A Phenomenological Look at Type Ia Supernovae from Keck/DEIMOS - PowerPoint PPT Presentation

A Phenomenological Look at Type Ia Supernovae from Keck/DEIMOS Spectroscopy Evan Kirby Caltech Credit: DOE NNSA ASC/Alliance Flash Center at the University of Chicago

Collaborators Ivanna Escala Justin Xie Rachel Guo Caltech The Harker School Irvington High School Andrew Wetzel UC Davis 2/17

Elements you will hear about: ● Magnesium ( Z =12): used to infer the rate of star formation and hence chemical evolution ● Iron ( Z =26): produced somewhat by core collapse SNe and copiously by Type Ia SNe ● Cobalt ( Z =27) and nickel ( Z =28): the stable versions have more neutrons than protons, requiring a neutron excess to produce them ● Chromium ( Z =24): a boring iron-peak element 3/17

The [Mg/Fe] ratio indicates the star formation timescale. [Mg/Fe] Type II Type Ia Types II+Ia [Fe/H]

Draco was terrible at its job. [α/Fe] 〉 [Ti/Fe] [Ca/Fe] [Si/Fe] [Mg/Fe] 〈 M * = 3 × 10 5 M ⊙ Draco [Fe/H] EK et al., 2011, ApJ, 727, 79 5/17

Sculptor was slightly better at its job. [Mg/Fe] Sculptor M * = 2 × 10 6 M ⊙ [Si/Fe] [Ti/Fe] [Ca/Fe] EK et al., 2011, ApJ, 727, 79 [α/Fe] 〉 〈 [Fe/H] 6/17

Sub- M Ch Type Ia’s struggle to make stable Co and Ni. M Ch detonation M Ch with delayed detonation-to-deflagration transition (DDT) Sub- M Ch detonation Seitenzahl & Townsley 2017, arXiv:1704.00415 7/17

We measured Cr, Co, and Ni from existing DEIMOS spectra. 8/17

We measured Cr, Co, and Ni from existing DEIMOS spectra. 9/17

Sculptor’s chemical evolution is easy to interpret. Sculptor dwarf galaxy Core collapse [Mg/Fe] simulated yield Type Ia simulated yield [Cr/Fe] [Co/Fe] [Ni/Fe] [Fe/H] 10/17

Type Ia’s make little of the heavier Fe-peak elements. f Ia Core collapse [Mg/Fe] simulated yield Type Ia simulated yield [Cr/Fe] [Co/Fe] Core collapse inferred yield Type Ia inferred yield [Ni/Fe] [Fe/H] 11/17

Leo II shows a similar pattern to Sculptor. f Ia Core collapse [Mg/Fe] simulated yield Type Ia simulated yield [Cr/Fe] [Co/Fe] Core collapse inferred yield Type Ia inferred yield [Ni/Fe] [Fe/H] 12/17

Sagittarius shows the same pattern. Sagittarius MW disk [Cr/Fe] MW bulge MW halo Hasselquist et al. 2017, ApJ, in press, arXiv:1707.03456 [Co/Fe] [Ni/Fe] [Fe/H] 13/17

The data slightly favor Chandrasekhar- mass delayed detonations. dSphs M ch M ch sub- M Ch pure deflagration delayed detonation (W7) (DDT) [Cr/Fe] 0.0 –0.28 –0.10 +0.25 [Co/Fe] –0.5 –0.39 –0.59 < –1 [Ni/Fe] –0.2 +0.44 +0.21 –0.71 M Ch (W7): model of Maeda et al. 2010, ApJ, 712, 624 M ch (DDT): Seitenzahl et al. 2013, MNRAS, 429, 1156 sub- M Ch : Papish & Perets 2016, ApJ, 822, 19 14/17

Your simulation doesn’t have enough Type Ia supernovae. [Fe/H] [Si/Fe] [Fe/H] log ( M * / M ⊙ ) Escala, EK, Wetzel, Hopkins et al., in prep. Originally with Mannucci et al. (2006) delay time distribution: (0.19-0.66) ± 10 –3 SN M ⊙ –1 Now with with Maoz & Graur (2017) rate: 1.3 ± 10 –3 SN M ⊙ –1 15/17

I can’t wait for Subaru PFS! Walker et al. 2009, ApJ, 704, 1274 Walker et al. 2009, ApJ, 704, 1274 Walker et al. 2009, AJ, 137, 3100 Walker et al. 2009, AJ, 137, 3100 16/17

Conclusions ● Type Ia supernovae dominated the chemical evolution of dwarf galaxies. ● The Ia yields inferred from Keck/DEIMOS measurements of iron- peak elements are solar for [Cr/Fe] but sub-solar for [Co/Fe] and [Ni/Fe]. ● These results favor Chandrasekhar-mass delayed detonations . [Fe/H] ● Simulations with higher Ia rates (>1 per 1000 M ⊙ ) better reproduce dwarf galaxy abundance measurements. log ( M * / M ⊙ ) 17/17