SN RATES 2008 – Arcetri, May 2008 Constraints on the DTD from SN Ia rates in Galaxies Laura Greggio INAF, Padova Astronomical Observatory

SN RATES 2008 – Arcetri, May 2008 OUTLINE Describe the DTD models in Greggio (2005) Analytic functions meant to describe the shape of the distribution expected on the basis of general arguments in stellar evolution theory. The functions have a built in parametrization of relevant astrophysical quantities. Analyze the correlations between the SNIa rates and parent galaxy colors to the end of exploring how these correlations constrain the DTD, and eventually the astrophysical parameters Conclusions

SN RATES 2008 – Arcetri, May 2008 SINGLE DEGENERATES MODELS explosion occurs when the secondary evolves off the MS

SN RATES 2008 – Arcetri, May 2008 DOUBLE DEGENERATES MODELS DD CLOSE: CE evolution causes a sizable shrinkage, distribution of GW delay skewed at short values DD WIDE: CE evolution leads to a wide distribution of DD separations

SN RATES 2008 – Arcetri, May 2008 PARAMETERS OF SD MODELS Sub-Chandra Exponents of the distributions of primary mass and mass ratio Mass limits for primary in successful systems Efficiency of accretion, important at late delay times (low secondary mass)

SN RATES 2008 – Arcetri, May 2008 PARAMETERS OF DD MODELS Mass range of the secondary Exponent for the distribution of The separations of DDs Minumum GW delay

SN RATES 2008 – Arcetri, May 2008 THE BOTTOM LINE IS: DTDs for SDs and DDs are charaterized by an early steep rise, a wide maximum, a late epoch decline Mass range of primary and secondary, their distributions, the distribution of the separations and the shrinkage during the CE phases shape the DTDs One can construct also MIXED models (SDs and DDs) in different proportions We need solid observational evidence to constrain these parameters, and derive astrophysical implications

SN RATES 2008 – Arcetri, May 2008 Correlation of the specific SNIa rate with the color of the parent galaxy Stellar Evolution naturally predicts More events at short delays THE RATE PER UNIT MASS IN LATE TYPE GALAXIES WILL BE LARGER THAN IN EARLY TYPE GALAXIES (e.g. Greggio and Renzini 1983) Bluer galaxies are ‘younger’, then they have larger specific SNIa rates

SN RATES 2008 – Arcetri, May 2008 GALAXY MODELS Families of models with some SF at current epoch, different Starting epochs, different AGE distributions within these epochs Magnitudes from population synthesis based on Girardi et al isochrones

SN RATES 2008 – Arcetri, May 2008 CORRELATION: RATE IN SNuM DDC1: DD CLOSE with M 2 >3, β=-0.9 DDW8: DD WIDE with M 2 >2, β=0 MDP: Mannucci et al. (2006) DTD GAUSSIAN: centered at 3.4 G, σ=0.7 DATA: Mannucci et al. (2005), k Ia =0.003 /Mo (adjustable) Difficult to reproduce the bluest galaxy bin : metallicity effect? The slope of the observed correlation depends on the particular Galaxy mix (AGEs and Zs) DDC1: DD CLOSE with M 2 >3, β=-0.9 DDW8: DD WIDE with M 2 >2, β=0 MDP: Mannucci et al. (2006) DTD GAUSSIAN: centered at 3.4 G, σ=0.7 DATA: Mannucci et al. (2005), k Ia =0.003 /Mo (adjustable) DDC1: DD CLOSE with M 2 >3, β=-0.9 DDW8: DD WIDE with M 2 >2, β=0 MDP: Mannucci et al. (2006) DTD GAUSSIAN: centered at 3.4 G, σ=0.7 DATA: Mannucci et al. (2005), k Ia =0.003 /Mo (adjustable)

SN RATES 2008 – Arcetri, May 2008 CORRELATION: RATE IN SNuM GALAXY MIX: young galaxies with low Z intermediate age and old galaxies with Zo DDC5: DD CLOSE M 2 >2.5 β=0 DDW4: DD WIDE M 2 >2.5 β=-0.9 SD Ch: Chandra SD flat distribution of q ε(ACC)=1 The fit improves, but …. IS IT CONSISTENT?

SN RATES 2008 – Arcetri, May 2008 Mass to Light ratio vs Color The rate in SNuM is derived by relying on Bell and De Jong (2001) models to estimate the M/L(K) ratios for various galaxies The CSP models used here have a Steeper dependence of M/L(K) on B-K for ‘young’ AGE DISTRIBUTIONS

SN RATES 2008 – Arcetri, May 2008 CORRELATION: RATE IN SNuK GALAXY MIX DDW8 (very flat) and GAUSSIAN are excluded Other DTDs are consistent END OF THE STORY?

SN RATES 2008 – Arcetri, May 2008 CORRELATION: RATE IN SNu SAME GALAXY MIX AS PREVIOUS FIGURE The rate in SNu rather indicates flat DTDs The sample of galaxies is the Same as before, but binning of galaxies is different: I’m allowed to try another galaxy mix

SN RATES 2008 – Arcetri, May 2008 CORRELATION: RATE IN SNu ANOTHER GALAXY MIX Reddest bin: exp(-t/2) Ψ(t) = K t -0.5 and Z=Zo/5 Ψ(t)=const and Z=Zo/5 ‘young’ CSPs all with Z=Zo/20 Still the rate in the bluest Galaxies is very small wrt models

SN RATES 2008 – Arcetri, May 2008 CONCLUSIONS THE FIT TO THE RELATION OF THE SPECIFIC RATE WITH PARENT GALAXY COLORS APPEARS DIFFERENT IN THE DIFFERENT BANDS NEED TO CHARACTERIZE IN DETAIL THE STELLAR POPULATIONS OF THE GALAXIES IN THE SAMPLE IN TERM OF THEIR AGE (AND METALLICITY) DISTRIBUTION TO GET RELIABLE INFO ON THE DTD ALSO THE BINNING OF THE GALAXIES TO REPRESENT THEIR AVE PROPERTIES BEARS ON THE FIT