29 research outputs found
The Origin of the Correlation Between the Spin Parameter and the Baryon Fraction of Galactic Disks
No full textThe Distribution of Mass in Spiral Galaxies.
No full textLittle is known about the content and distribution of dark matter in spiral galaxies. Mass modeling of any rotation curve can yield an alarming range of results - from entirely halo-dominated, centrally- concentrated dark distributions, to disk-dominated inner potentials with shallow, low density halos. To break this degeneracy, we propose to take advantage the the unique properties of the new SparsePak Integral Field Unit on WIYN. To do this successfully, a two-phased observational approach is required, as our pilot study has proven. First, we will obtain H(alpha) velocity fields for a sample of ~100 photometrically selected spiral galaxies to determine the regularity of the kinematics and the inclinations of the disks. These data will also be used to study disk ellipticities and kinematic asymmetries in the context of the scatter in the Tully-Fisher relation. Second, we will measure the stellar kinematics and velocity dispersions for a subsample of about 40 galaxies that were found to have kinematically well behaved disks and suitable inclinations. The stellar velocity dispersions provide a kinematic measurement of the stellar disk mass, thus breaking the degeneracy, making possible a measurement of the dark matter properties in spiral galaxies with unprecedented accuracy
The Distribution of Mass in Spiral Galaxies.
No full textLittle is known about the content and distribution of dark matter in spiral galaxies. Mass modeling of any rotation curve can yield an alarming range of results - from entirely halo-dominated, centrally- concentrated dark distributions, to disk-dominated inner potentials with shallow, low density halos. To break this degeneracy, we propose to take advantage the the unique properties of the new SparsePak Integral Field Unit on WIYN. To do this successfully, a two-phased observational approach is required, as our pilot study has proven. First, we will obtain H(alpha) velocity fields for a sample of ~100 photometrically selected spiral galaxies to determine the regularity of the kinematics and the inclinations of the disks. These data will also be used to study disk ellipticities and kinematic asymmetries in the context of the scatter in the Tully-Fisher relation. Second, we will measure the stellar kinematics and velocity dispersions for a subsample of about 40 galaxies that were found to have kinematically well behaved disks and suitable inclinations. The stellar velocity dispersions provide a kinematic measurement of the stellar disk mass, thus breaking the degeneracy, making possible a measurement of the dark matter properties in spiral galaxies with unprecedented accuracy
The Disk Mass Project: breaking the disk-halo degeneracy
No full textLittle is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here, we present our ongoing Disk Mass project, using two custom-built Integral Field Units, to measure the vertical velocity dispersion of stars in ~40 spiral galaxies. This will provide a kinematic measurement of the stellar disk mass required to break the degeneracy, enabling us to determine the dark matter properties in spiral galaxies with unprecedented accuracy. Here we present preliminary results for three galaxies with different central disk surface brightness levels
The Disk Mass Project
No full textLittle is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here, we present our ongoing Disk Mass project, using two custom-built Integral Field Units, to measure the vertical velocity dispersion of stars in ~40 spiral galaxies. This will provide a kinematic measurement of the stellar disk mass required to break the degeneracy, enabling us to determine the dark matter properties in spiral galaxies with unprecedented accuracy. Here we present preliminary results for three galaxies with different central disk surface brightness levels
The Disk Mass Project: breaking the disk-halo degeneracy
No full textLittle is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here, we present our ongoing Disk Mass project, using two custom-built Integral Field Units, to measure the vertical velocity dispersion of stars in ~40 spiral galaxies. This will provide a kinematic measurement of the stellar disk mass required to break the degeneracy, enabling us to determine the dark matter properties in spiral galaxies with unprecedented accuracy. Here we present preliminary results for three galaxies with different central disk surface brightness levels
The DiskMass Survey. II. Error Budget
No full textWe present a performance analysis of the DiskMass Survey. The survey uses
collisionless tracers in the form of disk stars to measure the surface-density of
spiral disks, to provide an absolute calibration of the stellar mass-to-light ratio
(), and to yield robust estimates of the dark-matter halo density profile in
the inner regions of galaxies. We find a disk inclination range of 25-35 is op-
timal for our measurements, consistent with our survey design to select nearly
face-on galaxies. Uncertainties in disk scale-heights are significant, but can be
estimated from radial scale-lengths to 25% now, and more precisely in the fu-
ture. We detail the spectroscopic analysis used to derive line-of-sight velocity
dispersions, precise at low surface-brightness, and accurate in the presence of
composite stellar populations.
The Stellar Velocity Dispersion in the Inner 1.3 Disk Scale Lengths of the Irregular Galaxy NGC 4449
No full textSparsePak: A Formatted Fiber Field Unit for The WIYN Telescope Bench Spectrograph. II. On-Sky Performance
No full textNRC publication: Ye
