured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Δm 15(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., ~0.4 mag versus ~0.2 mag for those with 0.8 mag < Δm 15(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3σ), being brighter than normal SNe Ia such as SN 2005cf by ~0.9 mag and ~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.

  7. Standardization of Sn-113.

    PubMed

    Roteta, Miguel; Peyres, Virginia; García-Toraño, Eduardo

    2014-05-01

    The radionuclide (113)Sn is a quasi-monoenergetic gamma emitter often used in the efficiency calibration of gamma spectrometers in the energy region around 390keV. This paper presents the results of the standardization of this radionuclide by three methods: integral (4π-γ) counting with a well-type NaI(Tl) detector, liquid scintillation counting applying the CIEMAT-NIST method and 4π coincidence counting (conversion electron-X) with a digital coincidence system. PMID:24365465

  8. SNe Ia