1 / 43

Dec. 1-8, 2010

THE NATURE OF DARK MATTER IN GALAXIES. PAOLO SALUCCI. SISSA. Vistas in Axion Physics INT, 23-26 April,2012. Dec. 1-8, 2010. Outline of the Talk Dark Matter is main protagonist in the Universe The concept of Dark Matter in virialized objects

yachi
Download Presentation

Dec. 1-8, 2010

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. THE NATURE OF DARK MATTER IN GALAXIES PAOLO SALUCCI SISSA Vistas in Axion Physics INT, 23-26 April,2012 Dec. 1-8, 2010

  2. Outline of the Talk Dark Matter is main protagonist in the Universe The concept of Dark Matter in virialized objects Dark Matter in Spirals, Ellipticals, dSphs Phenomenology of the mass distribution in Galaxies. Implications The focus: Dark Matter in Galaxies

  3. spiral elliptical 3 major types of galaxies dwarfs

  4. The Realm of Galaxies The range of galaxies in magnitudes, types and central surface densities : 15 mag, 4 types, 16 mag arsec-2 Centralsurfacebrightness vs galaxymagnitude Dwarfs Spirals : stellar disk +bulge +HI disk Ellipticals & dwarfs E: stellar spheroid The distribution of luminous matter :

  5. What is Dark Matter ? In a galaxy, the radialprofileof the gravitatingmatter M(r) doesnot match thatof the luminouscomponentML(r). A MASSIVE DARK COMPONENT isthenintroducedto account for the disagreement: Itsprofile MH(r) mustobey: M(r), ML(r), dlog ML(r)/dlog r are observed The DM phenomenon can be investigated only if we accurately meausure the distribution of: LuminousmatterML(r). GravitatingmatterM(r)

  6. THEORY AND SIMULATIONS

  7. ΛCDM Dark Matter Density Profiles from N-body simulations The density of virialized DM halos of any mass is empirically described at all times by an Universal profile (Navarro+96, 97, NFW). More massive halos and those formed earlier have larger overdensities Today mean halo density inside Rvir = 100 ϱc Klypin, 2010

  8. Aquarius N-Body simulations, highest mass resolution to date. Density distribution: the Einasto Law indistinguishable by NFW density circular velocity Navarro et al +10 V=const

  9. SPIRALS

  10. Stellar Disks M33 disk very smooth, truncated at 4 scale-lengths NGC 300 exponential disk for at least 10 scale-lengths RD lenght scale of the disk Freeman, 1970 Bland-Hawthorn et al 2005 Ferguson et al 2003

  11. Wong & Blitz (2002) Gas surface densities H2 HI HI Flattishradialdistribution Deficiency in the centre Extendedto (8 – 40) RD H2 Follows the stellar disk Negligible

  12. Circularvelocitiesfromspectroscopy - Opticalemissionlines (H, Na) - Neutralhydrogen (HI)-carbonmonoxide (CO) Tracer angular spectral resolution resolution HI 7" … 30" 2 … 10 km s-1 CO 1.5" … 8" 2 … 10 km s-1 H, … 0.5" … 1.5" 10 … 30 km s-1 WSRT VLA IRAM ATCA

  13. VLT LBT KECK GTC

  14. ROTATION CURVES artistimpression artistimpression

  15. Symmetric circular rotation of a disk characterized by • Sky coordinates of the galaxy centre • Systemic velocity Vsys • Circular velocity V(R) • Inclination angle HIGH QUALITY ROTATION CURVE r receeding arm V(R/RD) trailingarm R/RD

  16. Early discovery from optical and HI RCs RC DO NOT follows the disk velocityprofile disk RC profilesofdifferent lenght scale and amplitude Rubinet al 1980 Mass discrepancy AT OUTER RADII

  17. mag Salucci+07 6 RD Rotation Curves Coadded from 3200 individual RCs TYPICAL INDIVIDUAL RCs SHOWN BY INCREASING LUMINOSITY Low lum high lum 6 RD

  18. The Conceptof the Universal Rotation Curve (URC) Every RC can be represented by: V(x,L) x=R/RD V/Vopt L R/RD ->Link to Movie 2 The URC out to 6 RD is derived directly from observations Extrapolation of URC out to virial radius by using V(Rvir )

  19. Rotation curve analysis From data to mass models observations = model • from I-band photometry • from HI observations • different choices for the DM halo density • Dark halos with central constant density (Burkert, Isothermal) • Dark halos with central cusps (NFW, Einasto) NFW ISO The mass model has 3 free parameters: disk mass halo central density Halo core radius (length-scale) Obtained by best fitting method Burkert

  20. halocentral density coreradius luminosity MASS MODELLING RESULTS MI= - 21 MI= - 23 MI= -18 highest luminosities lowest luminosities halo disk disk halo halo disk Allstructural DM and LM parameters are related withluminosity.g Smallergalaxies are denser and have a higherproportionof dark matter. fractionof DM

  21. The distributionof DM aroundspirals UsingindividualgalaxiesGentile+ 2004, de Blok+ 2008  Kuzio de Naray+ 2008, Oh+  2008, Spano+ 2008, Trachternach+ 2008, Donato+,2009 A detailedinvestigation: high quality data and modelindependentanalysis

  22. EXAMPLES DDO 47 Gentile et al 2005 NFW Burkert Oh et al , 2008 halo B halo V gas B disk B gas disk results from several samples e.g. THINGS - Non-circularmotions are small. - DM halospherical • ISO/Burkerthalosmuch more preferred over NFW Tri-axiality and non-circularmotionscannotexplain the CDM/NFW cusp/core discrepancy R

  23. The halo central surface density : constant in Spirals 3.0 2.5 2.0 1.5 1.0 URC Kormendy & Freeman (2004)

  24. SPIRALS: WHAT WE KNOW AN UNIVERSAL CURVE REPRESENTS ALL INDIVIDUAL RCs MORE PROPORTION OF DARK MATTER IN SMALLER SYSTEMS THE RADIUS IN WHICH THE DM SETS IN IS A FUNCTION OF LUMINOSITY DARK HALO DENSITY SHOWS A CENTRAL CORE OF SIZE 2 RD THE MASS PROFILE AT LARGER RADII IS COMPATIBLE WITH NFW

  25. ELLIPTICALS

  26. The Stellar Spheroid Surfacebrightnessofellipticalsfollows a Sersic Re the radiusenclosinghalfof the projected light. Bydeprojecting I(R) weobtain the luminosity density j(r): ESO 540-032 Sersicprofile B R

  27. Modelling Ellipticals Measure the light profile = stellar mass profile (M*/L)-1 Derive the total mass profile M(r) Dispersionvelocitiesofstars or ofPlanetaryNebulae X-raypropertiesof the emitting hot gas Weak and/or strong lensing data Disentangle M(r) intoits dark and the stellar components In ellipticalsgravityisbalancedbypressuregradients -> Jeans Equation anisotropy of the orbits grav. potential dispersion velocities

  28. Mass Profiles from X-ray Nigishita et al 2009 Temperature Density M/L profile CORED HALOS? NO DM HydrostaticEquilibrium

  29. Mass profilesfromweaklensing Lensingequationfor the observedtangentialshear e.g. Schneider,1996

  30. DM HALOS: BURKERT Donato et al 2009 NFW B SAME VALUES FOUND BY MASS MODELLING THE URC

  31. ELLIPTICALS: WHAT WE KNOW A LINK AMONG THE STRUCTURAL PROPERTIES OF STELLAR SPHEROID SMALL AMOUNT OF DM INSIDE RE MASS PROFILE COMPATIBLE WITH NFW AND BURKERT DARK MATTER DIRECTLY TRACED OUT TO RVIR

  32. dSphs

  33. Dwarf spheroidals: basic properties The smallestobjects in the Universe, benchmark fortheory dSph show largeMgrav/L Luminosities and sizes of Globular Clusters and dSph are different Gilmore et al 2009

  34. Kinematics of dSphs 2010: full radial coverage in each dSph: 1000 stars per galaxy Instruments: AF2/WYFFOS (WHT, La Palma); FLAMES (VLT); GMOS (Gemini); DEIMOS (Keck); MIKE (Magellan) STELLAR SPHEROID

  35. Mass profiles of dSphs Jeans’ models provide the most objective sample comparison Jeans equation relates kinematics, light and underlying mass distribution Make assumptions on the velocity anisotropy and then fit the dispersion profile PLUMMER PROFILE DENSITY PROFILE Results point to cored distributions Gilmore et al 2007

  36. Degeneracy between DM mass profile and velocity anisotropy Cored and cusped halos with orbit anisotropy fit dispersion profiles almost equally well Walker et al 2009 σ(R) km/s

  37. dSphscoredhalomodelhalocentraldensities correlate withcoreradius in the same way asSpirals and Ellipticals dSph S Donato et al 2009 E

  38. Global trend of dSph haloes Mateo et al 1998 Strigari et al 2008

  39. DSPH: WHAT WE KNOW PROVE THE EXISTENCE OF DM HALOS OF 1010 MSUN AND ρ0 =10-21 g/cm3 DOMINATED BY DARK MATTER AT ANY RADIUS MASS PROFILE CONSISTENT WITH THE EXTRAPOLATION OF THE URC

  40. GALAXY HALOS: AN UNIFIED VISION dSph Dw LSB S E

  41. WHAT WE KNOW? The distribution of DM in halosaroundgalaxies shows a striking and complexphenomenologycrucial to understand The nature of dark matter and the galaxy formation process Refined simulations should reproduce and the theory should explain: a shallow DM inner density distribution, a centralhalosurface density independent of halo mass and a series of relationshipsbetween the latter and the i) centralhalo density, ii) baryonic mass, iii) half-mass baryonicradius and iv) baryoniccentralsurface density Theory, phenomenology, simulations, experiments are all bound to play a role in the search for dark matter and its cosmological role. The mass discrepancy in galaxies is a complex function of radius, total baryonic mass, Hubble Type Unlikely all this masks a new law of Gravity but certainly it is beyond the present ΛCDM predictivepower

  42. This Presentation has been prepared by: Paolo Salucci, Christiane Frigerio Martins, Andrea Lapi with the scientific collaboration of: Elena Aprile, Mariangela Bernardi, Albert Bosma, Erwin de Blok, Ken Freeman, Refael Gavazzi, Gianfranco Gentile, Gerry Gilmore, Uli Klein, Gary Mamon, Claudia Maraston, Nicola Napolitano, Pierre Salati, Chiara Tonini, Mark Wilkinson, Irina Yegorova. with the support and encouragement of: J. Bailin, P. Biermann, A. Bressan, L. Danese, C. Frenk, S. Leach , M. Roos, V. Rubin. Thanks to everyone!

More Related