Constraining general modifications of gravity during Reionization

Transcription

1 Constraining general modifications of gravity during Reionization Caroline Heneka Scuola Normale Superiore (SNS), Pisa Rencontres de Moriond La Thuile, March 17-24, 2018 based on: CH+ ApJ, 848 (2017) & arxiv:1804.xxx to be submitted

2 Introduction (Also) during Reionization: Gravity (and astrophysics) govern structure formation Which model of gravity / what cosmology? Which observables at these redshifts? Explore nature of Λ / DE / MG General properties / parametrizations w 0 w a c s µ Y Use wide range of scales (test scale- dependence)

3 Reionization high z: linear growth, simpler astrophysics(?) z 6 Image Credit:

4 Intensity Mapping What is the (large scale) structure of the Universe? To find out, we can identify individual sources of emission. Image: Courtesy of Asantha Cooray Image Credit:

5 Intensity Mapping What is the structure of the Universe? What are properties of galaxies / ionising sources?? To find out, we can identify individual sources of emission. OR We can sum all the emission in large areas and measure fluctuations (IM). Image: Courtesy of Asantha Cooray Image Credit:

6 Reionization Mesinger et al TS >> T Spin 21- cm temperature: T 1 = S TS < T T 1 + x T 1 + x c TK x + xc TS T

7 Intensity Mapping Cosmology from EoR/Cosmic Dawn with the SKA (Pritchard et al. 15) z=8 z=20 BUT

8 Simulations: 21 cm signal 21cm FAST (DexM) semi-numerical [Mesinger et al. 10] ionization xhi fcoll (x, M, z) 1 (filtering) density (+ velocity) Tb (Zel dovich approximation) Offset 21- cm brightness temperature T b TS T Tb ( ) = 1 e 0 1+z / xhi (1 + nl ) H dvr /dr + H Fiducial Cosmology: Planck

9 Parametrize GR- modifications Growth function: G (z,k) = m (z,k) / (0,k) via linear perturbation evolution: m + E0 0 E m = 3 m 2 a 3 E 2 m,0y with IC: = 0 in/ in Amendola et al. 2013, Taddei & Amendola =d/d log a

10 Parametrize GR- modifications Growth function: G (z,k) = m (z,k) / m (0,k) Parameter / free functions via linear perturbation evolution: m + E0 0 E m = 3 m 2 a 3 E 2 m,0 Y MG with IC: = MG 0 in/ in Amendola et al. 2013, Taddei & Amendola w 0,w a 0 =d/d log a

11 Parametrize GR- modifications Horndeski form, quasi- static: Y = h 1 1+(k/k p ) 2 h 5 1+(k/k p ) 2 h 3 time- dependent h i IC, in principle scale- dependent: = (k) = 0 in/ in GR: Y =1 & 0 in/ in =1 Amendola et al. 2013, Taddei & Amendola =d/d log a

12 Effect of varying Y z=10 Y=0.99 Y=1.0 Y=1.01 xh = xh = xh = [Normalized to same growth at CMB] C. Heneka & L. Amendola, 2018, in prep.

13 Effect of varying Y z=7 Y=0.99 Y=1.0 Y=1.01 x H 5 x H 0.30 x H = = =0.846 [Normalized to same growth at CMB] C. Heneka & L. Amendola, 2018, in prep.

14 Effect of varying Y + cosmic variance, thermal noise, instrumental sensitivity S/N: up to ~O(100) C. Heneka & L. Amendola, 2018, in prep.

15 Fisher (SKA): m, w0, wa, Y, - + foreground removal -0.6 w Fij = wa -1.6 z,k a kk 2 4 Cov 1 (z, 2 21,l (z, kk dc E(z) 0 k? dh (1 + z) w (0.144) (z, k) (0.016) 1.6 Y X wa 0.06 (0.072) Y (0.018) 0.06 (0.126) Wm w wa a [For 5 z- bins z=6-10] C. Heneka & L. Amendola, 2018, in prep.

16 Fisher (SKA): m,w 0,w a,y, For cosmological parameters only: P ij = C ij p Cii C jj Y the optimist Plus reionization parameters: Y order % errors on other parameters Tomography is key C. Heneka & L. Amendola, 2018, in prep.

17 Fisher (SKA): m,w 0,w a,y, For cosmological parameters only: P ij = C ij p Cii C jj Y Shot-noise high-k cut: Y C. Heneka & L. Amendola, 2018, in prep.

18 Fisher (SKA): m,w 0,w a,y, From cosmological parameters only: P ij = C ij p Cii C jj Y Cut of non-linear scales: Y Important to model (mildly) non-linear scales C. Heneka & L. Amendola, 2018, in prep.

19 Cosmology from EoR/Cosmic Dawn with other lines e.g. Ly- alpha Y up Y down neutral ionized vs.

20 Conclusion Study of Reionization: Intensity mapping Avenue to constrain cosmology / MG %- precision even for extended models within reach Tomography lifts degeneracies with astrophysics Important to model (mildly) non- linear scales a Y Ongoing & Upcoming: (k/kp ) h5 Test scale- dependency Y = h (k/kp ) h3 Combine with other probes Model the (mildly) non- linear regime caroline.heneka@sns.it Wm w wa a

21 .. Thank you