Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
- Publication Year
- Publication
Articles 61 - 90 of 90
Full-Text Articles in Astrophysics and Astronomy
Quantified H I Morphology – Iv. The Merger Fraction And Rate In Whisp., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Quantified H I Morphology – Iv. The Merger Fraction And Rate In Whisp., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Faculty and Staff Scholarship
The morphology of the atomic hydrogen (H I) disc of a spiral galaxy is the first component to be disturbed by a gravitational interaction such as a merger between two galaxies. We use a simple parametrization of the morphology of H I column density maps of the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies (WHISP) project to select those galaxies that are likely undergoing a significant interaction. Merging galaxies occupy a particular part of parameter space defined by Asymmetry (A), the relative contribution of the 20 per cent brightest pixels to the second-order moment of the column …
The Vlt Lbg Redshift Survey I: Clustering And Dynamics Of ≈ 1000 Galaxies At Z ≈ 3⋆, R. M. Bielby, T. Shanks, P. M. Weilbacher, L. Infante, N. H.M. Crighton, C. Bornancini, N. Bouché, P. Héraudeau, D. G. Lambas, James D. Lowenthal, D. Minniti, N. Padilla, P. Petitjean, T. Theuns
The Vlt Lbg Redshift Survey I: Clustering And Dynamics Of ≈ 1000 Galaxies At Z ≈ 3⋆, R. M. Bielby, T. Shanks, P. M. Weilbacher, L. Infante, N. H.M. Crighton, C. Bornancini, N. Bouché, P. Héraudeau, D. G. Lambas, James D. Lowenthal, D. Minniti, N. Padilla, P. Petitjean, T. Theuns
Astronomy: Faculty Publications
We present the initial imaging and spectroscopic data acquired as part of the Very Large Telescope (VLT) VIMOS Lyman-break galaxy Survey. UBR (or UBVI) imaging covers five ≈36 × 36 arcmin fields centred on bright z > 3 quasi-stellar objects (QSOs), allowing ≈210002 < z < 3.5 galaxy candidates to be selected using the Lyman-break technique. We performed spectroscopic follow-up using VLT VIMOS, measuring redshifts for 1020 z > 2 Lyman-break galaxies and 10 z > 2 QSOs from a total of 19 VIMOS pointings. From the galaxy spectra, we observe a 625 ± 510kms velocity offset between the interstellar absorption and Lyman α emission-line redshifts, consistent with previous results. Using the photometric and spectroscopic catalogues, we have analysed the galaxy clustering at z≈ 3. The angular correlation …
Herschel Observations Of The Centaurus Oluster - The Dynamics Of Cold Gas In A Cool Core, R. Mittal, C. P. O'Dea, Gary J. Ferland, J. B. R. Oonk, A. C. Edge, R. E. A. Canning, H. Russell, S. A. Baum, H. Böhringer, F. Combes, M. Donahue, A. C. Fabian, N. A. Hatch, A. Hoffer, R. Johnstone, B. R. Mcnamara, P. Salomé, G. Tremblay
Herschel Observations Of The Centaurus Oluster - The Dynamics Of Cold Gas In A Cool Core, R. Mittal, C. P. O'Dea, Gary J. Ferland, J. B. R. Oonk, A. C. Edge, R. E. A. Canning, H. Russell, S. A. Baum, H. Böhringer, F. Combes, M. Donahue, A. C. Fabian, N. A. Hatch, A. Hoffer, R. Johnstone, B. R. Mcnamara, P. Salomé, G. Tremblay
Physics and Astronomy Faculty Publications
Brightest cluster galaxies (BCGs) in the cores of galaxy clusters have distinctly different properties from other low-redshift massive ellipticals. The majority of the BCGs in cool-core clusters show signs of active star formation. We present observations of NGC 4696, the BCG of the Centaurus galaxy cluster, at far-infrared (FIR) wavelengths with theHerschel space telescope. Using the PACS spectrometer, we detect the two strongest coolants of the interstellar medium, [C II] at 157.74 μm and [O I] at 63.18 μm, and in addition [N II] at 121.90 μm. The [C II] emission is extended over a region of 7 kpc …
Testing Modified Newtonian Dynamics With Rotation Curves Of Dwarf And Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Testing Modified Newtonian Dynamics With Rotation Curves Of Dwarf And Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
Dwarf and low surface brightness (LSB) galaxies are ideal objects to test modified Newtonian dynamics (MOND), because in most of these galaxies the accelerations fall below the threshold where MOND supposedly applies. We have selected from the literature a sample of 27 dwarf and LSB galaxies. MOND is successful in explaining the general shape of the observed rotation curves for roughly three quarters of the galaxies in the sample presented here. However, for the remaining quarter, MOND does not adequately explain the observed rotation curves. Considering the uncertainties in distances and inclinations for the galaxies in our sample, a small …
Comparing The Dark Matter Halos Of Spiral, Low Surface Brightness, And Dwarf Spheroidal Galaxies, Stacy S. Mcgaugh
Comparing The Dark Matter Halos Of Spiral, Low Surface Brightness, And Dwarf Spheroidal Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We consider dark masses measured from kinematic tracers at discrete radii in galaxies for which baryonic contributions to overall potentials are either subtracted or negligible. Recent work indicates that rotation curves due to dark matter (DM) halos at intermediate radii in spiral galaxies are remarkably similar, with a mean rotation curve given by log10(V c,DM/(km s-1)) = 1.47+0.15-0.19 + 0.5log10(r/kpc). Independent studies show that while estimates of the dark mass of a given dwarf spheroidal (dSph) galaxy are robust only near the half-light radius, data from the Milky Way's (MW's) dSph satellites are consistent with a narrow range of mass …
Kinematic And Photometric Evidence For A Bar In Ngc 2683, Stacy S. Mcgaugh
Kinematic And Photometric Evidence For A Bar In Ngc 2683, Stacy S. Mcgaugh
Faculty Scholarship
We present optical long-slit and SparsePak Integral Field Unit emission line spectroscopy along with optical broadband and near-IR images of the edge-on spiral galaxy NGC 2683. We find a multi-valued, figure-of-eight velocity structure in the inner 45″ of the long-slit spectrum and twisted isovelocity contours in the velocity field. We also find, regardless of wavelength, that the galaxy isophotes are boxy. We argue that taken together, these kinematic and photometric features are evidence for the presence of a bar in NGC 2683. We use our data to constrain the orientation and strength of the bar.
The Baryonic Tully-Fisher Relation And Its Implication For Dark Matter Halos, Stacy S. Mcgaugh
The Baryonic Tully-Fisher Relation And Its Implication For Dark Matter Halos, Stacy S. Mcgaugh
Faculty Scholarship
Context. The baryonic Tully-Fisher relation (BTF) is a fundamental relation between baryonic mass and maximum rotation velocity. It can be used to estimate distances, as well as to constrain the properties of dark matter and its relation with the visible matter.Aims. In this paper, we explore if extremely low-mass dwarf galaxies follow the same BTF relation as high-mass galaxies. We quantify the scatter in the BTF relation and use this to constrain the allowed elongations of dark matter halo potentials.Methods. We obtained H I synthesis data of 11 dwarf galaxies and derive several independent estimates for the maximum rotation velocity.Results. …
The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof De Jong, Benne W. Holwerda
The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof De Jong, Benne W. Holwerda
Faculty and Staff Scholarship
We analyse warps in the nearby edge-on spiral galaxies observed in the Spitzer/Infrared Array Camera (IRAC )4.5-μm band. In our sample of 24 galaxies, we find evidence of warp in 14 galaxies. We estimate the observed onset radii for the warps in a subsample of 10 galaxies. The dark matter distribution in each of these galaxies are calculated using the mass distribution derived from the observed light distribution and the observed rotation curves. The theoretical predictions of the onset radii for the warps are then derived by applying a self-consistent linear response theory to the obtained mass models for six …
Constraining The Nfw Potential With Observations And Modeling Of Low Surface Brightness Galaxy Velocity Fields, Stacy S. Mcgaugh, J. Christopher Mihos
Constraining The Nfw Potential With Observations And Modeling Of Low Surface Brightness Galaxy Velocity Fields, Stacy S. Mcgaugh, J. Christopher Mihos
Faculty Scholarship
We model the Navarro-Frenk-White (NFW) potential to determine if, and under what conditions, the NFW halo appears consistent with the observed velocity fields of low surface brightness (LSB) galaxies. We present mock DensePak Integral Field Unit (IFU) velocity fields and rotation curves of axisymmetric and nonaxisymmetric potentials that are well matched to the spatial resolution and velocity range of our sample galaxies. We find that the DensePak IFU can accurately reconstruct the velocity field produced by an axisymmetric NFW potential and that a tilted-ring fitting program can successfully recover the corresponding NFW rotation curve. We also find that nonaxisymmetric potentials …
Erasing Dark Matter Cusps In Cosmological Galactic Halos With Baryons, Emilio Romano-Diaz, Isaac Shlosman, Yehuda Hoffman, Clayton Heller
Erasing Dark Matter Cusps In Cosmological Galactic Halos With Baryons, Emilio Romano-Diaz, Isaac Shlosman, Yehuda Hoffman, Clayton Heller
Physics & Astronomy: Faculty Publications
We study the central dark matter (DM) cusp evolution in cosmologically grown galactic halos. Numerical models with and without baryons (baryons+DM, hereafter BDM model, and pure DM, PDM model, respectively) are advanced from identical initial conditions, obtained using the Constrained Realization method. The DM cusp properties are contrasted by a direct comparison of pure DM and baryonic models. We find a divergent evolution between the PDM and BDM models within the inner few × 10 kpc region. The PDM model forms an R−1 cusp as expected, while the DM in the BDM model forms a larger isothermal cusp R …
Vimos-Vlt Integral Field Kinematics Of The Giant Low Surface Brightness Galaxy Eso 323-G064, Stacy S. Mcgaugh
Vimos-Vlt Integral Field Kinematics Of The Giant Low Surface Brightness Galaxy Eso 323-G064, Stacy S. Mcgaugh
Faculty Scholarship
Aims. We have studied the bulge and the disk kinematics of the giant low surface brightness galaxy ESO 323-G064 in order to investigate its dynamical properties and the radial mass profile of the dark matter (DM) halo. Methods. We observed the galaxy with integral field spectroscopy (VLT/VIMOS, in IFU configuration), measured the positions of the ionized gas by fitting Gaussian functions to the [O III] λλ4959,5007 and Hβ emission lines, and fit stellar templates to the galaxy spectra to determine velocity and velocity dispersions. We modeled the stellar kinematics in the bulge with spherical Isotropie Jeans models and explored the …
Milky Way Mass Models And Mond, Stacy S. Mcgaugh
Milky Way Mass Models And Mond, Stacy S. Mcgaugh
Faculty Scholarship
Using the Tuorla-Heidelberg model for the mass distribution of the Milky Way, I determine the rotation curve predicted by MOND (modified Newtonian dynamics). The result is in good agreement with the observed terminal velocities interior to the solar radius and with estimates of the Galaxy's rotation curve exterior thereto. There are no fit parameters: given the mass distribution, MOND provides a good match to the rotation curve. The Tuorla-Heidelberg model does allow for a variety of exponential scale lengths; MOND prefers short scale lengths in the range 2.0 kpc ≲ Rd ≲ 2.5 kpc. The favored value of Rd depends …
Mass Models For Low Surface Brightness Galaxies With High-Resolution Optical Velocity Fields, Stacy S. Mcgaugh
Mass Models For Low Surface Brightness Galaxies With High-Resolution Optical Velocity Fields, Stacy S. Mcgaugh
Faculty Scholarship
We present high-resolution optical velocity fields from DensePak integral field spectroscopy, along with derived rotation curves, for a sample of low surface brightness galaxies. In the limit of no baryons, we fit the NFW and pseudoisothermal halo models to the data and find the rotation curve shapes and halo central densities to be better described by the isothermal halo. For those galaxies with photometry, we present halo fits for three assumptions of the stellar mass-to-light ratio, Υ*. We find that the velocity contribution from the baryons is significant enough in the maximum disk case that maximum disk and the NFW …
The Rotation Velocity Attributable To Dark Matter At Intermediate Radii In Disk Galaxies, Stacy S. Mcgaugh
The Rotation Velocity Attributable To Dark Matter At Intermediate Radii In Disk Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We examine the amplitude of the rotation velocity that can be attributed to the dark matter halos of disk galaxies, focusing on well-measured intermediate radii. The data for 60 galaxies spanning a large range of mass and Hubble types, taken together, are consistent with a dark halo velocity log Vh = C + B log R with C = 1.47-0.19+0.15 and B ≈1/2 over the range of 1 < R < 74 kpc. The range in C stems from different choices of the stellar mass estimator, from minimum to maximum disk. For all plausible choices of stellar mass, the implied densities of the dark halos are lower than expected from structure formation simulations in ACDM, which anticipate C > 1.6. This problem is not specific to a particular type of galaxy or to the innermost region of the halo (cusp or core); the velocity attributable to dark matter is too low …
High-Resolution Optical Velocity Fields Of 11 Low Surface Brightness Galaxies, Stacy S. Mcgaugh
High-Resolution Optical Velocity Fields Of 11 Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We present high-resolution two-dimensional velocity fields from integral field spectroscopy, along with derived rotation curves for 11 low surface brightness galaxies. We fit NFW and pseudoisothermal halo models to the new data combined with previous long-slit and H I data. In most cases, we find the pseudoisothermal halo to better represent the data than the NFW halo, as the NFW concentrations are often lower than expected for a ACDM cosmology. We also compare our results to previous studies and find that including the new two-dimensional optical data does not significantly alter the halo parameters but does decrease the uncertainties by …
Evolution Of Stellar Bars In Live Axisymmetric Halos: Recurrent Buckling And Secular Growth, Inma Martinez-Valpuesta, Isaac Shlosman, Clayton Heller
Evolution Of Stellar Bars In Live Axisymmetric Halos: Recurrent Buckling And Secular Growth, Inma Martinez-Valpuesta, Isaac Shlosman, Clayton Heller
Physics & Astronomy: Faculty Publications
Evolution of stellar bars in disk galaxies is accompanied by dynamical instabilities and secular changes. Following the vertical buckling instability, the bars are known to weaken dramatically and develop a pronounced boxy/ peanut shape when observed edge-on. Using high-resolution N-body simulations of stellar disks embedded in live axisymmetric dark matter halos, we have investigated the long-term changes in the bar morphology, specifically the evolution of the bar size, its vertical structure, and the exchange of angular momentum. We find that following the initial buckling, the bar resumes its growth from deep inside the corotation radius and follows the ultraharmonic resonance …
The Compression Of Dark Matter Halos By Baryonic Infall, Stacy S. Mcgaugh
The Compression Of Dark Matter Halos By Baryonic Infall, Stacy S. Mcgaugh
Faculty Scholarship
The initial radial density profiles of dark matter halos are laid down by gravitational collapse in hierarchical structure formation scenarios and are subject to further compression as baryons cool and settle to the halo centers. Here we describe an explicit implementation of the algorithm, originally developed by Young, to calculate changes to the density profile as the result of adiabatic infall in a spherical halo model. Halos with random motion are more resistant to compression than are those in which random motions are neglected, which is a key weakness of the simple method widely employed. Young's algorithm results in density …
The Baryonic Tully-Fisher Relation Of Galaxies With Extended Rotation Curves And The Stellar Mass Of Rotating Galaxies, Stacy S. Mcgaugh
The Baryonic Tully-Fisher Relation Of Galaxies With Extended Rotation Curves And The Stellar Mass Of Rotating Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
I investigate the baryonic Tully-Fisher relation for a sample of galaxies with extended 21 cm rotation curves spanning the range 20 km s-1 ≲ Vf ≤ 300 km s-1. A variety of scalings of the stellar mass-to-light ratio Υ* are considered. For each prescription for Υ*, I give fits of the form Md = AVfx. Presumably, the prescription that comes closest to the correct value will minimize the scatter in the relation. The fit with minimum scatter has A = 50 M⊙ km-4 s4 and x = 4. This relation holds over five decades in mass. Galaxy color, stellar fraction, …
Regularized Orbit Models Unveiling The Stellar Structure And Dark Matter Halo Of The Coma Elliptical Ngc 4807, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner
Regularized Orbit Models Unveiling The Stellar Structure And Dark Matter Halo Of The Coma Elliptical Ngc 4807, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner
Dartmouth Scholarship
This is the second in a series of papers dedicated to unveiling the mass structure and orbital content of a sample of flattened early-type galaxies in the Coma cluster. The ability of our orbit libraries to reconstruct internal stellar motions and the mass composition of a typical elliptical in the sample is investigated by means of Monte Carlo simulations of isotropic rotator models. The simulations allow a determination of the optimal amount of regularization needed in the orbit superpositions. It is shown that under realistic observational conditions and with the appropriate regularization, internal velocity moments can be reconstructed to an …
The Mass Discrepancy-Acceleration Relation: Disk Mass And The Dark Matter Distribution, Stacy S. Mcgaugh
The Mass Discrepancy-Acceleration Relation: Disk Mass And The Dark Matter Distribution, Stacy S. Mcgaugh
Faculty Scholarship
The mass discrepancy in disk galaxies is shown to be well correlated with acceleration, increasing systematically with decreasing acceleration below a critical scale a0 ≈ 3700 km2 s-2 kpc -1 = 1.2 × 10-10 m s-2. For each galaxy, there is an optimal choice of stellar mass-to-light ratio that minimizes the scatter in this mass discrepancy-acceleration relation. The same mass-to-light ratios also minimize the scatter in the baryonic Tully-Fisher relation and are in excellent agreement with the expectations of stellar population synthesis. Once the disk mass is determined in this fashion, the dark matter distribution is specified. The circular velocity …
High-Resolution Rotation Curves Of Low Surface Brightness Galaxies. I. Data, Stacy S. Mcgaugh
High-Resolution Rotation Curves Of Low Surface Brightness Galaxies. I. Data, Stacy S. Mcgaugh
Faculty Scholarship
We present long-slit Hα observations of 50 low surface brightness galaxies. Of these, 36 are of sufficient quality to form rotation curves. These data provide a large increase in the number of low surface brightness galaxies for which accurate rotation curves are available. They also represent an order-of-magnitude improvement in spatial resolution over previous 21 cm studies (1″-2″ instead of 13″-45″). The improved resolution and accuracy of the data extend and strengthen the scientific conclusions previously inferred from 21 cm data.
High-Resolution Rotation Curves Of Low Surface Brightness Galaxies. Ii. Mass Models, Stacy S. Mcgaugh
High-Resolution Rotation Curves Of Low Surface Brightness Galaxies. Ii. Mass Models, Stacy S. Mcgaugh
Faculty Scholarship
We present mass models for a sample of 30 high-resolution rotation curves of low surface brightness galaxies. We fit both pseudoisothermal (core dominated) and cold dark matter (CDM; cusp dominated) halos for a wide variety of assumptions about the stellar mass-to-light ratio. We find that the pseudoisothermal model provides superior fits. CDM fits show systematic deviations from the data and often have a small statistical likelihood of being the appropriate model. The distribution of concentration parameters is too broad, and has too low a mean, to be explained by low-density, flat CDM (ACDM). This failing becomes more severe as increasing …
Mass Density Profiles Of Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Mass Density Profiles Of Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We derive the mass density profiles of dark matter halos that are implied by high spatial resolution rotation curves of low surface brightness galaxies. We find that, at small radii, the mass density distribution is dominated by a nearly constant density core with a core radius of a few kiloparsecs. For ρ(r) ∼ rα, the distribution of inner slopes α is strongly peaked around α = -0.2. This is significantly shallower than the cuspy α ≤ -1 halos found in cold dark matter simulations. While the observed distribution of α does have a tail toward such extreme values, the derived …
The Baryonic Tully-Fisher Relation, Stacy S. Mcgaugh
The Baryonic Tully-Fisher Relation, Stacy S. Mcgaugh
Faculty Scholarship
We explore the Tully-Fisher relation over five decades in stellar mass in galaxies with circular velocities ranging over 30 ≲ Vc ≲ 300 km s-1. We find a clear break in the optical Tully-Fisher relation: field galaxies with Vc ≲ 90 km s-1 fall below the relation defined by brighter galaxies. These faint galaxies, however, are very rich in gas; adding in the gas mass and plotting the baryonic disk mass Md = M* + Mgas in place of luminosity restores the single linear relation. The Tully-Fisher relation thus appears fundamentally to be a relation between rotation velocity and total …
Star Formation And Tidal Encounters With The Low Surface Brightness Galaxy Ugc 12695 And Companions, Stacy S. Mcgaugh
Star Formation And Tidal Encounters With The Low Surface Brightness Galaxy Ugc 12695 And Companions, Stacy S. Mcgaugh
Faculty Scholarship
We present VLA H I observations of the low surface brightness (LSB) galaxy UGC 12695 and its two companions, UGC 12687 and a newly discovered dwarf galaxy 2333 + 1234. UGC 12695 shows solid-body rotation but has a very lopsided morphology of the H I disk, with the majority of the H I lying in the southern arm of the galaxy. The H I column density distribution of this very blue LSB galaxy coincides in detail with its light distribution. Comparing the H I column density of UGC 12695 with the empirical (but not well-understood) value of Σc = 1021 …
Testing Modified Newtonian Dynamics With Low Surface Brightness Galaxies: Rotation Curve Fits, Stacy S. Mcgaugh
Testing Modified Newtonian Dynamics With Low Surface Brightness Galaxies: Rotation Curve Fits, Stacy S. Mcgaugh
Faculty Scholarship
We present modified Newtonian dynamics (MOND) fits to 15 rotation curves of low surface brightness (LSB) galaxies. Good fits are readily found, although for a few galaxies minor adjustments to the inclination are needed. Reasonable values for the stellar mass-to-light ratios are found, as well as an approximately constant value for the total (gas and stars) mass-to-light ratio. We show that the LSB galaxies investigated here lie on the one, unique Tully-Fisher relation, as predicted by MOND. The scatter on the Tully-Fisher relation can be completely explained by the observed scatter in the total mass-to-light ratio. We address the question …
Testing The Dark Matter Hypothesis With Low Surface Brightness Galaxies And Other Evidence, Stacy S. Mcgaugh
Testing The Dark Matter Hypothesis With Low Surface Brightness Galaxies And Other Evidence, Stacy S. Mcgaugh
Faculty Scholarship
The severity of the mass discrepancy in spiral galaxies is strongly correlated with the central surface brightness of their disks. Progressively lower surface brightness galaxies have ever larger mass discrepancies. No other parameter (luminosity, size, velocity, morphology) is so well correlated with the magnitude of the mass deficit. The rotation curves of low surface brightness disks thus provide a unique data set with which to probe the dark matter distribution in galaxies. The mass discrepancy is apparent from R = 0, giving a nearly direct map of the halo mass distribution. The luminous mass is insignificant. Interpreting the data in …
Dynamical Stability And Environmental Influences In Low Surface Brightness Disk Galaxies, Stacy S. Mcgaugh
Dynamical Stability And Environmental Influences In Low Surface Brightness Disk Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
Using analytic stability criteria we demonstrate that, because of their low surface mass density and large dark matter content, low surface brightness (LSB) disks are quite stable against the growth of global nonaxisymmetric modes such as bars. However, depending on their (poorly constrained) stellar velocity dispersions, they may be only marginally stable against local instabilities. We simulate a collision between an LSB and a high surface brightness (HSB) galaxy and find that, while the HSB galaxy forms a strong bar, the response of the LSB disk is milder, manifesting weaker rings and spiral features. The lack of sufficient disk self-gravity …
Does Low Surface Brightness Mean Low Density?, Stacy S. Mcgaugh
Does Low Surface Brightness Mean Low Density?, Stacy S. Mcgaugh
Faculty Scholarship
We compare the dynamical properties of two galaxies at identical positions on the Tully-Fisher relation, but with different surface brightnesses. We find that the low surface brightness galaxy UGC 128 has a higher mass-to-light ratio, and yet has lower mass densities than the high surface brightness galaxy NGC 2403. This is true for the gas surface density, the stellar surface density, and the total mass density. © 1996. The American Astronomical Society. All rights reserved.
Fabry-Perot Images Of Ngc 1275 And Its Puzzling High-Velocity System, Adeline Caulet, Bruce E. Woodgate, Larry W. Brown, Theodore R. Gull, Paul Hintzen, James D. Lowenthal, Ronald J. Oliversen, Michael M. Ziegler
Fabry-Perot Images Of Ngc 1275 And Its Puzzling High-Velocity System, Adeline Caulet, Bruce E. Woodgate, Larry W. Brown, Theodore R. Gull, Paul Hintzen, James D. Lowenthal, Ronald J. Oliversen, Michael M. Ziegler
Astronomy: Faculty Publications
We report the first images obtained with the Goddard Fabry-Perot imager, a very sensitive and tunable imaging system designed to achieve the high levels of performance required in the optical studies of faint emission-line extragalactic objects. A velocity sequence of calibrated narrow-band CCD images (FWHM ∼7 Å) has been obtained to cover the 3000 km s-1 velocity space between the redshifted Hα emission lines of NGC 1275 (the central dominant galaxy of the Perseus Cluster), its extended associated system of low-velocity (LV) filaments and the high-velocity (HV) system of knots, projected on the same line of sight in the sky. …