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1

ISO proves that intergalactic space is dusty  

NASA Astrophysics Data System (ADS)

In the past, astronomers have considered intergalactic space to be extremely clean. Except in the vast concentrations of stars, gas and dust that make up the galaxies themselves, the Universe was supposed to be filled only by very thin traces of invisible gas. ISO's detection of dust means that the Universe is less transparent than astronomers have assumed. Their cosmic window-pane is slightly dirty and large-scale inferences based on the brightnesses of distant galaxies and quasars may be affected. Emissions from the intergalactic dust were picked up by the photometer ISOPHOT. A team of German, British, Spanish and Danish astronomers contributed this versatile set of detectors to ISO. The leader of the ISOPHOT team is Dietrich Lemke of the Max-Planck Institut fr Astronomie (MPIA) in Heidelberg, Germany. "ISOPHOT in ISO is the only instrument in existence capable of making this detection" Lemke says. "The intergalactic dust is so cold that we need a very cold telescope to detect it. The strongest emissions from the dust are at a wavelength of 0.1-0.2 millimetre, which cannot be well observed from the Earth. ISO provides telescope in space cooled by superfluid helium to within 2 degrees of absolute zero. ISOPHOT is the instrument on ISO that measures infrared intensities at the longest wavelengths, up to 0.2 millimetre." ISOPHOT's advantages made finding the intergalactic dust possible, but not easy. The observations pushed instrumental sensitivity to the limit, and emissions from cold dust clouds in the Milky Way Galaxy confused the picture. The signal of intergalactic dust emerged clearly only after extensive data analysis. Cold dust in a hot cluster Our home Galaxy, the Milky Way, belongs to a very small group of galaxies. Intergalactic dust may very well be present nearby, but it is likely to be sparse and scattered. A team of astronomers, from MPIA Heidelberg and Helsinki Observatory, hoped that the intergalactic dust might be easier to recognise in a large cluster of galaxies. They chose the Coma Cluster, which fills an area of the sky twice as wide as the Full Moon even though it is about 450 million light-years away. ISO scanned the Coma Cluster twice, along different cross-sections, measuring with ISOPHOT its emissions of long-wavelength infrared rays. The hunch of the German-Finnish team turned out to be correct. Emissions indicating the presence of intergalactic dust were much stronger towards the crowded centre of the cluster than at the edges. The results on the Coma Cluster obtained with ISO seem to contradict, at first sight, observations of the same cluster by another space observatory built in Europe. The German-US-UK Rosat satellite for X-ray astronomy has charted X-rays coming from very hot gas between the galaxies, and concentrated towards the centre of the Coma Cluster. The intergalactic gas detected by Rosat has a temperature of 80 million degrees, far hotter even than the core of the Sun. "The dust particles are at the very cold end of the temperature scale," says Kalevi Mattila of Helsinki Observatory. "ISOPHOT allows us to measure temperatures for them, in the range minus 220 to minus 250 degrees Celsius." How can cold dust at minus 250 degrees survive within a very hot gas? The gas is extremely tenuous, so it cannot simply warm the grains of dust like a hair-drier. Instead the hot gas subjects the dust to impacts by energetic atomic particles which knock atoms out of it, and so gradually erode the dust grains. Calculations suggest that the hot gas will destroy the cold dust in about 100 million years. Although that is very slow by human standards, it represents only one-hundredth of the age of the galaxies. Experts therefore have to consider where fresh supplies of intergalactic dust come from. Rosat astronomers found that the Coma Cluster is not spherical, which would be the shape expected in an isolated cluster. By X-rays, the cloud of hot intergalactic gas is seen to be egg-shaped. The same shape is apparent in the intergalactic dust cloud observed by IS

1997-11-01

2

Transonic galactic outflows and their influences to the chemical evolution of galaxies and intergalactic space  

NASA Astrophysics Data System (ADS)

Galactic winds are widely recognized as important ingredients in galaxy evolution, and they impact the chemical enrichment of galaxies and the intergalactic medium. We investigate the acceleration process of isothermal, spherically symmetric steady galactic outflows in an appropriate galactic gravitational potential applying the transonic analysis which is the well-known approach for the solar wind. The results show that the transonic solutions of the galactic winds critically depend upon the mass distribution in a galaxy such as the dark matter halo (DMH) and the central super massive black hole (SMBH). We discover the existence of two types of transonic solutions in the gravity from the combination of DMH and SMBH. The first one is accelerated near the SMBH which is similar to the Parker solution, and the other is slowly accelerated over the entire region of DMH. These two transonic solutions have different mass fluxes and starting points. Therefore, they have different influences to the chemical evolution of galaxies and intergalactic space. We have found that the mass fluxes of two transonic solutions are considerably different by several orders of magnitude in spite of the same mass distribution. This result indicates that mass flux is very sensitive not only to the mass distribution but also to the chosen transonic solution.

Igarashi, Asuka; Mori, Masao; Nitta, Shin-ya

2014-05-01

3

Simulating intergalactic quasar scintillation  

NASA Astrophysics Data System (ADS)

Intergalactic scintillation of distant quasars is sensitive to free electrons and therefore complements Ly? absorption-line experiments probing the neutral intergalactic medium (IGM). We present a new scheme to compute IGM refractive scintillation effects on distant sources in combination with adaptive mesh refinement cosmological simulations. First, we validate our model by reproducing the well-known interstellar scintillation (ISS) of Galactic sources. The simulated cosmic density field is then used to infer the statistical properties of intergalactic scintillation. Contrary to previous claims, we find that the scattering measure of the simulated IGM at z < 2 is = 3.879, i.e. almost 40 times larger than that for the usually assumed smooth IGM. This yields an average modulation index ranging from 0.01 (?s = 5 GHz) up to 0.2 (?s = 50 GHz); above ?s ? 30 GHz the IGM contribution dominates over ISS modulation. We compare our model with data from a 0.3 ? z ? 2 quasar sample observed at ?obs = 8.4 GHz. For this high-frequency (10.92 ? ?s ? 25.2), high-galactic-latitude sample ISS is negligible, and IGM scintillation can reproduce the observed modulation with a 4 per cent accuracy, without invoking intrinsic source variability. We conclude by discussing the possibility of using IGM scintillation as a tool to pinpoint the presence of intervening high-z groups/clusters along the line of sight, thus making it a probe suitably complementing Sunyaev-Zel'dovich data recently obtained by Planck.

Pallottini, A.; Ferrara, A.; Evoli, C.

2013-10-01

4

Ten More New Sightlines for the Study of Intergalactic Helium, and Hundreds of Far-Ultraviolet-Bright Quasars, from the Sloan Digital Sky Survey, Galaxy Evolution Explorer, and Hubble Space Telescope  

NASA Astrophysics Data System (ADS)

Absorption along quasar sightlines remains among the most sensitive direct measures of He II reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the He II Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean He II quasars, exploiting Sloan Digital Sky Survey (SDSS) quasar samples, broadband ultraviolet (UV) imaging from Galaxy Evolution Explorer (GALEX), and high-yield UV spectroscopic confirmations from Hubble Space Telescope (HST). Here we markedly expand this approach by cross-correlating SDSS DR7 and GALEX GR4+5 to catalog 428 SDSS and 165 other quasars with z > 2.78 having likely (~70%) GALEX detections, suggesting they are bright into the far-UV. Reconnaissance HST Cycle 16 Supplemental prism data for 29 of these new quasar-GALEX matches spectroscopically confirm 17 as indeed far-UV bright. At least 10 of these confirmations have clean sightlines all the way down to He II Ly?, substantially expanding the number of known clean He II quasars, and reaffirming the order of magnitude enhanced efficiency of our selection technique. Combined confirmations from this and our past programs yield more than 20 He II quasars, quintupling the sample. These provide substantial progress toward a sample of He II quasar sightlines large enough, and spanning a sufficient redshift range, to enable statistical IGM studies that may avoid individual object peculiarity and sightline variance. Our expanded catalog of hundreds of high-likelihood far-UV-bright QSOs additionally will be useful for understanding the extreme-UV properties of the quasars themselves. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Syphers, David; Anderson, Scott F.; Zheng, Wei; Haggard, Daryl; Meiksin, Avery; Schneider, Donald P.; York, Donald G.

2009-11-01

5

TEN MORE NEW SIGHTLINES FOR THE STUDY OF INTERGALACTIC HELIUM, AND HUNDREDS OF FAR-ULTRAVIOLET-BRIGHT QUASARS, FROM THE SLOAN DIGITAL SKY SURVEY, GALAXY EVOLUTION EXPLORER, AND HUBBLE SPACE TELESCOPE  

SciTech Connect

Absorption along quasar sightlines remains among the most sensitive direct measures of He II reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the He II Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean He II quasars, exploiting Sloan Digital Sky Survey (SDSS) quasar samples, broadband ultraviolet (UV) imaging from Galaxy Evolution Explorer (GALEX), and high-yield UV spectroscopic confirmations from Hubble Space Telescope (HST). Here we markedly expand this approach by cross-correlating SDSS DR7 and GALEX GR4+5 to catalog 428 SDSS and 165 other quasars with z > 2.78 having likely ({approx}70%) GALEX detections, suggesting they are bright into the far-UV. Reconnaissance HST Cycle 16 Supplemental prism data for 29 of these new quasar-GALEX matches spectroscopically confirm 17 as indeed far-UV bright. At least 10 of these confirmations have clean sightlines all the way down to He II Ly{alpha}, substantially expanding the number of known clean He II quasars, and reaffirming the order of magnitude enhanced efficiency of our selection technique. Combined confirmations from this and our past programs yield more than 20 He II quasars, quintupling the sample. These provide substantial progress toward a sample of He II quasar sightlines large enough, and spanning a sufficient redshift range, to enable statistical IGM studies that may avoid individual object peculiarity and sightline variance. Our expanded catalog of hundreds of high-likelihood far-UV-bright QSOs additionally will be useful for understanding the extreme-UV properties of the quasars themselves.

Syphers, David [Physics Department, University of Washington, Seattle, WA 98195 (United States); Anderson, Scott F.; Haggard, Daryl [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Zheng Wei [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Meiksin, Avery [Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Schneider, Donald P. [Pennsylvania State University, Department of Physics and Astronomy, 525 Davey Lab, University Park, PA 16802 (United States); York, Donald G. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)], E-mail: dsyphers@phys.washington.edu, E-mail: anderson@astro.washington.edu, E-mail: zheng@pha.jhu.edu

2009-11-01

6

The physics and early history of the intergalactic medium  

NASA Astrophysics Data System (ADS)

The intergalactic medium—the cosmic gas that fills the great spaces between the galaxies—is affected by processes ranging from quantum fluctuations in the very early Universe to radiative emission from newly formed stars. This gives the intergalactic medium a dual role as a powerful probe both of fundamental physics and of astrophysics. The heading of fundamental physics includes conditions in the very early Universe and cosmological parameters that determine the age of the Universe and its matter content. The astrophysics refers to chapters of the long cosmic history of stars and galaxies that are being revealed through the effects of stellar feedback on the cosmic gas. This review describes the physics of the intergalactic medium, focusing on recent theoretical and observational developments in understanding early cosmic history. In particular, the earliest generation of stars is thought to have transformed the Universe from darkness to light and to have had an enormous impact on the intergalactic medium. Half a million years after the Big Bang the Universe was filled with atomic hydrogen. As gravity pulled gas clouds together, the first stars ignited and their radiation turned the surrounding atoms back into free electrons and ions. From the observed spectral absorption signatures of the gas between us and distant sources, we know that the process of reionization pervaded most of space a billion years after the Big Bang, so that only a small fraction of the primordial hydrogen atoms remained between galaxies. Knowing exactly when and how the reionization process happened is a primary goal of cosmologists, because this would tell us when the early stars and black holes formed and in what kinds of galaxies. The distribution and clustering of these galaxies is particularly interesting since it is driven by primordial density fluctuations in the dark matter. Cosmic reionization is beginning to be understood with the help of theoretical models and computer simulations. Numerical simulations of reionization are computationally challenging, as they require radiative transfer across large cosmological volumes as well as sufficiently high resolution to identify the sources of the ionizing radiation in the infant Universe. Rapid progress in our understanding is expected with additional observational input. A wide variety of instruments currently under design—including large-aperture infrared telescopes on the ground or in space (JWST), and low-frequency radio telescope arrays for the detection of redshifted 21 cm radiation—will probe the first sources of light during an epoch in cosmic history that has been largely unexplored so far. The new observations and the challenges for theoretical models and numerical simulations will motivate intense work in this field over the coming decade.

Barkana, Rennan; Loeb, Abraham

2007-04-01

7

The sources of intergalactic metals  

NASA Astrophysics Data System (ADS)

We study the clustering properties of metals in the intergalactic medium (IGM) as traced by 619 CIV and 81 SiIV absorption components with N>= 1012cm-2 and 316 MgII and 82 FeII absorption components with N>= 1011.5cm-2 in 19 high signal-to-noise ratio (60-100 pixel-1), high-resolution (R= 45000) quasar spectra. CIV and SiIV trace each other closely and their line-of-sight correlation functions ?(v) exhibit a steep decline at large separations and a flatter profile below ~150 km s-1, with a large overall bias. These features do not depend on absorber column densities, although there are hints that the overall amplitude of ?CIV (v) increases with time over the redshift range detected (1.5-3). Carrying out a detailed smoothed particle hydrodynamic simulation (2 × 3203, 57 Mpc3 comoving), we show that the CIV correlation function cannot be reproduced by models in which the IGM metallicity is constant or a local function of overdensity (Z~?2/3). However, the properties of ?CIV(v) are generally consistent with a model in which metals are confined within bubbles with a typical radius Rs about sources of mass >=Ms. We derive best-fitting values of Rs~ 2 comoving Mpc and Ms~ 1012Msolar at z= 3. Our lower-redshift (0.5-2) measurements of the MgII and FeII correlation functions also uncover a steep decline at large separations and a flatter profile at small separations, but the clustering is even higher than in the z= 1.5-3 measurements, and the turnover is shifted to somewhat smaller distances, ~75 km s-1. Again, these features do not change with column density, but there are hints that the amplitudes of ?MgII(v) and ?FeII(v) increase with time. We describe an analytic `bubble' model for these species, which come from regions that are too compact to be accurately simulated numerically, deriving best-fitting values of Rs~ 2.4 Mpc and Ms~ 1012Msolar. Equally good analytic fits to all four species are found in a similarly biased high-redshift enrichment model in which metals are placed within 2.4 comoving Mpc of Ms~ 3 × 109 sources at z= 7.5.

Scannapieco, E.; Pichon, C.; Aracil, B.; Petitjean, P.; Thacker, R. J.; Pogosyan, D.; Bergeron, J.; Couchman, H. M. P.

2006-01-01

8

Intergalactic Hydrogen Clouds at Low Redshift: Connections to Voids and Dwarf Galaxies.  

National Technical Information Service (NTIS)

We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Ly(alpha) clouds located along sightlines to four bright quasars passing through well-mapped ga...

J. M. Shull J. T. Stocke S. Penton

1996-01-01

9

Simulating the Effects of Intergalactic Gray Dust.  

PubMed

Using a high-resolution cosmological hydrodynamic simulation, we present a method to constrain extinction due to intergalactic gray dust based on the observed magnitudes of distant Type Ia supernovae. We apply several simple prescriptions to relate the intergalactic dust density to the gas density in the simulation, thereby obtaining dust extinctions that may be directly compared with the observed distribution of supernova magnitudes. Our analysis is sensitive to the spatial distribution of gray dust but is not dependent on its intrinsic properties, such as its opacity or grain size. We present an application of our technique to the supernova data of Perlmutter et al., who find that their high-redshift sample is approximately 0.2 mag fainter than the expectation for a nonaccelerating, low-density universe. We find that for gray dust to be responsible, it must be distributed quite smoothly (e.g., tracing intergalactic gas). More realistic dust distributions, such as dust tracing the metal density, are inconsistent with observations at the 1.5-2 sigma level. Upcoming observations and improved modeling of the dust distribution should lead to stronger constraints on intergalactic gray dust extinction. PMID:10813663

Croft; Davé; Hernquist; Katz

2000-05-10

10

Intergalactic absorption and blazar ?-ray spectra  

NASA Astrophysics Data System (ADS)

The distribution of TeV spectral slopes versus redshift for currently known TeV blazars (16 sources with z ? 0.21, and one with z > 0.25) is essentially a scatter plot with hardly any hint of a global trend. We suggest that this is the outcome of two combined effects of intergalactic ?? absorption, plus an inherent feature of the SSC (synchro-self-Compton) process of blazar emission. First, flux dimming introduces a bias that favors detection of progressively more flaring sources at higher redshifts. According to mainstream SSC models, more flaring source states imply sources with flatter TeV slopes. This results in a structured relation between intrinsic TeV slope and redshift. The second effect, spectral steepening by intergalactic absorption, affects sources progressively with distance and effectively wipes out the intrinsic slope-redshift correlation.

Persic, M.; de Angelis, A.

2008-05-01

11

Intergalactic Magnetic Fields, and Some Connections with Cosmic Rays  

NASA Astrophysics Data System (ADS)

An overview is presented of the methods of probing for the geometry, and strength of intergalactic magnetic fields. Recent results are briefly surveyed for galaxy halos, galaxy clusters, and the intergalactic medium on various scales, and some rele vant physical processes and radiation processes are mentioned, as well as the “coupling” between intergalactic magnetic fields and cosmic rays. The general trend of recent results indicates that, wherever we detect intergalactic hot gas and galaxies, we also find magnetic fields at levels of ˜ 10-7 G, or higher. The hitherto undetected, weaker fields in the ratified i.g.m. and in large intergalactic voids could be probed by both Faraday rotation, and possibly using very energetic CR nuclei (> 1020eV), and/or transient extragalactic ? ray bursts.

Kronberg, Philipp P.

1996-01-01

12

Constraints on dark matter from intergalactic radiation  

NASA Technical Reports Server (NTRS)

Several of the dark matter candidates that have been proposed are believed to be unstable to decay, which would contribute photons to the radiation field between galaxies. The main candidates of this type are light neutrinos and axions, primordial mini-black holes, and a nonzero 'vacuum' energy. All of these can be constrained in nature by observational data on the extragalactic background light and the microwave background radiation. Black holes and the vacuum can be ruled out as significant contributors to the 'missing mass'. Light axions are also unlikely candidates; however, those with extremely small rest energies (the so-called 'invisible' axions) remain feasible. Light neutrinos, like those proposed by Sciama, are marginally viable. In general, we believe that the intergalactic radiation field is an important way of constraining all types of dark matter.

Overduin, J. M.; Wesson, P. S.

1992-01-01

13

Probing the Intergalactic Medium at Low Redshift  

NASA Astrophysics Data System (ADS)

Cosmological hydrodynamic simulations predict that a substantial fraction of the baryonic material at low redshift should be in the form of a warm/hot (log T = 5-7) intergalactic medium (WHIM). We propose to on X-ray bright quasar (H 1426+428) with the Chandra HETGS to search for the absorption produced by this WHIM gas and determine whether it can account for the apparent baryon deficit in the present-day universe. Our simulations show that we should be able to detect several resonant absorption lines from highly-ionized metals (such as O VII and O VIII) in the WHIM gas. These data will also be useful for studying absorption and/or emission lines intrinsic to the quasars.

Canizares, Claude

2002-09-01

14

Probing the Intergalactic Medium at Low Redshift  

NASA Astrophysics Data System (ADS)

Cosmological hydrodynamic simulations predict that a substantial fraction of the baryonic material at low redshift should be in the form of a warm/hot (log T = 5-7) intergalactic medium (WHIM). We propose to observe three X-ray bright quasars (3C 279, 1H 0414+009, 1ES 1028+511) with the Chandra HETGS to search for the absorption produced by this WHIM gas and determine whether it can account for the apparent baryon deficit in the present-day universe. Our simulations show that we should be able to detect several resonant absorption lines from highly-ionized metals (such as O VII and O VIII) in the WHIM gas. These data will also be useful for studying absorption and/or emission lines intrinsic to the quasars.

Canizares, Claude

2001-09-01

15

The Warm-Hot Intergalactic Medium  

NASA Technical Reports Server (NTRS)

This grant is associated to a 5-year LTSA grant, on "Studying the Largest Reservoir of Baryons in the Universe: The Warm-Hot Intergalactic Medium". The first year of work within this program has been very rich, and has already produced several important results, as detailed in this paper. Table 2 of our original proposal justification, listed the planned year-by-year program, divided into two sub-fields: (A) the study of the z=0 (or Local Group WHIM) system, and (B) the study of the z greater than 0 (i.e- intervening WHIM) systems. For each of the two sub-fields we had planned to analyze, in the first year, a number of archival (Chandra, XMM and FUSE) and new (if observed) sightlines. Moreover, the plan for the z=0 system included the search for new interesting sightlines. We have accomplished all these tasks.

Hayes, Jeffrey (Technical Monitor)

2005-01-01

16

Intergalactic medium metal enrichment through dust sputtering  

NASA Astrophysics Data System (ADS)

We study the motion of dust grains into the intergalactic medium (IGM) around redshift z= 3, to test the hypothesis that grains can efficiently pollute the gas with metals through sputtering. We use the results available in the literature for radiation-driven dust ejection from galaxies as initial conditions and follow the motion onwards. Via this mechanism, grains are ejected into the IGM with velocities >100 km s-1 as they move supersonically, grains can be efficiently eroded by non-thermal sputtering. However, Coulomb and collisional drag forces effectively reduce the charged grain velocity. Up-to-date sputtering yields for graphite and silicate (olivine) grains have been derived using the code TRANSPORT OF IONS IN MATTER (TRIM), for which we provide analytic fits. After training our method on a homogeneous density case, we analyse the grain motion and sputtering in the IGM density field as derived from a ? cold dark matter (CDM) cosmological simulation at z= 3.27. We found that only large (a>~ 0.1?m) grains can travel up to considerable distances (few ×100 kpc physical) before being stopped. Resulting metallicities show a well-defined trend with overdensity ?. The maximum metallicities are reached for 10 < ? < 100[corresponding to systems, in quasi-stellar object (QSO) absorption spectra, with 14.5 < log N(HI) < 16]. However the distribution of sputtered metals is very inhomogeneous, with only a small fraction of the IGM volume polluted by dust sputtering (filling factors of 18 per cent for Si and 6 per cent for C). For the adopted size distribution, grains are never completely destroyed; nevertheless, the extinction and gas photoelectric heating effects resulting from this population of intergalactic grains are well below current detection limits.

Bianchi, Simone; Ferrara, Andrea

2005-04-01

17

Giant radio galaxies - I. Intergalactic barometers  

NASA Astrophysics Data System (ADS)

We present new wideband radio observations with the Australia Telescope Compact Array of a sample of 12 giant radio galaxies. The radio observations are part of a larger radio-optical study aimed at relating the radio structures with the ambient medium on large scales. With projected linear sizes larger than 0.7 Mpc, these objects are ideal candidates for the study of the warm-hot intergalactic medium (WHIM). The sample includes sources with sizes spanning 0.8-3.2 Mpc and total powers of 1.2 × 1024 to 4.0 × 1026 W Hz-1 at 2.1 GHz. Redshifts were limited to z ? 0.15 to permit spectroscopic observations of the hosts and neighbouring galaxies, which were obtained using the AAOmega spectrograph on the Anglo-Australian Telescope. We derive lobe energy densities from the radio observations via equipartition arguments. The inferred pressures in the lobes of the giant radio sources, which range from 1.1 × 10-15 to 2.0 × 10-14 Pa (80 to 1500 cm-3 K), are lower than previously inferred from X-ray observations of dense filaments. Comparison with the OverWhelmingly Large Simulations suggests that the WHIM in pressure balance with the radio lobes has a temperature in excess of ˜106.5 K or a particle overdensity in the range 50-500. This study highlights the capability of next generation surveys, such as the Evolutionary Map of the Universe survey with the Australian Square Kilometre Array Pathfinder, to study populations of giant radio sources at lower surface brightness and thereby discriminate between models for the cosmological evolution of the intergalactic medium and examine the validity of cosmological hydrodynamical simulations.

Malarecki, J. M.; Staveley-Smith, L.; Saripalli, L.; Subrahmanyan, R.; Jones, D. H.; Duffy, A. R.; Rioja, M.

2013-06-01

18

The intergalactic medium: Absorption, emission, disruption  

NASA Astrophysics Data System (ADS)

Two fundamental predictions of modern cosmological models are that (i) galaxies form from small perturbations in the cosmic density field and (ii) there is a tenuous medium between the galaxies that traces the underlying dark matter distribution in a relatively simple way. This thesis concerns the structure of the intergalactic medium (IGM) and its relation to galaxies. Specifically, I analyze the nature of the IGM, observable via the Ly[alpha] transition of hydrogen, as predicted from cosmological hydrodynamic simulations of a cold dark matter + dark energy universe. I first quantify the relation between galaxies and absorption in the Ly[alpha] forest on large (~10 Megaparsec) and small (~0.5 Megaparsec) scales and show that, in the absence of feedback from the galaxies themselves, observations of this relation can serve as robust tests of the inflationary cold dark matter model. I show that the strong bias of high redshift galaxies toward high density regions imprints a clear signature on the distribution of flux in the Ly[alpha] forest, and these predictions are examined as functions of galaxy baryon mass, star formation rate, and dark matter halo mass and occupation. I then investigate the potential impact of galaxies on the IGM and find that supernova-driven winds (as predicted in cosmological simulations) can substantially impact their local surroundings, particularly via heating, but that only very powerful winds can create easily detectable "holes" in the IGM. The impact of winds on the Ly[alpha] optical depth near galaxies is less dramatic than their impact on gas temperature because winds heat only a small fraction of the gas present in the turnaround regions surrounding galaxies, all of which contribute to the Ly[alpha] forest near galaxies. Finally, I combine a Monte Carlo radiative transfer code with cosmological hydrodynamic simulations to investigate the signature of fluorescent Ly[alpha] emission from large scale structure due to impinging radiation from the metagalactic ionizing background as well as local bright sources such as quasars. I compare these predictions with current observations and discuss future observing campaigns and realistic strategies for detecting fluorescence from the ambient metagalactic ionization as well as in the vicinity of bright quasars.

Kollmeier, Juna A.

19

From Galaxies to the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Deep in dark matter halos, galaxies are large factories that convert gas into stars. Gas is accreted from the expansive intergalactic medium (IGM); stars process this gas by fusing lighter elements into heavier ones. In this Dissertation, I combine both observations and theories from a variety of subfields of astrophysics with analytic and numerical models in an aim for a comprehensive understanding of the underlying physics of star formation feedback, galaxy chemical evolution, and the IGM. The mass-metallicity relation is an observed tight correlation between the stellar masses and gas-phase oxygen abundances of star-forming galaxies. I show that while the intrinsic scatter in this relation is small, extreme outliers do exist; I argue that these outliers have unusual metallicities for their masses because they have unusual gas fractions for their masses. The low-mass high-metallicity galaxies appear to be nearing the end of their star formation, and thus should have abnormally small gas reservoirs with which to dilute their metals. On the other hand, the high-mass low-metallicity galaxies appear to be undergoing gas-rich galaxy mergers, implying that they have larger-than-normal amounts of gas diluting their metals. I then show through analytic arguments that while gas fractions can have a large impact on observed metallicities, the low-redshift mass-metallicity relation is dominated by outflow properties because typical galaxies have relatively small gas fractions. Specifically, the mass-metallicity relation implies that the efficiency with which galaxies expel metals should scale steeply with galaxy mass. Combining this model with reasonable models for star formation feedback, I show that the outflow metallicity should likewise vary with galaxy mass; future measurements of wind metallicity can therefore inform models of the physics underlying galaxy winds. The high-redshift IGM is primarily observed through the Lyman-alpha absorption of neutral hydrogen along the line of sight to a distant quasar. As samples of close quasar pairs increase, so does the amount of potential information in the Lya forest transverse to the line-of-sight. Using two cosmological hydrodynamic simulations with different photoionization heating rates and thus different IGM temperature-density relations, I show that the small-scale structure in the Lya forest along the line of sight is dominated by the current thermal state of the gas. On the other hand, the transverse signal is sensitive to - and thus could be used to place unique constraints on - the thermal history of the gas. Finally, I investigate how a two-phase medium is treated in a suite of idealized smoothed particle hydrodynamic (SPH) simulations. I show that cold, dense spherical blobs become over-pressured relative to their hot, tenuous surroundings, arguing that this is because of an effective numerical surface tension owing to the un-resolveable density discontinuity. I then test one proposed modification to how pressure gradients are calculated in SPH, the so-called "relative pressure SPH" (rpSPH); while rpSPH leads to a more uniform pressure across the simulation, I show that it is ultimately unstable because of its lack of momentum conservation.

Peeples, Molly S.

2010-07-01

20

Intergalactic Helium Absorption toward High-Redshift Quasars  

NASA Technical Reports Server (NTRS)

The recent Hubble Space Telescope (HST) observations of the z(q) = 3.286 quasar Q0302-003 (Jakobsen et at. 1994) and the z(q) = 3.185 quasar Q1935-67 by Tytler (1995) show absorption edges at the redshifted wavelength of He II 304 A. A key goal is to distinguish between contributions from discrete Ly-alpha forest clouds and a smoothly distributed intergalactic medium (IGM). We model the contributions from each of these sources of He II absorption, including the distribution of line Doppler widths and column densities, the 'He II proximity effect' from the quasar, and a self-consistent derivation of the He II opacity of the universe as a function of the spectrum of ionizing sources, with the assumption that both the clouds and the IGM are photoionized. The He II edge can be fully accounted for by He II line blanketing for reasonable distributions of line widths and column densities in the Ly-alpha forest, provided that the ionizing sources have spectral index alpha(s) greater than 1.5, and any He II proximity effect is neglected. Even with some contribution from a diffuse IGM, it is difficult to account for the edge observed by Jakobsen et al. (1994) with a 'hard' source spectrum (alpha(s) less than 1.3). The proximity effect modifies the relative contributions of the clouds and IGM to tau(He II) near the quasar (z approx. less than z(q)) and markedly increases the amount of He II absorption required. This implies, for example, that to account for the He II edge with line blanketing alone, the minimum spectral index alpha(s) must be increased from 1.5 to 1.9. We demonstrate the need for higher resolution observations that characterize the change in transmission as z approaches z(q) and resolve line-free gaps in the continuum. We set limits on the density of the diffuse IGM and suggest that the IGM and Ly-alpha clouds are likely to be a significant repository for dark baryons.

Giroux, Mark L.; Fardal, Mark A.; Shull, J. Michael

1995-01-01

21

An updated analytic model for attenuation by the intergalactic medium  

NASA Astrophysics Data System (ADS)

We present an updated version of the so-called Madau model for attenuation of the radiation from distant objects by intergalactic neutral hydrogen. First, we derive the distribution function of intergalactic absorbers from the latest observational statistics of the Ly? forest, Lyman-limit systems and damped Ly? systems. The distribution function reproduces the observed redshift evolution of the Ly? depression and the mean-free path of the Lyman continuum excellently and simultaneously. We then derive a set of analytic functions describing the mean intergalactic attenuation curve for objects at z > 0.5. The new model predicts less (or more) Ly? attenuation for z ? 3-5 (z > 6) sources through the usual broad-band filters relative to the original Madau model. This may cause a systematic difference in the photometric redshift estimates, which is, however, still small: about 0.05. Finally, we find a more than 0.5 mag overestimation of Lyman-continuum attenuation in the original Madau model at z > 3, which causes a significant overcorrection against direct observations of the Lyman continuum of galaxies.

Inoue, Akio K.; Shimizu, Ikkoh; Iwata, Ikuru; Tanaka, Masayuki

2014-08-01

22

Sensitivity of {gamma}-ray telescopes for detection of magnetic fields in the intergalactic medium  

SciTech Connect

We explore potential of current and next-generation {gamma}-ray telescopes for the detection of weak magnetic fields in the intergalactic medium. We demonstrate that using two complementary techniques, observation of extended emission around point sources and observation of time delays in {gamma}-ray flares, one would be able to probe most of the cosmologically and astrophysically interesting part of the 'magnetic field strength' vs 'correlation length' parameter space. This implies that {gamma}-ray observations with Fermi and ground-based Cherenkov telescopes will allow to (a) strongly constrain theories of the origin of magnetic fields in galaxies and galaxy clusters and (b) discover, constrain or rule out the existence of weak primordial magnetic field generated at different stages of evolution of the Early Universe.

Neronov, A.; Semikoz, D. V. [ISDC Data Center for Astrophysics, Chemin d'Ecogia 16, 1290 Versoix, Switzerland and Geneva Observatory, 51 ch. des Maillettes, CH-1290 Sauverny (Switzerland); APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13, France and Institute for Nuclear Research RAS, 60th October Anniversary prosp. 7a, Moscow, 117312 (Russian Federation)

2009-12-15

23

COSMOLOGICAL X-RAY SCATTERING FROM INTERGALACTIC DUST  

SciTech Connect

High-resolution X-ray imaging offers a unique opportunity to probe the nature of dust in the z {approx}< 2 universe. Dust grains 0.1-1 {mu}m in size will scatter soft X-rays, producing a diffuse 'halo' image around an X-ray point source, with a brightness of {approx} few percent confined to an arcminute-sized region. We derive the formulae for scattering in a cosmological context and calculate the surface brightness of the scattering halo due to (1) an intergalactic medium (IGM) uniformly enriched ({Omega}{sub d} {approx} 10{sup -5}) by a power-law distribution of grain sizes and (2) a damped Ly{alpha} type (N{sub H} {approx} 10{sup 21} cm{sup -2}) dust screen at cosmological distances. The morphology of the surface brightness profile can distinguish between the two scenarios above, place size constraints on dusty clumps, and constrain the homogeneity of the IGM. Thus, X-ray scattering can gauge the relative contribution of the first stars, dwarf galaxies, and galactic outflows to the cosmic metallicity budget and cosmic history of dust. We show that, because the amount of intergalactic scattering is overestimated for photon energies <1 keV, the non-detection of an X-ray scattering halo by Petric et al. is consistent with 'gray' intergalactic dust grains ({Omega}{sub d} {approx} 10{sup -5}) when the data are restricted to the 1-8 keV band. We also calculate the systematic offset in magnitude, {delta}m {approx} 0.01, for such a population of graphite grains, which would affect the type of supernova survey ideal for measuring dark energy parameters within {approx}1% precision.

Corrales, Lia; Paerels, Frits, E-mail: lia@astro.columbia.edu [Columbia Astrophysics Laboratory and Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)

2012-06-01

24

Could intergalactic dust obscure a neutrino decay signature?  

NASA Astrophysics Data System (ADS)

Following recent results from the Super-Kamiokande experiment which indicate that neutrinos may have finite masses and provide at least part of the dark matter in the Universe, we re-examine the decaying neutrino hypothesis of Sciama, including for the first time the effects of absorption by intergalactic dust. We consider several dust models, including one designed to optimize ultraviolet extinction for a given dust-to-gas ratio. Dust absorption is insufficient to reconcile the theory with observational upper limits on the intensity of the diffuse ultraviolet background reported recently by Murthy et al. The theory remains marginally compatible with other diffuse background measurements.

Overduin, J. M.; Seahra, S. S.; Duley, W. W.; Wesson, P. S.

1999-09-01

25

Starbursts triggered by intergalactic tides andinterstellar compressive turbulence  

NASA Astrophysics Data System (ADS)

Using parsec-resolution simulations of a typical galaxy merger, we study the triggering of starbursts by connecting the (inter-)galactic dynamics to the structure of the interstellar medium. The gravitational encounter between two galaxies enhances tidal compression over large volumes, which increases and modifies the turbulence, in particular its compressive mode with respect to the solenoidal one. This generates an excess of dense gas leading to intense star formation activity. Along the interaction, the compressive turbulence modifies the efficiency of gas-to-star conversion which, in the Schmidt-Kennicutt diagram, drives the galaxies from the sequence of discs to that of starbursts.

Renaud, Florent; Bournaud, Frédéric; Kraljic, Katarina; Duc, Pierre-Alain

2014-07-01

26

Photoionization of intergalactic gas and cooling flows in clusters of galaxies  

Microsoft Academic Search

We examine the environmental impact of quasars on the intergalactic medium (IGM) and derive analytic and numerical results for ionization-front expansion as a function of redshift z in an expanding Friedmann cosmology. We find that in order for the IGM to be ionized by quasars, the closure parameter of intergalactic gas, omegaI is less than .03. We present new photoionization

Megan Elizabeth Donahue

1990-01-01

27

Observable signatures of the low-z circumgalactic and intergalactic media: ultraviolet line emission in simulations  

NASA Astrophysics Data System (ADS)

We present for the first time predictions for ultraviolet (UV) line emission of intergalactic and circumgalactic gas from Adaptive Mesh Resolution (AMR) large-scale structure simulations at redshifts 0.3 < z < 1.2, with a specific emphasis on its observability with current and near-future UV instrumentation. In the three UV transitions of interest (Ly?, O VI and C IV), there is a clear bimodality in the type of emitting objects: the overwhelming majority of the flux stems from discrete, compact sources, while a much larger fraction of the volume is filled by more tenuous gas. We characterize both object types with regard to their number densities, physical sizes and shapes, brightnesses and luminosities, velocity structures, masses, temperatures, ionization states, and metal content. Degrading our AMR grids to characteristic resolutions offered by available (such as FIREBall) or foreseeable instrumentation allows us to assess which inferences can be drawn from currently possible observations, and to set foundations to prepare observing strategies for future missions. In general, the faint emission of the intergalactic medium (IGM) and filamentary structure remains beyond the capabilities of instruments with only short-duration exposure potential (i.e. stratospheric balloons), even for the most optimistic assumption for Ly?, while the yet fainter metal line transitions (O VI and C IV) for these structures will actually remain challenging for long-duration exposures (i.e. space-based telescopes), mostly due to their low metallicities pushing them more than three orders of magnitudes in brightness below the Ly? radiation. For the bright, circumgalactic medium, the situation is much more promising, and it is foreseeable that in the near future we will not only just detect such sources, but also the combination of all three lines in addition to velocity information will yield valuable insight into the physical processes at hand, illuminating (and discriminating between) important mechanisms during the formation of galaxies and their backreaction on to the IGM from whence they formed.

Frank, S.; Rasera, Y.; Vibert, D.; Milliard, B.; Popping, A.; Blaizot, J.; Courty, S.; Deharveng, J.-M.; Péroux, C.; Teyssier, R.; Martin, C. D.

2012-02-01

28

Observational Search for Negative Matter in Intergalactic Voids  

NASA Technical Reports Server (NTRS)

Negative matter is a hypothetical form of matter with negative rest mass, inertial mass, and gravitational mass. It is not antimatter. If negative matter could be collected in macroscopic amounts, its negative inertial property could be used to make an continuously operating propulsion system which requires neither energy nor reaction mass, yet still violates no laws of physics. Negative matter has never been observed, but its existence is not forbidden by the laws of physics. We propose that NASA support an extension to an ongoing astrophysical observational effort by da Costa, et al. (1996) which could possibly determine whether or not negative matter exists in the well-documented but little-understood intergalactic voids.

Forward, Robert L.

1999-01-01

29

Implications for High Energy Blazar Spectra from Intergalactic Absorption Calculations  

NASA Technical Reports Server (NTRS)

Given a knowledge of the density spectra intergalactic low energy photons as a function of redshift, one can derive the intrinsic gamma-ray spectra and luminosities of blazars over a range of redshifts and look for possible trends in blazar evolution. Stecker, Baring & Summerlin have found some evidence hinting that TeV blazars with harder spectra have higher intrinsic TeV gamma-ray luminosities and indicating that there may be a correlation of spectral hardness and luminosity with redshift. Further work along these lines, treating recent observations of the blazers lES02291+200 and 3C279 in the TeV and sub-TeV energy ranges, has recently been explored by Stecker & Scully. GLAST will observe and investigate many blazars in the GeV energy range and will be sensitive to blazers at higher redshifts. I examine the implications high redshift gamma-ray absorption for both theoretical and observational blazer studies.

Stecker, F

2008-01-01

30

X-ray constraints on the intergalactic medium  

NASA Technical Reports Server (NTRS)

We use ROSAT Position Sensitive Proportional Counter (PSPC) spectra of z approximately equal 3 quasars to constrain the density and temperature of the intergalactic medium (IGM). Strong low-energy cutoffs in PSPC spectra of high-redshift quasars are common. However, the absence of absorption toward some high-redshift quasars can be used to put limits on the possible cosmological density, Omega(sub G), of a hot diffuse intergalactic medium (IGM), via an X-ray Gunn-Peterson test using edge and line opacity in the soft X-rays. The K-edges of oxygen, neon, and carbon and the L-edge of iron produce most of the absorption which is spread out by the redshift of the source. We assume an isotropic, isothermal, nonevolving model of the IGM and calculate the optical depth of this absorption. We find that this test can constrain an enriched IGM at temperatures near 10(exp 5) - 10(exp 6) K, intermediate between the hot IGM ruled out by COBE, and the cold IGM ruled out by the traditional Ly alpha Gunn -Peterson test. Photoionization if the IGM by the ultraviolet and X-ray background has a large effect. We give results for three z approximately equal 3 quasars and discuss how the various trade-offs among temperature, abundance, and backgroud radiation strength affect the limits on Omega (sub G). In addition to the high-redshift case, we discuss techniques for constraining the IGM using X-ray spectra of low-redhift quasars (z approximately equal 0.1 - 0.3). Currently available X-ray spectral data have insufficient energy resolution to constrain the IGM umambiguously, and so expected detection limits for future high-resolution spectrometers are presented. We find that with a large effective area (approximately 2000 sq cm), it is possible to substantially constrain or detect the IGM at the densities which are typically predicted.

Aldcroft, Thomas; Elvis, Martin; Mcdowell, Jonathan; Fiore, Fabrizio

1994-01-01

31

Testing the Warm-Hot Intergalactic Medium Paradigm  

NASA Astrophysics Data System (ADS)

Cosmological hydrodynamical simulations predict that 30%-40% of the low-redshift baryons reside in a collisionally ionized phase {log T 5 to 7} of the intergalactic medium {IGM} associated with large-scale, unvirialized filaments of galaxies. Recent surveys of O VI gas have lent some support to the presence of this warm-hot intergalactic medium {WHIM}, but the results are significantly limited by uncertainties in the ionization mechanism {photo- vs. collisionally ionized} and metallicity of the gas. We are pursuing a large program to test predictions of the WHIM and to improve existing measurements of the OVI absorbers. The primary goals are {i} to increase the redshift path for detection of the hottest IGM, previously only accessible through X-ray absorption studies, using EUV absorption from Ne VIII and Mg X, and {ii} to constrain the IGM physics using UV absorption from H I Ly-alpha, C III, C IV, and O VI. Our team has been awarded a FUSE Legacy program to probe the moderate-redshift WHIM using unique ionization diagnostics in the restframe EUV waveband, including O V, Ne VIII and Mg X. Here we propose to complement our FUSE Legacy program with STIS intermediate-resolution echelle-mode observations of five moderate-redshift {0.45 < z < 0.98} AGNs. The unique combination of FUSE EUV and STIS UV spectra will allow us {1} to test the current models of the WHIM by studying the ionization mechanisms responsible for producing highly-ionized metals in the IGM and determining the frequency of genuine high-temperature metal absorbers in the low-redshift IGM; {2} to investigate the relationship between WHIM and large-scale galaxy structures using galaxy redshift measurements obtained with DEIMOS on Keck and IMACS at Las Campanas Observatory; and {3} to determine the ionization state and metallicity of O VI absorbers in order to accurately assess their contribution to the total baryon budget. Finally, we will make high-level science products derived from these data freely available to the general astronomical community.

Howk, J.

2004-07-01

32

Fluctuations of the intergalactic ionization field at redshift z ~ 2  

NASA Astrophysics Data System (ADS)

Aims: To probe the spectral energy distribution (SED) of the ionizing background radiation at z ? 2 and to specify the sources contributing to the intergalactic radiation field. Methods: The spectrum of a bright quasar HS 1103+6416 (zem = 2.19) contains five successive metal-line absorption systems at zabs = 1.1923, 1.7193, 1.8873, 1.8916, and 1.9410. The systems are optically thin and reveal multiple lines of different metal ions with the ionization potentials lying in the extreme ultraviolet (EUV) range (~1 Ryd to ~0.2 keV). For each system, the EUV SED of the underlying ionization field is reconstructed by means of a special technique developed for solving the inverse problem in spectroscopy. For the zabs = 1.8916 system, the analysis also involves the He I resonance lines of the Lyman series and the He i?504 Å continuum, which are seen for the first time in any cosmic object except the Sun. Results: From one system to another, the SED of the ionizing continuum changes significantly, indicating that the intergalactic ionization field at z ? 2 fluctuates at the scale of at least ?z ~ 0.004. This is consistent with ?z ? 0.01 estimated from He II and H I Lyman-? forest measurements between the redshifts 2 and 3. A radiation intensity break by approximately an order of magnitude at E = 4 Ryd in SEDs restored for the zabs = 1.1923, 1.8873, 1.8916, and 1.9410 systems points to quasars as the main sources of the ionizing radiation. The SED variability is mostly caused by a small number of objects contributing at any given redshift to the ionizing background; at scales ?z ? 0.05, the influence of local radiation sources becomes significant. A remarkable SED restored for the zabs = 1.7193 system, with a sharp break shifted to E ~ 3.5 Ryd and a subsequent intensity decrease by ~1.5 dex, indicates a source with comparable inputs of both hard (active galactic nuclei, AGN) and soft (stellar) radiation components. Such a continuum can be emitted by (ultra) luminous infrared galaxies, many of which reveal both a strong AGN activity and intense star formation in the circumnuclear regions.

Agafonova, I. I.; Levshakov, S. A.; Reimers, D.; Hagen, H.-J.; Tytler, D.

2013-04-01

33

Prospect on intergalactic magnetic field measurements with gamma-ray instruments  

NASA Astrophysics Data System (ADS)

Observing high-energy gamma-rays from Active Galactic Nuclei (AGN) offers a unique potential to probe extremely tiny values of the intergalactic magnetic field (IGMF), a long standing question of astrophysics, astroparticle physics and cosmology. Very high energy (VHE) photons from blazars propagating along the line of sight interact with the extragalactic background light (EBL) and produce e + e - pairs. Through inverse-Compton interaction, mainly on the cosmic microwave background (CMB), these pairs generate secondary GeV-TeV components accompanying the primary VHE signal. Such secondary components would be detected in the gamma-ray range as delayed ``pair echos'' for very weak IGMF (B < 10-16 G), while they should result in a spatially extended gamma-ray emission around the source for higher IGMF values (B > 10-16 G). Coordinated observations with space (i.e. Fermi) and ground-based gamma-ray instruments, such as the present Cherenkov experiments H.E.S.S., MAGIC and VERITAS, the future Cherenkov Telescope Array (CTA) Observatory, and the wide-field detectors such as HAWC and LHAASO, should allow to analyze and finally detect such echos, extended emission or pair halos, and to further characterize the IGMF.

Sol, Hélène; Zech, Andreas; Boisson, Catherine; Krawczynski, Henric; Fallon, Lisa; de Gouveia Dal Pino, Elisabete; Hinton, Jim; Inoue, Susumu; Neronov, Andrii; White, Richard

2013-07-01

34

The filling factor of intergalactic metals at redshift z= 3  

NASA Astrophysics Data System (ADS)

Observations of quasar absorption-line systems reveal that the z= 3 intergalactic medium (IGM) is polluted by heavy elements down to H I optical depths ?H I? 10. What is not yet clear, however, is what fraction of the volume needs to be enriched by metals and whether it suffices to enrich only regions close to galaxies in order to reproduce the observations. We use gas density fields derived from large cosmological simulations, together with synthetic quasar spectra and imposed model metal distributions, to investigate what enrichment patterns can reproduce the observed median optical depth of C IV as a function of ?H I. Our models can only satisfy the observational constraints if the z= 3 IGM was primarily enriched by galaxies that reside in low-mass (mtot < 1010 M?) haloes that can eject metals out to distances >rsim 102 kpc. Galaxies in more massive haloes cannot possibly account for the observations as they are too rare for their outflows to cover a sufficiently large fraction of the volume. Galaxies need to enrich gas out to distances that are much greater than the virial radii of their host haloes. Assuming the metals to be well mixed on small scales, our modelling requires that the fractions of the simulated volume and baryonic mass that are polluted with metals are, respectively, >10 per cent and >50 per cent in order to match observations.

Booth, C. M.; Schaye, Joop; Delgado, J. D.; Dalla Vecchia, Claudio

2012-02-01

35

Exploring the intergalactic magnetic field by means of Faraday tomography  

NASA Astrophysics Data System (ADS)

Unveiling the intergalactic magnetic field (IGMF) in filaments of galaxies is a very important and challenging subject in modern astronomy. In order to probe the IGMF from rotation measures (RMs) of extragalactic radio sources, we need to separate RMs due to other origins such as the source, intervening galaxies, and our Galaxy. In this paper, we discuss observational strategies for the separation by means of Faraday tomography (Faraday RM synthesis). We consider an observation of a single radio source such as a radio galaxy or a quasar viewed through the Galaxy and the cosmic web. We then compare the observation with another observation of a neighboring source with a small angular separation. Our simulations with simple models of the sources suggest that it would be not easy to detect the RM due to an IGMF of order ˜ 1 rad m-2, an expected value for the IGMF through a single filament. Contrary to this, we find that an RM of at least ˜ 10 rad m-2 could be detected with the Square Kilometre Array or its pathfinders/precursors, if we achieve selection of ideal sources. These results would be improved if we incorporated decomposition techniques such as RMCLEAN and QU-fitting. We discuss the feasibility of the strategies for cases with complex Galactic emissions as well as with effects of observational noise and radio frequency interferences.

Akahori, Takuya; Kumazaki, Kohei; Takahashi, Keitaro; Ryu, Dongsu

2014-06-01

36

Cosmological Halos: a Search for the Ionized Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Standard big bang nucleosynthesis predicts the average baryon density of the Universe to be a few percent of the critical density. Only about one tenth of the predicted baryons have been seen. A plausible repository for the missing baryons is in a diffuse ionized intergalactic medium (IGM). In an attempt to measure the IGM we searched for Thomson-scattered halos around strong high redshift radio sources. Observations of the radio source 1935-692 were made with the Australia Telescope Compact Array. We assumed a uniform IGM, and isotropic steady emission of 1935-692 for a duration between 107-108 years. A model of the expected halo visibility function was used in ?2 fits to place upper limits on ? IGM. The upper limits varied depending on the methods used to characterize systematic errors in the data. The results are 2? limits of ? IGM < 0.65. While not yet at the sensitivity level to test primordial nucleosynthesis, improvements on the technique will probably allow this in future studies.

Geller, Robert Maurice

37

Casting Light on the Warm-Hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

It has been known for over a decade that the observed baryons in the local universe fall far short of the amount required by cosmological models. Simulations suggest that the bulk of the so-called "missing baryons" is contained in the shock-heated warm-hot intergalactic medium (WHIM). Despite considerable effort, direct detection of the WHIM has proved difficult. Perhaps the best probe of the WHIM is spectroscopic observations of high ionization species in the spectra of background QSOs. In particular, the ultraviolet lines of Ne VIII(lambda)(lambda)770.5,780.3 are expected to be a powerful tracer of hot collisionally ionized gas. Unfortunately, only two Ne VIII absorption systems have been found to date because of the limits of UV spectrographs. The successful installation of COS on HST should soon change this situation. As demonstrated by our recent study of the Ne VIII absorber toward HE0226-4110, deep spectroscopic surveys of galaxies in the vicinity of absorbers are required to distinguish between the WHIM and other possible origins for the warm gas. Unfortunately, such studies will be difficult for Ne VIII systems discovered with COS because they will all be at z > 0.5. However, there is one additional lower redshift Ne VIII system discovered by FUSE for which the galactic environment has not been quantified. Here, we propose to use GMOS on Gemini north to complete a galaxy survey around this absorber to better understand Ne VIII as a probe of the WHIM.

Mulchaey, John S., , Dr.; Chen, Hsiao-Wen, , Dr.

2010-02-01

38

Broad H I Absorbers as Metallicity-independent Tracers of the Warm-Hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Thermally broadened Ly? absorbers (BLAs) offer an alternative method to highly ionized metal lines for tracing the warm-hot intergalactic medium (WHIM) at T>105 K. However, observing BLAs requires data of high quality and accurate continuum definition to detect the low-contrast features, and a good knowledge of the velocity structure to differentiate multiple blended components from a single broad line. Even for well-characterized absorption profiles, disentangling the thermal line width from the various thermal and non-thermal contributors to the observed line width is ambiguous. We compile a catalog of reliable BLA candidates along seven active galactic nucleus sight lines from a larger set of Ly? absorbers observed by the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST). We compare our measurements based on independent reduction and analysis of the data to those published by other research groups. We examine the detailed structure of each absorber and determine a reliable line width and column density. Purported BLAs are grouped into probable (15), possible (48), and non-BLA (56) categories. Combining the first two categories, we infer a line frequency (d{N}/dz)_BLA=18± 11, comparable to observed O VI absorbers, also thought to trace the WHIM. We discuss the overlap between BLA and O VI absorbers (20%-40%) and the distribution of BLAs in relation to nearby galaxies (O VI detections in BLAs are found closer to galaxies than O VI nondetections). We assume that the line width determined through a multi-line curve of growth (COG) is a close approximation to the thermal line width. Based on 164 measured COG H I line measurements, we statistically correct the observed line widths via a Monte Carlo simulation. Gas temperature and neutral fraction f_H I are inferred from these statistically corrected line widths and lead to a distribution of total hydrogen columns. Summing the total column density over the total observed path length, we find a BLA contribution to the closure density of ?BLA = 6.3+1.1 -0.8 × 10-3 h -1 70 based on 104 Monte Carlo simulations of each BLA system. There are a number of critical systematic assumptions implicit in this calculation, and we discuss how each affects our results and those of previously published work. In particular, the most comparable previous study by Lehner et al. gave ?BLA = 3.6 × 10-3 h -1 70 or 9.1 × 10-3 h -1 70, depending on which assumptions were made about hydrogen neutral fraction. Taking our value, current O VI and BLA surveys can account for ~ 20% of the baryons in the local universe while an additional ~ 29% can be accounted for in the photoionized Ly? forest; about half of all baryons in the low-z universe are found in the intergalactic medium. Finally, we present new, high signal-to-noise ratio observations of several of the BLA candidate lines from Early Release Observations made by the Cosmic Origins Spectrograph on HST. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Danforth, Charles W.; Stocke, John T.; Shull, J. Michael

2010-02-01

39

STUDYING THE WARM-HOT INTERGALACTIC MEDIUM IN EMISSION  

SciTech Connect

We assess the possibility of detecting the warm-hot intergalactic medium in emission and characterizing its physical conditions and spatial distribution through spatially resolved X-ray spectroscopy, in the framework of the recently proposed DIOS, EDGE, Xenia, and ORIGIN missions, all of which are equipped with microcalorimeter-based detectors. For this purpose, we analyze a large set of mock emission spectra, extracted from a cosmological hydrodynamical simulation. These mock X-ray spectra are searched for emission features showing both the O VII K{alpha} triplet and O VIII Ly{alpha} line, which constitute a typical signature of the warm-hot gas. Our analysis shows that 1 Ms long exposures and energy resolution of 2.5 eV will allow us to detect about 400 such features per deg{sup 2} with a significance {>=}5{sigma} and reveals that these emission systems are typically associated with density {approx}100 above the mean. The temperature can be estimated from the line ratio with a precision of {approx}20%. The combined effect of contamination from other lines, variation in the level of the continuum, and degradation of the energy resolution reduces these estimates. Yet, with an energy resolution of 7 eV and all these effects taken into account, one still expects about 160 detections per deg{sup 2}. These line systems are sufficient for tracing the spatial distribution of the line-emitting gas, which constitute an additional information, independent from line statistics, to constrain the poorly known cosmic chemical enrichment history and the stellar feedback processes.

Takei, Y.; Mitsuda, K. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Ursino, E.; Branchini, E. [Dipartimento di Fisica, Universita degli Studi 'Roma Tre' via della Vasca Navale 84, I-00146 Roma (Italy); Ohashi, T.; Kawahara, H. [Department of Physics, School of Science, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Piro, L.; Corsi, A. [INAF-Istituto di Astrofisica Spaziale Fisica Cosmica, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Amati, L. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Bologna, via P. Gobetti 101, I-40129 Bologna (Italy); Den Herder, J. W.; Kaastra, J. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Galeazzi, M. [Physics Department of University of Miami, 319 Knight Physics Building, Coral Gables, FL 33164 (United States); Moscardini, L.; Roncarelli, M. [Dipartimento di Astronomia, Universita di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Nicastro, F. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I00040 Monteporzio-Catone (RM) (Italy); Paerels, F. [Columbia Astrophysics Laboratory and Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Viel, M., E-mail: takei@astro.isas.jaxa.jp [INAF-Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131 Trieste (Italy)

2011-06-20

40

Can quasars photoionize the intergalactic medium at high redshift?  

NASA Technical Reports Server (NTRS)

The reionization of the intergalactic medium (IGM) by quasar sources at high redshift are discussed. The integrated UV background from observed QSO's, taking into account the hydrogen opacity associated with intervening Ly-alpha clouds and Lyman limit systems are computed. It is noted that the published data appear to indicate a significant underdensity of absorption systems in the Ly-alpha forest with column densities N(sub HI) greater than 10(exp 15) cm(sup -2). This deficit results in a reduction of the opacity of the universe by a factor of 1.5-3 at z = 3-5 relative to previous estimates. The QSO contribution to the metagalactic flux at the Lyman edge may be as large as J(sub 912)(z) is approximately 6((1 + z)/4.5)(sup 0.5) x 10(exp -22) erg cm(sup -2) s(sup -1) Hz(sup -1) sr(sup -1) for q(sup o) = O, and slightly lower for q(sub o) = 1/2. For a density of the diffuse component of the IGM of omega(sub D)(h(sub 50)(sup 2)) less than 0.025, QSO's could photoionize a smooth IGM sufficiently to satisfy the constraints imposed by the Gunn-Peterson effect. The epoch of reionization could be as recent as z is approximately greater than 5. As a result, neutral patches of IGM would be detectable in the spectra of high redshift quasars. The patches would appear as absorption line systems with typical column densities of 10(exp 19) - 10(exp 20) cm(sup -2), and velocity widths of 100 - 1000 km s(sup -1).

Meiksin, Avery; Madau, Piero

1993-01-01

41

The Fate of the First Galaxies. III. Properties of Primordial Dwarf Galaxies and Their Impact on the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

In two previous papers, we presented simulations of the first galaxies in a representative volume of the universe. The simulations are unique because we model feedback-regulated galaxy formation, using time-dependent, spatially inhomogeneous radiative transfer coupled to hydrodynamics. Here we study the properties of simulated primordial dwarf galaxies with masses <~2×108 Msolar and investigate their impact on the intergalactic medium. While many primordial galaxies are dark, about 100-500 per comoving Mpc3 are luminous but relatively faint. They form preferentially in chain structures and have low surface brightness stellar spheroids extending to 20% of the virial radius. Their interstellar medium has mean density nH~10-100 cm-3, metallicity Z~0.01-0.1 Zsolar, and can sustain a multiphase structure. With large scatter, the mean efficiency of star formation scales with halo mass, ~M2DM, independent of redshift. Because of feedback, halos smaller than a critical mass, Mcrit(z), are devoid of most of their baryons. More interestingly, we find that dark halos have always a smaller Mcrit(z) than luminous ones. Metal enrichment of the intergalactic medium is inhomogeneous, with only a 1%-10% volume filling factor of enriched gas with [Z/H]>-3.0 and 10%-50% with [Z/H]>-5.0. At z~10, the fraction of stars with metallicity Z<10-3 Zsolar is 10-6 of the total stellar mass. However, this study focuses on the effects of radiative feedback: mechanical feedback from SN explosions is only included in two of the seven simulations we have analyzed. Although detections of high-redshift dwarf galaxies with the James Webb Space Telescope will be a challenge, studies of their fossil records in the local universe are promising because of their large spatial density.

Ricotti, Massimo; Gnedin, Nickolay Y.; Shull, J. Michael

2008-09-01

42

Navy Space and Astronautics Orientation.  

ERIC Educational Resources Information Center

Fundamental concepts of the spatial environment, technologies, and applications are presented in this manual prepared for senior officers and key civilian employees. Following basic information on the atmosphere, solar system, and intergalactic space, a detailed review is included of astrodynamics, rocket propulsion, bioastronautics, auxiliary…

Herron, R. G.

43

The Intergalactic Light in HCG 40: Tracing the Dynamics of a Young Galaxy Group  

Microsoft Academic Search

We present results from a deep imaging study of the diffuse intergalactic light (IGL) in a nearby, very compact galaxy group, HCG 40. The IGL arises from stars not gravitationally bound to any individual member galaxy, but moving about in the potential of the whole system. Simulations and observations of other galaxy groups suggest that the IGL can contribute from

Mangala Sharma; T. S. Statler

2007-01-01

44

A Direct Precision Measurement of the Intergalactic Ly? Opacity at 2 <= z <= 4.2  

NASA Astrophysics Data System (ADS)

We measure the evolution of the intergalactic Ly? effective optical depth, ?eff, over the redshift range 2<=z<=4.2 from a sample of 86 high-resolution, high-S/N quasar spectra obtained with the ESI and HIRES spectrographs on Keck and with the MIKE spectrograph on Magellan. This represents an improvement over previous analyses of the Ly? forest from high-resolution spectra in this redshift interval of a factor of 2 in the size of the data set alone. We pay particular attention to robust error estimation and extensively test for systematic effects. We find that our estimates of the quasar continuum levels in the Ly? forest obtained by spline fitting are systematically biased low, with the magnitude of the bias increasing with redshift, but that this bias can be accounted for using mock spectra. The mean fractional error is <1% at z=2, 4% at z=3, and 12% at z=4. Previous measurements of ?eff at z>~3 based on directly fitting the quasar continua in the Ly? forest, which have generally neglected this effect, are therefore likely biased low. We provide estimates of the level of absorption arising from metals in the Ly? forest based on both direct and statistical metal removal results in the literature, finding that this contribution is ~6%-9% at z=3 and decreases monotonically with redshift. The high precision of our measurement, attaining 3% in redshift bins of width ?z=0.2 around z=3, indicates significant departures from the best-fit power-law redshift evolution [?eff=0.0018(1+z)3.92, when metals are left in], particularly near z=3.2. The observed downward departure is statistically consistent with a similar feature detected in a precision statistical measurement using SDSS spectra by Bernardi and coworkers using an independent approach. Based, in part, on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the data analyzed in this work were gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Faucher-Giguère, Claude-André; Prochaska, Jason X.; Lidz, Adam; Hernquist, Lars; Zaldarriaga, Matias

2008-07-01

45

The Low-z Intergalactic Medium. II. Ly?, O VI, and C III Forest  

NASA Astrophysics Data System (ADS)

We present the results of a large survey of H I, O VI, and C III absorption lines in the low-redshift (z<0.3) intergalactic medium (IGM). We begin with 171 strong Ly? absorption lines (W?>=80 mÅ) in 31 AGN sight lines studied with the Hubble Space Telescope and measure corresponding absorption from higher order Lyman lines with FUSE. Higher order Lyman lines are used to determine NHI and bHI accurately through a curve-of-growth (COG) analysis. We find that the number of H I absorbers per column density bin is a power-law distribution, dNscr/dNHI~N-?HI, with ?HI=1.68+/-0.11. We made 40 detections of O VI ??1032, 1038 and 30 detections of C III ?977 out of 129 and 148 potential absorbers, respectively. The column density distribution of C III absorbers has ?CIII=1.68+/-0.04, similar to ?HI but not as steep as ?OVI=2.2+/-0.1. From the absorption-line frequency, dNscrCIII/dz=12+3-2 for W?(C III)>30 mÅ, we calculate a typical IGM absorber size r0~400 kpc, similar to scales derived by other means. The COG-derived b-values show that H I samples material with T<105 K, incompatible with a hot IGM phase. By calculating a grid of CLOUDY models of IGM absorbers with a range of collisional and photoionization parameters, we find it difficult to simultaneously account for the O VI and C III observations with a single phase. Instead, the observations require a multiphase IGM in which H I and C III arise in photoionized regions, while O VI is produced primarily through shocks. From the multiphase ratio NHI/NCIII, we infer the IGM metallicity to be ZC=0.12 Zsolar, similar to our previous estimate of ZO=0.09 Zsolar from O VI.

Danforth, Charles W.; Shull, J. Michael; Rosenberg, Jessica L.; Stocke, John T.

2006-04-01

46

Hubble/COS Observations of Intergalactic Gas Toward PKS 0405-123  

NASA Astrophysics Data System (ADS)

We present an overview of far-UV Hubble Space Telescope observations (1150-1780 A, at 17 km/s resolution) taken by the Cosmic Origins Spectrograph (COS) of the QSO PKS 0405-123 at redshift zem = 0.5726 and FUV flux 3.5x10-14 erg/s/cm2/A. This spectrum illustrates the the power of COS for studying metal-enriched gas between the galaxies, distributed throughout the multiphase intergalactic medium (IGM). We used 7 orbits with 9 FP-split positions, obtained S/N = 35-45 over much of the G130M band (1150-1440 A), and detected numerous absorption features of hydrogen (Lya, Lyb) and heavy-element probes of metallicity. Ions that can be studied include lines (O VI, N V, Ne VIII) sensitive to hot gas produced by strong shocks produced in gravitational inflows to the Cosmic Web, in circumgalactic gas, and in galactic winds. The high S/N allows a search for broad Ly-alpha possibly associated with O VI in hot gas (105 to 106 K). This sight line also intercepts a high-velocity cloud seen in Si III at 110-170 km/s (LSR) and b = -37.55 in the Galactic halo. In the absorption system at z = 0.495, the Ne VIII doublet (770.41, 780.32 A) shifts into the COS band, allowing us to probe the warm-hot IGM at log T = 5.5-6.0, several times deeper than previous (STIS) studies (Prochaska et al. 2004; Howk et al. 2009). In other posters, members of the COS science team describe the detection of O VI absorbers at redshifts z = 0.16710, 0.18292, 0.36156, 0.36332, and 0.49501, including a Lyman Limit system at z = 0.16710 with log N(HI) = 16.45 +/- 0.05. The high S/N observations allow us to measure important ions previously not detected and to evaluate the kinematical relationships and physical conditions among the detected ions.

Shull, J. Michael; Danforth, C.; Froning, C.; Green, J.; Keeney, B.; Stocke, J.; Yao, Y.; Savage, B.; Narayanan, A.; Sembach, K.

2010-01-01

47

THE RELATIONSHIP BETWEEN INTERGALACTIC H I/O VI AND NEARBY (z < 0.017) GALAXIES  

SciTech Connect

We analyze intergalactic H I and O VI absorbers with v < 5000 km s{sup -1} in Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer spectra of 76 active galactic nuclei. The baryons traced by H I/O VI absorption are clearly associated with the extended surroundings of galaxies; for impact parameters <400 kpc they are 2-4 times more numerous as those inside the galaxies. This large reservoir of matter likely plays a major role in galaxy evolution. We tabulate the fraction of absorbers having a galaxy of a given luminosity within a given impact parameter ({rho}) and velocity difference ({delta}v), as well as the fraction of galaxies with an absorber closer than a given {rho} and {delta}v. We identify possible 'void absorbers' ({rho} > 3 Mpc to the nearest L{sub *} galaxy), although at v < 2500 km s{sup -1} all absorbers are within 1.5 Mpc of an L>0.1 L{sub *} galaxy. The absorber properties depend on {rho}, but the relations are not simple correlations. For four absorbers with {rho} = 50-350 kpc from an edge-on galaxy with known orientation of its rotation, we find no clear relation between absorber velocities and the rotation curve of the underlying galaxy. For {rho} < 350 kpc, the covering factor of Ly{alpha} (O VI) around L>0.1 L {sub *} galaxies is 100% (70%) for field galaxies and 65% (10%) for group galaxies; 50% of galaxy groups have associated Ly{alpha}. All O VI absorbers occur within 550 kpc of an L>0.25 L{sub *} galaxy. The properties of three of 14 O VI absorbers are consistent with photoionization, for five the evidence points to collisional ionization; the others are ambiguous. The fraction of broad Ly{alpha} lines increases from z = 3 to z = 0 and with decreasing impact parameter, consistent with the idea that gas inside {approx}500 kpc from galaxies is heating up, although alternative explanations cannot be clearly excluded.

Wakker, B. P.; Savage, B. D. [Department of Astronomy, University of Wisconsin, 475 N. Charter St, Madison, WI 53706 (United States)

2009-05-15

48

Intergalactic Hydrogen Clouds at Low Redshift: Connections to Voids and Dwarf Galaxies  

NASA Technical Reports Server (NTRS)

We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Ly(alpha) clouds located along sightlines to four bright quasars passing through well-mapped galaxy voids (16000 km/s pathlength) and superclusters (18000 km/s). We report two more definite detections of low-redshift Ly(alpha) clouds in voids: one at 3047 km/s (heliocentric) toward Mrk 421 and a second just beyond the Local Supercluster at 2861 km/s toward I Zw 1, confirming our earlier discovery of Ly(alpha) absorption clouds in voids (Stocke et al., ApJ, 451, 24). We have now identified ten definite and one probable low-redshift neutral hydrogen absorption clouds toward four targets, a frequency of approximately one absorber every 3400 km/s above 10(exp 12.7/sq cm column density. Of these ten absorption systems, three lie within voids; the probable absorber also lies in a void. Thus, the tendency of Ly(alpha) absorbers to 'avoid the voids' is not as clear as we found previously. If the Ly(alpha) clouds are approximated as homogeneous spheres of 100 kpc radius, their masses are approximately 10(exp 9)solar mass (about 0.01 times that of bright L* galaxies) and they are 40 times more numerous, comparable to the density of dwarf galaxies and of low-mass halos in numerical CDM simulations. The Ly(alpha) clouds contribute a fraction Omega(sub cl)approximately equals 0.003/h(sub 75) to the closure density of the universe, comparable to that of luminous matter. These clouds probably require a substantial amount of nonbaryonic dark matter for gravitational binding. They may represent extended haloes of low-mass protogalaxies which have not experienced significant star formation or low-mass dwarf galaxies whose star formation ceased long ago, but blew out significant gaseous material.

Shull, J. Michael; Stocke, John T.; Penton, Steve

1996-01-01

49

Secondary Photons and Neutrinos from Distant Blazars and the Intergalactic Magnetic Fields  

NASA Astrophysics Data System (ADS)

Secondary photons and neutrinos produced in the interactions of cosmic ray protons and gamma rays emitted by distant Active Galactic Nuclei (AGN) with the photon background along the line of sight can reveal a wealth of new information about the intergalactic magnetic fields (IGMF), extragalactic background light (EBL), and the acceleration mechanisms of cosmic rays. The secondary photons may have already been observed by gamma-ray telescopes. With the inclusion of secondary photons the current upper limits on the extragalactic background light are significantly weakened and new limits are set for the intergalactic magnetic fields for a wide range of cosmic ray and gamma ray models. Recent results from IceCube may also hint at the first observation of secondary neutrinos. Ramifications for the cosmic backgrounds, magnetic fields, and AGN models will be discussed.

Essey, Warren

2014-06-01

50

The intergalactic medium - Initial and boundary conditions for galaxy and primeval star formation  

NASA Technical Reports Server (NTRS)

New detailed numerical calculations are presented of the evolution of the intergalactic medium (IGM) in a post recombination Friedmann universe, including a solution of the nonequilibrium rate equations for the ionization and recombination of H and He, the energy equation, and the equation of radiative transfer. The implications of this study for the characteristic mass scale and the epoch of gravitational collapse for the average 'first' star-forming clouds are discussed. The star-formation rate and associated metallicity generation implied if the IGM is fully ionized by starlight by redshift greater than 4 as suggested by recent interpretations of the Gunn-Peterson effect are examined. It is shown that the relative strengths of metal lines from a quasar absorption-line Lyman limit system cloud at z = 3 photoionized by the present intergalactic UV radiation background are compatible with the observations, at least for background sources of either AGN-type or star-forming galaxy spectra.

Giroux, Mark L.; Shapiro, Paul R.

1990-01-01

51

X-ray Scattering through the Intergalactic Medium: Time Variability and Ghost Halos  

NASA Astrophysics Data System (ADS)

Dust grains polluting the intergalactic medium (IGM) have a chance of being detected through the phenomenon of X-ray scattering, which produces a diffuse arcminute-scale halo around bright X-ray point sources. We present follow up work to Corrales & Paerels (2012) by calculating the expected intensity of intergalactic dust scattering halos using the more exact Mie scattering treatment. This adjustment is necessary to check for large 0.1-1 micron sized dust grains that would interfere with the photometry needed for high precision measurements of cosmological constants. Even with the supreme focusing power of Chandra, we find that the dust scattering halo intensity is much dimmer than the Chandra PSF wings. However, scattered light takes a longer path to reach the observer, causing intergalactic scattering halos to be delayed ~10,000 years. I investigate the possibility of detecting a scattering halo around a quasar that has recently become dim, or ghost halos from quasars that are no longer visible.

Corrales, Lia

2014-08-01

52

Consequences of Starbursts for the Interstellar and Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Star formation in general, and starbursts in particular, drive the evolution of galaxies. To understand the process of galactic matter cycle quantitatively, it is absolutely necessary to follow the evolution of the components of the interstellar medium, such as gas, magnetic fields, cosmic rays in detail over sufficiently long time scales. Due to the non-linearity of the interactions between the various components, and the turbulent nature of the plasma, high resolution numerical simulations offer the best strategy to further our understanding. The results of our numerical studies can be summarized as follows: (i) Supernova explosions are the most important energy input sources in the ISM and lead to a high level of turbulence in the plasma, coupling structures on all scales, (ii) more than half of the disk mass resides in classically thermally unstable temperature regimes, (iii) turbulent mixing is the dominant energy transport process over a wide range of scales, (iv) proportionality between magnetic field and density is generally weak, except for the densest regions, (v) magnetic fields, even if they are parallel to the galactic disk, cannot prevent outflow into the halo, (vi) the ionization structure of the plasma depends on its thermal history, and is in general not in collisional ionization equilibrium, (vii) the cooling function varies in space and time, (viii) X-rays can be emitted even at plasma temperatures of the order of 104K due to delayed recombination, both in the disk and the halo, (ix) cosmic rays can help driving a galactic wind, (x) cosmic rays can be accelerated to high energies beyond 1015eV (the "knee") in long lived shocks propagating into the galactic halo, because of time-dependent star formation.

Breitschwerdt, Dieter; de Avillez, Miguel; Dorfi, Ernst

53

Generation of galactic disc warps due to intergalactic accretion flows onto the disc  

NASA Astrophysics Data System (ADS)

A new method is developed to calculate the amplitude of the galactic warps generated by a torque due to external forces. This takes into account that the warp is produced as a reorientation of the different rings which constitute the disc in order to compensate the differential precession generated by the external force, yielding a uniform asymptotic precession for all rings. Application of this method to gravitational tidal forces in the Milky Way due to the Magellanic Clouds leads to a very low amplitude of the warp, as has been inferred in previous studies; so, tidal forces are unlikely to generate warps, at least in the Milky Way. If the force were due to an extragalactic magnetic field, its intensity would have to be very high, greater than 1 mu G, to generate the observed warps. An alternative hypothesis is explored: the accretion of the intergalactic medium over the disk. A cup-shaped distortion is expected, due to the transmission of the linear momentum; but, this effect is small and the predominant effect turns out to be the transmission of angular momentum, i.e. a torque giving an integral-sign shape warp. The torque produced by a flow of velocity ~ 100 km s-1 and baryon density ~ 10-25 kg/m3 is enough to generate the observed warps and this mechanism offers quite a plausible explanation. First, because this order of accretion rate is inferred from other processes observed in the Galaxy, notably its chemical evolution. The inferred rate of infall of matter, ~ 1 M_sun/yr, to the Galactic disc that this theory predicts agrees with the quantitative predictions of this chemical evolution resolving key issues, notably the G-dwarf problem. Second, the required density of the intergalactic medium is within the range of values compatible with observation. By this mechanism, we can explain the warp phenomenon in terms of intergalactic accretion flows onto the disk of the galaxy.

López-Corredoira, M.; Betancort-Rijo, J.; Beckman, J. E.

2002-04-01

54

Constrainingquasar and intergalactic medium properties through bubble detection in redshifted 21-cm maps  

NASA Astrophysics Data System (ADS)

The infrared detection of a z > 7 quasar has opened up a window to directly probe the intergalactic medium (IGM) during the epoch of reionization. It is anticipated that future observations will yield more quasars extending to higher redshifts. In this paper, we theoretically consider the possibility of detecting the ionized bubble around a z = 8 quasar using targeted redshifted 21-cm observations with the GMRT. The apparent shape and size of the ionized bubble, as seen by a distant observer, depends on the parameters ? phs /C, xH i /c and ?Q, where ? phs and ?Q are, respectively, the ionizing photon emission rate and age of the quasar, and xH i and C are, respectively, the neutral fraction and clumping factor of the IGM. The 21-cm detection of an ionized bubble, thus, holds the promise of allowing us to probe the quasar and IGM properties at z = 8. In this work we have analytically calculated the apparent shape and size of a quasar's ionized bubble assuming a uniform IGM and ignoring other ionizing sources besides the quasar, and used this as a template for matched-filter bubble search with the GMRT visibility data. We have assumed that ? phs is known from the observed infrared spectrum, and C = 30 from theoretical considerations, which gives us the two free parameters xH i and ?Q for bubble detection. Considering 1000'h of observation, we find that there is a reasonably large region of parameter space bounded within (xH i , (?Q/107 yr ))=(1.0, 0.5) and (0.2, 7.0) where a 3? detection is possible if (? phs /1057 s-1)=3. The available region increases if ? phs is larger, whereas we need xH i ?0.4 and (?Q/107 yr )?2.0 if (? phs /1057 s-1)=1.3. Considering parameter estimation, we find that in many cases it will be possible to quite accurately constrain ?Q and place a lower limit on xH i with 1000'h of observation, particularly if the bubble is in the early stage of growth and we have a very luminous quasar or a high neutral fraction. Deeper follow-up observations (4000 and 9000'h) can be used to further tighten the constraints on ?Q and xH i . We find that the estimated xH i is affected by uncertainty in the assumed value of C. The quasar's age ?Q however is robust and is unaffected by the uncertainty in C. The presence of other ionizing sources and inhomogeneities in the IGM distort the shape and size of the quasar's ionized bubble. This is a potential impediment for bubble detection and parameter estimation. We have used the seminumerical technique to simulate the apparent shape and size of quasar ionized bubbles incorporating these effects. If we consider a 9000'h of observation with the GMRT, we find that the estimated parameters ?Q and xH i are expected to be within the statistical uncertainties.

Majumdar, Suman; Bharadwaj, Somnath; Choudhury, T. Roy

2012-11-01

55

The Galactic halo and local intergalactic medium toward PKS 2155-304  

NASA Technical Reports Server (NTRS)

Low-resolution UV observations of the bright, low-redshift BL Lac object PKS 2155-304 have been obtained by the HST's high-resolution spectrograph. Attention is here given to results on the number of intergalactic H I Ly-alpha components in the line-of-sight toward this object. The highest-redshift of the observed Ly-alpha systems furnishes a lower limit on the distance of the BL Lac object; this distance is consistent with the approximate redshift deduced from CCD imagery of the probable host galaxy for PKS 2155-304.

Bruhweiler, Frederick C.; Boggess, A.; Norman, Dara J.; Grady, C. A.; Urry, C. M.; Kondo, Yoji

1993-01-01

56

A uniform metal distribution in the intergalactic medium of the Perseus cluster of galaxies.  

PubMed

Most of the metals (elements heavier than helium) produced by stars in the member galaxies of clusters currently reside within the hot, X-ray-emitting intra-cluster gas. Observations of X-ray line emission from this intergalactic medium have suggested a relatively small cluster-to-cluster scatter outside the cluster centres and enrichment with iron out to large radii, leading to the idea that the metal enrichment occurred early in the history of the Universe. Models with early enrichment predict a uniform metal distribution at large radii in clusters, whereas those with late-time enrichment are expected to introduce significant spatial variations of the metallicity. To discriminate clearly between these competing models, it is essential to test for potential inhomogeneities by measuring the abundances out to large radii along multiple directions in clusters, which has not hitherto been done. Here we report a remarkably uniform iron abundance, as a function of radius and azimuth, that is statistically consistent with a constant value of ZFe = 0.306?±?0.012 in solar units out to the edge of the nearby Perseus cluster. This homogeneous distribution requires that most of the metal enrichment of the intergalactic medium occurred before the cluster formed, probably more than ten billion years ago, during the period of maximal star formation and black hole activity. PMID:24172976

Werner, Norbert; Urban, Ondrej; Simionescu, Aurora; Allen, Steven W

2013-10-31

57

UV Confirmation of New Quasar Sightlines Suitable for the Study of Intergalactic Helium  

NASA Astrophysics Data System (ADS)

The reionization of intergalactic helium is thought to have occurred between redshifts of about 3 and 4. The study of HeII Lyman-alpha absorption towards a half-dozen quasars at 2.72.9 SDSS quasars, but with special emphasis on extending helium studies to the highest redshift sightlines. Our proposed approach has already proven successful, and additional sightlines will enable follow-up spectal observations to measure the spectrum and evolution of the ionizing background radiation, the density of intergalactic baryons, and the epoch of reionization of the IGM.

Anderson, Scott

2004-07-01

58

On Modeling and Measuring the Temperature of the z ~ 5 Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The temperature of the low-density intergalactic medium (IGM) at high redshift is sensitive to the timing and nature of hydrogen and He II reionization, and can be measured from Lyman-alpha (Ly?) forest absorption spectra. Since the memory of intergalactic gas to heating during reionization gradually fades, measurements as close as possible to reionization are desirable. In addition, measuring the IGM temperature at sufficiently high redshifts should help to isolate the effects of hydrogen reionization since He II reionization starts later, at lower redshift. Motivated by this, we model the IGM temperature at z >~ 5 using semi-numeric models of patchy reionization. We construct mock Ly? forest spectra from these models and consider their observable implications. We find that the small-scale structure in the Ly? forest is sensitive to the temperature of the IGM even at redshifts where the average absorption in the forest is as high as 90%. We forecast the accuracy at which the z >~ 5 IGM temperature can be measured using existing samples of high resolution quasar spectra, and find that interesting constraints are possible. For example, an early reionization model in which reionization ends at z ~ 10 should be distinguishable—at high statistical significance—from a lower redshift model where reionization completes at z ~ 6. We discuss improvements to our modeling that may be required to robustly interpret future measurements.

Lidz, Adam; Malloy, Matthew

2014-06-01

59

Locating the Warm--Hot Intergalactic Medium in the Simulated Local Universe  

NASA Astrophysics Data System (ADS)

We present an analysis of mock spectral observations of warm-hot intergalactic medium (WHIM) using a constrained simulation of the local universe. The simulated map of oxygen emission lines from local WHIM well reproduces the observed structures traced by galaxies in the real local universe. We further attempt to perform mock observation of the outer parts of the simulated Coma cluster and A3627 adopting the expected performance of DIOS (Diffuse Intergalactic Oxygen Surveyor), which is proposed as a dedicated soft X-ray mission to search for cosmic missing baryons. We find that WHIMs surrounding nearby clusters are detectable with a typical exposure time of one day, and thus constitute realistic and promising targets for DIOS. We also find that an X-ray emitting clump in front of Coma cluster, recently reported in the XMM-Newton observation, has a counterpart in the simulated local universe, and its observed spectrum can be well reproduced in the simulated local universe if the gas temperature is set to the observationally estimated value.

Yoshikawa, Kohji; Dolag, Klaus; Suto, Yasushi; Sasaki, Shin; Yamasaki, Noriko Y.; Ohashi, Takaya; Mitsuda, Kazuhisa; Tawara, Yuzuru; Fujimoto, Ryuichi; Furusho, Tae; Furuzawa, Akihiro; Ishida, Manabu; Ishisaki, Yoshitaka; Takei, Yoh

2004-12-01

60

Space  

NSDL National Science Digital Library

This unit begins by introducing students to the historical motivation for space exploration. They learn about the International Space Station, including current and futuristic ideas that engineers are designing to propel space research. Then they learn about the physical properties of the Moon, and think about what types of products engineers would need to design in order for humans to live on the Moon. Lastly, students learn some descriptive facts about asteroids, such as their sizes and how that relates to the potential danger of an asteroid colliding with the Earth.

Integrated Teaching And Learning Program

61

Cosmic gamma-ray propagation as a probe for intergalactic media and interactions  

NASA Astrophysics Data System (ADS)

Very-high-energy (VHE) gamma rays beyond 100 GeV, coming from galactic and extragalactic sources, reflect the most energetic non-thermal processes in the universe. The emission of these photons indicates the acceleration of charged particles to very high energies or the existence of exotic particles that annihilate or decay to photons. Observations of VHE gamma rays probing this highest energy window of electromagnetic waves thus can reveal the underlying acceleration processes or new astrophysical particles. The fluxes tend to be power-law spectra and this poses a difficulty for direct observation due to the low flux at the high-energy end and to the limited effective area of space-borne instruments. Ground-based VHE gamma-ray observatories therefore take advantage of the earth atmosphere as a calorimeter and observe the gamma rays indirectly via the electromagnetic cascade shower particles they produce. The shower particles are detected either directly or via the Cherenkov radiation they emit while propagating through the air. The current-generation telescopes adopting this ground-based methodology have confirmed several source categories and are starting to answer various physical and astronomical questions, e.g., the origin of cosmic rays, the nature of dark matter, the black hole accretion processes, etc. Together with multi-wavelength observations covering the full electromagnetic spectrum and astrophysical observatories of other particles (cosmic rays, neutrinos, etc.) VHE gamma-ray astronomy contributes as an indispensable part of the recently emerging field of multi-messenger particle astrophysics. When emitted by extragalactic sources, the VHE gamma rays undergo various interactions in the intergalactic medium as they propagate toward the earth. There is a guaranteed interaction, where the VHE gamma-ray photons are absorbed by the extragalactic background light (EBL), an isotropic background of optical-to-infrared photons coming from starlight or dust re-emission in the universe, producing electron-positron pairs. The pairs then upscatter ambient EBL and cosmic microwave background (CMB) photons to gamma rays, which are mostly high-energy (HE), i.e., between 100 MeV and 100 GeV. These secondary gamma rays could also trigger further pair production processes, resulting in an electromagnetic cascade in the cosmic voids. When there is no magnetic field present, all of the cascade gamma rays travel in virtually the same direction as the primary emissions from the source, adding to the observed gamma-ray flux. If the magnetic field in the voids is not negligible, however, the electron-positron pairs are deflected prior to inverse-Compton (IC) scattering on the background photons, impacting to the cascade photons an angular extension. The angular extension caused by the magnetic field both decreases the directly-observed source flux and creates a gamma-ray halo around the original source. An observation of the gamma-ray halo would therefore present a detection of the cosmic magnetic field, which so far has only upper limits imposed from Faraday rotation measurements of radio galaxies. On the other hand, by placing an upper limit on the HE gamma-ray flux of the source we can also derive a lower limit on the magnetic field. To address the processes involved in VHE gamma-ray propagation, I employ both semi-analytic models and full-scale Monte Carlo simulations derived from first principles. The two ways of approach give complementary perspectives on the physics involved and cross-check with each other to ensure a reliable result. By fitting the predicted cascade flux with observed data in both VHE and HE energy ranges by ground-based imaging atmospheric Cherenkov telescopes (IACTs) and the Fermi Large Area Telescope (LAT), I can place a robust lower limit on the extragalactic magnetic field (EGMF) strength at 10--16 to 10--15 Gauss, or at 10 --18 to 10--17 Gauss for a more conservative assumption on the source livetime. The lower limit rules out a large portion of the parameter space for the magnetic field cosmogenic mo

Huan, Hao

2012-05-01

62

Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-Ray Background  

NASA Technical Reports Server (NTRS)

The intergalactic magnetic field (IGMF) may leave an imprint on the anisotropy properties of the extragalactic gamma-ray background, through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thus inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that the two extreme cases (zero IGMF and IGMF strong enough to completely isotropize cascade photons) would be separable by ten years of Fermi observations and reasonable model parameters for the gamma-ray background. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

Venters, T. M.; Pavlidou, V.

2012-01-01

63

X-Ray Flux from the Warm-Hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The number of detected baryons in the universe at z<0.5 is much smaller than predicted by standard big bang nucleosynthesis and by the detailed observation of the Ly? forest at redshift z=2. Hydrodynamic simulations indicate that a large fraction of the baryons is expected to be in a ``warm-hot'' (105-107 K) filamentary gas, distributed in the intergalactic medium. This gas, if it exists, should be observable only in the soft X-ray and UV bands. Using the predictions of a particular hydrodynamic model, we simulated the X-ray flux as a function of energy in the 0.1-2 keV band due to the warm-hot intergalactic medium (WHIM) and compared it with the flux from other diffuse components. Our results show that as much as 20% of the total diffuse X-ray background (DXB) in the energy range 0.37-0.925 keV could be due to X-rays from the WHIM, 70% of which from filaments at redshift between 0.1 and 0.6. Simulations done using a FOV of 3' show that in more than 20% of the observations we expect the WHIM flux to contribute to more than 20% of the DXB. These simulations also show that in about 10% of all the observations a single bright filament in the FOV accounts alone for more than 20% of the DXB flux. Redshifted oxygen lines should be clearly visible in these observations. We also investigate the expected angular distribution of the X-ray flux from the WHIM and found a characteristics angular scale of a few arcminutes.

Ursino, E.; Galeazzi, M.

2006-12-01

64

The proximity profile of intergalactic He II resonance absorption toward high-redshift QSOs  

NASA Technical Reports Server (NTRS)

The Gunn-Peterson effect predicts that an absorption trough should be associated with any resonance line arising in the intergalactic medium (IGM), extending blueward of the line in the QSO's rest frame. We show that such an absorption trough will not generally have a sharp edge at the QSO's redshift but should develop gradually toward shorter wavelengths. This proximity profile of the Gunn-Peterson trough arises because diffuse intergalactic gas in the vicinity of the QSO is more highly ionized than the general IGM. We consider the case of a uniform IGM in approximate photoionization equilibrium with a metagalactic UV background and investigate the proximity profile of He II lambda 304, which might be observable in QSOs with Z(sub Q) approximately 3. Assuming the QSO continuum extends beyond the He II ionization edge, the proximity profile has a characteristic width of delta z(sub p) = delta lambda/304 is approximately 0.1 f is the QSO Lyman limit luminosity in units of 10(exp 31) ergs/s/Hz averaged over the past approximately 10(exp 7) yr, omega(sub I) is the IGM density near (is less than or equal to 10 Mpc) the QSO, omega(sub b) is the normalized baryon density predicted by standard big band necleosynthesis, and f is a factor of order unity which depends weakly on several other factors. Application of this result to the reported detection of the He II Gunn-Peterson effect in Q0302-003 (Jakobsen et al. 1994) suggests that omega(sub I) is approximately equal to omega(sub b), some three orders of magnitude larger than the minimum density that may be inferred from application of the ordinary Gunn-Peterson effect to this QSO. Future observations of the He II proximity profile at higher resolution and signal-to-noise ratio in serveral ASOs should provide the means to measure the IGM density accurately.

Zheng, Wei; Davidsen, Arthur

1995-01-01

65

Measuring the correlation length of intergalactic magnetic fields from observations of gamma-ray induced cascades  

NASA Astrophysics Data System (ADS)

Context. The imaging and timing properties of ?-ray emission from electromagnetic cascades initiated by very-high-energy (VHE) ?-rays in the intergalactic medium depend on the strength B and correlation length ?B of intergalactic magnetic fields (IGMF). Aims: We study the possibility of measuring both B and ?B via observations of the cascade emission with ?-ray telescopes. Methods: For each measurement method, we find two characteristics of the cascade signal, which are sensitive to the IGMF B and ?B values in different combinations. For the case of IGMF measurement using the observation of extended emission around extragalactic VHE ?-ray sources, the two characteristics are the slope of the surface brightness profile and the overall size of the cascade source. For the case of IGMF measurement from the time delayed emission, these two characteristics are the initial slope of the cascade emission light curve and the overall duration of the cascade signal. Results: We show that measurement of the slope of the cascade induced extended emission and/or light curve can both potentially provide measure of the IGMF correlation length, provided it lies within the range 10 kpc ? ?B ? 1 Mpc. For correlation lengths outside this range, gamma-ray observations can provide an upper or lower bound on ?B. The latter of the two methods holds great promise in the near future for providing a measurement/constraint using measurements from present/next-generation ?-ray-telescopes. Conclusions: Measurement of the IGMF correlation length will provide an important constraint on its origin. In particular, it will enable to distinguish between an IGMF of galactic wind origin from an IGMF of cosmological origin.

Neronov, A.; Taylor, A. M.; Tchernin, C.; Vovk, I.

2013-06-01

66

Space.  

ERIC Educational Resources Information Center

This annotated subject guide to Web sites and additional resources focuses on space and astronomy. Specifies age levels for resources that include Web sites, CD-ROMS and software, videos, books, audios, and magazines; offers professional resources; and presents a relevant class activity. (LRW)

Web Feet K-8, 2001

2001-01-01

67

The Column Density Distribution and Continuum Opacity of the Intergalactic and Circumgalactic Medium at Redshift langzrang = 2.4  

NASA Astrophysics Data System (ADS)

We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at langzrang = 2.4. Using Voigt profile fits to the full Ly? and Ly? forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14 \\lesssim log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\lesssim 17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than in the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N H I absorbers than low-N H I absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\gt 17.2 requires a broken power law parameterization of the frequency distribution with a break near N H I ?1015 cm-2. We compute new estimates of the mean free path (?mfp) to hydrogen-ionizing photons at z em = 2.4, finding ?mfp = 147 ± 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to ?mfp = 121 ± 15 Mpc. These ?mfp measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z ? 2-3. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation.

Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.; Pettini, Max

2013-06-01

68

Diagnosing the reionization of the universe - The absorption spectrum of the intergalactic medium and Lyman alpha clouds  

NASA Technical Reports Server (NTRS)

The thermal and ionization evolution of a uniform intergalactic medium composed of H and He and undergoing reionization is studied. The diagnosis of the metagalactic ionizing radiation background at z of about three using metal line ratios for Lyman limit quasar absorption line systems is addressed. The use of the He II Gunn-Peterson effect to diagnose the reionization source and/or nature of the Hy-alpha forest clouds is considered.

Giroux, Mark L.; Shapiro, Paul R.

1991-01-01

69

The intergalactic medium over the last 10 billion years - I. Ly? absorption and physical conditions  

NASA Astrophysics Data System (ADS)

The intergalactic medium (IGM) is the dominant reservoir of baryons at all cosmic epochs. In this paper, we investigate the evolution of the IGM from z = 2 -> 0 in (48h-1Mpc)3, 110-million particle cosmological hydrodynamic simulations using three prescriptions for galactic outflows. We focus on the evolution of IGM physical properties, and how such properties are traced by Ly? absorption as detectable using Hubble's Cosmic Origins Spectrograph (COS). Our results broadly confirm the canonical picture that most Ly? absorbers arise from highly ionized gas tracing filamentary large-scale structure. Growth of structure causes gas to move from the diffuse photoionized IGM into other cosmic phases, namely stars, cold and hot gas within galaxy haloes, and the unbound and shock-heated warm-hot intergalactic medium (WHIM). By today, baryons are comparably divided between bound phases (35 per cent in our favoured outflow model), the diffuse IGM (41 per cent) and the WHIM (24 per cent). Here we (re)define the WHIM as gas with overdensities lower than that in haloes ( today) and temperatures T > 105 K, to more closely align it with the `missing baryons' that are not easily detectable in emission or Ly? absorption. Strong galactic outflows can have a noticeable impact on the temperature of the IGM, though with our favoured momentum-driven wind scalings they do not. When we (mildly) tune our assumed photoionizing background to match the observed evolution of the Ly? mean flux decrement, we obtain line count evolution statistics that broadly agree with available (pre-COS) observations. We predict a column density distribution slope of for our favoured wind model, in agreement with recent observational estimates, and it becomes shallower with redshift. Winds have a mostly minimal impact, but they do result in a shallower column density slope and more strong lines. With improved statistics, the frequency of strong lines can be a valuable diagnostic of outflows, and the momentum-driven wind model matches existing data significantly better than the two alternatives we consider. The relationship between column density and physical density broadens mildly from z = 2 -> 0, and evolves as for diffuse absorbers, consistent with previous studies. Linewidth distributions are quite sensitive to spectral resolution; COS should yield significantly broader lines than higher resolution data. Thermal contributions to linewidths are typically subdominant, so linewidths only loosely reflect the temperature of the absorbing gas. This will hamper attempts to quantify the WHIM using broad Ly? absorbers, though it may still be possible to do so statistically. Together, COS data and simulations such as these will provide key insights into the physical conditions of the dominant reservoir of baryons over the majority of cosmic time.

Davé, Romeel; Oppenheimer, Benjamin D.; Katz, Neal; Kollmeier, Juna A.; Weinberg, David H.

2010-11-01

70

Star Formation Feedback and Metal-enrichment History of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Using the state-of-the-art cosmological hydrodynamic simulations of the standard cold dark matter model with star formation feedback strength normalized to match the observed star formation history of the universe at z= 0-6, we compute the metal-enrichment history of the intergalactic medium (IGM). Overall we show that galactic superwind (GSW) feedback from star formation can transport metals to the IGM and that the properties of simulated metal absorbers match current observations. The distance of influence of GSW from galaxies is typically limited to about <=0.5 Mpc and within regions of overdensity ? >= 10. Most C IV and O VI absorbers are located within shocked regions of elevated temperature (T >= 2 × 104 K), overdensity (? >= 10), and metallicity ([Z/ Z sun] = [ - 2.5, - 0.5]), enclosed by double shocks propagating outward. O VI absorbers have typically higher metallicity, lower density, and higher temperature than C IV absorbers. For O VI absorbers, collisional ionization dominates over the entire redshift range z= 0-6, whereas for C IV absorbers the transition occurs at moderate redshift z ~ 3 from collisionally dominated to photoionization dominated. We find that the observed column density distributions for C IV and O VI in the range log N cm2=12-15 are reasonably reproduced by the simulations. The evolution of mass densities contained in C IV and O VI lines, ?C IV and ?O VI , is also in good agreement with observations, which shows a near constancy at low redshifts and an exponential drop beyond redshift z= 3-4. For both C IV and O VI, most absorbers are transient and the amount of metals probed by C IV and O VI lines of column log N cm2=12-15 is only ~2% of total metal density at any epoch. While gravitational shocks from large-scale structure formation dominate the energy budget (80%-90%) for turning about 50% of the IGM to the warm-hot intergalactic medium (WHIM) by z = 0, GSW feedback shocks are energetically dominant over gravitational shocks at z>=1-2. Most of the so-called missing metals at z= 2-3 are hidden in a warm-hot (T = 104.5-107 K) gaseous phase, heated up by GSW feedback shocks. Their mass distribution is broadly peaked at ?=1-10 in the IGM, outside virialized halos. Approximately 37%, 46%, 10%, and 7% of the total metals at z = 0 are in stars, WHIM, X-ray gas, and cold gas, respectively; the distributions stand at 23%, 57%, 2%, and 18% and 14%, 51%, 4%, and 31% at z = 2 and z = 4, respectively.

Cen, Renyue; Chisari, Nora Elisa

2011-04-01

71

Doubling the Data on the HeII Re-ionization of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

We propose to double the existing information on the ionization of HeII in the IGM at redshifts around 3. We will observe 3 QSOs that are bright in the far UV. Each will give a moderate resolution HST spectrum better than any obtained so far. We will also observe a fourth QSO that currently lacks high SNR spectra. This program addresses a central issue in cosmology: the reionization of the intergalactic medium {IGM}. Current theoretical models predict that H I starts to reionize around z=17, completing near 6, while HeII reionization is delayed until z=3. The theoretical models of the ionization of HeII in the IGM now offer more detailed predictions that the data can distinguish. The new spectra will provide the data required to distinguish between different reionization scenarios, by increasing the number of lines of sight near z=3 with good spectra from 3 to 7, 3 of which will have the best sensitivity to the HeII optical depth. For the first time we also explore the 3-dimensional distribution of the ionizing regions, to characterize the luminosity and number density of the ionizing sources.

Tytler, David

2004-07-01

72

Cosmic gamma-ray background from structure formation in the intergalactic medium  

PubMed

The Universe is filled with a diffuse background of gamma-ray radiation, the origin of which remains one of the unsolved puzzles of cosmology. Less than one-quarter of the gamma-ray flux can be attributed to unresolved discrete sources, such as active galactic nuclei; the remainder appears to constitute a truly diffuse background. Here we show that the shock waves induced by gravity in the gas of the intergalactic medium, during the formation of large-scale structures like filaments and sheets of galaxies, produce a population of highly relativistic electrons. These electrons scatter a small fraction of the cosmic microwave background photons in the local Universe up to gamma-ray energies, thereby providing the gamma-ray background. The predicted diffuse flux agrees with the observed background across more than four orders of magnitude in photon energy, and the model predicts that the gamma-ray background, though generated locally, is isotropic to better than five per cent on angular scales larger than a degree. Moreover, the agreement between the predicted and observed background fluxes implies a mean cosmological density of baryons that is consistent with Big Bang nucleosynthesis. PMID:10821264

Loeb; Waxman

2000-05-11

73

Non-parametric 3D map of the intergalactic medium using the Lyman-alpha forest  

NASA Astrophysics Data System (ADS)

Visualizing the high-redshift Universe is difficult due to the dearth of available data; however, the Lyman-alpha forest provides a means to map the intergalactic medium at redshifts not accessible to large galaxy surveys. Large-scale structure surveys, such as the Baryon Oscillation Spectroscopic Survey (BOSS), have collected quasar (QSO) spectra that enable the reconstruction of H I density fluctuations. The data fall on a collection of lines defined by the lines of sight (LOS) of the QSO, and a major issue with producing a 3D reconstruction is determining how to model the regions between the LOS. We present a method that produces a 3D map of this relatively uncharted portion of the Universe by employing local polynomial smoothing, a non-parametric methodology. The performance of the method is analysed on simulated data that mimics the varying number of LOS expected in real data, and then is applied to a sample region selected from BOSS. Evaluation of the reconstruction is assessed by considering various features of the predicted 3D maps including visual comparison of slices, probability density functions (PDFs), counts of local minima and maxima, and standardized correlation functions. This 3D reconstruction allows for an initial investigation of the topology of this portion of the Universe using persistent homology.

Cisewski, Jessi; Croft, Rupert A. C.; Freeman, Peter E.; Genovese, Christopher R.; Khandai, Nishikanta; Ozbek, Melih; Wasserman, Larry

2014-05-01

74

X-Ray and Sunyaev-Zel'dovich Properties of the Warm-hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

We use numerical simulations to predict the soft X-ray ([0.4-0.6] keV) and Sunyaev-Zel'dovich (SZ) signal (at 150 GHz) from a large-scale structure in the universe and then compute two-point statistics to study the spatial distribution and time evolution of the signals. The average X-ray signal predicted for the warm-hot intergalactic medium (WHIM) is in good agreement with observational constraints that set it at about 10% of the total diffuse X-ray background. The characteristic angle computed with the autocorrelation function is of the order of some arcminutes and becomes smaller at higher redshift. The power spectrum peak of the SZ due to the WHIM is at l ~ 10,000 and has an amplitude of ~0.2 ?K2, about one order of magnitude below the signal measured with telescopes like Planck, Atacama Cosmology Telescope, and South Pole Telescope. Even if the high-redshift WHIM signal is too weak to be detected using X-rays only, the small-scale correlation between X-ray and SZ maps is dominated by the high-redshift WHIM. This makes the analysis of the SZ signal in support of X-rays a promising tool to study the early time WHIM.

Ursino, E.; Galeazzi, M.; Huffenberger, K.

2014-07-01

75

The evolving intergalactic medium - The uncollapsed baryon fraction in a cold dark matter universe  

NASA Technical Reports Server (NTRS)

The time-varying density of the intergalactic medium (IGM) is calculated by coupling detailed numerical calculations of the thermal and ionization balance and radiative transfer in a uniform IGM of H and He to the linearized equations for the growth of density fluctuations in both gases and a dark component in a cold dark matter universe. The IGM density is identified with the collapsed baryon fraction. It is found that even if the IGM is never reheated, a significant fraction of the baryons remain uncollapsed at redshifts of four. If instead the collapsed fraction releases enough ionizing radiation or thermal energy to reionize the IGM by z greater than four as required by the Gunn-Peterson (GP) constraint, the uncollapsed fraction at z of four is even higher. The known quasar distribution is insufficient to supply the ionizing radiation necessary to satisfy the GP constraint in this case and, if stars are instead responsible, a substantial metallicity must have been produced by z of four.

Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

1991-01-01

76

MAST Interface to Synthetic Telescopes with yt {MISTY}: Observing Simulations of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The COS instrument has shed new light on the metal-rich, massive, multi-phase reservoirs of gas surrounding galaxies. Numerical modeling has greatly enhanced the scientific understanding of the large body of of circumgalactic medium {CGM} and intergalactic medium {IGM} observations taken with COS. These numerical models produce synthetic spectra for direct comparison against COS outputs, a useful data resource for both simulators and observers alike, yet different groups apply different methods and formats, and there is no public archive of this scientific resource. We propose to construct a uniform and public simulation-to-archive pipeline for generating, analyzing, and providing to the community such synthetic spectra. By enabling rigorous and consistent comparisons between COS data and simulations, this project will advance our detailed knowledge of the physical and chemical conditions in CGM/IGM absorbers {density, temperature, metallicity ionization, ionization process}, and of the connection between observed velocity structure and galactic inflows and outflows. The results of our pipeline will be searchable via a MAST interface allowing users to specify subsets of synthetic spectra they wish to download and analyze.;

Peeples, Molly

2013-07-01

77

FARADAY ROTATION MEASURE DUE TO THE INTERGALACTIC MAGNETIC FIELD. II. THE COSMOLOGICAL CONTRIBUTION  

SciTech Connect

We investigate the Faraday rotation measure (RM) due to the intergalactic magnetic field (IGMF) through the cosmic web up to cosmological distances, using a model IGMF based on turbulence dynamo in the large-scale structure of the universe. By stacking the IGMF and gas density data up to redshift z = 5 and taking account of the redshift distribution of polarized background radio sources against which the RM is measured, we simulate the sky map of the RM. The contribution from galaxy clusters is subtracted from the map, based on several different criteria of X-ray brightness and temperature. Our findings are as follows. The distribution of RM for radio sources of different redshifts shows that the rms value increases with redshift and saturates for z {approx}> 1. The saturated value is RM{sub rms} {approx} several rad m{sup -2}. The probability distribution function of |RM| follows the lognormal distribution. The power spectrum has a broad plateau over the angular scale of {approx}1{sup 0}-0.{sup 0}1 with a peak around {approx}0.{sup 0}15. The second-order structure function has a flat profile in the angular separation of {approx}> 0.{sup 0}2. Our results could provide useful insights for surveys to explore the IGMF with the Square Kilometer Array (SKA) and upcoming SKA pathfinders.

Akahori, Takuya [Research Institute of Basic Science, Chungnam National University, Daejeon (Korea, Republic of); Ryu, Dongsu, E-mail: akataku@canopus.cnu.ac.kr, E-mail: ryu@canopus.cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2011-09-10

78

Future evolution of the intergalactic medium in a universe dominated by a cosmological constant  

NASA Astrophysics Data System (ADS)

We simulate the evolution of the intergalactic medium (IGM) in a universe dominated by a cosmological constant. We find that within a few Hubble times from the present epoch, the baryons will have two primary phases: one phase composed of low-density, low-temperature, diffuse, ionized gas which cools rapidly with cosmic time due to adiabatic exponential expansion, and a second phase of high-density, high-temperature gas in virialized dark matter halos which cools much more slowly by atomic processes. The mass fraction of gas in halos converges to ˜40% at late times, about twice its calculated value at the present epoch. We find that in a few Hubble times, the large scale filaments in the present-day IGM will rarefy and fade away into the low-temperature IGM, and only islands of virialized gas will maintain their physical structure. We do not find evidence for fragmentation of the diffuse IGM at later times. More than 99% of the gas mass will maintain a steady ionization fraction above 80% within a few Hubble times. The diffuse IGM will get extremely cold and dilute but remain highly ionized, as its recombination time will dramatically exceed the age of the universe.

Nagamine, Kentaro; Loeb, Abraham

2004-10-01

79

Measurement of Intergalactic Magnetic and Photon Fields with Secondary Photons and Neutrinos  

NASA Astrophysics Data System (ADS)

Active galactic nuclei (AGN) can produce both gamma rays and cosmic rays. The observed high-energy gamma-ray signals from distant blazars may be dominated by secondary gamma rays produced along the line of sight by the interactions of cosmic-ray protons and gamma rays with background photons. This explains the surprisingly low attenuation observed for distant blazars, because the production of secondary gamma rays occurs, on average, much closer to Earth than the distance to the source. Thus the observed spectrum in the TeV range depends on the combination of secondary and primary signals. We apply this hypothesis to a number of sources and, in every case, we obtain an excellent fit, strengthening the interpretation of the observed spectra as being due to secondary gamma rays. We explore the ramifications of this interpretation for limits on the intergalactic magnetics fields, extragalactic background light and AGN properties. We also make predictions for the neutrino signals, which can help probe the acceleration of cosmic rays in AGN.

Essey, Warren James

80

X-Ray Absorption by the Warm-hot Intergalactic Medium in the Hercules Supercluster  

NASA Astrophysics Data System (ADS)

"Missing baryons," in the form of warm-hot intergalactic medium (WHIM), are expected to reside in cosmic filamentary structures that can be traced by signposts such as large-scale galaxy superstructures. The clear detection of an X-ray absorption line in the Sculptor Wall demonstrated the success of using galaxy superstructures as a signpost to search for the WHIM. Here we present an XMM -Newton Reflection Grating Spectrometer observation of the blazar Mkn 501, located in the Hercules Supercluster. We detected an O VII K? absorption line at the 98.7% level (2.5?) at the redshift of the foreground Hercules Supercluster. The derived properties of the absorber are consistent with theoretical expectations of the WHIM. We discuss the implication of our detection for the search for the "missing baryons." While this detection shows again that using signposts is a very effective strategy to search for the WHIM, follow-up observations are crucial both to strengthen the statistical significance of the detection and to rule out other interpretations. A local, z ~ 0 O VII K? absorption line was also clearly detected at the 4? level, and we discuss its implications for our understanding of the hot gas content of our Galaxy.

Ren, Bin; Fang, Taotao; Buote, David A.

2014-02-01

81

Scale-dependent bias in the baryonic-acoustic-oscillation-scale intergalactic neutral hydrogen  

NASA Astrophysics Data System (ADS)

I discuss fluctuations in the neutral hydrogen density of the z?2.3 intergalactic medium and show that their relation to cosmic overdensity is strongly scale dependent. This behavior arises from a linearized version of the well-known "proximity effect," in which bright sources suppress atomic hydrogen density. Using a novel, systematic and detailed linear-theory radiative-transfer calculation, I demonstrate how Hi density consequently anticorrelates with total matter density when averaged on scales exceeding the Lyman-limit mean-free path. The radiative-transfer thumbprint is highly distinctive and should be measurable in the Lyman-? forest. Effects extend to sufficiently small scales to generate significant distortion of the correlation function shape around the baryon acoustic oscillation peak, although the peak location shifts only by 1.2 percent for a mean source bias of bj=3. The distortion changes significantly with bj and other astrophysical parameters; measuring it should provide a helpful observational constraint on the nature of ionizing photon sources in the near future.

Pontzen, Andrew

2014-04-01

82

Characterizing the Low-Redshift Intergalactic Medium toward PKS 1302-102  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of the intergalactic metal-line absorption systems in the archival HST STIS and FUSE ultraviolet spectra of the low-redshift quasar PKS 1302-102 (zQSO=0.2784). We supplement the archive data with CLOUDY ionization models and a survey of galaxies in the quasar field. There are 15 strong Ly? absorbers with column densities logNHI>14. Of these, six are associated with at least C III ?977 absorption [logN(C++)>13] this implies a redshift density dNCIII/dz=36+13-9 (68% confidence limits) for the five detections with rest equivalent width Wr>50 mÅ. Two systems show O VI ??1031, 1037 absorption in addition to C III [logN(O+5)>14]. One is a partial Lyman limit system (logNHI=17) with associated C III, O VI, and Si III ?1206 absorption. There are three tentative O VI systems that do not have C III detected. For one O VI doublet with both lines detected at 3 ? with Wr>50 mÅ, dNOVI/dz=7+9-4. We also search for O VI doublets without Ly? absorption but identify none. From CLOUDY modeling, these metal-line systems have metallicities spanning the range -4<~[M/H]<~-0.3. The two O VI systems with associated C III absorption cannot be single-phase, collisionally ionized media based on the relative abundances of the metals and kinematic arguments. From the galaxy survey, we discover that the absorption systems are in a diverse set of galactic environments. Each metal-line system has at least one galaxy within 500 km s-1 and 600 h-175 kpc with L>0.1L*.

Cooksey, Kathy L.; Prochaska, Jason X.; Chen, Hsiao-Wen; Mulchaey, John S.; Weiner, Benjamin J.

2008-03-01

83

Cosmological Simulations of Intergalactic Medium Evolution. I. Test of the Subgrid Chemical Enrichment Model  

NASA Astrophysics Data System (ADS)

We present a one-zone galactic chemical enrichment model that takes into account the contribution of stellar winds from massive stars under the effect of rotation, Type II supernovae, hypernovae, stellar winds from low- and intermediate-mass stars, and Type Ia supernovae. This enrichment model will be implemented in a galactic model designed to be used as a subgrid treatment for galaxy evolution and outflow generation in large-scale cosmological simulations, in order to study the evolution of the intergalactic medium. We test our enrichment prescription by comparing its predictions with the metallicity distribution function and the abundance patterns of 14 chemical elements observed in the Milky Way stars. To do so, we combine the effect of many stellar populations created from the star formation history of the Galaxy in the solar neighborhood. For each stellar population, we keep track of its specific mass, initial metallicity, and age. We follow the time evolution of every population in order to respect the time delay between the various stellar phases. Our model is able to reproduce the observed abundances of C, O, Na, Mg, Al, S, and Ca. For Si, Cr, Mn, Ni, Cu, and Zn, the fits are still reasonable, but improvements are needed. We marginally reproduce the nitrogen abundance in very low metallicity stars. Overall, our results are consistent with the predicted abundance ratios seen in previous studies of the enrichment history of the Milky Way. We have demonstrated that our semi-analytic one-zone model, which cannot deal with spatial information such as the metallicity gradient, can nevertheless successfully reproduce the global Galactic enrichment evolution obtained by more complex models, at a fraction of the computational cost. This model is therefore suitable for a subgrid treatment of chemical enrichment in large-scale cosmological simulations.

Côté, Benoit; Martel, Hugo; Drissen, Laurent

2013-11-01

84

THE STATE OF STAR FORMATION AND THE INTERGALACTIC MEDIUM AT z {approx} 6  

SciTech Connect

In the context of stellar reionization in the standard cold dark matter model, we analyze observations at z {approx} 6 and are able to draw three significant conclusions with respect to star formation and the state of the intergalactic medium (IGM) at z {approx} 6. (1) An initial stellar mass function (IMF) more efficient, by a factor of 10-20, in producing ionizing photons than the standard Salpeter IMF is required at z {approx} 6. This may be achieved by having either (a) a metal-enriched IMF with a lower mass cutoff of {>=}30 M{sub sun} or (b) 2%-4% of stellar mass being Population III massive metal-free stars at z {approx} 6. While there is no compelling physical reason or observational evidence to support (a), (b) could plausibly be fulfilled by continued existence of some pockets of uncontaminated, metal-free gas for star formation. (2) The volume-weighted neutral fraction of the IGM of {sub V}{approx}10{sup -4} at z = 5.8 inferred from the SDSS observations of QSO absorption spectra provides enough information to ascertain that reionization is basically complete with at most {approx}0.1%-1% of IGM that is unionized at z = 5.8. (3) Barring some extreme evolution of the IMF, the neutral fraction of the IGM is expected to rise quickly toward high redshift from the point of H II bubble percolation, with the mean neutral fraction of the IGM expected to reach 6%-12% at z = 6.5, 13%-27% at z = 7.7, and 22%-38% at z = 8.8.

Cen Renyue, E-mail: cen@astro.princeton.ed [Princeton University Observatory, Princeton, NJ 08544 (United States)

2010-12-10

85

Effect of intergalactic medium on the observability of Ly? emitters during cosmic reionization  

NASA Astrophysics Data System (ADS)

We perform a systematic study of how the inhomogeneities in the intergalactic medium (IGM) affect the observability of Ly? emitters (LAEs) around the epoch of reionization. We focus on the IGM close to the galaxies as the detailed ionization distribution and velocity fields of this region could significantly influence the scattering of Ly? photons off neutral H atoms as they traverse the IGM after escaping from the galaxy. We simulate the surface brightness (SB) maps and spectra of more than 100 LAEs at z = 7.7 as seen by an observer at z = 0. To achieve this, we extract the source properties of galaxies and their surrounding IGM from cosmological simulations of box sizes 5-30 h-1 Mpc and then follow the coupled radiative transfer of ionizing and Ly? radiation through the IGM using CRASH?. We find that the simulated SB profiles are extended and their detailed structure is affected by inhomogeneities in the IGM, especially at high neutral fractions. The detectability of LAEs and the fraction of the flux observed depend heavily on the shape of the SB profile and the SB threshold (SB th) of the observational campaign. Only ultradeep observations (e.g. SBth˜10-23 erg s-1 cm-2 arcsec-2) would be able to obtain the true underlying mass-luminosity relation and luminosity functions of LAEs. The details of our results depend on whether Ly? photons are significantly shifted in the galaxy to longer wavelengths, the mean ionization fraction in the IGM and the clustering of ionizing sources. These effects can lead to an easier escape of Ly? photons with less scattering in the IGM and a concentrated SB profile, similar to the one of a point source. Finally, we show that the SB profiles are steeper at high-ionization fraction for the same LAE sample which can potentially be observed from the stacked profile of a large number of LAEs.

Jeeson-Daniel, Akila; Ciardi, Benedetta; Maio, Umberto; Pierleoni, Marco; Dijkstra, Mark; Maselli, Antonella

2012-08-01

86

THE OPACITY OF THE INTERGALACTIC MEDIUM DURING REIONIZATION: RESOLVING SMALL-SCALE STRUCTURE  

SciTech Connect

Early in the reionization process, the intergalactic medium (IGM) would have been quite inhomogeneous on small scales, due to the low Jeans mass in the neutral IGM and the hierarchical growth of structure in a cold dark matter universe. This small-scale structure acted as an important sink during the epoch of reionization, impeding the progress of the ionization fronts that swept out from the first sources of ionizing radiation. Here we present results of high-resolution cosmological hydrodynamics simulations that resolve the cosmological Jeans mass of the neutral IGM in representative volumes several Mpc across. The adiabatic hydrodynamics we follow are appropriate in an unheated IGM, before the gas has had a chance to respond to the photoionization heating. Our focus is determination of the resolution required in cosmological simulations in order to sufficiently sample and resolve small-scale structure regulating the opacity of an unheated IGM. We find that a dark matter particle mass of m {sub dm} {approx}< 50 M {sub Sun} and box size of L {approx}> 1 Mpc are required. With our converged results we show how the mean free path of ionizing radiation and clumping factor of ionized hydrogen depend on the ultraviolet background flux and redshift. We find, for example at z = 10, clumping factors typically of 10-20 for an ionization rate of {Gamma} {approx} (0.3-3) Multiplication-Sign 10{sup -12} s{sup -1}, with corresponding mean free paths of {approx}3-15 Mpc, extending previous work on the evolving mean free path to considerably smaller scales and earlier times.

Emberson, J. D.; Thomas, Rajat M.; Alvarez, Marcelo A., E-mail: emberson@astro.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto, ON M5S 3H8 (Canada)

2013-02-15

87

The Baryon Census in a Multiphase Intergalactic Medium: 30% of the Baryons May Still be Missing  

NASA Astrophysics Data System (ADS)

Although galaxies, groups, and clusters contain ~10% of the baryons, many more reside in the photoionized and shocked-heated intergalactic medium (IGM) and in the circumgalactic medium (CGM). We update the baryon census in the (H I) Ly? forest and warm-hot IGM (WHIM) at 105-6 K traced by O VI ?1032, 1038 absorption. From Enzo cosmological simulations of heating, cooling, and metal transport, we improve the H I and O VI baryon surveys using spatially averaged corrections for metallicity (Z/Z ?) and ionization fractions (f H I , f O VI ). Statistically, the O VI correction product correlates with column density, (Z/Z ?)f O VI ? (0.015)(N O VI /1014 cm-2)0.70, with an N O VI -weighted mean of 0.01, which doubles previous estimates of WHIM baryon content. We also update the Ly? forest contribution to baryon density out to z = 0.4, correcting for the (1 + z)3 increase in absorber density, the (1 + z)4.4 rise in photoionizing background, and cosmological proper length dl/dz. We find substantial baryon fractions in the photoionized Ly? forest (28% ± 11%) and WHIM traced by O VI and broad-Ly? absorbers (25% ± 8%). The collapsed phase (galaxies, groups, clusters, CGM) contains 18% ± 4%, leaving an apparent baryon shortfall of 29% ± 13%. Our simulations suggest that ~15% reside in hotter WHIM (T >= 106 K). Additional baryons could be detected in weaker Ly? and O VI absorbers. Further progress requires higher-precision baryon surveys of weak absorbers, down to minimum column densities N H I >= 1012.0 cm-2, N O VI >= 1012.5 cm-2, N O VII >= 1014.5 cm-2, using high signal-to-noise data from high-resolution UV and X-ray spectrographs.

Shull, J. Michael; Smith, Britton D.; Danforth, Charles W.

2012-11-01

88

A DIRECT MEASUREMENT OF THE INTERGALACTIC MEDIUM OPACITY TO H I IONIZING PHOTONS  

SciTech Connect

We present a new method to directly measure the opacity from H I Lyman limit (LL) absorption kappa{sub LL} along quasar sight lines by the intergalactic medium (IGM). The approach analyzes the average ('stacked') spectrum of an ensemble of quasars at a common redshift to infer the mean free path lambda{sup 912}{sub mfp} to ionizing radiation. We apply this technique to 1800 quasars at z = 3.50-4.34 drawn from the Sloan Digital Sky Survey (SDSS), giving the most precise measurements on kappa{sub LL} at any redshift. From z = 3.6 to 4.3, the opacity increases steadily as expected and is well parameterized by lambda{sup 912}{sub mfp} = lambda{sub 0} - b {sub l}ambda(z - 3.6) with lambda{sub 0} = (48.4 +- 2.1) h{sup -1}{sub 72} Mpc and b{sub l}ambda = (38.0 +- 5.3) h {sup -1}{sub 72} Mpc (proper distance). The relatively high lambda{sup 912} {sub mfp} values indicate that the incidence of systems which dominate kappa{sub LL} evolves less strongly at z > 3 than that of the Lyalpha forest. We infer a mean free path three times higher than some previous estimates, a result which has important implications for the photoionization rate derived from the emissivity of star-forming galaxies and quasars. Finally, our analysis reveals a previously unreported, systematic bias in the SDSS quasar sample related to the survey's color targeting criteria. This bias potentially affects all z approx 3 IGM studies using the SDSS database.

Prochaska, J. Xavier; Worseck, Gabor [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); O'Meara, John M. [Department of Chemistry and Physics, Saint Michael's College, One Winooski Park, Colchester, VT 05439 (United States)

2009-11-10

89

X-Ray Constraints on the Warm-Hot Intergalactic Medium  

NASA Technical Reports Server (NTRS)

Three observational constraints can be placed on a warm-hot intergalactic medium (WHIM) using ROSAT Position Sensitive Proportional Counter (PSPC) pointed and survey data, the emission strength, the energy spectrum, and the fluctuation spectrum. The upper limit to the emission strength of the WHIM is 7.5 +/- 1.0 keV/(s*sq cm*sr*keV) in the 3/4 keV band, an unknown portion of which value may be due to our own Galactic halo. The spectral stape of the WHIM emission can be described as thermal emission with logT = 6.42, although the true spectrum is more likely to come from a range of temperatures. The values of emission strength and spectral shape are in reasonable agreement with hydrodynamical cosmological models. The autocorrelation function in the 0.44 keV < E < 1.21 keV band range, w(theta), for the extragalactic soft X-ray background (SXRB) which includes both the WHIM and contributions due to point sources, is approx. < 0.002 for 10 min < 0 < 20 min in the 3/4 keV band. This value is lower than the Croft et al. (2000) cosmological model by a factor of approx. 5, but is still not inconsistent with cosmological models. It is also found that the normalization of the extragalactic power law component of the soft X-ray background spectrum must be 9.5 +/- 0.9 keV/(s*sq cm*sr*keV) to be consistent with the ROSAT All-Sky Survey.

Kuntz, K. D.; Snowden, S. I.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

2000-01-01

90

Metallicity of the Intergalactic Medium Using Pixel Statistics. II. The Distribution of Metals as Traced by C IV  

NASA Astrophysics Data System (ADS)

We measure the distribution of carbon in the intergalactic medium as a function of redshift z and overdensity ?. Using a hydrodynamical simulation to link the H I absorption to the density and temperature of the absorbing gas, and a model for the UV background radiation, we convert ratios of C IV to H I pixel optical depths into carbon abundances. For the median metallicity this technique was described and tested in Paper I of this series. Here we generalize it to reconstruct the full probability distribution of the carbon abundance and apply it to 19 high-quality quasar absorption spectra. We find that the carbon abundance is spatially highly inhomogeneous and is well described by a lognormal distribution for fixed ? and z. Using data in the range log?=-0.5-1.8 and z=1.8-4.1, and a renormalized version of the 2001 Haardt & Madau model for the UV background radiation from galaxies and quasars, we measure a median metallicity of [C/H]=-3.47+0.07-0.06+0.08+0.09-0.10(z-3)+0.65+0.10-0.14(log?-0.5) and a lognormal scatter of ?([C/H])=0.76+0.05-0.08+0.02+0.08-0.12(z-3)-0.23+0.09-0.07(log?-0.5). Thus, we find significant trends with overdensity but no evidence for evolution. These measurements imply that gas in this density range accounts for a cosmic carbon abundance of [C/H]=-2.80+/-0.13 (?C~2×10-7), with no evidence for evolution. The dominant source of systematic error is the spectral shape of the UV background, with harder spectra yielding higher carbon abundances. While the systematic errors due to uncertainties in the spectral hardness may exceed the quoted statistical errors for ?<10, we stress that UV backgrounds that differ significantly from our fiducial model give unphysical results. The measured lognormal scatter is strictly independent of the spectral shape, provided the background radiation is uniform. We also present measurements of the C III/C IV ratio (which rule out temperatures high enough for collisional ionization to be important for the observed C IV) and of the evolution of the effective Ly? optical depth. Based on public data obtained from the ESO archive of observations from the UVES spectrograph at the VLT, Paranal, Chile and on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The W. M. Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Schaye, Joop; Aguirre, Anthony; Kim, Tae-Sun; Theuns, Tom; Rauch, Michael; Sargent, Wallace L. W.

2003-10-01

91

CONFIRMATION OF X-RAY ABSORPTION BY WARM-HOT INTERGALACTIC MEDIUM IN THE SCULPTOR WALL  

SciTech Connect

In a previous paper, we reported a 3{sigma} detection of an absorption line from the warm-hot intergalactic medium (WHIM) using the Chandra and XMM X-ray grating spectra of the blazar H2356-309, the sight line of which intercepts the Sculptor Wall, a large-scale superstructure of galaxies at z {approx} 0.03. To verify our initial detection, we obtained a deep (500 ks), follow-up exposure of H2356-309 as part of the Cycle-10 Chandra Large Project Program. From a joint analysis of the Cycle-10 and previous (Cycle-8) Chandra grating data we detect the redshifted O VII WHIM line at a significance level of 3.4{sigma}, a substantial improvement over the 1.7{sigma} level reported previously when using only the Cycle-8 data. The significance increases to 4.0{sigma} when the existing XMM grating data are included in the analysis, thus confirming at higher significance the existence of the line at the redshift of the Sculptor Wall with an equivalent width of 28.5 {+-} 10.5 mA (90% confidence). We obtain a 90% lower limit on the O VII column density of 0.8 x 10{sup 16} cm{sup -2} and a 90% upper limit on the Doppler b parameter of 460 km s{sup -1}. Assuming the absorber is uniformly distributed throughout the {approx}15 Mpc portion of the blazar's sight line that intercepts the Sculptor Wall, that the O VII column density is {approx}2 x 10{sup 16} cm{sup -2} (corresponding to b {approx_gt} 150 km {sup -1} where the inferred column density is only weakly dependent on b), and that the oxygen abundance is 0.1 solar, we estimate a baryon over-density of {approx}30 for the WHIM, which is consistent with the peak of the WHIM mass fraction predicted by cosmological simulations. The clear detection of O VII absorption in the Sculptor Wall demonstrates the viability of using current observatories to study WHIM in the X-ray absorption spectra of blazars behind known large-scale structures.

Fang Taotao; Buote, David A.; Humphrey, Philip J.; Gastaldello, Fabio [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Canizares, Claude R. [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Zappacosta, Luca [INAF-Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143 Trieste (Italy); Maiolino, Roberto [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Roma (Italy); Tagliaferri, Gianpiero, E-mail: fangt@uci.ed [INAF-Osservatorio Astronomico di Brera, Via Bianchi, 46, 23807 Merate (Italy)

2010-05-10

92

THE BARYON CENSUS IN A MULTIPHASE INTERGALACTIC MEDIUM: 30% OF THE BARYONS MAY STILL BE MISSING  

SciTech Connect

Although galaxies, groups, and clusters contain {approx}10% of the baryons, many more reside in the photoionized and shocked-heated intergalactic medium (IGM) and in the circumgalactic medium (CGM). We update the baryon census in the (H I) Ly{alpha} forest and warm-hot IGM (WHIM) at 10{sup 5-6} K traced by O VI {lambda}1032, 1038 absorption. From Enzo cosmological simulations of heating, cooling, and metal transport, we improve the H I and O VI baryon surveys using spatially averaged corrections for metallicity (Z/Z {sub Sun }) and ionization fractions (f {sub HI}, f {sub OVI}). Statistically, the O VI correction product correlates with column density, (Z/Z {sub Sun })f {sub OVI} Almost-Equal-To (0.015)(N {sub OVI}/10{sup 14} cm{sup -2}){sup 0.70}, with an N {sub OVI}-weighted mean of 0.01, which doubles previous estimates of WHIM baryon content. We also update the Ly{alpha} forest contribution to baryon density out to z = 0.4, correcting for the (1 + z){sup 3} increase in absorber density, the (1 + z){sup 4.4} rise in photoionizing background, and cosmological proper length dl/dz. We find substantial baryon fractions in the photoionized Ly{alpha} forest (28% {+-} 11%) and WHIM traced by O VI and broad-Ly{alpha} absorbers (25% {+-} 8%). The collapsed phase (galaxies, groups, clusters, CGM) contains 18% {+-} 4%, leaving an apparent baryon shortfall of 29% {+-} 13%. Our simulations suggest that {approx}15% reside in hotter WHIM (T {>=} 10{sup 6} K). Additional baryons could be detected in weaker Ly{alpha} and O VI absorbers. Further progress requires higher-precision baryon surveys of weak absorbers, down to minimum column densities N {sub HI} {>=} 10{sup 12.0} cm{sup -2}, N {sub OVI} {>=} 10{sup 12.5} cm{sup -2}, N {sub OVII} {>=} 10{sup 14.5} cm{sup -2}, using high signal-to-noise data from high-resolution UV and X-ray spectrographs.

Shull, J. Michael; Danforth, Charles W.; Smith, Britton D., E-mail: michael.shull@colorado.edu, E-mail: smit1685@msu.edu, E-mail: charles.danforth@colorado.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

2012-11-01

93

Impact of primordial ultracompact minihaloes on the intergalactic medium and first structure formation  

NASA Astrophysics Data System (ADS)

The effects of dark matter annihilation on the evolution of the intergalactic medium (IGM) in the early Universe will be more important if the dark matter structure is more concentrated. Ultracompact minihaloes (UCMHs), which formed through dark matter accretion on to primordial black holes (PBHs) or an initial dark matter overdensity produced by a primordial density perturbation, provide a new type of compact dark matter structure to ionize and heat the IGM after matter-radiation equality zeq, which is much earlier than the formation of the first cosmological dark halo structure and later the first stars. We show that the dark matter annihilation density contributed by UCMHs can completely dominate over the homogeneous dark matter annihilation background, even for a tiny UCMH fraction fUCMH=?UCMH(zeq)/?DM? 10-15(1 +z)2(m?c2/100 GeV)-2/3 with a standard thermal-relic dark matter annihilation cross-section, and can provide a new gamma-ray background in the early Universe. UCMH annihilation becomes important to IGM evolution for approximately fUCMH > 10-6(m?c2/100 GeV). The IGM ionization fraction xion and gas temperature Tm can be increased from the recombination residual xion˜ 10-4 and adiabatically cooling Tm? (1 +z)2 in the absence of energy injection, to a maximum value of xion˜ 0.1 and Tm˜ 5000 K at z? 10 for the upper bound on UCMH abundance constrained by the cosmic microwave background optical depth. A small fraction of UCMHs are seeded by PBHs. The X-ray emission from gas accretion on to PBHs may totally dominate over dark matter annihilation, and may become the main cosmic ionization source for a PBH abundance fPBH=?PBH/?DM? 10-11 (10-12) with PBH mass MPBH˜ 10-6 M? (102 M?). However, the constraints on gas accretion rate and X-ray absorption by baryon accumulation within UCMHs, together with accretion feedback, show that X-ray emission can only be a promising source much later than UCMH annihilation at z < zm? 1000, where zm depends on the PBH masses, their host UCMHs and the dark matter particles. Also, UCMH radiation including both annihilation and X-ray emission can significantly suppress the low-mass first baryonic structure formation. The effects of UCMH radiation on baryonic structure evolution are quite small as regards the gas temperature after virialization, but more significant in enhancing gas chemical quantities such as the ionization fraction and molecular hydrogen abundance in baryonic objects.

Zhang, Dong

2011-12-01

94

Rest-frame ultraviolet line emission from the intergalactic medium at 2 ? z ? 5  

NASA Astrophysics Data System (ADS)

Rest-frame ultraviolet (UV) emission lines offer the exciting possibility to directly image the gas around high-redshift galaxies with upcoming optical instruments. We use a suite of large, hydrodynamical simulations to predict the nature and detectability of emission lines from the intergalactic medium (IGM) at 2 ? z ? 5. The brightest emission comes from H I Ly? (1216 Å) and the strongest metal line, C III (977), is about an order of magnitude fainter, although H I Ly? may be fainter if the gas is self-shielded to the UV background or if dust is important. The highest surface brightness regions for C IV (1548, 1551), Si III (1207), Si IV (1393, 1403) and O VI (1032, 1038) are fainter than the brightest C III by factors of a few. The N V (1239, 1243) and Ne VIII (770, 780) lines, as well as He II H? (1640), are substantially weaker, but their maximum surface brightnesses still exceed 102 photon s-1 cm-2 sr-1 at z = 2 (for 2-arcsec pixels). Lower ionization lines typically arise in denser and colder gas that produces clumpier emission. The brightest H I Ly? emission arises exclusively in highly overdense gas, but the highest surface brightness emission from high-ionization metal lines traces a much wider range of overdensities. Bright metal-line emission traces gas with temperatures close to the peak of the corresponding emissivity curve. While H I Ly?, He II H?, C III, Si III and Si IV are excellent probes of cold accretion flows and the colder parts of outflows, C IV, N V, O VI and Ne VIII are powerful tracers of the diffuse warm-hot IGM and galactic winds. A comparison of results from simulations with varying physical prescriptions demonstrates that the predictions for the brighter metal-line emission are robust to within factors of a few. Several rest-frame UV emission lines from the high-redshift IGM will become detectable in the near future, possibly starting with the Cosmic Web Imager, which is already operating on Palomar. The Multi Unit Spectroscopic Explorer, which will be commissioned in 2012 on the Very Large Telescope, and the proposed Keck Cosmic Web Imager have the potential to revolutionize studies of the interactions between high-redshift galaxies and their environment.

Bertone, Serena; Schaye, Joop

2012-01-01

95

The significance of the Hansen Ideal space frame  

NASA Astrophysics Data System (ADS)

Known and unknown properties of Hansen Ideal coordinates are summarized. It is shown that the ideal space frame is a general and necessary component of basic celestial mechanics and astrodynamics, as well as of any theory of motion. A typical consequence is the intimate correlation of the Hansen frame with the Lagrange constraint within the method of the variation of the parameters. The use of observations in the ideal frame may allow conclusions on the intergalactic fundamental coordinate system.

Jochim, E. F. M.

2012-10-01

96

Reionization in a cold dark matter universe: The feedback of galaxy formation on the intergalactic medium  

NASA Technical Reports Server (NTRS)

We study the coupled evolution of the intergalactic medium (IGM) and the emerging structure in the universe in the context of the cold dark matter (CDM) model, with a special focus on the consequences of imposing reionization and the Gunn-Peterson constraint as a boundary condition on the model. We have calculated the time-varying density of the IGM by coupling our detailed, numerical calculations of the thermal and ionization balance and radiative transfer in a uniform, spatially averaged IGM of H and He, including the mean opacity of an evolving distribution of gas clumps which correspond to quasar absorption line clouds, to the linearized equations for the growth of density fluctuations in both the gaseous and dark matter components in a CDM universe. We use the linear growth equations to identify the fraction of the gas which must have collapsed out at each epoch, an approach similar in spirit to the so-called Press-Schechter formalism. We identify the IGM density with the uncollapsed baryon fraction. The collapsed fraction is postulated to be a source of energy injection into the IGM, by radiation or bulk hydrodynamical heating (e.g., via shocks) or both, at a rate which is marginally enough to satisfy the Gunn-Peterson constraint at z less than 5. Our results include the following: (1) We find that the IGM in a CDM model must have contained a substantial fraction of the total baryon density of the universe both during and after its reionization epoch. (2) As a result, our previous conclusion that the observed Quasi-Stellar Objects (QSOs) at high redshift are not sufficient to ionize the IGM enough to satisfy the Gunn-Peterson constraint is confirmed. (3) We predict a detectable He II Gunn-Peterson effect at 304(1 + z) A in the spectra of quasars at a range of redshift z greater than or approx. 3, depending on the nature of the sources of IGM reionization. (4) We find, moreover, that a CDM model with high bias parameter b (i.e., b greater than or approx. 2) cannot account for the baryon content of the universe at z approximately 3 observed in quasar absorption line gas unless Omega (sub B) significantly exceeds the maximum value allowed by big bang nucleocynthesis. (5) For a CDM model with bias parameter within the allowed range of (lower) values, the lower limit to Omega(sub B) imposed by big bang nucleosynthesis (Omega(sub B) h(sup 2) greater than or equal to 0.01) combines with our results to yield the minimum IGM density for the CDM fodel. For CDM with b = 1 (Cosmic Background Explorer (COBE) normalization), we find Omega(sub IGM)(sup min) (z approximately 4) approx. equal 0.02-0.03, and Omega(sub IGM)(sup min)(z approximately 0) approx. equal 0.005-0.03, depending upon the nature of the sources of IGM reionization. (6) In general, we find that self-consistent reionization of the IGM by the collapsed baryon fraction has a strong effect on the rate of collapse. (7) As a further example, we show that the feedback effect on the IGM of energy release by the collapsed baryon fraction may explain the slow evolution of the observed comoving QSO number density between z = 5 and z = 2, followed by the sharp decline after z = 2.

Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

1994-01-01

97

The micro-structure of the intergalactic medium - I. The 21 cm signature from dynamical minihaloes  

NASA Astrophysics Data System (ADS)

A unified description is provided for the 21 cm signatures arising from minihaloes against a bright background radio source and against the cosmic microwave background (CMB), within the context of a dynamical collapsing cosmological spherical halo. The effects of gas cooling via radiative atomic and molecular processes and of star formation on setting the maximum mass of the minihaloes giving rise to a 21 cm signal are included. Models are computed both with and without molecular hydrogen formation, allowing for its possible suppression by an ambient ultraviolet radiation field. The spectral signatures and equivalent width distributions are computed for a ?cold dark matter cosmology. The detectability of minihaloes in absorption against bright background radio sources is discussed in the context of future measurements by a Square Kilometre Array (SKA) and the LOw Frequency ARray (LOFAR). The brightness temperature differential relative to the CMB is also computed. Several generic scenarios are considered. For the cosmological parameter constraints from the Wilkinson Microwave Anisotropy Probe (WMAP), in the absence of any form of galactic feedback, the number of systems per unit redshift in absorption against a bright radio source at 8 < z < 10 is dN/dz? 10 for observed equivalent widths exceeding 0.1 kHz. For larger equivalent widths, somewhat fewer systems are predicted at increasing redshifts. The estimated numbers are independent of the presence of star formation in the haloes following molecular hydrogen formation except for rare, high equivalent width systems, which become fewer. LOFAR could plausibly detect a minihalo signal against a 30 mJy source in a 1200 h integration. SKA could detect the signal against a weaker 6 mJy source in as little as 24 h. Adding cosmological constraints from the Atacama Cosmology Telescope (ACT) suppresses the predicted number of all the absorbers by as much as an order of magnitude. In the presence of a background of ambient Ly? photons of sufficient intensity to couple the gas spin temperature to the kinetic temperature, as may be produced by the first star-forming objects, the number of weak absorption systems is substantially boosted, by more than two orders of magnitude, rendering the signal readily detectable. Weak absorption features arising from the cold infalling regions around the minihaloes may appear as mock emission lines relative to the suppressed continuum level. A moderate amount of heating of the intergalactic medium (IGM), however, would greatly reduce the overall number of absorption systems. By contrast, the absorption signal of minihaloes against the CMB is distinguishable from the diffuse IGM signature only for a limited scenario of essentially no feedback and moderate redshifts, z < 19. The strength of the signal is dominated by the more massive minihaloes, and so is sensitive to a cut-off in the upper minihalo mass range imposed by any star formation and its consequences. Once the first star-forming systems provide feedback in the form of Ly? photons, the diffuse IGM signal will quickly dominate the signal from minihaloes because of the small total fraction of IGM mass in the minihalo cores.

Meiksin, Avery

2011-10-01

98

High redshift in greatness scale caused by Interstellar and Intergalactic Media  

NASA Astrophysics Data System (ADS)

According to QFT it is deduced that the gravitation is likely to originate from the polarization effect of Dirac vacuum fluctuation (Chen Shao-Guang, Nuovo Cimento B 104, 611, 1989) . In Dirac vacuum the lowest-energy virtual neutrinos u possess most number, which exert isotropic colliding pressure to isolated mass-point A (m ) , the net force on A is zero. For another masspoint B (M ) near A to obstruct u flux shooting to A, the u number along the line connecting A and B will decrease and destroy isotropic distribution of u, which leads to not only the change in momentum P (produces net u flux and net force Fp) but also the change in energy E or rest mass m (produces net force Fm). From the definition of force: F = Fp + Fm, Fp = m ( d v / d t ) , Fm = v (d m / d t ) (1) on A (or B) net force F Q (quasi-Casimir pressure of weak interaction) is: F Q = Fp + Fm = - K (m M /r 2 ) ( r/r ) + (v/c ) (2) According to the change in masses caused by Bondi's inductive transfer of energy in GR (H. Bondi, Proc. R. Soc. London A 427, 249, 1990) and Eq. (1) a new gravitational formula is deduced: F G = Fp + Fm = - G (m M /r 2 ) (r/r ) + (v/c ) (3) F G is equivalent to Einstein's equation, then we can solve the multi-bodies gravitational problems. K calculated from the weak-electromagnetism unified theory (W-EUT) has the same order of magnitude as experimental gravitational constant G. F G and F Q as a bridge joins QFT and GR. If K = G, gravitational theory would be merged into W-EUT. The gravitational laws predicted by F G and F Q are identical except that F Q has quantum effects but F G has not, F G has Lense- Thirring effect but FQ has not. Because Fp • d s= 0, the relative loss rate of total energy of A in a period T of circular motion around B calculated from Fm = - G (m M /r 2 ) (v/c ) is: lr = F m d s / m c 2 = - 4 (pi) 2 G M / c 3 T (4) Eq.(4) is a typical dipole radiation formula and approves directly Will's conjecture (C.M.Will, Phys. Rep. 113, 345,1984) . A gravitational wave of dipole radiation will be produced from the change in masses of A and B caused by the nonlinearity of Einstein's equation or by mass renormalization of QFT. The change in period of energy loss of pulsar binary PSR1913+16 calculated with Eq. (4) is consistent with the observation value of Taylar et al. The change in mass of photons on the way calculated from F Q or F G is the redshift ratio: Red=(E-Ei)/Ei= F G ds / Ei = - 4 GM / c 2 D (5) Where E is actual energy, Ei is in inertial system energy, which is just the metrical definition of redshift. The redshift ratio of Eq. (5) is numerically equal to the deflection ratio of GR, which is consistent with relativistic combination of energy and momentum. When light sweep the sun once maximal redshift ratio is 4GM / c2 R =-8×10-6 . When photons pass through greatness scale interstellar and intergalactic media high gravitational redshift will arises, e.g., if universal luminosity mass density ( about 10-31 g cm -3 )is entirely constituted by stars with M in homogeneous distribution, the distance of two stars is about 800 PC, maximal redshift constant is 3000 km s-1 / MPC, average value is 62.5 km s-1 / MPC ( near the observational Hubble's constant ), which will influence astronomical distance estimated by redshift and many astrophysical parameter.

Chen, Shao-Guang

99

TeV gamma rays from 3C 279 - A possible probe of origin and intergalactic infrared radiation fields  

NASA Technical Reports Server (NTRS)

The gamma-ray spectrum of 3C 279 during 1991 June exhibited a near-perfect power law between 50 MeV and over 5 GeV with a differential spectral index of -(2.02 +/- 0.07). If extrapolated, the gamma-ray spectrum of 3C 279 should be easily detectable with first-generation air Cerenkov detectors operating above about 0.3 TeV provided there is no intergalactic absorption. However, by using model-dependent lower and upper limits for the extragalactic infrared background radiation field, a sharp cutoff of the 3C 279 spectrum is predicted at between about 0.1 and about 1 TeV. The sensitivity of present air Cerenkov detectors is good enough to measure such a cutoff, which would provide the first opportunity to obtain a measurement of the extragalactic background infrared radiation field.

Stecker, F. W.; De Jager, O. C.; Salamon, M. H.

1992-01-01

100

THE CARBON CONTENT OF INTERGALACTIC GAS AT z = 4.25 AND ITS EVOLUTION TOWARD z = 2.4  

SciTech Connect

This paper presents ionization-corrected measurements of the carbon abundance in intergalactic gas at 4.0 < z < 4.5, using spectra of three bright quasars obtained with the Magellan Inamori Kycocera Echelle spectrograph on Magellan. By measuring the C IV strength in a sample of 131 discrete H I-selected quasar absorbers with {rho}/{rho}-bar {>=} 1.6, we derive a median carbon abundance of [C/H]=-3.55, with lognormal scatter of approximately {sigma} {approx} 0.8 dex. This median value is a factor of two to three lower than similar measurements made at z {approx} 2.4 using C IV and O VI. The strength of evolution is modestly dependent on the choice of UV background spectrum used to make ionization corrections, although our detection of an abundance evolution is generally robust with respect to this model uncertainty. We present a framework for analyzing the effects of spatial fluctuations in the UV ionizing background at frequencies relevant for C IV production. We also explore the effects of reduced flux between 3 and 4 Rydbergs (as from He II Lyman series absorption) on our abundance estimates. At He II line absorption levels similar to published estimates, the effects are very small, although a larger optical depth could reduce the strength of the abundance evolution. Our results imply that {approx}50% of the heavy elements seen in the intergalactic medium at z {approx} 2.4 were deposited in the 1.3 Gyr between z {approx} 4.3 and z {approx} 2.4. The total implied mass flux of carbon into the Ly{alpha} forest would constitute {approx}30% of the IMF-weighted carbon yield from known star-forming populations over this period.

Simcoe, Robert A. [MIT-Kavli Center for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-6640, Cambridge, MA 02139 (United States)

2011-09-10

101

The Properties of Low Redshift Intergalactic O VI Absorbers Determined from High S/N Observations of 14 QSOs with the Cosmic Origins Spectrograph  

NASA Astrophysics Data System (ADS)

We report on the observed properties of the plasma revealed through high signal-to-noise observations of 54 intervening O VI absorption systems containing 85 O VI and 133 H I components in a blind survey of 14 QSOs observed at ~18 km s-1 resolution with the Cosmic Origins Spectrograph over a redshift path of 3.52 at z < 0.5. Simple systems with one or two H I components and one O VI component comprise 50% of the systems. For a sample of 45 well-aligned absorption components where the temperature can be estimated, we find evidence for cool photoionized gas in 31 (69%) and warm gas (6 > log T > 5) in 14 (31%) of the components. The total hydrogen content of the 14 warm components can be estimated from the temperature and the measured value of log N(H I). The very large implied values of log N(H) range from 18.38 to 20.38 with a median of 19.35. The metallicity, [O/H], in the 6 warm components with log T > 5.45 ranges from -1.93 to 0.03 with a median value of -1.0 dex. Ground-based galaxy redshift studies reveal that most of the absorbers we detect sample gas in the intergalactic medium extending 200 to 600 kpc beyond the closest associated galaxy. For the warm aligned O VI absorbers, we estimate ?b(O VI)Warm = 0.0019 ± 0.0005 which corresponds to (4.1 ± 1.1)% of the baryons at low z. The warm plasma traced by the aligned O VI and H I absorption contains nearly as many baryons as are found in galaxies. Based on observations obtained with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-2655, and the NASA-CNES/ESA Far-Ultraviolet Spectroscopic Explorer mission operated by Johns Hopkins University, supported by NASA contract NAS 05-32885.

Savage, B. D.; Kim, T.-S.; Wakker, B. P.; Keeney, B.; Shull, J. M.; Stocke, J. T.; Green, J. C.

2014-05-01

102

INTERMITTENCE OF THE MAP OF THE KINETIC SUNYAEV-ZEL'DOVICH EFFECT AND TURBULENCE OF THE INTERGALACTIC MEDIUM  

SciTech Connect

We investigate the possibility of detecting the turbulent state of the intergalactic medium (IGM) with the kinetic Sunyaev-Zel'dovich (kSZ) effect. Being sensitive to the divergence-free component of the momentum field of the IGM, the kSZ effect might be used to probe the vorticity of the turbulent IGM. With cosmological hydrodynamical simulation in the concordance {Lambda}CDM universe, we find that the structure functions of two-dimensional kSZ maps show strong intermittence, and the intermittent exponents follow a law similar to the She-Leveque scaling formula of fully developed turbulence. We also find that the intermittence is weak in the maps of thermal Sunyaev-Zel'dovich (tSZ) effect. Nevertheless, the superposition of the kSZ and tSZ effects still contain significant intermittence. We conclude that the turbulent behavior of the IGM may be revealed by the observation of the SZ effect on angular scales equal to or less than 0.5 arcmin, corresponding to the multipole parameter l {>=} 2 x 10{sup 4}.

Zhu Weishan; Feng Longlong [Purple Mountain Observatory, Nanjing, 210008 (China); Fang Lizhi [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States)

2011-06-10

103

DISCOVERY OF A LARGE-SCALE GALAXY FILAMENT NEAR A CANDIDATE INTERGALACTIC X-RAY ABSORPTION SYSTEM  

SciTech Connect

We present an analysis of the large-scale galaxy distribution around two possible warm-hot intergalactic medium (WHIM) absorption systems reported along the Markarian 421 sight line. Using the Sloan Digital Sky Survey (SDSS), we find a prominent galaxy filament at the redshift of the z = 0.027 X-ray absorption line system. The filament exhibits a width of 3.2 Mpc and a length of at least 20 Mpc, comparable to the size of WHIM filaments seen in cosmological simulations. No individual galaxies fall within 350 projected kpc so it is unlikely that the absorption is associated with gas in a galaxy halo or outflow. Another, lower-significance X-ray absorption system was reported in the same Chandra spectrum at z = 0.011, but the large-scale structure in its vicinity is far weaker and may be a spurious alignment. By searching for similar galaxy structures in 140 random smoothed SDSS fields, we estimate an {approx}5%-10% probability of the z = 0.027 absorber-filament alignment occurring by chance. If these two systems are indeed physically associated, this would represent the first known coincidence between a large-scale galaxy structure and a blind X-ray WHIM detection.

Williams, Rik J.; Mulchaey, John S.; Kollmeier, Juna A.; Cox, Thomas J., E-mail: williams@obs.carnegiescience.ed [Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101 (United States)

2010-11-20

104

The thermal history of the intergalactic medium down to redshift z = 1.5: a new curvature measurement  

NASA Astrophysics Data System (ADS)

According to the photoheating model of the intergalactic medium (IGM), He II reionization is expected to affect its thermal evolution. Evidence for additional energy injection into the IGM has been found at 3 ? z ? 4, though the evidence for the subsequent fall-off below z ˜ 2.8 is weaker and depends on the slope of the temperature-density relation, ?. Here we present, for the first time, an extension of the IGM temperature measurements down to the atmospheric cut-off of the H I Lyman-? (Ly?) forest at z ? 1.5. Applying the curvature method on a sample of 60 Ultraviolet and Visual Echelle Spectrograph (UVES) spectra we investigated the thermal history of the IGM at z < 3 with precision comparable to the higher redshift results. We find that the temperature of the cosmic gas traced by the Ly? forest [T(bar{? })] increases for increasing overdensity from T(bar{? })˜ 22670 to 33740 K in the redshift range z ˜ 2.8-1.6. Under the assumption of two reasonable values for ?, the temperature at the mean density (T0) shows a tendency to flatten at z ? 2.8. In the case of ? ˜ 1.5, our results are consistent with previous ones which indicate a falling T0 for redshifts z ? 2.8. Finally, our T(bar{? }) values show reasonable agreement with moderate blazar heating models.

Boera, Elisa; Murphy, Michael T.; Becker, George D.; Bolton, James S.

2014-07-01

105

The distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe  

NASA Technical Reports Server (NTRS)

The evolution and distribution of galaxies and the intergalactic medium (IGM) have been studied, along with collisionless dark matter in a Universe dominated by cold dark matter. The Einstein-deSitter universe with omega sub 0 = 1 and h = 0.5 was considered (here h = H sub 0 bar 100/kms/Mpc and H sub 0 is the present value of the Hubble constant). It is assumed that initially dark matter composes 90 pct and baryonic matter composes 10 pct of total mass, and that the primordial baryonic matter is comprised of H and He, with the abundance of He equal to 10 pct of H by number. Galaxies are allowed to form out of the IGM, if the total density and baryonic density satisfy an overdensity criterion. Subsequently, the newly formed galaxies release 10 to the 60th ergs of energy into the IGM over a period of 10 to the 8th years. Calculations have been performed with 32 to the 3rd dark matter particles and 32 to the 3rd cells in a cube with comoving side length L = 9.6/h Mpc. Dark matter particles and galaxies have been followed with an N-body code, while the IGM has been followed with a fluid code.

Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

1988-01-01

106

Constraining Intergalactic Magnetic Field with Fermi-LAT Observation of Cascade Radiation for TeV Blazars  

NASA Astrophysics Data System (ADS)

The problem concerning the origin of the Intergalactic Magnetic Field (IGMF) is one of the long-standing problems of astrophysics and cosmology, and direct measurements are difficult. TeV photons emitted by TeV blazars produce electron-positron pairs because of interactions with the extragalactic background light (EBL). These pairs emit secondary cascade gamma-rays via Inverse Compton scattering of the cosmic microwave background (CMB) photons. In this process, the trajectories of the pairs are deviated by the IGMF, and the cascade gamma-ray emission appears as extended emission around TeV source. We used the EBL, synchrotron self-Compton (SSC) model and the observed limits on Lorentz factor of electron-positron pairs to calculate the cascade-radiation spectrum, and then to fit the observed GeV to TeV and multi-waveband spectra of TeV blazars to constrain the IGMF. We obtained the GeV energy spectra of three TeV blazars by analyzing the Fermi-LAT data of the past ˜ 3 yr. The flux upper limits of Fermi-LAT in the 90% significant level of 1ES 0229+200 suggests that the IGMF is stronger than 2 × 10-18 G for an engine time of TeV activity with three years. The relationships between the deduced lower limits of IGMF and various engine times for 1ES 0229+200 and 1ES 0347-121 are presented by us.

Yang, Jianping; Wang, Jiancheng; Yang, Jianrong

2012-10-01

107

The abundances of carbon, nitrogen and oxygen in galactic haloes and the intergalactic medium  

NASA Astrophysics Data System (ADS)

Early results from spacecraft UV observations of the chemical composition of interstellar gas in the solar neighborhood and in the gaseous halo of the Galaxy are reported, along with progress in observational and analytical techniques. The database was gathered mainly with the Copernicus and IUE spacecraft, and is expected to be greatly enhanced with the launch of the Space Telescope. A depletion of CNO has been noted in interstellar gas, and no model has presently accounted for the missing element fractions. The few abundance determinations that have been made for the galactic halo indicate that the chemical abundances in nearby clouds are similar to solar abundances, thereby supporting models that posit the galactic disk as the origin of the interstellar medium in the halo. Techniques are proposed for using QSO absorption and emission lines, particularly the Lyman alpha line, as a probe to heavier elements in clouds along the line of sight to the distant objects. The success of the method will rely heavily on successful characterization of QSO spectra.

Pettini, M.

108

THE NATURE OF THE WARM/HOT INTERGALACTIC MEDIUM. I. NUMERICAL METHODS, CONVERGENCE, AND O VI ABSORPTION  

SciTech Connect

We perform a series of cosmological simulations using Enzo, an Eulerian adaptive-mesh refinement, N-body + hydrodynamical code, applied to study the warm/hot intergalactic medium (WHIM). The WHIM may be an important component of the baryons missing observationally at low redshift. We investigate the dependence of the global star formation rate and mass fraction in various baryonic phases on spatial resolution and methods of incorporating stellar feedback. Although both resolution and feedback significantly affect the total mass in the WHIM, all of our simulations find that the WHIM fraction peaks at z {approx} 0.5, declining to 35%-40% at z = 0. We construct samples of synthetic O VI absorption lines from our highest-resolution simulations, using several models of oxygen ionization balance. Models that include both collisional ionization and photoionization provide excellent fits to the observed number density of absorbers per unit redshift over the full range of column densities (10{sup 13} cm{sup -2} {approx}< N{sub OVI} {approx}< 10{sup 15} cm{sup -2}). Models that include only collisional ionization provide better fits for high column density absorbers (N{sub OVI} {approx}> 10{sup 14} cm{sup -2}). The distribution of O VI in density and temperature exhibits two populations: one at T {approx} 10{sup 5.5} K (collisionally ionized, 55% of total O VI) and one at T {approx} 10{sup 4.5} K (photoionized, 37%) with the remainder located in dense gas near galaxies. While not a perfect tracer of hot gas, O VI provides an important tool for a WHIM baryon census.

Smith, Britton D.; Hallman, Eric J.; Shull, J. Michael [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); O'Shea, Brian W., E-mail: britton.smith@colorado.edu, E-mail: michael.shull@colorado.edu [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2011-04-10

109

Relativistic Pair Beams from TeV Blazars: A Source of Reprocessed GeV Emission rather than Intergalactic Heating  

NASA Astrophysics Data System (ADS)

The interaction of TeV photons from blazars with the extragalactic background light produces a relativistic beam of electron-positron pairs streaming through the intergalactic medium (IGM). The fate of the beam energy is uncertain. By means of two- and three-dimensional particle-in-cell simulations, we study the nonlinear evolution of dilute ultra-relativistic pair beams propagating through the IGM. We explore a wide range of beam Lorentz factors ? b Gt 1 and beam-to-plasma density ratios ? Lt 1, so that our results can be extrapolated to the extreme parameters of blazar-induced beams (? b ~ 106 and ? ~ 10-15, for powerful blazars). For cold beams, we show that the oblique instability governs the early stages of evolution, but its exponential growth terminates—due to self-heating of the beam in the transverse direction—when only a negligible fraction ~(?/? b )1/3 ~ 10-7 of the beam energy has been transferred to the IGM plasma. Further relaxation of the beam proceeds through quasi-longitudinal modes, until the momentum dispersion in the direction of propagation saturates at ?p b, ?/? b mec ~ 0.2. This corresponds to a fraction ~10% of the beam energy—irrespective of ? b or ?—being ultimately transferred to the IGM plasma (as compared to the heating efficiency of ~50% predicted by one-dimensional models, which cannot properly account for the transverse broadening of the beam). For the warm beams generated by TeV blazars, the development of the longitudinal relaxation is suppressed, since the initial dispersion in beam momentum is already ?p b0, ?/? b mec >~ 1. Here, the fraction of beam energy ultimately deposited into the IGM is only ~? ? b ~ 10-9. It follows that most of the beam energy is still available to power the GeV emission produced by inverse Compton up-scattering of the cosmic microwave background by the beam pairs.

Sironi, Lorenzo; Giannios, Dimitrios

2014-05-01

110

Detection of an intergalactic meteor particle with the 6-m telescope  

NASA Astrophysics Data System (ADS)

On July 28, 2006 the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences recorded the spectrum of a faint meteor. We confidently identify the lines of FeI and MgI, OI, NI and molecular-nitrogen (N2) bands. The entry velocity of the meteor body into the Earth’s atmosphere estimated from radial velocity is equal to 300 km/s. The body was several tens of a millimeter in size, like chondrules in carbon chondrites. The radiant of the meteor trajectory coincides with the sky position of the apex of the motion of the Solar system toward the centroid of the Local Group of galaxies. Observations of faint sporadic meteors with FAVOR TV CCD camera confirmed the radiant at a higher than 96% confidence level. We conclude that this meteor particle is likely to be of extragalactic origin. The following important questions remain open: (1) How metal-rich dust particles came to be in the extragalactic space? (2) Why are the sizes of extragalactic particles larger by two orders of magnitude (and their masses greater by six orders of magnitude) than common interstellar dust grains in our Galaxy? (3) If extragalactic dust surrounds galaxies in the form of dust (or gas-and-dust) aureoles, can such formations now be observed using other observational techniques (IR observations aboard Spitzer satellite, etc.)? (4) If inhomogeneous extragalactic dust medium with the parameters mentioned above actually exists, does it show up in the form of irregularities on the cosmic microwave background (WMAP etc.)?

Afanasiev, V. L.; Kalenichenko, V. V.; Karachentsev, I. D.

2007-12-01

111

The Last Eight-Billion Years of Intergalactic C IV Evolution  

NASA Astrophysics Data System (ADS)

We surveyed the Hubble Space Telescope UV spectra of 49 low-redshift quasars for z < 1 C IV candidates, relying solely on the characteristic wavelength separation of the doublet. After consideration of the defining traits of C IV doublets (e.g., consistent line profiles, other associated transitions, etc.), we defined a sample of 38 definite (group G = 1) and five likely (G = 2) doublets with rest equivalent widths Wr for both lines detected at ? 3?_{W_{r}}. We conducted Monte Carlo completeness tests to measure the unblocked redshift (?z) and co-moving path length (?X) over which we were sensitive to C IV doublets of a range of equivalent widths and column densities. The absorber line density of (G = 1+2) doublets is {d}{N}_{{C IV}}/{d}X= 4.1^{+0.7}_{-0.6} for log N(C+3) >= 13.2, and {d}{N}_{{C IV}}/{d}X has not evolved significantly since z = 5. The best-fit power law to the G = 1 frequency distribution of column densities f(N({C}^{+3})) ? k(N({C}^{+3})/N_{0})^{?_{N}} has coefficient k = 0.67+0.18 -0.16 × 10-14 cm2 and exponent ? N = -1.50+0.17 -0.19, where N 0 = 1014 cm-2. Using the power-law model of f(N(C+3)), we measured the C+3 mass density relative to the critical density: ? _{{C}^{+3}}= (6.20^{+1.82}_{-1.52}) × 10^{-8} for 13 <= log N(C+3) <= 15. This value is a 2.8 ± 0.7 increase in ? _{{C}^{+3}} compared to the error-weighted mean from several 1 < z < 5 surveys for C IV absorbers. A simple linear regression to ?_{{C}^{+3}} over the age of the universe indicates that ?_{{C}^{+3}} has slowly but steadily increased from z = 5 ? 0, with {d}?_{{C}^{+3}}/ {d}t_age = (0.42± 0.2)× 10^{-8} Gyr^{-1}.

Cooksey, Kathy L.; Thom, Christopher; Prochaska, J. Xavier; Chen, Hsiao-Wen

2010-01-01

112

A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-Ray Opacity of the Universe  

NASA Technical Reports Server (NTRS)

We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of red shift using an approach based on observational data obtained at in different wavelength bands from local to deep galaxy surveys. Our empirically based approach allows us, for the firs.t time, to obtain a completely model independent determination of the IBL and to quantify its uncertainties. Using our results on the IBL, we then place upper and lower limits on the opacity of the universe to gamma-rays, independent of previous constraints.

Stecker, Floyd W.

2012-01-01

113

The Cosmological Impact of Luminous TeV Blazars. II. Rewriting the Thermal History of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The universe is opaque to extragalactic very high energy gamma rays (VHEGRs, E > 100 GeV) because they annihilate and pair produce on the extragalactic background light. The resulting ultrarelativistic pairs are commonly assumed to lose energy primarily through inverse Compton scattering of cosmic microwave background (CMB) photons, reprocessing the original emission from TeV to GeV energies. In Broderick et al., we argued that this is not the case; powerful plasma instabilities driven by the highly anisotropic nature of the ultrarelativistic pair distribution provide a plausible way to dissipate the kinetic energy of the TeV-generated pairs locally, heating the intergalactic medium (IGM). Here, we explore the effect of this heating on the thermal history of the IGM. We collate the observed extragalactic VHEGR sources to determine a local VHEGR heating rate. Given the pointed nature of VHEGR observations, we estimate the correction for the various selection effects using Fermi observations of high- and intermediate-peaked BL Lac objects. As the extragalactic component of the local VHEGR flux is dominated by TeV blazars, we then estimate the evolution of the TeV blazar luminosity density by tying it to the well-observed quasar luminosity density and producing a VHEGR heating rate as a function of redshift. This heating is relatively homogeneous for z <~ 4, but there is greater spatial variation at higher redshift (order unity at z ~ 6) because of the reduced number of blazars that contribute to local heating. We show that this new heating process dominates photoheating in the low-redshift evolution of the IGM and calculate the effect of this heating in a one-zone model. As a consequence, the inclusion of TeV blazar heating qualitatively and quantitatively changes the structure and history of the IGM. Due to the homogeneous nature of the extragalactic background light, TeV blazars produce a uniform volumetric heating rate. This heating is sufficient to increase the temperature of the mean density IGM by nearly an order of magnitude, and at low densities by substantially more. It also naturally produces the inverted temperature-density relation inferred by recent observations of the high-redshift Ly? forest, a feature that is difficult to reconcile with standard reionization models. Finally, we close with a discussion on the possibility of detecting this hot low-density IGM suggested by our model either directly or indirectly via the local Ly? forest, the Comptonized CMB, or free-free emission, but we find that such measurements are currently not feasible.

Chang, Philip; Broderick, Avery E.; Pfrommer, Christoph

2012-06-01

114

The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6  

NASA Astrophysics Data System (ADS)

We investigate the effect of primordial helium on hydrogen reionization using a hydrodynamical simulation combined with the cosmological radiative transfer code CRASH. The radiative transfer simulations are performed in a 35.12 h-1 comoving Mpc box using a variety of assumptions for the amplitude and power-law extreme-ultraviolet (EUV) spectral index of the ionizing emissivity at z > 6. We use an empirically motivated prescription for ionizing sources which, by design, ensures all of the models are consistent with constraints on the Thomson scattering optical depth and the metagalactic hydrogen photoionization rate at z˜ 6. The inclusion of helium slightly delays reionization due to the small number of ionizing photons which reionize neutral helium instead of hydrogen. However, helium has a significant impact on the thermal state of the intergalactic medium (IGM) during hydrogen reionization. Models with a soft EUV spectral index, ?= 3, produce IGM temperatures at the mean density at z˜ 6, T0? 10 500 K, which are ˜20 per cent higher compared to models in which helium photoheating is excluded. Harder EUV indices produce even larger IGM temperature boosts by the end of hydrogen reionization. A comparison of these simulations to recent observational estimates of the IGM temperature at z˜ 5-6 suggests that hydrogen reionization was primarily driven by Population II stellar sources with a soft EUV index, ?. We also find that faint, as yet undetected galaxies, characterized by a luminosity function with a steepening faint-end slope (?LF?-2) and an increasing Lyman continuum escape fraction (fesc˜ 0.5), are required to reproduce the ionizing emissivity used in our simulations at z > 6. Finally, we note there is some tension between recent observational constraints which indicate the IGM is >10 per cent neutral by volume z˜ 7, and estimates of the ionizing emissivity at z= 6 which indicate only 1-3 ionizing photons are emitted per hydrogen atom over a Hubble time at z= 6. This tension may be alleviated by either a lower neutral fraction at z˜ 7 or an IGM which still remains a few per cent neutral by volume at z= 6.

Ciardi, B.; Bolton, J. S.; Maselli, A.; Graziani, L.

2012-06-01

115

The intergalactic medium over the last 10 billion years - II. Metal-line absorption and physical conditions  

NASA Astrophysics Data System (ADS)

We investigate the metallicity evolution and metal content of the intergalactic medium (IGM) and galactic halo gas from z= 2 to 0 using 110-million-particle cosmological hydrodynamic simulations. We focus on the detectability and physical properties of ultraviolet resonance metal-line absorbers observable with Hubble's Cosmic Origins Spectrograph (COS). We confirm that galactic superwind outflows are required to enrich the IGM to observed levels down to z= 0 using three wind prescriptions contrasted to a no-wind simulation. Our favoured momentum-conserved wind prescription deposits metals closer to galaxies owing to its moderate energy input, while the more energetic constant wind model enriches the warm-hot IGM 6.4 times more. Despite these significant differences, all wind models produce metal-line statistics within a factor of 2 of existing observations. This is because ?, ?, ? and ? absorbers primarily arise from T < 105 K, photoionized gas that is enriched to similar levels in the three feedback schemes. ? absorbers trace the diffuse phase with ?, which is enriched to ˜1/50 Z? at z= 0, although the absorbers themselves usually exceed 0.3 Z? and arise from inhomogeneously distributed, unmixed winds. Turbulent broadening is required to match the observed equivalent width and column density statistics for ?. ? and ? absorbers trace primarily T˜ 104 K gas inside haloes (?), although there appear to be too many ? absorbers relative to observations. We predict the COS will observe a population of ? photoionized absorbers tracing T < 105 K, ? gas with equivalent widths of 10-20 mÅ. ? and ? are rarely detected in COS signal-to-noise ratio 30 simulated sight-lines (dn/dz? 1), although simulated ? detections trace halo gas at T= 106-107 K. In general, the IGM is enriched in an outside-in manner, where wind-blown metals released at higher redshift reach lower overdensities, resulting in higher ionization species tracing lower density, older metals. At z= 0, 90 per cent of baryons outside galaxies are enriched to ?, but 65 per cent of unbound baryons in the IGM have ? and contain only 4 per cent of all metals, a large decline from 20 per cent at z= 2, because metals from early winds often re-accrete on to galaxies while later winds are less likely to escape their haloes. We emphasize that our results are sensitive to how metal mixing is treated in the simulations, and argue that the lack of mixing in our scheme may be the largest difference from other similar publications.

Oppenheimer, Benjamin D.; Davé, Romeel; Katz, Neal; Kollmeier, Juna A.; Weinberg, David H.

2012-02-01

116

A meeting with the universe: Science discoveries from the space program  

NASA Technical Reports Server (NTRS)

A general history of space exploration is presented. The solar system is discussed. The Sun-Earth relationship is considered, including magnetic fields, solar wind, the magnetosphere, and the Sun-weather relationship. The universe beyond the solar system is discussed. Topics include stellar and galactic evolution, quasars and intergalactic space. The effects of weightlessness and ionizing radiation on human beings are considered. The possibility of extraterrestrial life is discussed. Lunar and planetary exploration, solar-terrestrial physics, astrophysics, biomedical research and exobiology are reviewed. Numerons color illustrations are included.

French, B. M. (editor); Maran, S. P. (editor)

1981-01-01

117

COINCIDENCES BETWEEN O VI AND O VII LINES: INSIGHTS FROM HIGH-RESOLUTION SIMULATIONS OF THE WARM-HOT INTERGALACTIC MEDIUM  

SciTech Connect

With high-resolution (0.46 h{sup -1} kpc), large-scale, adaptive mesh-refinement Eulerian cosmological hydrodynamic simulations we compute properties of O VI and O VII absorbers from the warm-hot intergalactic medium (WHIM) at z = 0. Our new simulations are in broad agreement with previous simulations with {approx}40% of the intergalactic medium being in the WHIM. Our simulations are in agreement with observed properties of O VI absorbers with respect to the line incidence rate and Doppler-width-column-density relation. It is found that the amount of gas in the WHIM below and above 10{sup 6} K is roughly equal. Strong O VI absorbers are found to be predominantly collisionally ionized. It is found that (61%, 57%, 39%) of O VI absorbers of log N(O VI) cm{sup 2} = (12.5-13, 13-14, > 14) have T < 10{sup 5} K. Cross correlations between galaxies and strong [N(O VI) > 10{sup 14} cm{sup -2}] O VI absorbers on {approx}100-300 kpc scales are suggested as a potential differentiator between collisional ionization and photoionization models. Quantitative prediction is made for the presence of broad and shallow O VI lines that are largely missed by current observations but will be detectable by Cosmic Origins Spectrograph observations. The reported 3{sigma} upper limit on the mean column density of coincidental O VII lines at the location of detected O VI lines by Yao et al. is above our predicted value by a factor of 2.5-4. The claimed observational detection of O VII lines by Nicastro et al., if true, is 2{sigma} above what our simulations predict.

Cen Renyue, E-mail: cen@astro.princeton.edu [Princeton University Observatory, Princeton, NJ 08544 (United States)

2012-07-01

118

LOWER BOUNDS ON MAGNETIC FIELDS IN INTERGALACTIC VOIDS FROM LONG-TERM GeV-TeV LIGHT CURVES OF THE BLAZAR MRK 421  

SciTech Connect

Lower bounds are derived on the amplitude B of intergalactic magnetic fields (IGMFs) in the region between Galaxy and the blazar Mrk 421, from constraints on the delayed GeV pair-echo flux that are emitted by secondary e {sup -} e {sup +} produced in {gamma}{gamma} interactions between primary TeV gamma rays and the cosmic infrared background. The distribution of galaxies mapped by the Sloan Digital Sky Survey shows that this region is dominated by a large intergalactic void. We utilize data from long-term, simultaneous GeV-TeV observations by the Fermi Large Area Telescope and the ARGO-YBJ experiment extending over 850 days. For an assumed value of B, we evaluate the daily GeV pair-echo flux expected from the TeV data, select the dates where this exceeds the Fermi 2{sigma} sensitivity, compute the probability that this flux is excluded by the Fermi data for each date, and then combine the probabilities using the inverse normal method. Consequently, we exclude B < 10{sup -20.5} G for a field coherence length of 1 kpc at {approx}4{sigma} level, as long as plasma instabilities are unimportant for cooling of the pair beam. This is much more significant than the 2{sigma} bounds we obtained previously from observations of Mrk 501, by virtue of more extensive data from the ARGO-YBJ, as well as improved statistical analysis. Compared with most other studies of IGMF bounds, the evidence we present here for a non-zero IGMF is more robust as it does not rely on unproven assumptions on the primary TeV emission during unobserved periods.

Takahashi, Keitaro [Department of Physics, Kumamoto University, 2-39-1, Kurokami, Kumamoto 860-8555 (Japan); Mori, Masaki [Department of Physical Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan); Ichiki, Kiyotomo [Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Inoue, Susumu [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Takami, Hajime, E-mail: keitaro@sci.kumamoto-u.ac.jp [Theory Center, Institute of Particle and Nuclear Studies, KEK, 1-1, Oho, Tsukuba 305-0801 (Japan)

2013-07-10

119

THE SIZE AND ORIGIN OF METAL-ENRICHED REGIONS IN THE INTERGALACTIC MEDIUM FROM SPECTRA OF BINARY QUASARS  

SciTech Connect

We present tomography of the circum-galactic metal distribution at redshift 1.7-4.5 derived from echellete spectroscopy of binary quasars. We find C IV systems at similar redshifts in paired sightlines more often than expected for sightline-independent redshifts. As the separation of the sightlines increases from 36 kpc to 907 kpc, the amplitude of this clustering decreases. At the largest separations, the C IV systems cluster similar to the Lyman-break galaxies studied by Adelberger et al. in 2005. The C IV systems are significantly less correlated than these galaxies, however, at separations less than R{sub 1} {approx_equal} 0.42 {+-} 0.15 h {sup -1} comoving Mpc. Measured in real space, i.e., transverse to the sightlines, this length scale is significantly smaller than the break scale estimated previously from the line-of-sight correlation function in redshift space by Scannapieco et al. in 2006. Using a simple model, we interpret the new real-space measurement as an indication of the typical physical size of enriched regions. We adopt this size for enriched regions and fit the redshift-space distortion in the line-of-sight correlation function. The fitted velocity kick is consistent with the peculiar velocity of galaxies as determined by the underlying mass distribution and places an upper limit on the average outflow (or inflow) speed of metals. The implied timescale for dispersing metals is larger than the typical stellar ages of Lyman-break galaxies, and we argue that enrichment by galaxies at z {>=} 4.3 played a greater role in dispersing metals. To further constrain the growth of enriched regions, we discuss empirical constraints on the evolution of the C IV correlation function with cosmic time. This study demonstrates the potential of tomography for measuring the metal enrichment history of the circum-galactic medium.

Martin, Crystal L.; Fournier, Amanda P. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, V8P 1A1 (Canada); Hennawi, Joseph F. [Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720-3411 (United States); Djorgovski, S. G., E-mail: cmartin@physics.ucsb.ed [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

2010-09-20

120

The Contribution of the Kinematic Sunyaev-Zel'dovich Effect from the Warm-Hot Intergalactic Medium to the Five-Year Wilkinson Microwave Anisotropy Probe Data  

NASA Astrophysics Data System (ADS)

We study the contribution of the kinematic Sunyaev-Zel'dovich (kSZ) effect, generated by the warm-hot intergalactic medium, to the cosmic microwave background temperature anisotropies in the five-year Wilkinson Microwave Anisotropy Probe (WMAP) data. We explore the concordance ?CDM cosmological model, with and without this kSZ contribution, using a Markov chain Monte Carlo algorithm. Our model requires a single extra parameter to describe this new component. Our results show that the inclusion of the kSZ signal improves the fit to the data without significantly altering the best-fit cosmological parameters except ?b h 2. The improvement is localized at the ell gsim 500 multipoles. For the best-fit model, this extra component peaks at ell ~ 450 with an amplitude of 129 ?K2, and represents 3.1% of the total power measured by WMAP. Nevertheless, at the 2? level a null kSZ contribution is still compatible with the data. Part of the detected signal could arise from unmasked point sources and/or Poissonianly distributed foreground residuals. A statistically more significant detection requires the wider frequency coverage and angular resolution of the forthcoming Planck mission.

Génova-Santos, R.; Atrio-Barandela, F.; Mücket, J. P.; Klar, J. S.

2009-07-01

121

The intergalactic medium thermal history at redshift z = 1.7-3.2 from the Ly? forest: a comparison of measurements using wavelets and the flux distribution  

NASA Astrophysics Data System (ADS)

We investigate the thermal history of the intergalactic medium (IGM) in the redshift interval z = 1.7-3.2 by studying the small-scale fluctuations in the Lyman ? forest transmitted flux. We apply a wavelet filtering technique to 18 high-resolution quasar spectra obtained with the Ultraviolet and Visual Echelle Spectrograph, and compare these data to synthetic spectra drawn from a suite of hydrodynamical simulations in which the IGM thermal state and cosmological parameters are varied. From the wavelet analysis we obtain estimates of the IGM thermal state that are in good agreement with other recent, independent wavelet-based measurements. We also perform a reanalysis of the same data set using the Lyman ? forest flux probability distribution function (PDF), which has previously been used to measure the IGM temperature-density relation. This provides an important consistency test for measurements of the IGM thermal state, as it enables a direct comparison of the constraints obtained using these two different methodologies. We find the constraints obtained from wavelets and the flux PDF are formally consistent with each other, although in agreement with previous studies, the flux PDF constraints favour an isothermal or inverted IGM temperature-density relation. We also perform a joint analysis by combining our wavelet and flux PDF measurements, constraining the IGM thermal state at z = 2.1 to have a temperature at mean density of T0/[103 K] = 17.3 ± 1.9 and a power-law temperature-density relation exponent ? = 1.1 ± 0.1 (1?). Our results are consistent with previous observations that indicate there may be additional sources of heating in the IGM at z < 4.

Garzilli, A.; Bolton, J. S.; Kim, T.-S.; Leach, S.; Viel, M.

2012-08-01

122

New Limits on 21 cm Epoch of Reionization from PAPER-32 Consistent with an X-Ray Heated Intergalactic Medium at z = 7.7  

NASA Astrophysics Data System (ADS)

We present new constraints on the 21 cm Epoch of Reionization (EoR) power spectrum derived from three months of observing with a 32 antenna, dual-polarization deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. In this paper, we demonstrate the efficacy of the delay-spectrum approach to avoiding foregrounds, achieving over eight orders of magnitude of foreground suppression (in mK2). Combining this approach with a procedure for removing off-diagonal covariances arising from instrumental systematics, we achieve a best 2? upper limit of (41 mK)2 for k = 0.27 h Mpc-1 at z = 7.7. This limit falls within an order of magnitude of the brighter predictions of the expected 21 cm EoR signal level. Using the upper limits set by these measurements, we generate new constraints on the brightness temperature of 21 cm emission in neutral regions for various reionization models. We show that for several ionization scenarios, our measurements are inconsistent with cold reionization. That is, heating of the neutral intergalactic medium (IGM) is necessary to remain consistent with the constraints we report. Hence, we have suggestive evidence that by z = 7.7, the H I has been warmed from its cold primordial state, probably by X-rays from high-mass X-ray binaries or miniquasars. The strength of this evidence depends on the ionization state of the IGM, which we are not yet able to constrain. This result is consistent with standard predictions for how reionization might have proceeded.

Parsons, Aaron R.; Liu, Adrian; Aguirre, James E.; Ali, Zaki S.; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Dexter, Matthew R.; Gugliucci, Nicole E.; Jacobs, Daniel C.; Klima, Pat; MacMahon, David H. E.; Manley, Jason R.; Moore, David F.; Pober, Jonathan C.; Stefan, Irina I.; Walbrugh, William P.

2014-06-01

123

Probing intergalactic neutral hydrogen by the Lyman alpha red damping wing of gamma-ray burst 130606A afterglow spectrum at z = 5.913  

NASA Astrophysics Data System (ADS)

The unprecedentedly bright optical afterglow of GRB 130606A located by Swift at a redshift close to the reionization era (z = 5.913) provides a new opportunity to probe the ionization status of the intergalactic medium (IGM). Here we present an analysis of the red Ly? damping wing of the afterglow spectrum taken by Subaru/FOCAS during 10.4-13.2 hr after the burst. We find that the minimal model including only the baseline power-law and H I absorption in the host galaxy does not give a good fit, leaving residuals showing concave curvature in 8400-8900 Å with an amplitude of about 0.6% of the flux. Such a curvature in the short wavelength range cannot be explained either by extinction at the host with standard extinction curves, intrinsic curvature of afterglow spectra, or by the known systematic uncertainties in the observed spectrum. The red damping wing by intervening H I gas outside the host can reduce the residual by about 3 ? statistical significance. We find that a damped Ly? system is not favored as the origin of this intervening H I absorption, from the observed Ly? and metal absorption features. Therefore absorption by diffuse IGM remains as a plausible explanation. A fit by a simple uniform IGM model requires an H I neutral fraction of fH I ˜ 0.1-0.5 depending on the distance to the GRB host, implying high fH I IGM associated with the observed dark Gunn-Peterson (GP) troughs. This gives new evidence that the reionization is not yet complete at z = 6.

Totani, Tomonori; Aoki, Kentaro; Hattori, Takashi; Kosugi, George; Niino, Yuu; Hashimoto, Tetsuya; Kawai, Nobuyuki; Ohta, Kouji; Sakamoto, Takanori; Yamada, Toru

2014-06-01

124

Star Formation and the Interstellar Medium in Nearby Tidal Streams (SAINTS): Spitzer Mid-infrared spectroscopy and Imaging of Intergalactic Star-forming Objects  

NASA Astrophysics Data System (ADS)

A spectroscopic analysis of 10 intergalactic star-forming objects (ISFOs) and a photometric analysis of 67 ISFOs in a sample of 14 interacting systems is presented. The majority of the ISFOs have relative polycyclic aromatic hydrocarbon (PAH) band strengths similar to those of nearby spiral and starburst galaxies. In contrast to what is observed in blue compact dwarfs (BCDs) and local giant H II regions in the Milky Way (NGC 3603) and the Magellanic Clouds (30 Doradus and N 66), the relative PAH band strengths in ISFOs correspond to models with a significant PAH ion fraction (<50%) and bright emission from large PAHs (~100 carbon atoms). The [Ne III]/[Ne II] and [S IV]/[S III] line flux ratios indicate moderate levels of excitation with an interstellar radiation field that is harder than the majority of the Spitzer Infrared Nearby Galaxies Survey and starburst galaxies, but softer than BCDs and local giant H II regions. The ISFO neon line flux ratios are consistent with a burst of star formation lsim6 million years ago. Most of the ISFOs have ~106 M ? of warm H2 with a likely origin in photo-dissociation regions (PDRs). Infrared Array Camera photometry shows the ISFOs to be bright at 8 ?m, with one-third having [4.5] - [8.0] > 3.7, i.e., enhanced non-stellar emission, most likely due to PAHs, relative to normal spirals, dwarf irregulars, and BCD galaxies. The relative strength of the 8 ?m emission compared to that at 3.6 ?m or 24 ?m separates ISFOs from dwarf galaxies in Spitzer two-color diagrams. The infrared power in two-thirds of the ISFOs is dominated by emission from grains in a diffuse interstellar medium. One in six ISFOs have significant emission from PDRs, contributing ~30%-60% of the total power. ISFOs are young knots of intense star formation.

Higdon, S. J. U.; Higdon, J. L.; Smith, B. J.; Hancock, M.

2014-06-01

125

The Hubble Space Telescope: UV, Visible, and Near-Infrared Pursuits  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope continues to push the limits on world-class astrophysics. Cameras including the Advanced Camera for Surveys and the new panchromatic Wide Field Camera 3 which was installed nu last year's successful servicing mission S2N4,o{fer imaging from near-infrared through ultraviolet wavelengths. Spectroscopic studies of sources from black holes to exoplanet atmospheres are making great advances through the versatile use of STIS, the Space Telescope Imaging Spectrograph. The new Cosmic Origins Spectrograph, also installed last year, is the most sensitive UV spectrograph to fly io space and is uniquely suited to address particular scientific questions on galaxy halos, the intergalactic medium, and the cosmic web. With these outstanding capabilities on HST come complex needs for laboratory astrophysics support including atomic and line identification data. I will provide an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics.

Wiseman, Jennifer

2010-01-01

126

Servicing Mission 4 and the Extraordinary Science of the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

Just two years ago, NASA astronauts performed a challenging and flawless final Space Shuttle servicing mission to the orbiting Hubble Space Telescope. With science instruments repaired on board and two new ones installed, the observatory. is more powerful now than ever before. I will show the dramatic highlights of the servicing mission and present some of the early scientific results from the refurbished telescope. Its high sensitivity and multi-wavelength capabilities are revealing the highest redshift galaxies ever seen, as well as details of the cosmic web of intergalactic medium, large scale structure formation, solar system bodies, and stellar evolution. Enlightening studies of dark matter, dark energy, and exoplanet atmospheres add to the profound contributions to astrophysics that are being made with Hubble, setting a critical stage for future observatories such as the James Webb Space Telescope.

Wiseman, Jennifer J.

2012-01-01

127

Space Shuttle.  

National Technical Information Service (NTIS)

The space shuttle is discussed as a reusable space vehicle operated as a transportation system for space missions in low earth orbit. Space shuttle studies and operational capabilities are reported for potential missions indicating that about 38 percent a...

1974-01-01

128

Space Elevator: Path to Space  

NASA Astrophysics Data System (ADS)

The Space Elevator is the most promising Space Transportation system on the drawing boards today, combining scalability, qualify of ride, and safety to deliver truly commercial-grade space access-practically comparable to a train ride to space.

Kaushal, A. K.

2012-05-01

129

Intergalactic Medium Emission Observations with the Cosmic Web Imager. II. Discovery of Extended, Kinematically Linked Emission around SSA22 Ly? Blob 2  

NASA Astrophysics Data System (ADS)

The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Ly? blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Ly? emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Ly? emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 1011 M ?, and the dark halo mass is at least 2 × 1012 M ?. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding gas have significant and coaligned angular momentum, strengthening the case for their association.

Martin, D. Christopher; Chang, Daphne; Matuszewski, Matt; Morrissey, Patrick; Rahman, Shahin; Moore, Anna; Steidel, Charles C.; Matsuda, Yuichi

2014-05-01

130

Space Tug  

NASA Technical Reports Server (NTRS)

This Space Tug concept, proposed as a reusable multipurpose space vehicle to transport payloads to different orbital inclinations, was intended to serve as an important link between the Space Shuttle and the Space Station or any other orbital element requiring crew and/or cargo transportation. The Marshall Space Flight Center managed NASA's Space Tug activities. The Space Tug program was cancelled and did not become a reality.

2004-01-01

131

Space Travel  

NSDL National Science Digital Library

Students are introduced to the historical motivation for space exploration. They learn about the International Space Station as an example of space travel innovation and are introduced to new and futuristic ideas that space engineers are currently working on to propel space research far into the future!

Integrated Teaching And Learning Program

132

A LYMAN BREAK GALAXY IN THE EPOCH OF REIONIZATION FROM HUBBLE SPACE TELESCOPE GRISM SPECTROSCOPY  

SciTech Connect

We present observations of a luminous galaxy at z = 6.573-the end of the reionization epoch-which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which show a dramatic continuum break in the spectrum at rest frame 1216 A. The second confirmation is done with Keck + DEIMOS. The continuum is not clearly detected with ground-based spectra, but high wavelength resolution enables the Ly{alpha} emission line profile to be determined. We compare the line profile to composite line profiles at z = 4.5. The Ly{alpha} line profile shows no signature of a damping wing attenuation, confirming that the intergalactic gas is ionized at z = 6.57. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms, even at redshifts where Ly{alpha} is too attenuated by the neutral intergalactic medium to be detectable using traditional spectroscopy from the ground.

Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Zheng Zhenya [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ (United States); Pirzkal, Norbert; Grogin, Norman; Koekemoer, Anton; Peth, Michael A. [Space Telescope Science Institute, Baltimore, MD (United States); Spinrad, Hyron [University of California, Berkeley, CA (United States); Reddy, Naveen [University of California, Riverside, CA (United States); Hathi, Nimish [Observatories of the Carnegie Institution of Washington, Pasadena, CA (United States); Budavari, Tamas [Johns Hopkins University, Baltimore, MD (United States); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Gardner, Jonathan P. [NASA Goddard Space Flight Center, Astrophysics Science Division, Observational Cosmology Laboratory, Code 665, Greenbelt, MD 20771 (United States); Gronwall, Caryl [Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States); Haiman, Zoltan [Columbia University, New York, NY (United States); Kuemmel, Martin [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany); Meurer, Gerhardt, E-mail: James.Rhoads@asu.edu [International Centre for Radio Astronomy Research, University of Western Australia, M468, 35 Stirling Highway, Crawley, WA 6009 (Australia); and others

2013-08-10

133

A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope Grism Spectroscopy  

NASA Astrophysics Data System (ADS)

We present observations of a luminous galaxy at z = 6.573—the end of the reionization epoch—which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which show a dramatic continuum break in the spectrum at rest frame 1216 Å. The second confirmation is done with Keck + DEIMOS. The continuum is not clearly detected with ground-based spectra, but high wavelength resolution enables the Ly? emission line profile to be determined. We compare the line profile to composite line profiles at z = 4.5. The Ly? line profile shows no signature of a damping wing attenuation, confirming that the intergalactic gas is ionized at z = 6.57. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms, even at redshifts where Ly? is too attenuated by the neutral intergalactic medium to be detectable using traditional spectroscopy from the ground.

Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Hathi, Nimish; Grogin, Norman; Koekemoer, Anton; Peth, Michael A.; Cohen, Seth; Zheng, Zhenya; Budavari, Tamas; Ferreras, Ignacio; Gardner, Jonathan P.; Gronwall, Caryl; Haiman, Zoltan; Kümmel, Martin; Meurer, Gerhardt; Moustakas, Leonidas; Panagia, Nino; Pasquali, Anna; Sahu, Kailash; di Serego Alighieri, Sperello; Somerville, Rachel; Straughn, Amber; Walsh, Jeremy; Windhorst, Rogier; Xu, Chun; Yan, Haojing

2013-08-01

134

Birecurrent spaces.  

National Technical Information Service (NTIS)

A birecurrent space is defined with its classification and studied with involvement of Einstein, conformally flat, conformally symmetric and conformally recurrent spaces. A necessary and sufficient condition that a birecurrent space be recurrent is found....

M. S. Rahman

1991-01-01

135

Space Supplement.  

NASA Astrophysics Data System (ADS)

Clearing the space shuttle for launch (S. Young). Europe's four-man space capsule (T. Furniss). Uncertain return to a red planet (N. Booth). America's unlikely partners in space (D. Whitehouse). View from the Moon (B. Rose).

1994-07-01

136

Space station  

NASA Technical Reports Server (NTRS)

The history of American space flight indicates that a space station is the next logical step in the scientific pursuit of greater knowledge of the universe. The Space Station and its complement of space vehicles, developed by NASA, will add new dimensions to an already extensive space program in the United States. The Space Station offers extraordinary benefits for a comparatively modest investment (currently estimated at one-ninth the cost of the Apollo Program). The station will provide a permanent multipurpose facility in orbit necessary for the expansion of space science and technology. It will enable significant advancements in life sciences research, satellite communications, astronomy, and materials processing. Eventually, the station will function in support of the commercialization and industrialization of space. Also, as a prerequisite to manned interplanetary exploration, the long-duration space flights typical of Space Station missions will provide the essential life sciences research to allow progressively longer human staytime in space.

Stewart, Donald F.; Hayes, Judith

1989-01-01

137

Space colonization.  

PubMed

NASA interest in colonization encompasses space tourism; space exploration; space bases in orbit, at L1, on the Moon, or on Mars; in-situ resource utilization; and planetary terraforming. Activities progressed during 2002 in areas such as Mars colonies, hoppers, and biomass; space elevators and construction; and in-situ consumables. PMID:12506926

2002-12-01

138

Space Power  

NASA Technical Reports Server (NTRS)

Appropriate directions for the applied research and technology programs that will develop space power systems for U.S. future space missions beyond 1995 are explored. Spacecraft power supplies; space stations, space power reactors, solar arrays, thermoelectric generators, energy storage, and communication satellites are among the topics discussed.

1984-01-01

139

Space Missions  

NSDL National Science Digital Library

With three levels to choose from on each page - beginner, intermediate or advanced - this site provides in formation on past and current exploration ideas and achievements. The advances science has made in the space exploration area, such as having a permanent space station in space and the hundreds of probes, satellite, and space shuttles that have been launched. Advanced telescopes have given scientists the opportunity to see far beyond we ever imagined, and new explorations are found every day. Also featured are details about the International space station and what kinds of experiments scientists do in outer space.

Russell, Randy

2004-05-10

140

Space Toxicology.  

National Technical Information Service (NTIS)

Safe breathing air for space faring crews is essential whether they are inside an Extravehicular Mobility Suit (EMU), a small capsule such as Soyuz, or the expansive International Space Station (ISS). Sources of air pollution can include entry of propella...

J. T. James

2011-01-01

141

Space Survey  

NSDL National Science Digital Library

This is a lesson about society and space exploration. Learners will survey the public about their different opinions about space exploration and the use of robotics in space exploration. Then they will represent and analyze the results. This is lesson 5 of 16 in the MarsBots learning module.

142

Space Weather  

NASA Technical Reports Server (NTRS)

This video provides a narrated exploration of the history and affects of space weather. It includes information the earth's magnetic field, solar radiation, magnetic storms, and how solar winds affect electronics on earth, with specific information on how space weather affects space exploration in the future.

Gallagher, Dennis L.

2010-01-01

143

Space Sciences  

NSDL National Science Digital Library

Space Sciences contains information on the solar system, the Sun, Moon, and formation of the Earth as well as a wallpaper gallery of astronomical images. There are links to real-time astronomical data, a virtual tour of the International Space Station, star charts, the NASA space launch schedule, maps of the night sky, satellite data, an Earth and Moon viewer, and more.

144

Space weather  

NASA Astrophysics Data System (ADS)

Space weather is caused by conditions on the Sun and in the solar wind, the magnetosphere, ionosphere and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can affect human life or health. It affects man-made systems such as satellite electronics, terrestrial power grids and radio communications. This paper provides an overview of how space weather arises in the solar terrestrial system and how physical processes are able to cause space weather effects. We also discuss European perspectives and activities geared towards the possible initiation of a European Space Weather programme.

Glover, Alexi; Daly, Eamonn; Hilgers, Alain; Berghmans, David

2002-05-01

145

Space Commercialization  

NASA Technical Reports Server (NTRS)

A robust and competitive commercial space sector is vital to continued progress in space. The United States is committed to encouraging and facilitating the growth of a U.S. commercial space sector that supports U.S. needs, is globally competitive, and advances U.S. leadership in the generation of new markets and innovation-driven entrepreneurship. Energize competitive domestic industries to participate in global markets and advance the development of: satellite manufacturing; satellite-based services; space launch; terrestrial applications; and increased entrepreneurship. Purchase and use commercial space capabilities and services to the maximum practical extent Actively explore the use of inventive, nontraditional arrangements for acquiring commercial space goods and services to meet United States Government requirements, including measures such as public-private partnerships, . Refrain from conducting United States Government space activities that preclude, discourage, or compete with U.S. commercial space activities. Pursue potential opportunities for transferring routine, operational space functions to the commercial space sector where beneficial and cost-effective.

Martin, Gary L.

2011-01-01

146

Space law and space resources  

NASA Technical Reports Server (NTRS)

Space industrialization is confronting space law with problems that are changing old and shaping new legal principles. The return to the Moon, the next logical step beyond the space station, will establish a permanent human presence there. Science and engineering, manufacturing and mining will involve the astronauts in the settlement of the solar system. These pioneers, from many nations, will need a legal, political, and social framework to structure their lives and interactions. International and even domestic space law are only the beginning of this framework. Dispute resolution and simple experience will be needed in order to develop, over time, a new social system for the new regime of space.

Goldman, Nathan C.

1992-01-01

147

Hubble Space Telescope/Cosmic Origins Spectrograph Observations of the Quasar Q0302-003: Probing the He II Reionization Epoch and QSO Proximity Effects  

NASA Astrophysics Data System (ADS)

Q0302-003 (z = 3.2860 ± 0.0005) was the first quasar discovered that showed a He II Gunn-Peterson trough, a sign of incomplete helium reionization at z >~ 2.9. We present its Hubble Space Telescope/Cosmic Origins Spectrograph far-UV medium-resolution spectrum, which resolves many spectral features for the first time, allowing study of the quasar itself, the intergalactic medium, and quasar proximity effects. Q0302-003 has a harder intrinsic extreme-UV spectral index than previously claimed, as determined from both a direct fit to the spectrum (yielding ?? ? -0.8) and the helium-to-hydrogen ion ratio in the quasar's line-of-sight proximity zone. Intergalactic absorption along this sightline shows that the helium Gunn-Peterson trough is largely black in the range 2.87 < z < 3.20, apart from ionization due to local sources, indicating that helium reionization has not completed at these redshifts. However, we tentatively report a detection of nonzero flux in the high-redshift trough when looking at low-density regions, but zero flux in higher-density regions. This constrains the He II fraction to be about 1% in the low-density intergalactic medium (IGM) and possibly a factor of a few higher in the IGM as a whole, suggesting helium reionization has progressed substantially by z ~ 3.1. The Gunn-Peterson trough recovers to a He II Ly? forest at z < 2.87. We confirm a transmission feature due to the ionization zone around a z = 3.05 quasar just off the sightline, and resolve the feature for the first time. We discover a similar such feature possibly caused by a luminous z = 3.23 quasar further from the sightline, which suggests that this quasar has been luminous for >34 Myr.

Syphers, David; Shull, J. Michael

2014-03-01

148

Space America's commercial space program  

NASA Technical Reports Server (NTRS)

Space America prepared a private sector land observing space system which includes a sensor system with eight spectral channels configured for stereoscopic data acquisition of four stereo pairs, a spacecraft bus with active three-axis stabilization, a ground station for data acquisition, preprocessing and retransmission. The land observing system is a component of Space America's end-to-end system for Earth resources management, monitoring and exploration. In the context of the Federal Government's program of commercialization of the US land remote sensing program, Space America's space system is characteristic of US industry's use of advanced technology and of commercial, entrepreneurial management. Well before the issuance of the Request for Proposals for Transfer of the United States Land Remote Sensing Program to the Private Sector by the US Department of Commerce, Space Services, Inc., the managing venturer of Space America, used private funds to develop and manage its sub-orbital launch of its Conestoga launch vehicle.

Macleod, N. H.

1984-01-01

149

Learning Spaces  

NSDL National Science Digital Library

This website from EDUCAUSE includes the full text of the book Learning Spaces, edited by Diana G. Oblinger. Space, whether physical or virtual, can have a significant impact on learning. Learning Spaces focuses on how learner expectations influence such spaces, the principles and activities that facilitate learning, and the role of technology from the perspective of those who create learning environments: faculty, learning technologists, librarians, and administrators. Information technology has brought unique capabilities to learning spaces, whether stimulating greater interaction through the use of collaborative tools, videoconferencing with international experts, or opening virtual worlds for exploration. This e-book represents an ongoing exploration as we bring together space, technology, and pedagogy to ensure learner success.

Oblinger, Diana

2010-07-12

150

Space Telescopes  

NASA Technical Reports Server (NTRS)

Space telescopes have been a dominant force in astrophysics and astronomy over the last two decades. As Lyman Spitzer predicted in 1946, space telescopes have opened up much of the electromagnetic spectrum to astronomers, and provided the opportunity to exploit the optical performance of telescopes uncompromised by the turbulent atmosphere. This special section of Optical Engineering is devoted to space telescopes. It focuses on the design and implementation of major space observatories from the gamma-ray to far-infrared, and highlights the scientific and technical breakthroughs enabled by these telescopes. The papers accepted for publication include reviews of major space telescopes spanning the last two decades, in-depth discussions of the design considerations for visible and x-ray telescopes, and papers discussing concepts and technical challenges for future space telescopes.

Clampin, Mark; Flanagan, Kathryn A.

2012-01-01

151

Probability Spaces  

NSDL National Science Digital Library

Created by Kyle Siegrist of the University of Alabama-Huntsville, this is an online, interactive lesson on probability spaces. The resource provides examples, exercises, and applets that cover conditional probability, independence, and several modes of convergence that are appropriate for random variables. This section also covers probability space, the paradigm of a random experiment and its mathematical model as well as sample spaces, events, random variables, and probability measures. This is the second of seventeen different statistics lessons provided by Siegrist.

Siegrist, Kyle

2009-02-27

152

Spaced Out  

NSDL National Science Digital Library

Students are introduced to the space environment, learning about the major differences between the environment on Earth and that of outer space (atmosphere, radiation, microgravity) â and the engineering challenges that arise because of these differences. To prepare students for the upcoming lessons on the human body, they are challenged to think about how their bodies would change and adapt in the unique environment of space.

Integrated Teaching And Learning Program

153

Space Medicine  

NASA Technical Reports Server (NTRS)

The National Academy of Sciences Committee on Space Biology and Medicine points out that space medicine is unique among space sciences, because in addition to addressing questions of fundamental scientific interest, it must address clinical or human health and safety issues as well. Efforts to identify how microgravity affects human physiology began in earnest by the United States in 1960 with the establishment of the National Aeronautics and Space Administration (NASA's) Life Sciences program. Before the first human space missions, prediction about the physiological effects of microgravity in space ranged from extremely severe to none at all. The understanding that has developed from our experiences in space to date allows us to be guardedly optimistic about the ultimate accommodations of humans to space flight. Only by our travels into the microgravity environment of space have we begun to unravel the mysteries associated with gravity's role in shaping human physiology. Space medicine is still at its very earliest stages. Development of this field has been slow for several reasons, including the limited number of space flights, the small number of research subjects, and the competition within the life sciences community and other disciplines for flight opportunities. The physiological changes incurred during space flight may have a dramatic effect on the course of an injury or illness. These physiological changes present an exciting challenge for the field of space medicine: how to best preserve human health and safety while simultaneously deciphering the effects of microgravity on human performance. As the United States considers the future of humans in long-term space travel, it is essential that the many mysteries as to how microgravity affects human systems be addressed with vigor. Based on the current state of our knowledge, the justification is excellent indeed compelling- for NASA to develop a sophisticated capability in space medicine. Teams of physicians and scientists should be actively engaged in fundamental and applied research designed to ensure that it is safe for humans to routinely and repeatedly stay and work in the microgravity environment of space.

Pool, Sam L.

2000-01-01

154

Space Debris  

NSDL National Science Digital Library

This Wikipedia article provides information about space debris, the objects in orbit around Earth left over from earlier space missions. The article introduces the history of orbital debris production as well as the growing concern about collisions between this debris and functional satellites. Links provide further information.

2008-02-26

155

Amazing Space  

NSDL National Science Digital Library

This website is part of the Space Telescope Science Institute, and contains a set of interactive, web-based activities and lessons designed for classroom use. Topics include the Hubble Space Telescope, galaxies, comets, black holes, light, and the solar system.

156

Teaching space.  

NASA Astrophysics Data System (ADS)

Space technology teaching needs to be introduced at all levels of the educational process. The author already has wide experience in meeting this need in the USA, particularly in the St. Louis area, and is author of the teacher training manual, 'Space Education in the Classroom'.

Becker, T. W.

157

Space illusions  

Microsoft Academic Search

Reviews 20 publications dealing with space illusions (1909-1911). The topics include literature on the paradoxical illusion and the two point threshold, experience of feeling parts of the body lost by amputation, basis of reality judgments in hallucinations, Aristotelian illusion, illusion of filled and empty tactile space, after-image and limen hypotheses, geometrical optical illusions, and the like. H. A. Carr attributed

Harvey Carr

1911-01-01

158

Space Cardiology.  

National Technical Information Service (NTIS)

The present work deals with the problems of space medicine and contains some material relevant to the preservation of human health during space flight. An attempt is made to bring to a system the results of experimental investigations obtained during spac...

V. V. Parin R. M. Baevskii Y. N. Volkov O. G. Gazenko

1969-01-01

159

Space psychology  

NASA Technical Reports Server (NTRS)

Psychological selection of astronauts considers mental responses and adaptation to the following space flight stress factors: (1) confinement in a small space; (2) changes in three dimensional orientation; (3) effects of altered gravity and weightlessness; (4) decrease in afferent nerve pulses; (5) a sensation of novelty and danger; and (6) a sense of separation from earth.

Parin, V. V.; Gorbov, F. D.; Kosmolinskiy, F. P.

1974-01-01

160

Space shuttle  

NASA Technical Reports Server (NTRS)

The transportation cost associated with space materials processing were studied to determine the feasibility of space manufacturing. The assumptions use to determining the cost estimates for a 12 year planning period are listed, and the orbitor is described in terms of payloads. Shuttle operational costs, ground operational costs, and nonrecurring investment and development costs were analyzed.

1975-01-01

161

Space engineering  

NASA Technical Reports Server (NTRS)

Human productivity was studied for extravehicular tasks performed in microgravity, particularly including in-space assembly of truss structures and other large objects. Human factors research probed the anthropometric constraints imposed on microgravity task performance and the associated workstation design requirements. Anthropometric experiments included reach envelope tests conducted using the 3-D Acoustic Positioning System (3DAPS), which permitted measuring the range of reach possible for persons using foot restraints in neutral buoyancy, both with and without space suits. Much neutral buoyancy research was conducted using the support of water to simulate the weightlessness environment of space. It became clear over time that the anticipated EVA requirement associated with the Space Station and with in-space construction of interplanetary probes would heavily burden astronauts, and remotely operated robots (teleoperators) were increasingly considered to absorb the workload. Experience in human EVA productivity led naturally to teleoperation research into the remote performance of tasks through human controlled robots.

Alexander, Harold L.

1991-01-01

162

Space Weather  

NASA Astrophysics Data System (ADS)

Following James Van Allen's discovery of Earth's radiation belts (1958), it was immediately recognized that the space environment would be hostile to the communications satellites that had been envision by Arthur Clark (1945) and John Pierce (1955). Van Allen's discovery set off a burst of "space weather" research and engineering that continues to today, paralleling "space weather" research that had, prior to 1958, been directed toward understanding environment effects on cable and early wireless communications, electric power distribution, and pipelines. Van Allen's discovery also meant that the flight of humans above the sensible atmosphere would be fraught with more peril than mere weightlessness. This Van Allen lecture will discuss the space weather considerations that arose from Van Allen's discovery as well as space weather effects that occur from numerous other physical processes in the complex sun-heliosphere-magnetosphere environmental system.

Lanzerotti, L. J.

2005-05-01

163

Space Weather  

NASA Astrophysics Data System (ADS)

This volume provides a comprehensive overview of our current observational knowledge, theoretical understanding, and numerical capability with regard to the phenomena known as space weather. Space weather refers to conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems, and can endanger human life or health. The rapid advance in these technologies has provided us with unprecedented capability and convenience, and we have come to rely on them more and more. Technology has reduced society's risk to many kinds of natural disasters, but through its own vulnerability, it has actually increased society's risk to space weather. Adverse conditions in the space environment can cause disruption of satellite operations, communications, navigation, and electric power distribution grids, leading to a variety of socioeconomic losses.

Song, Paul; Singer, Howard J.; Siscoe, George L.

164

Space Shuttle  

NASA Technical Reports Server (NTRS)

A general description of the space shuttle program is presented, with emphasis on its application to the use of space for commercial, scientific, and defense needs. The following aspects of the program are discussed: description of the flight system (orbiter, external tank, solid rocket boosters) and mission profile, direct benefits related to life on earth (both present and expected), description of the space shuttle vehicle and its associated supporting systems, economic impacts (including indirect benefits such as lower inflation rates), listing of participating organizations.

1975-01-01

165

Space Weather  

NSDL National Science Digital Library

With three levels to choose from on each page - beginner, intermediate or advanced - this site provides information on Space Weather and the terms scientists use to describe the everchanging conditions in space. Explosions on the Sun create storms of radiation, fluctuating magnetic fields, and swarms of energetic particles. These phenomena travel outward through the Solar System with the solar wind. Upon arrival at Earth, they interact in complex ways with Earth's magnetic field, creating Earth's radiation belts and the Aurora. Some space weather storms can damage satellites, disable electric power grids, and disrupt cell phone communications systems. This site provides images, activities, and interesting facts about all of these events.

2004-02-06

166

Space Shuttle.  

ERIC Educational Resources Information Center

Presents an elementary teaching unit on NASA's space program, including teacher background information, suggested student activities, and a list of resources. Appended is a transcript of an interview conducted by elementary children with astronaut candidate Sherwood (Woody) Spring. (SJL)

Bierly, Ken; Dalheim, Mary

1981-01-01

167

Space Sense  

NSDL National Science Digital Library

Another great resource from the University of Michigan's Windows to the Universe Web site is the new Space Science activity. This interactive space trivia game tests your knowledge of space trivia with the goal to boost your rocket ship out of the atmosphere with correct answers. As with other Windows to the Universe resources, users get to choose the difficulty level they'd like to play and even between an adult and kids version of the game. Every question accompanies three answers from which to choose; when a correct answer is chosen, the rocket ship on the screen ascends towards outer space. Perhaps the most useful part of the activity is the "learn more" link that accompanies each answer, providing kids with a wealth of additional information and encouraging them to explore the subject further.

1995-01-01

168

Space Food.  

National Technical Information Service (NTIS)

In planning for the long duration Apollo missions, NASA conducted extensive research into space food. One of the techniques developed was freeze drying. Action Products commercialized this technique, concentrating on snack food including the first freeze-...

1994-01-01

169

Space Camera  

NASA Technical Reports Server (NTRS)

Nikon's F3 35mm camera was specially modified for use by Space Shuttle astronauts. The modification work produced a spinoff lubricant. Because lubricants in space have a tendency to migrate within the camera, Nikon conducted extensive development to produce nonmigratory lubricants; variations of these lubricants are used in the commercial F3, giving it better performance than conventional lubricants. Another spinoff is the coreless motor which allows the F3 to shoot 140 rolls of film on one set of batteries.

1983-01-01

170

Space Resources  

NASA Technical Reports Server (NTRS)

Space resources must be used to support life on the Moon and exploration of Mars. Just as the pioneers applied the tools they brought with them to resources they found along the way rather than trying to haul all their needs over a long supply line, so too must space travelers apply their high technology tools to local resources. The pioneers refilled their water barrels at each river they forded; moonbase inhabitants may use chemical reactors to combine hydrogen brought from Earth with oxygen found in lunar soil to make their water. The pioneers sought temporary shelter under trees or in the lee of a cliff and built sod houses as their first homes on the new land; settlers of the Moon may seek out lava tubes for their shelter or cover space station modules with lunar regolith for radiation protection. The pioneers moved further west from their first settlements, using wagons they had built from local wood and pack animals they had raised; space explorers may use propellant made at a lunar base to take them on to Mars. The concept for this report was developed at a NASA-sponsored summer study in 1984. The program was held on the Scripps campus of the University of California at San Diego (UCSD), under the auspices of the American Society for Engineering Education (ASEE). It was jointly managed under the California Space Inst. and the NASA Johnson Space Center, under the direction of the Office of Aeronautics and Space Technology (OAST) at NASA Headquarters. The study participants (listed in the addendum) included a group of 18 university teachers and researchers (faculty fellows) who were present for the entire 10-week period and a larger group of attendees from universities, Government, and industry who came for a series of four 1-week workshops. The organization of this report follows that of the summer study. Space Resources consists of a brief overview and four detailed technical volumes: (1) Scenarios; (2) Energy, Power, and Transport; (3) Materials; (4) Social Concerns. Although many of the included papers got their impetus from workshop discussions, most have been written since then, thus allowing the authors to base new applications on established information and tested technology. All these papers have been updated to include the authors' current work. This overview, drafted by faculty fellow Jim Burke, describes the findings of the summer study, as participants explored the use of space resources in the development of future space activities and defined the necessary research and development that must precede the practical utilization of these resources. Space resources considered included lunar soil, oxygen derived from lunar soil, material retrieved from near-Earth asteroids, abundant sunlight, low gravity, and high vacuum. The study participants analyzed the direct use of these resources, the potential demand for products from them, the techniques for retrieving and processing space resources, the necessary infrastructure, and the economic tradeoffs. This is certainly not the first report to urge the utilization of space resources in the development of space activities. In fact, Space Resources may be seen as the third of a trilogy of NASA Special Publications reporting such ideas arising from similar studies. It has been preceded by Space Settlements: A Design Study (NASA SP-413) and Space Resources and Space Settlements (NASA SP-428). And other, contemporaneous reports have responded to the same themes. The National Commission on Space, led by Thomas Paine, in Pioneering the Space Frontier, and the NASA task force led by astronaut Sally Ride, in Leadership and America's Future in Space, also emphasize expansion of the space Infrastructure; more detailed exploration of the Moon, Mars, and asteroids; an early start on the development of the technology necessary for using space resources; and systematic development of the skills necessary for long-term human presence in space. Our report does not represent any Government-authorized view or official NASA policy. NASA's official response to these challenging op

McKay, Mary Fae (Editor); McKay, David S. (Editor); Duke, Michael S. (Editor)

1992-01-01

171

Space Debris  

NSDL National Science Digital Library

This Topic in Depth begins with a Web site maintained by Dr. Richard B. Gomez of George Mason University called Space Debris (1). The site is offered as a slide presentation, which explains what space debris is, where it comes from, if it's dangerous, what is known about it, and what can be done about it. The very interesting site is perfect for non-experts because of its simple descriptions and abundance of graphics. The second site from Space.com is an article written by Robert Roy Britt entitled Space Junk: The Stuff Left Behind (2). Visitors can read about the number of objects being tracked (at the time the article was written), what the total weight of these objects is, view a table of the number of various pieces of space junk by country, and even find out it if there is a risk of getting hit in the head by these objects. The next site, Nature's Tiniest Space Junk (3), is offered by NASA's news portal Science@NASA Web site. The page describes how scientists are monitoring tiny dust sized meteoroids that are constantly flying around our planet that have the potential to be quite dangerous. For those really interested, the site lets people listen to audio files of the meteor radar in action. The fourth site on space junk, maintained by the Texas Advanced Computing Center, is a Simulation of Orbital Debris Shielding Performance at High Impact Velocities (4). The page highlights the work of Dr. Eric Fahrenthold, who is simulating orbital debris shielding performance at high impact velocities. A basic description of the work is offered along with the simulation itself, which shows a piece of space debris striking a surface. Next, from NASA's Hazards Assessment Web site, comes the Hypervelocity Impact Test Facility: Orbital Debris and Micrometeoroids (5) page. Readers can find out more on the problem of space junk, why NASA feels its so important to study simulating particle impacts on spacecraft, the lightweight shields that are in place on the International Space Station, and more. The sixth site is an article that appeared in the Bulletin of the Atomic Scientists by Joel Primack called Pelted by Paint, Downed by Debris (6). Although there's not a large amount of content on the site, it does give some interesting information on a different aspect of the subject. The author describes how any missile defense program could be detrimentally affected by space debris and suggests the need for space agencies to take active steps to prevent its buildup. The National Academies Press offers the next site, which is actually an online book on Protecting the Space Station from Meteoroids and Orbital Debris (7). Contents include risk management strategies for the space station, debris modeling, shielding the station, collision warning and avoidance, and more. The last site is from the Aerospace Corporation and its Center for Orbital and Reentry Debris Studies (8). Visitors will find an introduction to the Center, the basics of space debris, what happens during satellite reentry, re-entry data and predictions, additional links, and more.

Brieske, Joel A.

2003-01-01

172

Space Rescue  

NASA Technical Reports Server (NTRS)

Space Rescue has been a topic of speculation for a wide community of people for decades. Astronauts, aerospace engineers, diplomats, medical and rescue professionals, inventors and science fiction writers have all speculated on this problem. Martin Caidin's 1964 novel Marooned dealt with the problems of rescuing a crew stranded in low earth orbit. Legend at the Johnson Space Center says that Caidin's portrayal of a Russian attempt to save the American crew played a pivotal role in convincing the Russians to join the real joint Apollo-Soyuz mission. Space Rescue has been a staple in science fiction television and movies portrayed in programs such as Star Trek, Stargate-SG1 and Space 1999 and movies such as Mission To Mars and Red Planet. As dramatic and as difficult as rescue appears in fictional accounts, in the real world it has even greater drama and greater difficulty. Space rescue is still in its infancy as a discipline and the purpose of this chapter is to describe the issues associated with space rescue and the work done so far in this field. For the purposes of this chapter, the term space rescue will refer to any system which allows for rescue or escape of personnel from situations which endanger human life in a spaceflight operation. This will span the period from crew ingress prior to flight through crew egress postlanding. For the purposes of this chapter, the term primary system will refer to the spacecraft system that a crew is either attempting to escape from or from which an attempt is being made to rescue the crew.

Muratore, John F.

2007-01-01

173

BBC Space  

NSDL National Science Digital Library

Hosted by the British Broadcasting Corporation (BBC), this site provides comprehensive information about space science. There is the latest news about space findings and issues, and what's happening in the sky for the current month. Galleries show images of the planets, Sunspots, eclipses, auroras, and more. There is a night sky section with observation notes and a constellation guide for learning more about the star patterns. 'Deep Space' covers phenomena such as black holes, wormholes, and dark matter. There is a discussion covering the possibility of life elsewhere, planets outside of our Solar System, and astrobiology. 'Origins' explores the Big Bang, from the first few seconds to the future. 'Cosmology' discusses how our ideas about the Earth and Universe have grown and continue to expand. The stars section illustrates different star types, and the life of stars from birth to death. There is also a section of brief biographies on all astronomers who have contributed to our current knowledge of space, such as Galileo, Copernicus, Ptolemy, Hubble, and many more. There are links to additional sites, as well as space games to play.

174

Space Telescopes  

NASA Technical Reports Server (NTRS)

The science of astronomy depends on modern-day temples called telescopes. Astronomers make pilgrimages to remote mountaintops where these large, intricate, precise machines gather light that rains down from the Universe. Bit, since Earth is a bright, turbulent planet, our finest telescopes are those that have been launched into the dark stillness of space. These space telescopes, named after heroes of astronomy (Hubble, Chandra, Spitzer, Herschel), are some of the best ideas our species has ever had. They show us, over 13 billion years of cosmic history, how galaxies and quasars evolve. They study planets orbiting other stars. They've helped us determine that 95% of the Universe is of unknown composition. In short, they tell us about our place in the Universe. The next step in this journey is the James Webb Space Telescope, being built by NASA, Europe, and Canada for a 2018 launch; Webb will reveal the first galaxies that ever formed.

Rigby, Jane R.

2011-01-01

175

Entering Space  

NASA Astrophysics Data System (ADS)

The authors is giving a classification of civilisations depending on the degree of colonisation of the Earth, Solar System and Our Galaxy. The problems of: History of geographic discoveries (The great geographical discoveries during the Middle Age, the concurence of Chinnese and Europeans in this Area); The Astrophysics, such as: Asteroids, Water and Atmosphere on outer planets, Planet Mars Planet, Agriculture on outer planets, Minerals on outer planets; Cosmic flights: Fuels, Robotics, Moon (as an intermediary basis for interplanetary flights), Mars colonisation; Interstellar flights, Space research costs, strategy and tactics of the space colonisation; Policy: War and Peace, International Collaboration are discussed.

Zubrin, Robert

176

Second Symposium on Space Industrialization. [space commercialization  

NASA Technical Reports Server (NTRS)

The policy, legal, and economic aspects of space industrialization are considered along with satellite communications, material processing, remote sensing, and the role of space carriers and a space station in space industrialization.

Jernigan, C. M. (editor)

1984-01-01

177

Space internetworking with CCSDS Space Packets  

NASA Astrophysics Data System (ADS)

Some space agencies are planning to launch constellations of space elements for space exploration or space science programs. In these constellations, some spacecraft are sometimes required to relay data to and from other spacecraft. In constellations having such relay spacecraft, the capability of space internetworking is required because the onboard networks of the participating spacecraft must be interconnected. Most current space projects use CCSDS Space Packets for data transfer, but CCSDS Space Packets do not have a capability for performing space internetworking. This paper proposes a method for realizing space internetworking using CCSDS Space Packets with only a minor modification. The method proposed in this paper uses the technique of encapsulating Space Packets into other Space Packets. This method has several advantages over using special protocols for realizing space internetworking: (1) this method enables development of space internetworking with a very small cost; (2) this method is scalable; and (3) this method facilitates interoperability among different space agencies.

Yamada, T.

178

Space Pharmacy.  

National Technical Information Service (NTIS)

Functional disorders and illnesses which could occur during space flight are considered in terms of preparation of a first-aid kit. Contents of the kit are discussed as well as instructions and training in the use of the kit. (Author)

I. Fedorov

1976-01-01

179

Space Gerontology  

NASA Technical Reports Server (NTRS)

Presentations are given which address the effects of space flght on the older person, the parallels between the physiological responses to weightlessness and the aging process, and experimental possibilities afforded by the weightless environment to fundamental research in gerontology and geriatrics.

Miquel, J. (editor); Economos, A. C. (editor)

1982-01-01

180

Appealing Spaces  

ERIC Educational Resources Information Center

For more than a decade, educators and designers have been moving tentatively into uncharted waters. This article reports that administrators, faculty, and planners now recognize that learning spaces should be developed for reasons beyond utilization numbers. With declining retention and graduation rates, education institutions are acknowledging…

Dittoe, William; Porter, Nat

2007-01-01

181

Training Spaces  

ERIC Educational Resources Information Center

Creating a balanced learning space for employees is about more than trying different types of seating. It is a challenge that an affect how well employees absorb the lessons and whether they will be able to product better results for the company. The possible solutions are as diverse as the learners. This article describes how three companies…

Weinstein, Margery

2010-01-01

182

Children's Space  

ERIC Educational Resources Information Center

Evidence of the ways in which children utilise neighbourhood spaces for play and socalising is presented here. Findings are based on research conducted on the social and environmental geographies of children in middle childhood in Fife, Scotland. Photographs and maps produced by the children are used to illustrate their active, emotional and…

Ross, Nicola J.

2005-01-01

183

Space illusions  

Microsoft Academic Search

Reviews 5 studies dealing with space illusions (1915). A three-fold classification of illusions, based on their stability under critical examination, has been proposed. A new illusion has also been reported. Vaihinger's interpretation of Kant's concepts of error, reality, illusion, and hallucination has been critiqued. The illusion of the overestimation of the lower of 2 twin stars by astronomers has been

Harvey Carr

1916-01-01

184

Trading Spaces  

ERIC Educational Resources Information Center

Education administrators face the dual dilemma of crowded, aging facilities and tightening capital budgets. The challenge is to build the necessary classroom, laboratory and activity space while minimizing the length and expense of the construction process. One solution that offers an affordable alternative is modular construction, a method that…

Cort, Cliff

2006-01-01

185

Space languages  

NASA Technical Reports Server (NTRS)

Applications of linguistic principles to potential problems of human and machine communication in space settings are discussed. Variations in language among speakers of different backgrounds and change in language forms resulting from new experiences or reduced contact with other groups need to be considered in the design of intelligent machine systems.

Hays, Dan

1987-01-01

186

Reserving Space.  

ERIC Educational Resources Information Center

Presents the criteria schools can use to evaluate furniture and casework in K-12 educational spaces. Tips include keeping furniture or casework flexible in its placement, making color schemes simple, and minimizing use of built-in casework for administrative stations and offices. (GR)

Greischar, Kevin

1999-01-01

187

Found Space  

ERIC Educational Resources Information Center

When education providers confront obstacles such as shrinking budgets and swelling enrollments, a multi-million-dollar new facility or major additions probably are not feasible. Converting vacant and underused buildings into school facilities enables administrators to acquire additional space quickly and cheaply. In this article, the authors…

Haug, Ted; Ogurek, Douglas J.

2006-01-01

188

Inherit Space  

NASA Technical Reports Server (NTRS)

The objective of the proposed research was to begin development of a unique educational tool targeted at educating and inspiring young people 12-16 years old about NASA and the Space Program. Since these young people are the future engineers, scientists and space pioneers, the nurturing of their enthusiasm and interest is of critical importance to the Nation. This summer the basic infrastructure of the tool was developed in the context of an educational game paradigm. The game paradigm has achieved remarkable success in maintaining the interest of young people in a self-paced, student-directed learning environment. This type of environment encourages student exploration and curiosity which are exactly the traits that future space pioneers need to develop to prepare for the unexpected. The Inherit Space Educational Tool is an open-ended learning environment consisting of a finite-state machine classic adventure game paradigm. As the young person explores this world, different obstacles must be overcome. Rewards will be offered such as using the flight simulator to fly around and explore Titan. This simulator was modeled on conventional Earth flight simulators but has been considerably enhanced to add texture mapping of Titan's atmosphere utilizing the latest information from the NASA Galileo Space Probe. Additional scenery was added to provide color VGA graphics of a futuristic research station on Titan as well as an interesting story to keep the youngster's attention. This summer the game infrastructure has been developed as well as the Titan Flight Simulator. A number of other enhancements are planned.

Giarratano, Joseph C.; Jenks, K. C.

1997-01-01

189

Space Sciences  

NSDL National Science Digital Library

The latest addition to the Office of Naval Research's Science & Technology Focus site (last mentioned in March 29, 2002 Scout Report) is the Space Sciences Page. The site contains the Observing the Sky link, which has easily read information, photographs, and illustrations on earth rotation, orbit, seasons, observing stars, and more. The Navy & Satellites link describes the Navy's role in launching satellites and how that's accomplished while additional facts can be found on the Naval Research page.

1969-12-31

190

Space colonization.  

PubMed

A series of workshops were sponsored by the Physical Science Division of NASA's Office of Biological and Physical Research to address operational gravity-compliant in-situ resource utilization and life support techologies. Workshop participants explored a Mars simulation study on Devon Island, Canada; the processing of carbon dioxide in regenerative life support systems; space tourism; rocket technology; plant growth research for closed ecological systems; and propellant extraction of planetary regoliths. PMID:14696587

Parrish, Clyde F

2003-12-01

191

Communication spaces  

PubMed Central

Background and objective Annotations to physical workspaces such as signs and notes are ubiquitous. When densely annotated, work areas become communication spaces. This study aims to characterize the types and purpose of such annotations. Methods A qualitative observational study was undertaken in two wards and the radiology department of a 440-bed metropolitan teaching hospital. Images were purposefully sampled; 39 were analyzed after excluding inferior images. Results Annotation functions included signaling identity, location, capability, status, availability, and operation. They encoded data, rules or procedural descriptions. Most aggregated into groups that either created a workflow by referencing each other, supported a common workflow without reference to each other, or were heterogeneous, referring to many workflows. Higher-level assemblies of such groupings were also observed. Discussion Annotations make visible the gap between work done and the capability of a space to support work. Annotations are repairs of an environment, improving fitness for purpose, fixing inadequacy in design, or meeting emergent needs. Annotations thus record the missing information needed to undertake tasks, typically added post-implemented. Measuring annotation levels post-implementation could help assess the fit of technology to task. Physical and digital spaces could meet broader user needs by formally supporting user customization, ‘programming through annotation’. Augmented reality systems could also directly support annotation, addressing existing information gaps, and enhancing work with context sensitive annotation. Conclusions Communication spaces offer a model of how work unfolds. Annotations make visible local adaptation that makes technology fit for purpose post-implementation and suggest an important role for annotatable information systems and digital augmentation of the physical environment.

Coiera, Enrico

2014-01-01

192

Space Nutrition  

NASA Technical Reports Server (NTRS)

Optimal nutrition will be critical for crew members who embark on space exploration missions. Nutritional assessment provides an opportunity to ensure that crewmembers begin their missions in optimal nutritional status, to document changes during a mission and, if necessary, to provide intervention to maintain that status throughout the mission, and to assesses changes after landing in order to facilitate the return to their normal status as soon as possible after landing. We report here the findings from our nutritional assessment of astronauts who participated in the International Space Station (ISS) missions, along with flight and ground-based research findings. We also present ongoing and planned nutrition research activities. These studies provide evidence that bone loss, compromised vitamin status, and oxidative damage are the critical nutritional concerns for space travelers. Other nutrient issues exist, including concerns about the stability of nutrients in the food system, which are exposed to longterm storage and radiation during flight. Defining nutrient requirements, and being able to provide and maintain those nutrients on exploration missions, will be critical for maintaining crew member health.

Smith, Scott M.

2009-01-01

193

America plans for space  

SciTech Connect

Contents include: pursuing a balanced space program; the space defense initiative; warfare in space; the lunar laboratory; the role of space in preserving the peace; living off the land - the use of resources in space for future civilian space operations; the military uses of space; C3I(command control communications and intelligence); aspects of space technology; arms control in space: preserving critical strategic space systems without weapons in space; space and arms control: a skeptical view; options for space arms control; space arms control.

Not Available

1986-01-01

194

Space Audio  

NSDL National Science Digital Library

This site offers the "sounds of space" processed from signals received by University of Iowa instruments on various spacecraft. The collection includes sounds from Saturn collected by the Cassini probe, sounds from the edge of the solar system collected by the Voyager probe, as well as radio bursts from solar flares and sounds created by Earth's magnetosphere. There are also descriptions of several types of sounds (whistlers, choruses, and auroral radio emissions) and sample sounds produced by processed data received from specific spacecraft (Galileo, Polar, Cassini, Cluster, and others).

195

Space Food  

NASA Technical Reports Server (NTRS)

In planning for the long duration Apollo missions, NASA conducted extensive research into space food. One of the techniques developed was freeze drying. Action Products commercialized this technique, concentrating on snack food including the first freeze-dried ice cream. The foods are cooked, quickly frozen and then slowly heated in a vacuum chamber to remove the ice crystals formed by the freezing process. The final product retains 98 percent of its nutrition and weighs only 20 percent of its original weight. Action snacks are sold at museums, NASA facilities and are exported to a number of foreign countries. Sales run to several million dollars annually.

1994-01-01

196

Loop space  

NASA Astrophysics Data System (ADS)

Several topics in the loop-space formulation of non-Abelian gauge theories are considered. The basic objects dealt with are the unrenormalized dimensionally regularized gauge-invariant loop functions W(Cig, ?), where Ci is a set of loops, g is the unrenormalized coupling constant, and ? is the deviation from four space-time dimensions. The renormalization-group equations satisfied by the corresponding renormalized loop functions are derived and, using asymptotic freedom, used to determine the exact behavior of the functions when the length L of the loops approaches zero. The result is (-lnL?)a(?), where ? is the subtraction mass and ? represents the cusp and cross-point angles of the loops. The function a(?) is exactly computable and several examples are given. The equivalent result may be stated as the exact behavior of the renormalization-constant matrix Zij(?, gR, ?) for ?-->0 with fixed renormalized coupling constant gR, or as the exact behavior of the unrenormalized loop function for ?-->0 and gR fixed. It is shown next that the W(Cig, ?) satisfy dimensionally regularized Makeenko-Migdal equations in all orders of perturbation theory. The proof makes detailed use of dimensional regularization, Becchi-Rouet-Stora symmetry, gauge-field combinatorics, and properties of the area functional derivative of path-ordered multiple line integrals. Doubt is cast on the existence of such useful equations when other regularizations are used or when renormalization is performed. The Mandelstam constraints are considered next. Among other things, it is shown that the loop-function renormalization may be performed such that the renormalized functions satisfy a constraint which has the same form as the unrenormalized constraint i=1(N+1)?aiW(Ci)=0, for the U(N) gauge group. The paper concludes with illustrations of how observable matrix elements of physical (color singlet, quark bilinear) flavor currents may be expressed in terms of loop functions. Among other topics discussed in the paper are the N-->? limit, two-dimensional QCD, and normalization conditions on the renormalized loop functions.

Brandt, R. A.; Gocksch, A.; Sato, M.-A.; Neri, F.

1982-12-01

197

8 Meter Advanced Technology Large-Aperture Space Telescope (ATLAST-8m)  

NASA Technical Reports Server (NTRS)

ATLAST-8m (Advanced Technology Large Aperture Space Telescope) is a proposed 8-meter monolithic UV/optical/NIR space observatory (wavelength range 110 to 2500 nm) to be placed in orbit at Sun-Earth L2 by NASA's planned Ares V heavy lift vehicle. Given its very high angular resolution (15 mas @ 500 nm), sensitivity and performance stability, ATLAST-8m is capable of achieving breakthroughs in a broad range of astrophysics including: Is there life elsewhere in the Galaxy? An 8-meter UVOIR observatory has the performance required to detect habitability (H2O, atmospheric column density) and biosignatures (O2, O3, CH4) in terrestrial exoplanet atmospheres, to reveal the underlying physics that drives star formation, and to trace the complex interactions between dark matter, galaxies, and intergalactic medium. The ATLAST Astrophysics Strategic Mission Concept Study developed a detailed point design for an 8-m monolithic observatory including optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; mass and power budgets; and system cost. The results of which were submitted by invitation to NRC's 2010 Astronomy & Astrophysics Decadal Survey.

Stahl, H. Philip

2010-01-01

198

Space Science in Action: Space Exploration [Videotape].  

ERIC Educational Resources Information Center

In this videotape recording, students learn about the human quest to discover what is out in space. Students see the challenges and benefits of space exploration including the development of rocket science, a look back at the space race, and a history of manned space travel. A special section on the Saturn V rocket gives students insight into the…

1999

199

Space weather and deep space communications  

Microsoft Academic Search

While Pioneer 11 and Galileo are two deep space missions that experienced radio communication disruptions due to space weather, the success of a mission like Solar Probe, whose goal is to fly by the Sun within a few solar radii of its surface, may depend critically on space weather. It is therefore crucial to thoroughly understand how space weather affects

Richard Woo

2007-01-01

200

International Space Station: Don Pettit Space Chronicles  

NSDL National Science Digital Library

This site from NASAâs Human Space Flight program contains the observations and reflections of ISS Science Officer Don Pettit while on board the International Space Station. The journal-style entries describe living and working in space, including the preparations for a space walk. The site also offers videos of Pettitâs Saturday Morning Science experiments.

2006-09-29

201

Equally Spaced?  

NSDL National Science Digital Library

Urbanologists and other types have been interested in the interactions between different groups of people in cities for hundreds of years. There is quite a broad literature on studying different types of communities and public spaces, and this recent paper from the Demos group in the United Kingdom adds to that body of work. This 40-page report was first published in July 2007, and it was authored by Hannah Lownsbrough and Joost Beunderman. As the report's subtitle suggests, it is primarily concerned with presenting a dynamic look at how public places can effectively encourage interaction between diverse communities in urban areas. For this work, the researchers looked at three separate locations in Britain, and this report presents some of their findings on what works well (and not so well) in terms of creating and maintaining high-quality public places. The report is both thoughtful and thorough, and persons with an interest in urban planning, sociology, and related fields will find it quite compelling.

Beunderman, Joost; Lownsbrough, Hannah

2007-07-01

202

Space physiology and medicine  

SciTech Connect

The state of knowledge in space physiology and medicine are reviewed. Overviews of manned space flight, the space environment, spaceflight systems and procedures, physiological adaptation to space flight, health maintenance of space crew members, and medical problems of space flight are presented.

Nicogossian, A.E.; Parker J.F. Jr.

1982-01-01

203

On homogeneous Finsler spaces  

NASA Astrophysics Data System (ADS)

In this paper we study homogeneous Finsler spaces and show that they are forward complete. As a special case we consider homogeneous Randers spaces and show that if these spaces have constant flag curvature then the underlying Riemannian space is locally symmetric. Also we extend some of classical results in Riemannian homogeneous spaces to those in homogeneous Finsler spaces.

Latifi, Dariush; Razavi, Asadollah

2006-06-01

204

Space habitats. [prognosis for space colonization  

NASA Technical Reports Server (NTRS)

Differences between space industrialization and space colonization are outlined along with the physiological, psychological, and esthetic needs of the inhabitants of a space habitat. The detrimental effects of zero gravity on human physiology are reviewed, and the necessity of providing artificial gravity, an acceptable atmosphere, and comfortable relative humidity and temperature in a space habitat is discussed. Consideration is also given to social organization and governance, supply of food and water, and design criteria for space colonies.

Johnson, R. D.

1978-01-01

205

The Intergalactic Medium as a Cosmological Tool  

NASA Astrophysics Data System (ADS)

In this talk I will review the capabilities of high-resolution (UVES and Keck) and low resolution (Sloan Digital Sky Survey - SDSS) quasar (QSO) Lyman-? absorption spectra as cosmological tools to probe the dark matter distribution in the high redshift universe. I will first summarize the results in terms of cosmological parameters and then discuss consistency with the parameters derived from other large scale structure observable such as the Cosmic Microwave Background (CMB) and weak lensing surveys. When the Lyman-? forest data are combined with CMB data and the weak lensing results of the z-COSMOS survey the constraints are: ?=0.800±0.023, n=0.971±0.011?=0.247±0.016 (1-? error bars), in perfect agreement with the CMB results of WMAP year five alone. I will briefly address the importance of Lyman-? for constraining the neutrino mass fraction. Furthermore, I will present constraints on the mass of warm dark matter (WDM) particles derived from the Lyman-? flux power spectrum of 55 high-resolution HIRES Lyman-? forest spectra at 2.0

Viel, Matteo

2009-10-01

206

Extragalactic Radio Jets and Intergalactic Medium 2  

NASA Technical Reports Server (NTRS)

During the mid 1990s, the ROSAT satellite provided the highest resolution X-ray imaging, with useful X-ray spectroscopy, and excellent sensitivity. ROSAT"s PSPC and HRI instruments gave us our first high-quality data on the AGN phenomenon in nearby galaxies - the central theme of this research project. Initially this project concentrated on separating the AGN-related component of the X-ray emission from thermal radiation from the surrounding atmospheres in radio galaxies. There was ample reason to believe that this separation would be possible, although earlier work had taken the view that the X-ray emission from radio galaxies is either wholly AGN-related (and hence of sub-arcsec scale), or wholly from the galaxy and cluster atmospheres (and hence of scales - 10 arcsec or more in the low-redshift radio galaxies that we chose to study). First with the PSPC, and then with the HRI, we proved that a wide range of AGN core X ray emissivities could be found, and that the generic radio galaxy produces both AGN-related and atmosphere-related X-radiation. We demonstrated that there is a close relationship between the core X-ray power and the core radio power, and found instances in which the hot atmospheres of the galaxies must be participating in cooling flows, and other cases where those atmospheres are relatively stable. In some cases, there is a clear active relationship between the extended radio emission and the X-ray atmospheres: thus in NGC 326, we interpret the distorted radio structure as evidence of buoyancy as the radio plasma rises through the cluster atmosphere. In 3C 449, we can see that the radio plasma is displacing the X-ray emitting gas. In a further case (NGC 1265), we hoped that the motion of a radio galaxy through a cluster atmosphere would be apparent though the wake that it might establish - unfortunately, other structure in the atmosphere of the Perseus cluster tends to dominate our X-ray image, and no useful limits could be placed on the strength of the wake. In the light of so-called "unified" models of AGN, it is expected that the low-power radio galaxies studied under these programmes are the unbeamed counterparts of BL Lac objects. Accordingly, we predicted that BL Lac objects, as a class, should show X-ray halos from atmospheres similar to those associated with radio galaxies. The difficulty with studying this is that BL Lac objects tend to be X-ray bright, and the halos then vanish under the wings of the point response function. We found a BL Lac with less of a dynamic range problem, mapped it with the ROSAT HRI, and duly found an atmosphere (Hardcastle et al. 1999). Unfortunately for unification models, this atmosphere is exceptionally dense, so that it must be participating in an intense cooling flow. The implications of this for unification models are far from clear, and further work is under way.

Birkinshaw, Mark

2000-01-01

207

"Space, the Final Frontier"; Books on Space and Space Exploration.  

ERIC Educational Resources Information Center

Advocates play in a child's life. Describes how science fiction seizes the imaginations of young readers with its tales of the future and of outer space. Talks about various nonfiction books about space. Elaborates a workshop on books about space exploration. Gives 10 questions about stimulating student response. (PA)

Jordan, Anne Devereaux

1997-01-01

208

46 CFR 108.205 - Wash spaces; toilet spaces; and shower spaces.  

Code of Federal Regulations, 2010 CFR

...false Wash spaces; toilet spaces; and shower spaces...205 Wash spaces; toilet spaces; and shower spaces...Private facilityâ means a toilet, washing, or shower space that is...water. (j) Adjacent toilets must be separated...

2010-10-01

209

European Space Science and Space Station Freedom.  

National Technical Information Service (NTIS)

Six instruments for space sciences are presented as potential external payloads, which need accommodation on the Space Station Freedom (SSF) truss or on the Columbus Attached Laboratory (CAL) by means of a terrace or balcony: SUN (an interferometer with a...

P. L. Bernacca

1992-01-01

210

Use of Space Station for Space Science.  

National Technical Information Service (NTIS)

Space Station cornerstone and other space science missions are outlined. The cornerstone missions are the comet nucleus sample return mission and the submillimeter heterodyne spectroscopy mission. Gamma ray spectroscopy, cosmic ray background anisotropy m...

G. P. Haskell

1987-01-01

211

Standard RGB Color Spaces  

Microsoft Academic Search

This paper describes the specifications and usage of standard RGB color spaces promoted today by standard bodies and\\/or the imaging industry. As in the past, most of the new standard RGB color spaces were developed for specific imaging workflow and applications. They are used as interchange spaces to communicate color and\\/or as working spaces in imaging applications. Standard color spaces

Sabine Süsstrunk; Robert Buckley; Steve Swen

1999-01-01

212

Space on Earth.  

ERIC Educational Resources Information Center

Describes ideas for applying research from space programs to life science instruction including plants in space, exercise and diet on space flights, environmental advantages from space exploration, and the effects of microgravity on health. Discusses space spinoffs used in medicine including digital imaging processing and the Ingestible Thermal…

Leder, Sandra J.

1992-01-01

213

Canada in Space.  

ERIC Educational Resources Information Center

Discusses the history of the Canadian Space Agency. Explains that Canada's space program grew out of the need to manage resources and communicate over large distances. Reports that the small Canadian space industry is growing rapidly. Describes Canadian cooperation in international space programs. Identifies space careers and examines the future…

de Paz, Shoshana

1991-01-01

214

Space Station propulsion system  

NASA Astrophysics Data System (ADS)

Viewgraphs on space station propulsion systems are presented. Topics covered include: space station propulsion system requirements; space station propulsion system design; space station propulsion system drivers; hydrazine technology development; waste fluid disposal system; space station propulsion system evolution; propellant selection trade study; technology needs to water electrolysis/oxygen-hydrogen propulsion system; and technology needs for bipropellant systems.

Henderson, J.

215

Space-to-Space Communications System  

NASA Technical Reports Server (NTRS)

The Space-to-Space Communications System (SSCS) is an Ultra High Frequency (UHF) Time-Division-Multiple Access (TDMA) system that is designed, developed, and deployed by the NASA Johnson Space Center (JSC) to provide voice, commands, telemetry and data services in close proximity among three space elements: International Space Station (ISS), Space Shuttle Orbiter, and Extravehicular Mobility Units (EMU). The SSCS consists of a family of three radios which are, Space-to-Space Station Radio (SSSR), Space-to-Space Orbiter Radio (SSOR), and Space-to-Space Extravehicular Mobility Radio (SSER). The SSCS can support up to five such radios at a time. Each user has its own time slot within which to transmit voice and data. Continuous Phase Frequency Shift Keying (CPFSK) carrier modulation with a burst data rate of 695 kbps and a frequency deviation of 486.5 kHz is employed by the system. Reed-Solomon (R-S) coding is also adopted to ensure data quality. In this paper, the SSCS system requirements, operational scenario, detailed system architecture and parameters, link acquisition strategy, and link performance analysis will be presented and discussed

Tu, Kwei; Gaylor, Kent; Vitalpur, Sharada; Sham, Cathy

1999-01-01

216

Space history, space policy, and executive leadership  

NASA Technical Reports Server (NTRS)

A lecture that attempts to establish the role of space historians in formulating space policy is presented. The discussion focusses on two adages and their relevance to space policy. The adages are as follows: 'write about what you know;' and 'good managers do things right; good executives do the right things.'

Kraemer, Sylvia K.

1993-01-01

217

Space Strategy Considerations for Medium Space Powers  

Microsoft Academic Search

When compared to the strategies of superpowers, the strategies of medium powers are often different due to a medium power's frequent desire to act independently while being comparatively more constrained by available material and fiscal resources. For this reason, the space strategy of medium space powers is different from either emerging or super space powers. The fundamental purpose of any

John J. Klein

2012-01-01

218

Space Solar Power Program  

SciTech Connect

Information pertaining to the Space Solar Power Program is presented on energy analysis; markets; overall development plan; organizational plan; environmental and safety issues; power systems; space transportation; space manufacturing, construction, operations; design examples; and finance.

Arif, H.; Barbosa, H.; Bardet, C.; Baroud, M.; Behar, A.; Berrier, K.; Berthe, P.; Bertrand, R.; Bibyk, I.; Bisson, J.; Bloch, L.; Bobadilla, G.; Bourque, D.; Bush, L.; Carandang, R.; Chiku, T.; Crosby, N.; De Seixas, M.; De Vries, J.; Doll, S.; Dufour, F.; Eckart, P.; Fahey, M.; Fenot, F.; Foeckersperger, S.; Fontaine, J.E.; Fowler, R.; Frey, H.; Fujio, H.; Gasa, J.M.; Gleave, J.; Godoe, J.; Green, I.; Haeberli, R.; Hanada, T.; Ha

1992-08-01

219

Nutrition in space  

NASA Technical Reports Server (NTRS)

The authors review studies conducted to define nutritional requirements for astronauts during space flight and to assess nutrition before, during, and after space flight. Topics include space food systems, research and limitations on spacecraft, physiological adaptation to weightlessness, energy requirements, dietary intake during space flight, bone demineralization, gastrointestinal function, blood volume, and nutrition requirements for space flight. Benefits of space-related nutrition research are highlighted.

Smith, S. M.; Davis-Street, J.; Rice, B. L.; Lane, H. W.

1997-01-01

220

The International Space Station in Space Exploration  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) Program has many lessons to offer for the future of space exploration. Among these lessons of the ISS Program, three stand out as instrumental for the next generation of explorers. These include: 1) resourcefulness and the value of a strong international partnership; 2) flexibility as illustrated by the evolution of the ISS Program and 3) designing with dissimilar redundancy and simplicity of sparing. These lessons graphically demonstrate that the ISS Program can serve as a test bed for future programs. As the ISS Program builds upon the strong foundation of previous space programs, it can provide insight into the prospects for continued growth and cooperation in space exploration. As the capacity for spacefaring increases worldwide and as more nations invest in space exploration and space sector development, the potential for advancement in space exploration is unlimited. By building on its engineering and research achievements and international cooperation, the ISS Program is inspiring tomorrow s explorers today.

Gerstenmaier, William H.; McKay, Meredith M.

2006-01-01

221

First results from the HST Grism Lens-Amplified Survey from Space (GLASS)  

NASA Astrophysics Data System (ADS)

GLASS is a cycle-21 large program with the Hubble Space Telescope, targeting 10 massive clusters, including the 6 Frontier Fields, using the WFC3 and ACS grisms. The program consists of 140 primary orbits and 140 parallel orbits. Using the clusters as cosmic telescopes, GLASS is taking spectra of faint background galaxies with unprecedented sensitivity and angular resolution. GLASS has 3 primary science drivers, although a variety of other science investigations are possible in combination with existing and planned imaging campaigns. The first key science goal is to shed light upon the role of galaxies in reionizing the universe, the topology of high redshift intergalactic/interstellar medium and Lyman alpha escape fraction. The second key science goal is to study gas accretion, star formation and outflows by mapping spatially resolved star formation and metallicity gradients in galaxies at z=1.3-2.3. The third key science goal is to study the environmental dependence of galaxy evolution, by mapping spatially resolved star formation in galaxies in the cluster cores and infalling regions. We present the details of the program and results from the first cluster observed by GLASS MACS0717.5+3745.

WANG, XIN; Schmidt, K. B.; Treu, T.; GLASS Team

2014-01-01

222

Spaced Retrieval: Absolute Spacing Enhances Learning Regardless of Relative Spacing  

ERIC Educational Resources Information Center

Repeated retrieval enhances long-term retention, and spaced repetition also enhances retention. A question with practical and theoretical significance is whether there are particular schedules of spaced retrieval (e.g., gradually expanding the interval between tests) that produce the best learning. In the present experiment, subjects studied and…

Karpicke, Jeffrey D.; Bauernschmidt, Althea

2011-01-01

223

Competing for shelf space  

Microsoft Academic Search

This paper studies competition for shelf space in a multi-supplier retail point. We consider a retailer that seeks to allocate her shelf space to maximize her profit. Because products associated with larger profit margin are granted more shelf space, suppliers can offer the retailer financial incentives to obtain larger space allocations. We analyze the competitive dynamics arising from the scarcity

Victor Martinez de Albeniz; Guillaume Roels

2007-01-01

224

Space: The New Frontier.  

ERIC Educational Resources Information Center

This document is designed primarily to describe the U.S. Space Program, its history, its current state of development, and its goals for the future. Chapter headings include: Space and You; The Early History of Space Flight; The Solar System; Space Probes and Satellites; Scientific Satellites and Sounding Rockets; Application Satellites, Unmanned…

National Aeronautics and Space Administration, Washington, DC.

225

Organic chemistry in space  

NASA Technical Reports Server (NTRS)

Organic cosmochemistry, organic materials in space exploration, and biochemistry of man in space are briefly surveyed. A model of Jupiter's atmosphere is considered, and the search for organic molecules in the solar system and in interstellar space is discussed. Materials and analytical techniques relevant to space exploration are indicated, and the blood and urine analyses performed on Skylab are described.

Johnson, R. D.

1977-01-01

226

Achievements in space robotics  

Microsoft Academic Search

Outer space is an ultimate field for the application of robotics technology. As outer space is a harsh environment with extreme temperatures, vacuum, radiation, gravity, and great distances, human access is very difficult and hazardous and is therefore limited. To assist human activities in space for constructing and maintaining space modules and structures, robotic manipulators have been playing essential roles

Kazuya Yoshida

2009-01-01

227

China's Space Policy  

Microsoft Academic Search

The scope of mankind's explorations has expanded from the land to the ocean, from the ocean to the air and from the air to outer space. Space technology, which emerged in the 1950's, opened up a new era of human exploration of outer space. Having developed rapidly for the last half century, mankind's activities in space have come a long

Y. Wen

2002-01-01

228

Minimum School Space Requirements.  

ERIC Educational Resources Information Center

This document presents methods for determining minimum school space requirements for Arizona public school classrooms; libraries and media centers; cafeterias; auditoriums and other multiuse space; science, art, vocational education, and physical education space; and non-educational areas. The space requirements are based on the following…

Arizona State School Facilities Board, Phoenix.

229

Overview and Recent Accomplishments of the Advanced Mirror Technology Development (AMTD) for Large Aperture UVOIR Space Telescopes Project  

NASA Technical Reports Server (NTRS)

Per Astro2010, a new, larger UVO telescope is needed to answer fundamental scientific questions, such as: is there life on Earth-like exoplanets; how galaxies assemble stellar populations; how baryonic matter interacts with intergalactic medium; and how solar systems form and evolve. And, present technology is not mature enough to affordably build and launch any potential UVO concept. Advanced Mirror Technology Development (AMTD) is a funded SAT project. Our objective is to mature to TRL-6 the critical technologies needed to produce 4-m or larger flight-qualified UVOIR mirrors by 2018 so that a viable mission can be considered by the 2020 Decadal Review. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND result in a high-performance low-cost low-risk system. To provide the science community with options, we are pursuing multiple technology paths. We have assembled an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes. One of our key accomplishments is that we have derived engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicle and its inherent mass and volume constraints. We defined and initiated a program to mature 6 key technologies required to fabricate monolithic and segmented space mirrors.

Stahl, H. Philip

2013-01-01

230

Space educators' handbook  

NASA Technical Reports Server (NTRS)

The Space Educators' Handbook is a collection of space exploration information available on Hypercard as a space education reference book. Ranging from early dreams of space ships to current manned missions, the more than four thousand cards include entries of statistics, historical facts and anecdotes, technical articles, accounts of NASA missions from Mercury through the space shuttle, biographical information on women and men who have contributed to space exploration, scientific facts, and various other space-related data. The means of presenting the data range from cartoons and drawings to lists and narratives, some briefly quoted and some reproduced in full.

Woodfill, Jerry

1992-01-01

231

The Space Shuttle  

NASA Technical Reports Server (NTRS)

As missions have become increasingly more challenging over the years, the most adaptable and capable element of space shuttle operations has proven time and again to be human beings. Human space flight provides unique aspects of observation. interaction and intervention that can reduce risk and improve mission success. No other launch vehicle - in development or in operation today - can match the space shuttle's human space flight capabilities. Preserving U.S. leadership in human space flight requires a strategy to meet those challenges. The ongoing development of next generation vehicles, along with upgrades to the space shuttle, is the most effective means for assuring our access to space.

Moffitt, William L.

2003-01-01

232

Bioprocessing in Space  

NASA Technical Reports Server (NTRS)

Proceedings are presented of the 1976 NASA Colloquium on bioprocessing in space. The program included general sessions and formal presentations on the following topics: NASA's Space Shuttle, Spacelab, and space-processing programs; the known unusual behavior of materials in space; space-processing experiment results; cell biology, gravity sensors in cells, space electrophoresis of living cells, new approaches to biosynthesis of biologicals from cell culture in space, and zero-g fermentation concepts; and upcoming flight opportunities and industrial application planning studies already underway.

Morrison, D. R. (compiler)

1977-01-01

233

Space Physiology and Operational Space Medicine  

NASA Technical Reports Server (NTRS)

The objectives of this slide presentation are to teach a level of familiarity with: the effects of short and long duration space flight on the human body, the major medical concerns regarding future long duration missions, the environmental issues that have potential medical impact on the crew, the role and capabilities of the Space Medicine Flight Surgeon and the environmental impacts experienced by the Apollo crews. The main physiological effects of space flight on the human body reviewed in this presentation are: space motion sickness (SMS), neurovestibular, cardiovascular, musculoskeletal, immune/hematopoietic system and behavioral/psycho-social. Some countermeasures are discussed to these effects.

Scheuring, Richard A.

2009-01-01

234

Space Shuttle Familiarization  

NASA Technical Reports Server (NTRS)

This slide presentation visualizes the NASA space center and research facility sites, as well as the geography, launching sites, launching pads, rocket launching, pre-flight activities, and space shuttle ground operations located at NASA Kennedy Space Center. Additionally, highlights the international involvement behind the International Space Station and the space station mobile servicing system. Extraterrestrial landings, surface habitats and habitation systems, outposts, extravehicular activity, and spacecraft rendezvous with the Earth return vehicle are also covered.

Mellett, Kevin

2006-01-01

235

Space Today Online  

NSDL National Science Digital Library

This online magazine is intended to provide accurate information on past, present, and future human activities in and about space, including space science, history, research, space flight, solar system exploration, deep space astronomy, and cosmology. It features news articles on space vehicles, astronauts, coming launches and landings, satellite missions, telescopes, and many other topics. The site also provides image galleries, videos, and resources for teachers such as lesson plans, book reviews, tutorials, and other items.

Curtis, Anthony R.

2006-03-07

236

Noncommutative spherically symmetric spaces  

SciTech Connect

We examine some noncommutative spherically symmetric spaces in three space dimensions. A generalization of Snyder's noncommutative (Euclidean) space allows the inclusion of the generator of dilations into the defining algebra of the coordinate and rotation operators. We then construct a spherically symmetric noncommutative Laplacian on this space having the correct limiting spectrum. This is presented via a creation and annihilation operator realization of the algebra, which may lend itself to a truncation of the Hilbert space.

Murray, Sean; Govaerts, Jan [Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium); Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium) and International Chair in Mathematical Physics and Applications, University of Abomey-Calavi, 072 B. P. 50, Cotonou (Benin)

2011-01-15

237

Ultrasymmetric Orlicz spaces  

NASA Astrophysics Data System (ADS)

It is proved that ultrasymmetric reflexive Orlicz spaces can be described exactly as all those Orlicz spaces which can be written as some Lorentz spaces. This description is an answer to the problem posed by Pustylnik in [E. Pustylnik, Ultrasymmetric spaces, J. London Math. Soc. (2) 68 (1) (2003) 165-182]. On the other hand, the Lorentz-Orlicz spaces with non-trivial indices of their fundamental functions are ultrasymmetric.

Astashkin, Sergei V.; Maligranda, Lech

2008-11-01

238

Affordable Space Tourism: SpaceStationSim.  

National Technical Information Service (NTIS)

For over 5 years, people have been living and working in space on the International Space Station (ISS), a state-of-the-art laboratory complex orbiting high above the Earth. Offering a large, sustained microgravity environment that cannot be duplicated on...

2006-01-01

239

Man in Space, Space in the Seventies.  

ERIC Educational Resources Information Center

Included is a summary of the Apollo lunar program to date. Projected future NASA programs planned for the 1970's are discussed under the headings Skylab, Space Shuttle, and Space Station. Possibilities for the 1980's are outlined in the final section. (Author/AL)

Froehlich, Walter

240

Commercial space launches  

NASA Astrophysics Data System (ADS)

While the space shuttle is expected to be the principle Space Transportation System (STS) of the United States, the Reagan Administration is moving ahead with the President's declared space policy of encouraging private sector operation of expendable launch vehicles (ELV's). With the signing of the “Commercial Space Launch Law” on October 30, the administration hopes that it has opened up the door for commercial ventures into space by streamlining regulations and coordinating applications for launches. The administration considers the development and operation of private sector ELV's as an important part of an overall U.S. space policy, complementing the space shuttle and government ELV's. The law follows by nearly a year the creation of the Office of Commercial Space Transportation at the U.S. Department of Transportation (DOT), which will coordinate applications for commercial space launches.

Robb, David W.

1984-04-01

241

Section 2: The Space of Media Space  

NASA Astrophysics Data System (ADS)

We began our study of media space with the social aspects of mediated communication because many in the computer-supported cooperative work (CSCW) realm are familiar with models, theories, frameworks, issues, and design approaches related to sociality. But the first media space research came from another set of traditions — the ordering of space and the making of place. Formally, these are the professional and intellectual provinces of architecture, which are probably remote from the disciplinary backgrounds of most readers. However, remoteness in terms of rhetoric and training does not prevent proximity to everyday human experience. The meaning of media space with respect to human experience is the focus of the articles in this section. The spaces are designed to have meaning, and the meaning of the design derives from spatial experience.

Harrison, Steve

242

Deep Space Communication  

NASA Technical Reports Server (NTRS)

ITU defines deep space as the volume of Space at distances from the Earth equal to, or greater than, 2 106 km. Deep Space Spacecraft have to travel tens of millions of km from Earth to reach the nearest object in deep space. Spacecraft mass and power are precious. Large ground-based antennas and very high power transmitters are needed to overcome large space loss and spacecraft's small antennas and low power transmitters. Navigation is complex and highly dependent on measurements from the Earth. Every deep space mission is unique and therefore very costly to develop.

Manshadi, Farzin

2012-01-01

243

Space Station Spartan study  

NASA Technical Reports Server (NTRS)

The required extension, enhancement, and upgrading of the present Spartan concept are described to conduct operations from the space station using the station's unique facilities and operational features. The space station Spartan (3S), the free flyer will be deployed from and returned to the space station and will conduct scientific missions of much longer duration than possible with the current Spartan. The potential benefits of a space station Spartan are enumerated. The objectives of the study are: (1) to develop a credible concept for a space station Spartan; and (2) to determine the associated requirements and interfaces with the space station to help ensure that the 3S can be properly accommodated.

Lane, J. H.; Schulman, J. R.; Neupert, W. M.

1985-01-01

244

New Dimension in Space Experimentation.  

National Technical Information Service (NTIS)

Space experimentation, cosmic origins, the long-term effects of the space environment on living things, the long-term effects of space environment on materials and hardware, seeds in space, power generation in space, experimentation with crystals, and the...

1983-01-01

245

Space transfer vehicles and space basing  

NASA Technical Reports Server (NTRS)

The topics covered include the following: (1) space basing agenda; (2) mission scenario 4E-5B, crew and Lunar Excursion Vehicle (LEV) delivery; (3) final concept candidate, crew concept 4E-2B; (4) space transfer vehicle (STV) concept 4E-5B; (5) configuration summary for crew concept 4E-5B; (6) configuration definition for crew concept 4E-5B; (7) low earth orbit node assembly and checkout operations; (8) criteria for operation objectives; (9) LTV and STV main engines; (10) Space Station Freedom impacts; (11) aerobrakes; and (12) on orbit operations. This document is presented in viewgraph form.

Kelley, Joe

1991-01-01

246

Open Space Plan.  

National Technical Information Service (NTIS)

The report defines urban open space, both publicly and privately owned. It sets forth objectives, policies and programs for the acquisition, preservation and use of open space for maximum benefit. It also contains an extensive standards and criteria secti...

1973-01-01

247

Prototype Space Fabrication Platform.  

National Technical Information Service (NTIS)

Current plans for constructing large structures in space entail fabricating the primary components, such as truss segments, on the ground and assembling them in space. This process requires an exorbitant number of support missions, and methods to minimize...

J. A. Bessel J. M. Ceney D. M. Crean E. A. Ingham D. J. Pabst

1993-01-01

248

Space station power system  

NASA Technical Reports Server (NTRS)

It is pointed out that space station planning at NASA began when NASA was created in 1958. However, the initiation of the program for a lunar landing delayed the implementation of plans for a space station. The utility of a space station was finally demonstrated with Skylab, which was launched in 1972. In May 1982, the Space Station Task Force was established to provide focus and direction for space station planning activities. The present paper provides a description of the planning activities, giving particular attention to the power system. The initial space station will be required to supply 75 kW of continuous electrical power, 60 kW for the customer and 15 kW for space station needs. Possible alternative energy sources for the space station include solar planar or concentrator arrays of either silicon or gallium arsenide.

Forestieri, A. F.; Baraona, C. R.

1984-01-01

249

Welding in Space Workshop  

NASA Technical Reports Server (NTRS)

The potential was discussed for welding in space, its advantages and disadvantages, and what type of programs can benefit from the capability. Review of the various presentations and comments made in the course of the workshop suggests several routes to obtaining a better understanding of how welding processes can be used in NASA's initiatives in space. They are as follows: (1) development of a document identifying well processes and equipment requirements applicable to space and lunar environments; (2) more demonstrations of welding particular hardware which are to be used in the above environments, especially for space repair operations; (3) increased awareness among contractors responsible for building space equipment as to the potential for welding operations in space and on other planetary bodies; and (4) continuation of space welding research projects is important to maintain awareness within NASA that welding in space is viable and beneficial.

Workman, Gary L.

1990-01-01

250

The Space Station Chronicles  

NASA Video Gallery

As early as the nineteenth century, writers and artists and scientists around the world began to publish their visions of a crewed outpost in space. Learn about the history of space stations, from ...

251

Space for Learning  

ERIC Educational Resources Information Center

Author feels that our understanding of educational space has not developed simultaneously with new concepts of the learning process. We must begin to think of using space in terms of user needs rather than in terms of curriculum divisions. (Editor)

Eriksen, Aase

1973-01-01

252

Space Station Freedom  

NASA Technical Reports Server (NTRS)

Information is given in viewgraph form on Space Station Freedom. Topics covered include future evolution, man-tended capability, permanently manned capability, standard payload rack dimensions, the Crystals by Vapor Transport Experiment (CVTE), commercial space projects interfaces, and pricing policy.

Keyes, Gilbert

1991-01-01

253

Dosimetry of space radiations  

NASA Technical Reports Server (NTRS)

Harmful effects of space radiation are discussed. Radiation dosimetry methods are given. Dosimetry monitoring is investigated. Methods for measuring space radiation by ionization, thermoluminescence, and nuclear photographic emulsions are described.

Arkhangelskiy, V. V.; Markelov, V. V.; Skvortsov, S. S.; Smirennyy, L. N.; Turkin, V. N.; Chernykh, I. V.

1973-01-01

254

Traveling Space Museum  

NASA Video Gallery

In an effort to inspire and motivate the next generation of space explorers, NASAâ??s Ames Research Center teamed up with the Traveling Space Museum to teach students the way astronauts are taughtâ...

255

Angry Birds Space Encounter  

NASA Video Gallery

At NASA's Kennedy Space Center Visitor Complex in Florida, a grand opening celebration was held for the new Angry Birds Space Encounter, March 22. Finland-based Rovio Entertainment, the creator of ...

256

Earth and Space  

NSDL National Science Digital Library

In earth and space science, students study the origin, structure, and physical phenomena of the earth and the universe. Earth and space science studies include concepts in geology, meteorology, oceanography, and astronomy.

K-12 Outreach,

257

Space Station Spartan Study.  

National Technical Information Service (NTIS)

The required extension, enhancement, and upgrading of the present Spartan concept are described to conduct operations from the space station using the station's unique facilities and operational features. The space station Spartan (3S), the free flyer wil...

J. H. Lane J. R. Schulman W. M. Neupert

1985-01-01

258

Space processing: A projection  

NASA Technical Reports Server (NTRS)

Estimates concerning space manufacturing, which might well become the largest and most specific application of space technology by the end of the century are given. Two classes of materials are considered - electronic crystals and biologicals.

Mccreight, L. R.; Griffin, R. N.

1972-01-01

259

Space Ship Pilot Lesson  

NSDL National Science Digital Library

The Space Ship Pilot lesson is a study of Newton's Laws of motion. Students use a model of a space shuttle and a ferry boat to study differences in an oject's motion with and without resistive forces.

Joiner, David; The Shodor Education Foundation, Inc.

260

Occupational Space Medicine  

NASA Technical Reports Server (NTRS)

Learning Objectives are: (1) Understand the unique work environment of astronauts. (2) Understand the effect microgravity has on human physiology (3) Understand how NASA Space Medicine Division is mitigating the health risks of space missions.

Tarver, William J.

2012-01-01

261

Space Studies Board, 1994  

NASA Technical Reports Server (NTRS)

This 1994 report of the Space Studies Board of the National Research Council summarizes the charter and organization of the board, activities and membership, major and short reports, and congressional testimony. A cumulative bibliography of the Space Studies (formerly Space Science) Board and its committees is provided. An appendix contains reports of the panel to review Earth Observing System Data and Information System (EOSDIS) plans. Major reports cover scientific opportunities in the human exploration of space, the dichotomy between funding and effectiveness in space physics, an integrated strategy for the planetary sciences for the years 1995-2010, and Office of Naval Research (ONR) research opportunities in upper atmospheric sciences. Short reports cover utilization of the space station, life and microgravity sciences and the space station program, Space Infrared Telescope Facility and the Stratospheric Observatory for Infrared Astronomy, and the Advanced X-ray Astrophysics Facility and Cassini Saturn Probe.

1995-01-01

262

Materials processing in space  

NASA Technical Reports Server (NTRS)

Prospects for materials processing in space are addressed. The types of materials that are of the most commercial interest in this regard are examined, and the relevant microgravity facilities and technologies are discussed. The characteristics of the Space Shuttle and the Free Flyer with regard to materials processing in space are briefly considered. The principal manufacturers and consumers of space-processed products are described. The potential impact of these products is assessed.

Kohli, Rajiv; Rancitelli, Louis A.

1987-01-01

263

VOIP over Space Networks  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews Voice over Internet Protocol (VOIP) over a space networking environment. The topics include: 1) Drivers for VOIP in Space; 2) Challenges in the Space Networking Environment: Long Latencies, Path errors, Simplex paths, Asymmetric paths, QoS requirements, Team-based operations, and Overhead concerns; 3) Possible VOIPOSN approaches; 4) Study of BER, code type and voice frame length on PESQ-MOS; 5) Codec Latency Trade Space; and 6) Testbed.

Okino, C.; Kwong, W.; Pang, Jackson; Gao, Jerry; Clare, L.

2006-01-01

264

Clinical Space Medicine Panel  

NASA Technical Reports Server (NTRS)

The practice of space medicine is diverse. It includes routine preventive medical care of astronauts and pilots, the development of inflight medical capability and training of flight crews as well as the preflight, inflight, and postflight medical assessment and monitoring. The Johnson Space Center Medical Operations Branch is a leader in the practice of space medicine. The papers presented in this panel will demonstrate some of the unique aspects of space medicine.

Baisden, Denise L.; Billica, Roger (Technical Monitor)

2000-01-01

265

Man's future in space  

NASA Technical Reports Server (NTRS)

Studies evaluating potential operational and commercial uses of space are being conducted, taking into account astronomy, astrophysics, manned bases and laboratories in earth orbit, space colonization, terrestrial communications, space processing and manufacturing, interstellar probes, planetary exploration, and the use of space for terrestrial energy supply. The present status in the exploration of the solar system is examined, giving attention to Jupiter, Venus, Mars, and Mercury. A brief outline of the development of human colonies on Mars is presented.

Freitag, R. F.

1975-01-01

266

US space commerce, 1991  

NASA Technical Reports Server (NTRS)

The topics are presented in viewgraph form and include the following: the US share of commercial payloads in comparison with Ariane's share; world communications satellite orders; the US share of prime contracts for construction of commercial communications satellites; emerging markets; space activities at the Commerce Department (DOC); Office of Space Commerce (OSC) mission description; key drivers for commercial space; and general DOC space policy themes.

Pace, Scott

1992-01-01

267

Space Shuttle Endeavour launch  

NASA Technical Reports Server (NTRS)

A smooth countdown culminated in a picture-perfect launch as the Space Shuttle Endeavour (STS-47) climbed skyward atop a ladder of billowing smoke. Primary payload for the plarned seven-day flight was Spacelab-J science laboratory. The second flight of Endeavour marks a number of historic firsts: the first space flight of an African-American woman, the first Japanese citizen to fly on a Space Shuttle, and the first married couple to fly in space.

1992-01-01

268

Space technology today  

NASA Technical Reports Server (NTRS)

The current status of major NASA programs and planning efforts is surveyed. Consideration is given to space-sciences programs (IRAS, SIRTF, Space Telescope, and planetary probes), applications programs (terrestrial remote sensing, communication, and meteorology), manned spacecraft, the STS, the Space Station, space commercialization efforts (materials processing and bioprocessing), and the feasibility of permanent lunar bases and manned Mars expeditions. Photographs and drawings are included.

Cohen, A.

1986-01-01

269

Animals in space  

NASA Technical Reports Server (NTRS)

Animals are indispensable to the space program. Their continued use could have many significant results. Those who are opposed to using animals in space should remember that space animals are treated humanely; they are necessary because results can be obtained from them that would be unobtainable from humans; and results from animal experiments can be applied to human systems. Therefore, NASA should continue to use animals in space research.

White, Angela

1988-01-01

270

Scale Space Hierarchy  

Microsoft Academic Search

We investigate the deep structure of a scale space image. We concentrate on scale space critical points— points with vanishing gradient with respect to both spatial and scale direction. We show that these points are always saddle points. They turn out to be extremely useful, since the iso-intensity manifolds through these points provide a scale space hierarchy tree and induce

Arjan Kuijper; Luc M. J. Florack; Max A. Viergever

2003-01-01

271

Deep space antennas  

Microsoft Academic Search

Three 26-m tracking antennas operated by the NASA Deep Space Network at Goldstone, Calif.; Madrid, Spain; and near Canberra, Australia, will cease operations on Dec. 1, 1981. The stations will continue to operate 64-m and 34-m deep space tracking antennas. Ending operation of the 26-m antennas will cause a reduction of about 30%; of the Deep Space Network tracking and

Peter M. Bell

1981-01-01

272

Economical space power systems  

NASA Astrophysics Data System (ADS)

A commercial approach to design and fabrication of an economical space power system is investigated. Cost projections are based on a 2 kW space power system conceptual design taking into consideration the capability for serviceability, constraints of operation in space, and commercial production engineering approaches. A breakdown of the system design, documentation, fabrication, and reliability and quality assurance estimated costs are detailed.

Burkholder, J. H.

1980-01-01

273

Hubble Space Telescope  

NSDL National Science Digital Library

This video segment from IdahoPTV's D4K describes the Hubble Space Telescope, shows visualizations of how optical and reflecting telescopes work, and shows original footage of the Hubble in Space. You hear why a telescope in space is valuable as well as see some of the amazing photographs the different cameras on the Hubble have taken.

Ptv, Idaho

2011-09-21

274

Views from Space  

Microsoft Academic Search

Only in the last century have human beings flown in space and men and machines have explored the worlds of our solar system. Robots have gone to most of the our neighboring worlds, the valleys of Mars and the clouds and moons of Jupiter. Instruments like the Hubble Space Telescope have looked into deep space. Those of us on the

Gary H. Kitmacher

2002-01-01

275

Management of outer space  

Microsoft Academic Search

Various aspects of space-environment management are discussed. Attention is called to the fact that, while space radio communications are already under an adequate management by the International Communications Union, the use of nuclear power sources is regulated by the recently adopted set of principles, and space debris will be discussed in the near future at the UN COPUOS, other aspects

Lubos Perek

1993-01-01

276

Space Station - early  

NASA Technical Reports Server (NTRS)

James Hansen wrote: 'Langley engineers check out the interior of the inflatable 24-foot space station in January 1962.'... 'The first idea for an inflatable station was the Erectable Torus Manned Space Laboratory. A Langley space station team led by Paul Hill and Emanuel 'Manny' Schnitzer developed the concept with the help of the Goodyear Aircraft Corporation.'

1962-01-01

277

Interpretation of space photolineaments  

Microsoft Academic Search

A definite pattern of space photolineaments exists, most have northeasterly and northwesterly strikes. The two main systems are traced in all platform regions. Seismic observations along regional profiles help in solving the fracture, the results of interpretation of space survey data should be compared with seismogeological sections along regional profiles. The comparisons show that space photolineaments coincide well with faults

L. N. Rozanov; I. N. Kalinina

1985-01-01

278

Space: A new frontier  

Microsoft Academic Search

The challenges and the promises of space colonization present an exciting opportunity for exploring and analyzing the values, the institutions and the physical environments we have created on Earth. Here we describe an interdisciplinary course, team-taught, that examines the current state of space exploration and the innovative technologies spawned by space research. The course also explores the possible social, economic,

Mona Cutolo; Denis M. Miranda

1986-01-01

279

Biotechnology in space laboratories  

Microsoft Academic Search

The advent of the Space Shuttle and of the Spacelab will open new perspectives to biotechnology in space. The objectives of this review are: a) to present an overview on the technological and scientific aspects of biological experiments performed on the past US and Soviet space missions, b) to describe the facilities offered by Spacelab in the future, c) to

Augusto Cogoli; Alex Tschopp

280

Space Jell-O  

NSDL National Science Digital Library

Albert Einstein proved that space bends around anything that has mass. This activity uses Jell-O's ability to bend around objects as a model for space bending around planets and stars. The more mass an object has, the more space (and Jell-O) bends around it. Learners can eat their model afterwards.

History, American M.

2012-06-26

281

Teacher in Space Project.  

ERIC Educational Resources Information Center

Prepared by NASA, this guide contains lessons dealing with space for use in elementary and secondary social studies classes. Activities are many and varied. For example, students analyze the costs and benefits of space travel, develop their own space station, and explore the decision-making processes involved in the shuttle. (RM)

Social Education, 1986

1986-01-01

282

Radars in space  

NASA Technical Reports Server (NTRS)

The capabilities of active microwave devices operating from space (typically, radar, scatterometers, interferometers, and altimeters) are discussed. General radar parameters and basic radar principles are explained. Applications of these parameters and principles are also explained. Trends in space radar technology, and where space radars and active microwave sensors in orbit are going are discussed.

Delnore, Victor E.

1990-01-01

283

Space and Imagination  

Microsoft Academic Search

Globalisation is affecting global space in various ways. One of its most dramatic effects is the creation of large spaces of exclusion. But also the privileged spaces ought to pay the cost of adjustment: they have to create a special image of themselves which differentiates them from other places, and in order to achieve a distinct image they have to

Anil K. Jain

2005-01-01

284

Space methods in oceanology  

NASA Technical Reports Server (NTRS)

The study of Earth from space with specialized satellites, and from manned orbiting stations, has become important in the space programs. The broad complex of methods used for probing Earth from space are different methods of the study of ocean, dynamics. The different methods of ocean observation are described.

Bolshakov, A. A.

1985-01-01

285

Pseudoneglect in Back Space  

ERIC Educational Resources Information Center

Successful interaction with the environment depends upon our ability to retain and update visuo-spatial information of both front and back egocentric space. Several studies have observed that healthy people tend to show a displacement of the egocentric frame of reference towards the left. However representation of space behind us (back space) has…

Cocchini, Gianna; Watling, Rosamond; Della Sala, Sergio; Jansari, Ashok

2007-01-01

286

The Ninth National Space Symposium  

NASA Astrophysics Data System (ADS)

Proceedings of the Ninth National Space Symposium held 13-16 April 1993 by the United States Space Foundation are presented. Presentations made at the symposium are included. Topics discussed include: Change, Challenge and Opportunity; Washington Insiders: National Space Policy and Budget Issues; Civil Space: a Vision for the Future; Space Power for an Expanded Vision; Unparalled Launch Vehicle Propulsion Capabilities; National Security Space Issues; Perspectives on the Air Force in Space; Future Technology: Space Propulsion, Earth Observation and International Cooperation; Achieving Efficient Space Transportation; the Future in Space Exploration; Kids, Parents and Teachers are into Space; and Public Congressional Forum on Space - International Space Issues.

Lipskin, Beth Ann; Patterson, Sara; Brescia, David A.; Burk, Donna; Flannery, Jack; St. John, Pat; Zimkas, Chuck

287

Space Simulation Facilities at IAL Space.  

National Technical Information Service (NTIS)

The thermal vacuum facilities of IAL SPACE were tailored for testing of the ESA payloads. They were progressively upgraded for cryogenic payloads including 4 K (liquid helium temperature) experiments. A detailed review of the three vacuum chambers, rangin...

M. Henrist A. Cucchiaro I. Domken J. P. Macau

1990-01-01

288

Space Science Using Columbus: Manned Space Science.  

National Technical Information Service (NTIS)

The scientific airlock of the Columbus attached pressurized module is described. Potential space science experiments and areas of research with the facility are suggested: wide field cameras; cosmic gamma ray burst detectors; total radiance measurement; a...

H. Olthof

1988-01-01

289

Space Engineering Technology (SET) Space Technology Institute  

NSDL National Science Digital Library

Prince George's Community College (PGCC) and the NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. PGCC, GSFC, and NASA's corporate contractors (GCA) have jointly designed the Space Engineering Technology degree curriculum (electronic systems) and two additional degree options: Computer Systems Technology (programming) and Quality Assurance Technology (quality science). Each degree option has a minimum requirement of 64 credit hours. Target Audience: 2-4 Year College Students, 2-4 Year College Faculty/Administrators

2009-10-23

290

Affordable Space Tourism: SpaceStationSim  

NASA Technical Reports Server (NTRS)

For over 5 years, people have been living and working in space on the International Space Station (ISS), a state-of-the-art laboratory complex orbiting high above the Earth. Offering a large, sustained microgravity environment that cannot be duplicated on Earth, the ISS furthers humankind s knowledge of science and how the body functions for extended periods of time in space all of which will prove vital on long-duration missions to Mars. On-orbit construction of the station began in November 1998, with the launch of the Russian Zarya Control Module, which provided battery power and fuel storage. This module was followed by additional components and supplies over the course of several months. In November 2000, the first ISS Expedition crew moved in. Since then, the ISS has continued to change and evolve. The space station is currently 240 feet wide, measured across the solar arrays, and 171 feet long, from the NASA Destiny Laboratory to the Russian Zvezda Habitation Module. It is 90 feet tall, and it weighs approximately 404,000 pounds. Crews inhabit a living space of about 15,000 cubic feet. To date, 90 scientific investigations have been conducted on the space station. New results from space station research, from basic science to exploration research, are being published each month, and more breakthroughs are likely to come. It is not all work on the space station, though. The orbiting home affords many of the comforts one finds on Earth. There is a weightless "weight room" and even a musical keyboard alongside research facilities. Holidays are observed, and with them, traditional foods such as turkey and cobbler are eaten, with lemonade to wash them down

2006-01-01

291

The Hubble Space Telescope Advanced Camera for Surveys Coma Cluster Survey. I. Survey Objectives and Design  

NASA Astrophysics Data System (ADS)

We describe the HST ACS Coma Cluster Treasury survey, a deep two-passband imaging survey of one of the nearest rich clusters of galaxies, the Coma Cluster (Abell 1656). The survey was designed to cover an area of 740 arcmin2 in regions of different density of both galaxies and intergalactic medium within the cluster. The ACS failure of 2007 January 27 leaves the survey 28% complete, with 21 ACS pointings (230 arcmin2) complete, and partial data for a further four pointings (44 arcmin2). The predicted survey depth for 10 ? detections for optimal photometry of point sources is g'=27.6 in the F475W filter and IC=26.8 mag in F814 (AB magnitudes). Initial simulations with artificially injected point sources show 90% recovered at magnitude limits of g'=27.55 and IC=26.65. For extended sources, the predicted 10 ? limits for a 1 arcsec2 region are g'=25.8 mag arcsec-2 and IC=25.0 mag arcsec-2. We highlight several motivating science goals of the survey, including study of the faint end of the cluster galaxy luminosity function, structural parameters of dwarf galaxies, stellar populations and their effect on colors and color gradients, evolution of morphological components in a dense environment, the nature of ultracompact dwarf galaxies, and globular cluster populations of cluster galaxies of a range of luminosities and types. This survey will also provide a local rich cluster benchmark for various well-known global scaling relations and explore new relations pertaining to the nuclear properties of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO10861.

Carter, David; Goudfrooij, Paul; Mobasher, Bahram; Ferguson, Henry C.; Puzia, Thomas H.; Aguerri, Alfonso L.; Balcells, Marc; Batcheldor, Dan; Bridges, Terry J.; Davies, Jonathan I.; Erwin, Peter; Graham, Alister W.; Guzmán, Rafael; Hammer, Derek; Hornschemeier, Ann; Hoyos, Carlos; Hudson, Michael J.; Huxor, Avon; Jogee, Shardha; Komiyama, Yutaka; Lotz, Jennifer; Lucey, John R.; Marzke, Ronald O.; Merritt, David; Miller, Bryan W.; Miller, Neal A.; Mouhcine, Mustapha; Okamura, Sadanori; Peletier, Reynier F.; Phillipps, Steven; Poggianti, Bianca M.; Sharples, Ray M.; Smith, Russell J.; Trentham, Neil; Tully, R. Brent; Valentijn, Edwin; Verdoes Kleijn, Gijs

2008-06-01

292

Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

An overview of the mission of the Hubble Space Telescope, a joint project between NASA and the European Space Agency which will be used to study deep space, as well as our solar system is presented. The video contains animations depicting the Hubble Space Telescope in orbit, as well as footage of scientists at the Space Telescope Science Institute making real time observations. The images Hubble acquires will be downloaded into a database that contains images of over 19,000,000 celestial objects called the Star Catalog.

1990-01-01

293

Space Acquired Photography  

USGS Publications Warehouse

Interested in a photograph of the first space walk by an American astronaut, or the first photograph from space of a solar eclipse? Or maybe your interest is in a specific geologic, oceanic, or meteorological phenomenon? The U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center is making photographs of the Earth taken from space available for search, download, and ordering. These photographs were taken by Gemini mission astronauts with handheld cameras or by the Large Format Camera that flew on space shuttle Challenger in October 1984. Space photographs are distributed by EROS only as high-resolution scanned or medium-resolution digital products.

Geological Survey (U.S.)

2008-01-01

294

The Space Science Group  

NSDL National Science Digital Library

The Space Science Group is part of the Division of Mathematics and Sciences at Northwestern State University in Natchitoches, La. The mission of The Space Science Group is to provide activities that encourage participation in math and science, build knowledge of basic concepts, teach basic science skill, and positively influence attitudes. The mission of The Space Science Group is to develop and implement programs which use aspects of the space program to motivate students to study mathematics and science. Many Space Science Group programs are described at the URL below.

1997-01-01

295

Storms in Space  

NASA Astrophysics Data System (ADS)

Introduction; The cast of characters; Vignettes of the storm; 1. Two kinds of weather; 2. The saga of the storm; 3. Weather stations in space; 4. Lights in the night: the signature of the storm; 5. A walking tour of the magnetosphere; 6. The sun: where it all begins; 7. Nowcasting and forecasting storms in space; 8. Technology and the risks from storms in space; 9. A conversation with Joe Allen; 10. Manned exploration and space weather hazards; 11. The present and future of space weather forecasting; Mathematical appendix. A closer look; Glossary; Figure captions.

Freeman, John W.

2012-11-01

296

TANK SPACE OPTIONS REPORT  

SciTech Connect

Since this report was originally issued in 2001, several options proposed for increasing double-shell tank (DST) storage space were implemented or are in the process of implementation. Changes to the single-shell tank (SST) waste retrieval schedule, completion of DST space saving options, and the DST space saving options in progress have delayed the projected shortfall of DST storage space from the 2007-2011 to the 2018-2025 timeframe (ORP-11242, River Protection Project System Plan). This report reevaluates options from Rev. 0 and includes evaluations of new options for alleviating projected restrictions on SST waste retrieval beginning in 2018 because of the lack of DST storage space.

WILLIS WL; AHRENDT MR

2009-08-11

297

Space colony transportation  

NASA Technical Reports Server (NTRS)

The Space Shuttle, Space Tug, and Spacelab are described as the basic transport vehicles for space exploration and operations in the coming decade, and some future space vehicle developments are anticipated. Components of Shuttle (Orbiter, external hydrogen-oxygen propellant tanks, solid boosters), basic maneuvers, and missions are described briefly. Expendable and reusable variants of the Interim Upper Stage (Space Tug) and Spacelab missions are described briefly. A future Large Lift Vehicle recoverable booster and an expendable chemical-nuclear system for the turn of the century are sketched.

Wilson, R.

1977-01-01

298

Center for Space Construction  

NASA Technical Reports Server (NTRS)

The Center for Space Construction (CSC) at University of Colorado at Boulder is one of eight University Space Engineering Research Centers established by NASA in 1988. The mission of the Center is to conduct research into space technology and to directly contribute to space engineering education. The Center reports to the Department of Aerospace Engineering Sciences and resides in the College of Engineering and Applied Sciences. The College has a long and successful track record of cultivating multi-disciplinary research and education programs. The Center for Space Construction represents prominent evidence of this record. The basic concept on which the Center was founded is the in-space construction of large space systems, such as space stations, interplanetary space vehicles, and extraterrestrial space structures. Since 1993, the scope of CSC research has evolved to include the design and construction of all spacecraft, large and small. With the broadened scope our research projects seek to impact the technological basis for spacecraft such as remote sensing satellites, communication satellites and other special-purpose spacecraft, as well as large space platforms. A summary of accomplishments, including student participation and degrees awarded, during the contract period is presented.

Su, Renjeng

1998-01-01

299

Space Suit Thermal Dynamics  

NASA Technical Reports Server (NTRS)

The present NASA space suit (the Shuttle EMU) is a self-contained environmental control system, providing life support, environmental protection, earth-like mobility, and communications. This study considers the thermal dynamics of the space suit as they relate to astronaut thermal comfort control. A detailed dynamic lumped capacitance thermal model of the present space suit is used to analyze the thermal dynamics of the suit with observations verified using experimental and flight data. Prior to using the model to define performance characteristics and limitations for the space suit, the model is first evaluated and improved. This evaluation includes determining the effect of various model parameters on model performance and quantifying various temperature prediction errors in terms of heat transfer and heat storage. The observations from this study are being utilized in two future design efforts, automatic thermal comfort control design for the present space suit and design of future space suit systems for Space Station, Lunar, and Martian missions.

Campbell, Anthony B.; Nair, Satish S.; Miles, John B.; Iovine, John V.; Lin, Chin H.

1998-01-01

300

RBSP Space Weather data  

NASA Astrophysics Data System (ADS)

On August 23, 2012, NASA will launch two identical probes into the radiation belts to provide unprecedented insight into the physical processes and dynamics of near-Earth space. The RBSP mission in addition to the scientific data return, provides a 1Kbps real-time space weather broadcast data in support of real time space weather modeling, forecast and prediction efforts. Networks of ground stations have been identified to downlink the space weather data. The RBSP instrument suites have selected space weather data to be broadcast from their collected space data on board the spacecraft, a subset from measurements based on information normally available to the instrument. The data subset includes particle fluxes at a variety of energies, and magnetic and electric field data. This selected space weather data is broadcast at all times through the primary spacecraft science downlink antennas when an observatory is not in a primary mission-related ground contact. The collected data will resolve important scientific issues and help researchers develop and improve various models for the radiation belts that can be used by forecasters to predict space weather phenomena and alert astronauts and spacecraft operators to potential hazards. The near real-time data from RBSP will be available to monitor and analyze current environmental conditions, forecast natural environmental changes and support anomaly resolution. The space weather data will be available on the RBSP Science Gateway at http://athena.jhuapl.edu/ and will provide access to the space weather data received from the RBSP real-time space weather broadcast. The near real-time data will be calibrated and displayed on the web as soon as possible. The CCMC will ingest the RBSP space weather data into real-time models. The raw space weather data will be permanently archived at APL. This presentation will provide a first look at RBSP space weather data products.

Weiss, M.; Fox, N. J.; Mauk, B. H.; Barnes, R. J.; Potter, M.; Romeo, G.; Smith, D.

2012-12-01

301

Smoking spaces as enabling spaces of wellbeing.  

PubMed

A persistent emphasis on the negative biomedical effects of cigarette smoking effectively glosses over the affectual-sensual and social wellbeing that smoking can enable. In addition, while tobacco research has recently been more attuned to the stigmatizing affects brought about by smoking de-normalization efforts, a lot less attention has been placed on how smokers negotiate these feelings of stigmatization so as to restore their personal spaces of wellbeing. In this paper, I situate my investigation of smoking geographies in the burgeoning literature on enabling spaces which focuses on how places co-constitute our ability to act/affect in empowering ways. By deploying qualitative research methods such as in-depth interviews, I argue that an acknowledgment of how smoking spaces in Singapore can be enabling along affectual, sensorial and social registers is long overdue. While it is not my purpose to systematically downplay the damaging health effects that smoking can engender, a focus on enabling smoking spaces emphasizes the role of smokers as creative agents capable of (re)fashioning their own holistic and subjective versions of wellbeing. In so doing, I hope to contribute to the existing research on smoking spaces and a recent profusion of work on relational geographies of affect. PMID:24121560

Tan, Qian Hui

2013-11-01

302

Space science overview  

NASA Astrophysics Data System (ADS)

The Space Science Program of the Canadian Space Agency has the objective of ensuring that Canada maintains a position of excellence in the worldwide scientific exploration of space. The program provides opportunities for Canadian scientists and engineers to participate in quality national and international space projects in the disciplines of space physics, atmospheric chemistry, astronomy and life, and materials sciences in microgravity. Another objective of the program is to enhance Canadian industrial capabilities in space technology. The history of space science research in Canada is reviewed, from the early ground-based and balloon or rocket observations of northern latitude phenomena, to the development of the Alouette satellite and international cooperative programs. The structure of the Canadian Space Agency and its committees is outlined along with the process used for selecting research projects. The lack of Canadian launch capability has strongly driven Canada to international collaboration in which launch costs are shared. Canada is presently participating in eight programs which utilize free-flying satellites and which include Canadian contribution of space-qualified hardware in exchange for the data generated by the satellites. Collaboration with NASA occurs in shuttle projects and in the multinational Space Station Freedom.

Wetter, Barry L.

303

CONSTRAINING DUST AND COLOR VARIATIONS OF HIGH-z SNe USING NICMOS ON THE HUBBLE SPACE TELESCOPE  

SciTech Connect

We present data from the Supernova Cosmology Project for five high redshift Type Ia supernovae (SNe Ia) that were obtained using the NICMOS infrared camera on the Hubble Space Telescope. We add two SNe from this sample to a rest-frame I-band Hubble diagram, doubling the number of high redshift supernovae on this diagram. This I-band Hubble diagram is consistent with a flat universe ({omega}{sub M}, {omega}{sub {lambda}}) = (0.29, 0.71). A homogeneous distribution of large grain dust in the intergalactic medium (replenishing dust) is incompatible with the data and is excluded at the 5{sigma} confidence level, if the SN host galaxy reddening is corrected assuming R{sub V} = 1.75. We use both optical and infrared observations to compare photometric properties of distant SNe Ia with those of nearby objects. We find generally good agreement with the expected color evolution for all SNe except the highest redshift SN in our sample (SN 1997ek at z = 0.863) which shows a peculiar color behavior. We also present spectra obtained from ground-based telescopes for type identification and determination of redshift.

Nobili, S.; Amanullah, R.; Goobar, A. [Department of Physics, Stockholm University, Albanova University Center, S-106 91 Stockholm (Sweden)] (and others)

2009-08-01

304

Science in space with the Space Station  

NASA Technical Reports Server (NTRS)

The potential of the Space Station as a versatile scientific laboratory is discussed, reviewing plans under consideration by the NASA Task Force on Scientific Uses of the Space Station. The special advantages offered by the Station for expanding the scope of 'space science' beyond astrophysics, geophysics, and terrestrial remote sensing are stressed. Topics examined include the advantages of a manned presence, the scientific value and cost effectiveness of smaller, more quickly performable experiments, improved communications for ground control of Station experiments, the international nature of the Station, the need for more scientist astronauts for the Station crew, Station on-orbit maintenance and repair services for coorbiting platforms, and the need for Shuttle testing of proposed Station laboratory equipment and procedures.

Banks, Peter M.

1987-01-01

305

The International Space University  

NASA Technical Reports Server (NTRS)

The International Space University (ISU) was founded on the premise that any major space program in the future would require international cooperation as a necessary first step toward its successful completion. ISU is devoted to being a leading center for educating future authorities in the world space industry. ISU's background, goals, current form, and future plans are described. The results and benefits of the type of education and experience gained from ISU include technical reports describing the design projects undertaken by the students, an exposure to the many different disciplines which are a part of a large space project, an awareness of the existing activities from around the world in the space community, and an international professional network which spans all aspects of space activities and covers the globe.

Davidian, Kenneth J.

1990-01-01

306

Space resources. Overview  

NASA Technical Reports Server (NTRS)

Space resources must be used to support life on the Moon and in the exploration of Mars. Just as the pioneers applied the tools they brought with them to resources they found along the way rather than trying to haul all their needs over a long supply line, so too must space travelers apply their high technology tools to local resources. This overview describes the findings of a study on the use of space resources in the development of future space activities and defines the necessary research and development that must precede the practical utilization of these resources. Space resources considered included lunar soil, oxygen derived from lunar soil, material retrieved from near-Earth asteroids, abundant sunlight, low gravity, and high vacuum. The study participants analyzed the direct use of these resources, the potential demand for products from them, the techniques for retrieving and processing space resources, the necessary infrastructure, and the economic tradeoffs.

Mckay, Mary Fae (editor); Mckay, David S. (editor); Duke, Michael B. (editor)

1992-01-01

307

Ultrasound in space  

NASA Technical Reports Server (NTRS)

Physiology of the human body in space has been a major concern for space-faring nations since the beginning of the space era. Ultrasound (US) is one of the most cost effective and versatile forms of medical imaging. As such, its use in characterizing microgravity-induced changes in physiology is being realized. In addition to the use of US in related ground-based studies, equipment has also been modified to fly in space. This involves alteration to handle the stresses of launch and different power and cooling requirements. Study protocols also have been altered to accommodate the microgravity environment. Ultrasound studies to date have shown a pattern of adaptation to microgravity that includes changes in cardiac chamber sizes and vertebral spacing. Ultrasound has been and will continue to be an important component in the investigation of physiological and, possibly, pathologic changes occurring in space or as a result of spaceflight.

Martin, David S.; South, Donna A.; Garcia, Kathleen M.; Arbeille, Philippe

2003-01-01

308

Gymnastics in Phase Space  

SciTech Connect

As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

Chao, Alexander Wu; /SLAC

2012-03-01

309

Space biology research development  

NASA Technical Reports Server (NTRS)

The purpose of the Search for Extraterrestrial Intelligence (SETI) Institute is to conduct and promote research related activities regarding the search for extraterrestrial life, particularly intelligent life. Such research encompasses the broad discipline of 'Life in the Universe', including all scientific and technological aspects of astronomy and the planetary sciences, chemical evolution, the origin of life, biological evolution, and cultural evolution. The primary purpose was to provide funding for the Principal Investigator to collaborate with the personnel of the SETI Institute and the NASA-Ames Research center in order to plan and develop space biology research on and in connection with Space Station Freedom; to promote cooperation with the international partners in the space station; to conduct a study on the use of biosensors in space biology research and life support system operation; and to promote space biology research through the initiation of an annual publication 'Advances in Space Biology and Medicine'.

Bonting, Sjoerd L.

1993-01-01

310

Space Activities of Western Europe.  

National Technical Information Service (NTIS)

This paper illustrates the diversity of European space activity and shows how the various national space projects, as well as the joint programs administered by the European Space Agency, have evolved since Europe's entry into the space age. Detailed desc...

A. V. Harriott

1986-01-01

311

Space Station galley design  

NASA Technical Reports Server (NTRS)

An Advanced Food Hardware System galley for the initial operating capability (IOC) Space Station is discussed. Space Station will employ food hardware items that have never been flown in space, such as a dishwasher, microwave oven, blender/mixer, bulk food and beverage dispensers, automated food inventory management, a trash compactor, and an advanced technology refrigerator/freezer. These new technologies and designs are described and the trades, design, development, and testing associated with each are summarized.

Trabanino, Rudy; Murphy, George L.; Yakut, M. M.

1986-01-01

312

International Space Station exhibit  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) exhibit in StenniSphere at John C. Stennis Space Center in Hancock County, Miss., gives visitors an up-close look at the largest international peacetime project in history. Step inside a module of the ISS and glimpse how astronauts will live and work in space. Currently, 16 countries contribute resources and hardware to the ISS. When complete, the orbiting research facility will be larger than a football field.

2000-01-01

313

Space Weather: Welcome, SEC  

NSDL National Science Digital Library

This video presentation welcomes the Space Environment Center (SEC) to the National Weather Service (NWS) as an operational entity of the National Centers for Environmental Prediction (NCEP) family. Describing the ways in which space weather affects global communications and power resources, it demonstrates the importance of space weather forecasting as a part of the NWS family of services. With the inclusion of SEC, the NWS now provides environmental understanding from the sun to the sea.

Spangler, Tim

2005-01-11

314

Space program in Taiwan  

Microsoft Academic Search

The National Space Program Office (NSPO) was established in 1991 to execute the space program in Taiwan. The first fifteen-year space program (1991-2006) consists of setting up infrastructure and carrying out three satellite programs (ROCSAT-1, ROCSAT-2 and ROCSAT-3). For the second fifteen-year program (2004-2018), NSPO will execute five major missions that include remote sensing satellites, broadband communication satellite, micro-satellites, international

L.-C. Lee

2004-01-01

315

Advanced space transportation systems  

NASA Technical Reports Server (NTRS)

Information is given in viewgraph form relative to the advanced space transportation systems of the Space Station Freedom. Topics covered include heavy lift launch vehicle needs, requirements, and options; future launch vehicle concepts; modifications to the external tank; the Cargo Transfer Vehicle concept; lunar transportation options, Mars transportation options; the Assured Crew Return Vehicle (ACRV) baseline concept; Space Exploration Initiative (SEI) nodes options; and committee recommendations.

Davies, Robert J.

1991-01-01

316

Rocket and Space Technology  

NSDL National Science Digital Library

This site, created by author Robert Braeuning, features material on orbital mechanics, propulsion, rocket hardware, space centers and missions. It includes definitions of important terms and black-and-white diagrams. The page also features information on rocket propellants, rocket propulsion, orbital mechanics, spacecraft systems, vehicle specifications, launch vehicles, manned space flights, planetary spacecraft, and lunar spacecraft. A glossary and discussion forum are also provided. This is a nice resource for a overview of all things involving rockets or other space technologies.

Braeuning, Robert

2009-05-04

317

Space transportation briefings  

Microsoft Academic Search

The National Aeronautics and Space Administration (NASA) began a comprehensive series of media briefings on the development and utilization of the nation's space transportation system September 10 at NASA headquarters in Washington, D.C. The series will continue throughout the initial flight testing of Columbia, the first space shuttle in the United States fleet of new Earth-orbiting vehicles.During the first briefing

Peter M. Bell

1980-01-01

318

news.space  

NSDL National Science Digital Library

From Science Matters, a company aiming to increase scientific knowledge of every individual, news.space is a gathering of information on current space topics. General knowledge categories include spacecraft, mars, space, and solar; content in each category, most of which consists of hyperlinks to other sites, ranges from news releases to high quality photo images to background information on relevant topics. Chat and Multimedia sections give users the opportunity to visit chat sites, view videos, and listen to recordings.

319

THz Sources for Space  

NASA Technical Reports Server (NTRS)

Terahertz is the primary frequency for line and continuum radiation from cool (5-100K) gas (atoms and molecules) and dust. This viewgraph presentation reviews the reasons for the interest in Terahertz Space Applications; the Terahertz Space Missions: in the past, present and planned for the future, Terahertz source requirements and examples of some JPL instruments; and a case study for a flight deliverable: THz Local Oscillators for ESA s Herschel Space Telescope

Siegel, Peter H.; Ward, John; Maiwald, Frank; Mehdi, Imran

2007-01-01

320

The Space Elevator  

NASA Astrophysics Data System (ADS)

The Space Elevator is conceived to be a carbon nanotube ribbon stretching from an Earth station in the ocean on the equator to far beyond geosynchronous altitude. This elevator co-rotates with the Earth. Climbers ascend the ribbon using power beamed from Earth to launch spacecraft in orbit or to other worlds. The requirements of the ribbon material, challenges to the building of the space elevator, deployment and the promise of the space elevator are briefly discussed in this paper.

Laubscher, Bryan E.

2005-09-01

321

Space Math - I  

NSDL National Science Digital Library

This is a booklet containing 20 problem sets that involve a variety of math skills, including equations and substitution, time calculations, reading, algebra, and more. Each set of problems is contained on one page. Learners will use mathematics to explore space science topics related to our Sun, auroras, solar features, space weather, sunspots, and solar storms. This booklet can be found on the Space Math@NASA website.

322

Space Station - early  

NASA Technical Reports Server (NTRS)

Manned Space Laboratory Research. James Hansen wrote: 'Testing indicated that the inflatable torus could be packaged around the hub so that it occupied only 2 percent of its inflated volume.' 'The first idea for an inflatable station was the Erectable Torus Manned Space Laboratory. A Langley space station team led by Paul Hill and Emanuel 'Manny' Schnitzer developed the concept with the help of the Goodyear Aircraft Corporation.'

1961-01-01

323

SSC Space Physics Tutorial  

NSDL National Science Digital Library

Provided by the Space Physics Center of the UCLA Institute of Geophysics and Planetary Physics, the Space Physics Tutorial gives advanced high school and college students an introduction to Space Physics. Topics include the magnetosphere, magnetopause, the Pioneer Venus Mission, planetary magnetospheres, and more. Two downloadable papers are also available in Adobe Acrobat (.pdf) format entitled: Solar Wind and Interplanetary Magnetic Field: A Tutorial and The Solar Wind Interaction with the Earth's Magnetosphere: A Tutorial.

2000-01-01

324

Lyophilization process design space.  

PubMed

The application of key elements of quality by design (QbD), such as risk assessment, process analytical technology, and design space, is discussed widely as it relates to freeze-drying process design and development. However, this commentary focuses on constructing the Design and Control Space, particularly for the primary drying step of the freeze-drying process. Also, practical applications and considerations of claiming a process Design Space under the QbD paradigm have been discussed. PMID:23946165

Patel, Sajal Manubhai; Pikal, Michael J

2013-11-01

325

Basics of Space Flight  

NSDL National Science Digital Library

This training module was designed to help the user identify and grasp basic concepts associated with space travel and deep space missions. Separate sections deal with topics such as the physical environment of space (solar system, gravity, orbital mechanics), flight projects (mission concepts, system requirements, design, onboard systems and instruments), and flight operations (launch, cruise, encounter). Links to related topics are embedded in the text.

326

Space construction data base  

NASA Technical Reports Server (NTRS)

Construction of large systems in space is a technology requiring the development of construction methods to deploy, assemble, and fabricate the elements comprising such systems. A construction method is comprised of all essential functions and operations and related support equipment necessary to accomplish a specific construction task in a particular way. The data base objective is to provide to the designers of large space systems a compendium of the various space construction methods which could have application to their projects.

1979-01-01

327

Space Group Symmetry  

NSDL National Science Digital Library

In this problem set, students are given space group symmetry diagrams for primitive (P) orthorhombic space groups. For each diagram they must write down the symmetry axis (either 2 or 21) that is parallel to each major axis, and give the symmetry plane (a, b, c, n, or m) that is normal (perpendicular)to each. They must also give the simplified Hermann-Mauguin symbol for the space group.

328

Space Odyssey Gift Shop  

NASA Technical Reports Server (NTRS)

The Space Odyssey Gift Shop located in StenniSphere at the John C. Stennis Space Center in Hancock County, Miss., offers every visitor the opportunity to go home with 'the right stuff' from his or her StenniSphere visit. The gift shop is located just inside the front doors to StenniSphere and offers a wide range of space-related apparel, memorabilia, toys, books, mission patches and more.

2000-01-01

329

Military space assets  

Microsoft Academic Search

\\u000a The concept of a space weapon has its origins in the works of space visionary, Hermann Oberth. Oberth’s publication, Die Rakete zu den Planetenraümen (The Rockets into Interplanetary Space), mentioned reconnaissance from orbit and suggested the idea of a giant mirror, 100 km in diameter, which could be used to\\u000a set enemy ammunition dumps on fire! However, while Oberth may

Erik Seedhouse

330

Whippo Problem Space  

NSDL National Science Digital Library

This problem space provides resources for going beyond the discussions of whale evolution presented in biology textbooks to look at how different types of data can be used to resolve this set of phylogenetic puzzles and to explore other related questions. In addition to providing some background on this topic the problem space has: * rich data resources for examining evolutionary relationships * curricular materials focusing on tree reading and interpretation * some suggestions for ways to extend this problem space with related research projects

Sam Donovan (University of Pittsburgh;Department of Learning and Instruction)

2005-12-17

331

Space Mechanisms Technology Workshop  

NASA Technical Reports Server (NTRS)

The Mechanical Components Branch at NASA Glenn Research Center hosted a workshop to discuss the state of drive systems technology needed for space exploration. The Workshop was held Thursday, November 2, 2000. About 70 space mechanisms experts shared their experiences from working in this field and considered technology development that will be needed to support future space exploration in the next 10 to 30 years.

Oswald, Fred B. (Editor)

2001-01-01

332

Kennedy Space Center  

NASA Technical Reports Server (NTRS)

Among 2011's many accomplishments, we safely retired the Space Shuttle Program after 30 incredible years; completed the International Space Station and are taking steps to enable it to reach its full potential as a multi-purpose laboratory; and helped to expand scientific knowledge with missions like Aquarius, GRAIL, and the Mars Science Laboratory. Responding to national budget challenges, we are prioritizing critical capabilities and divesting ourselves of assets no longer needed for NASA's future exploration programs. Since these facilities do not have to be maintained or demolished, the government saves money. At the same time, our commercial partners save money because they do not have to build new facilities. It is a win-win for everyone. Moving forward, 2012 will be even more historically significant as we celebrate the 50th Anniversary of Kennedy Space Center. In the coming year, KSC will facilitate commercial transportation to low-Earth orbit and support the evolution of the Space Launch System and Orion crew vehicle as they ready for exploration missions, which will shape how human beings view the universe. While NASA's Vision is to lead scientific and technological advances in aeronautics and space for a Nation on the frontier of discovery KSC's vision is to be the world's preeminent launch complex for government and commercial space access, enabling the world to explore and work in space. KSC's Mission is to safely manage, develop, integrate, and sustain space systems through partnerships that enable innovative, diverse access to space and inspires the Nation's future explorers.

Griffin, Amanda

2012-01-01

333

Space Exploration Initiative  

NASA Technical Reports Server (NTRS)

An overview of President Bush's Space Exploration Initiative (SEI) and it's three main components, Space Station Freedom, a Permanent Lunar Base, and a Manned Mission to Mars is provided. Computer simulations of the Space Station Freedom and Permanent Lunar Base are shown, and an animated sequence describes a Mars mission where heavy lift vehicle will bring components of a Mars Spacecraft into orbit, where it will be put together by astronauts using a robotic arm. The Mars spacecraft is shown orbiting Mars and discharging a lander to the surface, carrying human explorers. The video also details the SEI's Outreach Program, designed to garner interest in and ideas for Space Exploration.

1990-01-01

334

Man in space.  

PubMed

Today, more than 20 years after the first in the world man's space walk, soviet cosmonautics gained large experience of extravehicular activity (EVA). Space suits of high reliability, onboard facilities for passing through the airlock, sets of special tools and technological rigging, as well as procedures for carrying out various EVA's were developed. In the course of the Salyut-7 space station orbital operation the EVA's have become regular. The author of the report as the participant of the EVA's considers the main steps of man activities in space and analyzes specific problems arised in performing such activities. PMID:11542958

Solovjev, V A

1987-09-01

335

Adventures in Space Medicine  

NASA Technical Reports Server (NTRS)

Human space flight experience has demonstrated a variety of hazards and risks to health and performance. In developing ways to help respond to these issues, the field of space medicine has developed a comprehensive program of space flight health risk management that has resulted in positive contributions to medicine and society in general. Examples include accelerated focus on critical health issues such as aging and osteoporosis, and development of new technologies such as non-invasive diagnostic testing for diabetics. The role of health care professionals in human space exploration represents a fulfillment of new adventures and expanding frontiers.

Billica, Roger D.

1999-01-01

336

National Space Society  

NSDL National Science Digital Library

The National Space Society (NSS) is a nonprofit organization dedicated to the creation of a spacefaring civilization. The NSS web site features information about the organization, its mission and vision, membership information, and a listing of NSS local chapters. The library features links to videos, books, and other publications on space settlements and bases, space policy, and technology. There is also information on the organization's magazine, "Ad Astra," including instructions for authors, publishing and advertising guidelines, and some archived content. Other materials include news articles, event announcements, and information on current space missions.

2005-02-01

337

History of Space Exploration  

NSDL National Science Digital Library

Users can choose from an extensive selection of links to resources for use in the study of the history of space exploration. The links provide access to historic information and publications, chronologies, and mission summaries for American, Russian, European, and other space missions. For educators, there are links to guides to robotic spacecraft and to observing the space shuttle in orbit. Links are also provided to a variety of spacecraft homepages and to other topics such as a primer on the basics of space flight, the Apollo lunar surface journals, and the NASA historic archives.

338

Start of space tourism  

NASA Astrophysics Data System (ADS)

Space tourism means commercialization of manned space flight. From the early stage of space development, space commercialization is a profound theme in multidisciplinary fields, on the basis of a principle that the outcomes of advanced technique developed by tax should be returned to citizens. In these days, space satellite system in which users pay a fee for utilization has succeeded commercially in business such as communication network or broadcasting, and an attempt has been made to observe the earth from outer space to resolve global problems, such as environmental destruction. There is also an increasing interest in space tourism, however, many obstacles should be overcome for the realization, especially the medical problems such as effect of acceleration, cosmic ray, noise or weightless condition. In addition, the space flight business should be managed on the commercial base so that reasonable cost and large number of passengers are essential. It is necessary to design rockets suitable for tourism. For attractive design, the policy of space tourism should be clarified.

Nagatomo, Makoto

1993-03-01

339

The deep space network  

NASA Technical Reports Server (NTRS)

Summaries are given of Deep Space Network progress in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations.

1975-01-01

340

International Space Station: Update  

NSDL National Science Digital Library

In November 1998, Zarya was launched into space, ushering in the era of the International Space Station (featured in the November 25, 1998 Scout Report for Science & Engineering). This month, the docking of the Zvezda Service Module marks the beginning of yet another phase -- in which Zvezda will serve as living quarters to the first ever resident crew (Expedition One), scheduled to arrive at the International Space Station in early November. This site from NASA provides updated information on the International Space Station, including recent news, planned missions, and a virtual tour of the (yet-to-be-completed) station.

341

Space Station - early  

NASA Technical Reports Server (NTRS)

Manned Space Laboratory Research. James Hansen wrote: 'Langley built and tested various models of the Erectable Torus Manned Space Laboratory, including a full-scale research model constructed by Goodyear.' The uninflated station was packed around a 24-foot diameter torus and could be launched inside a rocket. 'The first idea for an inflatable station was the Erectable Torus Manned Space Laboratory. A Langley space station team led by Paul Hill and Emanuel 'Manny' Schnitzer developed the concept with the help of the Goodyear Aircraft Corporation.'

1961-01-01

342

Space Jell-O  

NSDL National Science Digital Library

This hands-on OLogy experiment uses Jell-O, fruit, nuts, and candy to demonstrate how space bends around anything that has mass. The activity begins with kid-friendly introductions to the concept of mass and Einstein's theory of bending space. The illustrated, step-by-step directions include notes about how the fruit, nuts, and candy represent stars, planets, and other objects in space. At the end, kids are encouraged to celebrate their new-found knowledge by digging into their edible space.

343

Space construction activities  

NASA Technical Reports Server (NTRS)

The Center for Space Construction at the University of Colorado at Boulder was established in 1988 as a University Space Engineering Research Center. The mission of the Center is to conduct interdisciplinary engineering research which is critical to the construction of future space structures and systems and to educate students who will have the vision and technical skills to successfully lead future space construction activities. The research activities are currently organized around two central projects: Orbital Construction and Lunar Construction. Summaries of the research projects are included.

1991-01-01

344

Space industrialization opportunities  

NASA Technical Reports Server (NTRS)

The current status of efforts to develop commercial space projects is surveyed, with a focus on US programs, in reviews and reports presented at the Second Symposium on Space Industrialization held in Huntsville in February 1984. Areas explored include policy, legal, and economic aspects; communications; materials processing; earth-resources observation; and the role of space carriers and a space station. Also included in the volume are 132 brief descriptions of the NASA Microgravity Science and Applications Program Tasks as of December 1984. These tasks cover the fields electronics materials; solidification of metals, alloys, and composites; fields and transport phenomena; biotechnology; glass and ceramics; combustion science; and experimental technology.

Jernigan, C. M. (editor); Pentecost, E. (editor)

1985-01-01

345

Space Flight Now  

NSDL National Science Digital Library

Space Flight Now offers the latest space news from around the world. Visitors can discover information on current missions, launch schedules, and mission reports. Along with providing the space news headlines, the web site supplies news archives so people can catch up on the activities of the space science world. Visitors can enjoy video footage from cameras onboard recent rocket launches. While users do have to subscribe to obtain many of the videos and audio recordings, individuals can benefit from the free up-to-date astronomy news stories and a few videos.

346

Multimegawatt space power reactors  

NASA Astrophysics Data System (ADS)

In response to the need of the Strategic Defense Initiative (SDI) and long range space exploration and extra-terrestrial basing by the National Air and Space Administration (NASA), concepts for nuclear power systems in the multi-megawatt levels are being designed and evaluated. The requirements for these power systems are being driven primarily by the need to minimize weight and maximize safety and reliability. This paper will discuss the present requirements for space based advanced power systems, technological issues associated with the development of these advanced nuclear power systems, and some of the concepts proposed for generating large amounts of power in space.

Dearien, J. A.; Whitbeck, J. F.

347

Space Shuttle Cockpit  

NASA Technical Reports Server (NTRS)

Want to sit in the cockpit of the Space Shuttle and watch astronauts work in outer space? At StenniSphere, you can do that and much more. StenniSphere, the visitor center at John C. Stennis space Center in Hancock County, Miss., presents 14,000-square-feet of interactive exhibits that depict America's race for space as well as a glimpse of the future. Stennisphere is open free of charge from 9 a.m. to 5 p.m. daily.

2000-01-01

348

Space Shuttle Cockpit exhibit  

NASA Technical Reports Server (NTRS)

Want to sit in the cockpit of the Space Shuttle and watch astronauts work in outer space? At StenniSphere, you can do that and much more. StenniSphere, the visitor center at John C. Stennis Space Center in Hancock County, Miss., presents 14,000-square-feet of interactive exhibits that depict America's race for space as well as a glimpse of the future. StenniSphere is open free of charge from 9 a.m. to 5 p.m. daily.

2000-01-01

349

The space station  

NASA Technical Reports Server (NTRS)

Conceived since the beginning of time, living in space is no longer a dream but rather a very near reality. The concept of a Space Station is not a new one, but a redefined one. Many investigations on the kinds of experiments and work assignments the Space Station will need to accommodate have been completed, but NASA specialists are constantly talking with potential users of the Station to learn more about the work they, the users, want to do in space. Present configurations are examined along with possible new ones.

Munoz, Abraham

1988-01-01

350

Growing plant in space.  

PubMed

Space agencies in several countries are planning for the culture of plants in long duration space bases. The challenge of developing crop production procedures suitable for space projects will result in a new approach of problems we may meet today or in the near future in our common production systems. You may keep in mind subjects as: minimizing wastes or pollution problems, saving materials, introductions robotic helps. Discussion between scientists involved with food production for space programmes and protected horticultural cultivation may open new perspectives. PMID:11538379

Tibbitts, T W; Bula, R J; Tibbits, T W

1989-11-01

351

Commercialization of the Space Frontier  

NASA Technical Reports Server (NTRS)

This paper discusses the current outlook for space business, how growing space business will improve the quality of life for all, and identified strategies for better relating international space research, technology, and space system operations to commercial interests in space. By drawing on recent assessments of the future potential for business in space, opportunities will be defined for encouraging the growth of business uses of space and regaining the public's awareness and support for expanding the space frontier.

Piland, William M.

1997-01-01

352

Space Radiation Protection, Space Weather, and Exploration  

NASA Technical Reports Server (NTRS)

Management of crew exposure to radiation is a major concern for manned spaceflight and will be even more important for the modern concept of longer-duration exploration. The inherent protection afforded to astronauts by the magnetic field of the Earth in Low Earth Orbit (LEO) makes operations on the space shuttle or space station very different from operations during a deep space exploration mission. In order to experience significant radiation-derived Loss of Mission (LOM) or Loss of Crew (LOC) risk for LEO operations, one is almost driven to dictate extreme duration or to dictate an extreme sequence of solar activity. Outside of the geo-magnetosphere, however, this scenario changes dramatically. Exposures to the same event on the ISS and on the surface of the Moon may differ by multiple orders of magnitude. This change in magnitude, coupled with the logistical constraints present in implementing any practical operational mitigation make situational awareness with regard to space weather a limiting factor for our ability to conduct exploration operations. With these differences in risk to crew, vehicle and mission in mind, we present the status of the efforts currently underway as the required development to enable exploration operations. The changes in the operating environment as crewed operations begin to stretch away from the Earth are changing the way we think about the lines between research and operations . The real, practical work to enable a permanent human presence away from Earth has already begun

Zapp, Neal; Fry, Dan; Lee, Kerry

2010-01-01

353

International Space Station from Space Shuttle Endeavour  

NASA Technical Reports Server (NTRS)

The crew of the Space Shuttle Endeavour took this spectacular image of the International Space Station during the STS118 mission, August 8-21, 2007. The image was acquired by an astronaut through one of the crew cabin windows, looking back over the length of the Shuttle. This oblique (looking at an angle from vertical, rather than straight down towards the Earth) image was acquired almost one hour after late inspection activities had begun. The sensor head of the Orbiter Boom Sensor System is visible at image top left. The entire Space Station is visible at image bottom center, set against the backdrop of the Ionian Sea approximately 330 kilometers below it. Other visible features of the southeastern Mediterranean region include the toe and heel of Italy's 'boot' at image lower left, and the western coastlines of Albania and Greece, which extend across image center. Farther towards the horizon, the Aegean and Black Seas are also visible. Featured astronaut photograph STS118-E-9469 was acquired by the STS-118 crew on August 19, 2007, with a Kodak 760C digital camera using a 28 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science and Analysis Laboratory at Johnson Space Center.

2007-01-01

354

Space Station Freedom Utilization Conference  

NASA Technical Reports Server (NTRS)

The topics addressed in Space Station Freedom Utilization Conference are: (1) space station freedom overview and research capabilities; (2) space station freedom research plans and opportunities; (3) life sciences research on space station freedom; (4) technology research on space station freedom; (5) microgravity research and biotechnology on space station freedom; and (6) closing plenary.

1992-01-01

355

Space Operations in the Eighties.  

ERIC Educational Resources Information Center

Highlights activities/accomplishments and future endeavors related to space operations. Topics discussed include the Space Shuttle, recovery/refurbishment operations, payload manipulator, upper stages operations, tracking and data relay, spacelab, space power systems, space exposure facility, space construction, and space station. (JN)

Aviation/Space, 1982

1982-01-01

356

Access to space: The Space Shuttle's evolving rolee  

NASA Astrophysics Data System (ADS)

Access to space is of extreme importance to our nation and the world. Military, civil, and commercial space activities all depend on reliable space transportation systems for access to space at a reasonable cost. The Space Transportation System or Space Shuttle was originally planned to provide transportation to and from a manned Earth-orbiting space station. To justify the development and operations costs, the Space Shuttle took on other space transportation requirements to include DoD, civil, and a growing commercial launch market. This research paper or case study examines the evolving role of the Space Shuttle as our nation's means of accessing space. The case study includes a review of the events leading to the development of the Space Shuttle, identifies some of the key players in the decision-making process, examines alternatives developed to mitigate the risks associated with sole reliance on the Space Shuttle, and highlights the impacts of this national space policy following the Challenger accident.

Duttry, Steven R.

1993-04-01

357

Space Debris Mitigation Guidelines  

NASA Technical Reports Server (NTRS)

The purpose of national and international space debris mitigation guides is to promote the preservation of near-Earth space for applications and exploration missions far into the future. To accomplish this objective, the accumulation of objects, particularly in long-lived orbits, must be eliminated or curtailed.

Johnson, Nicholas L.

2011-01-01

358

Soviet MIR Space Station.  

National Technical Information Service (NTIS)

The purpose of this paper was to determine if the Soviet MIR space station represents a significant advance when compared to the Soviets preceding Salyut 7 space station. A description and comparison of the physical features of Salyut 7 and MIR are presen...

T. E. Snook

1988-01-01

359

Multimegawatt space power reactors  

Microsoft Academic Search

In response to the need of the Strategic Defense Initiative (SDI) and long range space exploration and extra-terrestrial basing by the National Air and Space Administration (NASA), concepts for nuclear power systems in the multi-megawatt levels are being designed and evaluated. The requirements for these power systems are being driven primarily by the need to minimize weight and maximize safety

J. A. Dearien; J. F. Whitbeck

1989-01-01

360

Space Transportation Systems Technologies  

NASA Technical Reports Server (NTRS)

This document is the final report by the Science Applications International Corporation (SAIC) on contracted support provided to the National Aeronautics and Space Administration (NASA) under Contract NAS8-99060, 'Space Transportation Systems Technologies'. This contract, initiated by NASA's Marshall Space Flight Center (MSFC) on February 8, 1999, was focused on space systems technologies that directly support NASA's space flight goals. It was awarded as a Cost-Plus-Incentive-Fee (CPIF) contract to SAIC, following a competitive procurement via NASA Research Announcement, NRA 8-21. This NRA was specifically focused on tasks related to Reusable Launch Vehicles (RLVs). Through Task Area 3 (TA-3), "Other Related Technology" of this NRA contract, SAIC extensively supported the Space Transportation Directorate of MSFC in effectively directing, integrating, and setting its mission, operations, and safety priorities for future RLV-focused space flight. Following an initially contracted Base Year (February 8, 1999 through September 30, 1999), two option years were added to the contract. These were Option Year 1 (October 1, 1999 through September 30, 2000) and Option Year 2 (October 1, 2000 through September 30, 2001). This report overviews SAIC's accomplishments for the Base Year, Option Year 1, and Option Year 2, and summarizes the support provided by SAIC to the Space Transportation Directorate, NASA/MSFC.

Laue, Jay H.

2001-01-01

361

SpaceFibre Discussion  

NASA Technical Reports Server (NTRS)

This viewgraph presentation discusses the future use of SpaceFibre, a high speed optical extension to the SpaceWire, for NASA and DOD missions. NASA, and US industries would like to work with the European developers currently working on this standard.

Rakow, Glenn

2007-01-01

362

LITHIUM BATTERY SPACE EXPERIMENT  

Microsoft Academic Search

The In-Space Technology Experiments Program seleoted the Jet Propulsion Laboratory to conduct a Phase A study of the Lithium Battery Fxperirnent. The experiment will mark the first time a rechargeable lithium battery will be flown in space. The operation of the batlery irrvofves lithium deposition and dissolution processes. Micro gravity influences these processes significantly. The experiment will check the rate

Artur B. Chmlelewski; Subbarao Surampudl; Richard Bennett; Harvey Frank; Robert Mueller

363

Law in Outer Space.  

ERIC Educational Resources Information Center

Provides an overview of the current practice and fascinating future of legal issues involved in outer space exploration and colonization. Current space law, by necessity, addresses broad principles rather than specific incidents. Nonetheless, it covers a variety of issues including commercial development, rescue agreements, object registration,…

Schmidt, William G.

1997-01-01

364

The Deep Space Network  

NASA Technical Reports Server (NTRS)

Deep Space Network progress in flight project support, tracking and data acquisition, research and technology, network engineering, hardware and software implementation, and operations is cited. Topics covered include: tracking and ground based navigation; spacecraft/ground communication; station control and operations technology; ground communications; and deep space stations.

1979-01-01

365

Trajectories For Space Ambulance  

NASA Technical Reports Server (NTRS)

Report presents concept for space ambulance that moves as quickly and economically as possible between orbits. Describes variety of rendezvous maneuvers between space stations in geocentric orbits at altitudes ranging from 200 km to geosynchronous altitude. Analyzes minimum times to complete rendezvous with orbiting medical station.

Nelson, Walter C.; Furakawa, Shiro

1988-01-01

366

Space Weather CD  

NSDL National Science Digital Library

This is a software package about space weather: what it is and what it does in space and here on Earth. The disc includes software that displays movies and images of the aurora and of the Sun in various wavelengths from the ground and from orbiting NASA spacecraft; a tutorial about what space weather is and how the aurora is formed; and more. Users will also find real-time space weather conditions from current satellite missions and can download the latest data without leaving the Space Weather application. A TicTacToe game is also included that tests space weather knowledge. The disc contains many other Space Weather resources, programs, sounds, and games for use at home or school, and there are several educational websites included in full on the disc for offline viewing. In addition there is an exhaustive list of links to a variety of space weather resources available online. The disc is available for free from a number of sites if downloaded.

367

NASA's Space Visualization Studio  

NSDL National Science Digital Library

The mission of the Scientific Visualization Studio is to facilitate scientific inquiry and outreach within NASA programs through visualization. To that end, the SVS works closely with scientists in the creation of visualization products, systems, and processes in order to promote a greater understanding of Earth and Space Science research activities at Goddard Space Flight Center and within the NASA research community.

368

Strange Bedfellows Enchanting Space  

ERIC Educational Resources Information Center

In this article, the author shares her experience working on a multimedia project with her students. The project creates a context for students to reinterpret space and ethos in an elementary school. It allows students to poetically enter physical spaces and the written word through collaborative observation, contemplation, and remixing.

Thulson, Anne

2011-01-01

369

Space station executive summary  

NASA Technical Reports Server (NTRS)

An executive summary of the modular space station study is presented. The subjects discussed are: (1) design characteristics, (2) experiment program, (3) operations, (4) program description, and (5) research implications. The modular space station is considered a candidate payload for the low cost shuttle transportation system.

1972-01-01

370

Space Shuttle Overview  

NASA Technical Reports Server (NTRS)

Many students are not even aware of the many activities related to the US Space Program. The intent of this presentation is to introduce students to the world of space exploration and encourage them to pursue math, science, and engineering careers. If this is not their particular interest, I want to encourage them to pursue their dream.

McNutt, Leslie

2006-01-01

371

A space construction humanoid  

Microsoft Academic Search

A mobile humanoid robot is reconfiguring NASA modular truss structures at the Johnson Space Center. Until recently these structures could only be effectively manipulated by human hands or by robots with specialized end effectors. This humanoid robot, Robonaut, designed to assist astronauts during space walks, has been upgraded to tackle the precision constrained tasks associated with truss assembly and disassembly.

M. A. Diftler; J. S. Mehling; P. A. Strawser; W. R. Doggett; I. M. Spain

2005-01-01

372

Space Station Evolution Study.  

National Technical Information Service (NTIS)

This is the Space Station Freedom (SSF) Evolution Study 1993 Final Report, performed under NASA Contract NAS8-38783, Task Order 5.1. This task examined: (1) the feasibility of launching current National Space Transportation System (NSTS) compatible logist...

D. B. Evans

1993-01-01

373

Space Elevator: Stability  

Microsoft Academic Search

Many papers have been published on engineering and economic aspects of the Space Elevator. The Elevator, however, is a very special and unusual astronomical body. Its behavior in space is affected not only by the attraction of the Earth and by the “centrifugal force” but also by the attraction of the Sun and the Moon, by the detailed shape of

Lubos Perek

2008-01-01

374

Dedicated Space | Poster  

Cancer.gov

The three-story, 330,000-square-foot Advanced Technology Research Facility has nearly 40,000 square feet designated as partnership space (shown in blue) for co-location of collaborators from industry, academia, nonprofit sectors, and other government agencies. The partnership space, combined with multiple conference rooms and meeting areas, encourages both internal and external collaborations.

375

Space stations favored  

Microsoft Academic Search

Recently, Presidential Science Advisor George A. Key worth II created a new wave of enthusiasm about the future of the U.S. space program by stating in Science magazine that the National Aeronautics and Space Administratoin (NASA) should consider a major new initiative (July 8, 1983). Key worth has previously used Science magazine to provide his views on policy to the

Peter M. Bell

1983-01-01

376

Space Shuttle news reference  

NASA Technical Reports Server (NTRS)

A detailed description of the space shuttle vehicle and associated subsystems is given. Space transportation system propulsion, power generation, environmental control and life support system and avionics are among the topics. Also, orbiter crew accommodations and equipment, mission operations and support, and flight crew complement and crew training are addressed.

1981-01-01

377

Space Flight 101.  

National Technical Information Service (NTIS)

This viewgraph presentation reviews many aspects of spaceflight. There are many pictures of the International Space Station. Some of the topics covered in this review are: Have you ever wondered why we have launch windows. Or why the attitude of the Space...

J. Bacon

2006-01-01

378

Moduli Spaces and Grassmannian  

NASA Astrophysics Data System (ADS)

We calculate the homomorphism of the cohomology induced by the Krichever map of moduli spaces of curves into infinite-dimensional Grassmannian. This calculation can be used to compute the homology classes of cycles on moduli spaces of curves that are defined in terms of Weierstrass points.

Liou, Jia-Ming (Frank); Schwarz, A.

2013-06-01

379

The deep space network  

NASA Technical Reports Server (NTRS)

The progress is reported of Deep Space Network (DSN) research in the following areas: (1) flight project support, (2) spacecraft/ground communications, (3) station control and operations technology, (4) network control and processing, and (5) deep space stations. A description of the DSN functions and facilities is included.

1974-01-01

380

Space Mathematics Website  

NSDL National Science Digital Library

This Website contains over 200 authentic math problems that cover solar physics, space physics, radiation dosimetry, and the human impacts of space weather. The problems range from pre-algebra to calculus and span the math skills appropriate for grade 8-12 students. The problems are taken from authentic applications of arithmetic, graph analysis, pre-algebra, and algebra.

2010-09-27

381

Space Ship Pilot Model  

NSDL National Science Digital Library

The Space Ship Pilot model is a model of motion under Newton's laws with and without resistive forces. The first environment puts the user in control of docking a space shuttle, and the second puts the user in control of docking a boat.

Joiner, David; The Shodor Education Foundation, Inc.

382

Space and Atmospheric Environments  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides information on space environments and the protection of materials and structures from their harsh conditions. Space environments are complex, and the complexity of spacecraft systems is increasing. Design accommodation must be realistic. Environmental problems can be limited at low cost relative to spacecraft cost.

Barth, Janet L.; Day, John H. (Technical Monitor)

2002-01-01

383

Space stations favored  

NASA Astrophysics Data System (ADS)

Recently, Presidential Science Advisor George A. Key worth II created a new wave of enthusiasm about the future of the U.S. space program by stating in Science magazine that the National Aeronautics and Space Administratoin (NASA) should consider a major new initiative (July 8, 1983). Key worth has previously used Science magazine to provide his views on policy to the science community; in the past the messages have not been so supportive of the space program, but apparently NASA has made the case for an ambitious plan of space technology and development. The new program may involve space stations to support a colony on the moon (see Eos, April 19, 1983, p. 145) and perhaps Mars.In the July 8 Science, Keyworth is quoted as saying, “I think the country would take a major thrust in space very seriously. We've shown that the shuttle works, and is realistic. We know we have the technolgy to build a space station—most advocates of a space station readily acknowledge that it is only an intermediate step in a more ambitious longrange goal of exploring the solar system.”

Bell, Peter M.

384

Atoms: The Space Between  

NSDL National Science Digital Library

This video segment adapted from A Science Odyssey takes a look at the scale of the atom and the tremendous amount of space between the electrons and the nucleus. If all this empty space exists in matter, how can any substance be solid?

Foundation, Wgbh E.

2004-01-22

385

Spectra from Space  

NSDL National Science Digital Library

This site from the Exploratorium provides information on telescopes and observatories such as the Hubble Space Telescope that are being used to study spectra from space. Gamma-ray, x-ray, ultraviolet, and infrared spectra are all examined. The purpose and discoveries made by each observatory are included along with related hands-on activities like a liquid crystal IR detector activity.

Felter, Neil

2006-07-20

386

Why Explore Space.  

National Technical Information Service (NTIS)

As NASA resumes flights of the space shuttle to finish building the International Space Station (ISS), many question whether the project is worth the risk and expense. This issue was addressed in the report of the Columbia Accident Investigation Board, wh...

M. D. Griffin

2008-01-01

387

?-Spaces: Programming Security Protocols  

Microsoft Academic Search

We introduce ?-Spaces, a domain specific programming language tailored to the development of security protocols. ?-Spaces has a rigorous formal semantics which allows us to reason about the actual implementation of security protocols. In this manner we fill-in the gap between the formal specification of a protocol and its actual implementation.

Giuseppe Milicia

2002-01-01

388

Space-based magnetometers  

Microsoft Academic Search

The general characteristics and system level concepts for space-based magnetometers are presented to illustrate the instruments, principles, and tools involved in making accurate magnetic field measurements in space. Special consideration is given to the most important practical problems that need to be solved to ensure the accuracy of the measurements and their overall impact on system design and mission costs.

Mario H. Acuna

2002-01-01

389

Lubrication of space systems  

NASA Technical Reports Server (NTRS)

NASA has many high-technology programs plannned for the future, such as the space station, Mission to Planet Earth (a series of Earth-observing satellites), space telescopes, and planetary orbiters. These missions will involve advanced mechanical moving components, space mechanisms that will need wear protection and lubrication. The tribology practices used in space today are primarily based on a technology that is more than 20 years old. The question is the following: Is this technology base good enough to meet the needs of these future long-duration NASA missions? This paper examines NASA's future space missions, how mechanisms are currently lubricated, some of the mechanism and tribology challenges that may be encountered in future missions, and some potential solutions to these future challenges.

Fusaro, Robert L.

1994-01-01

390

Human Space Flight  

NASA Technical Reports Server (NTRS)

The first human space flight, in the early 1960s, was aimed primarily at determining whether humans could indeed survive and function in micro-gravity. Would eating and sleeping be possible? What mental and physical tasks could be performed? Subsequent programs increased the complexity of the tasks the crew performed. Table 1 summarizes the history of U.S. space flight, showing the projects, their dates, crew sizes, and mission durations. With over forty years of experience with human space flight, the emphasis now is on how to design space vehicles, habitats, and missions to produce the greatest returns to human knowledge. What are the roles of the humans in space flight in low earth orbit, on the moon, and in exploring Mars?

Woolford, Barbara; Mount, Frances

2004-01-01

391

Space Experiment Module (SEM)  

NASA Technical Reports Server (NTRS)

The Space Experiment Module (SEM) Program is an education initiative sponsored by the National Aeronautics and Space Administration (NASA) Shuttle Small Payloads Project. The program provides nationwide educational access to space for Kindergarten through University level students. The SEM program focuses on the science of zero-gravity and microgravity. Within the program, NASA provides small containers or "modules" for students to fly experiments on the Space Shuttle. The experiments are created, designed, built, and implemented by students with teacher and/or mentor guidance. Student experiment modules are flown in a "carrier" which resides in the cargo bay of the Space Shuttle. The carrier supplies power to, and the means to control and collect data from each experiment.

Brodell, Charles L.

1999-01-01

392

Plants in Space  

NSDL National Science Digital Library

The BioEd Online website is giving interested parties everywhere the opportunity to learn from plants in space. Created in partnership with the National Space Biomedical Research Institute and BioServe Space Technologies of the University of Colorado, the project brings together plants from the International Space Station and plants grown by young people in their respective classrooms. The videos and teacher's guides here will let students perform their own experiments in the classroom based on data from space. Visitors will find PowerPoint presentations here for use in the classroom, along with videos of the plants in different states of germination. The site is rounded out by detailed information about this type of scientific investigation and the National Science Education Standards.

2011-12-21

393

Space station data flow  

NASA Technical Reports Server (NTRS)

The results of the space station data flow study are reported. Conceived is a low cost interactive data dissemination system for space station experiment data that includes facility and personnel requirements and locations, phasing requirements and implementation costs. Each of the experiments identified by the operating schedule is analyzed and the support characteristics identified in order to determine data characteristics. Qualitative and quantitative comparison of candidate concepts resulted in a proposed data system configuration baseline concept that includes a data center which combines the responsibility of reprocessing, archiving, and user services according to the various agencies and their responsibility assignments. The primary source of data is the space station complex which provides through the Tracking Data Relay Satellite System (TDRS) and by space shuttle delivery data from experiments in free flying modules and orbiting shuttles as well as from the experiments in the modular space station itself.

1972-01-01

394

Plants in Space  

NSDL National Science Digital Library

The BioEd Online website is giving interested parties everywhere the opportunity to learn from plants in space. Created in partnership with the National Space Biomedical Research Institute and BioServe Space Technologies of the University of Colorado, the project brings together plants from the International Space Station and plants grown by young people in their respective classrooms. The videos and teacher's guides here will let students perform their own experiments in the classroom based on data from space. Visitors will find Power-Point presentations here for use in the classroom, along with videos of the plants in different states of germination. The site is rounded out by detailed information about this type of scientific investigation and the National Science Education Standards.

395

Teaching With Space  

NSDL National Science Digital Library

Teaching With Space is intended as a resource for teachers who want to introduce their students to space science and technology. A brief, free registration is required to access the educational modules, of which there are five in all. Among the topics are such elements as aerospace technology, "human exploration and development of space," and methods of teaching with technology. Each of the modules begins with a short quiz to assess the user's familiarity with the subject. One section contains slide presentations about the International Space Station, while others provide educational insights into various space-related concepts. Because of the amount of information presented on this site, anyone, not just teachers, could benefit from the material.

1969-12-31

396

Space and Time  

NSDL National Science Digital Library

This fun Web site is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they are introduced to space and time with six engaging and kid-friendly areas: Welcome to the Fourth Dimension, which looks at how time is needed to describe where you are in the fourth dimension; It's All Relative, an explanation of how time and space are different depending on your frame of reference; Mass Appeal, which uses the example of an elephant on a page of paper to explain how the Sun's mass causes space and time to bend; You Light Up My Life, how Arthur Eddington proved that Einstein's light-bending prediction was right; Everyday Einstein: Black Holes, an overview of these "bottomless dimples in space." and Time Travel Kit, a look at how the faster you move in space, the slower you move in time.

397

Wireless Communications in Space  

NASA Technical Reports Server (NTRS)

In 1992, NASA and the U.S. Department of Defense jointly commissioned the research and development of a technology solution to address the challenges and requirements of communicating with their spacecraft. The project yielded an international consortium composed of representatives from the space science community, industry, and academia. This group of experts developed a broad suite of protocols specifically designed for space-based communications, known today as Space Communications Protocol Standards (SCPS). Having been internationally standardized by the Consultative Committee on Space Data Systems and the International Standards Organization, SCPS is distributed as open source technology by NASA s Jet Propulsion Laboratory (JPL). The protocols are used for every national space mission that takes place today.

2004-01-01

398

Space Station Food System  

NASA Technical Reports Server (NTRS)

A team of engineers and food scientists from NASA, the aerospace industry, food companies, and academia are defining the Space Station Food System. The team identified the system requirements based on an analysis of past and current space food systems, food systems from isolated environment communities that resemble Space Station, and the projected Space Station parameters. The team is resolving conflicts among requirements through the use of trade-off analyses. The requirements will give rise to a set of specifications which, in turn, will be used to produce concepts. Concept verification will include testing of prototypes, both in 1-g and microgravity. The end-item specification provides an overall guide for assembling a functional food system for Space Station.

Thurmond, Beverly A.; Gillan, Douglas J.; Perchonok, Michele G.; Marcus, Beth A.; Bourland, Charles T.

1986-01-01

399

Space station, 1959 to . .  

NASA Astrophysics Data System (ADS)

Early space station designs are considered, taking into account Herman Oberth's first space station, the London Daily Mail Study, the first major space station design developed during the moon mission, and the Manned Orbiting Laboratory Program of DOD. Attention is given to Skylab, new space station studies, the Shuttle and Spacelab, communication satellites, solar power satellites, a 30 meter diameter radiometer for geological measurements and agricultural assessments, the mining of the moons, and questions of international cooperation. It is thought to be very probable that there will be very large space stations at some time in the future. However, for the more immediate future a step-by-step development that will start with Spacelab stations of 3-4 men is envisaged.

Butler, G. V.

1981-04-01

400

Atoms for space  

SciTech Connect

Nuclear technology offers many advantages in an expanded solar system space exploration program. These cover a range of possible applications such as power for spacecraft, lunar and planetary surfaces, and electric propulsion; rocket propulsion for lunar and Mars vehicles; space radiation protection; water and sewage treatment; space mining; process heat; medical isotopes; and self-luminous systems. In addition, space offers opportunities to perform scientific research and develop systems that can solve problems here on Earth. These might include fusion and antimatter research, using the Moon as a source of helium-3 fusion fuel, and manufacturing perfect fusion targets. In addition, nuclear technologies can be used to reduce risk and costs of the Space Exploration Initiative. 1 fig.

Buden, D.

1990-10-01

401

Human factors: Space  

NASA Technical Reports Server (NTRS)

The objectives are to provide a technology base for intelligent operator interfaces, especially with autonomous subsystems, and to develop a new generation of high performance space suits, gloves, and tools/end effectors to meet the requirements of advanced space missions. The technology base is intended to meet the requirements of productivity, efficiency, and safety in complex manned operations within automated onboard systems and extravehicular activities (EVA) environments. Crew station research is the first of two major areas. Development of methods for the astronaut to supervise, monitor, and evaluate the performance of robotic systems, other space subsystems, and orbital vehicles are key areas of research. The second major area is development of an EVA space suit and gloves. Emphasis in the space human factors research program is placed on technology baseline studies and development of methods, techniques, and data to support productive and safe operations by the astronaut and crew as they interface with complex systems, advance automation, and robotic assistants.

Jenkins, James P.

1988-01-01

402

Cassava For Space Diet  

NASA Astrophysics Data System (ADS)

Space agriculture is an advanced life support enginnering concept based on biological and ecological system ot drive the materials recycle loop and create pleasant life environment on distant planetary bodies. Choice of space diet is one of primary decision required ot be made at designing space agriculture. We propose cassava, Manihot esculenta and, for one major composition of space food materials, and evaluate its value and feasibility of farming and processing it for space diet. Criteria to select space crop species could be stated as follows. 1) Fill th enutritional requirements. There is no perfect food material to meet this requirements without making a combination with others. A set of food materials which are adopted inthe space recipe shall fit to the nutritional requirement. 2) Space food is not just for maintaining physiological activities of human, but an element of human culture. We shall consider joy of dining in space life. In this context, space foos or recipe should be accepted by future astronauts. Food culture is diverse in the world, and has close relatioship to each cultural background. Cassava root tuber is a material to supply mainly energy in the form of carbohydrate, same as cereals and other tuber crops. Cassava leaf is rich in protein high as 5.1 percents about ten times higher content than its tuber. In the food culture in Africa, cassava is a major component. Cassava root tuber in most of its strain contains cyanide, it should be removed during preparation for cooking. However certain strain are less in this cyanogenic compound, and genetically modified cassava can also aboid this problem safely.

Katayama, Naomi; Yamashita, Masamichi; Njemanze, Philip; Nweke, Felix; Mitsuhashi, Jun; Hachiya, Natumi; Miyashita, Sachiko; Hotta, Atuko

403

Space station thermal control surfaces. [space radiators  

NASA Technical Reports Server (NTRS)

Mission planning documents were used to analyze the radiator design and thermal control surface requirements for both space station and 25-kW power module, to analyze the missions, and to determine the thermal control technology needed to satisfy both sets of requirements. Parameters such as thermal control coating degradation, vehicle attitude, self eclipsing, variation in solar constant, albedo, and Earth emission are considered. Four computer programs were developed which provide a preliminary design and evaluation tool for active radiator systems in LEO and GEO. Two programs were developed as general programs for space station analysis. Both types of programs find the radiator-flow solution and evaluate external heat loads in the same way. Fortran listings are included.

Maag, C. R.; Millard, J. M.; Jeffery, J. A.; Scott, R. R.

1979-01-01

404

Space Radiation Protection, Space Weather, and Exploration  

NASA Technical Reports Server (NTRS)

Management of crew exposure to radiation is a major concern for manned spaceflight -- and will be even more important for the modern concept of longer-duration exploration. The inherent protection afforded to astronauts by the magnetic field of the Earth in Low Earth Orbit (LEO) makes operations on the space shuttle or space station very different from operations during an exploration mission. In order to experience significant radiation-derived Loss of Mission (LOM) or Loss of Crew (LOC) risk for LEO operations, one is almost driven to dictate extreme duration or to dictate an extreme sequence of solar activity. Outside of the geo-magnetosphere, however, this scenario changes dramatically. Exposures to the same event on the ISS and on the surface of the Moon may differ by multiple orders of magnitude. This change in magnitude, coupled with the logistical constraints present in implementing any practical operational mitigation make situational awareness with regard to space weather a limiting factor for our ability to conduct exploration operations. With these differences in risk to crew, vehicle and mission in mind, we present the status of the efforts currently underway as the required development to enable exploration operations. The changes in the operating environment as crewed operations begin to stretch away from the Earth are changing the way we think about the lines between "research" and "operations". The real, practical work to enable a permanent human presence away from Earth has already begun.

Zapp, Neal; Rutledge, R.; Semones, E. J.; Johnson, A. S.; Guetersloh, S.; Fry, D.; Stoffle, N.; Lee, K.

2008-01-01

405

The Rocks From Space 'Space Safari  

NASA Astrophysics Data System (ADS)

We describe an integrated online science programme incorporating Moodle virtual learning environments (VLEs) and Elluminate Live! virtual classrooms. The "Space Safari" was run as part of the Rocks From Space (RFS) programme hosted at The Open University (OU) and in partnership with Stockton City Learning Centre (SCLC). Schools used these resources for direct science teaching or to incorporate them into the wider curriculum (arts/literature etc), after which they produce an output. Emphasis was on providing links between schools and scientists within the higher education sector. Live sessions with experts via Elluminate Live! were held regularly, including sessions with NASA scientists and astronomers in Mallorca. Teachers and students have used Space Safari resources as part of the school science curriculum and to develop key skills and additional curriculum skills. They have also used it for informal (forums, online discussions) opportunities to engage with science. Over 3 years of the project, over 1500 students have engaged, with the project. The use of virtual classrooms enabled direct interaction with many students; one session alone involved over 100 students. This project is now hosted on the eTwinning portal to enable sustainability and widen access.

Pearson, Victoria; Brooks, Val

2010-05-01

406

Skylab, Space Shuttle, Space Benefits Today and Tomorrow.  

ERIC Educational Resources Information Center

The pamphlet "Skylab" describes very generally the kinds of activities to be conducted with the Skylab, America's first manned space station. "Space Shuttle" is a pamphlet which briefly states the benefits of the Space Shuttle, and a concise review of present and future benefits of space activities is presented in the pamphlet "Space Benefits…

National Aeronautics and Space Administration, Washington, DC.

407

Space charge measurement techniques and space charge in polyethylene  

Microsoft Academic Search

Recently, several new techniques such as LIPP, PIPS, PEA and TP methods have been developed to measure directly the space charge distributions in insulating polymers. Many papers have been published on space charge in insulating materials. In this paper, the space charge measurement techniques and space charge in polyethylene are reviewed. The space charge distributions in polyethylene depend strongly upon

T. Mizutani

1994-01-01

408

Managing the space sciences  

NASA Technical Reports Server (NTRS)

In April 1994 the National Research Council received a request from NASA that the NRC's Space Studies Board provide guidance on questions relating to the management of NASA's programs in the space sciences. The issues raised in the request closely reflect questions posed in the agency's fiscal year 1994 Senate appropriations report. These questions included the following: Should all the NASA space science programs be gathered into a 'National Institute for Space Science'? What other organizational changes might be made to improve the coordination and oversight of NASA space science programs? What processes should be used for establishing interdisciplinary science priorities based on scientific merit and other criteria, while ensuring opportunities for newer fields and disciplines to emerge? And what steps could be taken to improve utilization of advanced technologies in future space scienc missions? This report details the findings of the Committee on the Future of Space Science (FOSS) and its three task groups: the Task Group on Alternative Organizations, Task Group on Research Prioritization, and the Task Group on Technology.

1995-01-01

409

The manned space station  

NASA Astrophysics Data System (ADS)

The development and establishment of a manned space station represents the next major U.S. space program after the Space Shuttle. If all goes according to plan, the space station could be in orbit around the earth by 1992. A 'power tower' station configuration has been selected as a 'reference' design. This configuration involves a central truss structure to which various elements are attached. An eight-foot-square truss forms the backbone of a structure about 400 feet long. At its lower end, nearest the earth, are attached pressurized manned modules. These modules include two laboratory modules and two so-called 'habitat/command' modules, which provide living and working space for the projected crew of six persons. Later, the station's pressurized space would be expanded to accommodate up to 18 persons. By comparison, the Soviets will provide habitable space for 12 aboard a 300-ton station which they are expected to place in orbit. According to current plans the six U.S. astronauts will work in two teams of three persons each. A ninety-day tour of duty is considered.

Kovit, B.

410

Tribology Experiments in Space  

NASA Astrophysics Data System (ADS)

Brief history of tribology experiments in space is described. Tribological performance in a high vacuum was a great concern in early stage of space development, and it was urgent task to verify whether the actual space environment can be simulated using ground-based vacuum facilities from tribological viewpoint. Some friction tests as well as bearing tests were carried out on board satellites in 1960s, and the conclusion was that the results of space experiments was very similar to those of ground-based comparison experiments. In 1980s, however, Space Shuttle flown in Low Earth Orbit (LEO) revealed a new problem; oxidization by active atomic oxygen, which is more than 90% constituent in the environment. Some types of solid lubricants might be oxidized, and thus lost tribological effectiveness. Efforts to clarify the effect of LEO environment on solid lubricants, as well as to simulate LEO environment properly, have been devoted including space experiments. Recent tribology-related space experiments are briefly reviewed.

Suzuki, Mineo

411

Advanced space transportation technologies  

NASA Technical Reports Server (NTRS)

A wide range of propulsion technologies for space transportation are discussed in the literature. It is clear from the literature review that a single propulsion technology cannot satisfy the many mission needs in space. Many of the technologies tested, proposed, or in experimental stages relate to: chemical and nuclear fuel; radiative and corpuscular external energy source; tethers; cannons; and electromagnetic acceleration. The scope and limitation of these technologies is well tabulated in the literature. Prior experience has shown that an extensive amount of fuel needs to be carried along for the return mission. This requirement puts additional constraints on the lift off rocket technology and limits the payload capacity. Consider the possibility of refueling in space. If the return fuel supply is guaranteed, it will not only be possible to lift off more payload but also to provide security and safety of the mission. Exploration to deep space where solar sails and thermal effects fade would also be possible. Refueling would also facilitate travel on the planet of exploration. This aspect of space transportation prompts the present investigation. The particle emissions from the Sun's corona will be collected under three different conditions: in space closer to the Sun, in the Van Allen Belts; and on the Moon. It is proposed to convert the particle state into gaseous, liquid, or solid state and store it for refueling space vehicles. These facilities may be called space pump stations and the fuel collected as space fuel. Preliminary estimates of fuel collection at all three sites will be made. Future work will continue towards advancing the art of collection rate and design schemes for pumping stations.

Raj, Rishi S.

1989-01-01

412

Why Not Space Tethers?  

NASA Technical Reports Server (NTRS)

The Tethered Satellite System Space Shuttle missions, TSS-1 in 1993 and TSS-1R in 1996, were the height of space tether technology development. Since NASA's investment of some $200M and two Shuttle missions in those two pioneering missions, there have been several smaller tether flight experiments, but interest in this promising technology has waned within NASA as well as the DOD agencies. This is curious in view of the unique capabilities of space tether systems and the fact that they have been flight validated and shown to perform as, or better than, expected in earth orbit. While it is true that the TSS-1, TSS-1R and SEDS-2 missions experienced technical difficulties, the causes of these early developmental problems are now known to be design or materials flaws that are (1) unrelated to the basic viability of space tether technology, and (2) they are readily corrected. The purpose of this paper is to review the dynamic and electrodynamic fundamentals of space tethers and the unique capabilities they afford (that are enabling to certain types of space missions); to elucidate the nature, cause, and solution of the early developmental problems; and to provide an update on progress made in development of the technology. Finally, it is shown that (1) all problems experienced during early development of the technology now have solutions; and (2) the technology has been matured by advances made in strength and robustness of tether materials, high voltage engineering in the space environment, tether health and status monitoring, and the elimination of the broken tether hazard. In view of this, it is inexplicable why this flight-validated technology has not been utilized in the past decade, considering the powerful and unique capabilities that space tethers can afford that are, not only required to carryout, otherwise, unobtainable missions, but can also greatly reduce the cost of certain on-going space operations.

Stone, Noble H.

2007-01-01

413

Space Shuttle Aging Elastomers  

NASA Technical Reports Server (NTRS)

The reusable Manned Space Shuttle has been flying into Space and returning to earth for more than 25 years. The Space Shuttle's uses various types of elastomers and they play a vital role in mission success. The Orbiter has been in service well past its design life of 10 years or 100 missions. As part of the aging vehicle assessment one question under evaluation is how the elastomers are performing. This paper will outline a strategic assessment plan, how identified problems were resolved and the integration activities between subsystems and Aging Orbiter Working Group.

Curtis, Cris E.

2007-01-01

414

Boeing: Defense, Space & Security  

NSDL National Science Digital Library

Boeing plays a key role in the scientific exploration of space, and has for many years. On this Web site, Boeing outlines numerous projects and developments currently underway. There are five general areas of the site, which include launch and orbital systems, human spaceflight and exploration, global connectivity, integrated battlespace, and missile defense. Each of these sections offers detailed information about specific products and research. There is extensive material about the International Space Station, space shuttle design and potential upgrades, and satellite systems. Image galleries and videos are also included, illustrating the exciting work being done for government and commercial applications.

2002-01-01

415

Space Movies Cinema  

NSDL National Science Digital Library

NASA'S Space Movies Cinema site contains thirty-four viewable movies relating to space exploration. Ever wanted to see the golf shot that Alan Shepard hit on the moon, the first flag on the moon, or even a morph of an astronaut into a robot or an astronaut suit into body armor? This site has these and more, giving visitors a literal look back at the history of space exploration in the United States with interesting and fun movies. The movies (most of which are only fair quality) come with a short description and a link for either a .mov or .avi file.

Woodfill, Jerry.

2000-01-01

416

Rocket and Space Technology  

NSDL National Science Digital Library

Orbital mechanics, propulsion, rocket hardware, space centers and missions are among the topics featured on Robert A. Braeunig's Rocket and space Technology page. Braeunig is a civil engineer whose hobby is learning about space flight. This page is well-researched, and all sources are credited. The text disseminates relatively simple explanations of the mechanics of rocket flight and includes definitions of important terms and black-and-white diagrams. Sample problems, tables, and formulas make the site useful to secondary educators and students. The science and mathematics behind everything from building a spacecraft to launching it are covered in this instructional site.

Braeunig, Robert A.

2001-01-01

417

Space engine safety system  

NASA Technical Reports Server (NTRS)

A rocket engine safety system was designed to initiate control procedures to minimize damage to the engine or vehicle or test stand in the event of an engine failure. The features and the implementation issues associated with rocket engine safety systems are discussed, as well as the specific concerns of safety systems applied to a space-based engine and long duration space missions. Examples of safety system features and architectures are given, based on recent safety monitoring investigations conducted for the Space Shuttle Main Engine and for future liquid rocket engines. Also, the general design and implementation process for rocket engine safety systems is presented.

Maul, William A.; Meyer, Claudia M.

1991-01-01

418

Life in Space  

NSDL National Science Digital Library

In this video lecture, Helen Sharman, the first British astronaut, gives an account of her personal experiences on the space station Mir. Using models and film to illustrate key scientific concepts, she discusses the way the Third Law of Newton and convection apply to rockets, space flight, weightlessness and survival. Sharman explains how breathing, eating, using the toilet, and recycling were accomplished on Mir. She answers questions from an audience of young school children (aged 9-12 years) about weightlessness, the effect of space on bones and joints, and the training of astronauts. The video is 29 minutes in length.

419

Expandable space frames  

NASA Technical Reports Server (NTRS)

Expandable space frames having essentially infinite periodicity limited only by practical considerations, are described. Each expandable space frame comprises a plurality of hinge joint assemblies having arms that extend outwardly in predetermined symmetrically related directions from a central or vertex point. The outer ends of the arms form one part of a hinge point. The outer expandable space frame also comprises a plurality of struts. The outer ends of the struts from the other part of the hinged joint. The struts interconnect the plurality of hinge point in sychronism, the spaceframes can be expanded or collapsed. Three-dimensional as well as two-dimensional spaceframes of this general nature are described.

Schoen, A. H. (inventor)

1973-01-01

420

Space station parametric models  

NASA Technical Reports Server (NTRS)

The development of two parametric models for a four-panel planar initial space station is described. The derivations of the distributed parameter model are presented in detail with the hope that the same method and procedures can be employed for stations with different configurations or for changes within the same configuration class. The 19-DOF finite-element model is also described. With the availability of the 19-DOF and a lower-DOF space station models, the frequency characteristics of the various dynamical systems in the space station environment are identified.

Hamidi, M.; Wang, S. J.

1985-01-01

421

Fundamentals of Space Medicine  

NASA Astrophysics Data System (ADS)

A total of more than 240 human space flights have been completed to date, involving about 450 astronauts from various countries, for a combined total presence in space of more than 70 years. The seventh long-duration expedition crew is currently in residence aboard the International Space Station, continuing a permanent presence in space that began in October 2000. During that time, investigations have been conducted on both humans and animal models to study the bone demineralization and muscle deconditioning, space motion sickness, the causes and possible treatment of postflight orthostatic intolerance, the changes in immune function, crew and crew-ground interactions, and the medical issues of living in a space environment, such as the effects of radiation or the risk of developing kidney stones. Some results of these investigations have led to fundamental discoveries about the adaptation of the human body to the space environment. Gilles Clément has been active in this research. This readable text presents the findings from the life science experiments conducted during and after space missions. Topics discussed in this book include: adaptation of sensory-motor, cardio-vascular, bone, and muscle systems to the microgravity of spaceflight; psychological and sociological issues of living in a confined, isolated, and stressful environment; operational space medicine, such as crew selection, training and in-flight health monitoring, countermeasures and support; results of space biology experiments on individual cells, plants, and animal models; and the impact of long-duration missions such as the human mission to Mars. The author also provides a detailed description of how to fly a space experiment, based on his own experience with research projects conducted onboard Salyut-7, Mir, Spacelab, and the Space Shuttle. Now is the time to look at the future of human spaceflight and what comes next. The future human exploration of Mars captures the imagination of both the public and the scientific community. Many physiological, psychological, operational, and scientific issues need to be solved before the first crew can explore the enigmatic Red Planet. This book also identifies the showstoppers that can be foreseen and what we need to learn to fully understand the implications and risks of such a mission.

Clément, Gilles

2005-03-01

422

Fundamentals of Space Medicine  

NASA Astrophysics Data System (ADS)

As of today, a total of more than 240 human space flights have been completed, involving about 450 astronauts from various countries, for a combined total presence in space of more than 70 years. The seventh long-duration expedition crew is currently in residence aboard the International Space Station, continuing a permanent presence in space that began in October 2000. During that time, investigations have been conducted on both humans and animal models to study the bone demineralization and muscle deconditioning, space motion sickness, the causes and possible treatment of postflight orthostatic intolerance, the changes in immune function, crew and crew-ground interactions, and the medical issues of living in a space environment, such as the effects of radiation or the risk of developing kidney stones. Some results of these investigations have led to fundamental discoveries about the adaptation of the human body to the space environment. Gilles Clément has been active in this research. This book presents in a readable text the findings from the life science experiments conducted during and after space missions. Topics discussed in this book include: adaptation of sensory-motor, cardiovascular, bone and muscle systems to the microgravity of spaceflight; psychological and sociological issues of living in a confined, isolated and stressful environment; operational space medicine, such as crew selection, training and in-flight health monitoring, countermeasures and support; results of space biology experiments on individual cells, plants, and animal models; and the impact of long-duration missions such as the human mission to Mars. The author also provides a detailed description of how to fly a space experiment, based on his own experience with research projects conducted onboard Salyut-7, Mir, Spacelab, and the Space Shuttle. Now is the time to look at the future of human spaceflight and what comes next. The future human exploration of Mars captures the imagination of both the public and the scientific community. Many physiological, psychological, operational, and scientific issues need to be solved before the first crew will explore the enigmatic Red Planet. This book also identifies the showstoppers that can be foreseen and what do we need to learn to understand fully the implications and risks of such a mission. Link: http://www.wkap.nl/prod/b/1-4020-1598-4>

Clément, G.

2003-10-01

423

Evolution to Space  

NASA Technical Reports Server (NTRS)

This presentation will discuss recent space exploration results (LCROSS, KEPLER, etc.), increase access to space and the small and cube satellites platform as it relates to the future of space exploration. It will highlight the concept of modularization and the use of biology, and specifically synthetic biology in the future. The presentation will be a general public presentation. When speaking to a younger audience, I will discuss my background. All slides contain only public information. No technical ITAR/Export controlled material will be discussed.

Cohen, Jacob

2013-01-01

424

Detroit space odessey  

NASA Technical Reports Server (NTRS)

The symposium included personal appearances by NASA astronauts, NASA exhibits, aerospace science lecture demonstrations (Spacemobile Lectures), and talks on job opportunities in aerospace and on the benefits of the Space Program. The program was directed mainly at (public, parochial and private) student groups, each of which spent three hours at the symposium site, Wayne State University campus, to participate in the symposium activities. The symposium was open to the general public and consisted of the NASA exhibits, aerospace science lecture demonstrations, films, talks on the benefits of the space program, and a special tasting demonstration of ""space food'' meal systems.

Allen, H., Jr.

1983-01-01

425

Space, time, and gravitation  

NASA Astrophysics Data System (ADS)

A popular survey of the evolution of ideas of space, time, and gravitation from antiquity to the present day is given. The main stages in the development of general relativity are summarized. Fundamental results of current relativity theory are reviewed, including the equivalence principle and gravitational redshift, Schwarzschild space-time, the riddle of Mercury, gravitational lenses, and the monad method. Prospects of the further development of space-time theory are discussed; attention is given to gravitational waves, black holes, and generalizations of Einstein's gravitation theory.

Vladimirov, Iu. S.; Mitskevich, N. V.; Horsky, J.

426

SpaceCube Mini  

NASA Technical Reports Server (NTRS)

This version of the SpaceCube will be a full-fledged, onboard space processing system capable of 2500+ MIPS, and featuring a number of plug-andplay gigabit and standard interfaces, all in a condensed 3x3x3 form factor [less than 10 watts and less than 3 lb (approximately equal to 1.4 kg)]. The main processing engine is the Xilinx SIRF radiation- hardened-by-design Virtex-5 FX-130T field-programmable gate array (FPGA). Even as the SpaceCube 2.0 version (currently under test) is being targeted as the platform of choice for a number of the upcoming Earth Science Decadal Survey missions, GSFC has been contacted by customers who wish to see a system that incorporates key features of the version 2.0 architecture in an even smaller form factor. In order to fulfill that need, the SpaceCube Mini is being designed, and will be a very compact and low-power system. A similar flight system with this combination of small size, low power, low cost, adaptability, and extremely high processing power does not otherwise exist, and the SpaceCube Mini will be of tremendous benefit to GSFC and its partners. The SpaceCube Mini will utilize space-grade components. The primary processing engine of the Mini is the Xilinx Virtex-5 SIRF FX-130T radiation-hardened-by-design FPGA for critical flight applications in high-radiation environments. The Mini can also be equipped with a commercial Xilinx Virtex-5 FPGA with integrated PowerPCs for a low-cost, high-power computing platform for use in the relatively radiation- benign LEOs (low-Earth orbits). In either case, this version of the Space-Cube will weigh less than 3 pounds (.1.4 kg), conform to the CubeSat form-factor (10x10x10 cm), and will be low power (less than 10 watts for typical applications). The SpaceCube Mini will have a radiation-hardened Aeroflex FPGA for configuring and scrubbing the Xilinx FPGA by utilizing the onboard FLASH memory to store the configuration files. The FLASH memory will also be used for storing algorithm and application code for the PowerPCs and the Xilinx FPGA. In addition, it will feature highspeed DDR SDRAM (double data rate synchronous dynamic random-access memory) to store the instructions and data of active applications. This version will also feature SATA-II and Gigabit Ethernet interfaces. Furthermore, there will also be general-purpose, multi-gigabit interfaces. In addition, the system will have dozens of transceivers that can support LVDS (low-voltage differential signaling), RS-422, or SpaceWire. The SpaceCube Mini includes an I/O card that can be customized to meet the needs of each mission. This version of the SpaceCube will be designed so that multiple Minis can be networked together using SpaceWire, Ethernet, or even a custom protocol. Scalability can be provided by networking multiple SpaceCube Minis together. Rigid-Flex technology is being targeted for the construction of the SpaceCube Mini, which will make the extremely compact and low-weight design feasible. The SpaceCube Mini is designed to fit in the compact CubeSat form factor, thus allowing deployment in a new class of missions that the previous SpaceCube versions were not suited for. At the time of this reporting, engineering units should be available in the summer 2012.

Lin, Michael; Petrick, David; Geist, Alessandro; Flatley, Thomas

2012-01-01

427

How have we explored space?  

NSDL National Science Digital Library

Many individuals have helped us advance in our space explorations - let's take a look at these advancements in our space program! We have come to the end of the space shuttle program, yet through the past 30 years it has made strides to help us develop the International Space Station. We will continue on with our discoveries and explorations of space! Launch Discovery launches to International Space Station Journey to the Space Station Journey to Space Station Mission Highlights of STS131 STS 131 Mission Highlights Landing Discovery Landing at Kennedy Space Center New Era of ...

Keller, Mrs.

2010-05-01

428

Space industrialization studies - An overview  

NASA Technical Reports Server (NTRS)

An overview of NASA's current planning for a space industrialization program is described as an introduction to the papers on Space Industrialization being presented by Rockwell International Corporation and Science Applications Incorporated. Background information is presented that outlines the integrated planning process which resulted in specific long range goals and objectives being formulated for NASA programs in technology, environment, resources, earth science, communications, space exploration, aeronautics, and an expanded application of space called space industrialization. Program objectives for NASA's Industrialization of Space and studies on potential near term supporting elements (Space Platform, Large Space Structures, Orbital Operations Capabilities Development, Space Manufacturing Module) are discussed.

Priest, C.; Bradford, R.

1977-01-01

429

Space technology developments in Malaysia  

Microsoft Academic Search

The venture of space is, by nature, a costly one. However, exploring space is not just an activity reserved for international superpowers. Smaller and emerging space nations, some with burgeoning space programs of their own, can play a role in space technology development and interplanetary exploration, sometimes simply by just being there. Over the past four decades, the range of

A. Sabirin

2004-01-01

430

Achievable Space Elevators for Space Transportation and Starship Acceleration.  

National Technical Information Service (NTIS)

Space elevator concepts for low-cost space launches are reviewed. Previous concepts suffered from requirements for ultra-high-strength materials, dynamically unstable systems, or from danger of collision with space debris. The use of magnetic grain stream...

J. Pearson

1990-01-01

431

ISS Update: SpaceX Space Act Agreement Status  

NASA Video Gallery

NASA Public Affairs Officer Kyle Herring interviews Jon Cowart, Commercial Crew Program, Partner Manager for Space Exploration Technologies (SpaceX), about the status of Space Act Agreement. Questi...

432

Space robotics in Japan  

NASA Technical Reports Server (NTRS)

Japan has been one of the most successful countries in the world in the realm of terrestrial robot applications. The panel found that Japan has in place a broad base of robotics research and development, ranging from components to working systems for manufacturing, construction, and human service industries. From this base, Japan looks to the use of robotics in space applications and has funded work in space robotics since the mid-1980's. The Japanese are focusing on a clear image of what they hope to achieve through three objectives for the 1990's: developing long-reach manipulation for tending experiments on Space Station Freedom, capturing satellites using a free-flying manipulator, and surveying part of the moon with a mobile robot. This focus and a sound robotics infrastructure is enabling the young Japanese space program to develop relevant systems for extraterrestrial robotics applications.

Whittaker, William; Lowrie, James W.; Mccain, Harry; Bejczy, Antal; Sheridan, Tom; Kanade, Takeo; Allen, Peter

1994-01-01

433

The classroom space project  

NSDL National Science Digital Library

Classroom Space is a national education project funded by PPARC and run by the University of Leicester, in collaboration with the National Space Centre. It aims to revitalize science education at Key Stages 3 and 4 by using exciting examples from Space Science and Astronomy to illustrate key science concepts. The comprehensive classroom resources-which are available to download free of charge from the project website www.classroomspace.org.uk-are all linked to the National Curriculum and are fully self-contained. The materials are developed through partnership between space scientists, teachers and education professionals. The project was launched at the ASE Annual Meeting in January, and this paper summarizes the motivation for the project and its development, as well as looking forward to ideas for an extension to the project for which funding has been confirmed.

Verbickas, Sarah

2005-11-28

434

Space-Age Shades  

NASA Technical Reports Server (NTRS)

Silhouette's Titan Minimal Art frames possess a super elasticity that ensures a slip-free fit for wearing comfort, without causing irritating pressure points. The titanium alloy used in the frames also prevents allergic reactions. This technology is available to both NASA astronauts and public consumers in either corrective eyewear or sunglass models. The only difference between the sunwear used by NASA astronauts and the commercial models is the lens. Silhouette and Dr. Keith Manuel, the "official" optometrist overseeing the NASA Space Shuttle, the International Space Station, and various other vision-related space projects, brought NASA a lens that is considerably darker (5.5 percent overall light transmittance), with a thin gold coating that offers total protection, not only against ultraviolet (UV) radiation, but also against the harmful infrared radiation in space.

2002-01-01

435

Technologies. [space power sources  

NASA Technical Reports Server (NTRS)

Energy technologies to meet the power requirements of future space missions are reviewed. Photovoltaic, solar dynamic, and solar thermal technologies are discussed along with techniques for energy storage and power management and distribution.

Brandhorst, Henry W., Jr.

1992-01-01

436

The deep space network  

NASA Technical Reports Server (NTRS)

The functions and facilities of the Deep Space Network are considered. Progress in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations is reported.

1980-01-01

437

Kids in space  

NASA Astrophysics Data System (ADS)

The 81st mission in NASA's space shuttle program was the 2nd for KidSat, a program to bring space exploration down to Earth for middle and high school students. A joint program of NASA's Jet Propulsion Laboratory (JPL), the University of California at San Diego (UCSD), and the Johns Hopkins University Institute for the Academic Advancement of Youth, the KidSat program allows students to direct the operation of a camera mounted on space shuttle Atlantis.After the launch of Atlantis on January 12, a KidSat operations center (modeled after Mission Control at Johnson Space Center) went on-line at UCSD, staffed by undergraduate and high school students. Those students receive telemetry directly from the shuttle and are able to listen to communication between NASA's flight controllers and astronauts. The KidSat operations center processes and delivers up-to-the-minute information about the shuttle to 15 middle schools in the United States.

Carlowicz, Michael

438

Electrophoresis experiments for space  

NASA Astrophysics Data System (ADS)

It has long been hoped that space could alleviate the problems of large-scale, high-capacity electrophoresis. Support media and reduced chamber dimensions of capillary electrophoresis have established the physical boundaries for Earth-based systems. Ideally, electrophoresis conducted in a virtual weightless environment in an unrestricted ``free'' fluid should have great potential. The electrophoresis and isoelectric focusing experiments done in the reduced gravity over the past twenty-five years have demonstrated the absence of thermal convection and sedimentation as well as the presence of electrohydrodynamics that requires careful control. One commercial venture produced gram amounts of an electrophoretically purified protein during seven Space Shuttle flights but the market disappeared in the six years between experiment conception and performance on the Space Shuttle. Our accumulated experience in microgravity plus theoretical models predict improvements that should be possible with electrophoresis if past problems are considered and both invention of new technologies and innovation of procedures on the Space Station are encouraged. .

Snyder, Robert S.; Rhodes, Percy H.

2000-01-01

439

Space Station Software Recommendations  

NASA Technical Reports Server (NTRS)

Four panels of invited experts and NASA representatives focused on the following topics: software management, software development environment, languages, and software standards. Each panel deliberated in private, held two open sessions with audience participation, and developed recommendations for the NASA Space Station Program. The major thrusts of the recommendations were as follows: (1) The software management plan should establish policies, responsibilities, and decision points for software acquisition; (2) NASA should furnish a uniform modular software support environment and require its use for all space station software acquired (or developed); (3) The language Ada should be selected for space station software, and NASA should begin to address issues related to the effective use of Ada; and (4) The space station software standards should be selected (based upon existing standards where possible), and an organization should be identified to promulgate and enforce them. These and related recommendations are described in detail in the conference proceedings.

Voigt, S. (editor)

1985-01-01