Matéria escura

Aula do curso de "Introdução à cosmologia" para graduação, Prof. Rodrigo Nemmen, IAG USP.

• Razão massa luminosidade
• aglomerados de galáxias
• método das curvas de rotação
• halos de matéria escura
• lentes gravitacionais
• busca observacional por MACHOs
• WIMPs
• buscas indiretas e diretas por matéria escura, no espaço e em solo
• MOND

https://rodrigonemmen.com/teaching/introducao-a-cosmologia/

Transcript

1. Rodrigo Nemmen Matéria Escura Introdução à Cosmologia
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2. Dado um certo sistema físico, qual a massa correspondente à quantidade de radiação observada? Razão massa-luminosidade M /L
3. Exemplos: Razão massa-luminosidade Sol M/L = 1M /L ,B = 43 ton / W Estrelas 1 kpc ao redor do sistema solar hM/Li = 4M /L ,B = 170 ton / W Para estrelas: valor sensível ao tipo de estrela
4. Contando estrelas no universo à maneira cosmológica Estrelas 1 kpc ao redor do sistema solar hM/Li = 4M /L ,B = 170 ton / W ⇢⇤,0 = hM/Li j⇤,B ⇡ 5 ⇥ 108M Mpc 3 Densidade estelar: Densidade de luminosidade: j⇤,B = 1.2 ⇥ 108L ,B Mpc 3 (<100 Mpc de distância) Parâmetro de densidade estelar: ⌦⇤,0 = ⇢⇤,0 ⇢c,0 ⇡ 3.4 ⇥ 10 29kg m 3 9.1 ⇥ 10 27kg m 3 ⇡ 0.004
5. E os 96% restantes???
6. Aglomerado de galáxias Abell 2744 z = 0.3 dp = 1.2 Mpc
7. Aglomerados de galáxias As maiores estruturas do universo 50 - 1000 galáxias Massas da ordem de 1014 - 1015 massas solares
 Diâmetros típicos de 1 - 10 Mpc
8. Aglomerado de galáxias Abell 2744 Imagem no óptico z = 0.3 dp = 1.2 Mpc 6 Manos-luz
9. z = 0.3 dp = 1.2 Mpc Aglomerado de galáxias Abell 2744 Imagem em raios X
10. Aglomerado de galáxias Coma Imagem no óptico z = 0.02 dp = 102 Mpc 2 Manos-luz
11. z = 0.02 dp = 102 Mpc Aglomerado de galáxias Coma Imagem em raios X
12. Aglomerados de galáxias gás muito quente 107 - 108 K emissão em raios X via efeito Bremstrahlung
13. Trabalho pioneiro de Vera Rubin, década de 70 e 80
14. Curva de rotação da M33
15. 10 20 30 40 50 0.5 1.0 1.5 2.0 v unidades arbitrárias r (kpc) corpo rígido Curvas de rotação de galáxias simples
16. Exemplo: partículas-teste em rotação, corpo rígido
17. 10 20 30 40 50 0.5 1.0 1.5 2.0 v unidades arbitrárias r (kpc) sem matéria escura com matéria escura corpo rígido Curvas de rotação de galáxias (simplificadas)
18. Matéria escura Matéria escura Efeito da matéria escura na rotação de partículas- teste em galáxias
20. Efeito da matéria escura na rotação de partículas- teste em galáxias CHAPTER 8. DARK MAT e 8.4: The orbital speed v as a function of radius in M31. The Rubin & Ford 1970 Roberts & Whitehurst 1975 van den Berg 2000
21. Efeito da matéria escura na rotação de partículas- teste em galáxias CHAPTER 8. DARK MAT e 8.4: The orbital speed v as a function of radius in M31. The Rubin & Ford 1970 Roberts & Whitehurst 1975 van den Berg 2000
22. Matéria Escura Para explicar o movimento rápido das estrelas longe do centro das galáxias, deve existir um halo estendido de matéria escura, que teria massa 10 vezes maior do que a da matéria bariônica
23. LETTERS PUBLISHED ONLINE: 9 FEBRUARY 2015 | DOI: 10.1038/NPHYS3237 Evidence for dark matter in the inner Milky Way Fabio Iocco1,2*, Miguel Pato3,4 and Gianfranco Bertone5 The ubiquitous presence of dark matter in the Universe is today a central tenet in modern cosmology and astrophysics1. Throughout the Universe, the evidence for dark matter is compelling in dwarfs, spiral galaxies, galaxy clusters as well as at cosmological scales. However, it has been historically di￿cult to pin down the dark matter contribution to the total mass density in the Milky Way, particularly in the innermost regions of the Galaxy and in the solar neighbourhood2. Here we present an up-to-date compilation of Milky Way rotation curve measurements3–13, and compare it with state-of-the-art baryonic mass distribution models14–26. We show that current data strongly disfavour baryons as the sole contribution to the Galactic mass budget, even inside the solar circle. Our findings demonstrate the existence of dark matter in the inner Galaxy without making any assumptions about its distribution. We anticipate that this result will compel new model-independent constraints on the dark matter local density and profile, thus reducing uncertainties on direct and indirect dark matter searches, and will help reveal the structure and evolution of the Galaxy. Existing studies of the dark matter density in the inner Galaxy fall into two categories: mass modelling and local measurements. In mass modelling, the distribution of dark matter is assumed to follow a density profile inspired by numerical simulations, typically an analytic fit such as the well-known Navarro–Frenk–White27 or Einasto28 profiles, with two or more free parameters whose best- weak constraints in the innermost regions of the Milky Way, due to a combination of poor rotation curve data and large uncertainties associated with the distribution of baryons. We show that recent improvements on both fronts allow us to obtain a convincing proof of the existence of dark matter inside the solar circle. We start by presenting a new, comprehensive compilation of rotation curve data derived from kinematic tracers of the Galactic potential, which considerably improves on earlier (partial) compilations30,31. Optimized to Galactocentric radii R = 3–20 kpc, our database includes gas kinematics (HI terminal velocities3,4, CO terminal velocities5, HI thickness6, HII regions7,8, giant molecular clouds8), star kinematics (open clusters9, planetary nebulae10, classical cepheids11, carbon stars12) and masers13. This represents an exhaustive survey of the literature that intentionally excludes objects with only kinematic distances, and those for which asymmetric drift or large random motions are relevant. In total we have compiled 2,780 measurements, of which 2,174, 506 and 100 are from gas kinematics, star kinematics and masers, respectively (see Supplementary Text). For each measurement, we translate the kinematic data into a constraint on the angular velocity !c =vc /R and on the Galactocentric radius R. The upper panel of Fig. 1 shows the rotation curve vc (R) for the full compilation of data, including only statistical uncertainties (see Supplementary Text for a test of systematics on observational data). The contribution of stars and gas to the total mass of the Galaxy has historically been subject to significant uncertainties,
24. Curva de rotação da nossa galáxia ETTERS NATURE PHYSICS DOI: 10.1038/NPHYS Circular velocity (km s−1) Circular velocity (km s−1) 100 200 300 400 500 600 R 0 = 8 kpc R 0 = 8 kpc v 0 = 230 km s−1 Gas kinematics Star kinematics Masers Galactocentric radius (kpc) 0 5 10 15 20 25 30 0 50 100 150 200 250 300 Ref. 14 (E2) Ref. 14 (G2) Ref. 15 Ref. 16 Ref. 18 Ref. 17 Ref. 19 Bulge Ref. 20 Ref. 21 Ref. 22 Ref. 23 Ref. 24 Disk Ref. 25 Ref. 26 Gas Iocco et al. 2014
25. Curva de rotação da nossa galáxia ATURE PHYSICS DOI: 10.1038/NPHYS3237 LETTERS 100 R 0 = 8 kpc R cut = 2.5 kpc 20 50 Rotation curve data Baryonic bracketing −60 −40 −20 0 20 40 60 Standard NFW profile Galactocentric radius (kpc) χ2/dof 101 100 10−1 10−2 R 0 = 8 kpc v 0 = 230 km s−1 3 5 10 20 5σ Residuals (km s−1 kpc−1) Angular circular velocity (km s−1 kpc−1) Iocco et al. 2014
26. Lentes gravitacionais
28. Illustrated London News of November 22, 1919
29. Illustrated London News of November 22, 1919
30. New York Times, 10 Nov. 1919
34. http://apod.nasa.gov/apod/ap111221.html Lente gravitacional causada por uma galáxia
35. tempo fluxo t
36. Conclusões de busca por MACHOs Não há muitos objetos com M < 0.08 Msolar (anãs marrons), poucos eventos com Δt curto) <20% da massa do halo pode estar na forma de MACHOs tipicamente MMACHO > 0.15 Msolar (Δt > 35 dias) ∴ MACHOs não explicam ME, pois a massa predominante do Halo deve ser na forma de uma componente distribuída uniformemente No halo escuro da nossa Galáxia
37. Lentes gravitacionais em aglomerados de galáxias
38. Lentes gravitacionais em aglomerados de galáxias xd = 500 Mpc d = 1000 Mpc
39. Abell 2218 z=0.18 d = 770 Mpc http://hubblesite.org/newscenter/archive/releases/2001/32/image/b/
40. Candidatos a matéria escura Áxions: partículas hipotéticas com mc2~10-5 eV Buracos negros primordiais: m ~105 Msol Fundo cósmico de neutrinos (levemente massivos) WIMPs: Weakly Massive Interacting Particles partículas não-bariônicas como fotinos, gravitinos, axinos, sneutrinos, gluinos, etc. mc2 >10 GeV
42. Dark Sector of Vermions Varks Veptons Dark charge Dark charge Vosons Vluon Voton ? ? ? ? ? ? ? Dark Dark charge Dark charged Vosons ? ? ? ?
43. Busca por matéria escura no espaço: Fermi Large Area Telescope
44. m = 65 GeV m = 65 GeV Eγ = 130 GeV DM particles annihilate Gamma-ray photon produced
45. A tentative gamma-ray line from Dark Matter annihilation w/ Fermi Large Area Telescope 2)007 Weniger+12, JCAP Significance ~3-4σ
46. Energy (GeV) 60 80 100 120 140 160 180 200 220 -4 Energy (GeV) Events / 5.0 GeV 0 10 20 30 40 50 60 70 = 133.0 GeV γ P7_REP_CLEAN R3 2D E = 17.8 evts sig n σ = 3.3 local s = 276.2 evts bkg n = 2.76 bkg Γ (c) Energy (GeV) 60 80 100 120 140 160 180 200 220 ) σ Resid. ( -4 -2 0 2 4 Ackermann+13 sglobal ~1.6σ A tentative gamma-ray line from Dark Matter annihilation w/ Fermi Large Area Telescope
47. Busca por matéria escura no espaço: Fermi Large Area Telescope https://www.youtube.com/watch?v=WQZ0ElLgZ1c
48. Hooper & Linden 2011
49. Busca por matéria escura: experimentos em solo ars technica
50. Busca por matéria escura: experimentos em solo http://arstechnica.com/science/2014/07/the-quiet-search-for-dark-matter-deep-underground/2/
51. MOND a0 ⇥ 10 10 m s 2 cH0 c 1/2 Modify gravity at an acceleration scale a a0 a a0 a ⇥ gN ao a gN Hypothesized by Milgrom (1983) Slide courtesy: S. McGaugh Modified Newtonian Dynamics
52. The Radial Acceleration Relation in Rotationally Supported Galaxies Stacy S. McGaugh and Federico Lelli Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA James M. Schombert Department of Physics, University of Oregon, Eugene, OR 97403, USA (Dated: September 21, 2016) We report a correlation between the radial acceleration traced by rotation curves and that pre- dicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very di↵erent morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies. INTRODUCTION The missing mass problem in extragalactic systems is well established. The observed gravitational potential cannot be explained by the stars and gas. A classic ex- ample is that the rotation curves of disk galaxies become approximately flat (V ⇡ constant) when they should be falling in a Keplerian (V / R 1/2) fashion [1, 2]. The flatness of rotation curves is only the beginning of the story of the mass discrepancy in galaxies. For example, the baryonic mass of a galaxy (the sum of its stars and gas: Mbar = M? + Mg ) correlates with the amplitude of the flat rotation velocity Vf . This bary- onic Tully-Fisher relation [3–5] is a simple scaling rela- tion (Mbar / V 4 f ) with no apparent dependence on other properties like galaxy size [6, 7] or surface brightness [8, 9]. It has remarkably little intrinsic scatter [10–12]. This implies a strong connection between the baryons of the centripetal acceleration: gobs = V 2(R) R = @ tot @R , (1) where tot is the gravitational potential and V (R) is the full, resolved rotation curve. We do not consider pressure supported elliptical galaxies for which the derivation of the potential is more complex, but there are indications that they may obey a similar phenomenology [16–18]. Galaxy Sample We employ the new Spitzer Photometry and Accurate Rotation Curves (SPARC) database [19]. SPARC is a sample of 175 disk galaxies representing all rotationally supported morphological types. It includes near-infrared 17v1 [astro-ph.GA] 19 Sep 2016 S R D G V H T p o sp si o d o S. McGaugh et al. 16, PRL
53. EAGLE galaxy formation simulations: baryons and dark matter http://icc.dur.ac.uk/Eagle/index.php
54. http://icc.dur.ac.uk/Eagle/index.php EAGLE galaxy formation simulations: baryons and dark matter