Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter Bild på kvasar och LSBG? Erik Zackrisson

Outline Dark matter Quasars Low Surface Brightness Galaxies 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

Dark Matter Dark matter Luminous matter

First detection of dark matter Top 10 most important problems in science Fritz Zwicky (1933): Dark matter in the Coma Cluster

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

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

Dark Matter Halos II Luminous galaxy Dark halo Not a ring – a filled sphere! Dark halo

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)

Cold dark matter and the evolution of structure

Cold dark matter and the evolution of structure II

Cold Dark Matter Halos Central density cusp predicted by Observed Density Density profiles R Dark matter halo

Quasars

Gravitational lensing

Gravitational lensing II

Microlensing Made Simple Microlensing more complicated than other forms of lensing because ML is time-dependent Opportunity and challenge (when both distance and velocity unknown) Obs! Fel bild!

Microlensing Made Simple II

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

The dark matter puzzle solved? Mcompact 10-3 Msolar Almost all of the dark matter in this form Primordial black holes? Bild på Hawkins bok

Expansion of the Universe Viktigt inför presentationen av Big Bang Den jäsande degen… Inte bara verkar universum växa, expansionen verkar gå snabbare och snabbare också – expansionen accelererar

Redshifts High z  Large distance Low z  Small distance Spooky picture… High z  Large distance Low z  Small distance

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

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

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

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

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

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

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

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