The Impact of Reionization on Dwarf Galaxies Oliver Elbert James - PowerPoint PPT Presentation

The Impact of Reionization on Dwarf Galaxies Oliver Elbert James Bullock 
 Jose Oñorbe Alex Fitts Mike Boylan-Kolchin Image: wikipedia

Absolute Basics • First H, then He • Completes by z = 6-10 • (Probably) Caused by Pop III stars • Minor impact on “large” galaxies

What About Small Galaxies? 5 3 2 Redshift 0.5 0.25 Simulated UFDs UFD 10 6 M * (M sun ) 10 5 Simulated Classical Dwarfs 10 4 Cumulative SFH 10 3 10 9 10 10 12 10 8 6 4 2 M halo (M sun ) Age (Gyr) Wheeler, Elbert +2015

UFDs are UV Quenched 10 5 Cumulative Stellar Mass [M � ] 10 4 10 9 M ⊙ 10 3 Normal Reionization No Reionization 0 1 2 3 4 Time [Gyr] But what about larger dwarfs?

Large Sample to Explore Suite of 12 dwarf galaxies Suite of 12 dwarf galaxies, same halo mass M * DMO + Hydro sims z Fitts, Elbert +2016

Classical Dwarfs Can Be A ff ected Fitts, Elbert +2016

Uncertainty in Reionization History Use simulations to explore! Oñorbe+2016

Dwarfs Strongly A ff ected 10 8 10 7 10 6 M ? [M � ] 10 5 10 4 10 3 Early Reionization Late Reionization 10 2 10 8 10 9 10 10 M vir [M � ]

Dwarfs Strongly A ff ected 10 8 In 10 9 M ⊙ halos: 10 7 10 6 more than M ? [M � ] 2x more 10 5 galaxies 10 4 larger M * 10 3 Early Reionization Late Reionization 10 2 10 8 10 9 10 10 M vir [M � ]

Dwarfs Strongly A ff ected 10 8 In 10 9 M ⊙ At 10 10 M ⊙ : halos: 10 7 More similar 10 6 more than M * M ? [M � ] 2x more 10 5 galaxies 10 4 larger M * 10 3 Early Reionization Late Reionization 10 2 10 8 10 9 10 10 M vir [M � ] No guarantee of more or less star formation!

Suppression Mass Threshold Fixed 14 12 Halos Youngest Stellar Age [Gyr] become UV 9 suppressed around 6 3-5 x 10 9 M ⊙ 3 Early Reionization 1 Late Reionization 10 8 10 9 10 10 M vir [M � ]

Still Significant for Classical Dwarfs 10 8 Cumulative Stellar Mass [M � ] 10 7 10 10 M sun 10 6 Early Reionization Late Reionization 10 5 0 2 4 6 8 10 12 14 Time [Gyr]

Still Significant for Classical Dwarfs 10 8 10 7 10 7 Cumulative Stellar Mass [M � ] Cumulative Stellar Mass [M � ] Cumulative Stellar Mass [M � ] 10 7 10 6 10 6 10 6 10 5 10 5 Early Reionization Faucher � Giguere 09 Early Reionization Late Reionization Onorbe Late Late Reionization 10 5 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Time [Gyr] Time [Gyr] Time [Gyr] 10 8 10 6 10 7 Cumulative Stellar Mass [M � ] Cumulative Stellar Mass [M � ] Cumulative Stellar Mass [M � ] 10 7 10 5 10 6 10 6 10 5 10 4 Early Reionization Faucher � Giguere 09 Early Reionization Late Reionization Onorbe Late Late Reionization 10 5 10 4 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Time [Gyr] Time [Gyr] Time [Gyr]

Still Significant for Classical Dwarfs 1 . 0 1 . 0 1 . 0 Cumulative Star Formation History Cumulative Star Formation History Cumulative Star Formation History 0 . 75 0 . 75 0 . 75 0 . 5 0 . 5 0 . 5 0 . 25 0 . 25 0 . 25 Early Reionization Faucher − Giguere 09 Early Reionization Late Reionization Onorbe Late Late Reionization 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Time [Gyr] Time [Gyr] Time [Gyr] 1 . 0 1 . 0 1 . 0 Cumulative Star Formation History Cumulative Star Formation History Cumulative Star Formation History 0 . 75 0 . 75 0 . 75 0 . 5 0 . 5 0 . 5 0 . 25 0 . 25 0 . 25 Faucher − Giguere 09 Faucher − Giguere 09 Early Reionization Onorbe Late Onorbe Late Late Reionization 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Time [Gyr] Time [Gyr] Time [Gyr]

Conclusions • Reionization is complicated: • Quenches UFDs 9 seems like threshold for this • M h ~4 x 10 • Changing reionizing strength may move this? • Later reionization gives more galaxies • Smallest “classical “ dwarfs near Okamoto-like suppression mass • Can explain potential quenched field dwarfs • Even above this, SFH is impacted • Factor ~ 2 change in M * , variety of formation times • Dwarfs are snowflakes too, each responds in its own way

Thank You

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UV Feedback Heat input from Reionization ~ 20,000 K Fitts, Elbert +2016