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Studies of Type Ia Supernovae for Precision Cosmology:

Studies of Type Ia Supernovae for Precision Cosmology: Current research activities and future plans Vallery Stanishev CENTRA – IST, Lisbon. V. Stanishev Lisbon, 17 Oct 2008.

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Studies of Type Ia Supernovae for Precision Cosmology:

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  1. Studies of Type Ia Supernovae for Precision Cosmology: Current research activitiesand future plans Vallery Stanishev CENTRA – IST, Lisbon V. Stanishev Lisbon, 17 Oct 2008

  2. Current research activities Detailed studies of nearby SNe Ia Motivated by the application of SNe Ia in cosmology, the main goal is to improve the SN Ia standard candle by understanding and achieving better control over the most important systematic uncertainties involved

  3. Supernova Ia Cosmology What is the nature of the Dark Energy? Need better SN Ia observations to measure parameters sensitive to the dark energy SNe Ia are excellent standardisible candles that led to the discovery of the accelerated expansion of the Universe and the mysterious Dark Energy Test for evolution with redshift: w=w0+wa z/(1+z) (scalar field models) w0 = -1? (cosmological constant) Need measurements better than 2%

  4. SNe Ia Cosmology: systematics • Extinction by dust in the host galaxy • - uncertainties of intrinsic SN Ia colors • - calibration of the observations • - poorly know dust properties 2. Evolution of SNe Ia properties - the progenitor systems are unknown - details of the complicated physics of the explosion are not well understood - the corrections to standardize the SNe Ia luminosity is purely empirical and not understood theoretically - sensitivity of the SN Ia luminosity to the parameters of the WD (metalicity, C/O ratio, …) 3. Contamination of other SN types - the observations of high-z SNe are rather noisy

  5. Nearby bright SNe Ia Asiago 1.82m Russia TNG, NOT WHT, INT Calar Alto 3.5m & 2.2m UKIRT NTT, 2.2m VLT Funded 2002-2006 SSO • GOALS • to obtain well-sampled high-quality observations • of bright SNe Ia • 2. study their properties in detail in order to improve • the SN Ia standard candle through: • Achieving better understanding the intrinsic SNe Ia colors and • the dust extinction corrections • - gaining more insights into the physics of the explosion by modeling • the spectra and the light curves • - Feedback into the models and improve them

  6. Nearby bright SNe Ia One person takes the lead to coordinate the observations of given SN, performs reduction and analysis of the data SN 2002bo, 2002hv, 2002er, 2002dj, 2003cg,2003du,2003gs, 2003kf,2004S, 2004aw, 2004dt, 2004eo, 2005W, 2005bl, 2005cf, 2005hk,2006X, 2006jc,2007gi, 2007gr, 2008Q, 2008S Target-of-Opportunity observations at the Nordic Optical Telescope since 2003

  7. Nearby bright SNe Ia One person takes the lead to coordinate the observations of given SN, perform reduction and analysis of the data SN 2002bo, 2002hv, 2002er, 2002dj, 2003cg,2003du,2003gs, 2003kf,2004S, 2004aw, 2004dt, 2004eo, 2005W, 2005bl, 2005cf, 2005hk,2006X, 2006jc,2007gi, 2007gr, 2008Q, 2008S Target-of-Opportunity observations at the Nordic Optical Telescope since 2003

  8. Results: SN 2003du Stanishev et al., A&A, 2007

  9. Results: SN 2003du • Properties of SN 2003du • Normal SN Ia with ΔM15 = 1.02 mag • Spectroscopically normal • 3. No reddening in the host galaxy • (Study the intrinsic colors) • 4. ~0.7 M⊙ of 56Ni was synthesized • A typical Type Ia supernova • that fits well the general picture. • Good for cosmology

  10. The case of SN 2005hk: peculiar SN Ia Stanishev et al., (in prep.) 3. Lack of secondary maximum in I & R 4. 10 days delay between B & I max 1. ΔM15 = 1.6 mag 2. Underluminous by ~1.6 mag

  11. The case of SN 2005hk: peculiar SN Ia Stanishev et al., A&A, 2008, (in prep.)

  12. The case of SN 2005hk: peculiar SN Ia • Slowly expanding ejecta • Hot spectra (doubly ionized species) • Very effective mixing • Completely different late time spectra

  13. Results SN 2005cf Published: 2003du - Stanishev et al. 2007 2004S - Krisciunas et al. 2007 2004aw - Taubenberger et al. 2007 2004dt - Altavilla et al. 2007 2004eo - Pastorello et al. 2007 2005cf - Pastorello et al. 2007; Garavini et al. 2007 2006jc - Pastorello et al. 2007 2007gr - Valenti et al. 200 In preparation: 2005hk - Stanishev et al. 2006X - Rosa et al. 2003gs - Stanishev et al. 2003kf - ? 2008S - Botichella et al. 2007gi - Stanishev et al. 2008Q - Stanishev et al.

  14. Results: high-velocity features HV Ca II ~20000 km/s Very often observed in the early spectra Mazzali,…, Stanishev, et al. ApJ, 2005

  15. Additional research topics • Deep near infrared imaging of massive galaxy clusters • to search for gravitationally lensed very distant SNe • (organizing and leading the VLT observations; data • reduction and photometric analysis) • Series of paper out soon • 2. NIR observations of intermediate redshift SNe Ia. • I organized and led the observations at VLT • Nordic Optical Telescope and South Africa. • 3. Studies of binary stars • 4. Cosmology with intermediate and high-redshift SNe Ia • with SCP and yet another European effort in 1999 • 5. Studies of core-collapse SNe (with ESC)

  16. Future work Main focus on systematic uncertainties in SN Ia cosmology 1. Detailed studies of nearby bright SNe 2. Studies of SNe Ia host galaxies 3. NIR photometry of intermediate redshift SNe Ia 4. Statistical studies of SN Ia spectra and light-curves 5. Organize a small workshop on dust in SN Ia environments. 6. Work closely with students and involve them in the research

  17. the interstellar Na I absorption lines (5890.0, 5895.9Å) are sensitive probe of the dust extinction 1. Uniform V-NIR Color indices 2. NIR is much less sensitive to dust extinction. V-NIR can be used to measure the extinction Na I High-resolution spectroscopy Detailed studies of nearby bright SNe Ia Observations that I have collected / will collect through my observing program at NOT and other facilities, and though collaborations 1. elucidation the origin of the intrinsic color dispersion of SNe Ia and improving the accuracy of the methods to estimate the dimming by dust in the host galaxy Combined analysis of optical and NIR data proviced 3 times more accurate extinction estimaiton Krisciunas, Garnavich, Stanishev et al. 2007 (SN 2004S) 2. detailed analysis of collected observations with state-of-the-art spectral and light curves modeling codes in order to gain more insights into the physics of SNe Ia and their progenitors - abundance tomography to analyze spectra and light-curves

  18. SNe Ia models: spectra formation Thermonuclear explosion of massive WD leaves an expanding onion-like layered chemical ejecta C/O Si/S/Ca 56Ni Fe

  19. Tanaka, Mazzali, Stanishev et al. in prep. Abundance Tomography of SN 2003du Carefully model early-time spectral time series in order to recover the composition layering of the ejecta SN 2003du Stanishev et al. 2007

  20. Abundance Tomography • 1. Mixing in the ejecta • not predicted in the models • helps to fit better the • bolometric light curves • Indications for turbulent • burning front propagation? • 2. Little C in the outer • ejecta • indicates Deflagration • to Detonation transition

  21. Detailed studies of nearby bright SNe Ia Observations that I have collected / will collect through my observing program at NOT and other facilities, and though collaborations 1. elucidation the origin of the intrinsic color dispersion of SNe Ia and improving the accuracy of the methods to estimate the dimming by dust in the host galaxy 2. detailed analysis of collected observations with state-of-the-art spectral and light curves modeling codes in order to gain more insights into the physics of SNe Ia and their progenitors - abundance tomography to analyze spectra and light-curves 3. Such observations are already obtained for SNe 2007gi and 2008Q. The observing program is ongoing and more data will be collected The studies of peculiar SNe Ia and SNe Ic will be conducted with the same methodology

  22. NIR photometry of intermediate redshift SNe Ia Light curves described well by single templates No dependence of NIR peak magnitudes on ΔM15 4-10 times less sensitive to dust extinction Even better standard candles than in the optical? Combined optical-NIR observations have the potential to be a powerful nearly systematics-free probe of dark energy for the next generation space SN Ia projects We have already obtained and plan to obtain more optical+NIR observations of SNe at z=0.05-0.18. This will extend the NIR SN Ia Hubble Diagram from current z=0.03 to z=0.18.

  23. Studies of SNe Ia host galaxies • Use medium-resolution spectroscopy to characterize • the global properties of galaxies that hosted SNe Ia, • e.g. metal abundances, electronic density, extinction, • and stellar populations • 2. Correlate them with the properties of SNe Ia in order to • quantify the effect of the supernova environment on • the intrinsic SNe Ia luminosities. • 3. Put constrains on the progenitors of SNe Ia. Involve students in the observations!!!

  24. Statistical studies of SN Ia • Wavelet analysis of SNe spectra, both for accurate • classification of noisy high-reshift SNe spectra and • quantitative statistical analysis. • - excellent de-noising tool • - explore the wealth of information coded in the • wavelet coefficients, .e.g on absorption line profiles • and other intrinsic differences between the spectra • 2. Statistical analysis of SNe Ia light curves • - color-color diagrams

  25. Workshop on dust in SN Ia • Bring together expertise from both SN and interstellar • dust communities to tackle this important issue • 2. Properties of cirrcumstellar dust in SNe Ia. • - How dust is created, destroyed or modified under • the intense SN radiation. • - Why dust properties of distant SNe are different • than MW dust. • - It this a dust effect or unknown property of SNe Ia colors? • 3. The importance of scattering from inhomogeneous • cirrcumstellar dust clouds • - effective extinction law

  26. Expected results Improve the SN Ia standard candle • Development of more accurate photometric methods • for estimation of dust extinction to the high redshift SNe Ia • 2. Advances in our understanding of the physics of the • SNe Ia thermonuclear explosions • 3. Better understanding the infrared properties of SNe Ia and • test the viability of NIR as standard candle • 4. Help to find the elusive SN Ia progenitors • 5. Understand the intrinsic spectral difference among SNe Ia • 6. Strengthen and expand the research activities of CENTRA • of this most outstanding field of Astrophysics

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