Jeremiah P. Ostriker

Princeton University, Princeton, New Jersey, United States

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Publications (374)2096.19 Total impact

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    Hy Trac, Paul Bode, Jeremiah P. Ostriker
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    ABSTRACT: We present templates for the Sunyaev-Zel'dovich (SZ) angular power spectrum based on four models for the nonlinear gas distribution. The frequency-dependent SZ temperature fluctuations, with thermal (TSZ) and kinetic (KSZ) contributions, are calculated by tracing through a dark matter simulation, processed to include gas in dark matter halos and in the filamentary intergalactic medium. Different halo gas models are compared to study how star formation, energetic feedback, and nonthermal pressure support influence the angular power spectrum. The standard model has been calibrated to reproduce the stellar and gas fractions and X-ray scaling relations measured from low redshift clusters and groups. The other models illustrate the current theoretical and empirical uncertainties relating to properties of the intracluster medium. Relative to the standard model, their angular power spectra differ by approximately 50% (TSZ), 20% (KSZ), and 40% (SZ at 148 GHz) for l=3000, sigma_8=0.8, and homogeneous reionization at z=10. The angular power spectrum decreases in amplitude as gas mass and binding energy is removed through star formation, and as gas is pushed out to larger radii by energetic feedback. With nonthermal pressure support, less pressure is required to maintain hydrostatic equilibrium, thus reducing the thermal contribution to the SZ power. We also calculate the SZ templates as a function of sigma_8 and quantify this dependence. Assuming C_l is proprotional to (sigma_8/0.8)^alpha, the effective scaling index ranges from 7<alpha_tsz<9, 4.5<alpha_ksz<5.5, and 6.5<alpha_sz(148 GHz)<8 at l=3000 for 0.6<sigma_8<1. The template spectra are publicly available and can be used when fitting for the SZ contribution to the cosmic microwave background on arcminute scales. Comment: 14 pages, 10 figures, to be submitted to ApJ
    The Astrophysical Journal 06/2010; · 6.73 Impact Factor
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    ABSTRACT: The deposition of mechanical feedback from a supermassive black hole (SMBH) in an active galactic nucleus (AGN) into the surrounding galaxy occurs via broad-line winds which must carry mass and radial momentum as well as energy. The effect can be summarized by the dimensionless parameter $\eta=dot{M_outflow}/dot{M_accretion}= (2 \epsilon_w c^2)/v_w^2$ where ($\epslion_w \equiv dot{E}_w/(dot{M_accretion} c^2)$) is the efficiency by which accreted matter is turned into wind energy in the disc surrounding the central SMBH. The outflowing mass and omentum are proportional to $\eta$, and many prior treatments have essentially assumed that $\eta=0$. We perform one- and two-dimensional simulations and find that the growth of the central SMBH is very sensitive to the inclusion of the mass and momentum driving but is insensitive to the assumed mechanical efficiency. For example in representative calculations, the omission of momentum and mass feedback leads to an hundred fold increase in the mass of the SMBH to over $10^{10} \Msun$. When allowance is made for momentum driving, the final SMBH mass is much lower and the wind efficiencies which lead to the most observationally acceptable results are relatively low with $\epsilon_w \lesssim 10^{-4}$. Comment: 10 pages, 8 figures, resubmitted to ApJ, added references
    04/2010;
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    L. Ciotti, J. P. Ostriker, D. Proga
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    ABSTRACT: We find, from high-resolution hydro simulations, that winds from AGN effectively heat the inner parts (~100 pc) of elliptical galaxies, reducing infall to the central SMBH; and radiative (photoionization and X-ray) heating reduces cooling flows at the kpc scale. Including both types of feedback with (peak) efficiencies of 3 10^{-4} < epsilon_mech < 10^{-3} and of epsilon_rad ~10^{-1.3} respectively, produces systems having duty-cycles, central SMBH masses, X-ray luminosities, optical light profiles, and E+A spectra in accord with the broad suite of modern observations of massive elliptical systems. Our main conclusion is that mechanical feedback (including all three of energy, momentum and mass) is necessary but the efficiency, based on several independent arguments must be a factor of 10 lower than is commonly assumed. Bursts are frequent at z>1 and decline in frequency towards the present epoch as energy and metal rich gas are expelled from the galaxies into the surrounding medium. For a representative galaxy of final stellar mass ~3 10^{11} Msun, roughly 3 10^{10} Msun of recycled gas has been added to the ISM since z~2 and, of that, roughly 63% has been expelled from the galaxy, 19% has been converted into new metal rich stars in the central few hundred parsecs, and 2% has been added to the central SMBH, with the remaining 16% in the form hot X-ray emitting ISM. The bursts occupy a total time of ~170 Myr, which is roughly 1.4% of the available time. Of this time, the central SMBH would be seen as an UV or optical source for ~45% and ~71$% of the time, respectively. Restricting to the last 8.5 Gyr, the burst occupy ~44 Myr, corresponding to a fiducial duty-cycle of ~5 10^{-3}. Comment: 41 pages, 11 figures (bitmapped, low-quality), ApJ accepted
    The Astrophysical Journal 03/2010; · 6.73 Impact Factor
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    C. N. Lackner, J. P. Ostriker
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    ABSTRACT: We examine two extreme models for the build-up of the stellar component of luminous elliptical galaxies. In one case, we assume the build-up of stars is dissipational, with centrally accreted gas radiating away its orbital and thermal energy; the dark matter (DM) halo will undergo adiabatic contraction and the central DM density profile will steepen. For the second model, we assume the central galaxy is assembled by a series of dissipationless mergers of stellar clumps that have formed far from the nascent galaxy. In order to be accreted, these clumps lose their orbital energy to the DM halo via dynamical friction, thereby heating the central DM and smoothing the DM density cusp. The central DM density profiles differ drastically between these models. For the isolated elliptical galaxy, NGC 4494, the central DM densities follow the power laws r –0.2 and r –1.7 for the dissipational and dissipationless models, respectively. By matching the dissipational and dissipationless models to observations of the stellar component of elliptical galaxies, we examine the relative contributions of dissipational and dissipationless mergers to the formation of elliptical galaxies and look for observational tests that will distinguish between these models. Comparisons to strong lensing brightest cluster galaxies yield median (M */L) B ratios of 2.1 ± 0.8 and 5.2 ± 1.7 at z 0.39 for the dissipational and dissipationless models, respectively. For NGC 4494, the best-fit dissipational and dissipationless models have (M */L) B = 2.97 and 3.96. Comparisons to expected stellar mass-to-light ratios from passive evolution and population syntheses appear to rule out a purely dissipational formation mechanism for the central stellar regions of giant elliptical galaxies.
    The Astrophysical Journal 02/2010; 712(1):88. · 6.73 Impact Factor
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    ABSTRACT: Both radiative and mechanical feedback from active galactic nuclei have been found to be important for the evolution of elliptical galaxies. We compute how a shock may be driven from a central black hole into the gaseous envelope of an elliptical galaxy by such feedback (in the form of nuclear winds) using high resolution one-dimensional hydrodynamic simulations. We calculate the synchrotron emission from the electron cosmic rays accelerated by the shocks (not the jets) in the central part of elliptical galaxies, and we also study the synchrotron spectrum's evolution using the standard diffusive shock acceleration mechanism, which is routinely applied to supernova remnants. We find quantitative consistency between the synchrotron radio emission produced via this mechanism with extant observations of elliptical galaxies which are undergoing outbursts. Additionally, we also find that synchrotron optical and X-ray emission can co-exist inside elliptical galaxies during a specific evolutionary phase subsequent to central outbursts. In fact, our calculations predict a peak synchrotron luminosity of ~1.3 × 106 L ☉ at the frequency 5 GHz (radio band), of ~1.1 × 106 L ☉ at 4.3 × 1014 Hz (corresponding to the absolute magnitude –10.4 in R band), and of ~1.5 × 107 L ☉ at 2.4 × 1017 Hz (soft X-ray, 0.5-2.0 keV band).
    The Astrophysical Journal 02/2010; 711(1):125. · 6.73 Impact Factor
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    ABSTRACT: We create realistic, full-sky, half-arcminute resolution simulations of the microwave sky matched to the most recent astrophysical observations. The primary purpose of these simulations is to test the data reduction pipeline for the Atacama Cosmology Telescope (ACT) experiment; however, we have widened the frequency coverage beyond the ACT bands and utilized the easily accessible HEALPix map format to make these simulations applicable to other current and near future microwave background experiments. Some of the novel features of these simulations are that the radio and infrared galaxy populations are correlated with the galaxy cluster and group populations, the primordial microwave background is lensed by the dark matter structure in the simulation via a ray-tracing code, the contribution to the thermal and kinetic Sunyaev-Zel'dovich (SZ) signals from galaxy clusters, groups, and the intergalactic medium has been included, and the gas prescription to model the SZ signals has been refined to match the most recent X-ray observations. The cosmology adopted in these simulations is also consistent with the WMAP 5-year parameter measurements. From these simulations we find a slope for the Y 200-M 200 relation that is only slightly steeper than self-similar, with an intrinsic scatter in the relation of ~14%. Regarding the contamination of cluster SZ flux by radio galaxies, we find for 148 GHz (90 GHz) only 3% (4%) of halos have their SZ decrements contaminated at a level of 20% or more. We find the contamination levels higher for infrared galaxies. However, at 90 GHz, less than 20% of clusters with M 200 > 2.5 × 1014 M ☉ and z < 1.2 have their SZ decrements filled in at a level of 20% or more. At 148 GHz, less than 20% of clusters with M 200 > 2.5 × 1014 M ☉ and z < 0.8 have their SZ decrements filled in at a level of 50% or larger. Our models also suggest that a population of very high flux infrared galaxies, which are likely lensed sources, contribute most to the SZ contamination of very massive clusters at 90 and 148 GHz. These simulations are publicly available and should serve as a useful tool for microwave surveys to cross-check SZ cluster detection, power spectrum, and cross-correlation analyses.
    The Astrophysical Journal 01/2010; 709(2):920. · 6.73 Impact Factor
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    ABSTRACT: We find that the amount and nature of the assumed ionizing background can strongly affect galaxy formation and evolution. Galaxy evolution simulations typically incorporate an ultraviolet background which falls off rapidly above z=3; e.g., that of Haardt & Madau (1996). However, this decline may be too steep to fit the WMAP constraints on electron scattering optical depth or observations of intermediate redshift (z ~ 2-4) Ly-alpha forest transmission. As an alternative, we present simulations of the cosmological formation of individual galaxies with UV backgrounds that decline more slowly at high redshift: both a simple intensity rescaling and the background recently derived by Faucher-Giguere (2009), which softens the spectrum at higher redshifts. We also test an approximation of the X-ray background with a similar z-dependence. We find for the test galaxies that an increase in either the intensity or hardness of ionizing radiation generically pushes star formation towards lower redshifts: although overall star formation in the simulation boxes is reduced by 10-25%, the galaxies show a factor of ~2 increase in the fraction of stars within a 30 kpc radius that are formed after z=1. Other effects include late gas inflows enhanced up to 30 times, stellar half-mass radii decreased by up to 30%, central velocity dispersions increased up to 40%, and a strong reduction in substructure. The magnitude of the effects depends on the environmental/accretion properties of the particular galaxy. Comment: 10 emulateapj pages, 10 figures; accepted by ApJ
    The Astrophysical Journal 09/2009; · 6.73 Impact Factor
  • Jeremiah P Ostriker, Charlotte Kuh
    Science 06/2009; 324(5931):1141. · 31.20 Impact Factor
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    Min-Su Shin, Jeremiah P. Ostriker, Luca Ciotti
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    ABSTRACT: By using high-resolution 1D hydrodynamical simulations, we investigate the effects of purely mechanical feedback from super massive black holes (SMBHs) in the evolution of elliptical galaxies for a broad range of feedback efficiencies and compare the results to four major observational constraints. In particular, we focus on 1) the central black hole to stellar mass ratio of the host galaxy, 2) the lifetime of the luminous quasar phase, 3) the mass of stars formed in the host galaxy within the last Gyr, and 4) the X-ray luminosity of the hot diffuse gas. As a result, we try to pin down the most successful range of mechanical feedback efficiencies. We find that while low feedback efficiencies result in too much growth of the SMBH, high efficiencies totally blow out the hot interstellar gas, and the models are characterized by very low thermal X-ray luminosity well below the observed range. The net lifetime of the quasar phase is strongly coupled to the mass ratio between SMBH and its host galaxy, while the X-ray luminosity is generally correlated to the recent star formation within the last Gyr. When considering the popularly adopted model of the constant feedback efficiency, the feedback energy deposited into the ambient medium should be more than 0.01% of the SMBH accretion energy to be consistent with the SMBH mass to stellar mass ratio in the local universe. Yet, the X-ray luminosity of the hot gas favors about 0.005% of the accretion energy as the mechanical AGN feedback energy. We conclude that the purely mechanical feedback mode is unlikely to be simultaneously compatible with all four observable tests, even allowing a broad range of feedback efficiencies, and that including both radiative and mechanical feedback together may be a solution to comply the observational constraints. [abridged]
    The Astrophysical Journal 05/2009; 711(1). · 6.73 Impact Factor
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    Paul Bode, Jeremiah P. Ostriker, Alexey Vikhlinin
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    ABSTRACT: The state of the hot gas in clusters of galaxies is investigated with a set of model clusters, created by assuming a polytropic equation of state (Gamma=1.2) and hydrostatic equilibrium inside gravitational potential wells drawn from a dark matter simulation. Star formation, energy input, and nonthermal pressure support are included. To match the gas fractions seen in non-radiative hydrodynamical simulations, roughly 5% of the binding energy of the dark matter must be transferred to the gas during cluster formation; the presence of nonthermal pressure support increases this value. In order to match X-ray observations, scale-free behavior must be broken. This can be due to either variation of the efficiency of star formation with cluster mass M_500, or the input of additional energy proportional to the formed stellar mass M_F. These two processes have similar effects on X-ray scalings. If 9% of the gas is converted into stars, independent of cluster mass, then feedback energy input of 1.2e-5*M_Fc^2 (or ~1.0 keV per particle) is required to match observed clusters. Alternatively, if the stellar mass fraction varies as M_500^-0.26 then a lower feedback of 4e-6*M_Fc^2 is needed, and if the stellar fraction varies as steeply as M_500^-0.49 then no additional feedback is necessary. The model clusters reproduce the observed trends of gas temperature and gas mass fraction with cluster mass, as well as observed entropy and pressure profiles; thus they provide a calibrated basis with which to interpret upcoming SZ surveys. One consequence of the increased gas energy is that the baryon fraction inside the virial radius is less than roughly 90% of the cosmic mean, even for the most massive clusters. Comment: Accepted by ApJ; 28 pages, 12 figures
    The Astrophysical Journal 05/2009; · 6.73 Impact Factor
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    S. Pellegrini, L. Ciotti, J.P. Ostriker
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    ABSTRACT: The centers of elliptical galaxies host supermassive black holes that significantly affect the surrounding interstellar medium through feedback resulting from the accretion process. The evolution of this gas and of the nuclear emission during the galaxies’ lifetime has been studied recently with high-resolution hydrodynamical simulations. These included gas cooling and heating specific for an average AGN spectral energy distribution, a radiative efficiency declining at low mass accretion rates, and mechanical coupling between the hot gas and AGN winds. Here, we present a short summary of the observational properties resulting from the simulations, focussing on (1) the nuclear luminosity; (2) the global luminosity and temperature of the hot gas; (3) its temperature profile and X-ray brightness profile. These properties are compared with those of galaxies of the local universe, pointing out the successes of the adopted feedback and the needs for new input in the simulations.
    Advances in Space Research 05/2009; · 1.18 Impact Factor
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    ABSTRACT: This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11,663 deg^2 of imaging data, with most of the ~2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry on a 120° long, 2°.5 wide stripe along the celestial equator in the Southern Galactic Cap, with some regions covered by as many as 90 individual imaging runs. We include a co-addition of the best of these data, going roughly 2 mag fainter than the main survey over 250 deg^2. The survey has completed spectroscopy over 9380 deg^2; the spectroscopy is now complete over a large contiguous area of the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog, reducing the rms statistical errors at the bright end to 45 milliarcseconds per coordinate. We further quantify a systematic error in bright galaxy photometry due to poor sky determination; this problem is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities.
    The Astrophysical Journal Supplement Series 05/2009; 182(2):543. · 16.24 Impact Factor
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    Yen-Ting Lin, Jeremiah P. Ostriker, Christopher J. Miller
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    ABSTRACT: A novel statistic is proposed to examine the hypothesis that all cluster galaxies are drawn from the same luminosity distribution (LD). In such a "statistical model" of galaxy LD, the brightest cluster galaxies (BCGs) are simply the statistical extreme of the galaxy population. Using a large sample of nearby clusters, we show that BCGs in high luminosity clusters (e.g., L_tot > 4x10^11 L_sun) are unlikely (probability <3x10^-4) to be drawn from the LD defined by all red cluster galaxies more luminous than M_r=-20. On the other hand, BCGs in less luminous clusters are consistent with being the statistical extreme. Applying our method to the second brightest galaxies, we show that they are consistent with being the statistical extreme, which implies that the BCGs are also distinct from non-BCG luminous, red, cluster galaxies. We point out some issues with the interpretation of the classical tests proposed by Tremaine & Richstone (1977) that are designed to examine the statistical nature of BCGs, investigate the robustness of both our statistical test and those of TR against difficulties in photometry of galaxies of large angular size, and discuss the implication of our findings on surveys that use the luminous red galaxies to measure the baryon acoustic oscillation features in the galaxy power spectrum. Comment: 12 pages, 8 figures, 4 tables; published in ApJ
    The Astrophysical Journal 04/2009; · 6.73 Impact Factor
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    ABSTRACT: Great strides have been made in the last two decades in determining how galaxies evolve from their initial dark matter seeds to the complex structures we observe at z=0. The role of mergers has been documented through both observations and simulations, numerous satellites that may represent these initial dark matter seeds have been discovered in the Local Group, high redshift galaxies have been revealed with monstrous star formation rates, and the gaseous cosmic web has been mapped through absorption line experiments. Despite these efforts, the dark matter simulations that include baryons are still unable to accurately reproduce galaxies. One of the major problems is our incomplete understanding of how a galaxy accretes its baryons and subsequently forms stars. Galaxy formation simulations have been unable to accurately represent the required gas physics on cosmological timescales, and observations have only just begun to detect the star formation fuel over a range of redshifts and environments. How galaxies obtain gas and subsequently form stars is a major unsolved, yet tractable problem in contemporary extragalactic astrophysics. In this paper we outline how progress can be made in this area in the next decade.
    03/2009;
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    Peter H. Johansson, Thorsten Naab, Jeremiah P. Ostriker
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    ABSTRACT: We study the thermal formation history of four simulated galaxies that were shown in Naab et al. (2007) to reproduce a number of observed properties of elliptical galaxies. The temperature of the gas in the galaxies is steadily increasing with decreasing redshift, although much of the gas has a cooling time shorter than the Hubble time. The gas is being heated and kept hot by gravitational heating processes through the release of potential energy from infalling stellar clumps. The energy is dissipated in supersonic collisions of infalling gas lumps with the ambient gas and through the dynamical capturing of satellite systems causing gravitational wakes that transfer energy to the surrounding gas. Furthermore dynamical friction from the infalling clumps pushes out dark matter, lowering the central dark matter density by up to a factor of two from z=3 to z=0. In galaxies in which the late formation history (z<2) is dominated by minor merging and accretion the energy released (E~5x10^{59} ergs) from gravitational feedback is sufficient to form red and dead elliptical galaxies by z~1 even in the absence of supernova and AGN feedback.
    The Astrophysical Journal 03/2009; 697(1). · 6.73 Impact Factor
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    Thorsten Naab, Peter H. Johansson, Jeremiah P. Ostriker
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    ABSTRACT: Using a high resolution hydrodynamical cosmological simulation of the formation of a massive spheroidal galaxy we show that elliptical galaxies can be very compact and massive at high redshift in agreement with recent observations. Accretion of stripped in-falling stellar material increases the size of the system with time and the central concentration is reduced by dynamical friction of the surviving stellar cores. In a specific case of a spheroidal galaxy with a final stellar mass of $1.5 \times 10^{11} M_{\odot}$ we find that the effective radius $r_e$ increases from $0.7 \pm 0.2 \rm kpc$ at z = 3 to $r_e = 2.4 \pm 0.4 \rm kpc$ at z = 0 with a concomitant decrease in the effective density of an order of magnitude and a decrease of the central velocity dispersion by approximately 20% over this time interval. A simple argument based on the virial theorem shows that during the accretion of weakly bound material (minor mergers) the radius can increase as the square of the mass in contrast to the usual linear rate of increase for major mergers. By undergoing minor mergers compact high redshift spheroids can evolve into present-day systems with sizes and concentrations similar to observed local ellipticals. This indicates that minor mergers may be the main driver for the late evolution of sizes and densities of early-type galaxies.
    The Astrophysical Journal 03/2009; 699. · 6.73 Impact Factor
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    ABSTRACT: We use an Eulerian hydrodynamic cosmological simulation to model the Lyα forest in a spatially flat, COBE-normalized, cold dark matter model with) Ω = 0.4. We find that the intergalactic, photoionized gas is predicted to collapse into sheetlike and filamentary structures which give rise to absorption lines having characteristics similar to the observed Lyα forest. A typical filament is ~500 h–1 kpc long with thickness ~50 h–1 kpc (in proper units), and baryonic mass ~ 1010 h−1 M. In comparison our cell size is (2.5, 9) h−1 kpc in the two simulations we perform, with true resolution perhaps a factor of 2.5 worse than this. The gas temperature is in the range 104-105 K, and it increases with time as structures with larger velocities collapse gravitationally. We show that the predicted distributions of column densities, b-parameters, and equivalent widths of the Lyα forest clouds agree reasonably with observations, and that their evolution is consistent with the observed evolution, if the ionizing background has an approximately constant intensity between z = 2 and z = 4. A new method of identifying lines as contiguous regions in the spectrum below a fixed flux threshold is suggested to analyze the absorption lines, given that the Lyα spectra arise from a continuous density field of neutral hydrogen rather than discrete clouds. We also predict the distribution of transmitted flux and its correlation along a spectrum and on parallel spectra, and the He ii flux decrement as a function of redshift. We predict a correlation length of ~80 h−1 kpc perpendicular to the line of sight for features in the Lyα forest. In order to reproduce the observed number of lines and average flux transmission, the baryon content of the clouds may need to be significantly higher than in previous models because of the low densities and large volume-filling factors we predict. If the background intensity JH I is at least that predicted from the observed quasars, Ωb needs to be as high as ~0.25 h−2. The model also predicts that most of the baryons at z > 2 are in Lyα clouds, and that the rate at which the baryons move to more overdense regions is slow. A large fraction of the baryons which are not observed at present in galaxies might be intergalactic gas in the currently collapsing structures, with T ~ 105–106 K. All our results on the statistical properties of the simulated spectra are predictions that can be directly tested by applying the same methods to observed spectra. We are making the simulated spectra electronically available.
    The Astrophysical Journal 01/2009; 471(2):582. · 6.73 Impact Factor
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    ABSTRACT: We have simulated the formation of an X-ray cluster in a cold dark matter universe using 12 different codes. The codes span the range of numerical techniques and implementations currently in use, including smoothed particle hydrodynamics (SPH) and grid methods with fixed, deformable, or multilevel meshes. The goal of this comparison is to assess the reliability of cosmological gasdynamical simulations of clusters in the simplest astrophysically relevant case, that in which the gas is assumed to be nonradiative. We compare images of the cluster at different epochs, global properties such as mass, temperature and X-ray luminosity, and radial profiles of various dynamical and thermodynamical quantities. On the whole, the agreement among the various simulations is gratifying, although a number of discrepancies exist. Agreement is best for properties of the dark matter and worst for the total X-ray luminosity. Even in this case, simulations that adequately resolve the core radius of the gas distribution predict total X-ray luminosities that agree to within a factor of 2. Other quantities are reproduced to much higher accuracy. For example, the temperature and gas mass fraction within the virial radius agree to within about 10%, and the ratio of specific dark matter kinetic to gas thermal energies agree to within about 5%. Various factors, including differences in the internal timing of the simulations, contribute to the spread in calculated cluster properties. Based on the overall consistency of results, we discuss a number of general properties of the cluster we have modeled.
    The Astrophysical Journal 01/2009; 525(2):554. · 6.73 Impact Factor
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    L. Ciotti, J. P. Ostriker, D. Proga
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    ABSTRACT: The importance of the radiative feedback from SMBHs at the centers of elliptical galaxies is not in doubt, given the well established relations among electromagnetic output, black hole mass and galaxy optical luminosity. In addition, feedback due to mechanical and thermal deposition of energy from jets and winds emitted by the accretion disk around the central SMBH is also expected to occur. In this paper we improve and extend the accretion and feedback physics explored in our previous papers to include also a physically motivated mechanical feedback. We study the evolution of an isolated elliptical galaxy with the aid of a high-resolution 1-D hydrodynamical code, where the cooling and heating functions include photoionization and Compton effects, and restricting to models which include only radiative or only mechanical feedback. We confirm that for Eddington ratios above 0.01 both the accretion and radiative output are forced by feedback effects to be in burst mode, so that strong intermittencies are expected at early times, while at low redshift the explored models are characterized by smooth, very sub-Eddington mass accretion rates punctuated by rare outbursts. However, the explored models always fail some observational tests. If we assume the high mechanical efficiency of 10^{-2.3}, we find that most of the gas is ejected from the galaxy, the resulting X-ray luminosity is far less than is typically observed and little SMBH growth occurs. But models with low enough mechanical efficiency to accomodate satisfactory SMBH growth tend to allow too strong cooling flows and leave galaxies at z=0 with E+A spectra more frequently than is observed. We conclude that both types of feedback are required. Models with combined feedback are explored in a forthcoming paper [abridged] Comment: 42 pages, 4 figures (low resolution), ApJ accepted
    The Astrophysical Journal 01/2009; · 6.73 Impact Factor
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    ABSTRACT: What breakthrough advances will petascale computing bring to various science and engineering fields? Experts in everything from astronomy to seismology envision the opportunities ahead and the impact they'll have on advancing our understanding of the world.
    Computing in Science and Engineering 01/2009; 11(5):28-37. · 1.73 Impact Factor

Publication Stats

20k Citations
2,096.19 Total Impact Points

Institutions

  • 1975–2014
    • Princeton University
      • • Department of Astrophysical Sciences
      • • Department of Physics
      Princeton, New Jersey, United States
  • 2012
    • West Virginia University
      Morgantown, West Virginia, United States
  • 2009
    • California Institute of Technology
      • Department of Astronomy
      Pasadena, California, United States
    • Pontifical Catholic University of Chile
      • Departamento de Astronomía y Astrofísica
      CiudadSantiago, Santiago, Chile
    • University of Bologna
      • Department of Physics and Astronomy DIFA
      Bolonia, Emilia-Romagna, Italy
  • 2008
    • Chinese Academy of Sciences
      • Shanghai Astronomical Observatory
      Peping, Beijing, China
  • 1977–2008
    • University of Cambridge
      • Institute of Astronomy
      Cambridge, ENG, United Kingdom
  • 2007
    • Los Alamos National Laboratory
      • Theoretical Division
      Los Alamos, California, United States
  • 1993–2007
    • TRI/Princeton
      Princeton, New Jersey, United States
  • 2003
    • Università degli Studi di Siena
      Siena, Tuscany, Italy
  • 2002
    • Cancer Research UK Cambridge Institute
      Cambridge, England, United Kingdom
    • Fermi National Accelerator Laboratory (Fermilab)
      Batavia, Illinois, United States
  • 1997–2000
    • The Astronomical Observatory of Brera
      Merate, Lombardy, Italy
  • 1998
    • The University of Tokyo
      Tōkyō, Japan
    • Seoul National University
      • Department of Physics and Astronomy
      Sŏul, Seoul, South Korea
  • 1996
    • University of Washington Seattle
      • Department of Astronomy
      Seattle, Washington, United States
  • 1995
    • University of Illinois, Urbana-Champaign
      • Department of Astronomy
      Urbana, IL, United States
  • 1974
    • Tel Aviv University
      Tell Afif, Tel Aviv, Israel