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REDDENING

REDDENING. Nancy Elias de la Rosa. OUTLINE.  Interstellar reddening  Extinction law – Cardelli et al.  Reddening in SNIa  Photometric methods  Spectroscopic methods. Interstellar Reddening. In a galaxy only ~10 -22 of the volume is in stars.

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REDDENING

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  1. REDDENING Nancy Elias de la Rosa

  2. OUTLINE  Interstellar reddening  Extinction law – Cardelli et al.  Reddening in SNIa  Photometric methods  Spectroscopic methods

  3. Interstellar Reddening • In a galaxy only ~10-22 of the volume is in stars. • The Interstellar Medium provides 5-10% of the baryonic mass of the galaxy in form of gas mixed with tiny solid particles: dust grain. • Dust strongly affects the properties of astrophysical objects. • Dust particles interact with photons (absorbtion, scattering, polarization). This is particularly effective in optical-UV.

  4. Interstellar Reddening Dibujo del talk con los rayos azul y rojo Blue light is absorbed more than red light

  5. Interstellar Reddening

  6. Interstellar Reddening Apparent magnitude: m1() = M1() + 5 log d1 + A1() m2() = M2() + 5 log d2 + A2() where 1 = ‘reddened’ star; 2 = ‘comparison’ star if M1() = M2() => m() = 5 log (d1/d2) + A() for 1 and 2: Enorm= (m() - m(2)) / (m(1) - m(2)) = (A() - A(2)) / (A(1) - A(2)) = E( - 2) / E(1- 2) where Enorm = normalized extinction Extinction curve: E(-V) A() - A(V)  A()  A(V) = = RV - 1 => RV = E(B-V) E(B-V)  A(V)  E(B-V)

  7. Cardelli´s extinction law Extinction law = A()/A(V)  Parameterization: the average Rv-dependent Extinction Law A()/A(V) = a(x) + b(x)/Rv (x= -1)  Rv affects the shape of the extinction curves (particularly at the shorter wavelengths) Cardelli et al. 1989

  8. Cardelli´s extinction law A bump around 2175 Å Serious deviation for x > 7 m-1 Shape independent on Rv in the NIR Cardelli et al. 1989

  9. RV ratio-of-total-extinction AB = RB x E(B-V) RB = 4.14 ± 0.15 (Savage & Mathis 1979) 1.70 ± 0.33 (Capaccioli et al. 1990) 3.35 ± 0.25 (Della Valle & Panagia 1992) 3.55 ± 0.30 (Riess et al. 1996) 2.09 (Tripp 1998) 3.5 ± 0.4 (Phillips et al. 1999) 2.8 (Krisciunas et al. 2000) 3.88 ± 0.15 (Wang et al. 2003) 3.5 (Altavilla et al. 2004) 3.65 ± 0.21 (Reindl et al. 2005) 3.1 ± 0.5 (Elias et al. 2005) (here RB RV + 1)

  10. Reddening in SN Ia SN 2003cg SN 1994D

  11. Reddening in SN Ia • morphology of • the host galaxy SNe in E or S0 galaxies are less affected by dust (2) position of the SN in the host galaxy (3) absence of interstellar NaI line

  12. Na ID Turatto et al. 2003

  13. Na ID SN2003cg

  14. Lira (30  tv  90) Lira 1995 Phillips et al. 1999

  15. Phillips Relations: Bmax-Vmax (at max) Phillips et al. 1999

  16. Lira (at late time) (at max) Phillips Relation: Vmax-Imax and tail Phillips et al. 1999

  17. Reindl Relations There are also relations at +35 days Reindl et al. 2005

  18. Multicolor Light Curve Shape (MLCS) Riess et al. 1996

  19. CMAGIC Wang et al. 2003

  20. Extinction Curves Comparison (Similar m15 and spectra features) Unreddened SN Reddened SN F F0 Corrected by redshift and Galactic reddening Put at same distance A() = -2.5 log (F /F0) normalize to A(V) ratio = approximate extinction curve to be compared with the theoretical Cardelli's extinction law.

  21. Extinction Curves Comparison At maximum

  22. Extinction Curves Comparison At +30 days

  23. Spectral Comparison E(B-V) = 1.22 RV = 2.0

  24. Optical Color Evolution E(B-V) = 1.22 RV = 2.0

  25. IR Color Evolution E(B-V) = 1.22 RV = 2.0

  26. Relation between Rv and E(B-V) (R RV) Fitzpatrick 1999

  27. IR Spectra Rudy et al. 2002

  28. Diffuse Interstellar Bands Herbig 1995

  29. Diffuse Interstellar Bands 6283.86 Å

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