Hunting for dark matter in the forest (astrophysical constraints on warm dark matter)

Hunting for dark matter in the forest (astrophysical constraints on warm dark matter) ICC, Durham! with the Eagle collaboration: J Schaye (Leiden), R Crain (Liverpool), R Bower, C Frenk, & M Schaller (ICC) and A Garzilli (Leiden), A Boyarsky (Leiden) 1

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 2

Dark matter: Do we need it? What is it? Where is it? How much? The Dark Matter Rap: Cosmological History for the MTV Generation by David Weinberg! My name is Fritz Zwicky, I can be kind of prickly, This song had better start by giving me priority. Whatever anybody says, I said in 1933. Observe the Coma cluster, the redshifts of the galaxies imply some big velocities. They're moving so fast, there must be missing mass! Dark matter.! Dark matter: Do we need it? What is it? Where is it? How much? Do we need it? Do we need it? Do we need it? Do we need it? 3

Dark matter: Do we need it? What is it? Where is it? How much? Cosmological History for the Twitter Generation Galaxies and how they are distributed in the Universe require the existence of mass that does not shine. The nature of this dark matter is presently unknown. Vera Rubin 4

Planck CMB map (z=1000) 5 CfA map of galaxies (z=0)

Galaxy clustering: SDSS 2dF 6

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 7

d e rv e s ob l i M m u i n l en Springel +05 movie:volker Springel 8

Millennium simulation + galaxy formation model movie: John Helly (Durham) 9

Galaxy stellar mass function versus dark matter halo mass function Abundance galaxies Dark halos (const M/L) Stellar Mass 10 Halo Mass Bower+06

Galaxy formation efficiency Stellar mass / halo mass halo mass / solar mass 11 Behroozi +13

1504 3 Gadget 3 simulation (100 Mpc) 3 volume baryonic mass 10 6 Msun Calibrated to z=0 stellar MF Local subgrid physics 12

Dark matter: what do we need from it? non-baryonic, small cross section, does not radiate (much): how about neutrinos? actually: that won t make galaxies! Zel dovich 13 Peebles

The cold dark matter power spectrum as computed by Bond & Efstathiou 87 and as measured by Planck 14

NFW in profile NFW profile: 15

Eagle 16 Schaller +15

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 17

18 Aquarius: Springel+08

Three (four?) issues with CDM: WDM halo of MW-like galaxy CDM halo of MW-like galaxy 19 Springel+08

All these can be solved be warm dark matter CDM WDM 20

1 Observed voids are more empty than in cold dark matter (Peebles) 21

Eagle Which dark matter halos are observable? halos observable in neutral hydrogen Abundance simulated observed halo mass 22 Sawala +13

2: Cold dark matter predicts too many satellites cluster galaxy 23

CDM halo Milky Way s satellites WDM halo Credit: J. T. A. de Jong 24

Eagle Dark matter view (halos) Observable view (galaxies) 25 Sawala+14

Eagle Galaxies vs halos M31 MW LG halos halos halos Galaxies 26 Sawala+14

3 Massive substructures are too big not to host satellite Measure halo mass of observed satellites 27

Eagle Eagle galaxy No TBTF problem: halos lose mass 28 Sawala+16

4: Cold dark matter halos are cusped, observed haloes have cores. Oh +, 08 29

Does WDM generate cores? 30 Yes! But they are too small

Eagle 31

Eagle 32

33

Feedback can generate cores Pontzen & Governato 13 Governato+12 34

35

1.Voids 2.Number of satellites 3.Too big to fail (massive substructures) 4.cores vs cusps No (?) issues with CDM when including galaxy formation physics Abu galaxies Dark halos (const M/L) 36 Stell Hal

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 37

Probing dark matter with quasars Nature, 63 z=7.1 ULAS J1120+064 Mortlock +, Nature 11 38

Intervening absorption in quasar spectra 39

A (very simple) intrinsic quasar spectrum Flux observed wavelength Hydrogen atom 40

Expected observed spectrum due to intervening absorption complete absorption Flux complete transmission observed wavelength 41

Conclusion: the Universe is highly ionised Ionization rate from galaxies & quasars as computed by Haardt & Madau 42

Intervening absorption Fan+03 43 Fan+01, 06

*Much* more absorption at higher redshifts a lot of absorption complete transmission Nearby quasar Distant quasar 44

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 45

Photo-ionisation also heats gas: photo-heating Resulting temperature-density relation Temperature / K Density / mean density 46 Garzilli+15

Line broadening: thermal broadening large N small N small N large N 47

Line broadening: Jeans filtering 48 Theuns +00

Line broadening = smoothing operation introduces a cut-off in the power spectrum Eagle line width Jeans filtering thermal broadening line strength 49 Garzilli + 15

linear transfer function Flux power spectrum cut-off cut-off Croft +99 Is the observed cut-off due to WDM? Or due to the temperature of the gas? 50

Mock quasar spectrum Viel+13 51

Flux power spectra at different redshifts observed Mock 52 Viel+13

(Lack of) degeneracy between thermal and WDM cut-off 53 Viel+13

Contents: Dark matter: what is it, where is it, do we need it? How much? Dark matter: what do we need from it? Cold dark matter! Dark matter: did we over do it? Warm dark matter! Interlude: quasar spectra Dark matter: cut-off in flux power spectra: WDM or thermal Future: lensing, and Relhics 54

Future: gravitational lensing - astro-ph 1512.06507 satellites (again) stellar streams Relhics Eagle Relhics Lensing: Vegetti +12 55 Benitez-Llambay+17

I want to be involved! 56

Hunting for dark matter in the forest (astrophysical constraints on warm dark matter) ICC, Durham! with the Eagle collaboration: J Schaye (Leiden), R Crain (Liverpool), R Bower, C Frenk, & M Schaller (ICC) and A Garzilli (Leiden), A Boyarsky (Leiden) 57