1 / 19

Dwarf Spheroidals and Reionization: Is There a Link?

Dwarf Spheroidals and Reionization: Is There a Link?. Nick Gnedin. Co-starring:. Massimo Ricotti (UMD). Our backyard. Who Commands Dwarf Galaxies?. Looks familiar?. Reionization? Formation of LG? Just a fluke?. Grebel 1998. Life of a Dwarf Galaxy. “True fossil”. “Polluted

larya
Download Presentation

Dwarf Spheroidals and Reionization: Is There a Link?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dwarf Spheroidals and Reionization:Is There a Link? Nick Gnedin

  2. Co-starring: Massimo Ricotti (UMD)

  3. Our backyard

  4. Who Commands Dwarf Galaxies? Looks familiar? • Reionization? • Formation of LG? • Just a fluke? Grebel 1998

  5. Life of a Dwarf Galaxy “True fossil” “Polluted fossil” “Survivor” z ~ 6 reionization z ~ 3 Local Group forms z = 0 today Time

  6. Observer’s view (Grebel 2005)

  7. 1 chimp 25 pc @z=8 900 M8 Resolving All • Reionized @ z=9 • Stopped @ z=8.3 Space Simulation Simulation Local Group @z=0 Mass

  8. Fornax twins Born: 2003 CE Born: 13,283,456,789 BCE

  9. Who Is Who? Survivors Polluted fossils Virtual dwarfs True fossils Real dwarfs Too bright & too large to be fossils

  10. Star Formation

  11. Metallicity

  12. Kinematics

  13. Metallicity Spread I

  14. Metallicity Spread II

  15. IC 10 IC 1613 IC 5152 LMC M32 NGC 55 NGC 147 NGC 185 NGC 205 NGC 3109 NGC 6822 Sextans A Sextans B SMC WLM Carina DDO 210 GR8 Fornax Leo A Leo I Leo II LGC 3 Pegasus Sagittarius And I And II And III And V And VI Antlia Cetus Draco KKR 25 Phoenix Sculptor Sextans Tucana Ursa Minor Dividing the Loot Survivors Luminosity True fossils Polluted fossils

  16. Prediction “True fossils” (like And I and And II) are about 1.5 Gyr older than “survivors” (like WLM or NGC3109) $ Horizontal Branch Index can test this!

  17. Const survival probability Best fit Lilliput Spheroidals?

  18. Conclusions • Virtual galaxies formed before reionization resemble lowest mass dwarf spheroidals in all observable properties – is it a coincidence? • Possible tests: • spatial distribution with the Local Group (need to relate z=0 and z>6) • metallicity spread (but virtual dwarfs have it too) • alpha-to-iron ratio (no signatures of SNIa in dSphs – Tsujimoto 2005) • relative ages using the HB index (perhaps, the best method) • existence of “lilliput spheroidals”. Sextans Ursa Major

  19. The End

More Related