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Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem Kristine Spekkens, Riccardo Giovanelli (Cornell) 203 rd AAS, Session 105: Wednesday,

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Presentation on theme: "Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem Kristine Spekkens, Riccardo Giovanelli (Cornell) 203 rd AAS, Session 105: Wednesday,"— Presentation transcript:

1 Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem Kristine Spekkens, Riccardo Giovanelli (Cornell) 203 rd AAS, Session 105: Wednesday, 7 January 2004 minimum disk spherical symmetry Density profiles from long-slit spectra: r/r opt V rot (km/s) Rotation curve log(r,kpc) log  M o /pc 3 ) Density profile

2 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Galaxy Sample and Analysis Select low mass systems from ~4800 object SFI++: V rot < 130 km/s H  spectroscopy No bulges, bars from I-band photometry 200 galaxies Invert RCs:  r -  m (small r) CDM predicts  int ~1 Direct inversion yields  m ~0.2 Cusp/core problem: Is distribution of  m consistent with  int  expected from CDM? Number of galaxies mm

3 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Dwarf Population Simulations 1. Embed infinitely thin, uniform H  disks inside NFW halos (  int = 1) 2. Observables random deviates of sample distributions 3. “Observe” simulated galaxies with single slit in same conditions as for sample 4. Analyze “observations” with same algorithms as for data data mm Fraction galaxies data mm Fraction galaxies sim.,  int = 1

4 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Dwarf Population Simulations data sim.,  int = 1 mm mm Distance, Mpc Inclination, deg 1. Embed infinitely thin, uniform H  disks inside NFW halos (  int = 1) 2. Observables random deviates of sample distributions 3. “Observe” simulated galaxies with single slit in same conditions as for sample 4. Analyze “observations” with same algorithms as for data

5 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Varying  int data mm Fraction galaxies sim.,  int = 0.5 Inner slopes from sample are: CONSISTENT with  int = 0.5

6 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Varying  int data mm Fraction galaxies sim.,  int = 1.25 Inner slopes from sample are: CONSISTENT with  int = 0.5 CONSISTENT with  int = 1 CONSISTENT with  int = 1.25

7 Kristine Spekkens – Inner Halo Shapes of Dwarf Galaxies Varying  int data mm Fraction galaxies sim.,  int = 1.5 Inner slopes from sample are: CONSISTENT with  int = 0.5 CONSISTENT with  int = 1 CONSISTENT with  int = 1.25 INCONSISTENT with  int = 1.5

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


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