1 / 15

Keiichi Maeda (@MPA → IPMU) MPA: Max-Planck-Institute for Astrophysics

Supernovae are NOT spherical: The result from late-time spectroscopy by FOCAS “Asphericity in Supernova Explosions from Late-Time Spectroscopy”, Keiichi Maeda et al., Science, 31 January issue (online version). Keiichi Maeda (@MPA → IPMU) MPA: Max-Planck-Institute for Astrophysics

davin
Download Presentation

Keiichi Maeda (@MPA → IPMU) MPA: Max-Planck-Institute for Astrophysics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Supernovae are NOT spherical: The result from late-time spectroscopy by FOCAS“Asphericity in Supernova Explosions from Late-Time Spectroscopy”, Keiichi Maeda et al., Science, 31 January issue (online version) Keiichi Maeda (@MPA → IPMU) MPA: Max-Planck-Institute for Astrophysics IPMU: Institute for the Physics and Mathematics of the Universe 「Subaru UM」 ＠NAOJ, 30 Jan 2008 1/15

  2. Collaborators • S. Taubenberger (MPA) • M. Iye (NAOJ) • T. Matheson (Tucson) • A.V. Filippenko (UC Berkeley) • K. Aoki (Subaru) • G. Kosugi (NAOJ) • Y. Ohyama (JAXA) • T. Sasaki (Subaru) • T. Takata (NAOJ) • K. Maeda (MPA/IPMU) • K. Kawabata (Hiroshima) • P.A. Mazzali (MPA/Trieste) • M. Tanaka (Tokyo) • S. Valenti (ESO) • K. Nomoto (Tokyo/IPMU) • T. Hattori (Subaru) • J. Deng (NAOC) • E. Pian (Trieste) 「Subaru UM」 ＠NAOJ, 30 Jan 2008 2/15

  3. Core-Collapse Supernovae (CC-SNe) • The end product of a massive star（M > 8 M8） • Core-collapse  Explosion（E ~ 1051 erg） • Origin of heavy elements. • My talk is especially on “stripped” CC-SNe. • A subclass, a progenitor has lost its H envelope before the explosion. (23rd Feb. 1987) SN 1987A (not stripped) 「Subaru UM」 ＠NAOJ, 30 Jan 2008

  4. Questions • The explosion mechanism(s) of Core-Collapse Supernovae (CC-SNe)? “Easier” questions • The explosion geometry of CC-SNe? 「Subaru UM」 ＠NAOJ, 30 Jan 2008 4/15

  5. Why geometry? • Theoretical scenarios • SASI, rotation, MHD, Collapser…(and so forth) Blondin+ 2003 Kotake+ 2004 MacFadyen & Woosley 1999 (Some) Proposed scenarios predict bipolar explosions. The geometry is closely related to the explosion mechanism. 「Subaru UM」 ＠NAOJ, 30 Jan 2008 5/15

  6. OK. Geometry seems important. But HOW CAN YOU LOOK INTO THAT? • An SN is observed as a point source. • Only very few exceptions (e.g., 87A) • Late-time spectroscopy (~ 1 year after the explosion)! • Optically thin (expansion) + simple velocity law (v ∝ r). blueshift redshift wavelength 「Subaru UM」 ＠NAOJ, 30 Jan 2008 6/15

  7. Spherical models • ANY spherical distribution should produce “SINGLE-PEAKED” [OI] 6300&6363. • 6363A component negligible at late-phase. • Negligible transfer effect to distort the line profile. • Irrespective the radial density distribution, you always have the maximum cross section at the supernova center. • The line should peak at the rest wavelength. 「Subaru UM」 ＠NAOJ, 30 Jan 2008 7/15

  8. Subaru/FOCAS Observation Previous • Spectroscopy@200day. • Faint (R ~ 20 – 24 mag). • Often fainter than a background diffuse HII region. • ~ 0.5 – 4 hr by 8m! • Subaru/FOCAS (+ VLT)! • KM, KK, MT + TH, KA. • After subtracting possible biases (later), 15 SNe. • Previously, only 3 SNe. • 18 SNe = 6 times the previous sample!!! This work 「Subaru UM」 ＠NAOJ, 30 Jan 2008 8/15

  9. Observational Result • Discovery of the double-peaked [OI] in at least 5 SNe (at most 9) out of 18. • The double-peak is NOT an unusual features! • Asphericity is a common feature in SNe!! 「Subaru UM」 ＠NAOJ, 30 Jan 2008 9/15

  10. Fe (56Ni) O At observations （＞1day） To be more quantitative: Aspherical models BP16 8 4 2 1 ρ 56Ni(Fe) Ca O Maeda+ 02, ApJ, 565, 405 Oxygen distributed in a disk. Spherical A sequence of phenomenological (parameterized) models. Params.: BP (Asphericity), θ 「Subaru UM」 ＠NAOJ, 30 Jan 2008 10/15

  11. Statistics of the [OI] profile! Singly Peaked Maeda+ 06, ApJ, 640, 854 Expected frequency 36% Extreme Model BP8 0 deg 30 deg Doubly Peaked < 30o Z：0 deg 60 deg Expected frequency 64% 90 deg R：90 deg O 「Subaru UM」 ＠NAOJ, 30 Jan 2008 11/15

  12. BP16 8 4 2 1 ρ 56Ni(Fe) Ca O Spherical Statistics of the [OI] profile BP8 vs BP2 • BP8 = 64% double-peaked, BP2 = 34%, BP1 = 0%. double vs. single 「Subaru UM」 ＠NAOJ, 30 Jan 2008 12/15

  13. Asphericity is a common feature, but HOW? • Double peaked fraction = 28 – 50% (median 39%). • Uncertainty comes from “transitional” profiles. vs. • BP8 predicts 64%, BP2 = 34%, and BP1 = 0%. • Most, if not all, CC-SNe are NOT spherical. • On average, CC-SNe are moderately aspherical. 「Subaru UM」 ＠NAOJ, 30 Jan 2008 13/15

  14. Interpretation: Geometry of CC-SNe Average geometry of CC-SNe, Moderately aspherical. First observational support of recently proposed explosion scenarios. 「Subaru UM」 ＠NAOJ, 30 Jan 2008 14/15

  15. Conclusions & Implication • Core-collapse SNe do have asphericity. • Mildly(?) aspherical (consistent with model BP2). • Not discussed in this talk, but important implication. • The average asphericity looks smaller than special, energetic SNe (Hypernovae). • Previous study indicates a geometry similar to BP8 for a very ebergetic SN 1998bw (associated with a Gamma-ray burst). Maeda+ 06, ApJ, 640, 854; Maeda 06, ApJ, 644, 385; Maeda+ 06, ApJ, 645, 1331; Tanaka+ 07, 668, L19 「Subaru UM」 ＠NAOJ, 30 Jan 2008 15/15

More Related