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

2/17

Collaborators

Ivanna Escala

Caltech

Rachel Guo

Irvington High School

Justin Xie

The Harker School

Andrew Wetzel

UC Davis

3/17

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

[Fe/H] [Mg/Fe]

The [Mg/Fe] ratio indicates the star formation timescale.

Type II Type Ia Types II+Ia

5/17

Draco was terrible at its job.

[Fe/H] [Ti/Fe] [Ca/Fe] [Mg/Fe] [Si/Fe] 〈 [α/Fe]〉

Draco M* = 3 × 105 M⊙ EK et al., 2011, ApJ, 727, 79

6/17

Sculptor was slightly better at its job.

[Fe/H] [Ti/Fe] [Ca/Fe] [Mg/Fe] [Si/Fe] 〈 [α/Fe]〉

Sculptor M* = 2 × 106 M⊙ EK et al., 2011, ApJ, 727, 79

7/17

Sub-MCh Type Ia’s struggle to make stable Co and Ni.

Seitenzahl & Townsley 2017, arXiv:1704.00415

MCh detonation Sub-MCh detonation MCh with delayed

detonation-to-deflagration transition (DDT)

8/17

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

9/17

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

10/17

Sculptor’s chemical evolution is easy to interpret.

[Fe/H] [Mg/Fe] [Cr/Fe] [Co/Fe] [Ni/Fe]

Core collapse simulated yield Type Ia simulated yield Sculptor dwarf galaxy

11/17

Type Ia’s make little of the heavier Fe-peak elements.

[Fe/H] [Mg/Fe] fIa [Cr/Fe] [Co/Fe] [Ni/Fe]

Core collapse simulated yield Type Ia simulated yield Core collapse inferred yield Type Ia inferred yield

12/17

Leo II shows a similar pattern to Sculptor.

[Fe/H] [Mg/Fe] fIa [Cr/Fe] [Co/Fe] [Ni/Fe]

Core collapse simulated yield Type Ia simulated yield Core collapse inferred yield Type Ia inferred yield

13/17

Sagittarius shows the same pattern.

Hasselquist et al. 2017, ApJ, in press, arXiv:1707.03456 Sagittarius MW disk MW bulge MW halo

[Fe/H] [Cr/Fe] [Co/Fe] [Ni/Fe]

14/17

The data slightly favor Chandrasekhar- mass delayed detonations.

dSphs Mch

pure deflagration (W7)

Mch

delayed detonation (DDT)

sub-MCh [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 MCh (W7): model of Maeda et al. 2010, ApJ, 712, 624 Mch (DDT): Seitenzahl et al. 2013, MNRAS, 429, 1156 sub-MCh: Papish & Perets 2016, ApJ, 822, 19

15/17

Your simulation doesn’t have enough Type Ia supernovae.

log (M*/M⊙) [Fe/H] [Fe/H] [Si/Fe]

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

16/17

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

17/17

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.

• Simulations with higher Ia rates (>1 per

1000 M⊙) better reproduce dwarf galaxy abundance measurements.

log (M*/M⊙) [Fe/H]