Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter

1. Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter Erik Zackrisson

2. Outline • Dark matter • Dark matter halos • Baryonic and non-baryonic dark matter • Cold dark matter • Quasars • Gravitational lensing • Redshift • Low Surface Brightness Galaxies • Rotation curves • Summary of Results

3. Dark Matter Dark matter Luminous matter

4. First detection of dark matter Fritz Zwicky (1933): Dark matter in the Coma Cluster

5. The Dark Matter Problem ~2% (Luminous) ~98% (Dark)

6. Dark Matter Halos I Galaxy  Stars + Gas + Dust + Supermassive Black Hole + Dark Matter

7. Dark Matter Halos II Luminous galaxy Dark halo

8. Baryonic & Non-Baryonic Dark Matter Baryonic matter: ~15% • Example: Stars, gas clouds, planets… • Missing: ~ 35% Non-baryonic matter: ~85% • Example: Axions, neutralinos, primordial black holes… • Missing: ~ 100% • Best model: Cold Dark Matter (CDM)

9. Cold dark matter and the evolution of structure

10. Cold dark matter and the evolution of structure II

11. Cold Dark Matter Halos Central density cusp predicted by cold dark matter R Observed Density R Dark matter halo

12. Quasars

14. Gravitational lensing

15. Gravitational lensing II

16. Microlensing Made Simple Obs! Fel bild!

17. Microlensing Made Simple II

18. Claim: The long-term optical variability of quasars is quased by microlensing Hawkins, M.R.S. (1993, 1996, 1997, 2000, 2001, 2002, 2003)

19. The dark matter puzzle solved? • Mcompact 10-3 Msolar • Almost all of the dark matter in this form • Primordial black holes?

20. Expansion of the Universe

21. Redshifts High z  Large distance Low z  Small distance

22. Claims of non-cosmological redshifts z1 z2 Low-z galaxy with pairs of high-z quasars (with z1z2) aligned along minor axis Low-z galaxy surrounded by overdensity of high-z quasars

23. Ejection scenarios ? ? ? New galaxy (?), very low redshift (z1) ? ? Bright quasar, low redshift (>z1) Faint quasar, high redshift (>>z1) Local galaxy, very low redshift (z1)

24. Low Surface Brightness Galaxies Examples of Target Galaxies The Very Large Telescope

25. The Central Mass Budget High Surface Brightness Galaxies Low Surface Brightness Galaxies Dark matter Luminous matter Dark matter Luminous matter

26. Rotation Curves CDM prediction Vrot Density Observed Radius Radius Spectroscopy → Rotation Curve → Density Profile

27. Results Paper I • Uncertainties in the typical quasar size  Quasar variability cannot easily be used to constrain dark matter at the current time Paper II • Microlensing cannot explain the long-term optical variability of quasars – Hawkins is wrong! Paper III • Non-cosmological redshift scenarios involving quasar ejection can be tested with observations of quasar host galaxies made a small telescope

28. Results II Paper IV • The bluest low surface brightness galaxies can be used to test hierarchical galaxy formation models – provided that we can derive their ages • The star formation rate of the bluest low surface brightness galaxies cannot have been constant or increasing – unless the stellar initial mass function is unusual Paper V • The density profiles of the dark halos surrounding the bluest low surface brightness galaxies are in conflict with the Cold Dark Matter predictions

29. Errata • Spikblad: Polhemssalen  Polhemsalen • Page v: optical long-term  long-term optical • Page 3: as the ray crossed  as its ray grazed • Page 24 (twice): reflectance  reflection • Page 33: z  2—3  z  2—4 • Page 35: the latter variations  these variations • Page 35: hoever are  are however • Page 37: by fast rise  by a fast rise • Page 44: 1012—1014 m  1012—31013 m • Page 56: disk by  disk is given by • Page 69: ett par procent  några få procent • Page 69: välkända astronomiska objekt  välkända typer av astronomiska objekt • Page 69: både vår och andra  både vår egen och andra • Paper I, page 26, column 2, paragraph 1: higher angular size distance  higher light travel time distance • Paper V, page 8: Division line should not be dashed