Marc Seigar - Academia.edu (original) (raw)

Papers by Marc Seigar

Research paper thumbnail of Determination of resonance locations in NGC 613 from morphological arguments

Monthly Notices of the Royal Astronomical Society

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Research paper thumbnail of Structure and dynamics of disk galaxies : proceedings of a conference held at The Winthrop Rockefeller Institute, Petit Jean Mountain, Arkansas, USA, 12-16 August 2013

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Research paper thumbnail of A Revised Mass Model For The Andromeda Galaxy

We present an updated mass model for M31 that utilizes a deep 2MASS K-band image of the Andromeda... more We present an updated mass model for M31 that utilizes a deep 2MASS K-band image of the Andromeda galaxy, a revised estimate of the stellar mass-to-light ratio (M/L), and observed rotation curve data from a variety of sources. We examine cases where the dark matter follows a pure NFW profile and where an initial NFW halo contracts adiabatically in response to the formation of the galaxy. We find that the rotation curve data are most consistent with an adiabatically contracted NFW halo with an initial concentration c_vir=12.0 and virial mass 8.7x10^{11} M_sun. Models without adiabatic contraction are disfavored at high significance and specifically have difficulty reproducing the decline in rotation velocity at r>15 kpc. Our best-fit M31 virial mass is a factor of ~2 smaller than the most recent estimate from rotation curve fitting by Klypin et al. (2002). The difference is driven by our updated baryonic mass model. The best-fit mass is consistent with published estimates from Andromeda Stream kinematics, satellite galaxy radial velocities, and planetary nebulae studies. Finally, using the known linear correlation between rotation curve shear and spiral arm pitch angle, we show that the stellar spiral arm pitch angle of M31 (which cannot be deduced from imaging data due to the galaxy's inclination) is P=24.7+/-4.4 degrees.

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Research paper thumbnail of Constraining Dark Matter Halo Profiles and Galaxy Formation Models Using Spiral Arm Morpholohy. I. Method Outline

The Astrophysical Journal, Jul 10, 2006

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Research paper thumbnail of A revised Lambda CDM mass model for the Andromeda Galaxy

Mon Notic Roy Astron Soc, 2008

We present an updated mass model for M31 that makes use of a Spitzer 3.6-mum image, a mass-to-lig... more We present an updated mass model for M31 that makes use of a Spitzer 3.6-mum image, a mass-to-light ratio gradient based on the galaxy's B - R colour profile, and observed rotation curve data from a variety of sources. We examine cases where the dark matter follows a pure Navarro, Frenk & White (NFW) profile and where an initial NFW halo contracts adiabatically in response to the formation of the galaxy. We find that both of these scenarios can produce a reasonable fit to the observed rotation curve data. However, a pure NFW model requires a concentration cvir = 51 which is well outside the range predicted in Lambdacold dark matter cosmology and is therefore disfavoured. An adiabatically contracted NFW halo favours an initial concentration cvir = 20 and virial mass 8.2 × 1011Msolar, and this is in line with the cosmological expectations for a galaxy of the size of M31. The best-fitting mass is consistent with published estimates from Andromeda Stream kinematics, satellite galaxy radial velocities and planetary nebulae studies. Finally, using the known linear correlation between rotation curve shear and spiral arm pitch angle, we show that the stellar spiral arm pitch angle of M31 (which cannot be deduced from imaging data due to the galaxy's inclination) is P=24.7° ± 4.4°.

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Research paper thumbnail of Determination of Resonance Locations in the Barred Spiral Galaxy, NGC 613

Bulletin of the American Astronomical Society, 2011

ABSTRACT

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Research paper thumbnail of The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

ISRN Astronomy and Astrophysics, 2011

We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of... more We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of and a virial mass of . We go on to use the NFW concentration of M33, along with the values derived for other galaxies (as found in the literature), to show that correlates with both spiral arm pitch angle and supermassive black hole mass.

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Research paper thumbnail of The structure of spiral galaxies - I. Near-infrared properties of bulges, disks and bars

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Research paper thumbnail of Spiral Galaxies with HST - Near Infrared Properties of Bulges

We have obtained HST_NICMOS images for 72 nearby spiral galaxy bulges in the H-band. These data s... more We have obtained HST_NICMOS images for 72 nearby spiral galaxy bulges in the H-band. These data show that galaxies with regular bulges have steeper nuclear cusps than galaxies with irregular bulges. We also show that galaxies with regular bulges fall on the same part of the (<\gamma>, magnitude)-diagram as elliptical galaxies. This implies that early-type spiral galaxy bulges have a formation process in common with ellipticals.

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Research paper thumbnail of The Arkansas Galaxy Evolution Survey (AGES): Supermassive Black Holes in the Universe

The Arkansas Galaxy Evolution Survey is conducting a census of supermassive black hole (SMBH) mas... more The Arkansas Galaxy Evolution Survey is conducting a census of supermassive black hole (SMBH) masses over cosmological epochs, as a contribution to understanding the role played by these objects in the evolution of galactic structure. Presently there are three main projects within the collaboration. The first aims to make use of a relation, newly discovered by the collaboration, between SMBH mass and spiral arm pitch angle in disc galaxies, as a tool to estimate the masses of SMBHs in quiescent galaxies out to redshifts of z=1. The second aims to search for binary SMBHs in ultra luminous infrared galaxies by looking for evidence of binarity in X-ray images of their galactic nuclei. The third will look for evidence of SMBH mass evolution over the peak of quasar luminosity evolution from z=2 to z=4. We briefly describe the three projects, and discuss how they will contribute to a deeper understanding of the role of SMBHs in the evolution of galactic structure.

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Research paper thumbnail of Determination of Resonance Locations in Spiral Galaxies using Multi-band Photometry

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Research paper thumbnail of The nature of near-infrared emission from spiral galaxies

Astronomy and Astrophysics

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Research paper thumbnail of The Nuclei of Nearby Giant Elliptical Galaxies

ABSTRACT

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Research paper thumbnail of The co-evolution of spiral structure and mass distribution in disk galaxies

ABSTRACT

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Research paper thumbnail of Mass Distribution in Spiral Galaxies from Characteristics of Spiral Structure: Constraints on Galaxy formation models

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Research paper thumbnail of Mass distribution of spiral galaxies from characteristics of spiral structure: Constraints on galaxy formation models

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Research paper thumbnail of A Revised LCDM Mass Model For The Andromeda Galaxy

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Research paper thumbnail of The Arkansas Galaxy Evolution Survey (AGES): The Evolution of the Supermassive Black Hole Mass Function in Spiral Galaxies

ABSTRACT

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Research paper thumbnail of Cold dark matter, hot dark matter, and their alternatives

Dark Matter in the Universe, 2014

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Research paper thumbnail of The Carnegie-Irvine Galaxy Survey (CGS). I. (Ho+, 2011)

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Research paper thumbnail of Determination of resonance locations in NGC 613 from morphological arguments

Monthly Notices of the Royal Astronomical Society

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Research paper thumbnail of Structure and dynamics of disk galaxies : proceedings of a conference held at The Winthrop Rockefeller Institute, Petit Jean Mountain, Arkansas, USA, 12-16 August 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Revised Mass Model For The Andromeda Galaxy

We present an updated mass model for M31 that utilizes a deep 2MASS K-band image of the Andromeda... more We present an updated mass model for M31 that utilizes a deep 2MASS K-band image of the Andromeda galaxy, a revised estimate of the stellar mass-to-light ratio (M/L), and observed rotation curve data from a variety of sources. We examine cases where the dark matter follows a pure NFW profile and where an initial NFW halo contracts adiabatically in response to the formation of the galaxy. We find that the rotation curve data are most consistent with an adiabatically contracted NFW halo with an initial concentration c_vir=12.0 and virial mass 8.7x10^{11} M_sun. Models without adiabatic contraction are disfavored at high significance and specifically have difficulty reproducing the decline in rotation velocity at r>15 kpc. Our best-fit M31 virial mass is a factor of ~2 smaller than the most recent estimate from rotation curve fitting by Klypin et al. (2002). The difference is driven by our updated baryonic mass model. The best-fit mass is consistent with published estimates from Andromeda Stream kinematics, satellite galaxy radial velocities, and planetary nebulae studies. Finally, using the known linear correlation between rotation curve shear and spiral arm pitch angle, we show that the stellar spiral arm pitch angle of M31 (which cannot be deduced from imaging data due to the galaxy's inclination) is P=24.7+/-4.4 degrees.

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Research paper thumbnail of Constraining Dark Matter Halo Profiles and Galaxy Formation Models Using Spiral Arm Morpholohy. I. Method Outline

The Astrophysical Journal, Jul 10, 2006

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Research paper thumbnail of A revised Lambda CDM mass model for the Andromeda Galaxy

Mon Notic Roy Astron Soc, 2008

We present an updated mass model for M31 that makes use of a Spitzer 3.6-mum image, a mass-to-lig... more We present an updated mass model for M31 that makes use of a Spitzer 3.6-mum image, a mass-to-light ratio gradient based on the galaxy's B - R colour profile, and observed rotation curve data from a variety of sources. We examine cases where the dark matter follows a pure Navarro, Frenk & White (NFW) profile and where an initial NFW halo contracts adiabatically in response to the formation of the galaxy. We find that both of these scenarios can produce a reasonable fit to the observed rotation curve data. However, a pure NFW model requires a concentration cvir = 51 which is well outside the range predicted in Lambdacold dark matter cosmology and is therefore disfavoured. An adiabatically contracted NFW halo favours an initial concentration cvir = 20 and virial mass 8.2 × 1011Msolar, and this is in line with the cosmological expectations for a galaxy of the size of M31. The best-fitting mass is consistent with published estimates from Andromeda Stream kinematics, satellite galaxy radial velocities and planetary nebulae studies. Finally, using the known linear correlation between rotation curve shear and spiral arm pitch angle, we show that the stellar spiral arm pitch angle of M31 (which cannot be deduced from imaging data due to the galaxy's inclination) is P=24.7° ± 4.4°.

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Research paper thumbnail of Determination of Resonance Locations in the Barred Spiral Galaxy, NGC 613

Bulletin of the American Astronomical Society, 2011

ABSTRACT

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Research paper thumbnail of The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

ISRN Astronomy and Astrophysics, 2011

We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of... more We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of and a virial mass of . We go on to use the NFW concentration of M33, along with the values derived for other galaxies (as found in the literature), to show that correlates with both spiral arm pitch angle and supermassive black hole mass.

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Research paper thumbnail of The structure of spiral galaxies - I. Near-infrared properties of bulges, disks and bars

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Spiral Galaxies with HST - Near Infrared Properties of Bulges

We have obtained HST_NICMOS images for 72 nearby spiral galaxy bulges in the H-band. These data s... more We have obtained HST_NICMOS images for 72 nearby spiral galaxy bulges in the H-band. These data show that galaxies with regular bulges have steeper nuclear cusps than galaxies with irregular bulges. We also show that galaxies with regular bulges fall on the same part of the (<\gamma>, magnitude)-diagram as elliptical galaxies. This implies that early-type spiral galaxy bulges have a formation process in common with ellipticals.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Arkansas Galaxy Evolution Survey (AGES): Supermassive Black Holes in the Universe

The Arkansas Galaxy Evolution Survey is conducting a census of supermassive black hole (SMBH) mas... more The Arkansas Galaxy Evolution Survey is conducting a census of supermassive black hole (SMBH) masses over cosmological epochs, as a contribution to understanding the role played by these objects in the evolution of galactic structure. Presently there are three main projects within the collaboration. The first aims to make use of a relation, newly discovered by the collaboration, between SMBH mass and spiral arm pitch angle in disc galaxies, as a tool to estimate the masses of SMBHs in quiescent galaxies out to redshifts of z=1. The second aims to search for binary SMBHs in ultra luminous infrared galaxies by looking for evidence of binarity in X-ray images of their galactic nuclei. The third will look for evidence of SMBH mass evolution over the peak of quasar luminosity evolution from z=2 to z=4. We briefly describe the three projects, and discuss how they will contribute to a deeper understanding of the role of SMBHs in the evolution of galactic structure.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Determination of Resonance Locations in Spiral Galaxies using Multi-band Photometry

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The nature of near-infrared emission from spiral galaxies

Astronomy and Astrophysics

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Research paper thumbnail of The Nuclei of Nearby Giant Elliptical Galaxies

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The co-evolution of spiral structure and mass distribution in disk galaxies

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Mass Distribution in Spiral Galaxies from Characteristics of Spiral Structure: Constraints on Galaxy formation models

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Mass distribution of spiral galaxies from characteristics of spiral structure: Constraints on galaxy formation models

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Revised LCDM Mass Model For The Andromeda Galaxy

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Arkansas Galaxy Evolution Survey (AGES): The Evolution of the Supermassive Black Hole Mass Function in Spiral Galaxies

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Cold dark matter, hot dark matter, and their alternatives

Dark Matter in the Universe, 2014

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Research paper thumbnail of The Carnegie-Irvine Galaxy Survey (CGS). I. (Ho+, 2011)

Bookmarks Related papers MentionsView impact