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Title: PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806

Abstract

Context. In this paper, we investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by the (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from the host-galaxy center. We classify PTF12os as a Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified as Type Ib having a likely progenitor with zero age main sequence (ZAMS) mass below ~17 M . Because of the shared and nearby host, we are presented with a unique opportunity to compare these two SNe. Aims. Our main objective is to constrain the explosion parameters of iPTF12os and iPTF13bvn, and to put constraints on the SN progenitors. We also aim to spatially map the metallicity in the host galaxy, and to investigate the presence of hydrogen in early-time spectra of both SNe. Methods. We present comprehensive datasets collected on PTF12os and iPTF13bvn, and introduce a new automatic reference-subtraction photometry pipeline (FPipe) currently in use by the iPTF. We perform a detailed study of the light curves (LCs) and spectral evolution of the SNe. The bolometric LCs are modeled using the hydrodynamical code hyde. Wemore » analyze early spectra of both SNe to investigate the presence of hydrogen; for iPTF13bvn we also investigate the regions of the Paschen lines in infrared spectra. We perform spectral line analysis of helium and iron lines to map the ejecta structure of both SNe. We use nebular models and late-time spectroscopy to constrain the ZAMS mass of the progenitors. We also perform image registration of ground-based images of PTF12os to archival HST images of NGC 5806 to identify a potential progenitor candidate. Results. We find that our nebular spectroscopy of iPTF13bvn remains consistent with a low-mass progenitor, likely having a ZAMS mass of ~12M . Our late-time spectroscopy of PTF12os is consistent with a ZAMS mass of ~15M . We successfully identify a source in pre-explosion HST images coincident with PTF12os. The colors and absolute magnitude of this object are consistent between pre-explosion and late-time HST images, implying it is a cluster of massive stars. Our hydrodynamical modeling suggests that the progenitor of PTF12os had a compact He core with a mass of 3.25 + 0.77 -0.56M at the time of the explosion, which had a total kinetic energy of 0.54 + 0.41 -0.25 × 10 51 erg and synthesized 0.063 + 0.020 -0.011M of strongly mixed 56Ni. Spectral comparisons to the Type IIb SN 2011dh indicate that the progenitor of PTF12os was surrounded by a thin hydrogen envelope with a mass lower than 0.02M . We also find tentative evidence that the progenitor of iPTF13bvn could have been surrounded by a small amount of hydrogen prior to the explosion. Finally, this result is supported by possible weak signals of hydrogen in both optical and infrared spectra.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [1];  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [4];  [12];  [13];  [14];  [1] more »;  [15];  [4] « less
  1. Stockholm Univ. (Sweden)
  2. Univ. of Cambridge (United Kingdom)
  3. Las Cumbres Observatory Global Telescope Network, Goleta, CA (United States)
  4. Queen's Univ., Belfast, Northern Ireland (United Kingdom)
  5. Las Cumbres Observatory Global Telescope Network, Goleta, CA (United States); Weizmann Inst. of Science, Rehovot (Israel)
  6. INAF-Astrophysical Observatory of Catania (Italy)
  7. INAF-Astronomical Observatory of Padua (Italy)
  8. Univ. of California, Berkeley, CA (United States)
  9. Pennsylvania State Univ., University Park, PA (United States)
  10. Weizmann Inst. of Science, Rehovot (Israel)
  11. Las Cumbres Observatory Global Telescope Network, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States)
  12. Liverpool John Moores Univ., Liverpool (United Kingdom); Max Planck Inst. for Astrophysics, Garching (Germany)
  13. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  14. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  15. INAF Inst. of Space Astrophysics and Cosmic Physics, Bologna (Italy); Scuola Normale Superiore di Pisa (Italy)
Publication Date:
Research Org.:
Stockholm Univ. (Sweden); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Swedish Research Council (SRC); European Research Council (ERC)
OSTI Identifier:
1393073
Grant/Contract Number:
AC02-05CH11231; 291222
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 593; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; supernovae; PTF12os; NGC 5806; galaxies; image processing; iPTF13bvn

Citation Formats

Fremling, C., Sollerman, J., Taddia, F., Ergon, M., Fraser, M., Karamehmetoglu, E., Valenti, S., Jerkstrand, A., Arcavi, I., Bufano, F., Elias Rosa, N., Filippenko, A. V., Fox, D., Gal-Yam, A., Howell, D. A., Kotak, R., Mazzali, P., Milisavljevic, D., Nugent, P. E., Nyholm, A., Pian, E., and Smartt, S.. PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806. United States: N. p., 2016. Web. doi:10.1051/0004-6361/201628275.
Fremling, C., Sollerman, J., Taddia, F., Ergon, M., Fraser, M., Karamehmetoglu, E., Valenti, S., Jerkstrand, A., Arcavi, I., Bufano, F., Elias Rosa, N., Filippenko, A. V., Fox, D., Gal-Yam, A., Howell, D. A., Kotak, R., Mazzali, P., Milisavljevic, D., Nugent, P. E., Nyholm, A., Pian, E., & Smartt, S.. PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806. United States. doi:10.1051/0004-6361/201628275.
Fremling, C., Sollerman, J., Taddia, F., Ergon, M., Fraser, M., Karamehmetoglu, E., Valenti, S., Jerkstrand, A., Arcavi, I., Bufano, F., Elias Rosa, N., Filippenko, A. V., Fox, D., Gal-Yam, A., Howell, D. A., Kotak, R., Mazzali, P., Milisavljevic, D., Nugent, P. E., Nyholm, A., Pian, E., and Smartt, S.. 2016. "PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806". United States. doi:10.1051/0004-6361/201628275. https://www.osti.gov/servlets/purl/1393073.
@article{osti_1393073,
title = {PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806},
author = {Fremling, C. and Sollerman, J. and Taddia, F. and Ergon, M. and Fraser, M. and Karamehmetoglu, E. and Valenti, S. and Jerkstrand, A. and Arcavi, I. and Bufano, F. and Elias Rosa, N. and Filippenko, A. V. and Fox, D. and Gal-Yam, A. and Howell, D. A. and Kotak, R. and Mazzali, P. and Milisavljevic, D. and Nugent, P. E. and Nyholm, A. and Pian, E. and Smartt, S.},
abstractNote = {Context. In this paper, we investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by the (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from the host-galaxy center. We classify PTF12os as a Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified as Type Ib having a likely progenitor with zero age main sequence (ZAMS) mass below ~17 M⊙. Because of the shared and nearby host, we are presented with a unique opportunity to compare these two SNe. Aims. Our main objective is to constrain the explosion parameters of iPTF12os and iPTF13bvn, and to put constraints on the SN progenitors. We also aim to spatially map the metallicity in the host galaxy, and to investigate the presence of hydrogen in early-time spectra of both SNe. Methods. We present comprehensive datasets collected on PTF12os and iPTF13bvn, and introduce a new automatic reference-subtraction photometry pipeline (FPipe) currently in use by the iPTF. We perform a detailed study of the light curves (LCs) and spectral evolution of the SNe. The bolometric LCs are modeled using the hydrodynamical code hyde. We analyze early spectra of both SNe to investigate the presence of hydrogen; for iPTF13bvn we also investigate the regions of the Paschen lines in infrared spectra. We perform spectral line analysis of helium and iron lines to map the ejecta structure of both SNe. We use nebular models and late-time spectroscopy to constrain the ZAMS mass of the progenitors. We also perform image registration of ground-based images of PTF12os to archival HST images of NGC 5806 to identify a potential progenitor candidate. Results. We find that our nebular spectroscopy of iPTF13bvn remains consistent with a low-mass progenitor, likely having a ZAMS mass of ~12M⊙. Our late-time spectroscopy of PTF12os is consistent with a ZAMS mass of ~15M⊙. We successfully identify a source in pre-explosion HST images coincident with PTF12os. The colors and absolute magnitude of this object are consistent between pre-explosion and late-time HST images, implying it is a cluster of massive stars. Our hydrodynamical modeling suggests that the progenitor of PTF12os had a compact He core with a mass of 3.25+ 0.77-0.56M⊙ at the time of the explosion, which had a total kinetic energy of 0.54+ 0.41-0.25 × 1051 erg and synthesized 0.063+ 0.020-0.011M⊙ of strongly mixed 56Ni. Spectral comparisons to the Type IIb SN 2011dh indicate that the progenitor of PTF12os was surrounded by a thin hydrogen envelope with a mass lower than 0.02M⊙. We also find tentative evidence that the progenitor of iPTF13bvn could have been surrounded by a small amount of hydrogen prior to the explosion. Finally, this result is supported by possible weak signals of hydrogen in both optical and infrared spectra.},
doi = {10.1051/0004-6361/201628275},
journal = {Astronomy and Astrophysics},
number = ,
volume = 593,
place = {United States},
year = 2016,
month = 9
}

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  • We study properties of early radio emission from stripped-envelope supernovae (SNe; those of Type IIb/Ib/Ic). We suggest there is a sub-class of stripped-envelope SNe based on their radio properties, including the optically well-studied Type Ic SNe (SNe Ic) 2002ap and 2007gr, showing a rapid rise to a radio peak within {approx}10 days and reaching a low luminosity (at least an order of magnitude fainter than a majority of SNe IIb/Ib/Ic). They show a decline after the peak that is shallower than that of other stripped-envelope SNe while their spectral index is similar. We show that all these properties are naturallymore » explained if the circumstellar material (CSM) density is low and therefore the forward shock is expanding into the CSM without deceleration. Since the forward shock velocity in this situation, as estimated from the radio properties, still records the maximum velocity of the SN ejecta following the shock breakout, observing these SNe in radio wavelengths provides new diagnostics on the nature of both the breakout and the progenitor which otherwise require a quite rapid follow-up in other wavelengths. The inferred post-shock breakout velocities of SNe Ic 2002ap and 2007gr are sub-relativistic, {approx}0.3c. These are higher than that inferred for SN II 1987A, in line with suggested compact progenitors. However, these are lower than expected for a Wolf-Rayet (W-R) progenitor. It may reflect an as yet unresolved nature of the progenitors just before the explosion, and we suggest that the W-R progenitor envelopes might have been inflated which could quickly reduce the maximum ejecta velocity from the initial shock breakout velocity.« less
  • The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence in the optical and infrared suggests a Type Ib classification. We identify a blue progenitor candidate in deep pre-explosion imaging within a 2σ error circle of 80 mas (8.7 pc). The candidate has an M{sub B} luminosity of –5.52 ± 0.39 mag and a B – I color of 0.25 ± 0.25 mag. If confirmed by future observations, this would be the first direct detection for a progenitor of a Type Ib. Fitting a power lawmore » to the early light curve, we find an extrapolated explosion date around 0.6 days before our first detection. We see no evidence of shock cooling. The pre-explosion detection limits constrain the radius of the progenitor to be smaller than a few solar radii. iPTF13bvn is also detected in centimeter and millimeter wavelengths. Fitting a synchrotron self-absorption model to our radio data, we find a mass-loading parameter of 1.3×10{sup 12} g cm{sup –1}. Assuming a wind velocity of 10{sup 3} km s{sup –1}, we derive a progenitor mass-loss rate of 3 × 10{sup –5} M {sub ☉} yr{sup –1}. Our observations, taken as a whole, are consistent with a Wolf-Rayet progenitor of the supernova iPTF13bvn.« less
  • The optical and optical/near-infrared pseudo-bolometric light curves of 85 stripped-envelope supernovae (SNe) are constructed using a consistent method and a standard cosmology. The light curves are analysed to derive temporal characteristics and peak luminosity L p , enabling the construction of a luminosity function. Subsequently, the mass of 56 Ni synthesized in the explosion, along with the ratio of ejecta mass to ejecta kinetic energy, are found. Analysis shows that host-galaxy extinction is an important factor in accurately determining luminosity values as it is significantly greater than Galactic extinction in most cases. It is found that broad-lined SNe Ic (SNemore » Ic-BL) and gamma-ray burst SNe are the most luminous subtypes with a combined median L p , in erg s -1 , of log(L p) = 43.00 compared to 42.51 for SNe Ic, 42.50 for SNe Ib, and 42.36 for SNe IIb. It is also found that SNe Ic-BL synthesize approximately twice the amount of 56Ni compared with SNe Ic, Ib, and IIb, with median M Ni = 0.34, 0.16, 0.14, and 0.11 M ⊙ , respectively. SNe Ic-BL, and to a lesser extent SNe Ic, typically rise from L p /2 to L p more quickly than SNe Ib/IIb; consequently, their light curves are not as broad.« less
  • We present optical spectra of SN 2007gr, SN 2007rz, SN 2007uy, SN 2008ax, and SN 2008bo obtained in the nebular phase when line profiles can lead to information about the velocity distribution of the exploded cores. We compare these to 13 other published spectra of stripped-envelope core-collapse supernovae (Type IIb, Ib, and Ic) to investigate properties of their double-peaked [O I] lambdalambda6300, 6364 emission. These 18 supernovae are divided into two empirical line profile types: (1) profiles showing two conspicuous emission peaks nearly symmetrically centered on either side of 6300 A and spaced approx64 A apart, close to the wavelengthmore » separation between the [O I] lambdalambda6300, 6364 doublet lines, and (2) profiles showing asymmetric [O I] line profiles consisting of a pronounced emission peak near 6300 A plus one or more blueshifted emission peaks. Examination of these emission profiles, as well as comparison with profiles in the lines of [O I] lambda5577, O I lambda7774, and Mg I] lambda4571, leads us to conclude that neither type of [O I] double-peaked profile is necessarily the signature of emission from front and rear faces of ejecta arranged in a toroidal disk or elongated shell geometry as previously suggested. We propose possible alternative interpretations of double-peaked emission for each profile type, test their feasibility with simple line-fitting models, and discuss their strengths and weaknesses. The underlying cause of the observed predominance of blueshifted emission peaks is unclear, but may be due to internal scattering or dust obscuration of emission from far side ejecta.« less
  • We study the multi-dimensional geometry of supernova (SN) explosions by means of spectropolarimetric observations of stripped-envelope SNe, i.e., SNe without a hydrogen-rich layer. We perform spectropolarimetric observations of two stripped-envelope SNe, Type Ib SN 2009jf and Type Ic SN 2009mi. Both objects show non-zero polarization at the wavelength of the strong lines. They also show a loop in the Stokes Q - U diagram, which indicates a non-axisymmetric, three-dimensional ion distribution in the ejecta. We show that five out of six stripped-envelope SNe, which have been observed spectropolarimetrically so far, show such a loop. This implies that a three-dimensional geometrymore » is common in stripped-envelope SNe. We find that stronger lines tend to show higher polarization. This effect is not related to the geometry, and must be corrected for to compare the polarization of different lines or different objects. Even after the correction, however, there remains a dispersion of polarization degree among different objects. Such a dispersion might be caused by three-dimensional clumpy ion distributions viewed from different directions.« less