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Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem

-1. 100. log (r, M o /pc 3 ). V rot (km/s). Density profiles from long-slit spectra:. 60. -2. minimum disk. 1.0. 0.2. 0.6. r/r opt. 1. 0. log(r,kpc). spherical symmetry. Rotation curve. Density profile. Kristine Spekkens, Riccardo Giovanelli (Cornell).

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Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem

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  1. -1 100 log(r,Mo/pc3) Vrot (km/s) Density profiles from long-slit spectra: 60 -2 minimum disk 1.0 0.2 0.6 r/ropt 1 0 log(r,kpc) spherical symmetry Rotation curve Density profile Kristine Spekkens,Riccardo Giovanelli (Cornell) Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem 203rd AAS, Session 105: Wednesday, 7 January 2004

  2. r ~ r-am (small r) 40 Number of galaxies Cusp/core problem: CDM predictsaint~1 20 Direct inversion yieldsam~0.2 Is distribution ofam consistent with aint expected from CDM? 1 0.2 0.6 am Galaxy Sample and Analysis • Vrot < 130 km/s • Ha spectroscopy • No bulges, bars from • I-band photometry Select low mass systems from ~4800 object SFI++: 200 galaxies Invert RCs: Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  3. data data 0.2 0.2 sim., aint = 1 Fraction galaxies Fraction galaxies 0.1 0.1 0.6 0.6 0.2 0.2 1 1 am am Dwarf Population Simulations • Embed infinitely thin, uniform Ha disks inside NFW halos (aint = 1) • Observables random deviates of sample distributions • “Observe” simulated galaxies with single slit in same conditions as for sample • Analyze“observations” with same algorithms as for data Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  4. 0.5 data sim., aint = 1 am 0.3 40 80 120 Distance, Mpc 0.5 am 0.3 60 70 80 Inclination, deg Dwarf Population Simulations • Embed infinitely thin, uniform Ha disks inside NFW halos (aint = 1) • Observables random deviates of sample distributions • “Observe” simulated galaxies with single slit in same conditions as for sample • Analyze“observations” with same algorithms as for data Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  5. Varying aint Inner slopes from sample are: CONSISTENT withaint= 0.5 data 0.2 sim., aint = 0.5 Fraction galaxies 0.1 0.6 0.2 1 am Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  6. Varying aint Inner slopes from sample are: CONSISTENT withaint= 0.5 CONSISTENT with aint= 1 CONSISTENT with aint= 1.25 data 0.2 sim., aint = 1.25 Fraction galaxies 0.1 0.6 0.2 1 am Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  7. Varying aint Inner slopes from sample are: CONSISTENT withaint= 0.5 CONSISTENT with aint= 1 CONSISTENT with aint= 1.25 INCONSISTENT withaint= 1.5 data 0.2 sim., aint = 1.5 Fraction galaxies 0.1 0.6 0.2 1 am Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

  8. aint = 0.5 aint = 1 aint = 1.25 aint = 1.5 0.2 0.1 0.2 0.6 1.0 0.2 0.6 0.2 0.6 1.0 1.0 0.2 0.6 1.0 Is There Really a Cusp-Core Problem? (NFW) Fraction gals. am am am am Inner halo slopes derived from long-slit spectra are consistent with cuspy profiles predicted by CDM Recover distribution of amfrom cuspy aint with simulations of observing and data processing techniques Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies

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