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Near-IR Diagnostics for SNe

Near-IR Diagnostics for SNe. Mark M. Phillips. Carnegie Observatories. Collaborators: K. Krisciunas ( CTIO /Carnegie ), N. Suntzeff ( CTIO ) M. Hamuy ( Carnegie ), E. Persson ( Carnegie ), W. Freedman ( Carnegie ), M. Roth ( Carnegie ) L. Germany ( ESO ). Outline of Talk:

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Near-IR Diagnostics for SNe

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  1. Near-IR Diagnostics for SNe Mark M. Phillips Carnegie Observatories

  2. Collaborators: • K. Krisciunas (CTIO/Carnegie), N. Suntzeff (CTIO) • M. Hamuy (Carnegie), E. Persson (Carnegie), W. Freedman (Carnegie), M. Roth (Carnegie) • L. Germany (ESO)

  3. Outline of Talk: • SNe Ia • Morphology of NIR light curves • Light curve templates • Colors & Reddening • Absolute magnitudes & Hubble diagram • SNe II • A few words about Reddening Determinations

  4. UBVRIJHK Light Curves of a Typical SN Ia Primary maximum Secondary maximum Sources: UBVRI: Suntzeff et al. (1999) JHK: Mayya et al. (1998) Jha et al. (1999) Hernandez et al. (2000)

  5. SN m15(B) • Secondary maximum occurs laterfor slowerdeclining SNe • Generally speaking, secondary maximum is stronger for slower declining SNe

  6. Y band at 1.035 µm Secondary maximum appears to have been significantly stronger than primary maximum!

  7. Strength of Secondary Maximum vs. Decline Rate in the I Band Krisciunas et al. (2001)

  8. Krisciunas et al. (2001)

  9. Morphology of JHK lightcurves of SNe Ia: • Primary maxima occur a few days before T(Bmax) • As a general rule, the secondary maximum occurs later and is stronger in slower declining events • Secondary maximum can be brighter than primary maximum (e.g., in Y & H bands) • H & K light curves are relatively flat around T(Bmax)

  10. JHK Light Curves of 6 well-observed SNe I

  11. JHK Light Curves of the same 6 SNe I, but corrected to a stretch equivalent to m15(B) = 1.1 Let’s zoom in on this time window, and do this more precisely (e.g., include K corrections)

  12. Construction of JHK Stretch Templates SN m15(B) = 1980N (1.29) = 1986G (1.79) = 1998bu (1.05) = 1999aw (0.81) = 1999ee (0.94) = 2000ca (1.01) = 2001el (1.15)  Krisciunas et al. (2004)

  13. Fitting JHK Light Curves with the Stretch Templates m15(B) = 0.99 m15(B) = 1.73

  14. Fitting JHK Light Curves with the Stretch Templates m15(B) = 1.28 m15(B) = 1.63

  15. JHK light curve Templates for SNe Ia: • Stretch technique works well for JHK light curves in the window -12 to +10 days with respect to T(Bmax) • Allows reasonable estimates to be made of the maximum light magnitudes in JHK without the need to actually obtain photometry at maximum light • The same technique can most likely be extended to the I band as well (useful for observations of high-z SNe Ia)

  16. The B-V Color Evolution of Unreddened SNe Ia From: Phillips et al. 1999

  17. The B-V Color Evolution of Unreddened SNe Ia From: Phillips et al. 1999

  18. Colors at Maximum Light for Unreddened SNe Ia Scatter corresponds to ± 0.05 mag in E(B-V) This is as well as we can currently determine the reddening of an individual SN Ia

  19. "Realistic Case Optical" Av = (2.6±0.3) x E(B-V) "Worst Case NIR" Av = (1.126±0.072) x E(V-K) "Best Case Optical" Av = (3.1±0.1) x E(B-V) Krisciunas et al. (2000)

  20. Optical-NIR Colors of Unreddened SNe Ia SNe Ia with 0.9 < m15(B) < 1.3 Shifted to Av = 0.0 locus Krisciunas et al. (2000)

  21. Optical-NIR Colors of Unreddened SNe Ia SNe Ia with 0.8 < m15(B) < 1.0 Shifted to Av = 0.0 locus SNe Ia with 0.9 < m15(B) < 1.3 Krisciunas et al. (2004)

  22. Optical-NIR Colors vs. Δm15(B) Unreddened SNe Ia Scatter corresponds to ± 0.18 mag in Av Equivalent to ± 0.06 mag in E(B-V) This is as expected since reddening corrections were derived from BVI data Krisciunas et al. (2004)

  23. Reddening: • SNe Ia with intermediate decline rates (0.9 < m15(B) < 1.3) have similar V-IR color evolution • As expected, the V-IR color evolution of slower declining (0.8 < m15(B) < 1.0)events issomewhat bluer • Use of optical-IR color evolution to determine reddening should ultimately prove more precise than optical-only colors

  24. Absolute Magnitudes of SNe Ia Note that the luminosity vs. decline rate relaton in H may be flat Phillips et al. (2003)

  25. Are SNe Ia “Perfect” Standard Candles in the NIR? • We can try to answer this question by constructing Hubble diagrams in JHK • Available data: 7 SNe Ia observed at LCO and CTIO + 9 SNe Ia with previously published photometry • Use stretch template fits to find maximum light magnitudes • Correct for reddening based on E(B-V) values determined from BVI photometry • K corrections calculated from NIR spectra of SN 1999ee (Hamuy et al. 2002)

  26. JHK Hubble Diagrams of SNe Ia Cepheid & SBF distances used to derive “equivalent” v(cmb) assuming Ho = 72  = 0.14 mag Are the deviations from the Hubble lines a function of m15(B)?  = 0.18 mag  = 0.12 mag Krisciunas, Phillips, & Suntzeff (2004)

  27. NIR Absolute Magnitudes of SNe Ia Within the precision of the observations, there are no obvious decline rate relations in the NIR Mean values: M(J) = -18.57 ± 0.14 M(H) = -18.24 ± 0.18 M(K) = -18.42 ± 0.12 Krisciunas, Phillips, & Suntzeff (2004)

  28. Absolute Magnitudes & Hubble Diagrams: • While SNe Ia are standardizable candles in the optical bands, they apparently are standard candles in the NIR at the ± 0.20 mag level or better (± 9% in distance) • The one disadvantage of the NIR is that SNe Ia are  1 mag less luminous in JHK than they are in the V band

  29. What about SNe II in the NIR? • Plateau SNe (SNe II-P) are potentially useful distance indicators • EPM (the models need more work) • The Luminosity vs. Velocity Relation (looks encouraging) • Major source of error is determining the dust reddening • Since electron scattering is dominant opacity during plateau phase, SNe II-P should have similar similar hydrogen recombination tempertures during last part of plateau phase • As in the case of SNe Ia, Optical-NIR colors offer significant promise for improving reddening estimates of SNe II-P

  30. NIR Light Curves of a Plateau SN II SNe II-P are relatively bright in the NIR, with maximum occurring typically 2 months after explosion Hamuy et al. (2001)

  31. Comparison of B-V and V-I Color Evolution:SN 1999gi vs. SN 1999ee Color curves and reddening Av=0.50 Av=0.85 color V-I B-V time since explosion (days) Hamuy (2002)

  32. Comparison of B-V and V-I Color Evolution:SN 1999cr vs. SN 1999ee Color curves and reddening Av=-0.75 Av=0.10 color V-I B-V time since explosion (days) Hamuy (2002)

  33. Comparison of B-V and V-I Reddening Determinations (Relative to SN 1999em) Reddening Estimates • In many cases, values based on B-V are negative – differing metallicities may be responsible for this • Values based on V-I appear to be better behaved • V-NIR colors may give best estimates of all Hamuy (2002)

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