Progenitor Constraints from SNe Ia Observations at Late Times Melissa L. Graham, UC Berkeley Wednesday August 5 Carnegie SNIa Progenitors Workshop Today’s topics will include... 1. Nebular twins SNe Ia 2011fe and 2011by. 2. The ~1000 day spectrum of normal SN Ia 2011fe. 3. Intracluster supernovae. 4. Discussion questions.
Twin Type Ia Supernovae Previous works with twin Type Ia supernovae include: Silverman et al. (2013) “SN 2000cx and SN 2013bh: extremely rare, nearly twin Type Ia supernovae” - peculiar SNe Ia (high temperature, high velocity features, large 56 Ni masses) Fakhouri Ph.D. Thesis 2013 “Supernova Ia Spectra and Spectrophotometric Time Series: Recognizing Twins and the Consequences for Cosmological Distance Measurements” - considers normal SNe Ia (i.e., for cosmological analyses) - even the closest spectroscopic twins have ∆ m~0.1 mag (their Fig 3.7) Foley & Kirshner (2013) “Metallicity Differences in Type Ia Supernova Progenitors Inferred from Ultraviolet Spectra” - progenitor metallicity affects NUV flux in normal, optically twin SNe Ia
Twin Type Ia Supernovae Foley & Kirshner (2013) “Metallicity Differences in Type Ia Supernova Progenitors Inferred from Ultraviolet Spectra” Spectra - optically twins - NUV flux discrepancy Light Curves - decline rate twins - discrepant peak brightness M B,peak M 56Ni Z 11fe -19.07 ~0.53 M ~1 Z ☉ ☉ 11by -18.47 ~0.31 M ~4 Z ☉ ☉ Model spectra with varying abundances from Lentz+ 2000.
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by” Spectra - optically twins - NUV flux discrepancy Identical evolution in the silicon velocity over time.
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by” Absolute magnitude light curves using Residual light curve shows early-time peak pre-existing distance moduli. magnitude difference is ~-0.6 mag.
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by”
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by” How did their optical twinness at nebular phases affect our progenitor scenario interpretation for these SNeIa? The nucleosynthetic products appear to be in similar amounts in both SNe Ia -- there is no evidence for excessive stable Ni in 2011by. If their distance moduli are incorrect, they could have reached the same peak brightness, and synthesized the same amount of 56 Ni. Timmes et al. (2003): Can get a small change in M( 56 Ni) for a large change in abundance with sub-solar metallicity for both progenitor systems (e.g. Z fe =0.03 and Z by =0.90 --> M(56Ni) ~0.05 M).
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by” How did their optical twinness at nebular phases affect our progenitor scenario interpretation for these SNeIa? The nucleosynthetic products appear to be in similar amounts in both SNe Ia -- there is no evidence for excessive stable Ni in 2011by. Alternative metallicity models to Lentz: ▪ Walker models (similar, higher metallicity, less NUV flux) ▪ Sauer 2008 (opposite effect, higher metallicity, more NUV flux from scattering) All metallicity models actually predict more spectral changes than just NUV flux.
Twin Type Ia Supernovae Graham et al. (2015) “Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by” How did their optical twinness at nebular phases affect our progenitor scenario interpretation for these SNeIa? The nucleosynthetic products appear to be in similar amounts in both SNe Ia -- there is no evidence for excessive stable Ni in 2011by. Affect optical flux or spectral features? Alternatives to metallicity that affect NUV flux: ▪ radial distribution of nucleosynthetic products ▪ steeper light curve rise ▪ viewing angle (even if ignition points isotropic) ▪ high-velocity photospheric lines ▪ difference in kinetic energy and/or ejecta mass ▪ changes silicon line velocity gradient ▪ outer layer radial density gradient *Central density* and *total mass* also affect the 56 Ni in a way correlated with progenitor metallicity.
SN Ia 2011fe At ~1000 Days Graham et al. (2015) “ Constraining the Progenitor Companion of the Nearby Type Ia SN 2011fe with a Nebular Spectrum at +981 Days ”
SN Ia 2011fe At ~1000 Days
SN Ia 2011fe At ~1000 Days [Fe III] line is gone after 2 years
SN Ia 2011fe At ~1000 Days Potentially Na I D at the location of now-declined [Co III]; models suggest Na I D flux would be negligible and only potentially seen at late times.
SN Ia 2011fe At ~1000 Days Continued redward migration of all peaks in nebular phase spectra.
SN Ia 2011fe At ~1000 Days See also e.g., Shappee et al. (2013) Pakmor et al. (2008) Podsiadlowski (2003) , & (2013)
SN Ia 2011fe At ~1000 Days
SN Ia 2011fe At ~1000 Days
SN Ia 2011fe At ~1000 Days Alternative method: Blackbody continuum flux suppresses the amplitude of spectral features, so the amount of flux variance on the characteristic velocity scale of SNeIa (i.e. 10000 km/s) could also indicate a BB contribution.
Intracluster Supernovae Image credit: Dr. Alex H. Parker, NASA, and SDSS.
Intracluster Supernovae Sand et al. (2011) “Intracluster Supernovae in the Multi-Epoch Nearby Cluster Survey” m g >-12.47 m g >-11.15 *91bg-like m r >-13.04 m r >-11.68 m g >-12.54 m g >-11.72 m r >-12.56 m r >-12.37
Intracluster Supernovae Also <3 σ of the cluster velocity dispersion, | Δ v| < 3000 km/s. 19 hosted Number of SN 4 hostless Host Offset in R e
Intracluster Supernovae But Are They Truly Hostless? Deep stacks of our SN-free CFHT images leave up to 2% of the stellar mass in low-mass galaxies undetected. If the SNIa rate per unit mass is the same in red sequence galaxies and among IC stars… ...then of our 23 cluster SNeIa, ~0.5 might be hosted by the 2% in undetected galaxies. This is an important question because: 1. A rate enhancement in low-mass or globular cluster hosts has implications for the progenitor scenario. 2. IC stars are uniformly old, >2 Gyr, providing independent confirmation that progenitors are truly old.
Intracluster Supernovae CFHT HST CFHT HST r=0.5" r=0.5" r=1.0" r=1.0" SN SN SN SN r=0.69" r=0.69" r=1.20" r=1.20" G N N N N Abell 1650 Abell 1650 Abell 85 Abell 85 2.0" 2.0" 2.0" 2.0" CFHT r’ HST 606W+814W CFHT r’ HST 606W+814W 3.14 kpc 3.14 kpc 2.38 kpc 2.38 kpc 2009-12-14 2013-01-25 2009-06-18 2013-09-18 E E E E SN SN SN SN r=0.93" r=0.93" r=1.02" r=1.02" E E Abell 399 Abell 399 Abell 2495 Abell 2495 E E 2.0" 2.0" 2.0" 2.0" N N CFHT r’ HST 606W+814W CFHT r’ HST 606W+814W 3.0 kpc 3.0 kpc 2.36 kpc 2.36 kpc 2009-01-27 2013-12-04 2009-05-23 N 2013-10-04 N CFHT HST CFHT HST
Intracluster Supernovae CFHT HST CFHT HST r=0.5" r=0.5" r=1.0" r=1.0" SN SN SN SN r=0.69" r=0.69" CFHT deep stacks leave ~2% of the total stellar r=1.20" r=1.20" mass in cluster dwarf galaxies undetected. G HST deep stacks leave ~0.2% of the total stellar mass in cluster dwarf galaxies undetected. N N N N Abell 1650 Abell 1650 Abell 85 Abell 85 2.0" 2.0" 2.0" 2.0" CFHT r’ HST 606W+814W CFHT r’ HST 606W+814W 3.14 kpc 3.14 kpc 2.38 kpc 2.38 kpc 2009-12-14 2013-01-25 2009-06-18 2013-09-18 E E E E This depends on adopted slope of the galaxy luminosity function. SN SN SN SN r=0.93" r=0.93" r=1.02" r=1.02" All but bottom left have no source detected… let’s take a closer look at the bottom left HST image. E E Abell 399 Abell 399 Abell 2495 Abell 2495 E E 2.0" 2.0" 2.0" 2.0" N N CFHT r’ HST 606W+814W CFHT r’ HST 606W+814W 3.0 kpc 3.0 kpc 2.36 kpc 2.36 kpc 2009-01-27 2013-12-04 2009-05-23 N 2013-10-04 N CFHT HST CFHT HST
Intracluster Supernovae M V = -8.4, M I = -9.8 0.5" 0.59 kpc SN Not likely to be: r=0.31" -- a chance alignment with a star, E background galaxy, or cluster galaxy -- late-time emission from the SNIa F Is consistent with: -- a low-mass red sequence galaxy Abell 399 -- a globular cluster (GC) HST 606W+814W If the rate per unit mass is the same in dwarfs/GC, surface density estimates find that a GC is more likely at this location due to the nearby elliptical.
Intracluster Supernovae Implications for SNeIa regarding... … rates in low-mass red sequence galaxies. They may be enhanced by a factor of ~5. (~55 if 1 of our IC SNeIa are in the ~0.2% of stellar mass below HST limits.) … rates in globular clusters. May be enhanced by a factor of ~25. ~The level in models of binary formation, and less than current constraints. … progenitor scenarios. Some SNIa progenitors are >2 Gyr old.
Recommend
More recommend
