Andi Kronawitter - Profile on Academia.edu (original) (raw)

Uploads

Papers by Andi Kronawitter

Research paper thumbnail of Dynamical Analysis of Elliptical Galaxy Halos

We describe a non-parametric method for determining both the anisotropy and mass profiles of elli... more We describe a non-parametric method for determining both the anisotropy and mass profiles of elliptical galaxies from velocity dispersions and velocity profile shapes along the line of sight. In this way, mass-to-light ratios out to 2-3 effective radii can be derived from stellar absorption line spectroscopy. We discuss two illustrative cases, NGC 1399 and NGC 6703. So far, all ellipticals which have been analysed show evidence for dark matter dominating in the outer parts. The circular velocity curves are nearly flat, as in spiral galaxies.

Research paper thumbnail of R.: The orbital structure and potential of NGC 1399

Accurate and radially extended stellar kinematic data reaching R = 97 ′ ′ from the center are pre... more Accurate and radially extended stellar kinematic data reaching R = 97 ′ ′ from the center are presented for the cD galaxy of Fornax, NGC 1399. The stellar rotation is small ( ≤ 30 km/s); the stellar velocity dispersion remains constant at 250-270 km/s. The deviations from Gaussian line of sight velocity distributions are small, at the percent level. We construct dynamical models of the galaxy, deprojecting its nearly round (E0-E1) surface brightness distribution, and determining the spherical distribution function that best fits (at the 4 percent level) the kinematic data on a grid of parametrized potentials. We find that the stellar orbital structure is moderately radial, with β = 0.3 ± 0.1 for R ≤ 60 ′ ′ , similar to results found for some normal giant ellipticals. The gravitational potential is dominated by the luminous component out to the last data point, with a mass-to-light ratio M/LB = 10 M⊙/L⊙, although the presence of a central black hole of M ≈ 5 × 10 8 M ⊙ is compatible ...

Research paper thumbnail of Dynamical analysis of elliptical galaxies

Dynamical analysis of elliptical galaxies

Evolution of Galaxies Dynamics of Galaxies and Galactic Nuclei, 1998

ABSTRACT We describe a non-parametric method for determining both the anisotropy and mass profile... more ABSTRACT We describe a non-parametric method for determining both the anisotropy and mass profiles of elliptical galaxies from velocity dispersions and velocity profile shapes along the line of sight. In this way, mass-to-light ratios out to 2-3 effective radii can be derived from stellar absorption line spectroscopy. We discuss two illustrative cases, NGC 1399 and NGC 6703. So far, all ellipticals which have been analysed show evidence for dark matter dominating in the outer parts. The circular velocity curves are nearly flat, as in spiral galaxies.

Research paper thumbnail of Orbital structure and mass distribution in elliptical galaxies

Astronomy and Astrophysics Supplement Series, 2000

We report on a homogeneous dynamical analysis of a sample of 21 round (17 E0/E1, 4 E2) elliptical... more We report on a homogeneous dynamical analysis of a sample of 21 round (17 E0/E1, 4 E2) elliptical galaxies. We present new kinematic data for eight of these galaxies and new photometry for one object. The remaining kinematic and photometric data and the required distance information are taken from the literature. The analysis uses non-parametric spherical models and takes into account line profile information as well as velocity dispersions. We present model fits to the kinematic data and the derived radial profiles of orbital anisotropy and B-band mass-to-light ratio, including confidence intervals. The circular velocity curves resulting from our model fits are all consistent with being flat outside R ≈ 0.3R e. Generally, the M/L ratio profiles show an outward increase, although models based on luminous matter are ruled out at 95% confidence only for three galaxies (NGC 2434, NGC 7507, NGC 7626). For NGC 1399, NGC 4472, NGC 4486, and NGC 4636, where X-ray observations are available, the mass profiles of the best fit models match the ones derived from the X-ray analysis. The best models for most galaxies are isotropic to slightly radially anisotropic, with typical β < ∼ 0.3, in a few cases β < ∼ 0.5 at R e /2. We discuss the generally small effects of flattening along the line-of-sight (the expected < c/a > = 0.79 for this sample of luminous ellipticals) and of small embedded disks. Our results suggest that elliptical galaxies have surprisingly uniform dynamical properties.

Research paper thumbnail of The Orbital Structure and Potential of NGC 1399

The Astronomical Journal, 2000

Accurate and radially extended stellar kinematic data reaching R = 97 from the center are present... more Accurate and radially extended stellar kinematic data reaching R = 97 from the center are presented for the cD galaxy of Fornax, NGC 1399. The stellar rotation is small (≤ 30 km/s); the stellar velocity dispersion remains constant at 250-270 km/s. The deviations from Gaussian line of sight velocity distributions are small, at the percent level. We construct dynamical models of the galaxy, deprojecting its nearly round (E0-E1) surface brightness distribution, and determining the spherical distribution function that best fits (at the 4 percent level) the kinematic data on a grid of parametrized potentials. We find that the stellar orbital structure is moderately radial, with β = 0.3 ± 0.1 for R ≤ 60 , similar to results found for some normal giant ellipticals. The gravitational potential is dominated by the luminous component out to the last data point, with a mass-to-light ratio M/L B = 10 M /L , although the presence of a central black hole of M ≈ 5 × 10 8 M is compatible with the data in the inner 5 arcsec. The infludence of the dark component is marginally detected starting from R ≈ 60 . Using the radial velocities of the globular clusters and planetary nebulae of the galaxy we constrain the potential more strongly, ruling out the self-consistent case and finding that the best fit solution agrees with X-ray determinations. The resulting total mass and mass-to-light ratio are M = 1.2 -2.5 × 10 12 M and M/L B = 22 -48 M /L inside R = 417 or 35 kpc for D=17.6 Mpc.

Research paper thumbnail of Preprint typeset using L ATEX style emulateapj v. 20/04/00 DYNAMICAL FAMILY PROPERTIES AND DARK HALO SCALING RELATIONS OF GIANT ELLIPTICAL GALAXIES

Based on a uniform dynamical analysis of the line-profile shapes of 21 mostly luminous, slowly ro... more Based on a uniform dynamical analysis of the line-profile shapes of 21 mostly luminous, slowly rotating, and nearly round elliptical galaxies, we have investigated the dynamical family relations and dark halo properties of ellipticals. Our results include: (i) The circular velocity curves (CVCs) of elliptical galaxies are flat to within ≃ 10 % for R ∼> 0.2Re. (ii) Most ellipticals are moderately radially anisotropic; their dynamical structure is surprisingly uniform. (iii) Elliptical galaxies follow a Tully-Fisher (TF) relation with marginally shallower slope than spiral galaxies, and vmax c ≃ 300 kms −1 for an L ∗ B galaxy. At given circular velocity, they are ∼ 1 mag fainter in B and ∼ 0.6 mag in R, and appear to have slightly lower baryonic mass than spirals, even for the maximum M/LB allowed by the kinematics. (iv) The luminosity dependence of M/LB indicated by the tilt of the Fundamental Plane (FP) is confirmed. The tilt of the FP is not caused by dynamical or photometric no...

Research paper thumbnail of Dynamical family properties and dark halo scaling relations of giant elliptical galaxies

The Astronomical …, 2001

Based on a uniform dynamical analysis of the line-proÐle shapes of 21 mostly luminous, slowly rot... more Based on a uniform dynamical analysis of the line-proÐle shapes of 21 mostly luminous, slowly rotating, and nearly round elliptical galaxies, we have investigated the dynamical family relations and dark halo properties of ellipticals. Our results include : (i) The circular velocity curves (CVCs) of elliptical galaxies are Ñat to within^10% for (ii) Most ellipticals are moderately radially anisotropic ;

Research paper thumbnail of Dynamical Analysis of Elliptical Galaxy Halos

We describe a non-parametric method for determining both the anisotropy and mass profiles of elli... more We describe a non-parametric method for determining both the anisotropy and mass profiles of elliptical galaxies from velocity dispersions and velocity profile shapes along the line of sight. In this way, mass-to-light ratios out to 2-3 effective radii can be derived from stellar absorption line spectroscopy. We discuss two illustrative cases, NGC 1399 and NGC 6703. So far, all ellipticals which have been analysed show evidence for dark matter dominating in the outer parts. The circular velocity curves are nearly flat, as in spiral galaxies.

Research paper thumbnail of R.: The orbital structure and potential of NGC 1399

Accurate and radially extended stellar kinematic data reaching R = 97 ′ ′ from the center are pre... more Accurate and radially extended stellar kinematic data reaching R = 97 ′ ′ from the center are presented for the cD galaxy of Fornax, NGC 1399. The stellar rotation is small ( ≤ 30 km/s); the stellar velocity dispersion remains constant at 250-270 km/s. The deviations from Gaussian line of sight velocity distributions are small, at the percent level. We construct dynamical models of the galaxy, deprojecting its nearly round (E0-E1) surface brightness distribution, and determining the spherical distribution function that best fits (at the 4 percent level) the kinematic data on a grid of parametrized potentials. We find that the stellar orbital structure is moderately radial, with β = 0.3 ± 0.1 for R ≤ 60 ′ ′ , similar to results found for some normal giant ellipticals. The gravitational potential is dominated by the luminous component out to the last data point, with a mass-to-light ratio M/LB = 10 M⊙/L⊙, although the presence of a central black hole of M ≈ 5 × 10 8 M ⊙ is compatible ...

Research paper thumbnail of Dynamical analysis of elliptical galaxies

Dynamical analysis of elliptical galaxies

Evolution of Galaxies Dynamics of Galaxies and Galactic Nuclei, 1998

ABSTRACT We describe a non-parametric method for determining both the anisotropy and mass profile... more ABSTRACT We describe a non-parametric method for determining both the anisotropy and mass profiles of elliptical galaxies from velocity dispersions and velocity profile shapes along the line of sight. In this way, mass-to-light ratios out to 2-3 effective radii can be derived from stellar absorption line spectroscopy. We discuss two illustrative cases, NGC 1399 and NGC 6703. So far, all ellipticals which have been analysed show evidence for dark matter dominating in the outer parts. The circular velocity curves are nearly flat, as in spiral galaxies.

Research paper thumbnail of Orbital structure and mass distribution in elliptical galaxies

Astronomy and Astrophysics Supplement Series, 2000

We report on a homogeneous dynamical analysis of a sample of 21 round (17 E0/E1, 4 E2) elliptical... more We report on a homogeneous dynamical analysis of a sample of 21 round (17 E0/E1, 4 E2) elliptical galaxies. We present new kinematic data for eight of these galaxies and new photometry for one object. The remaining kinematic and photometric data and the required distance information are taken from the literature. The analysis uses non-parametric spherical models and takes into account line profile information as well as velocity dispersions. We present model fits to the kinematic data and the derived radial profiles of orbital anisotropy and B-band mass-to-light ratio, including confidence intervals. The circular velocity curves resulting from our model fits are all consistent with being flat outside R ≈ 0.3R e. Generally, the M/L ratio profiles show an outward increase, although models based on luminous matter are ruled out at 95% confidence only for three galaxies (NGC 2434, NGC 7507, NGC 7626). For NGC 1399, NGC 4472, NGC 4486, and NGC 4636, where X-ray observations are available, the mass profiles of the best fit models match the ones derived from the X-ray analysis. The best models for most galaxies are isotropic to slightly radially anisotropic, with typical β < ∼ 0.3, in a few cases β < ∼ 0.5 at R e /2. We discuss the generally small effects of flattening along the line-of-sight (the expected < c/a > = 0.79 for this sample of luminous ellipticals) and of small embedded disks. Our results suggest that elliptical galaxies have surprisingly uniform dynamical properties.

Research paper thumbnail of The Orbital Structure and Potential of NGC 1399

The Astronomical Journal, 2000

Accurate and radially extended stellar kinematic data reaching R = 97 from the center are present... more Accurate and radially extended stellar kinematic data reaching R = 97 from the center are presented for the cD galaxy of Fornax, NGC 1399. The stellar rotation is small (≤ 30 km/s); the stellar velocity dispersion remains constant at 250-270 km/s. The deviations from Gaussian line of sight velocity distributions are small, at the percent level. We construct dynamical models of the galaxy, deprojecting its nearly round (E0-E1) surface brightness distribution, and determining the spherical distribution function that best fits (at the 4 percent level) the kinematic data on a grid of parametrized potentials. We find that the stellar orbital structure is moderately radial, with β = 0.3 ± 0.1 for R ≤ 60 , similar to results found for some normal giant ellipticals. The gravitational potential is dominated by the luminous component out to the last data point, with a mass-to-light ratio M/L B = 10 M /L , although the presence of a central black hole of M ≈ 5 × 10 8 M is compatible with the data in the inner 5 arcsec. The infludence of the dark component is marginally detected starting from R ≈ 60 . Using the radial velocities of the globular clusters and planetary nebulae of the galaxy we constrain the potential more strongly, ruling out the self-consistent case and finding that the best fit solution agrees with X-ray determinations. The resulting total mass and mass-to-light ratio are M = 1.2 -2.5 × 10 12 M and M/L B = 22 -48 M /L inside R = 417 or 35 kpc for D=17.6 Mpc.

Research paper thumbnail of Preprint typeset using L ATEX style emulateapj v. 20/04/00 DYNAMICAL FAMILY PROPERTIES AND DARK HALO SCALING RELATIONS OF GIANT ELLIPTICAL GALAXIES

Based on a uniform dynamical analysis of the line-profile shapes of 21 mostly luminous, slowly ro... more Based on a uniform dynamical analysis of the line-profile shapes of 21 mostly luminous, slowly rotating, and nearly round elliptical galaxies, we have investigated the dynamical family relations and dark halo properties of ellipticals. Our results include: (i) The circular velocity curves (CVCs) of elliptical galaxies are flat to within ≃ 10 % for R ∼> 0.2Re. (ii) Most ellipticals are moderately radially anisotropic; their dynamical structure is surprisingly uniform. (iii) Elliptical galaxies follow a Tully-Fisher (TF) relation with marginally shallower slope than spiral galaxies, and vmax c ≃ 300 kms −1 for an L ∗ B galaxy. At given circular velocity, they are ∼ 1 mag fainter in B and ∼ 0.6 mag in R, and appear to have slightly lower baryonic mass than spirals, even for the maximum M/LB allowed by the kinematics. (iv) The luminosity dependence of M/LB indicated by the tilt of the Fundamental Plane (FP) is confirmed. The tilt of the FP is not caused by dynamical or photometric no...

Research paper thumbnail of Dynamical family properties and dark halo scaling relations of giant elliptical galaxies

The Astronomical …, 2001

Based on a uniform dynamical analysis of the line-proÐle shapes of 21 mostly luminous, slowly rot... more Based on a uniform dynamical analysis of the line-proÐle shapes of 21 mostly luminous, slowly rotating, and nearly round elliptical galaxies, we have investigated the dynamical family relations and dark halo properties of ellipticals. Our results include : (i) The circular velocity curves (CVCs) of elliptical galaxies are Ñat to within^10% for (ii) Most ellipticals are moderately radially anisotropic ;