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Articles 31 - 60 of 116
Full-Text Articles in Astrophysics and Astronomy
Testing The Strong Equivalence Principle: Detection Of The External Field Effect In Rotationally Supported Galaxies, Stacy S. Mcgaugh, Pengfei Li
Testing The Strong Equivalence Principle: Detection Of The External Field Effect In Rotationally Supported Galaxies, Stacy S. Mcgaugh, Pengfei Li
Faculty Scholarship
The strong equivalence principle (SEP) distinguishes general relativity (GR) from other viable theories of gravity. The SEP demands that the internal dynamics of a self-gravitating system under freefall in an external gravitational field should not depend on the external field strength. We test the SEP by investigating the external field effect (EFE) in Milgromian dynamics (MOND), proposed as an alternative to dark matter in interpreting galactic kinematics. We report a detection of this EFE using galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) sample together with estimates of the large-scale external gravitational field from an all-sky galaxy catalog. …
Self-Consistent Color-Stellar Mass-To-Light Ratio Relations For Low Surface Brightness Galaxies, Wei Du, Stacy S. Mcgaugh
Self-Consistent Color-Stellar Mass-To-Light Ratio Relations For Low Surface Brightness Galaxies, Wei Du, Stacy S. Mcgaugh
Faculty Scholarship
The color-stellar mass-to-light ratio relation (CMLR) is a widely accepted tool for estimating the stellar mass (M ∗) of a galaxy. However, an individual CMLR tends to give distinct M ∗ for a same galaxy when it is applied in different bands. Examining five representative CMLRs from the literature, we find that the difference in M ∗ predicted in different bands from optical to near-infrared by a CMLR is 0.1 ∼ 0.3 dex. Based on a sample of low surface brightness galaxies that covers a wide range of color and luminosity, we therefore recalibrated each original CMLR in r, i, …
Using The Baryonic Tully–Fisher Relation To Measure Ho, Stacy S. Mcgaugh
Using The Baryonic Tully–Fisher Relation To Measure Ho, Stacy S. Mcgaugh
Faculty Scholarship
We explore the use of the baryonic Tully-Fisher relation (bTFR) as a new distance indicator. Advances in near-IR imaging and stellar population models, plus precise rotation curves, have reduced the scatter in the bTFR such that distance is the dominant source of uncertainty. Using 50 galaxies with accurate distances from Cepheids or the tip magnitude of the red giant branch, we calibrate the bTFR on a scale independent of H o . We then apply this calibrated bTFR to 95 independent galaxies from the SPARC sample, using CosmicFlows-3 velocities, to deduce the local value of H o . We find …
Predictions And Outcomes For The Dynamics Of Rotating Galaxies, Stacy S. Mcgaugh
Predictions And Outcomes For The Dynamics Of Rotating Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
A review is given of a priori predictions made for the dynamics of rotating galaxies. One theory-MOND-has had many predictions corroborated by subsequent observations. While it is sometimes possible to offer post hoc explanations for these observations in terms of dark matter, it is seldom possible to use dark matter to predict the same phenomena.
A Comprehensive Catalog Of Dark Matter Halo Models For Sparc Galaxies, Pengfei Li, Stacy S. Mcgaugh
A Comprehensive Catalog Of Dark Matter Halo Models For Sparc Galaxies, Pengfei Li, Stacy S. Mcgaugh
Faculty Scholarship
We present rotation curve fits to 175 late-type galaxies from the Spitzer Photometry and Accurate Rotation Curves database using seven dark matter (DM) halo profiles: pseudo-isothermal, Burkert, Navarro-Frenk-White (NFW), Einasto, Di Cintio et al. (2014, hereafter DC14), cored-NFW, and a new semi-empirical profile named Lucky13. We marginalize over the stellar mass-to-light ratio, galaxy distance, disk inclination, halo concentration, and halo mass (and an additional shape parameter for Einasto) using a Markov Chain Monte Carlo method. We find that cored halo models, such as the DC14 and Burkert profiles, generally provide better fits to rotation curves than the cuspy NFW profile. …
Tracing The Dynamical Mass In Galaxy Disks Using H I Velocity Dispersion And Its Implications For The Dark Matter Distribution In Galaxies, Stacy S. Mcgaugh
Tracing The Dynamical Mass In Galaxy Disks Using H I Velocity Dispersion And Its Implications For The Dark Matter Distribution In Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We present a method to derive the dynamical mass of face-on galaxy disks using their neutral hydrogen (H i) velocity dispersion (σ H i). We have applied the method to nearby, gas-rich galaxies that have extended H i gas disks and have low inclinations. The galaxy sample includes four large disk galaxies, NGC 628, NGC 6496, NGC 3184, and NGC 4214, and three dwarf galaxies, DDO 46, DDO 63, and DDO 187. We have used archival H i data from The H i Nearby Galaxy Survey (THINGS) and the LITTLE THINGS survey to derive the H i gas distributions and …
The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh
The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh
Faculty Scholarship
We present an empirical method to measure the halo mass function (HMF) of galaxies. We determine the relation between the H i line width from single-dish observations and the dark matter halo mass (M 200) inferred from rotation-curve fits in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database, then we apply this relation to galaxies from the H i Parkes All Sky Survey (HIPASS) to derive the HMF. This empirical HMF is well fit by a Schechter function, and matches that expected in the Λ Cold Dark Matter (ΛCDM) model over the range 1010.5 < M 200 < 1012 M o˙. More massive halos must be poor in neutral gas to maintain consistency with the power law predicted by ΛCDM. We detect no discrepancy at low masses. The lowest halo mass probed by HIPASS, however, is just greater than the mass scale where the Local Group missing satellite problem sets in. The integrated mass density associated with the dark matter halos of H i-detected galaxies sums to Ωm,gal ≈ 0.03 over the probed mass range.
The Imprint Of Spiral Arms On The Galactic Rotation Curve, Stacy S. Mcgaugh
The Imprint Of Spiral Arms On The Galactic Rotation Curve, Stacy S. Mcgaugh
Faculty Scholarship
We discuss a model for the Milky Way obtained by fitting the observed terminal velocities with the radial acceleration relation. The resulting stellar surface density profile departs from a smooth exponential disk, having bumps and wiggles that correspond to massive spiral arms. These features are used to estimate the term for the logarithmic density gradient in the Jeans equation, which turn out to have exactly the right location and amplitude to reconcile the apparent discrepancy between the stellar rotation curve and that of the interstellar gas. This model also predicts a gradually declining rotation curve outside the solar circle with …
Predictions For The Sky-Averaged Depth Of The 21 Cm Absorption Signal At High Redshift In Cosmologies With And Without Nonbaryonic Cold Dark Matter, Stacy S. Mcgaugh
Predictions For The Sky-Averaged Depth Of The 21 Cm Absorption Signal At High Redshift In Cosmologies With And Without Nonbaryonic Cold Dark Matter, Stacy S. Mcgaugh
Faculty Scholarship
We consider the 21 cm absorption signal expected at high redshift in cosmologies with and without nonbaryonic cold dark matter. The expansion of the early Universe decelerates strongly with dark matter, but approximately coasts without it. This results in a different path length across the epochs when absorption is expected, with the consequence that the absorption is predicted to be a factor of ∼2 greater without dark matter than with it. Observation of such a signal would motivate consideration of extended theories of gravity in lieu of dark matter.
Fitting The Radial Acceleration Relation To Individual Sparc Galaxies, Pengfei Li, Stacy Mcgaugh
Fitting The Radial Acceleration Relation To Individual Sparc Galaxies, Pengfei Li, Stacy Mcgaugh
Faculty Scholarship
Galaxies follow a tight radial acceleration relation (RAR): the acceleration observed at every radius correlates with that expected from the distribution of baryons. We use the Markov chain Monte Carlo method to fit the mean RAR to 175 individual galaxies in the SPARC database, marginalizing over stellar mass-to-light ratio (γ ∗), galaxy distance, and disk inclination. Acceptable fits with astrophysically reasonable parameters are found for the vast majority of galaxies. The residuals around these fits have an rms scatter of only 0.057 dex (~13%). This is in agreement with the predictions of modified Newtonian dynamics (MOND). We further consider a …
The Star-Forming Main Sequence Of Dwarf Low Surface Brightness Galaxies, Stacy S. Mcgaugh
The Star-Forming Main Sequence Of Dwarf Low Surface Brightness Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We explore the star-forming properties of late-type, low surface brightness (LSB) galaxies. The star-forming main sequence (SFR-M∗) of LSB dwarfs has a steep slope, indistinguishable from unity (1.04 ± 0.06). They form a distinct sequence from more massive spirals, which exhibit a shallower slope. The break occurs around M∗ ≈ 1010 Mo , and can also be seen in the gas mass-stellar mass plane. The global Kennicutt-Schmidt law (SFR-Mg) has a slope of 1.47 ± 0.11 without the break seen in the main sequence. There is an ample supply of gas in LSB galaxies, which have gas depletion times well …
The Extended Baryonic Halo Of Ngc 3923, Stacy S. Mcgaugh, J. Christopher Mihos
The Extended Baryonic Halo Of Ngc 3923, Stacy S. Mcgaugh, J. Christopher Mihos
Faculty Scholarship
Galaxy halos and their globular cluster systems build up over time by the accretion of small satellites. We can learn about this process in detail by observing systems with ongoing accretion events and comparing the data with simulations. Elliptical shell galaxies are systems that are thought to be due to ongoing or recent minor mergers. We present preliminary results of an investigation of the baryonic halo-light profile, globular clusters, and shells/streams-of the shell galaxy NGC 3923 from deep Dark Energy Camera (DECam) g and i-band imaging. We present the 2D and radial distributions of the globular cluster candidates out to …
One Law To Rule Them All: The Radial Acceleration Relation Of Galaxies, Federico Lelli, Stacy S. Mcgaugh, Marcel S. Pawlowski
One Law To Rule Them All: The Radial Acceleration Relation Of Galaxies, Federico Lelli, Stacy S. Mcgaugh, Marcel S. Pawlowski
Faculty Scholarship
We study the link between baryons and dark matter (DM) in 240 galaxies with spatially resolved kinematic data. Our sample spans 9 dex in stellar mass and includes all morphological types. We consider (1) 153 late-type galaxies (LTGs; spirals and irregulars) with gas rotation curves from the SPARC database, (2) 25 early-type galaxies (ETGs; ellipticals and lenticulars) with stellar and H i data from ATLAS or X-ray data from Chandra, and (3) 62 dwarf spheroidals (dSphs) with individual-star spectroscopy. We find that LTGs, ETGs, and "classical" dSphs follow the same radial acceleration relation: the observed acceleration (gobs) correlates with that …
Spitzer's View Of The Candidate Cluster And Protocluster Catalog (Ccpc), J. R. Franck, Stacy S. Mcgaugh
Spitzer's View Of The Candidate Cluster And Protocluster Catalog (Ccpc), J. R. Franck, Stacy S. Mcgaugh
Faculty Scholarship
The Candidate Cluster and Protocluster Catalog contains 218 galaxy overdensities composed of more than 2000 galaxies with spectroscopic redshifts spanning the first few Gyr after the Big Bang (2.0 ≤ z < 6.6). We use Spitzer archival data to track the underlying stellar mass of these overdense regions in various temporal cross sections by building rest-frame near-infrared luminosity functions (LFs) across the span of redshifts. This exercise maps the stellar growth of protocluster galaxies, as halos in the densest environments should be the most massive from hierarchical accretion. The characteristic apparent magnitude, m∗(z), is relatively flat from 2.0 ≤ z < 6.6, consistent with a passive evolution of an old stellar population. This trend maps smoothly to lower redshift results of cluster galaxies from other works. We find no difference in the LFs of galaxies in the field versus protoclusters at a given redshift apart from their density.
The Candidate Cluster And Protocluster Catalog (Ccpc). Ii. Spectroscopically Identified Structures Spanning 2 < Z < 6.6, J. R. Franck, Stacy S. Mcgaugh
The Candidate Cluster And Protocluster Catalog (Ccpc). Ii. Spectroscopically Identified Structures Spanning 2 < Z < 6.6, J. R. Franck, Stacy S. Mcgaugh
Faculty Scholarship
The Candidate Cluster and Protocluster Catalog (CCPC) is a list of objects at redshifts z > 2 composed of galaxies with spectroscopically confirmed redshifts that are coincident on the sky and in redshift. These protoclusters are identified by searching for groups in volumes corresponding to the expected size of the most massive protoclusters at these redshifts. In CCPC1 we identified 43 candidate protoclusters among 14,000 galaxies between 2.74 < z < 3.71. Here we expand our search to more than 40,000 galaxies with spectroscopic redshifts z > 2.00, resulting in an additional 173 candidate structures. The most significant of these are 36 protoclusters with overdensities δ gal > 7. We also identify three large proto-supercluster candidates containing multiple protoclusters at z …
Mond Prediction For The Velocity Dispersion Of The "Feeble Giant" Crater Ii, Stacy S. Mcgaugh
Mond Prediction For The Velocity Dispersion Of The "Feeble Giant" Crater Ii, Stacy S. Mcgaugh
Faculty Scholarship
Crater II is an unusual object among the dwarf satellite galaxies of the Local Group in that it has a very large size for its small luminosity. This provides a strong test of MOND, as Crater II should be in the deep MOND regime (g in ≈ 34 km2 s-2 kpc-1 ≪ a 0 = 3700 km2 s-2 kpc-1). Despite its great distance (≈120 kpc) from the Milky Way, the external field of the host (g ex ≈ 282 km2 s-2 kpc-1) comfortably exceeds the internal field. Consequently, Crater II should be subject to the external field effect, a feature …
Sparc: Mass Models For 175 Disk Galaxies With Spitzer Photometry And Accurate Rotation Curves, Federico Lelli, Stacy S. Mcgaugh
Sparc: Mass Models For 175 Disk Galaxies With Spitzer Photometry And Accurate Rotation Curves, Federico Lelli, Stacy S. Mcgaugh
Faculty Scholarship
We introduce SPARC (Spitzer Photometry and Accurate Rotation Curves): a sample of 175 nearby galaxies with new surface photometry at 3.6 μm and high-quality rotation curves from previous H I/Hα studies. SPARC spans a broad range of morphologies (S0 to Irr), luminosities (∼5 dex), and surface brightnesses (∼4 dex). We derive [3.6] surface photometry and study structural relations of stellar and gas disks. We find that both the stellar mass-H I mass relation and the stellar radius-H i radius relation have significant intrinsic scatter, while the H I mass-radius relation is extremely tight. We build detailed mass models and quantify …
Radial Acceleration Relation In Rotationally Supported Galaxies, Stacy S. Mcgaugh, Federico Lelli
Radial Acceleration Relation In Rotationally Supported Galaxies, Stacy S. Mcgaugh, Federico Lelli
Faculty Scholarship
We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.
The Relation Between Stellar And Dynamical Surface Densities In The Central Regions Of Disk Galaxies, Federico Lelli, Stacy S. Mcgaugh, Marcel S. Pawlowski
The Relation Between Stellar And Dynamical Surface Densities In The Central Regions Of Disk Galaxies, Federico Lelli, Stacy S. Mcgaugh, Marcel S. Pawlowski
Faculty Scholarship
We use the Spitzer Photometry and Accurate Rotation Curves (SPARC) database to study the relation between the central surface density of stars and dynamical mass in 135 disk galaxies (S0 to dIrr). We find that correlates tightly with over 4 dex. This central density relation can be described by a double power law. High surface brightness galaxies are consistent with a 1:1 relation, suggesting that they are self-gravitating and baryon dominated in the inner parts. Low surface brightness (LSB) galaxies systematically deviate from the 1:1 line, indicating that the dark matter contribution progressively increases but remains tightly coupled to the …
The Candidate Cluster And Protocluster Catalog (Ccpc) Of Spectroscopically Identified Structures Spanning 2.74 < Z < 3.71, J. R. Franck, Stacy S. Mcgaugh
The Candidate Cluster And Protocluster Catalog (Ccpc) Of Spectroscopically Identified Structures Spanning 2.74 < Z < 3.71, J. R. Franck, Stacy S. Mcgaugh
Faculty Scholarship
We developed a search methodology to identify galaxy protoclusters at z > 2.74 and implemented it on a sample of ∼14,000 galaxies with previously measured redshifts. The results of this search are recorded in the Candidate Cluster and Protocluster Catalog (CCPC). The catalog contains 12 clusters that are highly significant overdensities (δgal > 7), 6 of which were previously known. We also identify another 31 candidate protoclusters (including four previously identified structures) of lower overdensities. CCPC systems vary over a wide range of physical sizes and shapes, from small, compact groups to large, extended, and filamentary collections of galaxies. This variety persists …
The Small Scatter Of The Baryonic Tully-Fisher Relation, Federico Lelli, Stacy S. Mcgaugh
The Small Scatter Of The Baryonic Tully-Fisher Relation, Federico Lelli, Stacy S. Mcgaugh
Faculty Scholarship
In a Γ cold dark matter (ΓCDM) cosmology, the baryonic TullyFisher relation (BTFR) is expected to show significant intrinsic scatter resulting from the massconcentration relation of dark matter halos and the baryonic-tohalo mass ratio. We study the BTFR using a sample of 118 disk galaxies (spirals and irregulars) with data of the highest quality: extended H I rotation curves (tracing the outer velocity) and Spitzer photometry at 3.6 μm (tracing the stellar mass). Assuming that the stellar mass-to-light ratio (Υ∗) is nearly constant at 3.6 μm, we find that the scatter, slope, and normalization of the BTFR systematically vary with …
The Surface Density Profile Of The Galactic Disk From The Terminal Velocity Curve, Stacy S. Mcgaugh
The Surface Density Profile Of The Galactic Disk From The Terminal Velocity Curve, Stacy S. Mcgaugh
Faculty Scholarship
The mass distribution of the Galactic disk is constructed from the terminal velocity curve and the mass discrepancy-acceleration relation. Mass models numerically quantifying the detailed surface density profiles are tabulated. For R0 = 8 kpc, the models have stellar mass 5 < M∗ < 6 × 1010 , scale length 2.0 ≤ Rd ≤ 2.9 kpc, LSR circular velocity 222 ≤ Θ0 ≤ 233 , and solar circle stellar surface density 34 ≤ Σd(R0) ≤ 61 . The present interarm location of the solar neighborhood may have a somewhat lower stellar surface density than average for the solar circle. The Milky Way appears to be a normal spiral galaxy that obeys scaling relations like the Tully-Fisher relation, the size-mass relation, and the disk maximality-surface brightness relation. The stellar disk is maximal, and the spiral arms are massive. The bumps and wiggles in the terminal velocity curve correspond to known spiral features (e.g., the Centaurus arm is a ∼50% overdensity). The rotation curve switches between positive and negative over scales of hundreds of parsecs. The rms amplitude , implying that commonly neglected terms in the Jeans equations may be nonnegligible. The spherically averaged local dark matter density is ρ0,DM ≈ 0.009 (0.34 ). Adiabatic compression of the dark matter halo may help reconcile the Milky Way with the c-V200 relation expected in ΛCDM while also helping to mitigate the too-big-to-fail problem, but it remains difficult to reconcile the inner bulge/bar-dominated region with a cuspy halo. We note that NGC 3521 is a near twin to the Milky Way, having a similar luminosity, scale length, and rotation curve.
Gas Dynamics In Tidal Dwarf Galaxies: Disc Formation At Z = 0, Federico Lelli, Stacy Mcgaugh
Gas Dynamics In Tidal Dwarf Galaxies: Disc Formation At Z = 0, Federico Lelli, Stacy Mcgaugh
Faculty Scholarship
Tidal dwarf galaxies (TDGs) are recycled objects that form within the collisional debris of interacting and merging galaxies. They are expected to be devoid of non-baryonic dark matter, since they can only form from dissipative material ejected from the discs of the progenitor galaxies. We investigate the gas dynamics in a sample of six bona fide TDGs around three interacting and post-interacting systems: NGC 4694, NGC 5291, and NGC 7252 ("Atoms for Peace"). For NGC 4694 and NGC 5291, we analyse existing HI data from the Very Large Array (VLA),while for NGC 7252 we present new HI observations from the …
Stellar Populations And The Star Formation Histories Of Lsb Galaxies. V. Wfc3 Color-Magnitude Diagrams, Stacy S. Mcgaugh
Stellar Populations And The Star Formation Histories Of Lsb Galaxies. V. Wfc3 Color-Magnitude Diagrams, Stacy S. Mcgaugh
Faculty Scholarship
We present WFC3 observations of three low surface brightness (LSB) galaxies from the Schombert et al. LSB catalog that are within 11 Mpc of the Milky Way. Deep imaging at F336W, F555W, and F814W allow the construction of the V - I color-magnitude diagrams (CMD) to MI = -2. Overall 1869, 465, and 501 stellar sources are identified in the three LSB galaxies F415-3, F608-1, and F750-V1, respectively. The spatial distribution of young blue stars matches the H maps from ground-based imaging, indicating that star formation in LSB galaxies follows the same style as in other irregular galaxies. Several star …
Three Candidate Clusters Around High Redshift Radio-Loud Sources: Mg1 J04426+0202, 3c 068.2, And Ms 1426.9+1052, J. R. Franck, Stacy S. Mcgaugh
Three Candidate Clusters Around High Redshift Radio-Loud Sources: Mg1 J04426+0202, 3c 068.2, And Ms 1426.9+1052, J. R. Franck, Stacy S. Mcgaugh
Faculty Scholarship
We present near-infrared observations of the environments around three radio-loud sources (MG1 J0442+0202, 3C 068.2, and MS 1426.9+1052) at redshifts z = 1.10, 1.57, and 1.83 (respectively).,Qthat are surrounded by nearinfrared galaxy overdensities. Overdensities with respect to field counts were found to be significant up to 19£m, with 12 times the expected number of galaxies within the inner regions of the densest proto-cluster. Color¡V magnitude relations are constructed in Ks, J . Ks, with each candidate cluster exhibiting a feature consistent with the beginnings of a red sequence (RS). Galaxy models based on the redshift of the radio source are …
Weighing Galaxy Disks With The Baryonic Tully-Fisher Relation, Stacy S. Mcgaugh
Weighing Galaxy Disks With The Baryonic Tully-Fisher Relation, Stacy S. Mcgaugh
Faculty Scholarship
We estimate the stellar masses of disk galaxies with two independent methods: a photometrically self-consistent color?mass-to-light ratio relation (CMLR) from population synthesis models, and the baryonic Tully?Fisher relation (BTFR) calibrated by gas-rich galaxies. These two methods give consistent results. The CMLR correctly converts distinct Tully?Fisher relations in different bands into the same BTFR. The BTFR is consistent with Mb ∝ Vf4 over nearly six decades in mass, with no hint of a change in slope over that range. The intrinsic scatter in the BTFR is negligible, implying that the IMF of disk galaxies is effectively universal. The gas-rich BTFR suggests …
The Third Law Of Galactic Rotation, Stacy S. Mcgaugh
The Third Law Of Galactic Rotation, Stacy S. Mcgaugh
Faculty Scholarship
I review the connection between dynamics and the baryonic mass distribution in rotationally-supported galaxies. The enclosed dynamical mass-to-light ratio increases with decreasing galaxy luminosity and surface brightness. The correlation with surface brightness appears to be the more fundamental, with the dependence on luminosity following simply from the weaker correlation between luminosity and surface brightness. In addition to this global relation, there is also a local relation between the amplitude of the mass discrepancy and the acceleration predicted by the observed distribution of baryons. I provide an empirical calibration of this mass discrepancy-acceleration relation. The data are consistent with the operation …
Color-Mass-To-Light-Ratio Relations For Disk Galaxies, Stacy S. Mcgaugh
Color-Mass-To-Light-Ratio Relations For Disk Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We combine Spitzer 3.6 μm observations of a sample of disk galaxies spanning over 10 mag in luminosity with optical luminosities and colors to test population synthesis prescriptions for computing stellar mass. Many commonly employed models fail to provide self-consistent results: the stellar mass estimated from the luminosity in one band can differ grossly from that of another band for the same galaxy. Independent models agree closely in the optical (V band), but diverge at longer wavelengths. This effect is particularly pronounced in recent models with substantial contributions from TP-AGB stars. We provide revised color-mass-to-light ratio relations that yield self-consistent …
Co-Orbiting Planes Of Sub-Halos Are Similarly Unlikely Around Paired And Isolated Hosts, Marcel S. Pawlowski, Stacy S. Mcgaugh
Co-Orbiting Planes Of Sub-Halos Are Similarly Unlikely Around Paired And Isolated Hosts, Marcel S. Pawlowski, Stacy S. Mcgaugh
Faculty Scholarship
Sub-halos in dark-matter-based cosmological simulations tend to be distributed approximately isotropically around their host. The existence of highly flattened, co-orbiting planes of satellite galaxies has therefore been identified as a possible problem for these cosmological models, but so far studies have not considered the hosts' environments. That satellite planes are now known around both major galaxies in the Local Group raises the question whether they are more likely to be found around paired hosts. In a first attempt to investigate this possibility, we focus on the flattening and orbital coherence of the 11 brightest satellite galaxies of the vast polar …
The Inner Dynamical Mass Across Galaxy Morphology: A Weak Scaling With Total Stellar Mass, Stacy S. Mcgaugh
The Inner Dynamical Mass Across Galaxy Morphology: A Weak Scaling With Total Stellar Mass, Stacy S. Mcgaugh
Faculty Scholarship
We compile a sample of dispersion-supported and rotation-supported galaxies for which the dynamical mass enclosed at 500 pc can be measured. We find that this dynamical quantity increases only slowly with stellar mass (Mtotal(500 pc) ? M0.16 stars ) over ?9 decades in baryonic mass and ?3 in length scale, with a sudden upturn at the highest masses (Mstars - 1010 M-). This upturn occurs for the earliest types (S0 and Sa) of disk galaxies, and is consistent with the extra mass within 500 pc being predominantly stellar. This sudden change may be indicative of different bulge formation mechanisms between …