Physical Sciences and Mathematics | Open Access Articles

Creation Of Peanut-Shaped Bulges Via The Slow Mode Of Bar Growth, Michael S. Peterson, Martin D. Weinberg, Neal S. Katz

Neal S. Katz

Recent theoretical work has implicated fast bar formation modes and subsequent evolution as the creation mechanism for the observed peanut-shaped bulges in some edge-on disk galaxies. We demonstrate an N-body simulation of a disk undergoing a contrasting slow mode of bar growth, unsubjected to a buckling instability, which nonetheless grows the 4:1 orbit family responsible for a peanut-shaped bulge. We also present a simulation with fast mode bar growth, which exhibits thickening similar to other work. A novel orbit classification method that finds dynamically distinct families is presented, allowing for a detailed analysis of angular momentum transfer channels within the …

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Star Formation And Stellar Mass Assembly In Dark Matter Halos: From Giants To Dwarfs, Zhankui Lu, H.J. Mo, Yu Lu, Neal S. Katz, Martin D. Weinberg, Frank C. Van Den Bosch, Xiaohu Yang

Neal S. Katz

The empirical model of Lu et al. is updated with recent data of galaxy stellar mass functions (SMFs). The model predicts that the slope of galaxy SMFs at z > 2 should be quite steep at the low-mass end, beyond the current detection limit, and it is a strong prediction that can be tested against future observations. The model is used to investigate the galaxy star formation and assembly or merger histories in detail. Most of the stars in cluster centrals, corresponding to brightest cluster galaxies in observations, formed earlier than z ≈ 2 but have been assembled much later. Typically, …

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Budget And Accounting Of Metals At Z~0: Results From The Cos-Halos Survey, Molly S. Peeples, Jessica K. Werk, Jason Tumlinson, Benjamin D. Oppenheimer, J. Xavier Prochaska, Neal S. Katz, David H. Weinberg

Neal S. Katz

We present a budget and accounting of metals in and around star-forming galaxies at z ~ 0. We combine empirically derived star formation histories with updated supernova and asymptotic giant branch yields and rates to estimate the total mass of metals produced by galaxies with present-day stellar mass of 109.3-1011.6 M☉. On the accounting side of the ledger, we show that a surprisingly constant 20%-25% mass fraction of produced metals remain in galaxies' stars, interstellar gas and interstellar dust, with little dependence of this fraction on the galaxy stellar mass (omitting those metals immediately locked up in remnants). Thus, the …

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An Empirical Model For The Star Formation History In Dark Matter Halos, Zhankui Lu, H. J. Mo, Yu Lu, Neal S. Katz, Martin D. Weinberg, Frank C. Van Den Bosch, Xiaohu Yang

Neal S. Katz

We develop an empirical approach to infer the star formation rate in dark matter haloes from the galaxy stellar mass function (SMF) at different redshifts and the local cluster galaxy luminosity function (CGLF), which has a steeper faint end relative to the SMF of local galaxies. As satellites are typically old galaxies which have been accreted earlier, this feature can cast important constraint on the formation of low-mass galaxies at high redshift. The evolution of the SMFs suggests the star formation in high-mass haloes (>1012 h−1 M⊙) has to be boosted at high redshift beyond what is expected from …

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Bayesian Inferences Of Galaxy Formation From The K-Band Luminosity And Hi Mass Functions Of Galaxies: Constraining Star Formation And Feedback, Yu Lu, H.J. Mo, Zhankui Lu, Neal S. Katz, Martin D. Weinberg

Neal S. Katz

We infer mechanisms of galaxy formation for a broad family of semi-analytic models (SAMs) constrained by the K-band luminosity function and H I mass function of local galaxies using tools of Bayesian analysis. Even with a broad search in parameter space the whole model family fails to match to constraining data. In the best-fitting models, the star formation and feedback parameters in low-mass haloes are tightly constrained by the two data sets, and the analysis reveals several generic failures of models that similarly apply to other existing SAMs. First, based on the assumption that baryon accretion follows the dark matter …

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Parametrising Star Formation Histories, Vimal Simha, David H. Weinberg, Charlie Conroy, Romeel Dave, Mark Fardal, Neal S. Katz, Benjamin D. Oppenheimer

Neal S. Katz

No abstract provided.

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Tracing Inflows And Outlflows With Absorption Lines In Circumgalactic Gas, Amanda Brady Ford, Romeel Dave, Benjamin D. Oppenheimer, Neal S. Katz, Juna A. Kollmeier, Robert Thompson, David H. Weinberg

Neal S. Katz

We examine how H I and metal absorption lines within low-redshift galaxy haloes trace the dynamical state of circumgalactic gas, using cosmological hydrodynamic simulations that include a well-vetted heuristic model for galactic outflows. We categorize inflowing, outflowing, and ambient gas based on its history and fate as tracked in our simulation. Following our earlier work, showing that the ionization level of absorbers was a primary factor in determining the physical conditions of absorbing gas, we show here that it is also a governing factor for its dynamical state. Low-ionization metal absorbers (e.g. Mg II) tend to arise in gas that …

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The Photon Underproduction Crisis, Juna A. Kollmeier, David H. Weinberg, Benjamin D. Oppenheimer, Francesco Haardt, Neal S. Katz, Rameel A. Dave, Mark Fardal, Piero Madau, Charles Danforth, Amanda B. Ford, Molly S. Peeples, Joseph Mcewen

Neal S. Katz

We examine the statistics of the low-redshift Lyα forest from smoothed particle hydrodynamic simulations in light of recent improvements in the estimated evolution of the cosmic ultraviolet background (UVB) and recent observations from the Cosmic Origins Spectrograph (COS). We find that the value of the metagalactic photoionization rate (ΓHI) required by our simulations to match the observed properties of the low-redshift Lyα forest is a factor of five larger than the value predicted by state-of-the art models for the evolution of this quantity. This mismatch in ΓHI results in the mean flux decrement of the Lyα forest being overpredicted by …

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The Cos-Halos Survey: Physical Conditions And Baryonic Mass In The Low-Redshift Circumgalactic Medium, Jessica K. Werk, J. Xavier Prochaska, Jason Tumlinson, Molly S. Peeples, Todd M. Tripp, Andrew J. Fox, Nicolas Lehner, Christopher Thom, John M. O'Meara, Amanda Brady Ford, Rongmon Bordoloi, Neal S. Katz, Nicolas Tejos, Benjamin D. Oppenheimer, Romeel Dave, David H. Weinberg

Neal S. Katz

We analyze the physical conditions of the cool, photoionized (T ~104 K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos within 160 kpc of L ~ L* galaxies at z ~ 0.2. These data are well described by simple photoionization models, with the gas highly ionized (n H II /n H gsim 99%) by the extragalactic ultraviolet background. Scaling by estimates for the virial radius, R vir, we show that the ionization state (tracked by the dimensionless ionization parameter, U) increases with distance from the host galaxy. The ionization parameters imply a …

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The Cos-Dwarfs Survey: The Carbon Reservoir Around Sub-L Galaxies, Rongmon Bordoloi, Jason Tumlinson, Jessica K. Werk, Benjamin D. Oppenheimer, Molly S. Peeples, J. Xavier Prochaska, Todd M. Tripp, Neal S. Katz, Romeel Dave, Andrew J. Fox, Christopher Thom, Amanda Brady Ford, David H. Weinberg, Joseph N. Burchett, Juna A. Kollmeier

Neal S. Katz

We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z ≤ 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected one-dimensional and two-dimensional distribution of C iv absorption, we find that C iv is detected out to ≈100 kpc (corresponding roughly to ≈0.5 Rvir) of the host galaxies. The C iv absorption strength falls off radially as a power law, and beyond ≈0.5 Rvir, no C iv absorption is detected above our sensitivity limit of ≈50–100 mÅ. We find a tentative correlation between …

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The Neutral Hydrogen Content Of Galaxies In Cosmological Hydrodynamic Simulations, Romeel Dave, Neal S. Katz, Benjamin D. Oppenheimer, Juna A. Kollmeier, David H. Weinberg

Neal S. Katz

We examine the global H I properties of galaxies in quarter billion particle cosmological simulations using GADGET-2, focusing on how galactic outflows impact H I content. We consider four outflow models, including a new one (ezw) motivated by recent interstellar medium simulations in which the wind speed and mass loading factor scale as expected for momentum-driven outflows for larger galaxies and energy-driven outflows for dwarfs (σ < 75 km s−1). To obtain predicted H I masses, we employ a simple but effective local correction for particle self-shielding and an observationally constrained transition from neutral to molecular hydrogen. Our ezw simulation produces an H I mass function whose faint-end slope of −1.3 agrees well with observations from the Arecibo Fast Legacy ALFA survey; other models agree less well. Satellite galaxies have a bimodal distribution in H I fraction versus halo mass, with smaller satellites and/or those in larger haloes more often being H I deficient. At a given stellar mass, H I content correlates with the star formation rate and inversely correlates with metallicity, as expected if driven by stochasticity in the accretion rate. To higher redshifts, massive H I galaxies disappear and the mass function steepens. The global cosmic H I density conspires to remain fairly constant from z ∼ 5 → 0, but the relative contribution from smaller galaxies increases with redshift.

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Full-Text Articles in Physical Sciences and Mathematics

Creation Of Peanut-Shaped Bulges Via The Slow Mode Of Bar Growth, Michael S. Peterson, Martin D. Weinberg, Neal S. Katz

Neal S. Katz

Star Formation And Stellar Mass Assembly In Dark Matter Halos: From Giants To Dwarfs, Zhankui Lu, H.J. Mo, Yu Lu, Neal S. Katz, Martin D. Weinberg, Frank C. Van Den Bosch, Xiaohu Yang

Neal S. Katz

Budget And Accounting Of Metals At Z~0: Results From The Cos-Halos Survey, Molly S. Peeples, Jessica K. Werk, Jason Tumlinson, Benjamin D. Oppenheimer, J. Xavier Prochaska, Neal S. Katz, David H. Weinberg

Neal S. Katz

An Empirical Model For The Star Formation History In Dark Matter Halos, Zhankui Lu, H. J. Mo, Yu Lu, Neal S. Katz, Martin D. Weinberg, Frank C. Van Den Bosch, Xiaohu Yang

Neal S. Katz

Bayesian Inferences Of Galaxy Formation From The K-Band Luminosity And Hi Mass Functions Of Galaxies: Constraining Star Formation And Feedback, Yu Lu, H.J. Mo, Zhankui Lu, Neal S. Katz, Martin D. Weinberg

Neal S. Katz

Parametrising Star Formation Histories, Vimal Simha, David H. Weinberg, Charlie Conroy, Romeel Dave, Mark Fardal, Neal S. Katz, Benjamin D. Oppenheimer

Neal S. Katz

Tracing Inflows And Outlflows With Absorption Lines In Circumgalactic Gas, Amanda Brady Ford, Romeel Dave, Benjamin D. Oppenheimer, Neal S. Katz, Juna A. Kollmeier, Robert Thompson, David H. Weinberg

Neal S. Katz

The Photon Underproduction Crisis, Juna A. Kollmeier, David H. Weinberg, Benjamin D. Oppenheimer, Francesco Haardt, Neal S. Katz, Rameel A. Dave, Mark Fardal, Piero Madau, Charles Danforth, Amanda B. Ford, Molly S. Peeples, Joseph Mcewen

Neal S. Katz

Neal S. Katz

Neal S. Katz

The Neutral Hydrogen Content Of Galaxies In Cosmological Hydrodynamic Simulations, Romeel Dave, Neal S. Katz, Benjamin D. Oppenheimer, Juna A. Kollmeier, David H. Weinberg

Neal S. Katz