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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

Intergalactic Dust  

NASA Astrophysics Data System (ADS)

We study the composition and sizes of intergalactic dust based on the expulsion of interstellar dust from the galactic disk. Interstellar grains in the Galactic disk are modelled as a mixture of amorphous silicate dust and carbonaceous dust consisting of polycyclic aromatic hydrocarbon (PAH) molecules and larger graphitic grains (Li & Draine 2001) with size distributions like those of the Milky Way dust (Weingartner & Draine 2001). We model their dynamic evolution in terms of the collective effects caused by (1) radiative acceleration, (2) gravitational attraction, (3) gas drag, (4) thermal sputtering, and (5) Lorenz force from the galactic magnetic field (Ferrara et al. 1991). Radiation pressure from the stellar disk exerts an upward force on dust grains and may ultimately expel them out of the entire galaxy. Gravitational force from the stellar, dust and gas disk as well as the dark matter halo exerts a downward force. Thermal sputtering erodes all grains to some degree but more efficiently destroys small grains. This, together with the fact that (1) very small grains (with small radiation pressure efficiencies) are not well coupled to starlight; (2) for large grains the radiative force to the gravitational force is approximately inversely proportional to grain size, acts as a size ``filter'' for dust leaking into the intergalactic space. Since the radiation pressure efficiency and the grain destruction rate are sensitive to dust composition, the relative importance of carbon dust compared to silicate dust expelled into the intergalactic space differs from that in the galactic plane. We derive the size distributions of both silicate and carbonaceous dust finally getting into the intergalactic space and obtain an intergalactic extinction curve. The predicted intergalactic infrared emission spectrum is calculated. References: Ferrara, A., Ferrini, F., Franco, J., & Barsella, B. 1991, ApJ, 381, 137 Li, A., & Draine, B.T. 2001, ApJ, 554, 778 Weingartner, J.C., & Draine, B.T. 2001, ApJ, 548, 296

Li, A.

2002-12-01

3

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

4

Testing a novel method to map the 3D distribution of gas clouds in intergalactic space  

E-print Network

We propose a new method to detect intergalactic Lyman a emitter and absorber systems by comparing broadband and narrowband images. The narrowband observations were carried out with the Maryland-Magellan Tunable Filter ...

Bardalez Gagliuffi, Daniella C

2011-01-01

5

Scatter broadening of compact radio sources by the ionized intergalactic medium: prospects for detection with Space VLBI and the Square Kilometre Array  

NASA Astrophysics Data System (ADS)

We investigate the feasibility of detecting and probing various components of the ionized intergalactic medium (IGM) and their turbulent properties at radio frequencies through observations of scatter broadening of compact sources. There is a strong case for conducting targeted observations to resolve scatter broadening (where the angular size scales as ˜?-2) of compact background sources intersected by foreground galaxy haloes and rich clusters of galaxies to probe the turbulence of the ionized gas in these objects, particularly using Space very long baseline interferometry (VLBI) with baselines of 350 000 km at frequencies below 800 MHz. The sensitivity of the Square Kilometre Array (SKA) allows multifrequency surveys of interstellar scintillation (ISS) of ˜ 100 ?Jy sources to detect or place very strong constraints on IGM scatter broadening down to ˜ 1 ?as scales at 5 GHz. Scatter broadening in the warm-hot component of the IGM with typical overdensities of ˜30 cannot be detected, even with Space VLBI or ISS, and even if the outer scales of turbulence have an unlikely low value of ˜1 kpc. None the less, intergalactic scatter broadening can be of the order of ˜ 100 ?as at 1 GHz and ˜ 3 ?as at 5 GHz for outer scales ˜1 kpc, assuming a sufficiently high-source redshift that most sight-lines intersect within a virial radius of at least one galaxy halo (z ? 0.5 and 1.4 for 1010 and 1011 M? systems, following McQuinn 2014). Both Space VLBI and multiwavelength ISS observations with the SKA can easily test such a scenario, or place strong constraints on the outer scale of the turbulence in such regions.

Koay, J. Y.; Macquart, J.-P.

2015-01-01

6

Intergalactic Star Formation  

E-print Network

Star formation in interacting systems may take place in various locations, from the dust--enshrouded core of Ultraluminous Infrared Galaxies to more unusual places such as the debris of colliding galaxies expelled into the intergalactic medium. Determining whether star-formation proceeds in the latter environment, far from the parent galaxies, in a similar way as in spiral disks has motivated the multi--wavelength study presented here. We collected VLA/HI, UV/GALEX, optical Halpha and MIR/Spitzer images of a few nearby interacting systems chosen for their prominent "intergalactic" star formation activity. Preliminary results on the spectacular collisional HI ring around NGC 5291 are presented.

Pierre-Alain Duc; Meederic Boquien; Jonathan Braine; Elias Brinks; Ute Lisenfeld; Vassilis Charmandaris

2006-10-13

7

Intergalactic HI Clouds  

E-print Network

Neutral intergalactic clouds are so greatly out numbered by galaxies that their integral HI content is negligible in comparison to that contained in optically luminous galaxies. In fact, no HI cloud that is not associated with a galaxy or grouping of galaxies has yet been identified. This points to a causal relationship that relies on gravitational potentials that bind galaxies also being responsible for confining HI clouds to sufficient density that they can become self-shielding to the ionizing background radiation. Unconfined clouds of low density become ionized, but confined clouds find themselves vulnerable to instability and collapse, leading to star formation.

F. H. Briggs

2005-02-16

8

On the intergalactic attenuation for high-z galaxies  

NASA Astrophysics Data System (ADS)

Even after the cosmic reionization, neutral hydrogen still remains in the intergalactic space. These intervening hydrogen atoms absorb the radiation from high-z objects and make a numerous absorption lines, the so-called Lyman alpha forest, in the spectra of the objects. To know the absorption amount as a function of redshift is essentially important for studies of the high-z objects, for example, to predict how much reddening occurs in the spectra of the high-z galaxies, which is used as the so-called Lyman break technique. The current standard model for the intergalactic attenuation is Madau (1995). However, the intergalactic absorbers' statistics, which is the ingredient of the model, is largely updated during two decades after Madau (1995). Here, I present an update of this kind model. I also show a preliminary result of the absorption excess in a proto-cluster environment found in a composite spectrum of galaxies behind the proto-cluster.

Inoue, Akio K.

2015-01-01

9

A SEARCH FOR DUST EMISSION IN THE LEO INTERGALACTIC CLOUD  

SciTech Connect

We present a search for infrared dust emission associated with the Leo cloud, a large intergalactic cloud in the M96 group. Mid-infrared and far-infrared images were obtained with the InfraRed Array Camera and the Multiband Imaging Photometer for Spitzer on the Spitzer Space Telescope. Our analysis of these maps is done at each wavelength relative to the H I spatial distribution. We observe a probable detection at 8 {mu}m and a marginal detection at 24 {mu}m associated with the highest H I column densities in the cloud. At 70 and 160 {mu}m, upper limits on the dust emission are deduced. The level of the detection is low so that the possibility of a fortuitous cirrus clump or of an overdensity of extragalactic sources along the line of sight cannot be excluded. If this detection is confirmed, the quantities of dust inferred imply a dust-to-gas ratio in the intergalactic cloud up to a few times solar but no less than 1/20 solar. A confirmed detection would therefore exclude the possibility that the intergalactic cloud has a primordial origin. Instead, this large intergalactic cloud could therefore have been formed through interactions between galaxies in the group.

Bot, Caroline; Helou, George; Puget, Jeremie [California Institute of Technology, Pasadena, CA 91125 (United States); Latter, William B. [NASA Herschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Schneider, Stephen [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Terzian, Yervant [Department of Astronomy/NAIC, Cornell University, Ithaca, NY 14853 (United States)], E-mail: bot@astro.u-strasbg.fr

2009-08-15

10

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

11

The Clustering of Intergalactic Metals  

E-print Network

We measure the spatial clustering of metals in the intergalactic medium from z = 1.7 to 3.0, as traced by 643 CIV and 104 SiIV N >= 10^12 cm^-2 absorption systems in 19 high signal-to-noise (40-80) and high resolution (R = 45000) quasar spectra. The number densities and two-point correlation functions of both these species are largely constant with redshift, suggesting the bulk of metal ejection occurred at z >= 3. However, at z = M_s, and use numerical simulations to derive best-fit values of R_s ~ 2 comoving Mpc and M_s ~ 5x10^11 solar masses at z = 3. This does not exclude that metals could have been produced at higher redshifts in smaller, but equally rare, objects. At the level of detection of this survey, IGM enrichment is likely to be incomplete and inhomogeneous, with a filling factor ~ 10%.

Christophe Pichon; Evan Scannapieco; Bastien Aracil; Patrick Petitjean; Dominique Aubert; Jacqueline Bergeron; Stephane Colombi

2003-09-23

12

Intergalactic shells at large redshift  

NASA Technical Reports Server (NTRS)

The intergalactic shells produced by galactic explosions at large redshift, whose interiors cool by inverse Compton scattering off the cosmic background radiation, have a characteristic angular size of about 1 arcmin at peak brightness. At z values lower than 2, the shells typically have a radius of 0.5 Mpc, a velocity of about 50 km/sec, a metal abundance of about 0.0001 of cosmic values, and strong radiation in H I(Lyman-alpha), He II 304 A, and the IR fine-structure lines of C II and Si II. The predicted extragalactic background emission from many shells, strongly peaked toward the UV, sets an upper limit to the number of exploding sources at z values of about 10. Shell absorption lines of H I, C II, Si II, and Fe II, which may be seen at more recent epochs in quasar spectra, may probe otherwise invisible explosions in the early universe.

Shull, J. M.; Silk, J.

1981-01-01

13

The Intergalactic Absorption Effect in Blazar Gamma-ray Spectra  

NASA Astrophysics Data System (ADS)

We calculate the optical depth of the universe for gamma-rays having energies between 4 GeV and 100 TeV emitted by sources at redshifts from 0 to 5. Absorption of high energy gamma-rays in intergalactic space is due to interactions with the cosmic background radiation and low energy photons. We calculate the intergalactic photon density in a ΛCDM universe consistent with the most recent WMAP findings as a function of both energy and redshift for 0 < z < 6 and for photon energies from .003 eV up to the Lyman limit cutoff at 13.6 eV. Our evolution model is consistent with Spitzer deep number counts and the spectral energy distribution of the extragalactic background radiation. From our optical depth results, we derive a simple analytic approximation for determining the effect of intergalactic absorption for 0.01 < Ï,, < 100 and for gamma-ray energies up to 2 TeV for all redshifts but also for energies up to 10 TeV for redshifts less than 1. We show the utility of this approximation by applying it to the spectra of seven TeV blazers.

Scully, Sean; Stecker, F.

2007-05-01

14

The Physics and Early History of the Intergalactic Medium  

E-print Network

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 basic cosmological parameters. 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, radiation from the earliest generation of stars is thought to have transformed the universe, turning the surrounding atoms into free electrons and ions. 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. Cosmic reionization is beginning to be understood with the help of theoretical models and computer simulations. A wide variety of instruments currently under design 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. (abridged)

Rennan Barkana; Abraham Loeb

2007-04-26

15

INTERGALACTIC 'PIPELINE' FUNNELS MATTER BETWEEN COLLIDING GALAXIES  

NASA Technical Reports Server (NTRS)

This visible-light picture, taken by NASA's Hubble Space Telescope, reveals an intergalactic 'pipeline' of material flowing between two battered galaxies that bumped into each other about 100 million years ago. The pipeline [the dark string of matter] begins in NGC 1410 [the galaxy at left], crosses over 20,000 light-years of intergalactic space, and wraps around NGC 1409 [the companion galaxy at right] like a ribbon around a package. Although astronomers have taken many stunning pictures of galaxies slamming into each other, this image represents the clearest view of how some interacting galaxies dump material onto their companions. These results are being presented today at the 197th meeting of the American Astronomical Society in San Diego, CA. Astronomers used the Space Telescope Imaging Spectrograph to confirm that the pipeline is a continuous string of material linking both galaxies. Scientists believe that the tussle between these compact galaxies somehow created the pipeline, but they're not certain why NGC 1409 was the one to begin gravitationally siphoning material from its partner. And they don't know where the pipeline begins in NGC 1410. More perplexing to astronomers is that NGC 1409 is seemingly unaware that it is gobbling up a steady flow of material. A stream of matter funneling into the galaxy should have fueled a spate of star birth. But astronomers don't see it. They speculate that the gas flowing into NGC 1409 is too hot to gravitationally collapse and form stars. Astronomers also believe that the pipeline itself may contribute to the star-forming draught. The pipeline, a pencil-thin, 500 light-year-wide string of material, is moving a mere 0.02 solar masses of matter a year. Astronomers estimate that NGC 1409 has consumed only about a million solar masses of gas and dust, which is not enough material to spawn some of the star-forming regions seen in our Milky Way. The low amount means that there may not be enough material to ignite star birth in NGC 1409, either. The glancing blow between the galaxies was enough, however, to toss stars deep into space and ignite a rash of star birth in NGC 1410. The arms of NGC 1410, an active, gas-rich spiral galaxy classified as a Seyfert, are awash in blue, the signature color of star-forming regions. The bar of material bisecting the center of NGC 1409 also is a typical byproduct of galaxy collisions. Astronomers expect more fireworks to come. The galaxies are doomed to continue their game of 'bumper cars,' hitting each other and moving apart several times until finally merging in another 200 million years. The galaxies' centers are only 23,000 light-years apart, which is slightly less than Earth's distance from the center of the Milky Way. They are bound together by gravity, orbiting each other at 670,000 miles an hour (1 million kilometers an hour). The galaxies reside about 300 million light-years from Earth in the constellation Taurus. The Hubble picture was taken Oct. 25, 1999. Credits: NASA, William C. Keel (University of Alabama, Tuscaloosa)

2002-01-01

16

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

17

The Sources of Intergalactic Metals  

E-print Network

We study the clustering properties of metals in the intergalactic medium (IGM) as traced by 619 CIV, 81 SiIV, N >= 10^12 cm^-2 and 316 MgII, and 82 FeII N >= 10^11.5 cm^-2 absorption components in 19 high signal-to-noise (60-100 per pixel), high resolution (R = 45000) quasar spectra. Over the redshift range probed (1.5-3.0), CIV and SiIV trace each other closely and their line-of-sight correlation functions 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 column depth. Carrying out a detailed SPH simulation (2 X 320^3, 57 Mpc^3 comoving), we show that this behavior can not be reproduced by models in which the IGM metallicity is constant or a local function of density. However, the CIV correlation function is consistent with a model in which metals are confined within bubbles with a typical radius Rs = 2 comoving Mpc about sources of mass >= Ms = 10^12 solar masses 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, and the turn-over is shifted to ~ 75 km s^-1. Again these features do not change with column depth. We describe an analytical bubble model for these species, which come from regions that are too compact to be simulated numerically, deriving best-fit values of R_s ~ 2.4 Mpc and M_s ~ 10^12 solar masses. Equally good 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 3 x 10^9 solar mass sources at z = 7.5.

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

2005-02-28

18

Cosmological Blastwaves and the Intergalactic Medium  

E-print Network

Winds from protogalactic starbursts and quasars can drive shocks that heat, ionize, and enrich the intergalactic medium. The Sedov-Taylor solution for point-like explosions adequately describes these blastwaves early in their development, but as the time since the explosion ($t - t_1$) approaches the age of the universe ($t$), cosmological effects begin to alter the blastwave's structure and growth rate. This paper presents an analytical solution for adiabatic blastwaves in an expanding universe, valid when the IGM is homogeneous and contains only a small fraction of the total mass density ($\\Omega_{\\rm IGM} << \\Omega_0$). Using this analytical solution, we examine the role protogalactic explosions might play in determining the state of intergalactic gas at $z \\sim 2 - 4$.

G. Mark Voit

1996-05-13

19

Cluster of galaxies as a probe of the intergalactic medium  

NASA Technical Reports Server (NTRS)

The use of galactic clusters as probes of the intercluster medium is discussed, and the effects of a postulated hot intercluster medium on the diffuse gas associated with clusters of galaxies is examined. It is shown that diffuse intracluster gas, which is observed at X-ray wavelengths, is a powerful probe of intergalactic space. The consequences of conduction are explored and the existence and properties of the intracluster gas are used to constrain the temperature and density of a uniform gas filling the universe. The effects of a nonuniform medium on the results are discussed and it is shown that for plausible scenarios the evaporative mass loss rates are insensitive to changes in the density and temperature of the intracluster medium in the vicinity of clusters. The parameters such a gas would have to have in order to explain the larger energy per unit mass found in the intracluster gas compared to that in galaxies are calculated.

Forman, W.; Jones, C.; Tucker, W.

1984-01-01

20

Can Cosmic Rays Heat the Intergalactic Medium?  

E-print Network

Supernova explosions in the early star forming galaxies will accelerate cosmic rays (CRs). CRs are typically confined in the collapsed objects for a short period before escaping into the intergalactic medium (IGM). Galactic outflows can facilitate this escape by advecting CRs into the IGM. An outflow that results in a termination shock can also generate more CRs. We show that the CR protons from the above processes can significantly affect the thermal history of the IGM. Within plausible range of parameters, cosmic ray heating can compensate for adiabatic cooling and explain the measured IGM temperature at redshifts z between 2 to 4, even with early reionization.

Saumyadip Samui; Kandaswamy Subramanian; Raghunathan Srianand

2005-05-30

21

Thermal Evolution of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The thermal evolution of the intergalactic medium (IGM) can provide clues regarding the reionization history of the IGM. Recent temperature measurements of the IGM from Lyman alpha forest data have given insight into the timeline of these reionization events, specifically the reionization of HeII at z~3. We model the thermal history of the IGM from HI reionization through HeII reionization based on well established heating and cooling processes. We present a comparison of such modeling of the thermal evolution with the recent observational constraints anddiscuss additional heating mechanisms.

Upton Sanderbeck, Phoebe; McQuinn, Matthew

2015-01-01

22

Can Cosmic Rays Heat the Intergalactic Medium?  

E-print Network

Supernova explosions in the early star forming galaxies will accelerate cosmic rays (CRs). CRs are typically confined in the collapsed objects for a short period before escaping into the intergalactic medium (IGM). Galactic outflows can facilitate this escape by advecting CRs into the IGM. An outflow that results in a termination shock can also generate more CRs. We show that the CR protons from the above processes can significantly affect the thermal history of the IGM. Within plausible range of parameters, cosmic ray heating can compensate for adiabatic cooling and explain the measured IGM temperature at redshifts z between 2 to 4, even with early reionization.

Samui, S; Srianand, R; Samui, Saumyadip; Subramanian, Kandaswamy; Srianand, Raghunathan

2005-01-01

23

The Ionization History of The Intergalactic Medium:  

NASA Technical Reports Server (NTRS)

The funded project seeked a unified description of the ionization, physical structure, and evolution of the intergalactic medium (IGM) and quasar intervening absorption systems. We proposed to conduct theoretical studies of the IGM and QSO absorbers in the context of current theories of galaxy formation, developing and using numerical and analytical techniques aimed at a detailed modeling of cosmological radiative transfer, gas dynamics, and thermal and ionization evolution. The ionization history of the IGM has important implications for the metagalactic UV background, intergalactic helium absorption 21-cm tomography, metal absorption systems, fluctuations in the microwave background, and the cosmic rate of structure and star formation. All the original objectives of our program have been achieved, and the results widely used and quoted by the community. Indeed, they remain relevant as the level and complexity of research in this area has increased substantially since our proposal was submitted, due to new discoveries on galaxy formation and evolution, a flood of high-quality data on the distant universe, new theoretical ideas and direct numerical simulations of structure formation in hierarchical clustering theories.

Madau, Piero

2003-01-01

24

A NEW WAY OF DETECTING INTERGALACTIC BARYONS  

SciTech Connect

For each photon wave packet of extragalactic light, the dispersion by line-of-sight intergalactic plasma causes an increase in the envelope width and a chirp (drift) in the carrier frequency. It is shown that for continuous emission of many temporally overlapping wave packets with random epoch phases such as quasars in the radio band, this in turn leads to quasi-periodic variations in the intensity of the arriving light on timescales between the coherence time (defined as the reciprocal of the bandwidth of frequency selection, taken here as of order 0.01 GHz for radio observations) and the stretched envelope, with most of the fluctuation power on the latter scale which is typically in the millisecond range for intergalactic dispersion. Thus, by monitoring quasar light curves on such short scales, it should be possible to determine the line-of-sight plasma column along the many directions and distances to the various quasars, affording one a three-dimensional picture of the ionized baryons in the near universe.

Lieu, Richard; Duan Lingze [Department of Physics, University of Alabama, Huntsville, AL 35899 (United States)

2013-02-01

25

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

26

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

27

Athena and the Missing Baryons in a Warm-Hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Baryons are missing at all astronomical scales in the Universe, from galaxies to the large scales of structure formation and the Universe as a whole. Hydro-dynamical simulations for the formation of structures, tend to reconcile the different 'missing-baryon' problems and predict that most of the baryonic matter of the Universe is hiding in a hot and tenuous gaseous phase (dubbed the 'Warm-Hot Intergalactic Medium, or WHIM), surrounding virialized structures and more at large in the low-redshift inter-galactic space. The only way to secure the detection of this important and highly elusive baryonic component of the Universe, to constrain its physical, chemical and dynamical states, and so to measure its cosmological mass density, is by observing the intergalactic medium with instruments characterized by large collecting areas at the energies at which these baryons are supposed to shine, the soft X-ray band, and spectral resolution sufficient to resolve the weak emission and absorption lines produced by the hot light metals (mainly C, O, Ne) in the WHIM. The X-IFU of Athena, with its 2 m2 effective area at 1 keV and its superb 2.5 eV spectral resolution, will be a powerful WHIM machine. Here I will first summarize the current state of the art and will then focus on the large impulse that Athena will provide for such a rich and still relatively unexplored field of research.

Nicastro, Fabrizio; Kaastra, Jelle; Finoguenov, Alexis

28

The intergalactic medium in the cosmic web  

NASA Astrophysics Data System (ADS)

We request funding to perform a dedicated survey and analysis of theHST archive of COS-G130M quasar spectra to construct anabsorption-line catalog tuned to study the environment {i.e. large-scalestructure, LSS} of the intergalactic medium {IGM}. Specifically, wewill characterize the HI Lyman series absorption at z<0.1 andassociate metals for all absorbers along 100 quasar sightlinespenetrating the SDSS footprint. Using standard line-profile fittingtechniques, we will recover HI column densities and Dopplerparameters. These will be publicly released in a database thatincludes spectral masks identifying spurious spectral features,regions biased by previously known systems, etc. This catalog will beanalyzed in conjunction with the suite of LSS catalogs generated fromthe SDSS footprint {e.g. clusters, groups}, with emphasis on newalgorithms designed to identify and characterize galaxy voids.Through this analysis, we will test the predictions from ourcosmological paradigm that the IGM traces a so-called cosmic web ofLSS.

Tejos, Nicolas

2014-10-01

29

The Connection Between Galaxies and Intergalactic Absorption Lines at Redshift 2  

E-print Network

Absorption-line spectroscopy of 23 background QSOs and numerous background galaxies has let us measure the spatial distribution of metals and neutral hydrogen around 1044 UV-selected galaxies at redshifts 1.8260 km/s) and produces very strong absorption lines (N_CIV >> 10^14 cm^-2) in the spectra of background objects. Absorption with an average column density of N_CIV ~ 10^14 cm^-2 extends to 80 kpc, a radius large enough to imply that most strong intergalactic CIV absorption is associated with star-forming galaxies like those in our sample. We find that the galaxy-CIV cross-correlation length increases with CIV column density and is similar to the galaxy-galaxy length (r_0 ~ 4 h^-1 Mpc) for N_CIV > 10^12.5 cm^-2. Distortions in the redshift-space galaxy-CIV correlation function on small scales may imply that some of the CIV systems have large peculiar velocities. Four of the five detected OVI absorption systems in our sample lie within 400 proper kpc of a known galaxy. Strong Lyman-a absorption is produced by the intergalactic gas within 1 h^-1 comoving Mpc of most galaxies, but for a significant minority (~1/3) the absorption is weak or absent. We were unable to identify any statistically significant differences between galaxies with weak nearby HI absorption and the rest, although galaxies with weak absorption may have higher star-formation rates. Galaxies near intergalactic CIV systems appear to reside in relatively dense environments and to have distinctive spectral energy distributions that are characterized by blue colors and young ages. (abridged)

K. L. Adelberger; A. E. Shapley; C. C. Steidel; M. Pettini; D. K. Erb; N. A. Reddy

2005-05-06

30

Soft X-Ray Absorption by High-Redshift Intergalactic Helium.  

PubMed

The Lyalpha absorption from intergalactic, once-ionized helium (He ii) has been measured with the Hubble Space Telescope in four quasars over the last few years in the redshift range 2.4intergalactic medium (IGM) can be completely optically thick to Lyalpha photons when only a small fraction of the helium remains as He ii. In addition, finding quasars in which the He ii Lyalpha absorption can be observed becomes increasingly difficult at higher redshift owing to the large abundance of hydrogen Lyman limit systems. It is pointed out here that He ii in the IGM should also cause detectable continuum absorption in the soft X-rays. The spectrum of a high-redshift source seen behind the IGM when most of the helium was He ii should recover from the He ii Lyman continuum absorption at an observed energy of approximately 0.1 keV. Galactic absorption will generally be stronger, but not by a large factor; the intergalactic He ii absorption can be detected as an excess over the expected Galactic absorption from the 21 cm H i column density. In principle, this method allows a direct determination of the fraction of helium that was singly ionized as a function of redshift if the measurement is done on a large sample of high-redshift sources over a range of redshifts. PMID:10587481

Miralda-Escudé

2000-01-01

31

Quasar Absorbers and the InterGalactic Medium  

E-print Network

Quasar Absorbers and the InterGalactic Medium Simon C. Reynolds 8 March 2007 1 Introduction When we measure the spectra of quasars, we see many absorption lines super- imposed on the quasars' own emission spectra. These absorption features trace the intervening gas along our line of sight (LOS) to any quasar

Tittley, Eric

32

Giant Intergalactic Gas Stream Longer Than Thought  

NASA Astrophysics Data System (ADS)

A giant stream of gas flowing from neighbor galaxies around our own Milky Way is much longer and older than previously thought, astronomers have discovered. The new revelations provide a fresh insight on what started the gaseous intergalactic streamer. The astronomers used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to fill important gaps in the picture of gas streaming outward from the Magellanic Clouds. The first evidence of such a flow, named the Magellanic Stream, was discovered more than 30 years ago, and subsequent observations added tantalizing suggestions that there was more. However, the earlier picture showed gaps that left unanswered whether this other gas was part of the same system. "We now have answered that question. The stream is continuous," said David Nidever, of the University of Virginia. "We now have a much more complete map of the Magellanic Stream," he added. The astronomers presented their findings to the American Astronomical Society's meeting in Washington, DC. The Magellanic Clouds are the Milky Way's two nearest neighbor galaxies, about 150,000 to 200,000 light-years distant from the Milky Way. Visible in the Southern Hemisphere, they are much smaller than our Galaxy and may have been distorted by its gravity. Nidever and his colleagues observed the Magellanic Stream for more than 100 hours with the GBT. They then combined their GBT data with that from earlier studies with other radio telescopes, including the Arecibo telescope in Puerto Rico, the Parkes telescope in Australia, and the Westerbork telescope in the Netherlands. The result shows that the stream is more than 40 percent longer than previously known with certainty. One consequence of the added length of the gas stream is that it must be older, the astronomers say. They now estimate the age of the stream at 2.5 billion years. The revised size and age of the Magellanic Stream also provides a new potential explanation for how the flow got started. "The new age of the stream puts its beginning at about the time when the two Magellanic Clouds may have passed close to each other, triggering massive bursts of star formation," Nidever explained. "The strong stellar winds and supernova explosions from that burst of star formation could have blown out the gas and started it flowing toward the Milky Way," he said. "This fits nicely with some of our earlier work that showed evidence for just such blowouts in the Magellanic Clouds," said Steven Majewski, of the University of Virginia. Earlier explanations for the stream's cause required the Magellanic Clouds to pass much closer to the Milky Way, but recent orbital simulations have cast doubt on such mechanisms. Nidever and Majewski worked with Butler Burton of the Leiden Observatory and the National Radio Astronomy Observatory, and Lou Nigra of the University of Wisconsin. In addition to presenting the results to the American Astronomical Society, the scientists have submitted a paper to the Astrophysical Journal.

2010-01-01

33

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

34

Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas  

SciTech Connect

Dark Matter annihilations after recombination and during the epoch of structure formation deposit energy in the primordial intergalactic medium, producing reionization and heating. We investigate the constraints that are imposed by the observed optical depth of the Universe and the measured temperature of the intergalactic gas. We find that the bounds are significant, and have the power to rule out large portions of the 'DM mass/cross section' parameter space. The optical depth bound is generally stronger and does not depend significantly on the history of structure formation. The temperature bound can be competitive in some cases for small masses or the hadronic annihilation channels (and is affected somewhat by the details of structure formation). We find in particular that DM particles with a large annihilation cross section into leptons and a few TeV mass, such as those needed to explain the PAMELA and FERMI+HESS cosmic ray excesses in terms of Dark Matter, are ruled out as they produce too many free electrons. We also find that low mass particles (?< 10 GeV) tend to heat too much the gas and are therefore disfavored.

Cirelli, Marco; Iocco, Fabio; Panci, Paolo, E-mail: marco.cirelli@cea.fr, E-mail: iocco@iap.fr, E-mail: Paolo.Panci@aquila.infn.it [Institut de Physique Théorique, CNRS URA 2306 and CEA/Saclay, F-91191 Gif-sur-Yvette (France)

2009-10-01

35

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

36

Cosmic far ultraviolet background. [observations for intergalactic medium properties  

NASA Technical Reports Server (NTRS)

The expected intensities of various possible components of the far ultraviolet background are discussed. It is concluded that existing results do not place interesting constraints on the density of the intergalactic medium (IGM). Current techniques and instrumentation for far ultraviolet astronomy are, however, sufficient to achieve vastly improved limits. New observations are required to determine whether the IGM can be detected in the far ultraviolet or whether the extragalactic component of the background is masked by radiation with a more local origin.

Davidsen, A.; Bowyer, S.; Lampton, M.

1974-01-01

37

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

38

High-metallicity, photoionized gas in intergalactic large-scale filaments  

NASA Astrophysics Data System (ADS)

We present high-resolution ultraviolet spectra of absorption-line systems towards the low-z quasi-stellar object (QSO) HS 0624+6907 (zQSO= 0.3700). Coupled with ground-based imaging and spectroscopic galaxy redshifts, we find evidence that many of these absorbers do not arise in galaxy haloes but rather are truly intergalactic gas clouds distributed within large-scale structures, and moreover, the gas is cool (T < 105 K) and has relatively high metallicity (Z > 0.9Zsolar). Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) data reveal a dramatic cluster of 13 HI Lyman ? (Ly?) lines within a 1000 km s-1 interval at zabs= 0.0635. We find 10 galaxies at this redshift with impact parameters ranging from ?= 135h-170 kpc to 1.37h-170 Mpc. The velocities and velocity spread of the Ly? lines in this complex are unlikely to arise in the individual haloes of the nearby galaxies; instead, we attribute the absorption to intragroup medium gas, possibly from a large-scale filament viewed along its long axis. Contrary to theoretical expectations, this gas is not the shock-heated warm-hot intergalactic medium (WHIM); the width of the Ly? lines all indicate a gas temperature T<< 105 K, and metal lines detected in the Ly? complex also favour photoionized, cool gas. No OVI absorption lines are evident, which is consistent with photoionization models. Remarkably, the metallicity is near-solar, [M/H]=-0.05 +/- 0.4 (2? uncertainty), yet the nearest galaxy which might pollute the intergalactic medium is at least 135h-170 kpc away. Tidal stripping from nearby galaxies appears to be the most likely origin of this highly enriched, cool gas. More than six Abell galaxy clusters are found within 4° of the sight line suggesting that the QSO line of sight passes near a node in the cosmic web. At z~ 0.077, we find absorption systems as well as galaxies at the redshift of the nearby clusters Abell 564 and Abell 559. We conclude that the sight line pierces a filament of gas and galaxies feeding into these clusters. The absorber at zabs= 0.07573 associated with Abell 564/559 also has a high metallicity with [C/H] > -0.6, but again the closest galaxy is relatively far from the sight line (?= 293h-170 kpc). The Doppler parameters and HI column densities of the Ly? lines observed along the entire sight line are consistent with those measured towards other low-z QSOs, including a number of broad (b > 40kms-1) Ly? lines.

Aracil, Bastien; Tripp, Todd M.; Bowen, David V.; Prochaska, Jason X.; Chen, Hsiao-Wen; Frye, Brenda L.

2006-03-01

39

Hunting for the missing baryons in the warm-hot intergalactic medium  

NASA Astrophysics Data System (ADS)

We discuss the physical properties and the baryonic content of the warm-hot intergalactic medium (whim) at low redshifts. Cosmological simulations predict that the whim contains a large fraction of the baryons at z=0 in the form of highly-ionised gas at temperatures between 105 and 107 k. Using high-resolution ultraviolet spectra obtained with the space telescope imaging spectrograph (stis) and the far ultraviolet spectroscopic explorer (FUSE) we have studied the whim at low redshifts by searching for intervening O VI and thermally broadened Lyman ? (bla) absorption toward a number of quasars and active galactic nuclei (AGNs). Our measurements imply cosmological mass densities of ?b(O VI)?0.0022 h75-1 and ?b(bla)?0.0035 h75-1. Our results suggest that the whim at low z contains more baryonic mass than stars and gas in galaxies.

Richter, P.; Savage, B. D.; Tripp, T. M.; Sembach, K. R.

2005-03-01

40

Intergalactic thermonuclear gamma-ray line  

NASA Technical Reports Server (NTRS)

The possibility of thermonculear reactions occurring in dilute space is briefly considered. X-ray emission from clusters of galaxies demonstrates that perhaps as much as 10 to the 14th solar masses of hot gas (T of about 100 million K) may often surround galaxies in clusters with a density of perhaps 0.004/cu cm. If the ion temperature is 100 million K, the thermonuclear reaction p + d to He-3 + gamma ray should emit gamma rays at a rate of roughly 4 x 10 to the 41st/sec with energy 5.516 + or -0.016 MeV. Such a source in teh virgo cluster at 15.7 Mpc would present a line flux of 1 x 10 to the -11th/sq cm/sec.

Clayton, D. D.

1985-01-01

41

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

42

Intergalactic Extinction of High Energy Gamma-Rays  

NASA Technical Reports Server (NTRS)

We discuss the determination of the intergalactic pair-production absorption coefficient as derived by Stecker and De Jager by making use of a new empirically based calculation of the spectral energy distribution of the intergalactic infrared radiation field as given by Malkan and Stecker. We show that the results of the Malkan and Stecker calculation agree well with recent data on the infrared background. We then show that Whipple observations of the flaring gamma-ray spectrum of Mrk 421 hint at extragalactic absorption and that the HEGRA observations of the flaring spectrum of Mrk 501 appear to strongly indicate extragalactic absorption. We also discuss the determination of the y-ray opacity at higher redshifts, following the treatment of Salamon and Stecker. We give a predicted spectrum, with absorption included for PKS 2155-304. This XBL lies at a redshift of 0.12, the highest redshift source yet observed at an energy above 0.3 TeV. This source should have its spectrum steepened by approx. 1 in its spectral index between approx. 0.3 and approx. 3 TeV and should show an absorption cutoff above approx. 6 TeV.

Stecker, F. W.

1998-01-01

43

Heating of the intergalactic medium due to structure formation  

E-print Network

We estimate the heating of the intergalactic medium due to shocks arising from structure formation. Heating of the gas outside the collapsed regions, with small overdensities (${n_b \\over {\\bar n_b}}\\ll 200$) is considered here, with the aid of Zel'dovich approximation. We estimate the equation of state of this gas, relating the density with its temperature, and its evolution in time, considering the shock heating due to one-$\\sigma$ density peaks as being the most dominant. We also estimate the mass fraction of gas above a given temperature as a function of redshift. We find that the baryon fraction above $10^6$ K at $z=0$ is $\\sim 10 %$. We estimate the integrated Sunyaev-Zel'dovich distortion from this gas at present epoch to be of order $10^{-6}$.

Biman Nath; Joseph Silk

2001-07-20

44

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

45

X-ray Observations of the Hot Intergalactic Medium  

E-print Network

A definite prediction from recent N-body/hydro simulations of the structure formation of the universe is the presence of a diffuse intergalactic medium (IGM) in a temperature range of 10^5 - 10^7 K. This hot phase of the IGM may account for most of the baryon content of the universe and may provide unique information on various physical and chemical processes of the structure formation. I review lines of observational evidence for the hot IGM. The topics include the decomposition of the soft X-ray background into point-like and diffuse components, the preliminary spectroscopic data from ASCA for a thermal component, the separation of the Galactic foreground from the extragalactic background, and the detection of individual hot IGM enhancements near rich clusters of galaxies. The results demonstrate the potential of X-ray observations as a powerful tool to study the large-scale structure of the universe.

Q. Daniel Wang

1997-10-14

46

Intergalactic Dust and the Darkness of the Night Sky  

NASA Astrophysics Data System (ADS)

The intensity of the extragalactic background light (EBL) at optical wavelengths is determined to order of magnitude by the age of the Universe, and reduced by a factor of two due to cosmic expansion. Observations have now attained sufficient precision that we can begin to assess the importance of other factors as well. One of these is absorption in the intergalactic medium, originally proposed by de Cheseaux and Olbers as the entire explanation for the darkness of the night sky. While this explanation fails in a bolometric sense, it does play a role in the spectral sense since dust shifts much of the light from distant galaxies into the infrared. We quantify this effect and show that it reduces the intensity of the optical EBL further by one or two percent. Thus, while Olbers and de Cheseaux had it wrong, they were not quite as wrong as commonly supposed.

Prins, Nathan; Overduin, J.; Strobach, E. J.

2014-01-01

47

Whimex: Exploring The High Temperature Intergalactic Medium In This Decade  

NASA Astrophysics Data System (ADS)

Observations of the WHIM strongly indicate that a large percentage of the baryons in the Universe reside in a hot phase, ionized beyond the reach of ultraviolet observatories like FUSE and HST. Chandra and XMM are giving us tantalizing indications that a sufficiently powerful soft x-ray spectrograph could study these gasses in detail. The WARM Hot Intergalactic Medium Explorer is a response to that need. This presentation will explain how the WHIMex team was able to propose an x-ray spectrograph with up to 500 square centimeters of collecting area and spectral resolution of 4000 within the size and cost constraints of the Explorer program. We will present the design of WHIMex and show how the high collecting area and high resolution can enable detection of OVII and OVIII features along the lines of sight to AGNS's as distant z=0.5 and start to better constrain the models of the WHIM.

Cash, Webster C., Jr.; Science, WHIMex; Instrument Teams

2011-05-01

48

Molecular gas in the intergalactic medium of Stephan's Quintet  

E-print Network

Stephan's Quintet (SQ) is a Hickson Compact Group well known for its complex dynamical and star formation history and its rich intergalactic medium (IGM). In order to study the extent, origin and fate of the intergalactic molecular gas and its relation to the formation of stars outside galaxies and Tidal Dwarf Galaxies (TDGs), we mapped with the IRAM 30m antenna carbon monoxide (CO) towards several regions of the IGM in SQ. In two star forming regions (SQ A and B), situated in very different environments, we detected unusually large amounts of molecular gas ($3.1 \\times 10^9$ \\msun and $7 \\times 10^8$ \\msun, respectively), covering an extended area (between 15 and 25 kpc). In both regions the CO clouds have different properties and may be of a distinct nature. The integrated CO line of SQ A is in particular much wider than in SQ B. Its CO spectrum shows emission at two velocities (6000 and 6700 \\kms), coincident with two HI lines, with the stronger emission at 6000 \\kms being very smoothly distributed without a distinct peak in the starburst region. In SQ B the CO emission coincides with that of tracers of star formation (\\halpha, near-infrared 15 $\\mu$m and radio continuum). The CO peak lies close to the HI peak towards a steep HI gradient. This is indicating that the molecular gas is forming in-situ, with subsequent star formation taking place. The star forming region at SQ B is the object in SQ that most resembles a TDG.

Ute Lisenfeld; Stephane Leon; Jonathan Braine; Pierre-Alain Duc; Vassilis Charmandaris; Elias Brinks

2002-10-01

49

Search for emission from warm-hot intergalactic medium  

NASA Astrophysics Data System (ADS)

About half of the baryons in the local Universe are not yet observed and are thought to reside in the intergalactic medium at temperatures of 0.1-10 million K and densities of 10-6 -10-4 cm-3 . This is called warm-hot intergalactic medium (WHIM). In this paper, we summarize search for emission from the WHIM, and show prospects with future instruments. Using XIS instrument onboard Suzaku, we searched for redshifted OVII and OVIII WHIM emission lines, in cluster outskirts and superclusters: Shapley supercluster, Sculptor supercluster, A2218, A1413, A2142, A2052, and the Coma cluster. The chance for detecting a signal was estimated to be sufficient to motivate our search, given the relatively high density and high temperature expected for the WHIM in these regions. We did not detect the significant emission, but obtained upper limits in OVII and OVIII emission intensities for these clusters and superclusters. The density of the WHIM was constrained based on the upper limits, which is 200-300 times mean baryon density of the Universe. Future instruments such as microcalorimeters have much higher sensitivity for weak lines. In particular a combination of a microcalorimeter and large grasp (effective area times field of view) telescope is ideal for mapping of the WHIM. We created mock spectra that contain the WHIM, cosmic X-ray background and Galactic emission. Here we present our results concerning detectability and expected 3-d maps of the line emitting regions asssociated to the WHIM, with future missions such as EDGE/XENIA.

Takei, Yoh; Ohashi, Takaya; Sato, Kosuke; Mitsuishi, Ikuyuki; Branchini, Enzo; Ursino, Eugenio; Corsi, Alessandra

50

Quasar spectroscopy in UV and X-ray- probing the intergalactic medium using helium and oxygen  

E-print Network

We employ ultraviolet (UV) and X-ray quasar spectroscopy to study the physical state of the Intergalactic Medium (IGM). First, we quantify the possibility of measuring the temperature of moderately over-dense regions of ...

Gong, Donglai, 1977-

2004-01-01

51

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.

52

A Study of the Reionization History of Intergalactic Helium with FUSE and the Very Large Telescope  

NASA Astrophysics Data System (ADS)

We obtained high-resolution Far Ultraviolet Spectroscopic Explorer (FUSE; R~20,000) and Very Large Telescope (VLT; R~45,000) spectra of the quasar HE 2347-4342 in order to study the properties of the intergalactic medium between redshifts z=2.0 and 2.9. The high-quality optical spectrum allows us to identify approximately 850 H I absorption lines with column densities between N~5×1011 and 1018 cm-2. The reprocessed FUSE spectrum extends the wavelength coverage of the He II absorption down to an observed wavelength of 920 Å. Source flux is detected to rest-frame wavelengths as short as ~237 Å. Approximately 1400 He II absorption lines are identified, including 917 He II Ly? systems and some of their He II Ly?, Ly?, and Ly? counterparts. The ionization structure of He II is complex, with approximately 90 absorption lines that are not detected in the hydrogen spectrum. These features may represent the effect of soft ionizing sources. The ratio ?=N(HeII)/N(HI) varies approximately from unity to more than a thousand, with a median value of 62 and a distribution consistent with the intrinsic spectral indexes of quasars. This provides evidence that the dominant ionizing field is from the accumulated quasar radiation, with contributions from other soft sources such as star-forming regions and obscured active galactic nuclei, which do not ionize helium. We find an evolution in ? toward smaller values at lower redshift, with the gradual disappearance of soft components. At redshifts z>2.7, the large but finite increase in the He II opacity, ?=5+/-1, suggests that we are viewing the end stages of a reionization process that began at an earlier epoch. Fits of the absorption profiles of unblended lines indicate comparable velocities between hydrogen and He+ ions. For line widths bHe+=?bH, we find ?=0.95+/-0.12, indicating a velocity field in the intergalactic medium dominated by turbulence. At hydrogen column densities N<3×1012 cm-2, the number of forest lines shows a significant deficit relative to a power law and becomes negligible below N=1011 cm-2. Based on observations made for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission; Ultraviolet-Visual Echelle Spectrograph observations performed at the European Southern Observatory, Paranal, Chile, within the program 68.A-0230 and observations with the NASA/ESA Hubble Space Telescope.

Zheng, W.; Kriss, G. A.; Deharveng, J.-M.; Dixon, W. V.; Kruk, J. W.; Shull, J. M.; Giroux, M. L.; Morton, D. C.; Williger, G. M.; Friedman, S. D.; Moos, H. W.

2004-04-01

53

Abundant molecular gas in the intergalactic medium of Stephan's Quintet  

E-print Network

Stephan's Quintet (SQ) is a system consisting of at least four interacting galaxies which is well known for its complex dynamical and star formation history. It possesses a rich intergalactic medium (IGM), where hydrogen clouds, both atomic and molecular, associated with two starbursts (refered to as SQ A and B) have been found. In order to study the extent, origin and fate of the intergalactic molecular gas and its relation to the formation of stars outside galaxies and Tidal Dwarf Galaxies (TDGs), we mapped with the IRAM 30m antenna the carbon monoxide (CO) towards several regions of the IGM in SQ. In both SQ A and B, we detected unusually large amounts of molecular gas (3.1 times 10^9 msun and 7 times 10^8 msun, respectively). In contrast, no significant CO detection was achieved towards HII regions south of the pair NGC 7318a/b despite their high H alpha luminosities. The molecular gas is very extended in both SQ A and SQ B, over areas of between 15 and 25 kpc. The CO clouds seem to have otherwise different properties and may be of a different nature. The integrated CO line of SQ A is in particular much wider than in SQ B. Its CO spectrum shows emission at two velocities (6000 and 6700 km s^{-1}) that are coincident with two HI lines. The strongest emission at 6000 km s^{-1} is however spatially offset from the HI emission and situated on a ridge south-east of the starburst region. In SQ B the CO emission coincides with that of tracers of star formation (halpha, 15 mu m and radio continuum). The CO peak lies slightly offset from the HI peak towards a steep HI gradient. This is indicating that the molecular gas is forming in-situ, possibly in a region of compressed HI, with subsequent star formation. The star forming region at SQ B is the object in SQ that most resembles a TDG.

Ute Lisenfeld; Jonathan Braine; Pierre-Alain Duc; Stephane Leon; Vassilis Charmandaris; Elias Brinks

2002-08-28

54

Effects of AGN feedback in galaxy groups and Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The combination of Cosmological numerical simulations and semi-analytical models of galaxy formation is a very appropriate method to study how different phenomena influence the galaxy and galaxy cluster formation. The main advantage of this combination consists in the fact that N-body simulations do not need to be rerun every time a change in the assumptions about baryonic processes is made since these are included in the semi-analytical models which run on the final N-Body simulation output. The Semi-analytic model takes into account radiative cooling of gas, stellar formation and different types of SN contribution, which eject energy and metals to the interstellar medium, allowing the chemical enrichment of the intergalactic medium. In this project we use the semi-analytic hybrid model by Cora (2006, MNRAS, 368, 1540) and implement the AGN feedback, in two modes, the QSO mode (which takes into account mergers and galactic disk instabilities), and the Radio mode, which modifies the cooling in the galaxies These two processes allow to suppress the super flows in the hybrid model, and allows the study of QSOs in galaxy groups. This new implementation opens different possibles studies including the QSO luminosity function, the anti-hierarchical evolution of Mass Function, the BH mass and bulge mass relation, Color-Magnitude diagrams, TF relation, the galaxy luminosity function, the effects of AGN in neighbor galaxies and the behavior of QSOs in the sub-millimeter window.

Lagos, C.; Padilla, N.; Cora, S.

2009-05-01

55

Galaxy formation in an intergalactic medium dominated by explosions  

NASA Technical Reports Server (NTRS)

The evolution of galaxies in an intergalactic medium dominated by explosions of star systems is considered analogously to star formation by nonlinearly interacting processes in the interstellar medium. Conditions for the existence of a hydrodynamic instability by which galaxy formation leads to more galaxy formation due to the propagation of the energy released at the death of massive stars are examined, and it is shown that such an explosive amplification is possible at redshifts less than about 5 and stellar system masses between 10 to the 8th and 10 to the 12th solar masses. Explosions before a redshift of about 5 are found to lead primarily to the formation of massive stars rather than galaxies, while those at a redshift close to 5 will result in objects of normal galactic scale. The model also predicts a dusty interstellar medium preventing the detection of objects of redshift greater than 3, numbers and luminosities of protogalaxies comparable to present observations, unvirialized groups of galaxies lying on two-dimensional surfaces, and a significant number of black holes in the mass range 1000-10,000 solar masses.

Ostriker, J. P.; Cowie, L. L.

1981-01-01

56

Faraday Rotation Measure due to the Intergalactic Magnetic Field  

E-print Network

Studying the nature and origin of the intergalactic magnetic field (IGMF) is an outstanding problem of cosmology. Measuring Faraday rotation would be a promising method to explore the IGMF in the large-scale structure (LSS) of the universe. We investigated the Faraday rotation measure (RM) due to the IGMF in filaments of galaxies using simulations for cosmological structure formation. We employed a model IGMF based on turbulence dynamo in the LSS of the universe; it has an average strength of $ \\sim 10$ nG and a coherence length of several $\\times\\ 100\\ h^{-1}$ kpc in filaments. With the coherence length smaller than path length, the inducement of RM would be a random walk process, and we found that the resultant RM is dominantly contributed by the density peak along line of sight. The rms of RM through filaments at the present universe was predicted to be $\\sim 1\\ {\\rm rad\\ m^{-2}}$. In addition, we predicted that the probability distribution function of $|{\\rm RM}|$ through filaments follows the log-normal ...

Akahori, Takuya

2010-01-01

57

Metal abundances in the high-redshift intergalactic medium  

NASA Astrophysics Data System (ADS)

Twenty years of high-resolution spectroscopy at the 8-10 m class telescopes have drastically expanded our view of the gas-phase metallicity in the zgtrsim 2 universe. This contribution briefly summarizes how these studies reveal a widespread metal pollution in the intergalactic medium with a median abundance [C/H]˜ -3.5 at z ˜ 3 that is increasing by a factor of ˜ 2-3 from z˜ 4.3 to z˜ 2.4. At the higher densities that are typical of galactic halos, observations uncover a metallicity spread of five orders of magnitude in Lyman limit systems, ranging from super-solar ([M/H] ˜ +0.7) to pristine ([M/H] ? -4) gas clouds. Finally, the neutral damped Lyalpha systems are enriched to a median metallicity of [M/H] ˜ -1.5 that slowly declines with redshift up to z˜ 4.5, at which point it appears to more rapidly evolve as one approaches the end of reionization.

Fumagalli, Michele

58

The evolution of a pre-heated Intergalactic Medium  

E-print Network

We analyse the evolution of the Intergalactic Medium (IGM) by means of an extended set of large box size hydrodynamical simulations which include pre-heating. We focus on the properties of the z~2 Lyman-alpha forest and on the population of clusters and groups of galaxies at z=0. We investigate the distribution of voids in the Lyman-alpha flux and the entropy-temperature relation of galaxy groups, comparing the simulation results to recent data from high-resolution quasar spectra and from X-ray observations. Pre-heating is included through a simple phenomenological prescription, in which at z=4 the entropy of all gas particles, whose overdensity exceeds a threshold value delta_h is increased to a minimum value K_fl. While the entropy level observed in the central regions of galaxy groups requires a fairly strong pre-heating, with K_fl>100 keV cm^2, the void statistics of the Lyman-alpha forest impose that this pre-heating should take place only in relatively high-density regions, in order not to destroy the cold filaments that give rise to the forest. We conclude that any injection of non-gravitational energy in the diffuse baryons should avoid low-density regions at high redshift and/or take place at relatively low redshift.

S. Borgani; M. Viel

2008-10-18

59

Exploring the intergalactic medium with VLT/UVES  

E-print Network

The remarkable efficiency of the UVES spectrograph at the VLT has made it possible to push high-resolution, high-S/N ground observations of the Ly-a forest down to z~1.5, gaining new insight into the physical conditions of the intergalactic medium and its evolution over more than 90% of the cosmic time. The universal expansion, the UV ionizing background and the gravitational condensation of structures are the driving factors shaping the number density and the column density distribution of the absorbers. A (limited) contribution of UV photons produced by galaxies is found to be important to reproduce the observed evolutionary pattern at very high and low redshift. The Lyman forest contains most of the baryons, at least at z>1.5, and acts as a reservoir for galaxy formation. The typical Doppler parameter at a fixed column density is measured to slightly increase with decreasing redshift, but the inferred temperature at the mean density is increasing with redshift. The signatures of HeII reionization and feedback from the formation of galactic structures have possibly been detected in the Lyman forest.

S. Cristiani; S. Bianchi; S. D'Odorico; T. -S. Kim

2001-12-12

60

Heating of Intergalactic Gas and Cluster Scaling Relations  

E-print Network

X-ray observations of galaxy groups and clusters are inconsistent with the predictions of the simplest hierarchical clustering models, wherein non-baryonic and baryonic components are assembled together under the sole influence of gravity. These departures are in the sense that the intergalactic medium is hotter and more extended than expected, and become increasingly strong for less massive systems. I model these effects by constructing baseline sequences of hydrostatic polytropic models normalized to observations of high-temperature clusters and numerical simulations, and then transforming them by adding proscribed amounts of heat per particle at the cluster center. I present sequences with a universal value of this heating parameter that simultaneously reproduce recently published observed (gas and total gravitational) mass-temperature and entropy-temperature relations. The required amount of energy injection is consistent with constraints on the number of supernovae needed to account for observed intracluster silicon abundances, provided that energy injection is centrally concentrated. I argue that most of the heating occurred during or after the assembly of the cluster, and not exclusively in pre-collapse proto-cluster fragments.

Michael Loewenstein

1999-10-14

61

Constraints on the intergalactic transport of cosmic rays  

SciTech Connect

Motivated by recent experimental proposals to search for extragalactic cosmic rays (including antimatter from distant galaxies), we study particle propagation through the intergalactic medium (IGM). We first use estimates of the magnetic field strength between galaxies to constrain the mean free path for diffusion of particles through the IGM. We then develop a simple analytic model to describe the diffusion of cosmic rays. Given the current age of galaxies, our results indicate that, in reasonable models, a completely negligible number of particles can enter our Galaxy from distances greater than {approximately}100Mpc for relatively low energies (E{lt}10{sup 6}GeVnucleon{sup {minus}1}). We also find that particle destruction in galaxies along the diffusion path produces an exponential suppression of the possible flux of extragalactic cosmic rays. Finally, we use gamma-ray constraints to argue that the distance to any hypothetical domains of antimatter must be roughly comparable to the horizon scale. {copyright} {ital 1997} {ital The American Astronomical Society}

Adams, F.C.; Freese, K.; Laughlin, G.; Schwadron, N.; Tarle, G. [Physics Department, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)] [Physics Department, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)

1997-12-01

62

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

63

Can the intergalactic medium cause a rapid drop in Ly? emission at z > 6?  

NASA Astrophysics Data System (ADS)

The large cross-section of the Ly? line makes it a sensitive probe of the ionization state of the intergalactic medium (IGM). Here, we present the most complete study to date of the IGM Ly? opacity, and its application to the redshift evolution of the `Ly? fraction', i.e. the fraction of colour-selected galaxies with a detectable Ly? emission line. We use a tiered approach, which combines large-scale seminumeric simulations of reionization with moderate-scale hydrodynamic simulations of the ionized IGM. This allows us to simultaneously account for evolution in both: (i) the opacity from an incomplete (patchy) reionization, parametrized by the filling factor of ionized regions, QH II; and (ii) the opacity from self-shielded systems in the ionized IGM, parametrized by the average photoionization rate inside H II regions, H II. In contrast to recent empirical models, attenuation from patchy reionization has a unimodal distribution along different sightlines, while attenuation from self-shielded systems is more bimodal. We quantify the average IGM transmission in our (QH II, H II) parameter space, which can easily be used to interpret new data sets. Our new, improved models highly disfavour an evolution in H II as the sole driver of a large change in IGM opacity. Using current observations, we predict that the Ly? fraction cannot drop by more than a factor of ?2 with IGM attenuation alone, even for H II filling factors as low as QH II ? 0.1. Larger changes in the Ly? fraction could result from a co-evolution with galaxy properties. Marginalizing over H II, we find that current observations constrain QH II(z ? 7) ? 0.6, at a 68 per cent confidence level (CL). However, all of our parameter space is consistent with observations at 95 per cent CL, highlighting the need for larger observational samples at z ? 6.

Mesinger, Andrei; Aykutalp, Aycin; Vanzella, Eros; Pentericci, Laura; Ferrara, Andrea; Dijkstra, Mark

2015-01-01

64

Multifrequency survey of the intergalactic cloud in the M96 group  

NASA Technical Reports Server (NTRS)

The intergalactic cloud of neutral hydrogen in the M96 group are examined for signs of emission over a wide range of frequencies, from radio waves to X rays. Past or present stellar activity in the gas might have been expected to produce detectable visual infrared, CO, OH, or radio recombination-line emission. None was detected. The limits are used to study physical conditions in the intergalactic gas. In particular, B and V band limits on starlight and IRAS limits on the presence of dust strongly constrain the presence of stars or stellar by-products. However, given the uncertainties about physical conditions in the intergalactic environment, it is difficult to rule out entirely the presence of stellar-processed materials. Results of neutral hydrogen mapping from a large-scale survey of the intergalactic cloud and surrounding region are also presented. These observations confirm that the gas is confined to a large ringlike structure. The simplest interpretation remains that the intergalactic gas in Leo is primordial.

Schneider, Stephen E.; Skrutskie, M. F.; Hacking, Perry B.; Young, Judith S.; Dickman, Robert L.

1989-01-01

65

Multifrequency survey of the intergalactic cloud in the M96 group  

SciTech Connect

The intergalactic cloud of neutral hydrogen in the M96 group are examined for signs of emission over a wide range of frequencies, from radio waves to X rays. Past or present stellar activity in the gas might have been expected to produce detectable visual infrared, CO, OH, or radio recombination-line emission. None was detected. The limits are used to study physical conditions in the intergalactic gas. In particular, B and V band limits on starlight and IRAS limits on the presence of dust strongly constrain the presence of stars or stellar by-products. However, given the uncertainties about physical conditions in the intergalactic environment, it is difficult to rule out entirely the presence of stellar-processed materials. Results of neutral hydrogen mapping from a large-scale survey of the intergalactic cloud and surrounding region are also presented. These observations confirm that the gas is confined to a large ringlike structure. The simplest interpretation remains that the intergalactic gas in Leo is primordial. 36 references.

Schneider, S.E.; Skrutskie, M.F.; Hacking, P.B.; Young, J.S.; Dickman, R.L.

1989-03-01

66

Metallicity of the intergalactic medium using pixel statistics: III. Silicon  

E-print Network

(Modified) We study the abundance of silicon in the intergalactic medium by analyzing the statistics of SiIV, CIV, and HI pixel optical depths in a sample of 19 high-quality quasar absorption spectra spanning redshifts z ~ 2 - 4, which we compare to realistic spectra drawn from a hydrodynamical simulation. We find that silicon is highly overabundant relative to carbon and that the scatter in Si/C is much smaller than that in C/H, implying a common origin for Si and C. The inferred [Si/C] depends upon the shape of the UV background (UVB) (harder backgrounds leading to higher [Si/C]), ranging from [Si/C] ~ 1.5 for a quasar-only UVB, to [Si/C] ~ 0.25 for a UVB including both galaxies and an artificial softening. For our fiducial UVB, which includes both quasars and galaxies, we find [Si/C]=0.77 +/- 0.05, with a possible systematic error of ~ 0.1 dex. There is no evidence for evolution in [Si/C] and the data are inconsistent with previous claims of a sharp change in the SiIV/CIV ratio (or the UVB) at z ~ 3. Comparisons with low-metallicity halo stars and nucleosynthetic yields suggest that either our fiducial UVB is too hard or that supermassive Pop III stars might have to be included. The inferred [Si/C] corresponds to a contribution to the cosmic Si abundance of [Si/H] = -2.0, a significant fraction of all Si production expected by z ~ 3.

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

2004-01-13

67

The Search for Intergalactic Hydrogen Clouds in Voids  

E-print Network

I present the results of a search for intergalactic hydrogen clouds in voids. Clouds are detected by their HI LyA absorption lines in the HST spectra of low-redshift AGN. The parameter with which the environments of clouds are characterized is the tidal field, which places a lower limit on the cloud mass-density which is dynamically stable against disruption. Galaxy redshift catalogs are used to sum the tidal fields along the lines of sight, sorting clouds according to tidal field upper, or lower limits. The analytical methodology employed is designed to detect gas clouds whose expansion following reionization is restrained by dark matter perturbations. End-products are the cloud equivalent width distribution functions (EWDF) of catalogs formed by sorting clouds according to various tidal field upper, or lower limits. Cumulative EWDFs are steep in voids (S ~ -1.5 \\pm 0.2), but flatter in high tidal field zones (S ~ -0.5 \\pm 0.1). Most probable cloud Doppler parameters are ~30 km/s in voids and ~60 km/s in proximity to galaxies. In voids, the cumulative line density at low EW (~ 15 mA) is ~ 500 per unit redshift. The void filling factor is found to be 0.87 void EWDF is remarkably uniform over this volume, with a possible tendency for more massive clouds to be in void centers. The size and nature of the void cloud population suggested by this study is completely unanticipated by the results of published 3-D simulations, which predict that most clouds are in filamentary structures around galaxy concentrations, and that very few observable absorbers would lie in voids. Strategies for modeling this population are briefly discussed.

C. V. Manning

2002-04-22

68

Probing Weak Intergalactic Absorption with Flaring Blazar Spectra  

NASA Astrophysics Data System (ADS)

We propose to exploit the flaring states of high- and unknown-redshift blazars to obtain very high S/N > 25 COS spectra in order to study details of the local intergalactic medium {IGM} not accessible for study using the plethora of lower S/N data being obtained. Only with very high S/N spectra is it possible to detect the weakest Ly alpha and metal lines wherein may lie a substantial portion of the cosmic baryons. The numbers of weak OVI absorbers can discriminate between collisionally ionized and photoionized models, as well as determine which of several galactic outflow models best matches the IGM metal enrichment. Most importantly, high S/N spectra plus the featureless UV power-law continuum of blazars facilitates the detection of broad, shallow absorbers ["broad Ly alpha" {BLA} and broad OVI-only absorbers] which uniquely probe the T = 3 x 10^5 - 3 x 10^6 K range in the IGM where many cosmic baryons are predicted to be "hiding."In addition, these same spectra will be used to obtain lower limits on, or estimates of, the redshift for any featureless blazars observed using the foreground Ly-alpha forest absorbers. In some cases weak Lyman alpha emission may also be detected, as was recently discovered for a few well-known low-redshift BL Lac objects using COS spectra. We request up to three *non-disruptive ToOs* to carry out this program in Cycle 19. Ground-based monitoring will select objects flaring to V 13.5 mag for HST observations, out of a set of about 30 monitored blazars.

Stocke, John

2011-10-01

69

Probing Weak Intergalactic Absorption with Flaring Blazar Spectra 2  

NASA Astrophysics Data System (ADS)

We propose to exploit the flaring states of high- and unknown-redshift blazars to obtain very high S/N > 25 COS spectra in order to study details of the local intergalactic medium {IGM} not accessible for study using the plethora of lower S/N data being obtained. Only with very high S/N spectra is it possible to detect the weakest Ly alpha and metal lines wherein may lie a substantial portion of the cosmic baryons. The numbers of weak OVI absorbers can discriminate between collisionally ionized and photoionized models, as well as determine which of several galactic outflow models best matches the IGM metal enrichment. Most importantly, high S/N spectra plus the featureless UV power-law continuum of blazars facilitates the detection of broad, shallow absorbers ["broad Ly alpha" {BLA} and broad OVI-only absorbers] which uniquely probe the T = 3 x 10^5 - 3 x 10^6 K range in the IGM where many cosmic baryons are predicted to be "hiding."In addition, these same spectra will be used to obtain lower limits on, or estimates of, the redshift for any featureless blazars observed using the foreground Ly-alpha forest absorbers. In some cases weak Lyman alpha emission may also be detected, as was recently discovered for a few well-known low-redshift BL Lac objects using COS spectra. We request up to three *non-disruptive ToOs* to carry out this program in Cycle 19. Ground-based monitoring will select objects flaring to V 13.5 mag for HST observations, out of a set of about 200 monitored blazars.

Stocke, John

2012-10-01

70

Evolution of the intergalactic medium - What happened during the epoch z = 3-10?  

NASA Technical Reports Server (NTRS)

An attempt is made to model consistently the thermal and dynamic history of the intergalactic medium (IGM) from the era of reheating (z = 10-5) to the present, and to provide a unified explanation for the origin of ordinary galaxies, blue compact objects, and Lyman-alpha clouds. The evolution of the intergalactic gas is analyzed, treating the IGM as perfectly homogeneous at every epoch and taking into account radiative and Compton cooling, adiabatic cooling, shock heating, and heating produced by the diffuse UV flux. It is suggested that the IGM must have been heated to higher than a 10 to the 6th K by shock heasting caused either by explosions of pregalactic objects or expanding voids. The formation of intergalactic clouds by fragmentation of the resulting shells and the subsequent collapse of the shells to form galaxies are studied. An attempt is made to determine model parameters on the basis of an analysis of Lyman-alpha absorption lines.

Ikeuchi, S.; Ostriker, J. P.

1986-01-01

71

X-ray studies of galactic and intergalactic gas in the Pegasus I cluster  

NASA Astrophysics Data System (ADS)

Observations of Pegasus I with the Einstein Observatory IPC reveal hot gas in a low-density intergalactic medium and in a galactic medium within each of the dominant elliptical galaxies NGC 7619 and NGC 7626. The galaxies have X-ray luminosities of 8 and 3×1041ergs s-1 respectively, temperatures of ?107K, mean gas densities of ?10-3cm-3 and gas masses of ?1010M_sun;. The intergalactic gas has a luminosity of 1×1042ergs s-1, a density of ?2×10-4cm-3, a mass of ?4×1011M_sun;, and a temperature of ?107K.

Canizares, C. R.; Donahue, M. E.; Trinchieri, G.; Stewart, G. C.; McGlynn, T. A.

1986-05-01

72

Evolution of Structure in the Intergalactic Medium and the Nature of the Ly alpha Forest  

Microsoft Academic Search

We have performed a detailed statistical study of the evolution of structure in a photoionized intergalactic medium (IGM) using analytical simulations to extend the calculation into the mildly nonlinear density regime found to prevail at z = 3. Our work is based on a simple fundamental conjecture: that the probability distribution function of the density of baryonic diffuse matter in

Hongguang Bi; Arthur F. Davidsen

1997-01-01

73

Redshifted intergalactic {sup 3}He{sup +} 8.7 GHz hyperfine absorption  

SciTech Connect

Motivated by recent interest in redshifted 21 cm emission of intergalactic hydrogen, we investigate the 8.7 GHz {sup 2}S{sub 1/2} F=0-1 hyperfine transition of {sup 3}He{sup +}. While the primordial abundance of {sup 3}He relative to hydrogen is 10{sup -5}, the hyperfine spontaneous decay rate is 680 times larger. Furthermore, the antenna temperature is much lower at the frequencies relevant for the {sup 3}He{sup +} transition compared to that of z>6 21 cm emission. We find that the spin temperature of this 8.7 GHz line in the intergalactic medium is approximately the cosmic microwave background temperature, such that this transition is best observed in absorption against high-redshift, radio-bright quasars. We show that intergalactic 8.7 GHz absorption is a promising, unsaturated observable of the ionization history of intergalactic helium (for which He II{yields}He III reionization is believed to complete at z{approx}3) and of the primordial {sup 3}He abundance. Instruments must reach {approx}1 {mu}Jy RMS noise in bands of 1 MHz on a 1 Jy source to directly resolve this absorption. However, in combination with H i Ly{alpha} forest measurements, an instrument can statistically detect this absorption from z>3 with 30 {mu}Jy RMS noise in 0.1 MHz spectral bands over 100 MHz, which may be within the reach of present instruments.

McQuinn, Matthew; Switzer, Eric R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States); Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois, 60637 (United States)

2009-09-15

74

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

75

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

76

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

77

The Carbon Content of Intergalactic Gas at Z=4.25 and Its Evolution toward Z=2.4  

E-print Network

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 ...

Simcoe, Robert A.

78

Massive Star Formation Triggered by Collision between Galactic and Accreted Intergalactic Clouds  

NASA Astrophysics Data System (ADS)

We present mapping observations of molecular lines 12CO (2-1), 12CO (3-2), 13CO (2-1), and 13CO (3-2) toward the massive star-forming region IRAS 04000+5052 that suggest kinematics consistent with cloud-cloud collision and a possible unusual abundance ratio of carbon isotopes. Together with the previous spectroscopic study that shows an extreme deficiency in heavy elements in the surrounding nebulosity-suggestive of primordial nature-we propose that the cloud material is of intergalactic origin and that the young star cluster in IRAS 04000+5052 is the consequence of triggered star formation due to the collision of a Galactic cloud with accreted intergalactic material.

Wang, Jun-Jie; Chen, Wen-Ping; Miller, Martin; Qin, Sheng-Li; Wu, Yue-Fang

2004-10-01

79

The exchange of metals between galaxies and the intergalactic medium at high redshift.  

NASA Astrophysics Data System (ADS)

I discus several important issues in the exchange of metals between galaxies and the intergalactic medium at high redshift. The ejection of metals from galaxies appears to be more efficient at high-redshift than today, as can be understood not only because of the smaller gravitational potential wells of galaxies, but also because of their more compact sizes, spatial distribution, and the overall expansion of the universe. By z ? 2, intergalactic enrichment at appears to be concentrated around large galaxies and this is likely due primarily due to metals from similarly-biased higher-redhishift sources, although ongoing studies using pairs of quasar sight lines are necessary to settle this issue definitively. Finally, I discuss the mixing of metals, which occurs through a turbulent cascade similar to the Kolmogorov energy cascade. Our direct simulations of this process have yielded sub-grid models that can track the formation history of metal-free stars.

Scannapieco, E.

80

X-ray studies of galactic and intergalactic gas in the Pegasus I cluster  

NASA Technical Reports Server (NTRS)

Einstein Observatory IPC observations of Pegasus I show hot gas in a low density intergalactic medium as well as in a galactic medium within each of the dominant elliptical galaxies, NGC 7619 and NGC 7626. The short central cooling times inferred, of 100 million years or less, suggest that the galaxies contain cooling flows of about 1 solar mass/yr. The intergalactic gas, which is about 5 times less dense than in the least dense of the known Abell clusters, is incapable of stripping the hot gas from the elliptical galaxies or the neutral gas from the spirals. The gas around NGC 7619 appears to be influencing one of the radio lobes of NGC 7626.

Canizares, C. R.; Donahue, M. E.; Trinchieri, G.; Stewart, G. C.; Mcglynn, T. A.

1986-01-01

81

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

82

Constraints on the Sunyaev-Zel'dovich signal from the warm-hot intergalactic medium from WMAP and SPT data  

NASA Astrophysics Data System (ADS)

The fraction of ionized gas in the warm-hot intergalactic medium induces temperature anisotropies on the cosmic microwave background similar to those of clusters of galaxies. The Sunyaev-Zel'dovich (SZ) anisotropies due to these low-density, weakly non-linear, baryon filaments cannot be distinguished from that of clusters using frequency information, but they can be separated since their angular scales are very different. To determine the relative contribution of the WHIM SZ signal to the radiation power spectrum of temperature anisotropies, we explore the parameter space of the concordance ? cold dark matter model using Monte Carlo Markov chains and the Wilkinson Microwave Anisotropy Probe 7 yr and South Pole Telescope data. We find marginal evidence of a contribution by diffuse gas, with amplitudes of AWHIM = 10-20 ?K2, but the results are also compatible with a null contribution from the WHIM, allowing us to set an upper limit of AWHIM < 43 ?K2 (95.4 per cent CL). The signal produced by galaxy clusters remains at ACL = 4.5 ?K2, a value similar to what is obtained when no WHIM is included. From the measured WHIM amplitude, we constrain the temperature-density phase diagram of the diffuse gas, and find it to be compatible with numerical simulations. The corresponding baryon fraction in the WHIM varies from 0.43 to 0.47, depending on model parameters. The forthcoming Planck data could set tighter constraints on the temperature-density relation.

Génova-Santos, Ricardo; Suárez-Velásquez, I.; Atrio-Barandela, F.; Mücket, J. P.

2013-07-01

83

ON LYMAN-LIMIT SYSTEMS AND THE EVOLUTION OF THE INTERGALACTIC IONIZING BACKGROUND  

SciTech Connect

We study the properties of self-shielding intergalactic absorption systems and their implications for the ionizing background. We find that cosmological simulations post-processed with detailed radiative transfer calculations generally are able to reproduce the observed abundance of Lyman-limit systems, and we highlight possible discrepancies between the observations and simulations. This comparison tests cosmological simulations at overdensities of {approx}100. Furthermore, we show that the properties of Lyman-limit systems in these simulations, in simple semianalytic arguments, and as suggested by recent observations indicate that a small change in the ionizing emissivity of the sources would have resulted in a much larger change in the amplitude of the intergalactic H I-ionizing background (with this scaling strengthening with increasing redshift). This strong scaling could explain the rapid evolution in the Ly{alpha} forest transmission observed at z Almost-Equal-To 6. Our calculations agree with the suggestion of simpler models that the comoving ionizing emissivity was constant or even increasing from z = 3 to 6. Our calculations also provide a more rigorous estimate than in previous studies for the clumping factor of intergalactic gas after reionization, which we estimate was Almost-Equal-To 2-3 at z = 6.

McQuinn, Matthew; Faucher-Giguere, Claude-Andre [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Peng Oh, S., E-mail: mmcquinn@berkeley.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2011-12-10

84

Intergalactic Gas in Groups of Galaxies: Implications for Dwarf Spheroidal Formation and the Missing Baryons Problem  

NASA Astrophysics Data System (ADS)

Radio galaxies with bent jets are predominantly located in groups and clusters of galaxies. We use bent-double radio sources, under the assumption that their jets are bent by ram pressure, to probe intragroup medium (IGM) gas densities in galaxy groups. This method provides a direct measurement of the intergalactic gas density and allows us to probe intergalactic gas at large radii and in systems whose IGM is too cool to be detected by the current generation of X-ray telescopes. We find gas with densities of 10-3 to 10-4 cm-3 at group radii from 15 to 700 kpc. A rough estimate of the total baryonic mass in intergalactic gas is consistent with the missing baryons being located in the IGM of galaxy groups. The neutral gas will be easily stripped from dwarf galaxies with total masses of 106-107 M sun in the groups studied here. Indications are that intragroup gas densities in less-massive systems like the Local Group should be high enough to strip gas from dwarfs like Leo T and, in combination with tides, produce dwarf spheroidals.

Freeland, E.; Wilcots, E.

2011-09-01

85

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

86

A DETERMINATION OF THE INTERGALACTIC REDSHIFT-DEPENDENT ULTRAVIOLET-OPTICAL-NIR PHOTON DENSITY USING DEEP GALAXY SURVEY DATA AND THE GAMMA-RAY OPACITY OF THE UNIVERSE  

SciTech Connect

We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy surveys. This allows us to obtain an empirical determination of the IBL and to quantify its observationally based uncertainties. Using our results on the IBL, we then place 68% confidence upper and lower limits on the opacity of the universe to {gamma}-rays, free of the theoretical assumptions that were needed for past calculations. We compare our results with measurements of the extragalactic background light and upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope.

Stecker, Floyd W. [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Scully, Sean T., E-mail: Floyd.W.Stecker@nasa.gov, E-mail: malkan@astro.ucla.edu, E-mail: scullyst@jmu.edu [Department of Physics, James Madison University, Harrisonburg, VA 22807 (United States)

2012-12-20

87

On the origin of warps and the role of the intergalactic medium  

NASA Astrophysics Data System (ADS)

There is still no consensus as to what causes galactic discs to become warped. Successful models should account for the frequent occurrence of warps in quite isolated galaxies, their amplitude as well as the observed azimuthal and vertical distributions of the HI layer. Intergalactic accretion flows and intergalactic magnetic fields may bend the outer parts of spiral galaxies. In this paper we consider the viability of these non-gravitational torques to take the gas off the plane. We show that magnetically generated warps are clearly flawed because they would wrap up into a spiral in less than two or three galactic rotations. The inclusion of any magnetic diffusivity to dilute the wrapping effect causes the amplitude of the warp to damp. We also consider the observational consequences of the accretion of an intergalactic plane-parallel flow at infinity. We have computed the amplitude and warp asymmetry in the accretion model, for a disc embedded in a flattened dark matter halo, including self-consistently the contribution of the modes with azimuthal wavenumbers m= 0 and m= 1. Since the m= 0 component, giving a U-shaped profile, is not negligible compared to the m= 1 component, this model predicts quite asymmetric warps, maximum gas displacements on the two sides in the ratio 3 : 2 for the preferred Galactic parameters, and the presence of a fraction ~3.5 per cent of U-shaped warps, at least. The azimuthal dependence of the moment transfer by the ram pressure would produce a strong asymmetry in the thickness of the HI layer and asymmetric density distributions in z, in conflict with observational data for the warp in our Galaxy and in external galaxies. The amount of accretion that is required to explain the Galactic warp would give gas scaleheights in the far outer disc that are too small. We conclude that accretion of a flow with no net angular momentum cannot be the main and only cause of warps.

Sánchez-Salcedo, F. J.

2006-01-01

88

Characterizing the non-equilibrium ionization state of the intergalactic medium  

NASA Astrophysics Data System (ADS)

One of the most common ions used to track metals in the intergalactic medium (IGM) is OVI. Ion species in the IGM are typically assumed to be in ionization equilibrium, but owing to the low density of the plasma they may be significantly out of equilibrium. Divergences from equilibrium would make estimates of the amount and evolution of metals in the IGM incorrect. Using a new software package for building and solving complex chemical networks coupled to cosmological hydrodynamic + N-body simulations, we investigate the non-equilibrium properties of the IGM. In particular, we explore how significantly the ionization structure of the IGM diverges from the equilibrium state as a function of time and physical environment. Motivated by the abundant observational data that probes the intergalactic medium via OVI absorption lines in quasar spectra, we track all ionization states of atomic oxygen alongside those of hydrogen and helium. We use the results of these non-equilibrium simulations to characterize the mass content and ionization properties of the IGM and help interpret current observations made by the Cosmic Origins Spectrograph.

Silvia, Devin W.; O'Shea, Brian W.; Smith, Britton D.; Shull, J. Michael; Turk, Matthew; Reynolds, Daniel

2015-01-01

89

Realistic Multi-ion Absorption Spectra from Simulations of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Observational efforts to form a complete baryon census below a redshift of z ~ 3 have proven to be a difficult undertaking. Simulations suggest that much of this baryonic matter may exist between galaxies at low to moderate densities and temperatures of 105 to 107 K, which is best detected by absorption features in the spectra of distant quasars. Due to the challenges of detecting the warm-hot intergalactic medium (WHIM), single ion studies are insufficient in tracing the properties of the WHIM and multi-ion studies are becoming increasingly important. Using cosmological simulations of the IGM, we investigate the ionization structure using multiple ions, including commonly observed species such as OVI, CIV, and NeVIII. To examine the simulation in a manner similar to observations of the IGM, we created a pipeline for producing synthetic absorption spectra from simulated light rays that mimic spectra acquired by observations. Specifically, we add observational noise and convolve the synthetic spectrum with the line spread function of the Cosmic Origins Spectrograph. We then fit the realistic spectra using an automatic process, to determine the properties of the IGM that the light ray intersects. Using the fitted spectra and the inferred physical properties, we help interpret on-going observational studies of the intergalactic medium and aid in forming a complete baryon census.

Kneibel, Jacob; Silvia, Devin; O'Shea, Brian W.

2015-01-01

90

"Marijuana has been compared to walking a foot off the ground as opposed to the intergalactic voyage produced  

E-print Network

to the intergalactic voyage produced by LSD" (source- unknown) Original LSD experience "In afternoon of 16 April, 1943 of Albert Hofmann at Sandoz) when synthesizing LSD-25) #12;2 First LSD Dosing Experiment "After 40 minutes synthesizing LSD-25) Synesthesia "The guide asked me how I felt and I responded `Good'. As I uttered the word

Squire, Larry R.

91

Spitzer Space Telescope Research Program for Teachers and Students: Using Spitzer data in your classroom with (relatively) simple software  

Microsoft Academic Search

The Spitzer Space Telescope Teacher Program is a collaboration between the Spitzer Science Center and the National Optical Astronomy Observatory. Through the program, twelve teachers were selected to submit observing proposals for time on the Spitzer Space Telescope. The Intergalactic Star Formation in Tidal Dwarf Galaxies of M81 Project was one of those selected and awarded director's discretionary observing time

Theresa E. Roelofsen Moody; J. J. Feldmeier; V. Gorjian; B. Sepulveda; E. Sharma; T. Spuck; C. Weehler

2006-01-01

92

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 angular anisotropy 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, thereby 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 current Fermi data already seem to prefer nonnegligible IGMF values. 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.

2013-01-01

93

A census of H? emitters in the intergalactic medium of the NGC 2865 system  

NASA Astrophysics Data System (ADS)

Tidal debris, which are rich in HI gas and formed in interacting and merging systems, are suitable laboratories to study star formation outside galaxies. Recently, several such systems were observed, which contained many young star forming regions outside the galaxies. In previous works, we have studied young star forming regions outside galaxies in different systems with optical and/or gaseous tidal debris, in order to understand how often they occur and in which type of environments. In this paper, we searched for star forming regions around the galaxy NGC 2865, a shell galaxy that is circled by a ring of HI with a total mass of 1.2 × 109 M?. Using the multi-slit imaging spectroscopy technique with the Gemini telescope, we detected all H? emitting sources in the surroundings of the galaxy NGC 2865, down to a flux limit of 10-18 erg cm-2 s-1 Å-1. With the spectra information and the near and far-ultraviolet flux, we characterize the star formation rates, masses, ages, and metallicities for these HII regions. In total, we found 26 emission-line sources in a 60 × 60 Kpc field centered over the southeastern tail of the HI gas present around the galaxy NGC 2865. Out of the 26 H? emitters, 19 are in the satellite galaxy FGCE 0745, and seven are intergalactic HII regions scattered over the south tail of the HI gas around NGC 2865. We found that the intergalactic HII regions are young (<200 Myr) with stellar masses in the range 4 × 103 M? to 17 × 106 M?. These are found in a region of low HI gas density, where the probability of forming stars is expected to be low. For one of the intergalactic HII regions, we estimated a solar oxygen abundance of 12 + log(O/H) ~ 8.7. We also were able to estimate the metallicity for the satellite galaxy FGCE 0745 to be 12 + log(O/H) ~ 8.0. Given these physical parameters, the intergalactic HII regions are consistent with young star forming regions (or clusters), which are born in situ outside the NGC 2865 galaxy from a pre-enriched gas removed from the host galaxies in a merger event. The relevance of these observations is discussed. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina) - Observing runs: GS-2008A-Q-35.

Urrutia-Viscarra, F.; Arnaboldi, M.; Mendes de Oliveira, C.; Gerhard, O.; Torres-Flores, S.; Carrasco, E. R.; de Mello, D.

2014-09-01

94

Non-equilibrium Ionization State of Warm-Hot Intergalactic Medium  

E-print Network

Time evolution of the ionization state of metals in the cosmic baryons is investigated in a cosmological context without the assumption of ionization equilibrium. We find that a significant fraction of ionized oxygen ions (OVII and OVIII) in the warm-hot intergalactic medium (WHIM) is not in the ionization equilibrium state at a redshift of z~0. We also investigate the effect on the detectability and observables of WHIM as a consequence of such deviation from ionization equilibrium. It is found that the detectability of WHIM is not altered very much both through its emission and absorption signatures, but line ratios between OVII and OVIII are significantly different from those in the ionization equilibrium state.

Kohji Yoshikawa; Shin Sasaki

2006-06-13

95

Spontaneous magnetization of a vacuum in the hot Universe and intergalactic magnetic fields  

NASA Astrophysics Data System (ADS)

We review the spontaneous magnetization of the vacuum of non-Abelian gauge fields at high temperature. The standard model of particles is investigated as a particular example. By using both analytic methods of quantum field theory and gauge field theory on a lattice, we determine the Abelian (chromo)magnetic fields in the restored phase of the model at high temperatures T ? T ew . The fields are stable and temperature dependent, B = B( T). We investigate the mechanisms of the field stabilization in detail. The screening parameters for electric and magnetic fields—the Debye, m D ( B, T), and magnetic, m magn ( B, T), masses—are calculated. It is shown that, in the field presence, the former one is smaller than at zero field. The magnetic mass of the (chromo)magnetic fields is determined to be zero, as for usual U(1) magnetic field. We also show that the vacuum magnetization stops at temperatures below the electroweak phase transition temperature, T ? T ew , when a scalar condensate creates. These properties make reasonable a possibility that the intergalactic magnetic fields observed recently were spontaneously generated in the hot Universe at the reheating epoch due to vacuum polarization of non-Abelian gauge fields. We present a procedure for estimating the field strengths B( T) at different temperatures. In particular, the value of B( T ew ) ˜ 1014 G, at T ew is estimated with taking into consideration the observed intergalactic magnetic field B 0 ˜ 10-15 G. The magnetic field scale is also estimated. Some model dependent peculiarities of the phenomena studied are briefly discussed.

Demchik, V.; Skalozub, V.

2015-01-01

96

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

97

Evolution of Structure in the Intergalactic Medium and the Nature of the LY-Alpha Forest  

NASA Technical Reports Server (NTRS)

We have performed a detailed statistical study of the evolution of structure in a photoionized intergalactic medium (IGM) using analytical simulations to extend the calculation into the mildly nonlinear density regime found to prevail at z = 3. Our work is based on a simple fundamental conjecture: that the probability distribution function of the density of baryonic diffuse matter in the universe is described by a lognormal (LN) random field. The LN distribution has several attractive features and follows plausibly from the assumption of initial linear Gaussian density and velocity fluctuations at arbitrarily early times. Starting with a suitably normalized power spectrum of primordial fluctuations in a universe dominated by cold dark matter (CDM), we compute the behavior of the baryonic matter, which moves slowly toward minima in the dark matter potential on scales larger than the Jeans length. We have computed two models that succeed in matching observations. One is a nonstandard CDM model with OMEGA = 1, h = 0.5, and GAMMA = 0.3, and the other is a low-density flat model with a cosmological constant (LCDM), with OMEGA = 0.4, OMEGA(sub LAMBDA) = 0.6, and h = 0.65. In both models, the variance of the density distribution function grows with time, reaching unity at about z = 4, where the simulation yields spectra that closely resemble the Ly-alpha forest absorption seen in the spectra of high-z quasars. The calculations also successfully predict the observed properties of the Ly-alpha forest clouds and their evolution from z = 4 down to at least z = 2, assuming a constant intensity for the metagalactic UV background over this redshift range. However, in our model the forest is not due to discrete clouds, but rather to fluctuations in a continuous intergalactic medium. At z = 3; typical clouds with measured neutral hydrogen column densities N(sub H I) = 10(exp 13.3), 10(exp 13.5), and 10(exp 11.5) /sq cm correspond to fluctuations with mean total densities approximately 10, 1, and 0.1 times the universal mean baryon density. Perhaps surprisingly, fluctuations whose amplitudes are less than or equal to the mean density still appear as "clouds" because in our model more than 70% of the volume of the IGM at z = 3 is filled with gas at densities below the mean value.

Bi, Hongguang; Davidsen, Arthur F.

1997-01-01

98

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

99

Observations of the Intergalactic Medium and the Cosmic Web in the SKA era  

E-print Network

The interaction of galaxies with their environment, the Intergalactic Medium (IGM), is an important aspect of galaxy formation. One of the most fundamental, but unanswered questions in the evolution of galaxies is how gas circulates in and around galaxies and how it enters the galaxies to support star formation. We have several lines of evidence that the observed evolution of star formation requires gas accretion from the IGM at all times and on all cosmic scales. This gas remains largely unaccounted for and the outstanding questions are where this gas resides and what the physical mechanisms of accretion are. The gas is expected to be embedded in an extended cosmic web made of sheets and filaments. Such large-scale filaments of gas are expected by cosmological numerical simulations, which have made significant progress in recent years. Such simulations do not only model the large scale structure of the cosmic web, but also investigate the neutral gas component. To truly make significant progress in understan...

Popping, A; Staveley-Smith, L; Obreschkow, D; Jozsa, G I; Pisano, D J

2015-01-01

100

Faraday Rotation Measure due to the Intergalactic Magnetic Field II: the Cosmological Contribution  

E-print Network

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 root-mean-square (rms) value increases with redshift and saturates for $z \\ga 1$. The saturated value is RM$_{\\rm rms} \\approx$ several ${\\rm rad m^{-2}}$. The probability distribution function of $|{\\rm RM}|$ follows the lognormal distribution. The power spectrum has a broad plateau over the angular scale of $\\sim 1...

Akahori, Takuya

2011-01-01

101

Intergalactic Magnetic Field and Arrival Direction of Ultra-High-Energy Protons  

E-print Network

We studied how the intergalactic magnetic field (IGMF) affects the propagation of super-GZK protons that originate from extragalactic sources within the local GZK sphere. Toward this end, we set up hypothetical sources of ultra-high-energy cosmic-rays (UHECRs), virtual observers, and the magnetized cosmic web in a model universe constructed from cosmological structure formation simulations. We then arranged a set of reference objects mimicking active galactic nuclei (AGNs) in the local universe, with which correlations of simulated UHECR events are analyzed. With our model IGMF, the deflection angle between the arrival direction of super-GZK protons and the sky position of their actual sources is quite large with the mean value of $ \\sim 15^{\\circ}$ and the median value of $\\tilde \\theta \\sim 7 - 10^{\\circ}$. On the other hand, the separation angle between the arrival direction and the sky position of nearest reference objects is substantially smaller with $ \\sim 3.5 - 4^{\\circ}$, which is similar to the mean...

Ryu, Dongsu; Kang, Hyesung

2009-01-01

102

Constraining the baryon fraction in the Warm Hot Intergalactic Medium at low redshifts with PLANCK data  

E-print Network

We cross-correlate a template of the matter density field tracing the large-scale filamentary distribution of the Warm-Hot Intergalactic Medium out to ~90 Mpc/h with foreground cleaned Planck Nominal Cosmic Microwave Background (CMB) maps. The template traces the projected matter density reconstructed from the Two-Micron All-Sky Redshift Survey of galaxies and models the spatial distribution of filaments. After applying a filtering technique in order to reduce the unwanted 1/f noise in the CMB data and potential large-scale foreground residuals, we find a marginal signal with a signal-to-noise from 0.84 to 1.39 at the different Planck frequencies, and with a frequency dependence compatible with the thermal Sunyaev-Zel'dovich (tSZ) effect. At the 95% confidence level we set an upper limit to the cross-correlation at zero lag of < 0.17 muK. These results were obtained in a region covering 60% of the full sky, which is left after masking out the Galaxy, point sources and galaxy clusters. The significance of t...

Genova-Santos, Ricardo; Kitaura, Francisco-Shu; Muecket, Jan P

2015-01-01

103

The Volume Fraction of Ionized Intergalactic Gas at Redshift z=6.5  

E-print Network

The observed number density of Lyman-alpha sources implies a minimum volume of the inter-galactic medium that must be ionized, in order to allow the Lyman-alpha photons to escape attenuation. We estimate this volume by assigning to each Lyman-alpha emitter the minimum Stromgren sphere that would allow half its Lyman-alpha photons to escape. This implies a lower limit to ionized gas volume fraction of 20-50% at redshift z=6.5. This is a lower limit in two ways: First, we conservatively assume that the Lyman-alpha sources seen (at a relatively bright flux limit) are the only ones present; and second, we assume the smallest Stromgren sphere volume that will allow the photons to escape. This limit is completely independent of what ionizing photon sources produced the bubbles. Deeper Lyman-alpha surveys are possible with present technology, and can strengthen these limits by detecting a higher density of Lyman-alpha galaxies.

Sangeeta Malhotra; James Rhoads

2005-11-07

104

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

105

Heating and ionization of the primordial intergalactic medium by high-mass X-ray binaries  

NASA Astrophysics Data System (ADS)

We investigate the influence of high-mass X-ray binaries (HMXBs) on their high-redshift environments. Using a one-dimensional radiative transfer code, we predict the ionization and temperature profiles surrounding a coeval stellar population, composed of main-sequence stars and HMXBs, at various times after its formation. We consider both uniform density surroundings, and a cluster embedded in a 108 M? Navarro-Frenk-White (NFW) halo. HMXBs in a constant density environment produce negligible enhanced ionization because of their high-energy spectral energy distributions and short lifetimes. In this case, HMXBs only marginally contribute to the local heating rate. For NFW profiles, radiation from main-sequence stars cannot prevent the initially ionized volume from recombining since it is unable to penetrate the high-density galactic core. However, HMXB photons stall recombinations behind the front, keeping it partially ionized for longer. The increased electron density in these partially ionized regions promotes further cooling, resulting in lower intergalactic medium (IGM) temperatures. In the context of this starburst model, we have shown that HMXBs do not make a major contribution to reionization or IGM heating. However, X-ray escape fractions are high in both density profile cases. Continuous star formation may result in the build up of X-rays over time, reducing the ionization time-scale and potentially leading to low level ionization of the distant IGM.

Knevitt, G.; Wynn, G. A.; Power, C.; Bolton, J. S.

2014-12-01

106

Strength of the Spontaneously Emitted Collective Aperiodic Magnetic Field Fluctuations in the Reionized Early Intergalactic Medium  

NASA Astrophysics Data System (ADS)

Nonmagnetized, fully ionized plasmas spontaneously emit aperiodic turbulent magnetic field fluctuations. Its fluctuation intensities are dominated by the contribution from a recently discovered collective, damped mode, which modifies the earlier estimate of the total magnetic field strength in a thermal nonrelativistic electron-proton plasma to |\\delta B|=24\\beta _e^{1/4}(gn_em_ec^2)^{1/2} G, where g denotes the plasma parameter and ? e the thermal electron velocity in units of the speed of light, in the case of no collisional damping. Accounting for simultaneous viscous damping reduces the estimate to |?B|eq = 2305g(nemec 2)1/2 G, depending only on the plasma parameter g and the electron density ne . For the unmagnetized intergalactic medium, immediately after the reionization onset the field strengths from this mechanism are about 6.8 × 10-13 G for no collisional damping and 1.5 × 10-16 G for viscous damping. Maximum spatial scales of 1015 cm of the emitted aperiodic fluctuations in cosmic voids are possible.

Schlickeiser, R.; Felten, T.

2013-11-01

107

ANISOTROPIC ACTIVE GALACTIC NUCLEUS OUTFLOWS AND ENRICHMENT OF THE INTERGALACTIC MEDIUM. I. METAL DISTRIBUTION  

SciTech Connect

We investigate the cosmological-scale influence of outflows driven by active galactic nuclei (AGNs) on metal enrichment of the intergalactic medium (IGM). AGNs are located in dense cosmological structures which tend to be anisotropic. We designed a semianalytical model for anisotropic AGN outflows which expand away along the direction of least resistance. This model was implemented into a cosmological numerical simulation algorithm for simulating the growth of large-scale structure in the universe. Using this modified algorithm, we perform a series of nine simulations inside cosmological volumes of size (128 h {sup -1} Mpc){sup 3}, in a concordance LAMBDACDM universe, varying the opening angle of the outflows, the lifetimes of the AGNs, their kinetic fractions, and their level of clustering. For each simulation, we compute the volume fraction of the IGM enriched in metals by the outflows. The resulting enriched volume fractions are relatively small at z approx> 2.5, and then grow rapidly afterward up to z = 0. We find that AGN outflows enrich from 65% to 100% of the entire universe at the present epoch, for different values of the model parameters. The enriched volume fraction depends weakly on the opening angle of the outflows. However, increasingly anisotropic outflows preferentially enrich underdense regions, a trend found more prominent at higher redshifts and decreasing at lower redshifts. The enriched volume fraction increases with increasing kinetic fraction and decreasing AGN lifetime, and level of clustering.

Germain, Joel; Barai, Paramita; Martel, Hugo [Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, QC (Canada)

2009-10-20

108

The Hot Inter-Galactic Medium and the Cosmic Microwave Background  

E-print Network

The physical characteristics of the Lyman-alpha forest cloud systems are combined with observations on the baryonic mass density of the Universe and constraints from primordial nucleosynthesis to set boundary conditions on the Intergalactic Medium (IGM) at the epoch of z=2.5. The Universe is considered a closed system and allowed to expand adiabatically from the epoch when QSOs first ionized the IGM (5 <= z_on <= 20). The average kinetic energy of a gas is calculated in the region where the gas transitions from relativistic to non-relativistic behavior. All of the above measurements are then used to determine the thermal history of the IGM in the redshift range 2.5 <= z <= z_on. The hot IGM is assumed to inverse Compton scatter photons from the Cosmic Microwave Background (CMBR) and consequently distort the CMBR as seen at the present epoch. The temperature of the IGM at z=2.5 and the epoch z_on are adjusted, within the constraints defined above, to give the best overall agreement with published data on the temperature of the IGM. We find that the model of the IGM proposed here does not grossly distort the CMBR, and in fact agrees quite closely with the preliminary results from the Cosmic Background Explorer (COBE) satellite. However, our model of the IGM cannot explain the observed cosmic x ray background. This paper was originally written in 1990. It was never submitted for publication.

Michael Fisher

2007-05-01

109

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

110

The Intergalactic and Circumgalactic Medium surrounding Star-Forming Galaxies at Redshifts 2 < z < 3  

NASA Astrophysics Data System (ADS)

We present measurements of the spatial distribution, kinematics, and physical properties of gas in the circumgalactic medium (CGM) of 2.0 < z < 2.8 UV color-selected galaxies as well as within the 2 < z < 3 intergalactic medium (IGM). These measurements are derived from Voigt profile decomposition of the full Lyalpha and Lybeta forest in 15 high-resolution, high signal-to-noise ratio QSO spectra resulting in a catalog of ˜ 6000 H I absorbers. Chapter 2 of this thesis focuses on H I surrounding high-z star-forming galaxies drawn from the Keck Baryonic Structure Survey (KBSS). The KBSS is a unique spectroscopic survey of the distant universe designed to explore the details of the connection between galaxies and intergalactic baryons within the same survey volumes. The KBSS combines high-quality background QSO spectroscopy with large densely-sampled galaxy redshift surveys to probe the CGM at scales of ˜ 50 kpc to a few Mpc. Based on these data, Chapter 2 presents the first quantitative measurements of the distribution, column density, kinematics, and absorber line widths of neutral hydrogen surrounding high-z star-forming galaxies. Chapter 3 focuses on the thermal properties of the diffuse IGM. This analysis relies on measurements of the ˜ 6000 absorber line widths to constrain the thermal and turbulent velocities of absorbing "clouds." A positive correlation between the column density of H I and the minimum line width is recovered and implies a temperature-density relation within the low-density IGM for which higher-density regions are hotter, as is predicted by simple theoretical arguments. Chapter 4 presents new measurements of the opacity of the IGM and CGM to hydrogen-ionizing photons. The chapter begins with a revised measurement of the H I column density distribution based on this new absorption line catalog that, due to the inclusion of high-order Lyman lines, provides the first statistically robust measurement of the frequency of absorbers with H I column densities 14 ? log(NHI/cm--2) ? 17.2. Also presented are the first measurements of the column density distribution of H I within the CGM (50 < d < 300 pkpc) of high-z galaxies. These distributions are used to calculate the total opacity of the IGM and IGM+CGM and to revise previous measurements of the mean free path of hydrogen-ionizing photons within the IGM. This chapter also considers the effect of the surrounding CGM on the transmission of ionizing photons out of the sites of active star-formation and into the IGM. This thesis concludes with a brief discussion of work in progress focused on understanding the distribution of metals within the CGM of KBSS galaxies. Appendix B discusses my contributions to the MOSFIRE instrumentation project.

Rudie, Gwen C.

111

Far Ultraviolet Spectroscopy of the Intergalactic and Interstellar Absorption Toward 3C 273  

NASA Technical Reports Server (NTRS)

We present Far Ultraviolet Spectroscopic Explorer observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C273. We identify Ly-beta absorption in eight of the known intergalactic Ly-alpha absorbers along the sight line with the rest-frame equivalent widths W(sub r)(Ly-alpha) > 50 micro-angstroms. Refined estimates of the H(I) column densities and Doppler parameters (b) of the clouds are presented. We find a range of b = 16-46 km/s. We detect multiple H(I) lines (Ly-beta - Ly-theta) in the 1590 km/s Virgo absorber and estimate logN(H(I)) = 15.85 +/- 0.10, ten times more H(I) than all of the other absorbers along the sight line combined. The Doppler width of this absorber, b = 16 km/s, implies T < 15,000 K. We detect O(VI) absorption at 1015 km/s at the 2-3(sigma) level that may be associated with hot, X-ray emitting gas in the Virgo Cluster. We detect weak C(III) and O(VI) absorption in the IGM at z=0.12007; this absorber is predominantly ionized and has N(H+)/N(H(I)) > 4000/Z, where Z is the metallicity. Strong Galactic interstellar O(VI) is present between -100 and +100 km/s with an additional high-velocity wing containing about 13% of the total O(VI) between +100 and +240 km/s. The Galactic O(VI), N(V), and C(IV) lines have similar shapes, with roughly constant ratios across the -100 to +100 km/s velocity range. The high velocity O(VI) wing is not detected in other species. Much of the interstellar high ion absorption probably occurs within a highly fragmented medium within the Loop IV remnant or in the outer cavity walls of the remnant. Multiple hot gas production mechanisms are required. The broad O(VI) absorption wing likely traces the expulsion of hot gas out of the Galactic disk into the halo. A flux limit of 5.4 x 10(epx -16) erg/sq cm/s on the amount of diffuse O(VI) emission present = 3.5' off the 3C273 sight line combined with the observed O(VI) column density toward 3C273, logN O(VI) = 14.73 +/- 0.04, implies n(sub e) < 0.02/cubic cm and P/k < 11,500/cubic cm for an assumed temperature of 3 x 10(exp 5) K. The elemental abundances in the neutral and weakly-ionized interstellar clouds are similar to those found for other halo clouds. The warm neutral and warm ionized clouds along the sight line have similar dust-phase abundances, implying that the properties of the dust grains in the two types of clouds are similar. Interstellar H2 absorption is present at positive velocities at a level of logN(H2) = 15.71, but is very weak at the velocities of the main column density concentration along the sight line observed in H(I) 21 cm emission.

Sembach, Kenneth R.; Howk, J. Christopher; Savage, Blair D.; Shull, J. Michael; Oegerle, William R.; Fisher, Richard R. (Technical Monitor)

2001-01-01

112

STAR FORMATION FEEDBACK AND METAL-ENRICHMENT HISTORY OF THE INTERGALACTIC MEDIUM  

SciTech Connect

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 {delta} {>=} 10. Most C IV and O VI absorbers are located within shocked regions of elevated temperature (T {>=} 2 x 10{sup 4} K), overdensity ({delta} {>=} 10), and metallicity ([Z/Z{sub 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 {approx} 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 cm{sup 2}=12-15 are reasonably reproduced by the simulations. The evolution of mass densities contained in C IV and O VI lines, {Omega}{sub CIV} and {Omega}{sub OVI}, 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 cm{sup 2}=12-15 is only {approx}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 = 10{sup 4.5}-10{sup 7} K) gaseous phase, heated up by GSW feedback shocks. Their mass distribution is broadly peaked at {delta}=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, E-mail: cen@astro.princeton.edu, E-mail: nchisari@astro.princeton.edu [Princeton University Observatory, Princeton, NJ 08544 (United States)

2011-04-10

113

INTERGALACTIC MAGNETIC FIELD AND ARRIVAL DIRECTION OF ULTRA-HIGH-ENERGY PROTONS  

SciTech Connect

We studied how the intergalactic magnetic field (IGMF) affects the propagation of super-Greisen-Zatsepin-Kuz'min (GZK) protons that originate from extragalactic sources within the local GZK sphere. To this end, we set up hypothetical sources of ultra-high-energy cosmic rays (UHECRs), virtual observers, and the magnetized cosmic web in a model universe constructed from cosmological structure formation simulations. We then arranged a set of reference objects mimicking active galactic nuclei (AGNs) in the local universe, with which correlations of simulated UHECR events are analyzed. With our model IGMF, the deflection angle between the arrival direction of super-GZK protons and the sky position of their actual sources is quite large with a mean value of (theta) {approx} 15 deg. and a median value of THETA-tilde{approx}7 deg. - 10 deg. On the other hand, the separation angle between the arrival direction and the sky position of nearest reference objects is substantially smaller with (S) {approx} 3.{sup 0}5-4{sup 0}, which is similar to the mean angular distance in the sky to nearest neighbors among the reference objects. This is a direct consequence of our model that the sources, observers, reference objects, and the IGMF all trace the matter distribution of the universe. The result implies that extragalactic objects lying closest to the arrival direction of UHECRs are not necessarily their actual sources. With our model for the distribution of reference objects, the fraction of super-GZK proton events, whose closest AGNs are true sources, is less than 1/3. We discussed implications of our findings for correlation studies of real UHECR events.

Ryu, Dongsu [Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Das, Santabrata [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Kang, Hyesung, E-mail: ryu@canopus.cnu.ac.k, E-mail: sbdas@iitg.ernet.i, E-mail: kang@uju.es.pusan.ac.k [Department of Earth Sciences, Pusan National University, Pusan 609-735 (Korea, Republic of)

2010-02-20

114

Confirming the Detection of an Intergalactic X-ray Absorber Toward PKS 2155-304  

E-print Network

We present new observations on PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer (LETG), using the Advanced CCD Imaging Spectrometer (ACIS). We confirm the detection of an absorption line plausibly identified as OVIII Ly-alpha from the warm-hot intergalactic medium associated with a small group of galaxies along the line of sight, as originally reported by Fang et al. 2002 (here after FANG02). Combining the previous observations in FANG02 and five new, long observations on the same target, we increase the total exposure time by a factor of three, and the total counts per resolution element by a factor of five. The measured line equivalent width is smaller than that observed in FANG02, but still consistent at 90% confidence. We also analyze the XMM-Newton observations on the same target, as well as observations using the Chandra LETG and the High Resolution Camera (HRC) combination. These observations have been used to challenge our reported detection. While no line is seen in either the XMM-Newton and the Chandra LETG+HRC data, we find that our result is consistent with the upper limits from both data sets. We attribute the non-detection to (1) higher quality of the Chandra LETG+ACIS spectrum, and (2) the rather extended wings of the line spread functions of both the XMM RGS and the Chandra LETG+HRC. We discuss the implication of our observation on the temperature and density of the absorber. We also confirm the detection of z ~ 0 OVII absorption and, comparing with previous Chandra analysis, we obtain much tighter constraints on the line properties.

Taotao Fang; Claude R. Canizares; Yangsen Yao

2007-08-14

115

COSMOLOGICAL SIMULATIONS OF INTERGALACTIC MEDIUM EVOLUTION. I. TEST OF THE SUBGRID CHEMICAL ENRICHMENT MODEL  

SciTech Connect

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 [Département de physique, de Génie Physique et d'Optique, Université Laval, Québec, QC G1V 0A6 (Canada)

2013-11-10

116

Characterizing the cool and warm-hot intergalactic medium in clusters at z < 0.4  

NASA Astrophysics Data System (ADS)

Dedicated surveys with HST/COS and previous UV spectrometers have revealed that present-day galaxies of essentially all mass and spectral-type harbor a substantial reservoir of cool (T~10^4K) and warm (T~10^5-10^6 K) gas in their halos, defining a circumgalactic medium (CGM) around galaxies. At much higher halo mass scales, groups and clusters exhibit a hot (T~10^6-10^7K) tenuous plasma designated the intragroup or intracluster medium (IGrM, ICM). Although these massive structures hosts up to hundreds of individual galaxies, it is unknown whether the IGrM/ICM also contains cool or warm phases. Numerical simulations offer some guidance, predicting that the outer environment is warm (T<10^6K) and recent work on Virgo reveals a cool phase close to its virial radius. Here we venture into this unexplored territory, and propose to use HST/COS spectroscopy of 6 background QSOs to search for the cool (narrow HI Lya) and the warm/highly-ionized gas (broad HI Lya and OVI) at impact parameters of ~0.2 - 3 R_200 from 11 clusters lying in the foreground. We will use both G130M and G160M gratings to cover the full FUV spectral range to simultaneosly survey HI Lya and OVI at the redshifts of the intervening structures. This first systematic study of cool and warm gas in massive, low-z halos will enable us to: (1) quantify the contribution of the warm-hot intergalactic medium (WHIM) within or near massive groups and clusters; (2) explore the signatures of tidal and ram-pressure stripping of group/cluster members; (3) search for evidence of expulsion of baryons via feedback processes; and (4) search for evidence of cold/hot accretion modes in these massive halos.

Tejos, Nicolas

2014-10-01

117

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

118

Simulations of thermally broadened H I Ly ? absorption arising in the warm-hot intergalactic medium  

NASA Astrophysics Data System (ADS)

Recent far-ultraviolet (FUV) absorption line measurements of low-redshift quasars have unveiled a population of intervening broad H i Ly ? absorbers (BLAs) with large Doppler parameters (b? 40 km s-1). If the large width of these lines is dominated by thermal line broadening, the BLAs may trace highly-ionized gas in the warm-hot intergalactic medium (WHIM) in the temperature range T? 10^5{-}106 K, a gas phase that is expected to contain a large fraction of the baryons at low redshift. In this paper we use a hydrodynamical simulation to study frequency, distribution, physical conditions, and baryon content of the BLAs at z? 0. From our simulated spectra we derive a number of BLAs per unit redshift of (dN/dz)_BLA? 38 for H i absorbers with log (N(cm-2)/b(km s-1))? 10.7, b?40 km s-1, and total hydrogen column densities N(H ii)? 1020.5 cm-2. The baryon content of these systems is ?_b(BLA)=0.0121 h65 -1, which represents ˜ 25 percent of the total baryon budget in our simulation. Our results thus support the idea that BLAs represent a significant baryon reservoir at low redshift. BLAs predominantly trace shock-heated collisionally ionized WHIM gas at temperatures log T? 4.4{-}6.2. About 27 percent of the BLAs in our simulation originate in the photoionized Ly ? forest (log T<4.3) and their large line widths are determined by non-thermal broadening effects such as unresolved velocity structure and macroscopic turbulence. Our simulation implies that for a large-enough sample of BLAs in FUV spectra it is possible to obtain a reasonable approximation of the baryon content of these systems solely from the measured H i column densities and b values.

Richter, P.; Fang, T.; Bryan, G. L.

2006-06-01

119

TURBULENCE IN THE INTERGALACTIC MEDIUM: SOLENOIDAL AND DILATATIONAL MOTIONS AND THE IMPACT OF NUMERICAL VISCOSITY  

SciTech Connect

We use a suite of cosmological hydrodynamical simulations, run by two fixed grid codes, to investigate the properties of solenoidal and dilatational motions of the intergalactic medium (IGM) and the impact of numerical viscosity on turbulence in an ?CDM universe. The codes differ only in the spatial difference discretization. We find that (1) The vortical motion grows rapidly since z = 2 and reaches ?10 km s{sup –1}-90 km s{sup –1} at z = 0. Meanwhile, the small-scale compressive ratio r{sub CS} drops from 0.84 to 0.47, indicating comparable vortical and compressive motions at z = 0. (2) Power spectra of the solenoidal velocity possess two regimes, ?k {sup –0.89} and ?k {sup –2.02}, while the total and dilatational velocity follow the scaling k {sup –1.88} and k {sup –2.20}, respectively, in the turbulent range. The IGM turbulence may contain two distinct phases, the supersonic and post-supersonic phases. (3) The non-thermal pressure support, measured by the vortical kinetic energy, is comparable with the thermal pressure for ?{sub b} ? 10-100, or T < 10{sup 5.5} K at z = 0.0. The deviation of the baryon fraction from the cosmic mean shows a preliminary positive correlation with the turbulence pressure support. (4) A relatively higher numerical viscosity would dissipate both the compressive and vortical motions of the IGM into thermal energy more effectively, resulting in less developed vorticity, remarkably shortened inertial range, and leading to a non-negligible uncertainty in the thermal history of gas accretion. Shocks in regions outside of clusters are significantly suppressed by numerical viscosity since z = 2, which may directly cause the different levels of turbulence between the two codes.

Zhu, Weishan; Gu, Qiusheng [School of Astronomy and Space Science, Nanjing University, Nanjing, 210092 (China); Feng, Long-long [Purple Mountain Observatory, Nanjing, 210008 (China); Xia, Yinhua [School of Mathematical Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shu, Chi-Wang [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States); Fang, Li-Zhi [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States)

2013-11-01

120

THE TEMPERATURE-DENSITY RELATION IN THE INTERGALACTIC MEDIUM AT REDSHIFT (z) = 2.4  

SciTech Connect

We present new measurements of the temperature-density (T-{rho}) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of {approx}6000 individual H I absorbers fitted with Voigt profiles constrained in all cases by multiple Lyman series transitions. We find model-independent evidence for a positive correlation between the column density of H I (N{sub HI}) and the minimum observed velocity width of absorbers (b{sub min}). With minimal interpretation, this implies that the T-{rho} relation in the IGM is not 'inverted', contrary to many recent studies. Fitting b{sub min} as a function of N{sub HI} results in line-width-column-density dependence of the form b{sub min} = b{sub 0}(N{sub HI}/N{sub HI,0}){sup {Gamma}-1} with a minimum line width at mean density ({rho}/{rho}-bar = 1, N{sub HI,0} = 10{sup 13.6} cm{sup -2}) of b{sub 0} = 17.9 {+-} 0.2 km s{sup -1} and a power-law index of ({Gamma} - 1) = 0.15 {+-} 0.02. Using analytic arguments, these measurements imply an 'equation of state' for the IGM at (z) = 2.4 of the form T=T{sub 0} ({rho}/{rho}-bar){sup {gamma}-1} with a temperature at mean density of T{sub 0} = [1.94 {+-} 0.05] Multiplication-Sign 10{sup 4} K and a power-law index ({gamma} - 1) = 0.46 {+-} 0.05.

Rudie, Gwen C.; Steidel, Charles C. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Pettini, Max, E-mail: gwen@astro.caltech.edu [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

2012-10-01

121

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

122

ANISOTROPIC ACTIVE GALACTIC NUCLEUS OUTFLOWS AND ENRICHMENT OF THE INTERGALACTIC MEDIUM. II. METALLICITY  

SciTech Connect

We investigate the large-scale influence of outflows from active galactic nuclei (AGNs) in enriching the intergalactic medium (IGM) with metals in a cosmological context. We combine cosmological simulations of large-scale structure formation with a detailed model of metal enrichment, in which outflows expand anisotropically along the direction of least resistance, distributing metals into the IGM. The metals carried by the outflows are generated by two separate stellar populations: stars located near the central AGN, and stars located in the greater galaxy. Using this algorithm, we performed a series of five simulations of the propagation of AGN-driven outflows in a cosmological volume of size (128 h{sup -1} Mpc){sup 3} in a {Lambda}CDM universe, and analyze the resulting metal enrichment of the IGM. We found that the metallicity induced in the IGM is greatly dominated by AGNs having bolometric luminosity L>10{sup 9} L{sub sun}, sources with 10{sup 8} < L/L{sub sun} < 10{sup 9} having a negligible contribution. Our simulations produced an average IGM metallicity of [O/H] = -5 at z = 5.5, which then rises gradually, and remains relatively flat at a value [O/H] = -2.8 between z = 2 and z = 0. The ejection of metals from AGN host galaxies by AGN-driven outflows is found to enrich the IGM to >10%-20% of the observed values, the number dependent on redshift. The enriched IGM volume fractions are small at z>3, then rise rapidly to the following values at z = 0: 6%-10% of the volume enriched to [O/H]> - 2.5, 14%-24% volume to [O/H]> - 3, and 34%-45% volume to [O/H]> - 4. At z {>=} 2, there is a gradient of the induced enrichment, the metallicity decreasing with increasing IGM density, enriching the underdense IGM to higher metallicities, a trend more prominent with increasing anisotropy of the outflows. This can explain observations of the metal-enriched low-density IGM at z {approx} 3-4.

Barai, Paramita [Department of Physics and Astronomy, University of Nevada at Las Vegas, Las Vegas, NV (United States); Martel, Hugo; Germain, Joel [Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, QC (Canada)

2011-01-20

123

ANISOTROPIC GALACTIC OUTFLOWS AND ENRICHMENT OF THE INTERGALACTIC MEDIUM. II. NUMERICAL SIMULATIONS  

SciTech Connect

We combine an analytic model for anisotropic outflows and galaxy formation with numerical simulations of large-scale structure and halo formation to study the impact of galactic outflows on the evolution of the intergalactic medium (IGM). Using this algorithm, we have simulated the evolution of a comoving volume of size (15 Mpc){sup 3} in the {Lambda}CDM universe. Using an N-body simulation starting at redshift z = 24, we follow the formation of galaxies and simulate the galactic outflows produced by these galaxies. Outflows are modeled as bipolar cones with opening angle {alpha}, which expand along the direction of least resistance. We consider five opening angles: {alpha} = 60{sup 0}, 90{sup 0}, 120{sup 0}, 150{sup 0}, and 180{sup 0} (isotropic outflows). We also consider the effect of photoionization suppression of galaxy formation by reionization at redshift z = 6. Anisotropic outflows travel preferentially into low-density regions, away from cosmological structures (filaments and pancakes) where galaxies form. These anisotropic outflows are less likely to overlap with one another than isotropic ones. They are also less likely to hit pre-galactic collapsing halos and strip them of their gas, preventing a galaxy from forming. Going from 180{sup 0} to 60{sup 0}, the number of galaxies that actually form doubles, producing twice as many outflows, and these outflows overlap to a lesser extent. As a result, the metal volume filling factor of the IGM goes from 8% for isotropic outflows up to 28% for anisotropic ones. High-density regions are more efficiently enriched than low-density ones ({approx}80% compared to {approx}20% by volume), even though most enriched regions are low densities. Increasing the anisotropy of outflows increases the extent of enrichment at all densities, low and high. This is in part because anisotropic outflows are more numerous. When this effect is factored out, we find that the probability a galaxy will enrich systems at densities up to 10 {rho}-bar is higher for increasingly anisotropic outflows. This is interpreted as an effect of the dynamical evolution of the IGM. Anisotropic outflows expand preferentially into underdense gas, but that gas can later accrete onto overdense structures. The inclusion of photoionization greatly reduces the formation of low-mass galaxies at redshifts z < 3. The result is a decline in the physical extent of galactic outflows after z = 3 as accretion overwhelms the expansion of new outflows and reduces feedback in underdense regions.

Pinsonneault, Steeve; Martel, Hugo [Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, QC G1K 7P4 (Canada); Pieri, Matthew M. [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States)

2010-12-20

124

Tracing baryons in the warm-hot intergalactic medium with broad Ly ? absorption  

NASA Astrophysics Data System (ADS)

We discuss physical properties and baryonic content of broad Ly ? absorbers (BLAs) at low redshift. These absorption systems, recently discovered in high-resolution, high-signal to noise quasar absorption line spectra, possibly trace the warm-hot intergalactic medium (WHIM) in the temperature range between 105 and 106 K. The central idea is that in ionization equilibrium WHIM filaments should contain a very small fraction of neutral gas (fH I˜ 10-5{-}10-6, typically), giving rise to weak intervening H i Ly ? absorption. Due to the high temperature of the WHIM, these Ly ? absorbers must be thermally broadened to Doppler parameters (b values) ? 40 km s-1. It is expected, however, that also non-thermal line broadening processes, line blends, and noise features can mimic broad spectral features, complicating the quantitative estimate of the baryon content of the BLAs. To extend previous BLA measurements we have reanalyzed archival STIS data of the two quasars H 1821+643 and PG 0953+415 and have identified 13 BLA candidates along a total (unblocked) redshift path of ? z=0.440. Combining our measurements with previous results for the lines of sight toward PG 1259+593 and PG 1116+215, the resulting new BLA sample consists of 20 reliably detected systems as well as 29 additional tentative cases, implying a BLA number density of dN_BLA/dz=22{-}53. Eight BLAs show associated absorption from H i Ly ? and/or O vi. The comparison between Ly ?, Ly ?, and O vi line widths suggests that non-thermal broadening and noise features substantially affect the observed BLA b value distribution. However, it remains unclear whether BLAs and O vi absorbers trace the same gas phase in the WHIM filaments. We estimate that the contribution of BLAs to the baryon density at z=0 is ?_b(BLA)? 0.0027 h70 -1 for absorbers with log [N(cm-2)/b(km s-1)] ? 11.3. This number indicates that WHIM broad Ly ? absorbers contain a substantial fraction of the baryons in the local Universe.

Richter, P.; Savage, B. D.; Sembach, K. R.; Tripp, T. M.

2006-01-01

125

The baryon density at z = 0.9-1.9. Tracing the warm-hot intergalactic medium with broad Lyman ? absorption  

NASA Astrophysics Data System (ADS)

Aims:We present an analysis of the Lyman ? forests of five quasar spectra in the near UV. Properties of the intergalactic medium (IGM) at an intermediate redshift interval (0.9? z?1.9) are studied. The amount of baryons in the diffuse photoionised IGM and the warm-hot intergalactic medium (WHIM) are traced to get constraints on the redshift evolution of the different phases of the intergalactic gas. Methods: The baryon density of the diffuse IGM is determined with photoionisation calculations under the assumption of local hydrostatic equilibrium. We assume that the gas is ionised by a metagalactic background radiation with a Haardt & Madau (2001, Clusters of Galaxies and the High Redshift Universe Observed in X-rays) spectrum. The WHIM is traced with broad Lyman ? (BLA) absorption. The properties of a number of BLA detections are studied. Under the assumption of collisional ionisation equilibrium a lower limit to the baryon density could be estimated. Results: It is found that the diffuse photoionised IGM contains at least ~25% of the total baryonic matter at redshifts 1? z?2. For the WHIM a lower limit of ~2.4% could be determined. Furthermore, the data indicates that the intergalactic gas is in a state of evolution at z˜1.5. We confirm that a considerable part of the WHIM is created between z=1 and z=2.

Prause, N.; Reimers, D.; Fechner, C.; Janknecht, E.

2007-07-01

126

High Resolution Spectroscopy of X-ray Quasars: Searching for the X-ray Absorption from the Warm-Hot Intergalactic Medium  

E-print Network

We present a survey of six low- to moderate-redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the warm-hot intergalactic ...

Fang, Taotao

127

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

128

The Fluctuating Intergalactic Radiation Field at Redshifts z = 2.3-2.9 from He II and H I Absorption toward HE 2347-4342  

NASA Astrophysics Data System (ADS)

We provide an in-depth analysis of the He II and H I absorption in the intergalactic medium (IGM) at redshifts z=2.3-2.9 toward HE 2347-4342, using spectra from the Far Ultraviolet Spectroscopic Explorer and the Ultraviolet-Visual Echelle Spectrograph on the Very Large Telescope. Following up on our earlier study, we focus here on two major topics: (1) small-scale variability (?z~10-3) in the ratio ?=N(HeII)/N(HI) and (2) an observed correlation of high-? absorbers (soft radiation fields) with voids in the (H I) Ly? distribution. These effects may reflect fluctuations in the ionizing sources on scales of 1 Mpc, together with radiative transfer through a filamentary IGM whose opacity variations control the penetration of 1-5 ryd radiation over 30-40 Mpc distances. Given the photon statistics and backgrounds, we can measure optical depths over the ranges 0.1200 may require additional contributions from starburst galaxies, heavily filtered quasar radiation, or density variations. Regions with ?<30 may indicate the presence of local hard sources. We find that ? is higher in ``void'' regions, where H I is weak or undetected and ~80% of the path length has ?>100. These voids may be ionized by local soft sources (dwarf starbursts) or by QSO radiation softened by escape from the active galactic nucleus cores or transfer through the ``cosmic web.'' The apparent differences in ionizing spectra may help to explain the 1.45 Gyr lag between the reionization epochs of H I (zHI~6.2+/-0.2) and He II (zHeII~2.8+/-0.2). This work is based on FUSE data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission, operated by the Johns Hopkins University under NASA contract NAS5-32985. Observations with the NASA/ESA Hubble Space Telescope were supported by the Space Telescope Science Institute, operated by AURA under NASA contract NAS5-26555. The VLT/UVES observations were obtained at the Paranal Observatory of the European Southern Observatory for program 166.A-0106(A).

Shull, J. Michael; Tumlinson, Jason; Giroux, Mark L.; Kriss, Gerard A.; Reimers, Dieter

2004-01-01

129

The spin temperature and 21cm brightness of the intergalactic medium in the pre-reionization era  

E-print Network

We use numerical hydrodynamical simulations of early structure formation in a LCDM universe to investigate the spin temperature and 21cm brightness of the diffuse intergalactic medium (IGM) prior to the epoch of cosmic reionization, at z<20. In the absence of any radiative heating, collisions between neutral hydrogen atoms can efficiently decouple the spin temperature from the CMB only in dense minihalos and filaments. Shock heated gas shines in emission, surrounded by cooler gas visible in absorption. In the case of a warm, mostly neutral IGM, produced here by X-ray emission from an early miniquasar, the 21cm signal is strongly enhanced. Even slightly overdense filaments now shine in emission against the CMB, possibly allowing future radio arrays to probe the distribution of neutral hydrogen before reionization.

Michael Kuhlen; Piero Madau; Ryan Montgomery

2005-12-21

130

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

131

THE LOW-REDSHIFT INTERGALACTIC MEDIUM AS SEEN IN ARCHIVAL LEGACY HST/STIS AND FUSE DATA  

SciTech Connect

We present a comprehensive catalog of ultraviolet (HST/STIS and FUSE) absorbers in the low-redshift intergalactic medium (IGM) at z < 0.4. The catalog draws from much of the extensive literature on IGM absorption and reconciles discrepancies among several previous catalogs through a critical evaluation of all reported absorption features in light of new HST/COS data. We report on 746 H I absorbers down to a rest-frame equivalent width of 12 mA over a maximum redshift path length {Delta}z = 5.38. We also confirm 111 O VI absorbers, 29 C IV absorbers, and numerous absorption lines due to other metal ions. We characterize the bivariate distribution of absorbers in redshift and column density as a power law, {partial_derivative}{sup 2}N/{partial_derivative}z{partial_derivative}N) {proportional_to} N{sup -{beta}}, where {beta} = 2.08 {+-} 0.12 for O VI and {beta} = 1.68 {+-} 0.03 for H I. Utilizing a more sophisticated accounting technique than past work, our catalog accounts for {approx}43% of the baryons: 24% {+-} 2% in the photoionized Ly{alpha} forest and 19% {+-} 2% in the warm-hot IGM as traced by O VI. We discuss the large systematic effects of various assumed metallicities and ionization states on these calculations, and we implement recent simulation results in our estimates.

Tilton, Evan M.; Danforth, Charles W.; Michael Shull, J. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Ross, Teresa L., E-mail: evan.tilton@colorado.edu, E-mail: charles.danforth@colorado.edu, E-mail: michael.shull@colorado.edu, E-mail: rosst@nmsu.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

2012-11-10

132

Polarization of absorption lines as a diagnostics of circumstellar, interstellar and intergalactic magnetic fields: Fine structure atoms  

E-print Network

The relative population of the fine structure sublevels of an atom's ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational consequences for the interstellar and intergalactic medium, this results in the polarization of the absorption lines. In the paper we consider the conditions necessary for this effect and provide calculations of polarization from a few astrophysically important atoms and ions with multiple upper and lower levels for an arbitrary orientation of magnetic fields to the a) source of optical pumping, b) direction of observation, c) absorbed source. We also consider an astrophysically important ``degenerate'' case when the source of optical pumping coincides with the source of the absorbed radiation. We present analytical expressions that relate the degree of linear polarization and the intensity of absorption to the 3D orientation of the magnetic field with respect to the pumping source, the source of the absorbed radiation, and the direction of observations. We discuss how all these parameters can be determined via simultaneous observations of several absorption lines and suggest graphical means that are helpful in practical data interpretation. We prove that studies of absorption line polarization provide a unique tool to study 3D magnetic field topology in various astrophysical conditions.

Huirong Yan; A. Lazarian

2006-11-09

133

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

134

THE 21 cm FOREST AS A PROBE OF THE REIONIZATION AND THE TEMPERATURE OF THE INTERGALACTIC MEDIUM  

SciTech Connect

Using high-redshift radio sources as background, the 21 cm forest observations probe the neutral hydrogen absorption signatures of early structures along the lines of sight. Directly sensitive to the spin temperature of the hydrogen atoms, it complements the 21 cm tomography observations, and provides information on the temperature as well as the ionization state of the intergalactic medium (IGM). We use a radiative transfer simulation to investigate the 21 cm forest signals during the epoch of reionization. We first confirmed that the optical depth and equivalent width (EW) are good representations of the ionization and thermal state of the IGM. The features selected by their relative optical depth are excellent tracers of ionization fields, and the features selected by their absolute optical depth are very sensitive to the IGM temperature, so the IGM temperature information could potentially be extracted from 21 cm forest observation, thus breaking a degeneracy in 21 cm tomographic observation. With the EW statistics, we predict some observational consequences for 21 cm forest. From the distributions of EWs and the number evolution of absorbers and leakers with different EWs, we see clearly the cosmological evolution of ionization state of the IGM. The number density of potentially observable features decreases rapidly with increasing gas temperature. The sensitivity of the proposed EW statistic to the IGM temperature makes it a unique and potentially powerful probe of reionization. Missing small-scale structures, such as small filaments and minihalos that are unresolved in our current simulation, and lack of an accurate calculation of the IGM temperature, however, likely have rendered the presented signals quantitatively inaccurate. Finally, we discuss the requirements of the background radio sources for such observations, and find that signals with equivalent widths larger than 1 kHz are hopeful to be detected.

Xu Yidong; Fan Zuhui [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Chen Xuelei [National Astronomical Observatory of China, CAS, Beijing 100012 (China); Trac, Hy [Harvard-Smithsonian Center for Astrophysics, Harvard University, 60 Garden Street, Cambridge MA 02138 (United States); Cen, Renyue [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2009-10-20

135

Heating the Intergalactic Medium by X-Rays from Population III Binaries in High-redshift Galaxies  

NASA Astrophysics Data System (ADS)

Due to their long mean free path, X-rays are expected to have an important impact on cosmic reionization by heating and ionizing the intergalactic medium (IGM) on large scales, especially after simulations have suggested that Population III (Pop III) stars may form in pairs at redshifts as high as 20-30. We use the Pop III distribution and evolution from a self-consistent cosmological radiation hydrodynamic simulation of the formation of the first galaxies and a simple Pop III X-ray binary model to estimate their X-ray output in a high-density region larger than 100 comoving (Mpc)3. We then combine three different methods—ray tracing, a one-zone model, and X-ray background modeling—to investigate the X-ray propagation, intensity distribution, and long-term effects on the IGM thermal and ionization state. The efficiency and morphology of photoheating and photoionization are dependent on the photon energies. The sub-kiloelectronvolt X-rays only impact the IGM near the sources, while the kiloelectronvolt photons contribute significantly to the X-ray background and heat and ionize the IGM smoothly. The X-rays just below 1 keV are most efficient in heating and ionizing the IGM. We find that the IGM might be heated to over 100 K by z = 10 and the high-density source region might reach 104 K, limited by atomic hydrogen cooling. This may be important for predicting the 21 cm neutral hydrogen signals. On the other hand, the free electrons from X-ray ionizations are not enough to contribute significantly to the optical depth of the cosmic microwave background to the Thomson scattering.

Xu, Hao; Ahn, Kyungjin; Wise, John H.; Norman, Michael L.; O'Shea, Brian W.

2014-08-01

136

The Last Eight-billion Years of Intergalactic Si IV Evolution  

NASA Astrophysics Data System (ADS)

We identified 24 Si IV absorption systems with z <~ 1 from a blind survey of 49 low-redshift quasars with archival Hubble Space Telescope ultraviolet spectra. We relied solely on the characteristic wavelength separation of the doublet to automatically detect candidates. After visual inspection, we defined a sample of 20 definite (group G = 1) and 4 "highly likely" (G = 2) doublets with rest equivalent widths Wr for both lines detected at ? 3{?_{{W_{r}}}}. The absorber line density of the G = 1 doublets was {{{d}}{{N}}_{Si IV}}/{{d}X} = 1.4^{+0.4}_{-0.3} for log N(Si+3)>12.9. The best-fit power law to the G = 1 frequency distribution of column densities f(N(Si+3)) had normalization k = (1.2+0.5 -0.4) × 10-14 cm2 and slope ? N = -1.6+0.3 -0.3. Using the power-law model of f(N(Si+3)), we measured the Si+3 mass density relative to the critical density: {?_{{{Si^{+3}}}}}= (3.7^{+2.8}_{-1.7}) × 10^{-8} for 13 <= log N(Si+3) <= 15. From Monte Carlo sampling of the distributions, we estimated our value to be a factor of 4.8+3.0 -1.9 higher than the 2 <= z <= 4.5 < {?_{{{Si^{+3}}}}}>. From a simple linear fit to {?_{{{Si^{+3}}}}} over the age of the universe, we estimated a slow and steady increase from z = 5.5 ? 0 with {{d}}{?_{{{Si^{+3}}}}}/{{d}}t_age = (0.61± 0.23) × 10^{-8} Gyr^{-1}. We compared our ionic ratios {{N({{Si^{+3}}})}/{N({C^{+3}})}} to a 2 < z < 4.5 sample and concluded, from survival analysis, that the two populations are similar, with median < {{N({{Si^{+3}}})}/{N({C^{+3}})}}> = 0.16.

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

2011-03-01

137

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

E-print Network

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 N_2 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.)?

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

2007-12-10

138

Tomography of the intergalactic medium with Ly? forests in close QSO pairs  

NASA Astrophysics Data System (ADS)

We study the three-dimensional distribution of non-virialized matter at z ~ 2 using high-resolution spectra of quasi-stellar object (QSO) pairs and simulated spectra drawn from cosmological hydrodynamical simulations. We have collected the largest sample of QSO pairs ever observed with Ultraviolet and Visual Echelle Spectrograph (UVES) at the European Southern Observatory-Very Large Telescope (ESO-VLT), with angular separations between ~1 and 14arcmin. The observed correlation functions of the transmitted flux in the HI Lyman ? forest along and transverse to the lines of sight are in good agreement implying that the distortions in redshift space due to peculiar velocities are small. The clustering signal is significant up to velocity separations of ~200kms-1, or about 3h-1 comoving Mpc. The regions at lower overdensity are still clustered but on smaller scales (?v <~ 100kms-1). The observed and simulated correlation functions are compatible at the 3? level. A better concordance is obtained when only the low overdensity regions are selected for the analysis or when the effective optical depth of the simulated spectra is increased artificially, suggesting a deficiency of strong lines in the simulated spectra. We found that also a lower value of the power-law index of the temperature-density relation for the Lyman ? forest gas improves the agreement between observed and simulated results. If confirmed, this would be consistent with other observations favouring a late HeII reionization epoch (at z ~ 3). We remark the detection of a significant clustering signal in the cross-correlation coefficient at a transverse velocity separation ?v? ~ 500kms-1 whose origin needs further investigation. Based on observations collected at the European Southern Observatory Very Large Telescope, Cerro Paranal, Chile - Programs 65.O-0299(A), 68.A-0216(A), 69.A-0204(A), 69.A-0586(A), 70.A-0031(A), 166.A-0106(A). E-mail: dodorico@oats.inaf.it

D'Odorico, V.; Viel, M.; Saitta, F.; Cristiani, S.; Bianchi, S.; Boyle, B.; Lopez, S.; Maza, J.; Outram, P.

2006-11-01

139

The Low-z Intergalactic Medium. II. LyB, OVI, and CIII Forest  

E-print Network

We present the results of a large survey of HI, OVI, and CIII absorption lines in the low-redshift (z80 mA) 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 N_HI and b_HI accurately through a curve-of-growth (COG) analysis. We find that the number of HI absorbers per column density bin is a power-law distribution, dN/dN_HI=N^-beta, with beta_HI=1.68+-0.11. We made 40 detections of OVI 1032,1038 and 30 detections of CIII 977 out of 129 and 148 potential absorbers, respectively. The column density distribution of CIII absorbers has beta_CIII=1.68+-0.04, similar to beta_HI but not as steep as beta_OVI=2.1+-0.1. From the absorption-line frequency, dN_CIII/dz=12^+3_-2 for W(CIII)>30 mA, we calculate a typical IGM absorber size r_0~400 kpc. The COG-derived b-values show that HI samples material with T<10^5 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 OVI and CIII observations with a single phase. The observations require a multiphase IGM in which HI and CIII arise in photoionized regions, while OVI is produced primarily through shocks. From the multiphase ratio N_HI/N_CIII, we infer the IGM metallicity Z_C=0.12 Z_sun, similar to our previous estimate of Z_O=0.09 Z_sun from OVI.

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

2005-12-01

140

THE COLUMN DENSITY DISTRIBUTION AND CONTINUUM OPACITY OF THE INTERGALACTIC AND CIRCUMGALACTIC MEDIUM AT REDSHIFT (z) = 2.4  

SciTech Connect

We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at (z) = 2.4. Using Voigt profile fits to the full Ly{alpha} and Ly{beta} 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{approx}< log (N{sub H{sub I}}/cm{sup -2}){approx}<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{sub H{sub I}} absorbers than low-N{sub H{sub 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{sub H{sub I}}/cm{sup -2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N{sub H{sub I}}/cm{sup -2})>17.2 requires a broken power law parameterization of the frequency distribution with a break near N{sub H{sub I}} Almost-Equal-To 10{sup 15} cm{sup -2}. We compute new estimates of the mean free path ({lambda}{sub mfp}) to hydrogen-ionizing photons at z{sub em} = 2.4, finding {lambda}{sub 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 {lambda}{sub mfp} = 121 {+-} 15 Mpc. These {lambda}{sub mfp} measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z Almost-Equal-To 2-3.

Rudie, Gwen C.; Steidel, Charles C. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Shapley, Alice E. [Department of Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90024 (United States); Pettini, Max, E-mail: gwen@astro.caltech.edu [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

2013-06-01

141

High Resolution Spectroscopy of X-ray Quasars: Searching for the X-ray Absorption from the Warm-Hot Intergalactic Medium  

E-print Network

We present a survey of six low to moderate redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the Warm-Hot Intergalactic Medium. All the X-ray spectra can be fitted by a power law with neutral hydrogen absorption method. The residuals that may caused by additional emission mechanisms or calibration uncertainties are taken account by polynomial in order to search for narrow absorption features. No real absorption line is detected at above 3-sigma level in all the spectra. We discuss the implications of the lack of absorption lines for our understanding of the baryon content of the universe and metallicity of the intergalactic medium (IGM). We find that the non-detection of X-ray absorption lines indicates that the metal abundance of the IGM should be smaller than ~0.3 solar abundance. We also discuss implications of the non-detection of any local (z ~ 0) X-ray absorption associated with the ISM, Galactic halo or local group, such as has been seen along several other lines of sight (LOS). By comparing a pair of LOSs we estimate a lower limit on the hydrogen number density for the (z ~ 0) 3C 273 absorber of n_H >= 4e-3 cm^-3.

Taotao Fang; Claude R. Canizares; Herman L. Marshall

2005-06-06

142

A NEW METHOD TO DIRECTLY MEASURE THE JEANS SCALE OF THE INTERGALACTIC MEDIUM USING CLOSE QUASAR PAIRS  

SciTech Connect

Although the baryons in the intergalactic medium (IGM) trace dark matter fluctuations on megaparsec scales, on smaller scales ?100 kpc, fluctuations are suppressed because the finite temperature gas is pressure supported against gravity, analogous to the classical Jeans argument. This Jeans filtering scale, which quantifies the small-scale structure of the IGM, has fundamental cosmological implications. First, it provides a thermal record of heat injected by ultraviolet photons during cosmic reionization events, and thus constrains the thermal and reionization history of the universe. Second, the Jeans scale determines the clumpiness of the IGM, a critical ingredient in models of cosmic reionization. Third, it sets the minimum mass scale for gravitational collapse from the IGM, and hence plays a pivotal role in galaxy formation. Unfortunately, it is extremely challenging to measure the Jeans scale via the standard technique of analyzing purely longitudinal Ly? forest spectra, because the thermal Doppler broadening of absorption lines along the line-of-sight, is highly degenerate with Jeans smoothing. In this work, we show that the Jeans filtering scale can be directly measured by characterizing the coherence of correlated Ly? forest absorption in close quasar pairs, with separations small enough ?100 kpc to resolve it. We present a novel technique for this purpose, based on the probability density function (PDF) of phase angle differences of homologous longitudinal Fourier modes in close quasar pair spectra. A Bayesian formalism is introduced based on the phase angle PDF, and Markov Chain Monte Carlo techniques are used to characterize the precision of a hypothetical Jeans scale measurement, and explore degeneracies with other thermal parameters governing the IGM. A semi-analytical model of the Ly? forest is used to generate a large grid (500) of thermal models from a dark matter only simulation. Our full parameter study indicates that a realistic sample of only 20 close quasar pair spectra can pinpoint the Jeans scale to ? 5% precision, independent of the amplitude T{sub 0} and slope ? of the temperature-density relation of the IGM T=T{sub 0}(?/ ?-bar ){sup ?-1}. This exquisite sensitivity arises because even long-wavelength one-dimensional Fourier modes ?10 Mpc, i.e., two orders of magnitude larger than the Jeans scale, are nevertheless dominated by projected small-scale three-dimensional (3D) power. Hence phase angle differences between all modes of quasar pair spectra actually probe the shape of the 3D power spectrum on scales comparable to the pair separation. We show that this new method for measuring the Jeans scale is unbiased and is insensitive to a battery of systematics that typically plague Ly? forest measurements, such as continuum fitting errors, imprecise knowledge of the noise level and/or spectral resolution, and metal-line absorption.

Rorai, Alberto; Hennawi, Joseph F. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); White, Martin [Department of Astronomy, University of California at Berkeley, 601 Campbell Hall, Berkeley, CA 94720-3411 (United States)

2013-10-01

143

Space of Spaces  

E-print Network

Wheeler emphasized the study of Superspace - the space of 3-geometries on a spatial manifold of fixed topology. This is a configuration space for GR; knowledge of configuration spaces is useful as regards dynamics and QM.In this Article I consider furthmore generalized configuration spaces to all levels within the conventional `equipped sets' paradigm of mathematical structure used in fundamental Theoretical Physics. This covers A) the more familiar issue of topology change in the sense of topological manifolds (tied to cobordisms), including via pinched manifolds. B) The less familiar issue of not regarding as fixed the yet deeper levels of structure: topological spaces themselves (and their metric space subcase), collections of subsets and sets. Isham has previously presented quantization schemes for a number of these. I consider some classical preliminaries for this program, aside from the most obvious (classical dynamics for each). Rather, I provide I) to all levels Relational and Background Independence criteria, which have Problem of Time facets as consequences. I demonstrate that many of these issues descend all the way down, whilst also documenting at which level the others cease to apply. II) Probability theory on configuration spaces. In fact such a stochastic treatment is how to further mathematize the hitherto fairly formal and sketchy subject of records theory (a type of formultion of quantum gravity). Along these lines I provide a number of further examples of records theories. This is in addition to Kendall's shape statistics being the example corresponding to relational mechanics models. To this example I now add 1) Cech cohomology, 2) Kendall's random sets, 3) the lattice of topologies on a fixed set. I finally consider 4) sheaves, both as a generalization of Cech cohomology and in connection to the study of stratified manifolds such as Superspace itself.

Edward Anderson

2014-11-30

144

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

145

Space Discovery.  

ERIC Educational Resources Information Center

Describes one teacher's experience taking Space Discovery courses that were sponsored by the United States Space Foundation (USSF). These courses examine the history of space science, theory of orbits and rocketry, the effects of living in outer space on humans, and space weather. (DDR)

Blackman, Joan

1998-01-01

146

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

147

Space Shuttle  

NASA Technical Reports Server (NTRS)

The space shuttle flight system and mission profile are briefly described. Emphasis is placed on the economic and social benefits of the space transportation system. The space shuttle vehicle is described in detail.

1976-01-01

148

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

149

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

150

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

151

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

152

Space Day  

NSDL National Science Digital Library

Space Day '98, to be held on May 21, 1998, celebrates and honors the people who have made space exploration possible. The highlight of the Space Day homepage, maintained by Lockheed Martin Corporation, will be a live interactive webcast all day on May 21. Features of the webcast include experts in the fields of space discussing issues ranging from global collaboration to mysteries that remain. In addition to the webcast, the Space Day '98 home page provides resources for teachers and the curious alike. Mission: Fun allows visitors to test their space knowledge through interactive Shockwave games and quizzes while Teachers' Space provides educators with downloadable lesson plans (Adobe Acrobat [.pdf] format).

153

Space prospects. [european space programs  

NASA Technical Reports Server (NTRS)

A strategy for keeping the Common Market's space effort independent of and competitive with NASA and the space shuttle is discussed. Limited financing is the chief obstacle to this. Proposals include an outer space materials processing project and further development of the Ariane rocket. A manned space program is excluded for the foreseeable future.

1980-01-01

154

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

155

Space Shuttle.  

ERIC Educational Resources Information Center

The plans for utilizing reusable space shuttles which could replace almost all present expendable launch vehicles are briefly described. Many illustrations are included showing the artists' concepts of various configurations proposed for space shuttles. (PR)

National Aeronautics and Space Administration, Washington, DC.

156

Space Construction  

NASA Technical Reports Server (NTRS)

The purpose was to present to the aerospace community an in-depth review of Experimental Assembly of Structures on EVA (EASE)/Assembly Concept for Construction of Erectable Space Structures (ACCESS) space flight experiments and to present the status of activities regarding future space flight experiments and accompanying technology developments that will demonstrate the capability of on-orbit construction required for the Space Station.

Hagaman, Jane A. (editor)

1987-01-01

157

Space Update  

NSDL National Science Digital Library

This DVD includes space science images, movies and activities aligned with national standards. Includes the following sections: Astronomy, Solar System, Sky Tonight, and Space Weather models, which run separately or as a linked system, plus Space Events. It is safe for unattended use and suitable for museums or school libraries. Images can be updated without need of an open web browser.

2006-01-01

158

Space Kimchi  

E-print Network

Broadcast Transcript: In space, no one can hear you scream... but did you know that in space no one can detect your smell either? The smell-taste connection means that food in space is not only weightless but tasteless, too. What's a flavor...

Hacker, Randi; Oborny, Jaimie; Tsutsui, William

2006-07-05

159

Multipurpose Spaces.  

ERIC Educational Resources Information Center

This paper examines the emerging trend of multipurpose class spaces, including educational trends influencing multipurpose classroom use, and key issues when using these spaces. Issues discussed include room location, technology integration, food services, acoustics, lighting, outdoor space, capacity, and storage. Design principles emphasized…

Butin, Dan

160

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.

161

Space Law  

NASA Astrophysics Data System (ADS)

This chapter examines the salient characteristics of Space Law. It analyzes the origins and evolution of Space Law, its main international principles, and some current topics of interest to the scientific community: the delimitation of airspace and outer space, intellectual property, and criminal responsibility.

Hermida, Julian

2006-01-01

162

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.

163

$?$--Rindler space  

E-print Network

In this paper we construct, and investigate some thermal properties of, the non-commutative counterpart of Rindler space, which we call $\\kappa$--Rindler space. This space is obtained by changing variables in the defining commutators of $\\kappa$--Minkowski space. We then re-derive the commutator structure of $\\kappa$--Rindler space with the help of an appropriate star product, obtained from the $\\kappa$--Minkowski one. Using this star product, following the idea of Padmanabhan, we find the leading order, $1/\\kappa$ correction to the Hawking thermal spectrum.

J. Kowalski-Glikman

2009-07-18

164

Cognitive Space and Information Space.  

ERIC Educational Resources Information Center

Considers information retrieval systems as a subset of information systems and examines the information spaces of systems and cognitive spaces of users. Presents a method for automatically generating information spaces from document collections that uses term cooccurrence, eigensystems analysis, and Principal Components Analysis, and discusses…

Newby, Gregory B.

2001-01-01

165

Space Carving, Silhouettes Space carving  

E-print Network

Space Carving, Silhouettes #12;Space carving · So far: depth maps · dense reconstruction in form. Seitz #12;Space carving results: Hand Input Image (1 of 100) Views of Reconstruction #12;Silhouette carving #12;Reconstruction from Silhouettes · The case of binary images: a voxel is photo- consistent

Giger, Christine

166

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

167

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

168

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

169

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

170

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

171

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

172

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

173

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

174

On the connection between the intergalactic medium and galaxies: the H I-galaxy cross-correlation at z ? 1  

NASA Astrophysics Data System (ADS)

We present a new optical spectroscopic survey of 1777 `star-forming' (`SF') and 366 `non-star-forming' (`non-SF') galaxies at redshifts z ˜ 0-1 (2143 in total), 22 AGN and 423 stars, observed by instruments such as the Deep Imaging Multi-Object Spectrograph, the Visible Multi-Object Spectrograph and the Gemini Multi-Object Spectrograph, in three fields containing five quasi-stellar objects (QSOs) with Hubble Space Telescope (HST) ultraviolet spectroscopy. We also present a new spectroscopic survey of 173 `strong' (1014 ? NHI? 1017 cm-2) and 496 `weak' (1013 ? NHI < 1014 cm-2) intervening H I (Ly?) absorption-line systems at z ? 1 (669 in total), observed in the spectra of eight QSOs at z ˜ 1 by the Cosmic Origins Spectrograph and the Faint Object Spectrograph on the HST. Combining these new data with previously published galaxy catalogues such as the Very Large Telescope Visible Multi-Object Spectrograph Deep Survey and the Gemini Deep Deep Survey, we have gathered a sample of 654 H I absorption systems and 17 509 galaxies at transverse scales ?50 Mpc, suitable for a two-point correlation function analysis. We present observational results on the H I-galaxy (?ag) and galaxy-galaxy (?gg) correlations at transverse scales r? ? 10 Mpc, and the H I-H I autocorrelation (?aa) at transverse scales r? ? 2 Mpc. The two-point correlation functions are measured both along and transverse to the line of sight, ?(r?, r?). We also infer the shape of their corresponding `real-space' correlation functions, ?(r), from the projected along the line-of-sight correlations, assuming power laws of the form ?(r) = (r/r0)-?. Comparing the results from ?ag, ?gg and ?aa, we constrain the H I-galaxy statistical connection, as a function of both H I column density and galaxy star formation activity. Our results are consistent with the following conclusions: (i) the bulk of H I systems on ˜ Mpc scales have little velocity dispersion (?120 km s-1) with respect to the bulk of galaxies (i.e. no strong galaxy outflow/inflow signal is detected); (ii) the vast majority (˜100 per cent) of `strong' H I systems and `SF' galaxies are distributed in the same locations, together with 75 ± 15 per cent of `non-SF' galaxies, all of which typically reside in dark matter haloes of similar masses; (iii) 25 ± 15 per cent of `non-SF' galaxies reside in galaxy clusters and are not correlated with `strong' H I systems at scales ?2 Mpc; and (iv) >50 per cent of `weak' H I systems reside within galaxy voids (hence not correlated with galaxies), and are confined in dark matter haloes of masses smaller than those hosting `strong' systems and/or galaxies. We speculate that H I systems within galaxy voids might still be evolving in the linear regime even at scales ?2 Mpc.

Tejos, Nicolas; Morris, Simon L.; Finn, Charles W.; Crighton, Neil H. M.; Bechtold, Jill; Jannuzi, Buell T.; Schaye, Joop; Theuns, Tom; Altay, Gabriel; Le Fèvre, Olivier; Ryan-Weber, Emma; Davé, Romeel

2014-01-01

175

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

176

Space suit  

NASA Technical Reports Server (NTRS)

A pressure suit for high altitude flights, particularly space missions is reported. The suit is designed for astronauts in the Apollo space program and may be worn both inside and outside a space vehicle, as well as on the lunar surface. It comprises an integrated assembly of inner comfort liner, intermediate pressure garment, and outer thermal protective garment with removable helmet, and gloves. The pressure garment comprises an inner convoluted sealing bladder and outer fabric restraint to which are attached a plurality of cable restraint assemblies. It provides versitility in combination with improved sealing and increased mobility for internal pressures suitable for life support in the near vacuum of outer space.

Shepard, L. F.; Durney, G. P.; Case, M. C.; Kenneway, A. J., III; Wise, R. C.; Rinehart, D.; Bessette, R. J.; Pulling, R. C. (inventors)

1973-01-01

177

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

178

Space Shuttle  

NASA Technical Reports Server (NTRS)

The design of the spacecraft is described. Focus is placed on the external tanks, the solid rocket boosters, the main engine, and the space shuttle orbiter. The logistics of the project were reviewed and included the management plan, the facilities involved in construction and testing of the space shuttle, and the benefits expected from the project.

1976-01-01

179

Space Telescope.  

ERIC Educational Resources Information Center

This pamphlet describes the Space Telescope, an unmanned multi-purpose telescope observatory planned for launch into orbit by the Space Shuttle in the 1980s. The unique capabilities of this telescope are detailed, the major elements of the telescope are described, and its proposed mission operations are outlined. (CS)

National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

180

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

181

Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for $0 < z < 6$ and the Optical Depth of the Universe to High Energy Gamma-Rays  

Microsoft Academic Search

We calculate the intergalactic photon density as a function of both energy\\u000aand redshift for 0 < z < 6 for photon energies from .003 eV to the Lyman limit\\u000acutoff at 13.6 eV in a Lambda-CDM universe with $\\\\Omega_{\\\\Lambda} = 0.7$ and\\u000a$\\\\Omega_{m} = 0.3$. Our galaxy evolution model gives results which are\\u000aconsistent with Spitzer deep number counts

F. W. Stecker; M. A. Malkan; S. T. Scully

2005-01-01

182

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

183

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

184

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

185

Echelle Spectroscopy of a Gamma-Ray Burst Afterglow at z = 3.969: A New Probe of the Interstellar and Intergalactic Media in the Young Universe  

NASA Astrophysics Data System (ADS)

We present an echelle spectrum of the Swift GRB 050730, obtained 4 hr after the burst using the MIKE spectrograph on the Magellan Clay telescope when the afterglow was at R=17.7. The spectrum reveals a forest of absorption features superposed on a simple power-law shaped continuum, best described as f?(?)~?? with ?=1.88+/-0.01 over ?=7000-9000 Å. We identify the gamma-ray burst (GRB) host at zGRB=3.96855 based on the hydrogen Lyman absorption series, narrow absorption lines due to heavy ions such as O I, C II, Si II, S II, Ni II, Fe II, C IV, Si IV, and N V, and fine-structure transitions such as O I*, O I**, Si II*, C II*, and Fe II*. Together these transitions allow us to study the properties of the interstellar medium (ISM) in the GRB host. The principal results are as follows. (1) We estimate a neutral hydrogen column density of logN(H I)=22.15+/-0.05 in the host. (2) The associated metal lines exhibit multiple components over a velocity range of ~80 km s-1, with >90% of the neutral gas confined in 20 km s-1. (3) Comparisons between different ionic transitions show that the host has little or no dust depletion and has 1/100 solar metallicity. (4) The absorbing gas has much higher density than that of intervening damped Ly? absorption (DLA) systems. In addition, we report the identification of an intervening DLA system at zDLA=3.56439 with logN(H I)=20.3+/-0.1 and <5% solar metallicity, a Lyman limit system at zLLS=3.02209 with logN(H I)=19.9+/-0.1, a strong Mg II absorber at zMgII=2.25313, and a pair of Mg II absorbers at zMgII=1.7731, 57 km s-1 apart. We demonstrate that rapid echelle spectroscopy of GRB afterglows helps to reveal a wealth of information in the ISM and the intergalactic medium along the sight line, which, when followed up with late-time deep imaging, will allow us to uncover a sample of distant galaxies with known ISM properties to constrain galaxy formation models.

Chen, Hsiao-Wen; Prochaska, Jason X.; Bloom, Joshua S.; Thompson, Ian B.

2005-11-01

186

Chandra View of the Warm-hot Intergalactic Medium toward 1ES 1553+113: Absorption-line Detections and Identifications. I.  

NASA Astrophysics Data System (ADS)

We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z >~ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2? and 4.1?. Six of these lines are detected at high single-line statistical significance (3.6 <= ? <= 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z ~= 0, and we identify them with Galactic O I and C II. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV H I and/or O VI intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1?, 4.1?, 3.9?, 3.8?, and 2.7?), are identified as C V and C VI K? absorbers belonging to three WHIM systems at zX = 0.312, zX = 0.237, and langzX rang = 0.133, which also produce broad H I (and O VI for the zX = 0.312 system) absorption in the FUV. For two of these systems (zX = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad H I associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy for WHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8? (zX = 0.312; 6.3? if the low-significance O V and C V K? associations are considered), 3.9? (zX = 0.237), and 3.8? (langzX rang = 0.133), respectively.

Nicastro, F.; Elvis, M.; Krongold, Y.; Mathur, S.; Gupta, A.; Danforth, C.; Barcons, X.; Borgani, S.; Branchini, E.; Cen, R.; Davé, R.; Kaastra, J.; Paerels, F.; Piro, L.; Shull, J. M.; Takei, Y.; Zappacosta, L.

2013-06-01

187

Space education  

NASA Astrophysics Data System (ADS)

An essential pre-requisite to a successful space technology applications programme is the building of various indigenous capacities, particularly human resources. Efforts to accomplish such a capacity-building must be devoted, at the local level, to the development of necessary high-level knowledge and expertise in space science and technology fields. Such a programme must also focus on long-term in-depth education and research opportunities in the developing countries, where the beneficiaries would gain an in-depth understanding and appreciation of not only the application potentials of a given technology but also an insight into why and how the technology works the way it does. In recognition of such a pre-requisite, it is universally acknowledged that if effective assimilation of space science and appropriate application of space technology are to succeed in the developing countries, and particularly if such a discipline as satellite remote sensing is to transcend its current image of being a technology-driven tool into a user-driven one, efforts must be devoted, at the local level, to the development of necessary high-level knowledge and expertise in requisite space science and technology fields. The justification for such an in-depth education is not far-fetched particularly as one reflects on the myriad of space science and technology activities that are both in progress and are planned. Aspects of these are reflected in this paper.

Abiodun, Adigun Ade

188

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

189

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

190

Space.com - Space TV  

NSDL National Science Digital Library

At this site, users can view and download videos on a variety of space-related topics including exploration, astronomy, the Earth, historic moments in exploration, and the search for extraterrestrial life.

191

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.

192

Space Alive  

NASA Astrophysics Data System (ADS)

This paper looks at earthly architectural applications of scientific research on space orientation in reduced gravity conditions. It asks how unprecedented forms of perception experienced in reduced gravity conditions give rise to unconventional modes of living. Looking at different technical lineages for achieving weightlessness: on the one hand, outer space exploration and its habitats, and on the other, technologies of suspension associated with experimental architecture, it questions the pragmatics of exchangeability between art and science. Instead of insisting on systems of valuation, that is, instead of opposing the functionality of outer space habitats with the aesthetic of experimental architecture, both practices will be approached in their own terms and on their terrain, that is, in the pragmatics of their effectiveness.

Boucher, M.-P.

2014-04-01

193

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

194

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

195

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

196

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

197

Space Toxicology  

NASA Technical Reports Server (NTRS)

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 propellants, excess offgassing from polymeric materials, leakage of systems compounds, escape of payload compounds, over-use of utility compounds, microbial metabolism, and human metabolism. The toxicological risk posed by a compound is comprised of the probability of escaping to cause air pollution and the magnitude of adverse effects on human health if escape occurs. The risk from highly toxic compounds is controlled by requiring multiple levels of containment to greatly reduce the probability of escape; whereas compounds that are virtually non-toxic may require little or no containment. The potential for toxicity is determined by the inherent toxicity of the compound and the amount that could potentially escape into the breathing air.

James, John T.

2011-01-01

198

Southern Spaces  

NSDL National Science Digital Library

Exploring the American South is a splendid idea, and this online journal is a great way to think about the "real and imagined places" of this unique cultural region. Southern Spaces is a peer-reviewed Internet journal and forum that "provides open access to essays, interviews and performances, events and conferences, gateways, timescapes, and annotated links about real and imagined spaces and places of the U.S. South." Their work is supported by the Robert W. Woodruff Library of Emory University, and visitors will want to browse around the site more than once. First-time visitors may wish to start by looking at interactive features like "Negotiating Gender Lines: Women's Movement across Atlanta Mosques" and "The Other Side of Paradise: Glimpsing Slavery in the University's Utopian Landscapes". The site also includes information about the journal's editorial board and a set of thematically organized weblinks.

199

[Space diet].  

PubMed

Food prepared for astronauts meets various physical and biological requirements determined by living conditions in a space environment. Onboard systems, work programs, launch costs impose weight and volume limitations. For all investigated food items, the manufacturing technique must take into account all flight specific mechanical parameters. From a nutrition and sanitation standpoint, food packs must be designed to comply with certain specific effects of long term flights ans selected food items must be thoroughly safe, which requires very strict laboratory testing. The diet must also be varied, if possible it should match astronauts' personal preferences. Food preparations must be easy to use. Space food items are original applications of existing technologies: they are of very high quality. PMID:2598067

Luigi, R

1989-06-01

200

Open Spaces  

NSDL National Science Digital Library

Featuring articles by leading experts on topics from science policy to ecology (such as Bruce Babbitt and Jane Lubchenko), this new publication from Portland, Oregon attempts to incorporate synthetic, broad perspectives with a host of (familiar) environmental topics. A subscription fee is required to access all articles at the Open Spaces Website, but several interesting sample articles are currently posted for free online viewing. Science writers and scientists interested in widening their perspectives will find this an intriguing resource.

201

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. PMID:24005797

Coiera, Enrico

2014-01-01

202

Sobolev spaces  

Microsoft Academic Search

i.j=l a~i Oxj Oxi it is clear that Vu c L 2 and u e L 2 are sufficient conditions for the integrals to be well-defined. In addition, when you seek to minimize the functional thus arising (Dirichlet's principle for the Laplacian), they are the natural complete spaces to which the sought after minimizers belong. This allows existence to be

Raymond Johnson; V. G. Maz; T. O. Shaposhnikova

1987-01-01

203

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

204

46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Hold space, void space, cofferdam, and spaces containing...Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam, and spaces...

2011-10-01

205

46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Hold space, void space, cofferdam, and spaces containing...Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam, and spaces...

2012-10-01

206

46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Hold space, void space, cofferdam, and spaces containing...Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam, and spaces...

2010-10-01

207

46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.  

Code of Federal Regulations, 2014 CFR

... 2014-10-01 false Hold space, void space, cofferdam, and spaces containing...Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam, and spaces...

2014-10-01

208

46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Hold space, void space, cofferdam, and spaces containing...Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam, and spaces...

2013-10-01

209

Space Radiation  

NASA Technical Reports Server (NTRS)

Astronauts receive the highest occupational radiation exposure. Effective protections are needed to ensure the safety of astronauts on long duration space missions. Increased cancer morbidity or mortality risk in astronauts may be caused by occupational radiation exposure. Acute and late radiation damage to the central nervous system (CNS) may lead to changes in motor function and behavior, or neurological disorders. Radiation exposure may result in degenerative tissue diseases (non-cancer or non-CNS) such as cardiac, circulatory, or digestive diseases, as well as cataracts. Acute radiation syndromes may occur due to occupational radiation exposure.

Wu, Honglu

2006-01-01

210

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

211

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).

212

An Evolvable Space Telescope for NASA’s Next UVOIR Flagship Mission  

NASA Astrophysics Data System (ADS)

NASA has sponsored several studies to develop conceptual designs for the next UVOIR Flagship mission, including an Advanced Technology Large Space Telescope (ATLAST). These studies concluded that a space observatory launched in ~2030 will require a telescope aperture of 8 to 16 meters to address the most compelling astrophysical questions raised by missions such as HST, Kepler, TESS, JWST and WFIRST as well as the large ground based telescopes that will coming on-line in the next decade. This telescope will be designed to search for the bio-signatures of life in the universe as well as to study the physics of star formation and to unravel the complex interactions between dark matter, galaxies and the intergalactic medium.Unfortunately, telescopes with this aperture will have a long development time with peak funding requirements that will absorb most NASA's Astrophysics budget for many years. To minimize this impact on NASA's budget and to drastically shorten the time between program start and 'first light' for this UVOIR space observatory we have been developing conceptual designs for an Evolvable Space Telescope (EST) that would be assembled on-orbit in three stages, beginning with the launch of a 2 mirror 4 x 12 meter telescope with 2 instruments 5 to 7 years after program start, and then adding mirror segments and instruments ay ~ 5 year intervals to obtain a 12-m filled aperture, and then a 20-m filled aperture telescope. We describe our approach in this presentation.

Lillie, Charles F.; Breckinridge, James B.; MacEwen, Howard A.; Polidan, Ronald S.; Flannery, Martin; Dailey, Dean

2015-01-01

213

Dust in the planetary system: Dust interactions in space plasmas of the solar system  

NASA Astrophysics Data System (ADS)

Cosmic dust particles are small solid objects observed in the solar planetary system and in many astronomical objects like the surrounding of stars, the interstellar and even the intergalactic medium. In the solar system the dust is best observed and most often found within the region of the orbits of terrestrial planets where the dust interactions and dynamics are observed directly from spacecraft. Dust is observed in space near Earth and also enters the atmosphere of the Earth where it takes part in physical and chemical processes. Hence space offers a laboratory to study dust-plasma interactions and dust dynamics. A recent example is the observation of nanodust of sizes smaller than 10 nm. We outline the theoretical considerations on which our knowledge of dust electric charges in space plasmas are founded. We discuss the dynamics of the dust particles and show how the small charged particles are accelerated by the solar wind that carries a magnetic field. Finally, as examples for the space observation of cosmic dust interactions, we describe the first detection of fast nanodust in the solar wind near Earth orbit and the first bi-static observations of PMSE, the radar echoes that are observed in the Earth ionosphere in the presence of charged dust.

Mann, Ingrid; Meyer-Vernet, Nicole; Czechowski, Andrzej

2014-03-01

214

Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope  

E-print Network

We discuss new constraints on the epoch of cosmic reionization and test the assumption that most of the ionizing photons responsible arose from high redshift star-forming galaxies. Good progress has been made in charting the end of reionization through spectroscopic studies of z~6-8 QSOs, gamma-ray bursts and galaxies expected to host Lyman-alpha emission. However, the most stringent constraints on its duration have come from the integrated optical depth, tau, of Thomson scattering to the cosmic microwave background. Using the latest data on the abundance and luminosity distribution of distant galaxies from Hubble Space Telescope imaging, we simultaneously match the reduced value tau=0.066 +/- 0.012 recently reported by the Planck collaboration and the evolving neutrality of the intergalactic medium with a reionization history within 6 >10) galaxies. Our analysis strengthens the conclusion that star-forming galaxies dominated the reionization process and has important implications for upcoming 21cm experiment...

Robertson, Brant E; Furlanetto, Steven R; Dunlop, James S

2015-01-01

215

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

216

Space teleoperations technology for Space Station evolution  

Microsoft Academic Search

Viewgraphs on space teleoperations technology for space station evolution are presented. Topics covered include: shuttle remote manipulator system; mobile servicing center functions; mobile servicing center technology; flight telerobotic servicer-telerobot; flight telerobotic servicer technology; technologies required for space station assembly; teleoperation applications; and technology needs for space station evolution.

Gerald J. Reuter

1990-01-01

217

UNIVERSITY SPACE POLICY ALLOCATION OF UNIVERSITY SPACE  

E-print Network

. Hereto, space has usually been allocated in an ad hoc manner on a long term basis without periodic reviewUNIVERSITY COLLEGE DUBLIN UNIVERSITY SPACE POLICY #12;ALLOCATION OF UNIVERSITY SPACE I Purpose To provide a methodology for the allocation of space across the University II Background Due

218

COMMERCIAL SPACE ACCOMPLISHMENTS Commercial Cargo Space Accomplishments  

E-print Network

to the International Space Station (ISS), bringing this important work back to the United States where it belongs requirements for transporting NASA's crew to the International Space Station. Unfunded Space Act Agreements by the extension of International Space Station operations to 2020, enabling expanded commercial and research

Waliser, Duane E.

219

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

220

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

221

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

222

Preparing future space leaders - International Space University  

NASA Technical Reports Server (NTRS)

The International Space University (ISU) concept of developing a cadre of space professionals that will lead the universities and industries into space is discussed. ISU is an innovative, permanent worldwide organization for training and academic instruction in all aspects of space studies. ISU's major goal is to provide the young professional academic instruction in technical and nontechnical areas of modern space exploration and research, and a forum to exchange ideas and develop both personal and professional ties at an international level.

Stone, Barbara A.; Van Reeth, George P.

1992-01-01

223

"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

224

Space Transportation: Marshall Space Flight Center  

NSDL National Science Digital Library

NASA's Marshall Space Flight Center is the location of an ongoing initiative to make access to space easier and more affordable. The center conducts extensive space propulsion research; four focus areas include advanced chemical propulsion, plasma propulsion, high-powered electrical propulsion, and propellantless propulsion. There is also a lot of information about the Integrated Space Transportation System and the Space Launch Initiative, which mainly deal with reusable launch vehicles (RLV). The space shuttle is the first generation RLV; second and third generation RLVs aim to increase safety while dramatically lowering launch costs.

225

1 Gravier Garage -581 spaces 2 1542 Garage -75 spaces  

E-print Network

1 Gravier Garage - 581 spaces 2 1542 Garage - 75 spaces 3 Lakeside Lot - 24 spaces 4 I-10 Lot #1 - 65 spaces 5 I-10 Lot #2 - 28 spaces 6 I-10 Lot #3 - 74 spaces 7 Perdido (440) Lot - 232 spaces 8 Student Lot #2 - 281 spaces 9 Student Lot #3 - 245 spaces 10 Student Lot #1 - 117 spaces 11 Residence Hall

226

1 Gravier Garage -581 spaces 2 1542 Garage -75 spaces  

E-print Network

1 Gravier Garage - 581 spaces 2 1542 Garage - 75 spaces 3 Lakeside Lot - 24 spaces 4 I-10 Lot #1 - 65 spaces 5 I-10 Lot #2 - 28 spaces 6 I-10 Lot #3 - 74 spaces 7 Perdido (440) Lot - 157 spaces 8 Student Lot #2 - 281 spaces 9 Student Lot #3 - 245 spaces 10 Student Lot #1 - 117 spaces 11 Residence Hall

227

SPACE FOR INNOVATION (OR INNOVATION FOR SPACE)  

E-print Network

at NASA ­ Lessons from Silicon Valley · Space for innovation ­ Opportunities in Iceland · Space! #12;www.hr.is Three Examples #12;www.hr.is Lessons from Silicon Valley · What makes Silicon Valley so

Karlsson, Brynjar

228

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

229

Definitions Numbered Space  

E-print Network

Definitions · Numbered Space ­ a single space marked with a number and reserved for a single permit 24/7 · Unnumbered Space ­ a space which can be used by any customer allowed to park in that lot. High Low Average Question 4: If I buy a staff permit for an UNNUMBERED* space in a non-gated surface

Behmer, Spencer T.

230

CRYSTALLOGRAPHIC POINT AND SPACE  

E-print Network

CRYSTALLOGRAPHIC POINT AND SPACE GROUPS Andy Elvin June 10, 2013 #12;Contents Point and Space no reflection axes #12;Cube and Octahedron are dual Symmetries under Oh #12;Space Groups Subgroups of E(3) Point Group + Translation { R | 0 }{ E | t }a = { R | t }a = Ra + t 230 Space Groups 73 symmorphic space

California at Santa Cruz, University of

231

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

232

Space Flight. Teacher Resources.  

ERIC Educational Resources Information Center

This teacher's guide contains information, lesson plans, and diverse student learning activities focusing on space flight. The guide is divided into seven sections: (1) "Drawing Activities" (Future Flight; Space Fun; Mission: Draw); (2) "Geography" (Space Places); (3) "History" (Space and Time); (4) "Information" (Space Transportation System;…

2001

233

Space superiority: a call to space warriors  

Microsoft Academic Search

This essay1 discusses the importance of developing space superiority campaigns for future warfare success. It provides strategists with a coercion theory-based conceptual framework to provide a broader range of coercion mechanisms than has traditionally been offered. To selectively neutralize space systems, space strategists must move beyond the Cold War's spacecraft destruction-only focus and employ space superiority campaigns composed of a

C. A. S. McKintey

1997-01-01

234

Life in Space: The International Space Station  

NSDL National Science Digital Library

Students are introduced to the International Space Station (ISS) with information about its structure, operation and key experiments. The ISS itself is an experiment in international cooperation to explore the potential for humans to live in space. The space station features state-of-the-art science and engineering laboratories to conduct research in medicine, materials and fundamental science to benefit people on Earth as well as people who will live in space in the future.

Integrated Teaching And Learning Program

235

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

236

The partnership: Space shuttle, space science, and space station  

NASA Technical Reports Server (NTRS)

An overview of the NASA Space Station Program functions, design, and planned implementation is presented. The discussed functions for the permanently manned space facility include: (1) development of new technologies and related commercial products; (2) observations of the Earth and the universe; (3) provision of service facilities for resupply, maintenance, upgrade and repair of payloads and spacecraft; (4) provision of a transportation node for stationing, processing and dispatching payloads and vehicles; (5) provision of manufacturing and assembly facilities; (6) provision of a storage depot for parts and payloads; and (7) provision of a staging base for future space endeavors. The fundamental concept for the Space Station, as given, is that it be designed, operated, and evolved in response to a broad variety of scientific, technological, and commercial user interests. The Space Shuttle's role as the principal transportation system for the construction and maintenance of the Space Station and the servicing and support of the station crew is also discussed.

Culbertson, Philip E.; Freitag, Robert F.

1989-01-01

237

Sculpting space through sound  

E-print Network

How does one experience space? What kind of information do humans collect in the process of constructing space in their mind? How does one begin to understand volume, light, texture, material, smell and sense of space? The ...

Nakagawa, Junko, 1975-

2002-01-01

238

Quantum Complex Minkowski Space  

E-print Network

The complex Minkowski phase space has the physical interpretation of the phase space of the scalar massive conformal particle. The aim of the paper is the construction and investigation of the quantum complex Minkowski space.

Grzegorz Jakimowicz; Anatol Odzijewicz

2005-05-06

239

Space.com  

NSDL National Science Digital Library

Space.com is an online forum for discussion of space, science and technological innovation. It has links to online magazines like Live Science, Space News, and Ad Astra, SETI science and provides a community bulletin board.

2005-04-25

240

Space Probe Launch  

NASA Technical Reports Server (NTRS)

Managed by Marshall Space Flight Center, the Space Tug was a reusable multipurpose space vehicle designed to transport payloads to different orbital inclinations. Utilizing mission-specific combinations of its three primary modules (crew, propulsion, and cargo) and a variety of supplementary kits, the Space Tug was capable of numerous space applications. This 1970 artist's concept depicts the Tug's propulsion module launching a space probe into lunar orbit.

1970-01-01

241

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

242

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

243

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes  

NASA Technical Reports Server (NTRS)

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts 2x3, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>lO, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (<50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems.

Gardner, Jonathan P.

2007-01-01

244

Studying Galaxy Formation and Reionization with the James Webb Space Telescope  

NASA Technical Reports Server (NTRS)

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z>6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (<50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. I will review the current status of the project.

Gardner, Jonathan P.

2008-01-01

245

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes  

NASA Technical Reports Server (NTRS)

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z greater than 6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z greater than 10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (less than 50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth-Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems, and discuss recent progress in constructing the observatory.

Gardner, Jonathan P.

2009-01-01

246

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes  

NASA Technical Reports Server (NTRS)

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts z>6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (<50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. In addition to JWST's ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems.

Gardner, Jonathan P.

2007-01-01

247

Studying Galaxy Formation with the Hubble, Spitzer and James Webb Space Telescopes  

NASA Technical Reports Server (NTRS)

The deepest optical to infrared observations of the universe include the Hubble Deep Fields, the Great Observatories Origins Deep Survey and the recent Hubble Ultra-Deep Field. Galaxies are seen in these surveys at redshifts 2-6, less than 1 Gyr after the Big Bang, at the end of a period when light from the galaxies has reionized Hydrogen in the inter-galactic medium. These observations, combined with theoretical understanding, indicate that the first stars and galaxies formed at z>10, beyond the reach of the Hubble and Spitzer Space Telescopes. To observe the first galaxies, NASA is planning the James Webb Space Telescope (JWST), a large (6.5m), cold (50K), infrared-optimized observatory to be launched early in the next decade into orbit around the second Earth- Sun Lagrange point. JWST will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 27 microns. In addition to JWST s ability to study the formation and evolution of galaxies, I will also briefly review its expected contributions to studies of the formation of stars and planetary systems.

Gardner, Jonathan F.; Barbier, L. M.; Barthelmy, S. D.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Hullinger, D. D.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; Sakamoto, T.

2006-01-01

248

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

249

Benefits Stemming from Space Exploration  

E-print Network

Benefits Stemming from Space Exploration September 2013 International Space from Space Exploration Table of Content Executive Summary .......................................................................................................................................... 3 2. Fundamental Benefits of Space Exploration

Waliser, Duane E.

250

Space vehicle propulsion systems: Environmental space hazards  

NASA Technical Reports Server (NTRS)

The hazards that exist in geolunar space which may degrade, disrupt, or terminate the performance of space-based LOX/LH2 rocket engines are evaluated. Accordingly, a summary of the open literature pertaining to the geolunar space hazards is provided. Approximately 350 citations and about 200 documents and abstracts were reviewed; the documents selected give current and quantitative detail. The methodology was to categorize the various space hazards in relation to their importance in specified regions of geolunar space. Additionally, the effect of the various space hazards in relation to spacecraft and their systems were investigated. It was found that further investigation of the literature would be required to assess the effects of these hazards on propulsion systems per se; in particular, possible degrading effects on exterior nozzle structure, directional gimbals, and internal combustion chamber integrity and geometry.

Disimile, P. J.; Bahr, G. K.

1990-01-01

251

In Outer Space without a Space Suit?  

E-print Network

The author proposes and investigates his old idea - a living human in space without the encumbrance of a complex space suit. Only in this condition can biological humanity seriously attempt to colonize space because all planets of Solar system (except the Earth) do not have suitable atmospheres. Aside from the issue of temperature, a suitable partial pressure of oxygen is lacking. In this case the main problem is how to satiate human blood with oxygen and delete carbonic acid gas (carbon dioxide). The proposed system would enable a person to function in outer space without a space suit and, for a long time, without food. That is useful also in the Earth for sustaining working men in an otherwise deadly atmosphere laden with lethal particulates (in case of nuclear, chemical or biological war), in underground confined spaces without fresh air, under water or a top high mountains above a height that can sustain respiration.

Alexander Bolonkin

2008-06-24

252

Space Toxicology: Human Health during Space Operations  

NASA Technical Reports Server (NTRS)

Space Toxicology is a unique and targeted discipline for spaceflight, space habitation and occupation of celestial bodies including planets, moons and asteroids. Astronaut explorers face distinctive health challenges and limited resources for rescue and medical care during space operation. A central goal of space toxicology is to protect the health of the astronaut by assessing potential chemical exposures during spaceflight and setting safe limits that will protect the astronaut against chemical exposures, in a physiologically altered state. In order to maintain sustained occupation in space on the International Space Station (ISS), toxicological risks must be assessed and managed within the context of isolation continuous exposures, reuse of air and water, limited rescue options, and the need to use highly toxic compounds for propulsion. As we begin to explore other celestial bodies in situ toxicological risks, such as inhalation of reactive mineral dusts, must also be managed.

Khan-Mayberry, Noreen; James, John T.; Tyl, ROchelle; Lam, Chiu-Wing

2010-01-01

253

Budgeting Academic Space  

ERIC Educational Resources Information Center

There are many articles about space management, including those that discuss space calculations, metrics, and categories. Fewer articles discuss the space budgeting processes used by administrators to allocate space. The author attempts to fill this void by discussing her administrative experiences with Middle Tennessee State University's (MTSU)…

Harris, Watson

2011-01-01

254

On War in Space  

Microsoft Academic Search

Earth orbital space is a militarily and economically critical arena to the U.S. While space has never been forcibly contested to date, this initial period of coincidental quiescence is coming to an end. A growing number of states are developing the means with which not merely to access and exploit space, but to conduct space warfare as well. The time

Howard Kleinberg

2007-01-01

255

Space Complexity Algorithms & Complexity  

E-print Network

Space Complexity Algorithms & Complexity Space Complexity Nicolas Stroppa Patrik Lambert - plambert@computing.dcu.ie CA313@Dublin City University. 2008-2009. December 4, 2008 #12;Space Complexity Hierarchy of problems #12;Space Complexity NP-intermediate Languages If P = NP, then are there languages which neither in P

Way, Andy

256

Space Shuttle Program Status  

E-print Network

1 Space Shuttle Program Status John Casper Associate Manager Space Shuttle Program September 13, 2010 NAC Space Operations Committee #12;2 Operations #12;3 Flown Manifest March 2009 ­ May 2010 #12, 2010 · 132nd Space Shuttle mission · 32nd Flight of Atlantis (120,650,907 statute miles) · 294 Total

Waliser, Duane E.

257

Using space resources  

NASA Technical Reports Server (NTRS)

The topics covered include the following: reducing the cost of space exploration; the high cost of shipping; lunar raw materials; some useful space products; energy from the moon; ceramic, glass, and concrete construction materials; mars atmosphere resources; relationship to the Space Exploration Initiative (SEI); an evolutionary approach to using space resources; technology development; and oxygen and metal coproduction.

Sullivan, Thomas A.; Mckay, David S.

1991-01-01

258

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.

259

SPACE RESOURCES ROUNDTABLE IX  

E-print Network

L@umr.edu Announcements and Logistics: Office of Special Programs & Continuing Education (SPACE) space@mines.edu #12, natural resources industry personnel (mining, quarrying, construction), and entrepreneurs interested utilizing space resources. · Market demand and utilization scenarios for space resources and their products

Rathbun, Julie A.

260

NEXT GENERATION SPACE TELESCOPE  

E-print Network

the Early Universe: The Dark Ages . . . . . . . . . . . . .1 2 Seeing Beyond the Hubble Space Telescope the feasibility of a large aperture space telescope to follow the Hubble Space Telescope. The scientific goalsTHE NEXT GENERATION SPACE TELESCOPE Visiting a Time When Galaxies Were Young The NGST Study Team

Sirianni, Marco

261

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

262

Sustaining humans in space  

NASA Technical Reports Server (NTRS)

NASA research on the functioning of biological systems in space and the resulting improvement in space suits and life-support systems is discussed. The centrifuge facility which will provide the major elements of a life science research facility for Spacelab and Space Station Freedom is described, and the Vestibular Research Facility for studying motion sickness in space is examined. The aluminum AX-5 space suit and the Controlled Ecological Life-Support System are described, and biomedical sensors for studying bone mass changes in space are discussed. Studies on the use of exercise to control tissue-fluid shifts in space are described.

Hubbard, G. Scott; Hargens, Alan R.

1989-01-01

263

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

264

Destination Outer Space  

NSDL National Science Digital Library

Students acquire a basic understanding of the science and engineering of space travel as well as a brief history of space exploration. They learn about the scientists and engineers who made space travel possible and briefly examine some famous space missions. Finally, they learn the basics of rocket science (Newton's third law of motion), the main components of rockets and the U.S. space shuttle, and how engineers are involved in creating and launching spacecraft.

Integrated Teaching And Learning Program

265

A generalized perceptual space.  

PubMed

Based upon experimental results on certain visual spatial discrimination tasks, we have developed a formalism for a non-Euclidian perceptual space. In this formalism, the transformation from real to perceptual space is given by a generalized covariant tensor. The concept of parallel transport of vectors in a curved space is used to prove that closed loops in real space imply closed loops with the same orientation in the perceptual space also. PMID:11091975

Lakshminarayanan, V; Parthasarathy, R; DeValois, K K

2000-10-01

266

National Aeronautics and Space Administration Space Launch System Status  

E-print Network

Authorization Act of 2010 ­ Section 302 Space Launch System as Follow-on Launch Vehicle to the Space Shuttle (a-on to the Space Shuttle that can access cis- lunar space and the regions of space beyond low-Earth orbit in orderNational Aeronautics and Space Administration Space Launch System Status Briefing to NAC Space

Waliser, Duane E.

267

Patchy intergalactic He II absorption in HE 2347-4342. II. The possible discovery of the epoch of He-reionization  

NASA Astrophysics Data System (ADS)

We report on observations of redshifted Heii303.8 Angstroms absorption in the high-redshift QSO HE2347-4342 (z=2.885, V=16.1) with the Goddard High Resolution Spectrograph on board HST in its low resolution mode (bigtriangleup lambda = 0.7 Angstroms). With f_?=3.6\\ 10(-15) ergcm(-2) s(-1) Angstroms(-1) at the expected position of Heii304 Angstroms absorption it is the most UV-bright high redshift QSO discovered so far. We show that the Heii opacity as a function of redshift is patchy showing spectral regions with low Heii opacity (``voids'') and regions with high Heii opacity (blacked-out ``troughs'') and no detectable flux. Combination with high-resolution optical spectra of the Lyalpha forest using CASPEC at the 3.6m telescope shows that the voids can be explained either exclusively by Lyalpha forest cloud absorption with a moderate N_{subs {He{sc ii}}}/N_{subs {H{sc i}}} ratio eta <=100 and turbulent line broadening or by a combination of Lyalpha forest with eta = 45 and thermal broadening plus a diffuse medium with tau_ {subs {GP}}({subs {He{sc ) ii}}} ~ 0.3. Since the latter is a minimum assumption for the Lyalpha forest, a strict upper limit to a diffuse medium is Omega_ {subs {diff}}<0.02 h50(-1.5) at z=2.8. In the troughs in addition to the Lyalpha forest opacity a continuous Heii 304 Angstroms opacity tau = 4.8(+infty }_{-2) is required. In case of photoionization, the troughs would require a diffuse component with a density close to Omega =~ 0.077(eta /45)(-0.5) h50(-1.5) , i.e. all baryons in the universe, which is inconsistent, however, with the observed absence of such a component in the voids. A tentative interpretation is that we observe the epoch of partial Heii reionization of the universe with patches not yet reionized. In that case a diffuse component with Omega_ {subs {diff}}>= 1.3\\ 10(-4) h(-1}_{50) would be sufficient to explain the ``trough'' opacity. The size of the 1163--1172 Angstroms trough is ~ 6 h50(-1) Mpc or ~ 2300 kms(-1) , respectively. We also discuss partially resolved Heii absorption of a high-ionization associated absorption system. Despite its high luminosity HE2347-4342 does not show a Heii proximity effect. A possible reason is that the strong associated system shields the Heii ionizing continuum. Based on observations collected at the European Southern Observatory, La Silla, Chile (ESO No.\\ 58.B--0116). Based on IUE observations collected at the ESA VILSPA ground station near Madrid, Spain. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by Aura, Inc., under NASA contract NAS 5--26\\,555.

Reimers, D.; Kohler, S.; Wisotzki, L.; Groote, D.; Rodriguez-Pascual, P.; Wamsteker, W.

1997-11-01

268

Space Math: Mathematics in Space Science III  

NSDL National Science Digital Library

This booklet contains 36 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 applications of arithmetic, graph analysis, pre-algebra, and algebra.

Odenwald, Sten

2007-01-01

269

Space Math: Mathematics in Space Science II  

NSDL National Science Digital Library

This booklet contains 36 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.

Odenwald, Sten

2007-01-01

270

Esrange Space Center, a Gate to Space  

NASA Astrophysics Data System (ADS)

Swedish Space Corporation (SSC) is operating the Esrange Space Center in northern Sweden. Space operations have been performed for more than 40 years. We have a unique combination of maintaining balloon and rocket launch operations, and building payloads, providing space vehicles and service systems. Sub-orbital rocket flights with land recovery and short to long duration balloon flights up to weeks are offered. The geographical location, land recovery area and the long term experience makes Swedish Space Corporation and Esrange to an ideal gate for space activities. Stratospheric balloons are primarily used in supporting atmospheric research, validation of satellites and testing of space systems. Balloon operations have been carried out at Esrange since 1974. A large number of balloon flights are yearly launched in cooperation with CNES, France. Since 2005 NASA/CSBF and Esrange provide long duration balloon flights to North America. Flight durations up to 5 days with giant balloons (1.2 Million cubic metres) carrying heavy payload (up to 2500kg) with astronomical instruments has been performed. Balloons are also used as a crane for lifting space vehicles or parachute systems to be dropped and tested from high altitude. Many scientific groups both in US, Europe and Japan have indicated a great need of long duration balloon flights. Esrange will perform a technical polar circum balloon flight during the summer 2008 testing balloon systems and flight technique. We are also working on a permission giving us the opportunity on a circular stratospheric balloon flight around the North Pole.

Widell, Ola

271

Space Station Power System  

NASA Technical Reports Server (NTRS)

The strategies, reasoning, and planning guidelines used in the development of the United States Space Station Program are outlined. The power required to support Space Station missions and housekeeping loads is a key driver in overall Space Station design. conversely, Space Station requirements drive the power technology. Various power system technology options are discussed. The mission analysis studies resulting in the required Space Station capabilities are also discussed. An example of Space Station functions and a concept to provide them is presented. The weight, area, payload and altitude requirements on draft and mass requirements are described with a summary and status of key power systems technology requirements and issues.

Baraona, C. R.

1984-01-01

272

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

273

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

274

Access to space studies  

NASA Astrophysics Data System (ADS)

The National Aeronautics and Space Administration is currently considering possible directions in Earth-to-orbit vehicle development under a study called 'Access to Space.' This agency-wide study is considering commercial launch vehicles, human transportation, space station logistics, and other space transportation requirements over the next 40 years. Three options are being considered for human transportation: continued use of the Space Shuttle; development of a small personnel carrier (personnel logistics system (PLS)); or development of an advanced vehicle such as a single-stage-to-orbit (SSTO). Several studies related to the overall Access to Space study are reported in this document.

Martin, James A.

1993-11-01

275

Teichmller Spaces and the Bers embedding Bergman spaces and Bers spaces  

E-print Network

Teichmüller Spaces and the Bers embedding Bergman spaces and Bers spaces Application to Teichmüller spaces Asymptotic Teichmüller space Local rigidity of infinite dimensional Teichmüller Spaces A. Fletcher University, Newark, 2008 A. Fletcher Inf Dim Teich Spaces #12;Teichmüller Spaces and the Bers embedding

Fletcher, Alastair

276

Space mission support by NASA Space Network  

NASA Technical Reports Server (NTRS)

Normal NASA operational considerations and Phase 1 of Space Network (SN) interoperability foresees S band cross support between user spacecraft and space networks or partnering agencies. A typical interoperable scenario for an S band user spacecraft of a partner space agency with the NASA SN is presented. ESA's Hermes Manned Spaceplane exemplifies a typical interoperable user. In order to demonstrate the support potential of the NASA SN, the internal and external interfaces of the TDRSS (Tracking and Data Relay Satellite System), ATDRSS (Advanced TDRSS), and supporting elements are examined. Communications and operational requirements for a typical mission supported by the NASA SN are discussed.

Godfrey, Robert

1991-01-01

277

Architecting space communication networks  

E-print Network

Reliable communication and navigation services are critical to robotic and human space missions. NASA currently provides them through three independent and uncoordinated network that consist of both Earth-based and space-based ...

Sanchez Net, Marc

2014-01-01

278

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.

279

astronautics & space technology  

E-print Network

in areas such as electric propulsion, plasma physics, heliospheric structure, fundamental processes and chemistry, and will learn spacecraft and rocket design and operations, propulsion, orbital mechanics plasma physics, spacecraft in plasma, radiation effects on space systems, space instrumentation: de

Rohs, Remo

280

Characterizing Protein Conformation Space  

E-print Network

In this work, we propose a radical approach for exploring the space of all possible protein structures. We present techniques to explore the clash-free conformation space, which comprises all protein structures whose atoms ...

Nigham, Anshul

281

Pathfinder: Humans in space  

NASA Technical Reports Server (NTRS)

Viewgraphs are presented on the Pathfinder program. Information is given on human exploration of the solar system, technical requirements interfaces, program objectives, space suits, human performance, man-machine systems, space habitats, life support systems, and artificial gravity

Anderson, John L.

1988-01-01

282

Space spider crane  

NASA Technical Reports Server (NTRS)

A space spider crane for the movement, placement, and or assembly of various components on or in the vicinity of a space structure is described. As permanent space structures are utilized by the space program, a means will be required to transport cargo and perform various repair tasks. A space spider crane comprising a small central body with attached manipulators and legs fulfills this requirement. The manipulators may be equipped with constant pressure gripping end effectors or tools to accomplish various repair tasks. The legs are also equipped with constant pressure gripping end effectors to grip the space structure. Control of the space spider crane may be achieved either by computer software or a remotely situated human operator, who maintains visual contact via television cameras mounted on the space spider crane. One possible walking program consists of a parallel motion walking program whereby the small central body alternatively leans forward and backward relative to end effectors.

Macconochie, Ian O. (inventor); Mikulas, Martin M., Jr. (inventor); Pennington, Jack E. (inventor); Kinkead, Rebecca L. (inventor); Bryan, Charles F., Jr. (inventor)

1988-01-01

283

French space activities  

NASA Technical Reports Server (NTRS)

The four main points of research and development of space programs by France are explained. The National Center of Space Studies is discussed, listing the missions of the Center and describing the activities of the staff.

Blanc, R.

1982-01-01

284

Space Traveler Project.  

ERIC Educational Resources Information Center

Describes the winners of the Space Traveler Project, a contest jointly sponsored by Rockwell International, NASA, and this magazine to identify worthwhile elementary science programs relating to the Space Shuttle. (SJL)

Instructor, 1981

1981-01-01

285

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

286

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

287

Access to space: The Space Shuttle's evolving rolee  

Microsoft Academic Search

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

Steven R. Duttry

1993-01-01

288

SPACE SHUTTLE PROGRAM Space Shuttle Projects Office (MSFC)  

E-print Network

SPACE SHUTTLE PROGRAM Space Shuttle Projects Office (MSFC) NASA Marshall Space Flight Center SHUTTLE PROGRAM Space Shuttle Projects Office (MSFC) NASA Marshall Space Flight Center, Huntsville · No Significant Changes · Readiness Statement #12;SPACE SHUTTLE PROGRAM Space Shuttle Projects Office (MSFC) NASA

Christian, Eric

289

Deep Space Telecommunications  

NASA Technical Reports Server (NTRS)

The increasing load on NASA's deep Space Network, the new capabilities for deep space missions inherent in a next-generation radio telescope, and the potential of new telescope technology for reducing construction and operation costs suggest a natural marriage between radio astronomy and deep space telecommunications in developing advanced radio telescope concepts.

Kuiper, T. B. H.; Resch, G. M.

2000-01-01

290

Space Photography 1977 Index  

NASA Technical Reports Server (NTRS)

An index is provided to representative photographs and transparencies available from NASA. Subjects include spacecraft, astronauts, lunar surface, planets and outer space phenomena, earth observations, and aviation. High altitude aircraft infrared photographs are included along with artists' conceptions of space shuttle and space colonies.

1976-01-01

291

Space processing applications bibliography  

NASA Technical Reports Server (NTRS)

This special bibliography lists 724 articles, papers, and reports which discuss various aspects of the use of the space environment for materials science research or for commercial enterprise. The potentialities of space processing and the improved materials processes that are made possible by the unique aspects of the space environment are emphasized. References identified in April, 1978 are cited.

1978-01-01

292

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

293

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

294

Radiation effects in space  

SciTech Connect

As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

Fry, R.J.M.

1987-07-01

295

Isometries between leaf spaces  

E-print Network

In this paper we prove that an isometry between orbit spaces of two proper isometric actions is smooth if it preserves the codimension of the orbits or if the orbit spaces have no boundary. In other words, we generalize Myers-Steenrod's theorem for orbit spaces. These results are proved in the more general context of singular Riemannian foliations.

Alexandrino, Marcos M

2011-01-01

296

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

297

Marshall Space Flight Center  

NASA Astrophysics Data System (ADS)

NASA's George C Marshall Space Flight Center is located in Huntsville, Alabama. It is the agency's leading center for space transportation and propulsion development. The Saturn launch vehicles used in the Apollo Moon program were designed and developed here. Today, it provides the solid rocket boosters, main engines and external tank for the Space Shuttle. Apart from upgrades to these systems, M...

Murdin, P.

2000-11-01

298

Space travel and gravity  

Microsoft Academic Search

Space travelling is not possible for human because, by the time, we cross Jupiter, our bones dissolve as there is zero gravity and, by developing a gravity chamber in the space ship itself we will be able to travel in space for generations and explore the universe.

P. Karmakar; Greeninavin

2010-01-01

299

Autonomous space shuttle  

Microsoft Academic Search

The continued assembly and operation of the International Space Station (ISS) is the cornerstone within NASA's overall strategic plan. As indicated in NASA's Integrated Space Transportation Plan (ISTP), the International Space Station requires shuttle to fly through at least the middle of the next decade to complete assembly of the station, provide crew transport, and to provide heavy lift up

J. A. Siders; R. H. Smith

2004-01-01

300

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.

Idaho PTV

2011-09-21

301

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

302

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

303

Suited for Space  

NASA Technical Reports Server (NTRS)

This viewgraph presentation describes the basic functions of space suits for EVA astronauts. Space suits are also described from the past, present and future space missions. The contents include: 1) Why Do You Need A Space Suit?; 2) Generic EVA System Requirements; 3) Apollo Lunar Surface Cycling Certification; 4) EVA Operating Cycles for Mars Surface Missions; 5) Mars Surface EVA Mission Cycle Requirements; 6) Robustness Durability Requirements Comparison; 7) Carry-Weight Capabilities; 8) EVA System Challenges (Mars); 9) Human Planetary Surface Exploration Experience; 10) NASA Johnson Space Center Planetary Analog Activities; 11) Why Perform Remote Field Tests; and 12) Other Reasons Why We Perform Remote Field Tests.

Kosmo, Joseph J.

2006-01-01

304

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

305

Space science setbacks discussed  

NASA Astrophysics Data System (ADS)

Making the best of a difficult situation seemed to be the recurring theme of a forum on the future of U.S. space science held earlier this month at the meeting of the American Physical Society's Division of Plasma Physics in Baltimore, Md. The loss of the space shuttle Challenger has had “immediate and very substantial” effects on space science, according to Jeffrey D. Rosendhal of the Office of Space Science and Applications at the National Aeronautics and Space Administration (NASA), one of four speakers at the forum.

Katzoff, Judith A.

306

Swamp to Space exhibit  

NASA Technical Reports Server (NTRS)

The menacing-looking alligator is really harmless. It is one of the realistic props to help convince visitors that the feel of the swamp is real in StenniSphere's Swamp to Space exhibit at John C. Stennis Space Center in Hancock County, Miss. The historical section of the Swamp to Space exhibit tells the story of why and how Stennis Space Center came to be. It also pays tribute to the families who moved their homes to make way for the space age in Mississippi.

2000-01-01

307

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

308

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

309

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

310

Madrid space station  

NASA Technical Reports Server (NTRS)

The Madrid space station, operated under bilateral agreements between the governments of the United States and Spain, is described in both Spanish and English. The space station utilizes two tracking and data acquisition networks: the Deep Space Network (DSN) of the National Aeronautics and Space Administration and the Spaceflight Tracking and Data Network (STDN) operated under the direction of the Goddard Space Flight Center. The station, which is staffed by Spanish employees, comprises four facilities: Robledo 1, Cebreros, and Fresnedillas-Navalagamella, all with 26-meter-diameter antennas, and Robledo 2, with a 64-meter antenna.

Fahnestock, R. J.; Renzetti, N. A.

1975-01-01

311

Pioneer Anomaly and Accelerating Universe as Effects of the Minkowski Space Conformal Symmetry  

E-print Network

On the basis of the nonisometric transformations subgroup of the SO(4.2) group, the nonlinear time inhomogeneity one-parameter conformal transformations are constructed. The connection between the group parameter and the Hubble constant H0 is established. It is shown that the existence of an anomalous blue-shifted frequency drift is a pure kinematic manifestation of the time inhomogeneity induced by the Universe expansion. This conclusion is confirmed via a generalization of the standard Special Relativity clock synchronization procedure to the space expanding case. The obtained formulae are in accordance with the observable Pioneer Anomaly effect. The anomalous blue-shifted drift is universal, does not depend on the presence of graviting centers and can be, in principle, observed on any frequencies under suitable experimental conditions. The explicit analytic expression for the speed of recession--intergalactic distance ratio is obtained in the form of a function of the red shift z valid in the whole range of its variation. In the small z limit this expression exactly reproduces the Hubble law. The maximum value of this function at z=0.475 quantitatively corresponds to the experimentally found value z(exp) = 0.46 +/- 0.13 of the transition from the decelerated to the accelerated expansion of the Universe.

L. M. Tomilchik

2007-04-20

312

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

313

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

314

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

315

National Aeronautics and Space Administration Space Life and Physical Sciences  

E-print Network

National Aeronautics and Space Administration Space Life and Physical Sciences D National Laboratory management organization (CASIS) #12;National Aeronautics and Space Administration #12;National Aeronautics and Space Administration geneLAB Campaign Progress To move forward

Waliser, Duane E.

316

National Aeronautics and Space Administration Human Space Exploration  

E-print Network

National Aeronautics and Space Administration Human Space Exploration Framework Summary For Public Release 1 #12;Overview Context and approach for human space exploration Key guiding time. Human Space Exploration Architecture Planning Human spaceflight (HSF) programs

Waliser, Duane E.

317

National Aeronautics and Space Administration SPACE SHUTTLE MISSION  

E-print Network

National Aeronautics and Space Administration SPACE SHUTTLE MISSION STS-133 PRESS KIT/February 2011 .................................................. 51 SPACE SHUTTLE DETAILED TEST OBJECTIVES (DTO) AND DETAILED SUPPLEMENTARY OBJECTIVES (DSO).............................................................................................................................. 54 HISTORY OF SPACE SHUTTLE DISCOVERY

318

UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP  

E-print Network

UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP 18th September 2012 STFC 2012 #12;UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP 18th September 2012 STFC · Conclusion #12;UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP 18th September 2012 STFC

319

space for science, enterprise and environment Bringing Space Into School  

E-print Network

space for science, enterprise and environment Bringing Space Into School Science The National Space Education Initiative #12;space for science, enterprise and environment National Space Education Initiative the consultations · Recommendations of the report #12;space for science, enterprise and environment Background

320

Public choice economics and space policy: realising space tourism  

Microsoft Academic Search

Government space agencies have the statutory responsibility to suport the commercialisation of space activities. NASA's 1998 report “General Public Space Travel and Tourism” concluded that passenger space travel can start using already existing technology, and is likely to grow into the largest commercial activity in space: it is therefore greatly in taxpayers' economic interest that passenger space travel and accommodation

Patrick Collins

2001-01-01

321

Quantum-Space Attacks  

E-print Network

Theoretical quantum key distribution (QKD) protocols commonly rely on the use of qubits (quantum bits). In reality, however, due to practical limitations, the legitimate users are forced to employ a larger quantum (Hilbert) space, say a quhexit (quantum six-dimensional) space, or even a much larger quantum Hilbert space. Various specific attacks exploit of these limitations. Although security can still be proved in some very special cases, a general framework that considers such realistic QKD protocols, as well as} attacks on such protocols, is still missing. We describe a general method of attacking realistic QKD protocols, which we call the `quantum-space attack'. The description is based on assessing the enlarged quantum space actually used by a protocol, the `quantum space of the protocol'. We demonstrate these new methods by classifying various (known) recent attacks against several QKD schemes, and by analyzing a novel attack on interferometry-based QKD.

Ran Gelles; Tal Mor

2007-11-25

322

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

323

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

324

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

325

Intelligent spaces: An overview  

Microsoft Academic Search

This paper presents a brief review of state-of-the- art research in the field of intelligent spaces. With the increased availability of smart sensors and context-aware appliances that are equipped with embedded computing and communication capability, the intelligent space concept have found widespread applications. First, we introduce the concept, and applications of intelligent spaces. Then we explore research issues on the

Bin Liu; Fei-Yue Wang; Jason Geng; Qingming Yao; Hui Gao; Buqing Zhang

2007-01-01

326

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

327

Matter: Space without Time  

E-print Network

While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that the concept of matter as space without time provides a framework which unifies matter with spacetime and in which we anticipate the development of complete theories (ideally a single unified theory) describing observed 'particles, charges, fields and forces' solely with the geometry of our matter-space-time universe.

Yousef Ghazi-Tabatabai

2012-11-19

328

Space Systems Laboratory (SSL)  

NSDL National Science Digital Library

The Space Systems Laboratory (SSL) at the University of Maryland is investigating human and robotic performance in space. Among the many projects being conducted at the SSL are a telerobotic spacecraft servicer called Ranger--to be launched into Earth orbit via an expendable rocket in 1997, and a Space Shuttle flight experiment which will investigate human fatigue during extravehicular activities (spacewalks). The SSL Home Page presents the projects, personnel, and facilities of the lab.

329

A Week for Space  

NSDL National Science Digital Library

Space Week focuses on concepts that enable students to make concrete observations in the early grades (K--2) and move to concepts that help students develop their internet research and writing skills in middle and upper grades (Grades 3--5), and culminates with the development of science investigation design skills (Grade 6). To help launch your students' interest in space science, this article presents inquiry-based space lessons, which are aligned with the National Science Education Standards.

Comstock, Diane

2008-09-01

330

Space technology research plans  

NASA Technical Reports Server (NTRS)

Development of new technologies is the primary purpose of the Office of Aeronautics and Space Technology (OAST). OAST's mission includes the following two goals: (1) to conduct research to provide fundamental understanding, develop advanced technology and promote technology transfer to assure U.S. preeminence in aeronautics and to enhance and/or enable future civil space missions: and (2) to provide unique facilities and technical expertise to support national aerospace needs. OAST includes both NASA Headquarters operations as well as programmatic and institutional management of the Ames Research Center, the Langley Research Center and the Lewis Research Center. In addition. a considerable portion of OAST's Space R&T Program is conducted through the flight and science program field centers of NASA. Within OAST, the Space Technology Directorate is responsible for the planning and implementation of the NASA Space Research and Technology Program. The Space Technology Directorate's mission is 'to assure that OAST shall provide technology for future civil space missions and provide a base of research and technology capabilities to serve all national space goals.' Accomplishing this mission entails the following objectives: y Identify, develop, validate and transfer technology to: (1) increase mission safety and reliability; (2) reduce flight program development and operations costs; (3) enhance mission performance; and (4) enable new missions. Provide the capability to: (1) advance technology in critical disciplines; and (2) respond to unanticipated mission needs. In-space experiments are an integral part of OAST's program and provides for experimental studies, development and support for in-space flight research and validation of advanced space technologies. Conducting technology experiments in space is a valuable and cost effective way to introduce advanced technologies into flight programs. These flight experiments support both the R&T base and the focussed programs within OAST.

Hook, W. Ray

1992-01-01

331

Nuclear power in space  

NASA Astrophysics Data System (ADS)

Written and verbal testimony presented before the House Subcommittee on Energy Research and Development is documented. Current research efforts related to space nuclear power are discussed including the SP-100 Space Reactor Program, development of radioisotope thermoelectric generators, and the Advanced Nuclear Systems Program. Funding, research and test facilities, specific space mission requirements, and the comparison of solar and nuclear power systems are addressed. Witnesses included representatives from DOD, NASA, DOE, universities, and private industry.

332

Aging and space travel  

NASA Technical Reports Server (NTRS)

The matter of aging and its relation to space vehicle crewmembers undertaking prolonged space missions is addressed. The capabilities of the older space traveler to recover from bone demineralization and muscle atrophy are discussed. Certain advantages of the older person are noted, for example, a greater tolerance of monotony and repetitious activities. Additional parameters are delineated including the cardiovascular system, the reproductive system, ionizing radiation, performance, and group dynamics.

Mohler, S. R.

1982-01-01

333

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

334

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

335

Nuclear power in space  

SciTech Connect

Nuclear reactors have provided energy for satellites-with nearly disastrous results. Now the US government is proposing to build nuclear-powered boosters to launch Star Wars defenses. These authors represent scientific groups that are opposed to the use of nuclear power in near space. The authors feel that the best course for space-borne reactors is to ban them from Earth orbit and use them in deep space.

Aftergood, S. (Federation of American Scientists, Washington, DC (USA)); Hafemeister, D.W. (California Polytechnic State Univ., Pomona (USA)); Prilutsky, O.F.; Rodionov, S.N. (Space Research Inst., Moscow (USSR)); Primack, J.R. (Univ. of California, Santa Cruz (USA))

1991-06-01

336

Space applications of superconductivity  

NASA Technical Reports Server (NTRS)

Some potential applications of superconductivity in space are summarized, e.g., the use of high field magnets for cosmic ray analysis or energy storage and generation, space applications of digital superconducting devices, such as the Josephson switch and, in the future, a superconducting computer. Other superconducting instrumentation which could be used in space includes: low frequency superconducting sensors, microwave and infrared detectors, instruments for gravitational studies, and high-Q cavities for use as stabilizing elements in clocks and oscillators.

Sullivan, D. B.; Vorreiter, J. W.

1979-01-01

337

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.

338

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

339

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

340

Space Transportation Propulsion Systems  

NASA Technical Reports Server (NTRS)

This report outlines the Space Transportation Propulsion Systems for the NPSS (Numerical Propulsion System Simulation) program. Topics include: 1) a review of Engine/Inlet Coupling Work; 2) Background/Organization of Space Transportation Initiative; 3) Synergy between High Performance Computing and Communications Program (HPCCP) and Advanced Space Transportation Program (ASTP); 4) Status of Space Transportation Effort, including planned deliverables for FY01-FY06, FY00 accomplishments (HPCCP Funded) and FY01 Major Milestones (HPCCP and ASTP); and 5) a review current technical efforts, including a review of the Rocket-Based Combined-Cycle (RBCC), Scope of Work, RBCC Concept Aerodynamic Analysis and RBCC Concept Multidisciplinary Analysis.

Liou, Meng-Sing; Stewart, Mark E.; Suresh, Ambady; Owen, A. Karl

2001-01-01

341

AB Space Engine  

E-print Network

On 4 January 2007 the author published the article Wireless Transfer of Electricity in Outer Space in http://arxiv.org wherein he offered and researched a new revolutionary method of transferring electric energy in space. In that same article, he offered a new engine which produces a large thrust without throwing away large amounts of reaction mass (unlike the conventional rocket engine). In the current article, the author develops the theory of this kind of impulse engine and computes a sample project which shows the big possibilities opened by this new AB-Space Engine. The AB-Space Engine gets the energy from ground-mounted power; a planet electric station can transfer electricity up to 1000 millions (and more) of kilometers by plasma wires. Author shows that AB-Space Engine can produce thrust of 10 tons (and more). That can accelerate a space ship to some thousands of kilometers/second. AB-Space Engine has a staggering specific impulse owing to the very small mass expended. The AB-Space Engine reacts not by expulsion of its own mass (unlike rocket engine) but against the mass of its planet of origin (located perhaps a thousand of millions of kilometers away) through the magnetic field of its plasma cable. For creating this plasma cable the AB-Space Engine spends only some kg of hydrogen.

Alexander Bolonkin

2008-03-02

342

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

343

Man in space  

NASA Astrophysics Data System (ADS)

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 carring out various EVA's were developed. In the course of the Salyut-7 space station orbital operation the EVA's have become regular. The authour of the report as the participant of the EVA's considers the main steps of man activities in space and analizes specific problems arized in performing such activities.

Solovjev, V. A.

1987-09-01

344

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.

345

Beyond Space-Time  

E-print Network

These notes, based on the remarks made at the 23 Solvay Conference, collect several speculative ideas concerning gauge/ strings duality, de Sitter spaces, dimensionality and the cosmological constant.

A. M. Polyakov

2006-02-01

346

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

347

Space nuclear power systems  

NASA Technical Reports Server (NTRS)

Space nuclear power systems are considered for use in those particular spacecraft applications for which nuclear power systems offer unique advantages over solar and/or chemical space power systems. Both isotopic and reactor heated space electrical power units are described in an attempt to illustrate their operating characteristics, spacecraft integration aspects, and factory-to-end of mission operational considerations. The status of technology developments in nuclear power systems is presented. Some projections of those technologies are made to form a basis for the applications of space nuclear power systems to be expected over the next 10-15 years.

Carpenter, R. T.

1972-01-01

348

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

349

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.

350

Microtechnology in space bioreactors.  

PubMed

Space biology is a young and rapidly developing discipline comprising basic research and biotechnology. In the next decades it will play a prominent role in the International Space Station (ISS). Therefore, there is an increasing demand for sophisticated instrumentation to satisfy the requirements of the future projects in space biology. Bioreactors will be needed to supply fresh living material (cells and tissues) either to study still obscure basic biological mechanisms or to develop profitable bioprocesses which will take advantage of the peculiar microgravity conditions. Since more than twenty years, the Space Biology Group of the ETHZ is carrying out research projects in space (Space Shuttle/Spacelab, MIR Station, satellites, and sounding rockets) that involve also the development of space-qualified instrumentation. In the last ten years we have developed, in collaboration with Mecanex SA, Nyon, and the Institute of Microtechnology of the University of Neuchatel, a space bioreactor for the continuous culture of yeast cells under controlled conditions. Sensors, pH control, nutrients pump and fluid flowmeter are based on state-of-the-art silicon technology. After two successful space flights, a further improved version is presently prepared for a flight in the year 2000. PMID:11542392

Walther, I; van der Schoot, B; Boillat, M; Muller, O; Cogoli, A

1999-03-01

351

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

352

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

353

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

354

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

355

Multimegawatt space power reactors  

SciTech Connect

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. 31 figs.

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

1989-01-01

356

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

357

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.

358

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

359

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

360

National Aeronautics and Space Administration  

E-print Network

: Ares I and Ares V Living and Working in Space Supporting Life in Space International Space Station and scientific discovery. NASA will use the space shuttle to complete the International Space Station, before. The space station, which is scheduled to be completed by 2010, is a laboratory where we are learning how

Christian, Eric

361

Recent results from the Hubble Space Telescope  

NASA Astrophysics Data System (ADS)

The present survey of observational results from the HST supplements the earlier presentation by Kinney and Maran (1991), and encompasses such noteworthy achievements as the first UV results from the High Speed Photometer and spectroscopic studies of black hole/neutron-star binaries and a flare star. New data are also presented for the intergalactic absorption clouds along various lines-of-sight and imaging observations of planetary nebulae in the Magellanic Clouds. An animated sequence derived from images showing the evolution of a great storm on Saturn is noted to be of especially far-ranging relevance.

Maran, Stephen P.; Kinney, Anne L.

1993-05-01

362

Recent results from the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

The present survey of observational results from the HST supplements the earlier presentation by Kinney and Maran (1991), and encompasses such noteworthy achievements as the first UV results from the High Speed Photometer and spectroscopic studies of black hole/neutron-star binaries and a flare star. New data are also presented for the intergalactic absorption clouds along various lines-of-sight and imaging observations of planetary nebulae in the Magellanic Clouds. An animated sequence derived from images showing the evolution of a great storm on Saturn is noted to be of especially far-ranging relevance.

Maran, Stephen P.; Kinney, Anne L.

1993-01-01

363

Physiologic adaptation to space - Space adaptation syndrome  

NASA Technical Reports Server (NTRS)

The adaptive changes of the neurovestibular system to microgravity, which result in space motion sickness (SMS), are studied. A list of symptoms, which range from vomiting to drowsiness, is provided. The two patterns of symptom development, rapid and gradual, and the duration of the symptoms are described. The concept of sensory conflict and rearrangements to explain SMS is being investigated.

Vanderploeg, J. M.

1985-01-01

364

Galactic Winds in the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

We have performed hydrodynamical simulations to investigate the effects of galactic winds on the high-redshift (z=3) universe. Strong winds suppress the formation of low-mass galaxies significantly, and the metals carried by them produce C IV absorption lines with properties in reasonable agreement with observations. The winds have little effect on the statistics of the H I absorption lines, because the hot gas bubbles blown by the winds fill only a small fraction of the volume and because they tend to escape into the voids, thereby leaving the filaments that produce these lines intact. Based on observations made at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology and the University of California; it was made possible by the generous support of the W. M. Keck Foundation.

Theuns, Tom; Viel, Matteo; Kay, Scott; Schaye, Joop; Carswell, Robert F.; Tzanavaris, Panayiotis

2002-10-01

365

Chinese Space Program  

NSDL National Science Digital Library

China will soon make history by sending the first Chinese man to space. Scheduled for sometime in 2003, it will be the first step toward China's highly ambitious plans for space exploration.The China National Space Administration Web site (1) has a detailed description of the country's space policy. Aerospace China, a journal published online by the administration, has information on space development plans and other issues. The history of China's space program is recounted by the online Encyclopedia Astronautica (2). Several influential scientists and their contributions to Chinese rocketry and satellite technology are highlighted. The China Academy of Launch Vehicle Technology (3) sent the first Chinese satellite into space. Its home page showcases eight launch vehicles and offers an extensive technical description of the LM-3C model. The work of various research groups at the Shanghai Astronomical Observatory (4) deals with topics ranging from satellite dynamics to stellar astronomy. Some of the groups have details of their projects and facilities online. Another observatory studies molecular clouds and star formation (5). A large collection of its research papers are provided on its Web site. A news article from Space.com (6) discusses the forthcoming launch of the Shenzhou IV spacecraft, scheduled for later this year. It is generating considerable interest, since it is said to be identical to China's first manned spacecraft, expected to launch in 2003. Another article (7) considers China's rapidly developing space program. With the tremendous effort and lofty goals for moon bases and Mars missions, the author argues that China could eventually rival the US. Many more news stories about the Chinese space program can be found on the Dragon Space Web site (8).

Leske, Cavin.

2002-01-01

366

Cognitive neuroscience in space.  

PubMed

Humans are the most adaptable species on this planet, able to live in vastly different environments on Earth. Space represents the ultimate frontier and a true challenge to human adaptive capabilities. As a group, astronauts and cosmonauts are selected for their ability to work in the highly perilous environment of space, giving their best. Terrestrial research has shown that human cognitive and perceptual motor performances deteriorate under stress. We would expect to observe these effects in space, which currently represents an exceptionally stressful environment for humans. Understanding the neurocognitive and neuropsychological parameters influencing space flight is of high relevance to neuroscientists, as well as psychologists. Many of the environmental characteristics specific to space missions, some of which are also present in space flight simulations, may affect neurocognitive performance. Previous work in space has shown that various psychomotor functions degrade during space flight, including central postural functions, the speed and accuracy of aimed movements, internal timekeeping, attentional processes, sensing of limb position and the central management of concurrent tasks. Other factors that might affect neurocognitive performance in space are illness, injury, toxic exposure, decompression accidents, medication side effects and excessive exposure to radiation. Different tools have been developed to assess and counteract these deficits and problems, including computerized tests and physical exercise devices. It is yet unknown how the brain will adapt to long-term space travel to the asteroids, Mars and beyond. This work represents a comprehensive review of the current knowledge and future challenges of cognitive neuroscience in space from simulations and analog missions to low Earth orbit and beyond. PMID:25370373

De la Torre, Gabriel G

2014-01-01

367

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

368

Space technology research plans  

Microsoft Academic Search

Development of new technologies is the primary purpose of the Office of Aeronautics and Space Technology (OAST). OAST's mission includes the following two goals: (1) to conduct research to provide fundamental understanding, develop advanced technology and promote technology transfer to assure U.S. preeminence in aeronautics and to enhance and\\/or enable future civil space missions: and (2) to provide unique facilities

W. Ray Hook

1992-01-01

369

What Is Space Weather?  

NSDL National Science Digital Library

This resource provides a brief overview of the phenomenon known as space weather, which happens when energetic particles emitted by the Sun impact the Earth's magnetosphere. Users can view images, video clips, and animations of auroras and other types of space weather. A set of links to related websites is also provided.

370

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

371

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.

372

Language, Gesture, and Space.  

ERIC Educational Resources Information Center

A collection of papers addresses a variety of issues regarding the nature and structure of sign language, gesture, and gesture systems. Articles include: "Theoretical Issues Relating Language, Gesture, and Space: An Overview" (Karen Emmorey, Judy S. Reilly); "Real, Surrogate, and Token Space: Grammatical Consequences in ASL American Sign Language"…

Emmorey, Karen, Ed.; Reilly, Judy S., Ed.

373

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

374

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

375

Reframing Children's Spaces  

ERIC Educational Resources Information Center

Like professional photographers, early childhood teachers can reframe their perspectives to create innovative and inspiring spaces for young children by concentrating on reframing two design elements: color and texture. When thinking about designing spaces for young children, one of the first considerations is the equipment and its arrangement.…

Duncan, Sandra

2011-01-01

376

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

377

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

378

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

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

How to Manage Space.  

ERIC Educational Resources Information Center

Major institutions and organizations are increasingly recognizing the need for organized and structured action on space administration. In large organizations the successful administration of space matters requires a committee that includes an architect; an engineer; and ranking persons from personnel, planning, and finance departments. Procedures…

Cavanaugh, R. B.

381

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.

382

Hazard Alert: Confined Spaces  

MedlinePLUS

... NIOSH. www.cpwr.com What is a confined space? Ask questions It is the employer’s responsibility to ... union. Call OSHA 1-800-321-OSHA COnFIned SpACeS Get training Your employer must train you for ...

383

Space Telescope pointing control  

Microsoft Academic Search

The Space Telescope, a long life, high performance spacecraft deployed by the Space Shuttle, will carry five scientific instruments on its first mission. Its pointing control system will permit target-to-target maneuvering and precision pointing on a target star to support scientific objectives. Spacecraft attitude control is achieved by onboard computer processing of attitude and rate sensor data to generate reaction

H. Dougherty; C. Rodoni; J. Rodden; K. Tompetrini

1984-01-01

384

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

385

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

386

The Space Station  

Microsoft Academic Search

The configuration of the Space Station under design studies by NASA is limited only by the capabilities of the Shuttle and the purposes to which it is applied. Once the standard interlocks, launch vibration modes, and pallet designs are fixed, all other assembly of modular components, testing, and trim will be performed in space. The Station will serve for long-term

R. Sharples; J. Hieatt

1984-01-01

387

The Space Station era  

Microsoft Academic Search

The users, configuration, and uses of the manned Space Station planned by the U.S. are outlined. The station is to be operational by 1994 and will serve scientific and commercial purposes. It is noted that the exploration of space, like the exploration of any other newly discovered, remote territory, requires the establishment of a base camp. Invitations have been extended

J. M. Beggs

1984-01-01

388

Meeting Library Space Needs.  

ERIC Educational Resources Information Center

The physical arrangement of reading, storage, and service areas for the microform department of the Joseph Regenstein Library can serve as a case study for the estimation of space requirements for microform storage and retrieval. The library uses mechanical readers at carrel stations, each utilizing 31.5 square feet of floor space. The best…

Youngren, Ralph P.

389

Arrays for space applications  

NASA Technical Reports Server (NTRS)

Concepts that were studied for application in space based radar (SBR) systems are presented. These antenna systems were for low earth orbit and require large fields of view (FOV). The systems included both space-fed and corporate-fed arrays.

Schuman, Harvey K.; Antonik, Paul; Malagisi, Carmen

1989-01-01

390

Modeling the space shuttle  

Microsoft Academic Search

We summarize our methodology for modeling space shuttle processing using discrete event simulation. Why the project was initiated, what the overall goals were, how it was funded, and who were the members of the project team are identified. We describe the flow of the space shuttle flight hardware through the supporting infrastructure and how the-model was created to accurately portray

Grant R. Cates; Martin J. Steele; M. Mollaghasemi; G. Rabadi

2002-01-01

391

Latest Space Shuttle News  

NSDL National Science Digital Library

This site from NASA offers the latest news on the space shuttle program. It features a variety of articles on the program. Links to other sites on the shuttle program provide provide resources such as posters, educational materials and interactive resources. Users can use the site to learn more about the most recent space shuttle missions or any of the past missions.

2002-01-01

392

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

393

Hazard Alert: Confined Spaces  

MedlinePLUS

... on your worksite. Do not enter without proper training. Never enter alone. A self-employed handyman died in this water service manhole. He had been called to fix a water leak in an adjacent rental house and was working alone. Know the basics… ... SpACeS Get training Your employer must train you for confined space ...

394

Ad Hoc Information Spaces  

Microsoft Academic Search

We describe the concept of ad hoc information spaces as a way of distributing information in an environment depending on user mobility and relative location. Ad hoc information spaces are realised using a decentralised approach to ubiquitous computing, which is based on functionally self- contained devices and ad hoc networking. Users are able to construct and manipulate the properties of

Johan Redström; Lars Erik Holmquist; Per Dahlberg; Peter Ljungstrand

395

Print advertising: White space  

Microsoft Academic Search

A survey of North American ad agency creative directors (n=31) reveals that they use the “white space” executional format in print ads mainly to advertise new brands of products rather than services. Their not necessarily mutually exclusive reasons for designing a predominantly white-space ad are (1) artistic – the ad “looks good,” (2) to increase attention to the ad overall,

G. Douglas Olsen; John W. Pracejus; Thomas C. O'Guinn

2012-01-01

396

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?

2002-01-22

397

Hyperrelations in version space  

Microsoft Academic Search

A version space is a set of all hypotheses consistent with a given set of training examples, delimited by the specific boundary and the general boundary. In existing studies [4, 5, 3] a hypothesis is a conjunction of attribute-value pairs, which is shown to have limited expressive power [6].In this paper we investigate version space in a more expressive hypothesis

Hui Wang; Ivo Düntsch; Günther Gediga; Andrzej Skowron

2002-01-01

398

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

Code of Federal Regulations, 2010 CFR

...toilet spaces; and shower spaces. (a) For the purposes...washing, or shower space that is accessible...toilet, washing or shower space that is accessible...person occupancy sleeping spaces; and (3) “Public...washing, or shower space that is not private...

2010-10-01

399

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

Code of Federal Regulations, 2013 CFR

...toilet spaces; and shower spaces. (a) For the purposes...washing, or shower space that is accessible...toilet, washing or shower space that is accessible...person occupancy sleeping spaces; and (3) “Public...washing, or shower space that is not private...

2013-10-01

400

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

Code of Federal Regulations, 2014 CFR

...toilet spaces; and shower spaces. (a) For the purposes...washing, or shower space that is accessible...toilet, washing or shower space that is accessible...person occupancy sleeping spaces; and (3) “Public...washing, or shower space that is not private...

2014-10-01

401

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

Code of Federal Regulations, 2012 CFR

...toilet spaces; and shower spaces. (a) For the purposes...washing, or shower space that is accessible...toilet, washing or shower space that is accessible...person occupancy sleeping spaces; and (3) “Public...washing, or shower space that is not private...

2012-10-01

402

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

Code of Federal Regulations, 2011 CFR

...toilet spaces; and shower spaces. (a) For the purposes...washing, or shower space that is accessible...toilet, washing or shower space that is accessible...person occupancy sleeping spaces; and (3) “Public...washing, or shower space that is not private...

2011-10-01

403

National Aeronautics and Space Administration International Space StationInternational Space Station  

E-print Network

National Aeronautics and Space Administration International Space StationInternational Space;International Space Station FactsInternational Space Station Facts Spacecraft Mass: 799,046 lb (362,441 kg;Assembly Complete ConfigurationAssembly Complete Configuration International Space Station External Payload

Christian, Eric

404

Space and Antispace  

NASA Astrophysics Data System (ADS)

Physics at the fundamental level can be effectively reduced to an explanation of the structures and interactions of fermions. Fermions appear to be singularities rather than extended objects, but there is no obvious way of creating such structures within the 3-dimensional space of observation. However, the algebra associated with the Dirac equation appears to suggest that the fermion requires a double, rather than a single, vector space, and this would seem to be confirmed by the double rotation required by spin 1/2 objects, and the associated effects of zitterberwegung and Berry phase shift. Further investigation of the second `space' reveals that it is, in effect, an `antispace', which contains the same information as real space but in a less accessible form. The two spaces effectively cancel to produce a norm 0 (nilpotent) object which has exactly the mathematical structure required to be a fermionic singularity.

Rowlands, Peter

2013-09-01

405

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

406

Radiation Effects In Space  

SciTech Connect

Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

Tripathi, Ram K. [NASA Langley Research Center, MS - 188 E, Hampton VA 23681 (United States)

2011-06-01

407

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

408

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

409

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.

410

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

411

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

412

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

413

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

414

Space-QUEST: Experiments with quantum entanglement in space  

E-print Network

The European Space Agency (ESA) has supported a range of studies in the field of quantum physics and quantum information science in space for several years, and consequently we have submitted the mission proposal Space-QUEST (Quantum Entanglement for Space Experiments) to the European Life and Physical Sciences in Space Program. We propose to perform space-to-ground quantum communication tests from the International Space Station (ISS). We present the proposed experiments in space as well as the design of a space based quantum communication payload.

Rupert Ursin; Thomas Jennewein; Johannes Kofler; Josep M. Perdigues; Luigi Cacciapuoti; Clovis J. de Matos; Markus Aspelmeyer; Alejandra Valencia; Thomas Scheidl; Alessandro Fedrizzi; Antonio Acin; Cesare Barbieri; Giuseppe Bianco; Caslav Brukner; Jose Capmany; Sergio Cova; Dirk Giggenbach; Walter Leeb; Robert H. Hadfield; Raymond Laflamme; Norbert Lutkenhaus; Gerard Milburn; Momtchil Peev; Timothy Ralph; John Rarity; Renato Renner; Etienne Samain; Nikolaos Solomos; Wolfgang Tittel; Juan P. Torres; Morio Toyoshima; Arturo Ortigosa-Blanch; Valerio Pruneri; Paolo Villoresi; Ian Walmsley; Gregor Weihs; Harald Weinfurter; Marek Zukowski; Anton Zeilinger

2008-06-05

415

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

416

National Aeronautics and Space Administration NASAGoddardSpaceFlightCenter  

E-print Network

National Aeronautics and Space Administration NASAGoddardSpaceFlightCenter http Space Flight Center's IPP Office #12;National Aeronautics and Space Administration NASAGoddard/category ­ Processing requests for software release · Benefits of Reporting · Summary #12;National Aeronautics and Space

Christian, Eric

417

National Aeronautics and Space Administration Space Life and Physical Sciences  

E-print Network

National Aeronautics and Space Administration Space Life and Physical Sciences Status Briefing PRESIDENT'S BUDGET REQUEST SUMMARY National Aeronautics and Space Administration 6 #12;2014 Space Operations Budget National Aeronautics and Space Administration FY 2014 PRESIDENT'S BUDGET REQUEST SUMMARY 7 #12

Waliser, Duane E.

418

Spinorial space-time and privileged space direction (I)  

E-print Network

Spinorial space-time and privileged space direction (I) Luis Gonzalez-Mestres Abstract Contrary of a privileged space direction are not strange phenomena from the point of view of fundamental space-time geometry. As already emphasized in our previous papers on the subject, the spinorial space-time we

Paris-Sud XI, Université de

419

3742SPACE ISSUES AND RESOLUTION PROCEDURE Space issue or  

E-print Network

Page 1 3742SPACE ISSUES AND RESOLUTION PROCEDURE Space issue or conflict identified Do any of the strategies mitigate issue/conflict Complete Conflict Resolution Form Submit form to Space Management Office Space Management Office conduct issue/conflict analysis Space Management Office document possible

420

Overview of Space Business Space & Integrated Defense Systems  

E-print Network

Overview of Space Business Space & Integrated Defense Systems Mitsubishi Corporation August 26 in Rio de Janeiro and Belo Horizonte #12;MC's Space Business Involved with aerospace business more than 40 years, covering civil/commercial space business, defense related space business and defense

421

Space Robotic Capabilities David Kortenkamp (NASA Johnson Space Center)  

E-print Network

Johnson Space Center Space Robotic Capabilities David Kortenkamp (NASA Johnson Space Center) Liam) David Wettergreen (Carnegie Mellon University) Dan Clancy (NASA Ames) #12;Johnson Space Center 12/18/2001 Space Robotics State-of-Art 2 ! Motivation Science Objectives Mission Concepts Robots Human

Kortenkamp, David

422

NASA Johnson Space Center Leading Human Space Exploration  

E-print Network

NASA Johnson Space Center Leading Human Space Exploration NASA Advisory Council Commercial Space live Goal 3 Create innovative new space technologies for our exploration, science, and economic future & Mission Vision ­ Declaration of our future: JSC leads a global enterprise in human space exploration

Waliser, Duane E.

423

National Aeronautics and Space Administration Space Shuttle Era Facts  

E-print Network

boosters (SRBs), giant external fuel tank (ET) and three space shuttle main engines (SSMEs). It also putNational Aeronautics and Space Administration NASAfacts Space Shuttle Era Facts NASA's shuttle Shuttle Program's 30 years of missions. The space shuttle, officially called the Space Transportation

424

Space Travel Space Travel: Past, Present and Future  

E-print Network

Space Travel #12;Space Travel: Past, Present and Future The space age is a little over 50 years old October 1957 #12;Space Travel: Past, Present and Future About 500 people have been in orbit. A dozen have set foot on the Moon and it is 40 years since we have been there. Space travel is very exciting

Shirley, Yancy

425

National Aeronautics and Space Administration Space Shuttle Era Facts  

E-print Network

National Aeronautics and Space Administration NASAfacts Space Shuttle Era Facts NASA's shuttle Shuttle Program's 30 years of missions. The space shuttle, officially called the Space Transportation vehicle (OV), its twin solid rocket boosters (SRBs), giant external fuel tank (ET) and three space shuttle

426

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.

427

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

428

Space Weather Now  

NSDL National Science Digital Library

The NOAA Space Weather Now website provides non-technical information and an assortment of images detailing current space weather. Visitors can find summaries describing auroras, plots of current auroral ovals on the poles, and viewing information for the Northern and Southern Hemispheres. The Real-Time Solar Wind Pages furnish dynamic plots of data, geomagnetic activity test product information, and resources about the four instruments used to collect data on geomagnetic storms. The website features Space Weather Scales to help the public understand the severity of environmental disturbances due to geomagnetic storms, solar radiation storms, and radio blackouts. Visitors can find the latest news, alerts, advisory bulletins, and much more.

429

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

430

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.

431

SPACE TECHNOLOGY Actual Estimate  

E-print Network

SPACE TECHNOLOGY TECH-1 Actual Estimate Budget Authority (in $ millions) FY 2011 FY 2012 FY 2013 FY.6 29.5 29.5 29.5 29.5 29.5 29.5 Crosscutting Space Tech Development 120.4 187.7 293.8 272.1 266.6 259.7 247.0 Exploration Technology Development 144.6 189.9 202.0 215.5 215.7 214.5 216.5 Notional SPACE

432

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

433

Space Update CD  

NSDL National Science Digital Library

This is an interactive, real-time display system of space science images and data designed for museums and schools. The program displays hundreds of images and movies from space science research, all documented, with web references of how to find out more information. The materials also include a large number of space science educational activities. The software is available for purchase. Full-screen versions without support files are available for download but require a registration number after a 30-day demo period.

434

Views from Space  

NASA Astrophysics Data System (ADS)

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 earth have been able to participate as vicarious explorers through the records, and experiences and the photographs that have been returned. At the beginning of the space program hardly anyone thought of photographs from space as anything more than a branch of industrial photography. There were pictures of the spaceships, and launches and of astronauts in training, but these were all pictures taken on the ground. When John Glenn became America's first man in orbit, bringing a camera was an afterthought. An Ansco Autoset was purchased in a drug store and hastily modified so the astronaut could use it more easily while in his pressure suit. In 1962, everything that Glenn did was deemed an experiment. At the beginning of the program, no one knew for certain whether weightlessness would prevent a man from seeing, or from breathing, or from eating and swallowing. Photography was deemed nothing more than a recreational extra. Not only was little expected of those first pictures taken from space, but there was serious concern that taking pictures of other nations from orbit would be seen as an act of ill will and even one of war- as sovereign sensitive nations would resent having pictures taken by Americans orbiting overhead. A few years earlier, in 1957, in reaction to the Soviet launch of the first Sputnik satellite, scientists told congressman of the necessity of orbiting our own robot spacecraft-they predicted that one day we would take daily pictures of the world's weather. Congressman were incredulous. But space photography developed quickly. For security purposes, spy satellites took over many of the responsibilities we had depended upon aircraft like the high-flying U-2 spy planes for. Weather satellites permitted weather predictions as never before. Satellites were developed in the first ten years of the space program for earth resources and mapping. In this paper and presentation we will observe some of the best views taken in space and from space...of the Earth, and the moon and beyond. We will travel in space with our astronauts. Some of the photographs we will see are famous and others not nearly so. We will discuss some of the history behind the pictures and some of the benefits that have been gained from the views from space.

Kitmacher, Gary H.

2002-01-01

435

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

436

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

437

How Space Shuttles Work  

NSDL National Science Digital Library

This site explains the complexity of the entire mission of a space shuttle launch, orbit, activities, and return to Earth. Students and teachers can learn about the precise nature of space science including extensive preparations and examine the monumental technology behind Americas shuttle program, as well as the extraordinarily difficult mission it was designed to carry out. Information is also provided on the background and history of the space shuttle. Diagrams, full-color photos, highlighted terms and supplementary definitions assist users in understanding scientific terminology used to describe the extraordinary missions of shuttle astronauts, crew and specialists. A printable version of this information is also available on site.

Craig Freudenrich, Ph.D.

2008-01-01

438

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

439

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

440

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

441

Toward a History Space Shuttle  

E-print Network

Shuttle in building and servicing the Hubble Space Telescope and the International Space Station; science CHAPTER 7--THE SPACE SHUTTLE AND THE HUBBLE SPACE TELESCOPE ............. 34 CHAPTER 8--SCIENCEToward a History of the Space Shuttle An Annotated Bibliography Part 2, 1992­2011 Monographs

442

National Aeronautics and Space Administration  

E-print Network

. Transitioning from the Space Shuttle vehicle to the next-generation CEV was added as a most serious challenge accident in 2003. · Completing the International Space Station. · Transitioning from the Space Shuttle for Space Exploration by transitioning from the Space Shuttle Program to the CEV and other vehicles

Christian, Eric

443

International Space Exploration Coordination Group  

E-print Network

for collaborative space exploration missions beginning with the International Space Station (ISS) and continuingInternational Space Exploration Coordination Group The Global Exploration Roadmap August 2013 #12 The Global Exploration Roadmap is being developed by space agencies participating in the International Space

Rathbun, Julie A.

444

National Aeronautics and Space Administration Marshall Space Flight Center  

E-print Network

. Advanced propulsion and power research and development including high-power electric propulsion, nuclear thermal propulsion, space nuclear power systems, nuclear surface power systems, and propellant and Services marshall Propulsion Systems Space Transportation/ Launch Vehicles Space Systems Scientific

445

National Aeronautics and Space Administration Marshall Space Flight Center  

E-print Network

. Advanced propulsion and power research and development including high-power electric propulsion, nuclear thermal propulsion, space nuclear power systems, nuclear surface power systems, and propellant Propulsion Systems Space Transportation/ Launch Vehicles Space Systems Scientific Research Launching

Waliser, Duane E.

446

Spaces of idempotent measures of compact metric spaces  

Microsoft Academic Search

We investigate certain geometric properties of the spaces of idempotent measures. In particular, we prove that the space of idempotent measures on an infinite compact metric space is homeomorphic to the Hilbert cube.

Lidia Bazylevych; Dušan Repovš; Michael Zarichnyi

2010-01-01

447

Strange Stuff in Space  

NSDL National Science Digital Library

This section of the Windows to the Universe web site provides information and images about strange stuff in space including detailed information about supernovas, white dwarfs, neutron stars, black holes, quasars, gravitational lensing, and gamma ray bursters. Windows to the Universe is a user-friendly learning system pertaining to the Earth and Space sciences. The objective of this project is to develop an innovative and engaging web site that spans the Earth and Space sciences and includes a rich array of documents, including images, movies, animations, and data sets that explore the Earth and Space sciences and the historical and cultural ties between science, exploration and the human experience. Links at the top of each page allow users to navigate between beginner, intermediate and advanced levels.

Roberta Johnson

2000-07-01

448

Space: the final frontier.  

PubMed

Few things are misunderstood more by biotech startup management teams than the importance of creating working space conductive to innovation and productivity, and compatible with the company's vision. Aesthetics, form and function matter. PMID:16333871

Medenbach, James J

2005-11-01

449

Korea space program  

NASA Astrophysics Data System (ADS)

Though Korea's space activities are just in the infant stage, we are looking forward to joining the advanced countries in the space field. We have three on-going space programs: the KOREASAT Program, a sounding rocket program, and the KITSAT Program. And, we have three more programs that we are in the process of formulating: a small remote sensing satellite program, a data receiving station construction program, and the second generation KOREASAT program. We have several organizations which are involved with space-related activities: KARI, ETRI, SERI, and KAIST. KARI was founded in 1989 in accordance with the Aerospace Industry Development & Promotion Act for the purpose of conducting research on aicraft, satellites and scientific rockets, and supporting national aerospace development projects.

Hong, Jai-Hak

450

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

451

The Deep Space Network  

NASA Technical Reports Server (NTRS)

Progress on the Deep Space Network (DSN) supporting research and technology, advanced development, engineering and implementation, and DSN operations is presented. The functions and facilities of the DSN are described.

1979-01-01

452

Space tug thermal control  

NASA Technical Reports Server (NTRS)

The future development of full capability Space Tug will impose strict requirements upon the thermal design. While requiring a reliable and reusable design, Space Tug must be capable of steady-state and transient thermal operation during any given mission for mission durations of up to seven days and potentially longer periods of time. Maximum flexibility and adaptability of Space Tug to the mission model requires that the vehicle operate within attitude constraints throughout any specific mission. These requirements were translated into a preliminary design study for a geostationary deploy and retrieve mission definition for Space Tug to determine the thermal control design requirements. Results of the study are discussed with emphasis given to some of the unique avenues pursued during the study, as well as the recommended thermal design configuration.

Ward, T. L.

1975-01-01

453

The deep space network  

NASA Technical Reports Server (NTRS)

A report is given of the Deep Space Networks progress in (1) flight project support, (2) tracking and data acquisition research and technology, (3) network engineering, (4) hardware and software implementation, and (5) operations.

1979-01-01

454

The deep space network  

NASA Technical Reports Server (NTRS)

A Deep Space Network progress report is presented dealing with in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations.

1977-01-01

455

NOAA's Space Environment Center  

NSDL National Science Digital Library

National Oceanic & Atmospheric Administration's (NOAA's) Space Environment Center now offers a WWW server provides today's solar weather including a current solar image, x-ray and proton plots from GOES satellites, and the latest forecast of solar-terrestial conditions.

456

Envisioning creative space  

E-print Network

This thesis proposes a framework to articulate certain criteria in creative spatial productions such as architecture. I discuss that a conformist and unquestioning adaptation to conventional space conceptions limits ...

Özkâr, Mine, 1976-

1999-01-01

457

Saving Space in China  

E-print Network

Broadcast Transcript: The Chinese are geniuses at utilizing every inch of space. In a country that is historically overcrowded, this skill is important for survival. Chinese vegetable gardens are miracles of permaculture layout: small plants nestle...

Hacker, Randi

2013-09-09

458

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

459

The Deep Space Network  

NASA Technical Reports Server (NTRS)

The various systems and subsystems are discussed for the Deep Space Network (DSN). A description of the DSN is presented along with mission support, program planning, facility engineering, implementation and operations.

1977-01-01

460

Outlook for space  

NASA Technical Reports Server (NTRS)

Future space activities within the context of national needs were examined, and directions that the United States should take in the civilian use and exploration of space for the time period from 1980 to 2000 were identified. It was decided that the following activities should be pursued: (1) those related to the continuing struggle to improve the quality of life (food production and distribution, new energy sources, etc., (2) those meeting the need for intellectual challenge, for exploration, and for the knowledge by which man can better understand the universe and his relationship to it, (3) those related to research and development in areas applicable to future space systems and missions. A continuing emphasis should be placed on orienting the space program to the physical needs of mankind, to the quest of the mind and spirit, to the vitality of the nation and to the relationship between this nation and other nations of the world.

1976-01-01

461

A Nanotube Space Elevator  

NSDL National Science Digital Library

In this video adapted from NOVA scienceNOW, find out about the discovery of a new building material, the carbon nanotube, whose physical properties could theoretically enable the creation of a 22,000-mile elevator to space.

WGBH Educational Foundation

2008-09-08

462

Commutators on Banach Spaces  

E-print Network

. In particular, we will focus our attention to the spaces $\\lambda I and $\\linf$. The main results are that the commutators on $\\ell_1$ are the operators not of the form $\\lambda I + K$ with $\\lambda\

Dosev, Detelin

2010-10-12

463

Earth study from space  

NASA Technical Reports Server (NTRS)

The significance that space studies are making to all Earth sciences in the areas of geography, geodesy, cartography, geology, meteorology, oceanology, agronomy, and ecology is discussed. It is predicted that cosmonautics will result in a revolution in science and technology.

Sidorenko, A. V.

1981-01-01

464

Space Suit Spins  

NASA Technical Reports Server (NTRS)

Space is a hostile environment where astronauts combat extreme temperatures, dangerous radiation, and a near-breathless vacuum. Life support in these unforgiving circumstances is crucial and complex, and failure is not an option for the devices meant to keep astronauts safe in an environment that presents constant opposition. A space suit must meet stringent requirements for life support. The suit has to be made of durable material to withstand the impact of space debris and protect against radiation. It must provide essential oxygen, pressure, heating, and cooling while retaining mobility and dexterity. It is not a simple article of clothing but rather a complex modern armor that the space explorers must don if they are to continue exploring the heavens

2005-01-01

465

Future space transport  

NASA Technical Reports Server (NTRS)

Prospects for the mastery of space and the basic problems which must be solved in developing systems for both manned and cargo spacecraft are examined. The achievements and flaws of rocket boosters are discussed as well as the use of reusable spacecraft. The need for orbiting satellite solar power plants and related astrionics for active control of large space structures for space stations and colonies in an age of space industrialization is demonstrated. Various forms of spacecraft propulsion are described including liquid propellant rocket engines, nuclear reactors, thermonuclear rocket engines, electrorocket engines, electromagnetic engines, magnetic gas dynamic generators, electromagnetic mass accelerators (rail guns), laser rocket engines, pulse nuclear rocket engines, ramjet thermonuclear rocket engines, and photon rockets. The possibilities of interstellar flight are assessed.

Grishin, S. D.; Chekalin, S. V.

1984-01-01