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1

Magnetic field in galaxies, galaxy clusters, and intergalactic space  

SciTech Connect

Magnetic fields of unknown origin appear to permeate the Universe on all large scales. We suggest that the winds and cosmic rays, which are produced by the spherical ejecta and jets from supernova explosions, magnetize the interstellar medium in galaxies, the intracluster medium in galaxy clusters, and the intergalactic space. We show that, if the cosmic rays generate magnetic fields in rough energy equipartition with the cosmic rays, the predicted magnetic-field strengths coincide with the ones observed.

Dar, Arnon; Rujula, A. de [Department of Physics and Space Research Institute, Technion, Haifa 32000, Israel and Theory Unit, CERN, 1211 Geneva 23 (Switzerland); Theory Unit, CERN, 1211 Geneva 23 (Switzerland) and Physics Department, Boston University, Boston, Massachusetts (United States)

2005-12-15

2

The Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The intergalactic medium has contained, and still does, most of the matter in the universe. Galaxies form out of matter that originates from the intergalactic medium. The radiation from stars in galaxies plays an essential role in writing the ionization and thermal histories of the intergalactic medium. Galaxies return matter back to the intergalactic medium in the form of galactic winds powered by stellar winds and supernova explosions that in addition transport energy and metals. The various forms of feedback exerted on the intergalactic medium by galaxies have profound effects on subsequent galaxy formation. This two-way interaction between galaxies and the intergalactic medium is the primary driver of the formation and evolution of both. This chapter synthesizes our current knowledge of this interaction, focusing mainly on the evolution of the intergalactic medium. While it covers the entire redshift range from z = 1,100 to z = 0, the content is heavily skewed toward lower redshift, reflecting the current state of knowledge.

Cen, Renyue

3

Suprathermal grains - On intergalactic magnetic fields  

Microsoft Academic Search

The assumption is made that high-energy (at least 10 to the 18th eV) cosmic-ray particles are charged dust grains of intergalactic origin. It is suggested that dust grains may attain relativistic energy if magnetic fields are present in intergalactic space and that graphite dust grains with radii of 30 to 300 nm have the best chance to achieve relativistic energies

A. K. Dasgupta

1979-01-01

4

Suprathermal grains: On intergalactic magnetic fields  

Microsoft Academic Search

Charged dust grains of radiia?3×10-6~3×10-5 cm may be driven out of the galaxy due to radiation pressure of starlight. Once clear of the main gas-dust layer, dust grains may then escape into intergalactic space. Such grains are virtually indestructible-being evaporated only during galaxy formation. The dust grains, once injected into the intergalactic medium, may acquire suprathermal energy, thus ‘suprathermal grains’

Ajoy Kumar Dasgupta

1979-01-01

5

The physics and early history of the intergalactic medium  

Microsoft Academic Search

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

Rennan Barkana; Abraham Loeb

2007-01-01

6

Simulating intergalactic quasar scintillation  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

7

Large scale alignments in quasar polarizations due to pseudoscalar-photon mixing in intergalactic magnetic fields  

Microsoft Academic Search

We consider the propagation of visible radiation from quasars located at cosmological distances in intergalactic space, taking pseudoscalar-photon mixing into account. We assume that the intergalactic magnetic field is uncorrelated in the wave vector space such that the two point correlation function shows a power dependence on the magnitude of the wave vector. This leads to correlated magnetic field in

Nishant Agarwal; Pavan K. Aluri; Pankaj Jain; Udit Khanna; Prabhakar Tiwari

2011-01-01

8

Interstellar and intergalactic dynamos  

NASA Astrophysics Data System (ADS)

We review recent developments of amplification models of galactic and intergalactic magnetic field. The most popular scenarios involve variety of physical mechanisms, including turbulence generation on a wide range of physical scales, effects of supernovae, buoyancy as well as the magnetorotational instability. Other models rely on galaxy interaction, which generate galactic and intergalactic magnetic fields during galaxy mergers. We present also global galactic-scale numerical models of the Cosmic Ray (CR) driven dynamo, which was originally proposed by Parker (1992). We conduct a series of direct CR+MHD numerical simulations of the dynamics of the interstellar medium (ISM), composed of gas, magnetic fields and CR components. We take into account CRs accelerated in randomly distributed supernova (SN) remnants, and assume that SNe deposit small-scale, randomly oriented, dipolar magnetic fields into the ISM. The amplification timescale of the large-scale magnetic field resulting from the CR-driven dynamo is comparable to the galactic rotation period. The process efficiently converts small-scale magnetic fields of SN-remnants into galactic-scale magnetic fields. The resulting magnetic field structure resembles the X-shaped magnetic fields observed in edge-on galaxies.

Hanasz, M.; Woltanski, D.; Kowalik, K.

2013-07-01

9

Intergalactic magnetic fields and implications for CR and gamma ray astronomy  

Microsoft Academic Search

I briefly discuss methods for detecting and measuring magnetic fields in interstellar and intergalactic space. Some recent results are illustrated for magnetic fields in the Milky Way, galaxy outflow halos, galaxy clusters and the intergalactic medium beyond clusters. The general trend of recent observations is that magnetic fields at significant strengths are increasingly found to be present in the diffuse

Philipp P. Kronberg

2001-01-01

10

Simulating intergalactic medium reionization  

NASA Astrophysics Data System (ADS)

We have studied the intergalactic medium (IGM) reionization process in its full cosmological context, including structure evolution and a realistic galaxy population. We have used a combination of high-resolution N-body simulations (to describe the dark matter and diffuse gas component), a semi-analytical model of galaxy formation (to track the evolution of the sources of ionizing radiation) and the Monte Carlo radiative transfer code CRASH (to follow the propagation of ionizing photons into the IGM). The process has been followed in the largest volume ever used for this type of study, a field region of the Universe with a comoving length of L~ 20 h-1 Mpc, embedded in a much larger cosmological simulation. To assess the effect of environment on the reionization process, the same radiative transfer simulations have been performed on a 10 h-1 Mpc comoving box, centred on a clustered region. We find that, to account for the all-ionizing radiation, objects with total masses of M~ 109 Msolar must be resolved. In this case, the simulated stellar population produces a volume-averaged ionization fraction xv= 0.999 by z~ 8, consistent with observations without requiring any additional sources of ionization. We also find that environment substantially affects the reionization process. In fact, although the simulated protocluster occupies a smaller volume and produces a higher number of ionizing photons, it becomes totally ionized later. This is because high-density regions, which are more common in the protocluster, are difficult to ionize because of their high recombination rates.

Ciardi, B.; Stoehr, F.; White, S. D. M.

2003-08-01

11

Determination of intergalactic magnetic fields from gamma ray data  

Microsoft Academic Search

We report a measurement of intergalactic magnetic fields using combined data from Atmospheric Cherenkov Telescopes and Fermi Gamma-Ray Space Telescope, based on the spectral data alone. If blazars are assumed to produce both gamma rays and cosmic rays, the observed spectra are not sensitive to the intrinsic spectrum of the source, because, for a distant blazar, secondary photons produced along

Warren Essey; Shin’ichiro Ando; Alexander Kusenko

2011-01-01

12

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

13

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

14

Determination of intergalactic magnetic fields from gamma ray data  

Microsoft Academic Search

We report a measurement of intergalactic magnetic fields using combined data\\u000afrom Atmospheric Cherenkov Telescopes and Fermi Gamma-Ray Space Telescope,\\u000abased on the spectral data alone. If blazars are assumed to produce both gamma\\u000arays and cosmic rays, the observed spectra are not sensitive to the intrinsic\\u000aspectrum of the source, because, for a distant blazar, secondary photons\\u000aproduced in

Warren Essey; Shin'ichiro Ando; Alexander Kusenko

2010-01-01

15

Is the intergalactic magnetic field primordial?  

Microsoft Academic Search

We consider the various methods used to constrain the possible field strength of the present day intergalactic field and findB0(G)-10 as a probable upper bound. It is suggested that the observed intergalactic magnetic field might not be primordial in origin but rather the result of magnetic flux leakage from galaxies and clusters of galaxies.

Martin Beech

1985-01-01

16

Is the intergalactic magnetic field primordial?  

NASA Astrophysics Data System (ADS)

The various methods used to constrain the possible field strength of the present day intergalactic field are considered, and Bzero (G) less than 10 to the -10th is found as a probable upper bound. It is suggested that the observed intergalactic magnetic field might not be primordial in origin but rather the result of magnetic flux leakage from galaxies and clusters of galaxies.

Beech, M.

1985-11-01

17

Galactic and intergalactic Faraday rotation  

NASA Astrophysics Data System (ADS)

A model of the systematic component of the magnetic field of the Galaxy is fitted to a sample of 459 extragalactic rotation measures (RM), and the results are found to be consistent with a previous analysis of pulsar RMs by Thomson and Nelson (1980). The model is then used to reduce the effect of galactic Faraday rotation on the RMs of 134 QSOs, and the results used to investigate the existence of a Faraday-active intergalactic medium. Three models are considered in order to explain the redshift dependence of the RM variance. Although none of these models can be excluded, a significant fraction of the observed Faraday rotation may take place in extended cluster/supercluster haloes with dimensions about 9 Mpc, electron densities about 0.0001/cu cm and magnetic fields about 0.1-1 microgauss. The inferred filling-factor, about 0.002, implies omega of about 0.1.

Thomson, R. C.; Nelson, A. H.

1982-10-01

18

Ionization History of The Intergalactic Medium:.  

National Technical Information Service (NTIS)

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 th...

P. Madau

2003-01-01

19

Intergalactic magnetic fields, and some connections with cosmic rays  

Microsoft Academic Search

An overview is presented of the methods of probing for the geometry, and strength of intergalactic magnetic fields. Recent results are briefly surveyed for galaxy halos, galaxy clusters, and the intergalactic medium on various scales, and some rele vant physical processes and radiation processes are mentioned, as well as the “coupling” between intergalactic magnetic fields and cosmic rays.

Philipp P. Kronberg

1996-01-01

20

Simulating the Effects of Intergalactic Gray Dust.  

PubMed

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

Croft; Davé; Hernquist; Katz

2000-05-10

21

Intergalactic magnetic field and galactic WARPS  

Microsoft Academic Search

An alternative explanation of galactic warps is proposed, in which the intergalactic magnetic field (IGMF) is responsible for these structures. The model predicts that, to be efficient, the magnetic field must have a direction not much different from 45 deg with the galactic plane. The required values of the field strength are uncertain, of about 10 nG, higher values being

E. Battaner; E. Florido; M. L. Sanchez-Saavedra

1990-01-01

22

Intergalactic Magnetic Fields from Quasar Outflows  

Microsoft Academic Search

Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and calculate their distribution as a function of size and magnetic field strength at different redshifts. We generically find that by a redshift z~3,

Steven R. Furlanetto; Abraham Loeb

2001-01-01

23

Grain alignment in the intergalactic magnetic field  

Microsoft Academic Search

Processes for grain alignment in the intergalactic magnetic field are considered: evidence is examined for grains being spun up to extremely high (109 Hz) angular frequencies by the recoil of hydrogen recombination on grains, as an essential part of the alignment process. Grain alignment would then be inhibited in region of grain growth and would be most effective where grain

Ajoy K. Dasgupta

1983-01-01

24

a Search for Intergalactic Stars in the Local Group  

NASA Astrophysics Data System (ADS)

A profound change in our picture of the Local Group has been suggested by Blitz et al. {1998}, who argue that dex11 M{sun} of HI resides in a long filament between the Milky Way and M 31, which they identify with the HI high-velocity clouds {HVCs}. Since many HVCs are known to contain heavy elements {with a metallicity of >0.01 times solar}, a critical test of the model is to find the evolved stars within the population that produced these heavy elements. We propose to search for these stars. Since the model of Blitz et al. {1998} predicts HVC distances of >100 kpc, the stars will be faint {V>24}. However, we show that they can be found using starcounts on WFPC2 images, provided that the space density exceeds 1/1000 that in the solar neighborhood, Detecting intergalactic stars in the HI filament would allow a determination of the distance to the HVCs, and establish the presence of a completely new component of the Local Group. A negative result would allow stringent limits to be set on the number of intergalactic stars and on models for HVCs.

Wakker, Bart

1999-07-01

25

An Intergalactic Magnetic Field from Quasar Outflows  

Microsoft Academic Search

Outflows from quasars inevitably pollute the intergalactic medium (IGM) with\\u000amagnetic fields. The short-lived activity of a quasar leaves behind an\\u000aexpanding magnetized bubble in the IGM. We model the expansion of the remnant\\u000aquasar bubbles and calculate their distribution as a function magnetic field\\u000astrength at different redshifts. We find that by a redshift z ~ 3, about 5-80%

Steven R. Furlanetto; Abraham Loeb

2001-01-01

26

Intergalactic Magnetic Fields from Quasar Outflows  

Microsoft Academic Search

Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of\\u000a a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and\\u000a calculate their distribution as a function magnetic field strength at different redshifts. We find that by a redshift \\u000a z ~ <\\/font\\u000a>3z \\\\sim

Steven Furlanetto; Abraham Loeb

2002-01-01

27

Intergalactic magnetic fields in Stephan's Quintet  

NASA Astrophysics Data System (ADS)

We present the results from the Very Large Array radio continuum total power and polarized intensity observations of Stephan's Quintet at 1.43 and 4.86 GHz, along with complementary 4.85- and 8.35-GHz Effelsberg observations. Our study shows a large envelope of radio emission encompassing all the member galaxies and hence a large volume of intergalactic matter. Infall of the galaxy NGC 7318B produces a ridge of intergalactic, polarized emission, for which the magnetic field strength has been estimated as 11.0 ± 2.2 ?G, with an ordered component of 2.6 ± 0.8 ?G. The energy density of the field within the ridge area is of the same order as estimates of the thermal component, implying that the magnetic field has a significant role in the dynamics of the intergalactic matter. We also report that the tidal dwarf galaxy candidate SQ-B possesses a strong and highly anisotropic magnetic field, with a total strength equal to 6.5 ± 1.9 ?G and an ordered component reaching 3.5 ± 1.2 ?G, which is comparable to that found in normal-sized galaxies.

Nikiel-Wroczy?ski, B.; Soida, M.; Urbanik, M.; Beck, R.; Bomans, D. J.

2013-10-01

28

Do intergalactic magnetic fields imply an open universe?  

NASA Astrophysics Data System (ADS)

The detection of magnetic fields at high redshifts, and in empty intergalactic space, supports the idea that cosmic magnetism has a primordial origin. Assuming that Maxwellian electromagnetism and general relativity hold, and without introducing any new physics, we show how the observed magnetic fields can easily survive cosmological evolution from the inflationary era in a marginally open Friedmann universe but fail to do so, by a very wide margin, in a flat or a marginally closed universe. Magnetic fields evolve very differently in open and closed Friedmann models. The existence of significant magnetic fields in the universe today, that require primordial seeding, may therefore provide strong evidence that the universe is marginally open rather than marginally closed.

Barrow, John D.; Tsagas, Christos G.; Yamamoto, Kei

2012-11-01

29

A search for intergalactic neutral hydrogen in three nearby groups of galaxies  

Microsoft Academic Search

Results are reported for a systematic unbiased search with a 40-m telescope for 21-cm H I emission from intergalactic space in three nearby groups of galaxies, as well as for a higher-sensitivity search with a 100-m telescope in selected areas of the same groups. The search covered over 300 sq deg of arc in the M81, CVn I, and NGC

K. Y. Lo; W. L. W. Sargent

1979-01-01

30

Using Gamma Rays as Intergalactic Magnetometers  

NASA Astrophysics Data System (ADS)

Gamma rays from distant blazars interact with the extragalactic background light, creating electron-positron pairs, and reducing the amount of gamma-rays seen by ground-based atmospheric Cherenkov telescopes. These pairs can Compton-scatter the cosmic microwave background, creating a gamma-ray signature observable by the Fermi Large Area Telesope (LAT). The signature is also dependent on the intergalactic magnetic field (IGMF), since it can deflect the pairs from our line of sight, reducing the gamma-ray emission. We present preliminary constraints on the IGMF using Fermi-LAT and Cherenkov telescope observations, ruling out both very large and very small values of the IGMF strength.

Finke, Justin; Reyes, L. C.; Georganopoulos, M.; Fermi-LAT Collaboration

2013-04-01

31

Intergalactic magnetic fields and the periphery of spiral galaxies  

Microsoft Academic Search

The present consideration of the effect of intergalactic magnetic fields on the peripheral shape of a spiral galaxy notes that the magnetic field contained in the galactic plane generates an elliptical shape in the outer regions; the most external isophote is more eccentric than the inner isophotes. While it is difficult to identify this shape in actual galaxies, the intergalactic

E. Battaner; E. Florido; M. L. Sanchez-Saavedra

1992-01-01

32

A New Way of Detecting Intergalactic Baryons  

NASA Astrophysics Data System (ADS)

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

2013-02-01

33

Intergalactic Helium Absorption in Cold Dark Matter Models  

NASA Astrophysics Data System (ADS)

Observations from the Hopkins Ultraviolet Telescope and the Hubble Space Telescope have recently detected He II absorption along the lines of sight to two high-redshift quasars. We use cosmological simulations with gas dynamics to investigate He II absorption in the cold dark matter (CDM) theory of structure formation. We consider two Omega = 1 CDM models with different normalizations and one open universe ( Omega 0 = 0.4) CDM model. The simulations incorporate the photoionizing UV background spectrum computed by Haardt & Madau, which is based on the output of observed quasars and reprocessing by the Ly alpha forest. The simulated gas distribution, combined with the Haardt & Madau spectral shape, accounts for the relative observed values of tau bar H I and tau bar He II, the effective mean optical depths for H I and He II absorption. If the background intensity is as high as Haardt & Madau predict, then matching the absolute observed values of tau bar H I and tau bar He II requires a baryon abundance larger (by factors between 1.5 and 3 for the various CDM models) than our assumed value of Omega bh2 = 0.0125. The simulations reproduce the evolution of tau bar He II over the observed redshift range, 2.2 <~ z <~ 3.3, if the He II photoionization rate remains roughly constant. He II absorption in the CDM simulations is produced by a diffuse, fluctuating, intergalactic medium, which also gives rise to the H I Ly alpha forest. Much of the He II opacity arises in underdense regions where the H I optical depth is very low. We compute statistical properties of the He II and H I absorption that can be used to test the CDM models and distinguish them from an alternative scenario in which the He II absorption is caused by discrete, compact clouds. The CDM scenario predicts that a substantial amount of baryonic material resides in underdense regions at high redshift. He II absorption is the only sensitive observational probe of such extremely diffuse, intergalactic gas, so it can provide a vital test of this fundamental prediction.

Croft, Rupert A. C.; Weinberg, David H.; Katz, Neal; Hernquist, Lars

1997-10-01

34

Resistive Generation of Intergalactic Magnetic Field at Cosmic Dawn  

NASA Astrophysics Data System (ADS)

Miniati & Bell (2011) proposed a mechanism for the generation of magnetic seeds that is based the finite resistivity of the low temperature IGM in the high redshift universe. In this model, cosmic-ray protons generated by the first generation of galaxies, escape into the intergalactic medium carrying an electric current that induces return currents, jt, and associated electric fields, E = ?jt there. Because the resistivity, ?, depends on the IGM temperature, which is highly inhomogeneous due to adiabatic contraction and shocks produced by structure formation, a non-vanishing curl of the electric field exists which sustains the growth of magnetic field. In this contribution we have developed an approximate numerical model for this process by implementing the source terms of the resistive mechanism in the cosmological code CHARM. Our numerical estimates substantiate the earlier analysis in Miniati & Bell (2011) which found magnetic seeds between 10-18 and 10-16 Gauss throughout cosmic space at redshift z ˜ 6, consistent with conservative estimates of magnetic fields in voids at z ˜ 0 from recent gamma-ray experiments.

Miniati, F.; Bell, A. R.

2012-07-01

35

Intergalactic stellar populations in intermediate redshift clusters  

NASA Astrophysics Data System (ADS)

A substantial fraction of the total stellar mass in rich clusters of galaxies resides in a diffuse intergalactic component usually referred to as the intracluster light (ICL). Theoretical models indicate that these intergalactic stars originate mostly from the tidal interaction of the cluster galaxies during the assembly history of the cluster, and that a significant fraction of these stars could have formed in situ from the late infall of cold metal-poor gas clouds on to the cluster. However, these models also overpredict the fraction of stellar mass in the ICL by a substantial margin, something that is still not well understood. The models also make predictions about the age distribution of the ICL stars, which may provide additional observational constraints. Here we present population synthesis models for the ICL of an intermediate redshift (z = 0.29) X-ray cluster that we have extensively studied in previous papers. The advantage of observing intermediate redshift clusters rather than nearby ones is that the former fit the field of view of multi-object spectrographs in 8-m telescopes and therefore permit us to encompass most of the ICL with only a few well-placed slits. In this paper we show that by stacking spectra at different locations within the ICL it is possible to reach sufficiently high signal-to-noise ratios to fit population synthesis models and derive meaningful results. The models provide ages and metallicities for the dominant populations at several different locations within the ICL and the brightest cluster galaxies (BCG) halo, as well as measures of the kinematics of the stars as a function of distance from the BCG. We thus find that the ICL in our cluster is dominated by old metal-rich stars, at odds with what has been found in nearby clusters where the stars that dominate the ICL are old and metal poor. While we see weak evidence of a young, metal-poor component, if real, these young stars would amount to less than 1 per cent of the total ICL mass, much less than the up to 30 per cent predicted by the models. We propose that the very metal-rich (i.e. 2.5× solar) stars in the ICL of our cluster, which comprise ˜40 per cent of the total mass, originate mostly from the central dumb-bell galaxy, while the remaining solar and metal-poor stars come from spiral, post-starburst (E+A) and metal-poor dwarf galaxies. About 16 per cent of the ICL stars are old and metal poor.

Melnick, J.; Giraud, E.; Toledo, I.; Selman, F.; Quintana, H.

2012-11-01

36

Particle energy cascade in the intergalactic medium  

NASA Astrophysics Data System (ADS)

We study the development of high-energy (Ein <= 1 TeV) cascades produced by a primary electron of energy Ein injected into the intergalactic medium (IGM). To this aim we have developed the new code MEDEA (Monte Carlo Energy Deposition Analysis) which includes Bremsstrahlung and inverse Compton (IC) processes, along with H/He collisional ionizations and excitations, and electron-electron collisions. The cascade energy partition into heating, excitations and ionizations depends primarily not only on the IGM ionized fraction, xe, but also on redshift, z, due to IC on cosmic microwave background (CMB) photons. While Bremsstrahlung is unimportant under most conditions, IC becomes largely dominant at energies Ein >= 1 MeV. The main effect of IC at injection energies Ein <= 100 MeV is a significant boost of the fraction of energy converted into low-energy photons (h? < 10.2 eV) which do not further interact with the IGM. For energies Ein >= 1 GeV CMB photons are preferentially upscattered within the X-ray spectrum (h? > 104 eV) and can free stream to the observer. Complete tables of the fractional energy depositions as a function of redshift, Ein and ionized fraction are given. Our results can be used in many astrophysical contexts, with an obvious application related to the study of decaying/annihilating dark matter (DM) candidates in the high-z Universe.

Valdés, M.; Evoli, C.; Ferrara, A.

2010-05-01

37

Constraints on the intergalactic magnetic field from gamma-ray observations of TeV blazars  

NASA Astrophysics Data System (ADS)

We discuss different approaches to infer the properties of the intergalactic magnetic field (IGMF) from gamma-ray observations of blazars. In particular, we investigate constraints on the IGMF strength and spacial distribution, resulting from studies of TeV blazars by imaging atmospheric Cherenkov telescopes and the Fermi-LAT instrument. We demonstrate that the non-observation of GeV gamma-rays from powerful TeV blazars indicates that more than 60% of space is filled by magnetic fields with stength gtrsim 10-15 G, favoring the primordial IGMF origin.

Kachelrieß, M.; Ostapchenko, S.; Tomàs, R.

2012-07-01

38

THEIA: Telescope for Habitable Exoplanets and Interstellar/Intergalactic Astronomy  

NASA Astrophysics Data System (ADS)

Over the past 25 years, the Hubble Space Telescope has revolutionized our view of the universe, excited and engaged the general public with its compelling images, and has been a workhorse for astrophysics. We propose that NASA build THEIA, Telescope for Habitable Exoplanets and Interstellar/Intergalactic Astronomy, a flagship 4-meter on-axis optical/UV telescope as a worthy successor to HST and companion to the James Webb Space Telescope (JWST). With a wide field imager, an ultraviolet spectrograph, a planet imager/spectrograph and a companion occulter, THEIA is capable of addressing many of the most important questions in astronomy: Are we alone? Are there other habitable planets? How frequently do solar systems form and survive? How do stars and galaxies form and evolve? How is dark matter distributed in galaxies and in the filaments? Where are most of the atoms in the universe? How were the heavy elements necessary for life created and distributed through cosmic time? This poster describes the THEIA Observatory, an on-axis three-mirror anastigmat telescope with a 4-meter Al/MgF2-coated primary, an Al/LiF-coated secondary and three main instruments: Star Formation Camera (SFC), a dual-channel wide field UV/optical imager covering 19’ x 15’ on the sky with 18 mas pixels; UltraViolet Spectrograph (UVS) , a a multipurpose spectrometer optimized for high sensitivity observations of faint astronomical sources at spectral resolutions of 30,000 to 100,000 in the 100-300 nm wavelength range; and eXtrasolar Planet Characterizer (XPC), which consists of three narrow-field cameras (250-400 nm; 400-700 nm; 700-1000 nm) and two R/70 integral field spectrographs (IFS).

Spergel, David N.; THEIA Collaboration

2010-01-01

39

VORTICITY OF INTERGALACTIC MEDIUM VELOCITY FIELD ON LARGE SCALES  

SciTech Connect

We investigate the vorticity of the intergalactic medium (IGM) velocity field on large scales with cosmological hydrodynamic simulation of the concordance model of LAMBDACDM. We show that the vorticity field is significantly increasing with time as it can effectively be generated by shocks and complex structures in the IGM. Therefore, the vorticity field is an effective tool to reveal the nonlinear behavior of the IGM, especially the formation and evolution of turbulence in the IGM. We find that the vorticity field does not follow the filament and sheet structures of the underlying dark matter density field and shows highly non-Gaussian and intermittent features. The power spectrum of the vorticity field is then used to measure the development of turbulence in Fourier space. We show that the relation between the power spectra of vorticity and velocity fields is perfectly in agreement with the prediction of a fully developed homogeneous and isotropic turbulence in the scale range from 0.2 to about 3 h {sup -1} Mpc at z {approx} 0. This indicates that the cosmic baryonic field is in the state of fully developed turbulence on scales less than about 3 h {sup -1} Mpc. The random field of the turbulent fluid yields turbulent pressure to prevent the gravitational collapsing of the IGM. The vorticity and turbulent pressure are strong inside and even outside of high density regions. In IGM regions with 10 times mean overdensity, the turbulent pressure can be on an average equivalent to the thermal pressure of the baryonic gas with a temperature of 1.0 x 10{sup 5} K. Thus, the fully developed turbulence would prevent the baryons in the IGM from falling into the gravitational well of dark matter halos. Moreover, turbulent pressure essentially is dynamical and non-thermal, which makes it different from a pre-heating mechanism, as it does not affect the thermal state and ionizing process of hydrogen in the IGM.

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

2010-03-20

40

A photon rest mass and intergalactic magnetic fields  

Microsoft Academic Search

Conditions for the existence and stability of the currents which would be required to support an intergalactic magnetic field are examined to see what upper limit could be obtained for the photon rest mass if the existence of such a field is established.

R. R. Burman; J. C. Byrne

1973-01-01

41

Seeding of Intergalactic Magnetic Fields by Primeval Galaxies  

Microsoft Academic Search

We apply what has been recently learned from starburst - driven ``superwinds,'' dwarf galaxy surveys, and galaxy merging scenarios, to demonstate how a substantial fraction of the intergalactic medium can be permeated by magnetized outflow material from the ``volcanic early universe.'' Galactic wind outflow scenarios have been parameterized in model calculations that are embedded in different cosmological scenarios, in which

P. P. Kronberg; H. Lesch; U. Hopp

1998-01-01

42

Intergalactic magnetic fields and Faraday rotation of extragalactic radio sources  

Microsoft Academic Search

This paper reexamines our earlier statistical analyses of rotation measures RM and redshifts z of extragalactic radio sources. Absolute magnitudes of RM of 97 sources at high galactic latitudes, |b| > 35°, are shown to increase with z. Correlation coefficients r between RM and z cos theta are calculated for various presumed directions of the intergalactic magnetic field, where theta

Y. Sofue; M. Fujimoto; K. Kawabata

1979-01-01

43

Faraday Rotation Measure Due to the Intergalactic Magnetic Field  

Microsoft Academic Search

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

Takuya Akahori; Dongsu Ryu

2010-01-01

44

Bent-Double Radio Sources as Probes of Intergalactic Gas  

Microsoft Academic Search

As the most common environment in the universe, groups of galaxies are likely to contain a significant fraction of the missing baryons in the form of intergalactic gas. The density of this gas is an important factor in whether ram pressure stripping and strangulation affect the evolution of galaxies in these systems. We present a method for measuring the density

Emily E. Freeland; F. Cardoso; E. Wilcots

2009-01-01

45

Lyman-alpha absorption spectrum of the primordial intergalactic medium  

Microsoft Academic Search

The Ly-alpha absorption by four intergalactic medium (IGM) distribution models in the cold dark matter cosmology is simulated, taking the role of the Doppler effect of the peculiar velocity into account. It is found that the medium can produce forestlike Ly-alpha absorption spectra compatible with those observed by fitting statistically the probability distribution function of the line equivalent width and

Hongguang Bi

1993-01-01

46

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

47

Galactic structure and turbulence, pulsar distances, and the intergalactic medium  

NASA Astrophysics Data System (ADS)

This paper summarizes how multi-wavelength measurements will be aggregated to determine Galactic structure in the interstellar medium (ISM) and produce the next-generation electron density model. Fluctuations in density and magnetic field from parsec scales down to about 1000 km cause a number of propagation effects in both radio waves and cosmic rays. Density microstructure appears to include Kolmogorov-like turbulence. The next generation electron-density model, NE2012, will include about double the number of lines of sight with dispersion and scattering measurements and it will be anchored with a much larger number of pulsar parallax distances. The foreground Galactic model is crucial for inferring similar ionized structures in the intergalactic medium (IGM) from scattering measurements on high-z objects. Intergalactic scattering is discussed with reference to distant sources of radio bursts. In particular, the cosmological radio scattering horizon is defined along with its analog for the ISM.

Cordes, J. M.

2013-03-01

48

Intergalactic Dust and Observations of Type IA Supernovae  

Microsoft Academic Search

Estimates of the cosmic star formation rate and of cluster metallicities independently imply that at z<~0.5 the gas in the universe has substantial average metallicity: 1\\/10<~Z\\/Zsolar<~1\\/3 for Omegagas=0.05. This metal density probably cannot be contained in known solar-metallicity galaxies of density parameter Omega*~0.004, implying significant enrichment of the intergalactic medium (IGM) by ejection of metals and dust from galaxies via

Anthony N. Aguirre

1999-01-01

49

Intergalactic and galactic magnetic fields - an updated test  

Microsoft Academic Search

The redshift dependence of the rotation measures of 142 sources (with known redshift and located in the southern galactic hemisphere) places an upper limit of 4 rad. m-2 to the contribution of a homogeneous magnetic field in the intergalactic medium (outside clusters of galaxies) out to a redshift z of 2.2. From this result, an upper limit of 3×10-11 gauss

J. P. Vallee

1983-01-01

50

Measuring the equation of state of the intergalactic medium  

Microsoft Academic Search

Numerical simulations indicate that the smooth, photoionized intergalactic medium (IGM) responsible for the low column density Lyalpha forest follows a well-defined temperature-density relation, which is well described by a power law TT0(rhorho)gamma-1. We demonstrate that such an equation of state results in a power-law cut-off in the distribution of linewidths (b-parameters) as a function of column density (N) for the

Joop Schaye; Tom Theuns; Anthony Leonard; George Efstathiou

1999-01-01

51

Constraining weak intergalactic magnetic fields: prospects for the Cherenkov Telescope Array  

NASA Astrophysics Data System (ADS)

In recent years the possibility of constraining weak intergalactic magnetic fields (IGMFs) has emerged through simultaneous spectral observations of blazars at very high energies (VHE) utilizing data from the Fermi Gamma Ray Space Telescope and the ground-based imaging atmospheric Cherenkov Telescopes (IACTs). In this submission we explore the capabilities of Fermi and CTA to advance such studies through the potential detection of gamma-ray halos around AGN and detection of delayed VHE radiation decaying after intense VHE flares of Flat Spectrum Radio Quasars (FSRQs), which have recently been observed from such astrophysical objects. CTA will be an effective tool for constraining the properties of the IGMF, due to its vastly increased collecting area, improved angular resolution, and wide field of view, all of which enhance its capability for the study of VHE transients and astrophysical source morphology.

Vassiliev, Vladimir; Arlen, Timothy

2012-07-01

52

COSMOLOGICAL X-RAY SCATTERING FROM INTERGALACTIC DUST  

SciTech Connect

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

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

2012-06-01

53

Intergalactic magnetic fields and time delays in pulses of gamma radiation  

Microsoft Academic Search

The detection of cosmological primordial magnetic fields would allow far-reaching conclusions about the physics of the early universe. These intergalactic fields are probably very weak today, and new ideas are necessary to allow their detection. One possibility is to measure gamma rays delayed by the action of an intergalactic field on cascaded electrons with respect to pulses of very high

R. Plaga

1994-01-01

54

On the origin of the intergalactic magnetic field and of the radio halo associated with the Coma cluster of galaxies  

Microsoft Academic Search

Intergalactic magnetic field can be created by the dynamo effect in the turbulent wake of galaxies moving in an intergalactic medium. The observed radio halo in the Coma cluster could be synchrotron radiation of relativistic electrons accelerated in situ in the intergalactic medium by fluctuations of the magnetic field created in the wake of the galaxies.

J. Roland

1981-01-01

55

Thermal diffusion in the intergalactic medium of clusters of galaxies  

NASA Astrophysics Data System (ADS)

We revisit the phenomenon of elements diffusion in the intergalactic medium (IGM) in clusters of galaxies. The diffusion is driven by gravity, concentration and temperature gradients. The latter cause thermal diffusion, which has been so far ignored in IGM studies. We consider the full problem based on the Burgers' equations and demonstrate that the temperature gradients present in clusters of galaxies may successfully compete with gravity, evacuating metals from cooler regions. Under the combined action of gravity and temperature gradients, complicated metallicity profiles with several peaks and depressions may be formed. For a typical cool core cluster, the thermal diffusion may significantly reduce and even reverse the gravitational sedimentation of metals, resulting in the depression in their abundance in the core. This may have implications for diagnostics of the low-temperature plasma in the centres of clusters of galaxies.

Shtykovskiy, P.; Gilfanov, M.

2010-01-01

56

Mass spectrum of the system of inhomogeneous intergalactic clouds.  

NASA Astrophysics Data System (ADS)

The possible influence of the internal structure of inter galactic clouds on their asymptotic mass spectrum n(m, t? ?) is investigated by numerically solving the Smoluchovski equation. Allowance for internal structure (inhomogeneity, fractality) leads to a relationship between cloud mass and radius of the type m oc Rk; values of the parameter k from the range [1.5, 3] were used in the calculations. Values of the slope q(k) of the asymptotic mass spectrum are obtained for different sections of the spectrum and different initial conditions n(m, t = 0). It is shown that the slope of the asymptotic spectrum depends strongly on the parameter k, which characterizes the degree of inhomogeneity of the mass distribution in the clouds. A self-consistent estimate of the fractal dimension of intergalactic clouds is obtained, improving the value found earlier.

Sokolov, A. S.

1997-10-01

57

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.

58

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

National Technical Information Service (NTIS)

The intergalactic magnetic field (IGMF) may leave an imprint on the anisotropy properties of the extragalactic gamma-ray background, through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragal...

T. M. Venters V. Pavlidou

2012-01-01

59

Limits on source distances for the most energetic cosmic rays in intergalactic magnetic fields  

Microsoft Academic Search

The propagation of the highest energy cosmic rays through the intergalactic magnetic field is considered, including the effect of interactions with the 2.7 K microwave background. Energy loss in the microwave background due to photo-pion production limits the total distance travelled by the cosmic rays and the turbulent intergalactic field determines their total displacement. At energies above 10^20 eV, the

R. Lampard; R. W. Clay; B. R. Dawson

1997-01-01

60

Limits on source distances for the most energetic cosmic rays in intergalactic magnetic fields  

Microsoft Academic Search

The propagation of the highest energy cosmic rays through the intergalactic magnetic field is considered, including the effect of interactions with the 2.7 K microwave background. Energy loss in the microwave background due to photo-pion production limits the total distance travelled by the cosmic rays and the turbulent intergalactic field determines their total displacement. At energies above 1020 eV, the

R. Lampard; R. W. Clay; B. R. Dawson

1997-01-01

61

3D Spatial Distribution of the Intergalactic Medium: The ESO Blues?  

NASA Astrophysics Data System (ADS)

The numerous absorption lines seen in the spectra of distant quasars (the so-called Lyman-? forest) reveal the intergalactic medium (IGM) up to redshifts larger than 5. It is believed that the space distribution of the gas traces the potential wells of the dark matter. Indeed, recent numerical N-body simulations have been successful at reproducing the observed characteristics of the Lyman-? forest (e.g. [1][12][5]). The IGM is therefore seen as a smooth pervasive medium which can be used to study the spatial distribution of the mass on scales larger than the Jeans' length. This idea is reinforced by observations of multiple lines of sight. It is observed that the Lyman-? forest is fairly homogeneous on scale smaller than 100 kpc (e.g. [11]) and highly correlated on scale up to one megaparsec (e.g. [13][3]). The number of suitable multiple lines of sight is small however and the sample need to be significantly enlarged before any firm conclusion can be drawn (see Section 3.3).

Rollinde, Emmanuel; Petitjean, Patrick; Pichon, Christophe; Colombi, Stéphane; Aracil, Bastien

62

Hard spectrum TeV blazars and intergalactic magnetic fields  

NASA Astrophysics Data System (ADS)

The intergalactic magnetic field (IGMF) in cosmic voids can be indirectly probed through its effect on electromagnetic cascades initiated by a source of TeV gamma rays, such as blazars, a subclass of active galactic nuclei. Blazars that are sufficiently luminous at TeV energies can produce secondary radiation from inverse Compton scattering of the electrons in the cascade, which can be observable provided that the IGMF is not too large. We reveiw recent work in the literature which utilizes this idea to derive constraints on the IGMF for three TeV-detected blazars-1ES 0229+200, 1ES 1218+304, and RGB J0710+591. Through a recently developed detailed Monte Carlo code, incorporating all major effects of QED and cosmological expansion, various systematic uncertainties in the modeling are highlighted and the implications on the lower limits are examined. It is shown that due to these uncertainties, a non-zero lower limit on the IGMF cannot be substantiated.

Arlen, Timothy C.; Vassiliev, Vladimir V.

2012-12-01

63

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)

1997-12-01

64

AKARI observations of the multiphase intergalactic medium of Stephan's Quintet  

NASA Astrophysics Data System (ADS)

Stephan's Quintet (SQ, HCG92) is a well studied compact group of galaxies with a disturbed intergalactic medium (IGM). An ``intruder'' galaxy NGC 7318b is currently colliding with the IGM at a relative velocity of 1000 km s-1, causing a large-scale shock front. We observed SQ with the Far-Infrared Surveyor (FIS) aboard AKARI in four far-infrared (far-IR) bands at 65, 90, 140, and 160?m. The 160?m image clearly shows an additional peak of emission overlying structure extending in the North-South direction along the shock ridge seen in the 140?m band, and in H2 and X-ray emission. Whereas most of the far-IR emission in the shocked region is from cold dust (20 K), the [CII]158?m emission - whose luminosity is comparable to that of the warm H2 gas - can significantly contribute to the single peak emission in the 160?m band. We conclude that the [CII] line emission comes from the warm H2 gas in the shock. Our result represents the first detection of shock-excited [CII] line emission.

Suzuki, Toyoaki; Kaneda, Hidehiro; Onaka, Takashi; Kitayama, Tetsu

2012-08-01

65

FARADAY ROTATION MEASURE DUE TO THE INTERGALACTIC MAGNETIC FIELD  

SciTech Connect

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 (B) {approx} 10 nG and a coherence length of several x 100 h {sup -1} kpc in filaments. With the coherence length smaller than the path length, the inducement of RM would be a random walk process, and we found that the density peak along the line of sight dominantly contributes to the resultant RM. The root mean square of RM through filaments at the present universe was predicted to be {approx}1 rad m{sup -2}. In addition, we predicted that the probability distribution function of |RM| through filaments follows the lognormal distribution, and the power spectrum of RM in the local universe peaks at a scale of {approx}1 h {sup -1} Mpc. Our prediction of RM could be tested with future instruments.

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

2010-11-01

66

The growth of structure in the intergalactic medium  

NASA Astrophysics Data System (ADS)

A `stochastic adhesion' model is introduced, with the purpose of describing the formation and evolution of mildly non-linear structures, such as sheets and filaments, in the intergalactic medium (IGM), after hydrogen reionization. The model is based on replacing the overall force acting on the baryon fluid - which results from the combination of local gravity, pressure gradients and Hubble drag - by a mock external force, self-consistently calculated from first-order perturbation theory. A small kinematic viscosity term prevents shell-crossing on small scales (which arises because of the approximate treatment of pressure gradients). The emerging scheme is an extension of the well-known adhesion approximation for the dark matter dynamics, from which it differs only by the presence of a small-scale `random' force, characterizing the IGM. Our algorithm is the ideal tool to obtain the skeleton of the IGM distribution, which is responsible for the structure observed in the low column density Ly? forest in the absorption spectra of distant quasars.

Matarrese, Sabino; Mohayaee, Roya

2002-01-01

67

Expected properties of the two-point autocorrelation function of the intergalactic medium  

NASA Astrophysics Data System (ADS)

Recent analyses of the fluctuations of the soft diffuse X-ray background (DXB) have provided indirect detection of a component consistent with the elusive warm-hot intergalactic medium (WHIM). In this work we use theoretical predictions obtained from hydrodynamical simulations to investigate the angular correlation properties of the WHIM in emission and assess the possibility of indirect detection with next-generation X-ray missions. Our results indicate that the angular correlation signal of the WHIM is generally weak but dominates the angular correlation function of the DXB outside virialized regions. Its indirect detection is possible but requires rather long exposure times [0.1-1] Ms, large (˜1°× 1°) fields of view and accurate subtraction of isotropic fore/background contributions, mostly contributed by Galactic emission. The angular correlation function of the WHIM, which turns out to be positive for ? < 5 arcmin, provides limited information on its spatial distribution. A satisfactory characterization of the WHIM in 3D can be obtained through spatially resolved spectroscopy. 1 Ms long exposures with next generation detectors will allow to detect ˜400 O VII+O VIII X-ray emission systems that could be used to trace the spatial distribution of the WHIM. We predict that these observations will allow us to estimate the WHIM correlation function with high statistical significance out to ˜10 Mpc h-1 and characterize its dynamical state through the analysis of redshift-space distortions. The detectable WHIM, which is typically associated with the outskirts of virialized regions rather than the filaments, has a non-zero correlation function with slope ?=-1.7 ± 0.1 and correlation length r0= 4.0 ± 0.1 Mpc h-1 in the range r= [4.5, 12] Mpc h-1. Redshift-space distances can be measured to assess the dynamical properties of the gas that we predict to be typically infalling on to large virialized structures.

Ursino, E.; Branchini, E.; Galeazzi, M.; Marulli, F.; Moscardini, L.; Piro, L.; Roncarelli, M.; Takei, Y.

2011-07-01

68

THEIA: Telescope for Habitable Exoplanets and Interstellar/Intergalactic Astronomy  

NASA Astrophysics Data System (ADS)

By combining an occultor with a 4-meter optical/ultraviolet telescope, THEIA (Telescope for Habiatable Earths and Interstellar/Intergalactic Astronomy) will conduct an observational program that address many of the most exciting questions in astrophysics. The telescope is an on-axis telescope with a MgF-coated primary and a LiF-coated secondary. This hybrid approach allows reasonable through-put in the UV without the need to coat a large piimary with LiF. The coronagraph/occultor system is also a hybrid that aims to reduce the requirements on each approach. The telescope feeds a rich instrument complement. The eXtrasolar Planet Characterizer (XPC) baseline instruments are three narrow-field cameras for the UV (0.25-4.0 microns), blue (0.4-0.7 microns) and red (0.7-1.0 microns) with filters, and an integral field spectrograph (IFS) operating in the red. A wide-field high-resolution camera (Star Formation Camera) operating with a blue (190--517nm) and a red (517--1075nm) channel will conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and their planetary systems. A UV high-resolution spectrograph (UVS) with R=30,000-100,000 in the far-UV (1000-1700 A) and near-UV (1700-3000 A) will strengthen the foundations of observational cosmology by examining the cosmic web (IGM), its interactions with galaxies, and its enrichment with the products of stellar and galactic evolution. This mission has two basic opseration modes. While the occultor is moving from target star to target star, the telescope carries out an exciting program of general astrophysics. While the occultor is on target, it will characterize the key properties of a detected planet and deeply image adjacent fields in parallel mode.

Spergel, David N.; Kasdin, J.; Belikov, R.; Atcheson, P.; Beasley, M.; Calzetti, D.; Cameron, B.; Copi, C.; Desch, S.; Dressler, A.; Ebbets, D.; Egerman, R.; Fullerton, A.; Gallagher, J.; Green, J.; Guyon, O.; Heap, S.; Jansen, R.; Jenkins, E.; Kasting, J.; Keski-Kuha, R.; Kuchner, M.; Lee, R.; Lindler, D.; Linfield, R.; Lisman, D.; Lyon, R.; Malhotra, S.; Mathews, G.; McCaughrean, M.; Mentzel, J.; Mountain, M.; NIkzad, S.; O'Connell, R.; Oey, S.; Padgett, D.; Parvin, B.; Procashka, J.; Reeve, W.; Reid, I. N.; Rhoads, J.; Roberge, A.; Saif, B.; Scowen, P.; Seager, S.; Seigmund, O.; Sembach, K.; Shaklan, S.; Shull, M.; Soummer, R.

2009-01-01

69

Temporal Smearing of Transient Radio Sources by the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

The temporal smearing of impulsive radio events at cosmological redshifts probes the properties of the ionized intergalactic medium (IGM). We relate the degree of temporal smearing and the profile of a scattered source to the evolution of a turbulent structure in the IGM as a function of redshift. We estimate the degree of scattering expected by analyzing the contributions to the scattering measure of the various components of baryonic matter embedded in the IGM, including the diffuse IGM, intervening galaxies, and intracluster gas. These estimates predict that the amount of temporal smearing expected at 300 MHz is typically as low as ~1 ms and suggests that these bursts may be detectable with low-frequency widefield arrays. A generalization of the dispersion-measure-scattering-measure relation observed for Galactic scattering to the densities and turbulent conditions relevant to the IGM suggests that scattering measures on the order of 10–6 kpc m–20/3 would be expected at z ~ 1. This scattering is sufficiently low enough that its effects would not, for most lines of sight, be manifested in existing observations of the scatter broadening in images of extragalactic compact sources. The redshift dependence on the temporal smearing discriminates between scattering that occurs in the host galaxy of the burst and the IGM, with ?hostvprop(1 + z)–3 if the scattering probes length scales below the inner scale of the turbulence or ?hostvprop(1 + z)–17/5 if the turbulence follows a Kolmogorov spectrum. This differs strongly from the expected IGM scaling ?IGM ~ z 2 for z <~ 1 and (1 + z)0.2 – 0.5 for z >~ 1.

Macquart, Jean-Pierre; Koay, Jun Yi

2013-10-01

70

Intergalactic mergers and starbursts and their role in galaxy evolution  

NASA Astrophysics Data System (ADS)

We present results from several research projects designed to explore star formation in galaxies and to better define the role that intense star formation and intergalactic mergers play in driving galaxy evolution. In Chapter 2 we examine the star formation histories of 1,200 galaxies in the local universe to determine the age of their stellar populations. We find a factor of approximately five increase in the amount of star formation from [Special characters omitted.] to [Special characters omitted.] . In Chapter 3 we explore the star forming properties of Extremely Red Objects (EROs) and find them to be significant sources of submillimeter emission, indicating the presence of dust-enshrouded star formation. We also find that these systems constitute a significant fraction (up to 61%) of the extragalactic background light in the submillimeter. In Chapters 4, 5, and 6, we examine starburst galaxies in the local ( z < 3, 000 km/s) universe. We discovered a closed tidal loop surrounding the starburst galaxy, NGC 3310. We find an upper limit of the HI gas in the loop to be on the order of [Special characters omitted.] , and we estimate its stellar mass content to be ~4 x 10 8 [Special characters omitted.] . We also find that the shell-like stellar debris surrounding this system is not consistent with having originated in NGC 3310's own disk, supporting the idea that this system was created during the collision of two equal mass, gas rich galaxies. We find that the surface brightness profile for this galaxy follows the R 1/4 law; however the Ha emission indicates the presence of a young, rotating disk. While this system has recently undergone a major collision, it appears to be in the process of forming a new stellar disk.

Wehner, Elizabeth Marie

71

Gamma-ray induced cascades and magnetic fields in the intergalactic medium  

SciTech Connect

We present the results of Monte Carlo simulations of three-dimensional electromagnetic cascade initiated by interactions of the multi-TeV {gamma} rays with the cosmological infrared/optical photon background in the intergalactic medium. Secondary electrons in the cascade are deflected by the intergalactic magnetic fields before they scatter on CMB photons. This leads to extended 0.1 deg. -10 deg. scale emission at multi-GeV and TeV energies around extragalactic sources of very high-energy {gamma} rays. The morphology of the extended emission depends, in general, on the properties of magnetic fields in the intergalactic medium. Using Monte Carlo simulated data sets, we demonstrate that the decrease of the size of extended source with the increase of energy allows to measure weak magnetic fields with magnitudes in the range from {<=}10{sup -16} G to 10{sup -12} G if they exist in the voids of the large scale structure.

Elyiv, A.; Neronov, A.; Semikoz, D. V. [Main Astronomical Observatory National Academy of Sciences of Ukraine, 27 Akademika Zabolotnoho Street 03680 Kyiv (Ukraine); ISDC Data Center for Astrophysics, Chemin d'Ecogia 16, 1290 Versoix (Switzerland) and Geneva Observatory, 51 Chemin des Maillettes, CH-1290 Sauverny (Switzerland); APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France) and Institute for Nuclear Research RAS, 60th October Anniversary Prospect 7a, Moscow, 117312 (Russian Federation)

2009-07-15

72

BROAD H I ABSORBERS AS METALLICITY-INDEPENDENT TRACERS OF THE WARM-HOT INTERGALACTIC MEDIUM  

SciTech Connect

Thermally broadened Lyalpha absorbers (BLAs) offer an alternative method to highly ionized metal lines for tracing the warm-hot intergalactic medium (WHIM) at T>10{sup 5} 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 Lyalpha 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 (dN/dz){sub 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{sub H{sub 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 OMEGA{sub BLA} = 6.3{sup +1.1}{sub -0.8} x 10{sup -3} h {sup -1}{sub 70} based on 10{sup 4} 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 OMEGA{sub BLA} = 3.6 x 10{sup -3} h {sup -1}{sub 70} or 9.1 x 10{sup -3} h {sup -1}{sub 70}, depending on which assumptions were made about hydrogen neutral fraction. Taking our value, current O VI and BLA surveys can account for {approx} 20% of the baryons in the local universe while an additional {approx} 29% can be accounted for in the photoionized Lyalpha 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.

Danforth, Charles W.; Stocke, John T.; Shull, J. Michael, E-mail: danforth@casa.colorado.ed, E-mail: john.stocke@colorado.ed, E-mail: michael.shull@colorado.ed [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States)

2010-02-10

73

The Temperature-Density Relation in the Intergalactic Medium at Redshift langzrang = 2.4  

NASA Astrophysics Data System (ADS)

We present new measurements of the temperature-density (T-?) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of ~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 H I ) and the minimum observed velocity width of absorbers (b min). With minimal interpretation, this implies that the T-? relation in the IGM is not "inverted," contrary to many recent studies. Fitting b min as a function of N H I results in line-width-column-density dependence of the form b min = b 0(N H I /N H I,0)?-1 with a minimum line width at mean density (\\rho /\\bar{\\rho }= 1, N_H\\,\\mathsc{i, 0} = 10^{13.6} cm-2) of b 0 = 17.9 ± 0.2 km s-1 and a power-law index of (? - 1) = 0.15 ± 0.02. Using analytic arguments, these measurements imply an "equation of state" for the IGM at langzrang = 2.4 of the form T=T_0 \\left(\\rho /\\bar{\\rho }\\right)^{\\gamma -1} with a temperature at mean density of T 0 = [1.94 ± 0.05] × 104 K and a power-law index (? - 1) = 0.46 ± 0.05. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation.

Rudie, Gwen C.; Steidel, Charles C.; Pettini, Max

2012-10-01

74

Multiple Absorption-line Spectroscopy of the Intergalactic Medium. I. Model  

NASA Astrophysics Data System (ADS)

We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat & Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z ~ 0.1877 along the 1ES 1553+113 sight line. We identify Ly?, C III, O VI, and N V absorption lines with two distinct velocity components (blue at zb = 0.18757; red at zr = 0.18772) separated by ?(cz)/(1 + z) ? 38 km s-1. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 × 105 K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n H = (1.9-2.3) × 10-5 cm-3 and Z = (0.43-0.67) Z sun. These constraints indicate O VI and H I ionization fractions, f O VI = 0.10-0.15 and f H I = (3.2-5.1) × 10-5, with total hydrogen column density N H = (0.7-1.2) × 1018 cm-2. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

Yao, Yangsen; Shull, J. Michael; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T.

2011-04-01

75

Recovering the topology of the intergalactic medium at z ~ 2  

NASA Astrophysics Data System (ADS)

We investigate how well the three-dimensional density field of neutral hydrogen in the intergalactic medium (IGM) can be reconstructed using the Lyman ? absorptions observed along lines-of-sight to quasars separated by arcmin distances in projection on the sky. We use cosmological hydrodynamical simulations to compare the topologies of different fields: dark matter, gas and neutral hydrogen optical depth and to investigate how well the topology of the IGM can be recovered from the Wiener interpolation method implemented by Pichon et al. The global statistical and topological properties of the recovered field are analysed quantitatively through the power spectrum, the probability distribution function (PDF), the Euler characteristics, its associated critical point counts and the filling factor of underdense regions. The local geometrical properties of the field are analysed using the local skeleton by defining the concept of interskeleton distance. As a consequence of the nearly lognormal nature of the density distribution at the scales under consideration, the tomography is best carried out on the logarithm of the density rather than the density itself. At scales larger than ~1.4 , where is the mean separation between lines-of-sight, the reconstruction accurately recovers the topological features of the large-scale density distribution of the gas, in particular the filamentary structures: the interskeleton distance between the reconstruction and the exact solution is smaller than . At scales larger than the intrinsic smoothing length of the inversion procedure, the power spectrum of the recovered HI density field matches well that of the original one and the low-order moments of the PDF are well recovered as well as the shape of the Euler characteristic. The integral errors on the PDF and the critical point counts are indeed small, less than 20 per cent for a mean line-of-sight separation smaller than ~2.5 arcmin. The small deviations between the reconstruction and the exact solution mainly reflect departures from the lognormal behaviour that are ascribed to highly non-linear objects in overdense regions.

Caucci, S.; Colombi, S.; Pichon, C.; Rollinde, E.; Petitjean, P.; Sousbie, T.

2008-05-01

76

The angular deviation of ultra high energy cosmic rays in intergalactic magnetic fields  

Microsoft Academic Search

The angular deviation associated with the propagation of ultra high energy cosmic ray protons through turbulent intergalactic magnetic fields is examined including the effect of interactions with the cosmic microwave background. It is found that the deviation of the particles is consistent with diffusion ideas but the magnitude of the deviation is appreciably less than suggested by simple models for

R. W. Clay; S. Cook; B. R. Dawson; A. G. K. Smith; R. Lampard

1998-01-01

77

A numerical model of resistive generation of intergalactic magnetic field at cosmic dawn  

Microsoft Academic Search

Miniati and Bell (2011) proposed a mechanism for the generation of magnetic seeds that is based the finite resistivity of the low temperature IGM in the high redshift universe. In this model, cosmic-ray protons generated by the first generation of galaxies, escape into the intergalactic medium carrying an electric current that induces return currents, $j_t$, and associated electric fields, $\\\\vec

Francesco Miniati; A. R. Bell

2011-01-01

78

Large scale structure in the intergalactic magnetic field and ultra-high energy cosmic ray propagation  

Microsoft Academic Search

The possibility that the magnetic field is strongly correlated with the large-scale structure of the universe has been recently proposed in the literature. In this scenario the intergalactic magnetic field has a strong (m Gauss) regular component spanning tens of Mpc. This could have severe consequences on the propagation of ultra-high energy cosmic rays, and the observed spectra, isotropy and

Gustavo Medina Tanco

1998-01-01

79

Photon-Axion Conversion in Intergalactic Magnetic Fields and Cosmological Consequences  

Microsoft Academic Search

Photon-axion conversion induced by intergalactic magnetic fields causes an apparent dimming of distant sources, notably of cosmic distance indicators such as supernovae of type Ia (SNe Ia). We review the impact of this mechanism on the luminosity-redshift relation of SNe Ia, on the dispersion of quasar spectra, and on the spectrum of the cosmic microwave background. The original idea of

Alessandro Mirizzi; Georg G. Raffelt; Pasquale D. Serpico

2008-01-01

80

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

Microsoft Academic Search

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

Takuya Akahori; Dongsu Ryu

2011-01-01

81

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

82

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

SciTech Connect

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

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

2009-05-15

83

MULTIPLE ABSORPTION-LINE SPECTROSCOPY OF THE INTERGALACTIC MEDIUM. I. MODEL  

SciTech Connect

We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat and Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z {approx} 0.1877 along the 1ES 1553+113 sight line. We identify Ly{alpha}, C III, O VI, and N V absorption lines with two distinct velocity components (blue at z{sub b} = 0.18757; red at z{sub r} = 0.18772) separated by {Delta}(cz)/(1 + z) {approx} 38 km s{sup -1}. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 x 10{sup 5} K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n{sub H} = (1.9-2.3) x 10{sup -5} cm{sup -3} and Z = (0.43-0.67) Z{sub sun}. These constraints indicate O VI and H I ionization fractions, f{sub OVI} = 0.10-0.15 and f{sub HI} = (3.2-5.1) x 10{sup -5}, with total hydrogen column density N{sub H} = (0.7-1.2) x 10{sup 18} cm{sup -2}. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

Yao Yangsen; Michael Shull, J.; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T., E-mail: yaoys@colorado.edu [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States)

2011-04-01

84

Intergalactic spaceflight: an uncommon way to relativistic kinematics and dynamics  

Microsoft Academic Search

In the Special Theory of Relativity space and time intervals are different in different frames of reference. As a consequence, the quantity 'velocity' of classical mechanics splits into different quantities in Special Relativity, coordinate velocity, proper velocity and rapidity. The introduction and clear distinction of these quantities provides a basis to introduce the kinematics of uniform and accelerated motion in

Thomas Greber; Heinz Blatter

2006-01-01

85

Simulating the Chemical Enrichment of the Intergalactic Medium  

Microsoft Academic Search

Over the past few decades, it has become evident that the vast amount of space that exists between galaxies contains trace amounts of elements heavier than helium ('metals' in astronomical terms). This is surprising since the baryonic universe is expected to initially be composed of solely hydrogen, helium and very small amounts of lithium and beryllium. Metals are predicted to

Robert Peter Coalter Wiersma

2010-01-01

86

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

SciTech Connect

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. 38 references.

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

1986-05-01

87

Detecting intergalactic magnetic fields using time delays in pulses of gamma-rays  

Microsoft Academic Search

INTERGALACTIC magnetic fields (IGMFs) can be produced by a number of mechanisms, but are expected to be weak and have not so far been detected. 'Primordial' magnetic fields might have been produced in the very early Universe, either by quantum fluctuations during the 'inflationary' period1,2 or through the decoupling transitions of the fundamental forces3,4. The much later ejection of magnetized

R. Plaga

1995-01-01

88

Photon-Axion Conversion in Intergalactic Magnetic Fields and Cosmological Consequences  

Microsoft Academic Search

Photon-axion conversion induced by intergalactic magnetic fields causes an apparent dimming of distant sources, notably of\\u000a cosmic distance indicators such as supernovae of type Ia (SNe Ia). We review the impact of this mechanism on the luminosity-redshift\\u000a relation of SNe Ia, on the dispersion of quasar spectra, and on the spectrum of the cosmic microwave background. The original\\u000a idea of

Alessandro Mirizzi; Georg G. Raffelt; Pasquale D. Serpico

89

Constraints on the intergalactic magnetic field from gamma-ray observations of TeV blazars  

Microsoft Academic Search

We discuss different approaches to infer the properties of the intergalactic magnetic field (IGMF) from gamma-ray observations of blazars. In particular, we investigate constraints on the IGMF strength and spacial distribution, resulting from studies of TeV blazars by imaging atmospheric Cherenkov telescopes and the Fermi-LAT instrument. We demonstrate that the non-observation of GeV gamma-rays from powerful TeV blazars indicates that

M Kachelrieß; S Ostapchenko; R Tomàs

2012-01-01

90

Gamma-ray halos as a measure of intergalactic magnetic fields: A classical moment problem  

Microsoft Academic Search

The presence of weak intergalactic magnetic fields can be studied by their effect on electromagnetic cascades induced by multi-TeV gamma rays in the cosmic radiation background. Small deflections of secondary electrons and positrons as the cascade develops extend the apparent size of the emission region of distant TeV gamma-ray sources. These gamma-ray halos can be resolvable in imaging atmospheric Cherenkov

Markus Ahlers

2011-01-01

91

Large scale structure in the intergalactic magnetic field and ultra-high energy cosmic ray propagation  

Microsoft Academic Search

The possibility that the magnetic field is strongly correlated with the\\u000alarge-scale structure of the universe has been recently proposed in the\\u000aliterature. In this scenario the intergalactic magnetic field has a strong (m\\u000aGauss) regular component spanning tens of Mpc. This could have severe\\u000aconsequences on the propagation of ultra-high energy cosmic rays, and the\\u000aobserved spectra, isotropy and

Gustavo Medina Tanco

1998-01-01

92

Constraining the intergalactic magnetic field with cascading TeV emission from cosmological GRBs  

Microsoft Academic Search

The high energy (> 100 GeV) emission of cosmological GRBs will be attenuated by photon-photon pair production on infrared and optical background light. The energy of these ``absorbed'' photons is reprocessed by cascading to lower energies. The reprocessing induces a delay in the arrival of cascade X-rays and results in a finite angular size for the source. If an intergalactic

Bruce Roscherr; Paolo S. Coppi

1998-01-01

93

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

Microsoft Academic Search

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

Dongsu Ryu; Santabrata Das; Hyesung Kang

2010-01-01

94

New Probes of Intergalactic Magnetic Fields by Radiometry and Faraday Rotation  

Microsoft Academic Search

The energy injection of galactic black holes (BH) into the intergalactic medium via extragalactic radio source jets and lobes is sufficient to magnetize the IGM in the filaments and walls of Large Scale Structure at ˜ 0.1muG or more. It appears that this process of galaxy-IGM feedback is the primary source of IGM cosmic rays(CR) and magnetic field energy. Large

Philipp P. Kronberg

2004-01-01

95

Detectability of Pair Echoes from Gamma-Ray Bursts and Intergalactic Magnetic Fields  

Microsoft Academic Search

High-energy emission from gamma-ray bursts (GRBs) can give rise to pair echoes, i.e., delayed inverse Compton emission from secondary electron-positron pairs produced in photon-photon interactions with intergalactic background radiation. We investigate the detectability of such emission with modern-day gamma-ray telescopes. The spectra and light curves are calculated for a wide range of parameters, applying the formalism recently developed by Ichiki

Keitaro Takahashi; Kohta Murase; Kiyotomo Ichiki; Susumu Inoue; Shigehiro Nagataki

2008-01-01

96

Gamma-Ray Burst Afterglows as Probes of Galactic and Intergalactic Dust  

Microsoft Academic Search

The amount and properties of high-redshift galactic and intergalactic (IG) dust are largely unknown but could be investigated using multiwavelength photometry of high-z objects that have a known intrinsic spectrum. Observations of gamma-ray burst (GRB) afterglows appear to support the theoretical model of an adiabatic blast wave expanding into an external medium. In this model the synchrotron peak flux is

Rosalba Perna; Anthony Aguirre

2000-01-01

97

Low Surface Brightness H alpha Observations of Local Intergalactic Hydrogen Clouds  

Microsoft Academic Search

We present upper limits on the local ionizing background based on a search for extended H alpha emission from three nearby intergalactic H I clouds: the Leo Ring (M96 group), both the NE and SW lobes of the Haynes-Giovanelli Virgo Cloud (H I 1225+01), and the H I tidal tails associated with the NGC 4631\\/4656 group. These clouds were chosen

Megan Donahue; Greg Aldering; John T. Stocke

1995-01-01

98

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

99

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

100

INTERGALACTIC GAS IN GROUPS OF GALAXIES: IMPLICATIONS FOR DWARF SPHEROIDAL FORMATION AND THE MISSING BARYONS PROBLEM  

SciTech Connect

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{sup -3} to 10{sup -4} cm{sup -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 10{sup 6}-10{sup 7} M{sub 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. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Wilcots, E., E-mail: freeland@physics.tamu.edu, E-mail: ewilcots@astro.wisc.edu [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)

2011-09-10

101

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

102

The Low-redshift Intergalactic Medium as Seen in Archival Legacy HST/STIS and FUSE Data  

NASA Astrophysics Data System (ADS)

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 mÅ over a maximum redshift path length ?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, \\left(\\partial ^2 {N}/\\partial z\\partial N\\right) \\propto N^{-\\beta }, where ? = 2.08 ± 0.12 for O VI and ? = 1.68 ± 0.03 for H I. Utilizing a more sophisticated accounting technique than past work, our catalog accounts for ~43% of the baryons: 24% ± 2% in the photoionized Ly? 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. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Tilton, Evan M.; Danforth, Charles W.; Shull, J. Michael; Ross, Teresa L.

2012-11-01

103

Consequences of Starbursts for the Interstellar and Intergalactic Medium  

NASA Astrophysics Data System (ADS)

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

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

104

Detectability of Pair Echos from Gamma-Ray Bursts and Intergalactic Magnetic Fields  

Microsoft Academic Search

High-energy emission from gamma-ray bursts (GRBs) can give rise to pair\\u000aechos, i.e. delayed inverse Compton emission from secondary $e^{\\\\pm}$ pairs\\u000aproduced in $\\\\gamma-\\\\gamma$ interactions with intergalactic background\\u000aradiation. We investigate the detectability of such emission with modern-day\\u000agamma-ray telescopes. The spectra and light curves are calculated for a wide\\u000arange of parameters, applying the formalism recently developed by Ichiki

Keitaro Takahashi; Kohta Murase; Kiyotomo Ichiki; Susumu Inoue; Shigehiro Nagataki

2008-01-01

105

The First Science Flight of the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL)  

NASA Astrophysics Data System (ADS)

We have completed the second flight of the path-finding experiment, the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL), designed to discover and map faint emis-sion from the Intergalactic Medium (IGM). The second flight was fully successful, proving a fully functional fine pointing gondola with arcsec level capability, a 1 meter diameter (fixed) parabola primary telescope with planar sidereostat for pointing, a complete closed loop guide camera and control software, and a fiber fed UV integral field spectrograph feeding a spare GALEX Near UV detector. Three scientific targets were observed, and analysis of the data shows that the instrument performed as expected. The flux measurements obtained will be compared to models for IGM emission. We discuss future modifications to the payload that will achieve a 10-to 30-fold increase in sensitivity over science flight 1. We also discuss other instrument configurations that can utilize the 1-meter UV telescope and arcsecond pointing platform, and their corresponding science objectives. FIREBALL is a collaboration of NASA, Caltech, Columbia University, CNES, and Laboratorie Astrophysique Marseille, and is sup-ported by NASA, CNES, and CNRS.

Martin, Christopher; Milliard, Bruno; Schiminovich, David; Tuttle, Sarah; Matuszewski, Matt; Rahman, Shahin; Evrard, Jean; Frank, Stephan; Deharveng, Jean-Michel; Peroux, Celine

106

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

PubMed

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

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

2013-10-31

107

Release of protons with energy >10 18 eV from intergalactic magnetic field into interstellar magnetic field  

Microsoft Academic Search

Drift instabilities arising when accelerated protons are trapped in the intergalactic medium are examined. If a, the ratio of total (plasma + energetic particles) pressure and magnetic field pressure is larger than some value a?0.1 to 0.3, the magnetic trap is destroyed and protons are released into interstellar medium. If a*, the trapped protons exhibit gradient instability due to magnetic

Ajoy K. Dasgupta

1983-01-01

108

Polarization of Absorption Lines as a Diagnostics of Circumstellar, Interstellar, and Intergalactic Magnetic Fields: Fine-Structure Atoms  

Microsoft Academic Search

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

Huirong Yan; A. Lazarian

2006-01-01

109

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

NASA Astrophysics Data System (ADS)

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

Huan, Hao

2012-05-01

110

Constraining the intergalactic magnetic field with cascading TeV emission from cosmological GRBs  

NASA Astrophysics Data System (ADS)

The high energy (> 100 GeV) emission of cosmological GRBs will be attenuated by photon-photon pair production on infrared and optical background light. The energy of these ``absorbed'' photons is reprocessed by cascading to lower energies. The reprocessing induces a delay in the arrival of cascade X-rays and results in a finite angular size for the source. If an intergalactic magnetic field is present then the X-ray flux as a function of both time and angle from the source change in a way that is characteristic of the field strength. We here calculate the cascade X-ray flux expected from a bright GRB and show that fields as low as 10-22 G have a discernable effect on the flux. The flux level, however, is too low to currently be detected, but a similar analysis might be more fruitfully applied to blazar AGNs.

Roscherr, Bruce; Coppi, Paolo S.

1998-05-01

111

Possibility of measuring the amount of intergalactic metals with 14N VII HFS line  

NASA Astrophysics Data System (ADS)

We discuss possibility of observations of the warm-hot intergalactic medium using the hyperfine structure line of highly charged nitrogen ion 14N VII (rest wavelength ? = 5.652 mm). Observations of this line will allow to separate bulk and turbulent motions in the observed target and will broaden the information about the gas ionization state, chemical and isotopic composition. Wavelength of this line is well-suited for ground-based observation of objects at z ? 0.15 - 0.6 when it is redshifted to the widely-used 6.5 - 9 mm spectral band, and, for example, for z ? 1.3, when the line can be observed in 1.3 cm band and at lower frequencies.

Docenko, Dmitrijs; Sunyaev, Rashid A.

2010-03-01

112

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

113

Correlation Between X-ray And Microwave (sz) Signals From The Warm-hot Intergalactic Medium  

NASA Astrophysics Data System (ADS)

A large fraction of the low redshift baryons is believed to reside in a warm-hot filamentary gas in the intergalactic medium (WHIM). In the past we have successfully used XMM-Newton data to identify and characterize the WHIM angular signature using the autocorrelation function [Galeazzi 2009, 695, 1127]. Using the output of large scale hydrodynamic simulations we have also investigated the correlation between low energy X-ray emission and SZ effect from WHIM filaments. The largest of the current SZ surveys (with the South Pole Telescope [Ruhl 2004, Proc. SPIE, 5498, 11] and the Atacama Cosmology Telescope [Kosowsky 2004, NAR 47, 939; 2006, NAR 50, 969]) are mapping hundreds of square degrees at arcminute resolution at bands in 100-300 GHz, and have started identifying clusters detected by their SZ signature alone [e.g. Staniszewski 2009, ApJ, 701,32; Hincks 2009, arXiv:0907.0461]. Although the bulk of the total luminosity in the SZ effect is associated with collapsed structures like clusters, our work indicates that a significant fraction comes from unbound objects, mostly from overdense regions, like the WHIM. Due to the unique emission mechanism, the X-ray and SZ correlation provides additional constraints on the structure of the intergalactic gas. Adopting an adiabatic, polytropic model the SZ signal goes as ne1.2, compared with the x-ray emission that goes roughly as ne2 (slightly modified by the cooling function). In this paper we will discuss the result of our investigation on the correlation between X-ray emission and SZ signals and the implications for current X-ray and SZ observatories. We will also present our preliminary applications using actual data.

Galeazzi, Massimiliano; Gupta, A.; Huffenberger, K.; Ursino, E.

2010-05-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

115

Time Delay of Cascade Radiation for TeV Blazars and the Measurement of the Intergalactic Magnetic Field  

Microsoft Academic Search

Recent claims that the strength B IGMF of the intergalactic magnetic field (IGMF) is >~ 10-15 G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background light. This limit depends on an assumption that the mean blazar TeV flux remains constant on timescales >~ 2(B

Charles D. Dermer; Massimo Cavadini; Soebur Razzaque; Justin D. Finke; James Chiang; Benoit Lott

2011-01-01

116

Probing the Nature of the Weakest Intergalactic Magnetic Fields with the High-Energy Emission of Gamma-Ray Bursts  

Microsoft Academic Search

We investigate the delayed, secondary GeV-TeV emission of gamma-ray bursts and its potential to probe the nature of intergalactic magnetic fields. Geometrical effects are properly taken into account for the time delay between primary high-energy photons and secondary inverse Compton photons from electron-positron pairs, which are produced in gamma-gamma interactions with background radiation fields and deflected by intervening magnetic fields.

Kiyotomo Ichiki; Susumu Inoue; Keitaro Takahashi

2008-01-01

117

A study of the intergalactic magnetic field using extragalactic ultra-high-energy gamma-ray sources  

Microsoft Academic Search

The possibility of measuring the intergalactic magnetic field between an extragalactic ultrahigh-energy (UHE) gamma-ray source and the Galaxy is considered. It is found that, if there is a strong UHE gamma-ray source at a distance of less than about 100 kpc, the magnetic field between the Galaxy and the source can be studied by UHE gamma-ray observations. If the field

M. Honda

1989-01-01

118

Evidence for Gamma-ray Halos Around Active Galactic Nuclei and the First Measurement of Intergalactic Magnetic Fields  

Microsoft Academic Search

Intergalactic magnetic fields (IGMFs) can cause the appearance of halos around the gamma-ray images of distant objects because an electromagnetic cascade initiated by a high-energy gamma-ray interaction with the photon background is broadened by magnetic deflections. We report evidence of such gamma-ray halos in the stacked images of the 170 brightest active galactic nuclei (AGNs) in the 11 month source

Shin'ichiro Ando; Alexander Kusenko

2010-01-01

119

Observations of intergalactic heavy-element enrichment in the early universe  

NASA Astrophysics Data System (ADS)

We present the results of a search for O VI absorption in the intergalactic medium (IGM) at 2 [Special characters omitted.] z [Special characters omitted.] 3. The measurements are taken from a set of 7 quasars observed with Keck I/ HIRES. We find two classes of O VI system in the high redshift IGM. The first class is more rare (2-4 per sightline) and also quite strong ( N H I >= 10 15.2 ). These systems resemble hot, collisionally ionized gas at high densities, and contain complex mixtures of H I and metals at a range of temperatures. Although we cannot measure the metallicities of individual strong absorbers, we estimate that the total population is enriched over 10 times above the level of the general IGM. We propose that the strong systems represent either accretion-shocked gas falling onto primitive large-scale structure, or (more likely) the remnants of high redshift galactic winds mixing into the IGM. The second class of O VI absorber is much weaker, arising in low-density gas that is photoionized by metagalactic UV/X-ray radiation. We measure the metal content of these systems, down to densities of r/ r [Special characters omitted.] 1.6 relative to the cosmic mean. This corresponds to the filaments of the cosmic web, which contain over half of the baryons in the high redshift universe. We develop a new method to calculate the metallicity distribution function of the Ly-a forest using survival statistics. Carbon and oxygen are both distributed lognormally, with mean [left angle bracket][ O/H ][right angle bracket] [approximate] -2.85 and scatter of s = 0.75 dex. We observe no decline in metallicity toward lower densities, indicating that metals are mixed very efficiently within the filaments. Comparison with Population III and galactic wind enrichment models suggests that the enrichment was dominated by superwinds. We estimate that roughly half of all baryons in the IGM came into contact with metal-rich winds by z ~ 2.5. Using a "closed box" model of intergalactic enrichment, we estimate that early galaxies typically recycled 0.1-0.4% of their mass back into the IGM as heavy elements prior to this epoch.

Simcoe, Robert Andrew

2004-12-01

120

The enrichment of the intergalactic medium with adiabatic feedback - I. Metal cooling and metal diffusion  

NASA Astrophysics Data System (ADS)

A study of metal enrichment of the intergalactic medium (IGM) using a series of smooth particle hydrodynamic (SPH) simulations is presented, employing models for metal cooling and the turbulent diffusion of metals and thermal energy. An adiabatic feedback mechanism was adopted where gas cooling was prevented on the time-scale of supernova bubble expansion to generate galactic winds without explicit wind particles. The simulations produced a cosmic star formation history (SFH) that is broadly consistent with observations until z ~ 0.5, and a steady evolution of the universal neutral hydrogen fraction () that compares reasonably well with observations. The evolution of the mass and metallicities in stars and various gas phases was investigated. At z = 0, about 40 per cent of the baryons are in the warm-hot intergalactic medium (WHIM), but most metals (80-90 per cent) are locked in stars. At higher redshifts the proportion of metals in the IGM is higher due to more efficient loss from galaxies. The results also indicate that IGM metals primarily reside in the WHIM throughout cosmic history, which differs from simulations with hydrodynamically decoupled explicit winds. The metallicity of the WHIM lies between 0.01 and 0.1 solar with a slight decrease at lower redshifts. The metallicity evolution of the gas inside galaxies is broadly consistent with observations, but the diffuse IGM is under enriched at z ~ 2.5. Galactic winds most efficiently enrich the IGM for haloes in the intermediate mass range 1010-1011 Msolar. At the low-mass end gas is prevented from accreting on to haloes and has very low metallicities. At the high-mass end, the fraction of halo baryons escaped as winds declines along with the decline of stellar mass fraction of the galaxies. This is likely because of the decrease in star formation activity and decrease in wind escape efficiency. Metals enhance cooling which allows WHIM gas to cool on to galaxies and increases star formation. Metal diffusion allows winds to mix prior to escape, decreasing the IGM metal content in favour of gas within galactic haloes and star-forming gas. Diffusion significantly increases the amount of gas with low metallicities and changes the density-metallicity relation.

Shen, S.; Wadsley, J.; Stinson, G.

2010-09-01

121

EFFECT OF METALLICITY ON X-RAY EMISSION FROM THE WARM-HOT INTERGALACTIC MEDIUM  

SciTech Connect

Hydrodynamic simulations predict that a significant fraction of the gas in the current universe is in the form of high temperature, highly ionized plasma emitting and absorbing primarily in the soft X-ray and UV bands, dubbed the warm-hot intergalactic medium (WHIM). Its signature should be observable in redshifted emission and absorption lines from highly ionized elements. To determine the expected WHIM emission in the soft X-ray band we used the output of a large scale smoothed particle hydrodynamic simulation to generate images and spectra with angular resolution of 14'' and energy resolution of 1 eV. The current biggest limit of any hydrodynamic simulation in predicting the X-ray emission comes from metal diffusion. In our investigation, by using four different models for the WHIM metallicity we have found a strong dependence of the emission on the model used, with differences up to almost an order of magnitude. For each model, we have investigated the redshift distribution and angular scale of the emission, confirming that most photons come from redshift z < 1.2 and that the emission has a typical angular scale of less than a few arcminutes. We also compared our simulations with the few currently available observations and found that, within the variation of the metallicity models, our predictions are in good agreement with current constraints on the WHIM emission, and at this time the weak experimental constraints on the WHIM emission are not sufficient to exclude any of the models used.

Ursino, E.; Galeazzi, M. [Physics Department, University of Miami, Coral Gables, FL 33155 (United States); Roncarelli, M., E-mail: galeazzi@physics.miami.ed [Dipartimento di Astronomia, Universita di Bologna, via Ranzani 1, I-40127 Bologna (Italy)

2010-09-20

122

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

SciTech Connect

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

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

2011-09-10

123

Intergalactic Magnetic Field and Arrival Direction of Ultra-High-Energy Iron Nuclei  

NASA Astrophysics Data System (ADS)

We have studied how the intergalactic magnetic field (IGMF) affects the propagation of super-GZK iron nuclei 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 at high density region to represent astronomical objects formed in the large scale structure (LSS).With our model IGMF, the paths of UHE iron nuclei are deflected on average by about 70 degrees, which might indicate a nearly isotropic distribution of arrival directions. However, the separation angle between the arrival directions and the nearest reference object on the LSS is only 6 degrees, which is twice the mean distance to the nearest neighbors among the reference objects. This means that the positional correlation of observed UHE iron events with their true sources would be erased by the IGMF, but the correlation with the LSS itself is to be sustained. We discuss implications of our findings for correlations studies of real UHECR events.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0002433).

Kang, Hyesung; Das, S.; Ryu, D.

2012-05-01

124

The Signature of the Warm-Hot Intergalactic Medium in WMAP and the Forthcoming Planck Data  

NASA Astrophysics Data System (ADS)

We compute the cross-correlation between the Warm-Hot Intergalactic Medium and maps of cosmic microwave background temperature anisotropies using a log-normal probability density function to describe the weakly nonlinear matter density field. We search for this contribution in the data measured by the Wilkinson Microwave Anisotropy Probe. We use a template of projected matter density reconstructed from the Two-Micron All-Sky Redshift Survey as a tracer of the electron distribution. The spatial distribution of filaments is modeled using the recently developed Augmented Lagrangian Perturbation Theory. On the scales considered here, the reconstructed density field is very well described by the assumed log-normal distribution function. We predict that the cross-correlation will have an amplitude of 0.03-0.3 ?K. The measured value is close to 1.5 ?K, compatible with random alignments between structure in the template and in the temperature anisotropy data. Using the W1 Differencing Assembly to remove this systematic gives a residual correlation dominated by Galactic foregrounds. Planck could detect the Warm-Hot Medium if it is well traced by the density field reconstructed from galaxy surveys. The 217 GHz channel will allow to eliminate spurious contributions and its large frequency coverage can show the sign change from the Rayleigh-Jeans to the Wien part of the spectrum, characteristic of the thermal Sunyaev-Zel'dovich effect.

Suarez-Velásquez, I.; Kitaura, F.-S.; Atrio-Barandela, F.; Mücket, J. P.

2013-05-01

125

Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR  

NASA Astrophysics Data System (ADS)

We discuss the feasibility of the detection of the 21 cm forest in the diffuse intergalactic medium (IGM) with the radio telescope LOFAR. The optical depth to the 21 cm line has been derived using simulations of reionization which include detailed radiative transfer of ionizing photons. We find that the spectra from reionization models with similar total comoving hydrogen ionizing emissivity but different frequency distribution look remarkably similar. Thus, unless the reionization histories are very different from each other (e.g. a predominance of UV versus X-ray heating) we do not expect to distinguish them by means of observations of the 21 cm forest. Because the presence of a strong X-ray background would make the detection of the 21 cm line absorption impossible, the lack of absorption could be used as a probe of the presence/intensity of the X-ray background and the thermal history of the Universe. Along a random line of sight LOFAR could detect a global suppression of the spectrum from z ? 12, when the IGM is still mostly neutral and cold, in contrast with the more well-defined, albeit broad, absorption features visible at lower redshift. Sharp, strong absorption features associated with rare, high-density pockets of gas could also be detected at z ˜ 7 along preferential lines of sight.

Ciardi, B.; Labropoulos, P.; Maselli, A.; Thomas, R.; Zaroubi, S.; Graziani, L.; Bolton, J. S.; Bernardi, G.; Brentjens, M.; de Bruyn, A. G.; Daiboo, S.; Harker, G. J. A.; Jelic, V.; Kazemi, S.; Koopmans, L. V. E.; Martinez, O.; Mellema, G.; Offringa, A. R.; Pandey, V. N.; Schaye, J.; Veligatla, V.; Vedantham, H.; Yatawatta, S.

2013-01-01

126

Search for Oxygen Emission from Warm-Hot Intergalactic Medium around A2218 with Suzaku  

SciTech Connect

We searched for redshifted O emission lines from the possible warm-hot intergalactic medium (WHIM) surrounding the cluster of galaxies A2218 at z = 0.1756 using the XIS instrument on Suzaku. This cluster is thought to have an elongated structure along the line of sight based on previous studies. We studied systematic uncertainties in the spectrum of the Galactic emission and in the soft X-ray response of the detectors due to the contamination building up on the XIS filters. We detected no significant redshifted O lines, and set a tight constraint on the intensity with upper limits for the surface brightness of O{sub VII} and O{sub VIII} lines of 1.1 x 10{sup -7} and 3.0 x 10{sup -7} photons cm{sup -2} s{sup -1} arcmin{sup -2}, respectively. These upper limits are significantly lower than the previously reported fluxes from the WHIM around other clusters of galaxies. We also discuss the prospect for the detection of the WHIM lines with Suzaku XIS in the future.

Takei, Yoh; Ohashi, Takaya; Henry, J.Patrick; Mitsuda, Kazuhisa; Fujimoto, Ryuichi; Tamura, Takayuki; Yamasaki, Noriko Y.; Hayashida, Kiyoshi; Tawa, Noriaki; Matsushita, Kyoko; Bautz, Mark W.; Hughes, John P.; Madejski, Grzegorz M.; Kelley, Richard L.; Arnaud, Keith A.; /JAXA, Sagamihara /Tokyo Metropolitan U. /Inst. Astron., Honolulu /Osaka U. /Sci. U., Tokyo /MIT, MKI /Rutgers U., Piscataway /SLAC /NASA, Goddard

2006-09-08

127

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

NASA Astrophysics Data System (ADS)

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

Nagamine, Kentaro; Loeb, Abraham

2004-10-01

128

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

129

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

130

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

SciTech Connect

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

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

2010-12-10

131

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

SciTech Connect

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

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

2009-11-10

132

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

133

Probing Warm-Hot Intergalactic Medium Associated with the Virgo Cluster Using an Oxygen Absorption Line  

NASA Astrophysics Data System (ADS)

To detect a warm-hot intergalactic medium (WHIM) associated with the large-scale structure of the universe, we observed a quasar behind the Virgo cluster with XMM-Newton. With 54ks exposure, we marginally detected an O VIII K? absorption line at 650.9+0.8-1.9eV in the RGS spectra, with a statistical confidence of 96.4%. The observed line center energy is consistent with the redshift of M 87, and hence the absorber is associated with the Virgo cluster. From the curve of growth, the O VIII column density was estimated to be ? 7 × 1016 cm-2. In the EPIC spectra, excess emission was found after evaluating the hot ICM in the Virgo cluster and various background components. We inspected the RASS map of the diffuse soft X-ray background, and confirmed that the level of the north and west regions just outside of the Virgo cluster is consistent with the background model that we used, while that of the east side is significantly higher and the enhancement is comparable with the excess emission found in the EPIC data. We consider a significant portion of the excess emission to be associated with the Virgo cluster, although a possible contribution from the North Polar Spur cannot be excluded. Using the column density and the emission measure and assuming an oxygen abundance of 0.1 and an ionization fraction of 0.4, we estimate that the mean electron density and the line-of-sight distance of the warm-hot gas are ? 6 × 10-5 cm-3 and ? 9 Mpc. These strongly suggest detection of a WHIM in a filament associated with the Virgo cluster.

Fujimoto, Ryuichi; Takei, Yoh; Tamura, Takayuki; Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Shibata, Ryo; Ohashi, Takaya; Ota, Naomi; Audley, Michael D.; Kelley, Richard L.; Kilbourne, Caroline A.

2004-10-01

134

Turbulence in the Intergalactic Medium: Solenoidal and Dilatational Motions and the Impact of Numerical Viscosity  

NASA Astrophysics Data System (ADS)

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–1-90 km s–1 at z = 0. Meanwhile, the small-scale compressive ratio r 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, vpropk –0.89 and vpropk –2.02, while the total and dilatational velocity follow the scaling k –1.88 and k –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 ? b ~= 10-100, or T < 105.5 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; Feng, Long-long; Xia, Yinhua; Shu, Chi-Wang; Gu, Qiusheng; Fang, Li-Zhi

2013-11-01

135

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

NASA Astrophysics Data System (ADS)

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

Côté, Benoit; Martel, Hugo; Drissen, Laurent

2013-11-01

136

THE INTERGALACTIC STELLAR POPULATION FROM MERGERS OF ELLIPTICAL GALAXIES WITH DARK MATTER HALOS  

SciTech Connect

We present simulations of dry-merger encounters between pairs of elliptical galaxies with dark matter halos. The aim of these simulations is to study the intergalactic (IG) stellar populations produced in both parabolic and hyperbolic encounters. We model progenitor galaxies with total-to-luminous mass ratios M{sub T} /M{sub L}= 3 and 11. The initial mass of the colliding galaxies are chosen so that M{sub 1}/M{sub 2} = 1 and 10. The model galaxies are populated by particles representing stars, as in Stanghellini et al., and dark matter. Merger remnants resulting from these encounters display a population of unbounded particles, both dark and luminous. The number of particles becoming unbounded depends on orbital configuration, with hyperbolic encounters producing a larger luminous intracluster population than parabolic encounters. Furthermore, in simulations with identical orbital parameters, a lower M{sub T} /M{sub L} of the colliding galaxies produces a larger fraction of unbounded luminous particles. For each modeled collision, the fraction of unbounded to initial stellar mass is the same in all mass bins considered, similarly to what we found previously by modeling encounters of galaxies without dark halos. The fraction of IG to total luminosity resulting from our simulations is {approx}4% and {approx}6% for dark-to-bright mass ratios of 10 and 2, respectively. These unbounded-to-total luminous fractions are down from the 17% that we had previously found in the case of no dark halos. Our results are in broad agreement with IG light observed in groups of galaxies, while the results of our previous models without dark halos better encompass observed intracluster populations. We suggest a possible formation scenario of IG stars.

Gonzalez-Garcia, A. Cesar [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Stanghellini, Letizia [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Manchado, Arturo, E-mail: c.gonzalezgarcia@uam.e [Instituto de Astrofisica de Canarias, vIa Lactea s/n, La Laguna, E-38200 Tenerife (Spain)

2010-02-20

137

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

138

Time Delay of Cascade Radiation for TeV Blazars and the Measurement of the Intergalactic Magnetic Field  

Microsoft Academic Search

Recent claims that the strength B_{IGMF} of the intergalactic magnetic field\\u000a(IGMF) is >~ 1e-15 G are based on upper limits to the expected cascade flux in\\u000athe GeV band produced by blazar TeV photons absorbed by the extragalactic\\u000abackground light. This limit depends on an assumption that the mean blazar TeV\\u000aflux remains constant on timescales >~2e6 (B_{IGMF}\\/10^{-15} G)^2\\/(E\\/{10

Charles D. Dermer; Massimo Cavadini; Soebur Razzaque; Justin D. Finke; Benoit Lott

2010-01-01

139

Confirmation of X-ray Absorption by Warm-Hot Intergalactic Medium in the Sculptor Wall  

NASA Astrophysics Data System (ADS)

In a previous paper, we reported a 3? 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 ~ 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?, a substantial improvement over the 1.7? level reported previously when using only the Cycle-8 data. The significance increases to 4.0? 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 mÅ (90% confidence). We obtain a 90% lower limit on the O VII column density of 0.8 × 1016 cm-2 and a 90% upper limit on the Doppler b parameter of 460 km s-1. Assuming the absorber is uniformly distributed throughout the ~15 Mpc portion of the blazar's sight line that intercepts the Sculptor Wall, that the O VII column density is ?2 × 1016 cm-2 (corresponding to b >~ 150 km -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 ~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.; Canizares, Claude R.; Zappacosta, Luca; Maiolino, Roberto; Tagliaferri, Gianpiero; Gastaldello, Fabio

2010-05-01

140

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

141

Detection of extended He II reionization in the temperature evolution of the intergalactic medium  

NASA Astrophysics Data System (ADS)

We present new measurements of the temperature of the intergalactic medium (IGM) derived from the Ly? forest over 2.0 ?z? 4.8. The small-scale structure in the forest of 61 high-resolution quasi-stellar object spectra is quantified using a new statistic, the curvature, and the conversion to temperature calibrated using a suite of hydrodynamic simulations. At each redshift, we focus on obtaining the temperature at an optimal overdensity probed by the Ly? forest, ?, where the temperature is nearly a one-to-one function of the curvature regardless of the slope of the temperature-density relation. The median 2? statistical uncertainty in these measurements is 8 per cent, though there may be comparable systematic errors due to the unknown amount of Jeans smoothing in the IGM. We use our ? results to infer the temperature at the mean density, T0. Even for a maximally steep temperature-density relation, T0 must increase from ˜8000 K at z? 4.4 to ?12 000 K at z? 2.8. This increase is not consistent with the monotonic decline in T0 expected in the absence of He II reionization. We therefore interpret the observed rise in temperature as evidence of He II reionization beginning at z? 4.4. The evolution of T0 is consistent with an end to He II reionization at z˜ 3, as suggested by opacity measurements of the He II Ly? forest, although the redshift at which T0 peaks will depend somewhat on the evolution of the temperature-density relation. These new temperature measurements suggest that the heat input due to the reionization of He II dominates the thermal balance of the IGM over an extended period with ?z? 1. A part of the observations were 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. This paper also includes data gathered with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile.

Becker, George D.; Bolton, James S.; Haehnelt, Martin G.; Sargent, Wallace L. W.

2011-01-01

142

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

143

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

NASA Astrophysics Data System (ADS)

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

Bertone, Serena; Schaye, Joop

2012-01-01

144

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

NASA Astrophysics Data System (ADS)

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 Lamda = 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 NH I = 1015.3, 1013.5, and 1011.5 cm-2 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. We find that the column density distribution of Ly alpha forest lines can be fitted to f(N_{{H} {I}})~N^{- beta }_{{H} {I}} , with beta = 1.46 in the range 12.5 < log NH I < 14.5, matching recent Keck results. At somewhat higher column densities the distribution steepens, giving beta = 1.80 over the range 14.0 < log NH I < 15.5, matching earlier observations for these stronger lines. The normalization of the line numbers in our model also agrees with observations if the total baryon density is Omega b = 0.015 h-2 and the ionizing background intensity is J21 = 0.18. Alternatively, if J21 = 0.5 as recently estimated for the background due to observed quasars at z = 2.5, then Omega b = 0.025 h-2 yields the observed number of Ly alpha lines and the observed mean opacity. The model predicts that about 80% of the baryons in the universe are associated with Ly alpha forest features with 13 < log NH I < 15 at z = 3, while 10% are in more diffuse gas with smaller column densities and 10% are in higher column density clouds and in collapsed structures, such as galaxies and quasars. Our model requires that absorbers at z = 3 with column densities higher than about 1016 cm-2---Lyman limit systems and damped Ly alpha systems---represent a separate population that has collapsed out of the IGM. We find the number density of forest lines is dN/dz = 75[(1 + z)/4]2.5 for lines with EW > 0.32 Angstroms, also in good agreement with observations. We fit Voigt profiles to our simulated lines and find a distribution of b parameters that matches that obtained from similar fits to real spectra. The effective opacity in the Ly alpha forest is found from the model to be tau eff = 0.26[(1 + z)/4]3.1, again in good agreement with observations. The exponents for the evolution of the num

Bi, Hongguang; Davidsen, Arthur F.

1997-04-01

145

Galactic and intergalactic magnetic fields; Proceedings of the 140th Symposium of IAU, Heidelberg, Federal Republic of Germany, June 19-23, 1989  

Microsoft Academic Search

The present conference on galactic and intergalactic magnetic fields (MF) encompasses a survey of magnetic phenomena near the solar photosphere, the MF structure of the Galaxy, MFs in and around supernova remnants, magnetohydrodynamics of galactic MFs, the MF structure of external spiral galaxies, and MFs in molecular clouds. Also addressed are MFs in galactic nuclei, the role of MFs in

R. Beck; R. Wielebinski; P. P. Kronberg

1990-01-01

146

Release of protons with energy higher than 10 to the 18th eV from intergalactic magnetic field into interstellar magnetic field  

Microsoft Academic Search

Drift instabilities arising when accelerated protons are trapped in the intergalactic medium are examined. If alpha, the ratio of total (plasma+energetic particles) pressure and magnetic field pressure is larger than some value alphahbar ? 0.1 to 0.3, the magnetic trap is destroyed and protons are released into interstellar medium. If alpha < alphahbar, the trapped protons exhibit gradient instability due

A. K. Dasgupta

1983-01-01

147

High redshift in greatness scale caused by Interstellar and Intergalactic Media  

NASA Astrophysics Data System (ADS)

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

Chen, Shao-Guang

148

A study of the intergalactic magnetic field using extragalactic ultra-high-energy gamma-ray sources  

SciTech Connect

The possibility of measuring the intergalactic magnetic field between an extragalactic ultrahigh-energy (UHE) gamma-ray source and the Galaxy is considered. It is found that, if there is a strong UHE gamma-ray source at a distance of less than about 100 kpc, the magnetic field between the Galaxy and the source can be studied by UHE gamma-ray observations. If the field strength is less than 10 to the -12th G, the gamma-ray flux for E(gamma) greater than or equal to 10 to the 15th is enhanced about 10 times over that expected from the source energy spectrum and the absorption with the 3 K microwave background photons alone. 15 refs.

Honda, M.

1989-04-01

149

Interstellar and intergalactic gas towards SN 1993J in M 81: A study of optical and 21 CM spectra  

NASA Astrophysics Data System (ADS)

We present a study of the interstellar and intergalactic clouds located in the direction of the recent supernova 1993J in M81 based on the analysis of optical and 21 cm spectra obtained during the first nights after its discovery. The optical spectra were taken at high spectral resolution (FWHM 4 to 6 km/s) using the 4.2 m William Herschel Telescope (La Palma, Spain), covering the resonance lines of CN, Ca II, Ca I, CH(+), CH, Na I, Li I and K I. We also observed in Ca II a sample of foreground Galactic stars in the field of the supernova. The 21 cm spectra were taken with the 100 m Effelsberg Radiotelescope (beam FWHM approximately equals 9 min) at the position of SN 1993J and in 6 positions around the supernova, at 10 min separation.

Vladilo, G.; Centurion, M.; de Boer, K. S.; King, D. L.; Lipman, K.; Stegert, J. S. W.; Unger, S. W.; Walton, N. A.

1994-11-01

150

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

SciTech Connect

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

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

2011-09-10

151

Lower Bounds on Intergalactic Magnetic Fields from Simultaneously Observed GeV-TeV Light Curves of the Blazar Mrk 501  

Microsoft Academic Search

We derive lower bounds on intergalactic magnetic fields (IGMFs) from upper limits on the pair echo emission from the blazar Mrk 501, that is, delayed GeV emission from secondary e -- e + pairs produced via interactions of primary TeV gamma rays with the cosmic infrared background. Utilizing only simultaneous GeV-TeV light curves observed by VERITAS, MAGIC, and the Fermi

Keitaro Takahashi; Masaki Mori; Kiyotomo Ichiki; Susumu Inoue

2012-01-01

152

The Cosmological Impact of Luminous TeV Blazars I: Implications of Plasma Instabilities for the Intergalactic Magnetic Field and Extragalactic Gamma-Ray Background  

Microsoft Academic Search

Inverse-Compton cascades initiated by energetic gamma rays (E>100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic magnetic field (IGMF), and the stringent limits placed upon the unresolved extragalactic gamma-ray background (EGRB) by Fermi has been used to argue against a large number

Avery E. Broderick; Philip Chang; Christoph Pfrommer

2011-01-01

153

Advances in Astronomy and Space Physics, Proceedings of the 17th Young Scientists' Conference on Astronomy and Space Physics  

NASA Astrophysics Data System (ADS)

The present volume of Advances in Astronomy and Space Physics includes 29 papers presented during the 17th Young Scientists' Conference on Astronomy and Space Physics which was held at the Faculty of Physics of National Taras Shevchenko University of Kyiv, from April 26 till May 1, 2010. The conference is intended for participation of students, PhD students and young researches who are involved in research in one of the following fields: positional astronomy and astronomical equipment, atmospheric studies and space geophysics, plasma physics and physics of the near space, planetary systems and small bodies, solar physics and physics of heliosphere, stellar astrophysics, interstellar and intergalactic medium, extragalactic astrophysics, high-energy astrophysics, cosmology, computers in astronomy.

Editors: Choliy, V.; Ivashchenko, G.; Ivaniuk, O.

2011-01-01

154

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

NASA Astrophysics Data System (ADS)

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

Yang, Jianping; Wang, Jiancheng; Yang, Jianrong

2012-10-01

155

TIME DELAY OF CASCADE RADIATION FOR TeV BLAZARS AND THE MEASUREMENT OF THE INTERGALACTIC MAGNETIC FIELD  

SciTech Connect

Recent claims that the strength B{sub IGMF} of the intergalactic magnetic field (IGMF) is {approx}> 10{sup -15} G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background light. This limit depends on an assumption that the mean blazar TeV flux remains constant on timescales {approx}> 2(B{sub IGMF}/10{sup -18}G){sup 2}/(E/10 GeV){sup 2} yr for an IGMF coherence length {approx}1 Mpc, where E is the measured photon energy. Restricting TeV activity of 1ES 0229+200 to {approx}3-4 years during which the source has been observed leads to a more robust lower limit of B{sub IGMF} {approx}> 10{sup -18} G, which can be larger by an order of magnitude if the intrinsic source flux above {approx}5-10 TeV from 1ES 0229+200 is strong.

Dermer, Charles D.; Razzaque, Soebur; Finke, Justin D. [Space Science Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Cavadini, Massimo [Dipartimento di Fisica e Matematica, Universita dell'Insubria, via Valleggio 11, 22100, Como (Italy); Chiang, James [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Lott, Benoit, E-mail: charles.dermer@nrl.navy.mil [CNRS/IN2P3, Centre d' Etudes Nucleaires Bordeaux Gradignan, UMR 5797, Gradignan, 33175 (France)

2011-06-01

156

Radio Continuum Observations of NGC 1961: Interaction with the Intergalactic Medium or the Remnant of a Merger?  

NASA Astrophysics Data System (ADS)

We present new radio continuum images of the supermassive spiral galaxy NGC 1961 at 4 frequencies. Apart from its large mass (>1012 Modot) this galaxy possesses a peculiar optical morphology and an asymetric HI distribution with a large wing at one side. Our observations allow us to seperate the thermal and the nonthermal radio emission and to determine the nonthermal spectral index distribution. This spectral index distribution in the galactic disk is unusual: At the maxima of the radio emission the synchroton spectrum is very steep, indicating aged cosmic ray electrons. Away from the maxima the radio spectrum is much flatter. We discuss various possiblities to explain this peculiar behaviour and conclude that the most likely cause are fluctuations of the star formation rate in the past. The spectral index distribution furthermore suggests the presence of interstellar shocks where cosmic rays are accelerated. This additional acceleration could explain the excess of radio emission with respect to the far-infrared emission of NGC 1961. We suggest that a violent event in the past, most likely a collision with an intergalactic gas cloud or a merger, has caused the various unusual features of the galaxy.

Lisenfeld, U.; Alexander, P.; Pooley, G.

157

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

NASA Astrophysics Data System (ADS)

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. Numerous color illustrations are included.

French, B. M.; Maran, S. P.

158

16th Young Scientists' Conference on Astronomy and Space Physics  

NASA Astrophysics Data System (ADS)

The present Proceedings of Contributed Papers include 23 papers presented during 16th Young Scientists' Conference on Astronomy and Space Physics which was held at the Faculty of Physics of National Taras Shevchenko University of Kyiv, from April 27 till May, 2, 2009. The aim of the annual Open Young Scientists' Conference on Astronomy and Space Physics is to provide young scientists a possibility to communicate and present their scientific work. The conference is intended for participation of students, PhD students and young researches who are involved in research in one of the following fields: positional astronomy and astronomical equipment, atmospheric studies and geophysics, plasma physics and physics of the near space, planetary systems and small bodies, solar physics and physics of heliosphere, stellar astrophysics, interstellar and intergalactic medium, extragalactic astrophysics, high-energy astrophysics, cosmology, computers in astronomy and related to the mentioned above.

Choliy, V. Ya.; Ivashchenko, G.

2009-12-01

159

Eternity in six hours: Intergalactic spreading of intelligent life and sharpening the Fermi paradox  

NASA Astrophysics Data System (ADS)

The Fermi paradox is the discrepancy between the strong likelihood of alien intelligent life emerging (under a wide variety of assumptions) and the absence of any visible evidence for such emergence. In this paper, we extend the Fermi paradox to not only life in this galaxy, but to other galaxies as well. We do this by demonstrating that travelling between galaxies - indeed even launching a colonisation project for the entire reachable universe - is a relatively simple task for a star-spanning civilisation, requiring modest amounts of energy and resources. We start by demonstrating that humanity itself could likely accomplish such a colonisation project in the foreseeable future, should we want to. Given certain technological assumptions, such as improved automation, the task of constructing Dyson spheres, designing replicating probes, and launching them at distant galaxies, become quite feasible. We extensively analyse the dynamics of such a project, including issues of deceleration and collision with particles in space. Using similar methods, there are millions of galaxies that could have reached us by now. This results in a considerable sharpening of the Fermi paradox.

Armstrong, Stuart; Sandberg, Anders

2013-08-01

160

Soviet space  

NASA Astrophysics Data System (ADS)

A profusely illustrated history of the Soviet space program is presented. The topics addressed include: early Soviet rockets, satellites and planetary probes, cosmonauts in space, space stations, international cooperation in space, and the Soviet space program today and tomorrow.

Miller, Jay

161

THE LAST EIGHT-BILLION YEARS OF INTERGALACTIC C IV EVOLUTION  

SciTech Connect

We surveyed the Hubble Space Telescope UV spectra of 49 low-redshift quasars for z < 1 C IV candidates, relying solely on the characteristic wavelength separation of the doublet. After consideration of the defining traits of C IV doublets (e.g., consistent line profiles, other associated transitions, etc.), we defined a sample of 38 definite (group G = 1) and five likely (G = 2) doublets with rest equivalent widths W{sub r} for both lines detected at >=3sigma{sub W{sub r}}. We conducted Monte Carlo completeness tests to measure the unblocked redshift (DELTAz) and co-moving path length (DELTAX) over which we were sensitive to C IV doublets of a range of equivalent widths and column densities. The absorber line density of (G = 1+2) doublets is dN{sub C{sub IV}}/dX= 4.1{sup +0.7}{sub -0.6} for log N(C{sup +3}) >= 13.2, and dN{sub C{sub IV}}/dX has not evolved significantly since z = 5. The best-fit power law to the G = 1 frequency distribution of column densities f(N(C{sup +3}))ident tok(N(C{sup +3})/N{sub 0}){sup {alpha}{sub N}} has coefficient k = 0.67{sup +0.18}{sub -0.16} x 10{sup -14} cm{sup 2} and exponent {alpha}{sub N} = -1.50{sup +0.17}{sub -0.19}, where N{sub 0} = 10{sup 14} cm{sup -2}. Using the power-law model of f(N(C{sup +3})), we measured the C{sup +3} mass density relative to the critical density: OMEGA{sub C{sup +3}}= (6.20{sup +1.82}{sub -1.52})x10{sup -8} for 13 <= log N(C{sup +3}) <= 15. This value is a 2.8 +- 0.7 increase in OMEGA{sub C{sup +3}} compared to the error-weighted mean from several 1 < z < 5 surveys for C IV absorbers. A simple linear regression to OMEGA{sub C{sup +3}} over the age of the universe indicates that OMEGA{sub C{sup +3}} has slowly but steadily increased from z = 5 -> 0, with dOMEGA{sub C{sup +3}}/dt{sub age}= (0.42+-0.2)x10{sup -8} Gyr{sup -1}.

Cooksey, Kathy L.; Prochaska, J. Xavier [Department of Astronomy, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Thom, Christopher; Chen, Hsiao-Wen, E-mail: kcooksey@space.mit.ed, E-mail: cthom@stsci.ed, E-mail: hchen@oddjob.uchicago.ed, E-mail: xavier@ucolick.or [Department of Astronomy, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States)

2010-01-01

162

Mid-infrared spectroscopy of solids in relation to the composition of interstellar and intergalactic dust  

NASA Astrophysics Data System (ADS)

The chemical and physical information on the composition and nature of interstellar grains is a long-standing problem in astrophysics. This information can, in principle, be determined from infrared observations of astronomical sources. Whilst a spectral feature near lambda = 3.4 micron can be assigned unambiguously to CH stretching in organic material, features near the wavelengths 10 and 20 microns are open to several interpretations. Alternative explanations fall into two broad categories: C-C, C-O and C-N stretching in organic grains on the one hand, and Si-O stretching in mineral grains on the other. However, detailed comparison between laboratory spectra of various crystalline and amorphous silicates and the features in several astronomical objects, including circumstellar dust shells around cool stars, and in more extended sources as in the Trapezium nebula, are not satisfactory. In particular, silicates, whether they are of terrestrial or lunar origin, all show either too much structure or have their absorption peaks at the wrong wavelength. We obtained the infrared spectra of different organic, biological, and inorganic materials over the range 2.5-50 microns using a Perking-Elmer 783 series spectrophotometer. We compared these spectra with the 10 and 20 microns spectral features observed in objects in our galaxy and the external galaxies. A mixture of diatom silica with linked SiO4 tetrahedra together with organic grains characterized by the spectrum of an 'average' bacterium, provides excellent agreement with astronomical data relating to broad 10 and 20 microns emission and absorption features. Condensation of clay-like particles of radii 0.01 micron are most likely to occur in the atmospheres of Mira-type stars and be expelled by radiation pressure into interstellar space. These particles would tend to stick onto the surfaces of bacterial grains in conditions of high density associated with regions of star formation. The absorption and emission features at the 10 micron region of the circumstellar shell of cool carbon stars, OH/infrared sources, and the BN object, have been compared to that obtained from a composite model comprised of red crystal, diatom-silica, and 'average' bacteria. Good agreement between the astronomical data for these sources and the model has been obtained.

Majeed, Qasim S.

163

The Hubble Space Telescope and Laboratory Astrophysics  

NASA Astrophysics Data System (ADS)

The Hubble Space Telescope (HST) 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 on the recent successful servicing mission SM4, offer imaging from near-infrared through ultra- violet 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 y in 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. This paper provides an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics. With no current plans for further servicing of Hubble (and thus limited further observations), and no future major optical/UV space observatory currently planned for at least the next decade, it is essential to maximize the critical laboratory astrophysics support needed for Hubble observations in the near-term.

Wiseman, J. J.

2011-05-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

166

THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. II. REWRITING THE THERMAL HISTORY OF THE INTERGALACTIC MEDIUM  

SciTech Connect

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

Chang, Philip; Broderick, Avery E.; Pfrommer, Christoph, E-mail: aeb@cita.utoronto.ca, E-mail: pchang@cita.utoronto.ca, E-mail: christoph.pfrommer@h-its.org [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

2012-06-10

167

Intergalactic magnetic fields  

Microsoft Academic Search

There is no observational support to the hypothesis of the most large-scale homogeneous magnetic field in the Universe. The best upper limit is given by interpretation of the Faraday rotation from the extragalactic radio sources. However the magnetic fields can be generated in the clusters of galaxies by a turbulence in the wakes of moving galaxies. These fields have an

A. A. Ruzmajkin

1991-01-01

168

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

169

A New Method to Directly Measure the Jeans Scale of the Intergalactic Medium Using Close Quasar Pairs  

NASA Astrophysics Data System (ADS)

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 0 and slope ? of the temperature-density relation of the IGM T=T_0(\\rho / {\\bar{\\rho }})^{\\gamma -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.; White, Martin

2013-10-01

170

Lower Bounds on Intergalactic Magnetic Fields from Simultaneously Observed GeV-TeV Light Curves of the Blazar Mrk 501  

NASA Astrophysics Data System (ADS)

We derive lower bounds on intergalactic magnetic fields (IGMFs) from upper limits on the pair echo emission from the blazar Mrk 501, that is, delayed GeV emission from secondary e - e + pairs produced via interactions of primary TeV gamma rays with the cosmic infrared background. Utilizing only simultaneous GeV-TeV light curves observed by VERITAS, MAGIC, and the Fermi Large Area Telescope during a multiwavelength campaign in 2009 that included a TeV flare, bounds are deduced on the IGMF strength of B >~ 10-20 G at the 90% confidence level for a field coherence length of 1 kpc. Since our analysis is based firmly on the observational data alone and is nearly free of assumptions concerning the primary TeV flux in unobserved periods or spectral bands, our evaluation of the pair echo flux is conservative and the evidence for a non-zero IGMF is more robust compared to previous studies.

Takahashi, Keitaro; Mori, Masaki; Ichiki, Kiyotomo; Inoue, Susumu

2012-01-01

171

THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND  

SciTech Connect

Inverse Compton cascades (ICCs) initiated by energetic gamma rays (E {approx}> 100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic magnetic field (IGMF), and the stringent limits placed on the unresolved extragalactic gamma-ray background (EGRB) by Fermi have been used to argue against a large number of such objects at high redshifts. However, these are predicated on the assumption that inverse Compton scattering is the primary energy-loss mechanism for the ultrarelativistic pairs produced by the annihilation of the energetic gamma rays on extragalactic background light photons. Here, we show that for sufficiently bright TeV sources (isotropic-equivalent luminosities {approx}> 10{sup 42} erg s{sup -1}) plasma beam instabilities, specifically the 'oblique' instability, present a plausible mechanism by which the energy of these pairs can be dissipated locally, heating the intergalactic medium. Since these instabilities typically grow on timescales short in comparison to the inverse Compton cooling rate, they necessarily suppress the ICCs. As a consequence, this places a severe constraint on efforts to limit the IGMF from the lack of a discernible GeV bump in TeV sources. Similarly, it considerably weakens the Fermi limits on the evolution of blazar populations. Specifically, we construct a TeV-blazar luminosity function from those objects currently observed and find that it is very well described by the quasar luminosity function at z {approx} 0.1, shifted to lower luminosities and number densities, suggesting that both classes of sources are regulated by similar processes. Extending this relationship to higher redshifts, we show that the magnitude and shape of the EGRB above {approx}10 GeV are naturally reproduced with this particular example of a rapidly evolving TeV-blazar luminosity function.

Broderick, Avery E.; Chang, Philip; Pfrommer, Christoph, E-mail: aeb@cita.utoronto.ca, E-mail: pchang@cita.utoronto.ca, E-mail: christoph.pfrommer@h-its.org [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

2012-06-10

172

The Cosmological Impact of Luminous TeV Blazars. I. Implications of Plasma Instabilities for the Intergalactic Magnetic Field and Extragalactic Gamma-Ray Background  

NASA Astrophysics Data System (ADS)

Inverse Compton cascades (ICCs) initiated by energetic gamma rays (E >~ 100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic magnetic field (IGMF), and the stringent limits placed on the unresolved extragalactic gamma-ray background (EGRB) by Fermi have been used to argue against a large number of such objects at high redshifts. However, these are predicated on the assumption that inverse Compton scattering is the primary energy-loss mechanism for the ultrarelativistic pairs produced by the annihilation of the energetic gamma rays on extragalactic background light photons. Here, we show that for sufficiently bright TeV sources (isotropic-equivalent luminosities >~ 1042 erg s-1) plasma beam instabilities, specifically the "oblique" instability, present a plausible mechanism by which the energy of these pairs can be dissipated locally, heating the intergalactic medium. Since these instabilities typically grow on timescales short in comparison to the inverse Compton cooling rate, they necessarily suppress the ICCs. As a consequence, this places a severe constraint on efforts to limit the IGMF from the lack of a discernible GeV bump in TeV sources. Similarly, it considerably weakens the Fermi limits on the evolution of blazar populations. Specifically, we construct a TeV-blazar luminosity function from those objects currently observed and find that it is very well described by the quasar luminosity function at z ~ 0.1, shifted to lower luminosities and number densities, suggesting that both classes of sources are regulated by similar processes. Extending this relationship to higher redshifts, we show that the magnitude and shape of the EGRB above ~10 GeV are naturally reproduced with this particular example of a rapidly evolving TeV-blazar luminosity function.

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

2012-06-01

173

Themed Space  

ERIC Educational Resources Information Center

|This article presents a classroom activity that introduces students to the concept of themed space. Students learn to think critically about the spaces they encounter on a regular basis by analyzing existing spaces and by working in groups to create their own themed space. This exercise gives students the chance to see the relevance of critical…

Lynch, Christopher O.

2010-01-01

174

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).

175

Space Stuff  

NSDL National Science Digital Library

Students are introduced to general space science with information about astronauts, space probes, space travel, the Hubble Space Telescope, space suits, and the Columbia Shuttle accident. Biographies of important scientists and astronauts are included, and vocabulary crossword puzzles, maps, logic riddles, and coloring pages extend learning. Each page offers links to a glossary of important terms. A link to content for more advanced students is included.

176

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.

177

Space Industry.  

National Technical Information Service (NTIS)

The U.S. space industry is a product of Government necessity born of national security imperatives. From its inception, space has provided competitive advantages to the United States in terms of national security, national pride, and technological superio...

J. D. Estridge K. D. Biddlecombe M. Bailey P. F. Frakes R. Campos

2006-01-01

178

Space basic  

NASA Astrophysics Data System (ADS)

In this education video series, 'Liftoff to Learning', astronauts (Bruce Melnick, Thomas Akers, William Shepherd, Robert Cabana, and Richard Richards) describe the historical beginnings of space exploration from the time of Robert H. Goddard (considered the Father of Rocketry), who, in 1929, invented the first propellant rocket, the prototype of modern liquid propellant rockets, up to the modern Space Shuttles. The questions - where is space, what is space, and how do astronauts get to, stay in, and come back from space are answered through historical footage, computer graphics, and animation. The space environment effects, temperature effects, and gravitational effects on the launching, orbiting, and descent of the Shuttles are discussed. Included is historical still photos and film footage of past space programs and space vehicles.

Herbert, Dexter

1991-01-01

179

Multipurpose Spaces  

ERIC Educational Resources Information Center

|The concept of multipurpose spaces in schools is certainly not new. Especially in elementary schools, the combination of cafeteria and auditorium (and sometimes indoor physical activity space as well) is a well-established approach to maximizing the use of school space and a school district's budget. Nonetheless, there continue to be refinements…

Gordon, Douglas

2010-01-01

180

Space Froggy  

NSDL National Science Digital Library

Help Captain Space Froggy and his family escape from a top secret lab located on the Space Station "Fluffy" above the Earth. To escape they must first cross the busy docking ramp and then traverse deep space landing on one of the transporter pads.

2010-01-01

181

Space Suit.  

National Technical Information Service (NTIS)

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 i...

A. J. Kenneway G. P. Durney L. F. Shepard M. C. Case R. C. Wise

1973-01-01

182

The Production of Cosmic Gamma Rays in Interstellar and Intergalactic Cosmic-Ray Collisions. II: the Effects of the Decay of Nucleon Isobars and Hyperons on the Cosmic Gamma-Ray Spectrum  

Microsoft Academic Search

In interstellar and intergalactic cosmic-ray proton-proton collisions it is possible to produce nucleon isobars and hypersons that carry off a large fraction of the energy available in the collision. The delayed gamma rays that result from the decay of these particles also carry a large fraction of the available gamma-ray energy. We have calculated the galactic gamma-ray spectrum due to

F. W. Stecker; S. Tsuruta; G. G. Fazio

1967-01-01

183

Space Communication  

NASA Astrophysics Data System (ADS)

As the space era approaches, the importance of including space science in the general curriculum and communicating space science to the general public is becoming extremely important. The paper, points out that the inclusion of more space education in the school curriculum and to the general public will increase awareness and interest in the new developments of space exploration. The paper covers some of the many science communication projects under taken by students in the UK. One such success was the contribution to National Science Week by the University of Leicester in conjunction with UK Students for the Exploration and Development of Space (UKSEDS - a national body of students promoting space education). Children between the ages of 9-12 were taught about the solar system using enjoyable experiments. The paper will also cover other UKSEDS activities and projects. On a more worldwide scale `Under African Skies' is a fairly new and immensely exciting project (part of Cosmos Education): the participants last year including UKSEDS members travelled from school to school in Africa helping teachers and taking part in classes, including many in astronomy and physics. The paper also explains the benefits of the National Space Centre in the UK, the involvement of the University of Leicester in SSETI (Student Space Exploration and Technology Initiative) and Space School.

Patel, Bhavini

2002-01-01

184

LOWER BOUNDS ON INTERGALACTIC MAGNETIC FIELDS FROM SIMULTANEOUSLY OBSERVED GeV-TeV LIGHT CURVES OF THE BLAZAR Mrk 501  

SciTech Connect

We derive lower bounds on intergalactic magnetic fields (IGMFs) from upper limits on the pair echo emission from the blazar Mrk 501, that is, delayed GeV emission from secondary e{sup -}e{sup +} pairs produced via interactions of primary TeV gamma rays with the cosmic infrared background. Utilizing only simultaneous GeV-TeV light curves observed by VERITAS, MAGIC, and the Fermi Large Area Telescope during a multiwavelength campaign in 2009 that included a TeV flare, bounds are deduced on the IGMF strength of B {approx}> 10{sup -20} G at the 90% confidence level for a field coherence length of 1 kpc. Since our analysis is based firmly on the observational data alone and is nearly free of assumptions concerning the primary TeV flux in unobserved periods or spectral bands, our evaluation of the pair echo flux is conservative and the evidence for a non-zero IGMF is more robust compared to previous studies.

Takahashi, Keitaro [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Mori, Masaki [Department of Physical Sciences, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan); Ichiki, Kiyotomo [Department of Physics and Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Inoue, Susumu, E-mail: keitaro@sci.kumamoto-u.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582 (Japan)

2012-01-15

185

Learning Spaces  

NSDL National Science Digital Library

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

Oblinger, Diana

2010-07-12

186

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

187

Conceptual Spaces  

Microsoft Academic Search

Spaces exist in the mind as well as on land and sea. They cannot be seen, or traversed by ship or on foot, not even with seven-league\\u000a boots. For they are abstract spaces, or styles of thinking. But although the geographer's methods of dealing with terrestrial\\u000a space do not reliably apply to the conceptual realm, there are other methods with

Margaret A. Boden

188

Noncommutative Spaces  

Microsoft Academic Search

In this chapter we present some of the basic concepts needed to describe noncommutative spaces and their topological and geometrical\\u000a features. We therefore complement the previous chapters where noncommutative spaces have been described by the commutation\\u000a relations of their coordinates. The full algebraic description of ordinary (commutative) spaces requires the completion of\\u000a the algebra of coordinates into a \\u000a C*<\\/font\\u000a>C^\\\\star

Fedele Lizzi

2009-01-01

189

Collaborative Spaces  

ERIC Educational Resources Information Center

|When architects discuss the educational facilities of the next century and beyond, the conversation turns to collaborative spaces. They envision flexible and fluid spaces that will encourage creative and critical thinking, and free students to communicate clearly about the task at hand. While these are admirable ideals, there are some fundamental…

Lippman, Peter C.

2013-01-01

190

Space Handbook.  

National Technical Information Service (NTIS)

The responsibilities of the Air Force in space include a large and growing number of functions that contribute to the defense of the United States. Space operations are important elements of a credible deterrent to armed conflict. In the near-term, should...

C. D. Cochran D. M. Gorman J. D. Dumoulin

1985-01-01

191

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.

192

Space Debris  

NSDL National Science Digital Library

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

2008-02-26

193

Space Review.  

National Technical Information Service (NTIS)

Human space flight in the US and other space-faring countries is faced with a twin challenge that is likely to persist for many years: flat or declining budgets along with an expectation of continuing, significant achievements. A partial solution may invo...

D. Lester H. Thronson S. Hatfield

2011-01-01

194

Space flight  

NASA Astrophysics Data System (ADS)

Wayne Littles will take over the job of Associate Administrator for Space Flight at NASA from Maj.Gen. Jeremiah W. Pearson, who has resigned from the post. Littles, now NASA's Chief Engineer, was formerly deputy director of the Marshall Space Flight Center in Huntsville, Ala.

195

Space Weather  

NASA Astrophysics Data System (ADS)

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

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

196

Space Weather  

NASA Astrophysics Data System (ADS)

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

Lanzerotti, L. J.

2005-05-01

197

Space making  

NASA Astrophysics Data System (ADS)

With discoveries from Mars, the Hubble Deep Field, and Ganymede reawakening Washington's interest in space, the U.S. federal government has started fine-tuning its stance on space flight and exploration. The attention comes as prelude to a proposed November meeting to discuss astronomical and planetary discoveries, and to a rumored space summit in December between Vice President Al Gore and congressional leaders.On September 17, the House of Representatives passed by voice vote H.R. 3936, the Space Commercialization Promotion Act. A measure with strong bipartisan support, the bill officially encourages private companies to participate in the space industry and requires NASA to find more ways to work with the private sector. Updating and amending several existing U.S. policies about commerce in space, H.R. 3936 gives the Department of Transportation the authority to provide and administer licenses for commercial spacecraft to reenter American airspace from orbit and outer space. It also prods NASA to purchase scientific data about the Earth and the solar system from the private sector, whenever possible.

Carlowicz, Michael

198

THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z {approx} 4: IMPLICATIONS FOR IONIZATION OF THE INTERGALACTIC MEDIUM AND COSMIC DOWNSIZING  

SciTech Connect

We present an updated determination of the z {approx} 4 QSO luminosity function (QLF), improving the quality of the determination of the faint end of the QLF presented by Glikman et al. (2010). We have observed an additional 43 candidates from our survey sample, yielding one additional QSO at z = 4.23 and increasing the completeness of our spectroscopic follow-up to 48% for candidates brighter than R = 24 over our survey area of 3.76 deg{sup 2}. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 A compared with measuring M{sub 1450} directly from the object spectra. We find a luminosity-dependent bias: template-based K-corrections overestimate the luminosity of low-luminosity QSOs, likely due to their reliance on templates derived from higher luminosity QSOs. Combining our sample with bright quasars from the Sloan Digital Sky Survey and using spectrum-based M{sub 1450} for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, {alpha} = 3.3 {+-} 0.2, and faint-end slope, {beta} = 1.6{sup +0.8}{sub -0.6}. Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z {approx} 3. The break luminosity, though poorly constrained, is at M* = -24.1{sup +0.7}{sub -1.9}, approximately 1-1.5 mag fainter than at z {approx} 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts.

Glikman, Eilat; Lee, Kyoung-Soo [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Djorgovski, S. G. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Dey, Arjun; Jannuzi, Buell T., E-mail: eilat.glikman@yale.edu [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States)

2011-02-20

199

The Santa Fe Light Cone Simulation Project. I. Confusion and the Warm-Hot Intergalactic Medium in Upcoming Sunyaev-Zel'dovich Effect Surveys  

NASA Astrophysics Data System (ADS)

We present the first results from a new generation of simulated large sky coverage (~100 deg2) Sunyaev-Zel'dovich effect (SZE) cluster surveys using the cosmological adaptive mesh refinement N-body/hydro code Enzo. We have simulated a very large (5123 h-3 Mpc3) volume with unprecedented dynamic range. We have generated simulated light cones to match the resolution and sensitivity of current and future SZE instruments. Unlike many previous studies of this type, our simulation includes unbound gas, where an appreciable fraction of the baryons in the universe reside. We have found that cluster line-of-sight overlap may be a significant issue in upcoming single-dish SZE surveys. Smaller beam surveys (~1') have more than one massive cluster within a beam diameter 5%-10% of the time, and a larger beam experiment like Planck has multiple clusters per beam 60% of the time. We explore the contribution of unresolved halos and unbound gas to the SZE signature at the maximum decrement. We find that there is a contribution from gas outside clusters of ~16% per object, on average, for upcoming surveys. This adds both bias and scatter to the deduced value of the integrated SZE, increasing difficulty in accurately calibrating a cluster Y-M relationship. Finally, we find that in images where objects with M>5×1013 Msolar have had their SZE signatures removed, roughly a third of the total SZE flux remains. This gas exists at least partially in the warm-hot intergalactic medium (WHIM) and will possibly be detectable with the upcoming generation of SZE surveys.

Hallman, Eric J.; O'Shea, Brian W.; Burns, Jack O.; Norman, Michael L.; Harkness, Robert; Wagner, Rick

2007-12-01

200

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

201

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

202

Space Rescue.  

National Technical Information Service (NTIS)

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...

J. F. Muratore

2007-01-01

203

Space design  

Microsoft Academic Search

Space stations, Moon bases and Mars bases are artificial habitats intended to support human life in extreme conditions. Their\\u000a purpose is to pursue human progress and to gain knowledge and experience of the environment surrounding our planet. This research\\u000a focuses on visual investigation in order to improve interface design in space habitat interiors. The subject of this article\\u000a is why

Irene Lia Schlacht; Henrik Birke

2011-01-01

204

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

205

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

206

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.

207

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

208

Space Weaponization.  

National Technical Information Service (NTIS)

The world may be on the verge of a new era of warfare, one where battles are not fought only within the biosphere of the Earth, but also in the space surrounding it. Recent conflicts have shown the tremendous advantages conferred upon those who have the a...

W. H. Callahan

2000-01-01

209

Space Technospheres  

Microsoft Academic Search

Two main tendencies of making the Solar System habitable are regarding nowadays: (1) making objects of the Solar System habitable; and (2) making the space of the Solar System habitable. We think that it's better to combine them. We should dezine and build settlements ('technospheres') on such objects as asteroids and comets, using their resources. That is, it is necessary

A. P. Vidmachenko; A. F. Steklov; N. V. Primak

2000-01-01

210

Space reactors  

Microsoft Academic Search

Progress in technology development for the Space Power Advanced Reactor (SPAR) project is reported. The weights of neutron and gamma shields required to protect the SPAR system payloads for a range of permissible exposures was determined, and initial results are reported. SPAR reactor safety in the case of water immersion was modeled. Approval in principle was received for the SPAR

W. A. Ranken

1982-01-01

211

Space Geodesy  

NASA Astrophysics Data System (ADS)

Geodesy is the science studying the size and the figure of the Earth including the determination of the Earth's gravitational field. Geodetic astronomy is that part of astronomy dealing with the definition and realization of a terrestrial and a celestial reference frame (see TERRESTRIAL COORDINATE SYSTEMS AND FRAMES). By space geodesy we mean, then, those aspects of geodesy and geodetic astronomy...

Beutler, G.; Murdin, P.

2000-11-01

212

The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >= 5: evidence for a photon-starved and extended epoch of reionization  

NASA Astrophysics Data System (ADS)

Galaxies and quasars are thought to provide the bulk of the photons responsible for ionizing the hydrogen in the intergalactic medium (IGM). We use a large set of hydrodynamical simulations, combined with measurements of the Ly? opacity of the IGM taken from the literature, to obtain robust estimates of the photoionization rate per hydrogen atom at z = 5 and 6. We find the photoionization rate drops by a factor of 2 and 4, respectively, compared to our recent measurements at z = 2-4. The number of ionizing photons emitted by known sources at z = 5 and 6, based on an extrapolation of source numbers below the detection limit and standard assumptions for the relationship between the ionizing emissivity and observed luminosity density at 1500 Å, are in reasonable agreement with the photoionization rates inferred from the Ly? forest if the escape fraction of ionizing photons from galaxies is large (>~20 per cent). The expected number of ionizing photons from observed sources at these redshifts therefore appears sufficient to maintain the IGM in its highly ionized state. Claims to the contrary may be attributed to the adoption of an unduly high value for the clumping factor of ionized hydrogen. Using physically motivated assumptions for the mean free path of ionizing photons our measurements of the photoionization rate can be turned into an estimate of the ionizing emissivity. In comoving units the inferred ionizing emissivity is nearly constant over the redshift range 2-6 and corresponds to 1.5-3 photons emitted per hydrogen atom over a time interval corresponding to the age of the Universe at z = 6. This strongly suggests that the epoch of reionization was photon-starved and extended. Completion of reionization at or before z = 6 requires either an emissivity which rises towards higher redshifts or one which remains constant but is dominated by sources with a rather hard spectral index. For standard assumptions, the ionizing emissivity required for completion of reionization at or before z = 6 lies at the upper end of recently reported values from searches for high-redshift galaxies at z = 8-10.

Bolton, James S.; Haehnelt, Martin G.

2007-11-01

213

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.

214

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

215

Narrative Spaces  

Microsoft Academic Search

Game designers don’t simply tell stories; they design worlds and sculpt spaces. It is no accident, for example, that game\\u000a designers have historically been more interested in issues of level design than of plot or character motivation. A prehistory\\u000a of video and computer games might take us through the evolution of paper mazes or board games, both preoccupied with the

Henry Jenkins

216

Space Shuttle  

Microsoft Academic Search

The development of the Space Shuttle is reviewed, and major design features of the initial Orbiter OV-101, now under construction, are summarized. The aerodynamic aspects of the double-delta wing platform and the short fuselage design are discussed. The thermal protection system, designed to cope with temperatures up to 2300 F, is detailed, with special attention to the quartz-based high-temperature reusable

M. Wilson

1975-01-01

217

Space reactors  

Microsoft Academic Search

Progress in design studies and technology for the SP-100 Project - successor to the Space Power Advanced Reactor (SPAR) Project - is reported for the period October 1, 1981 to March 31, 1982. The basis for selecting a high-temperature, UO2-fueled, heat-pipe-cooled reactor with a thermoelectric conversion system as the 100\\/kW-sub e\\/ reference design has been reviewed. Although no change has

W. A. Ranken

1983-01-01

218

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.

219

Space propulsion  

NASA Astrophysics Data System (ADS)

Lewis Research Center is developing broad-based new technologies for space chemical engines to satisfy long-term needs of ETO launch vehicles and other vehicles operating in and beyond Earth orbit. Specific objectives are focused on high performance LO2/LH2 engines providing moderate thrusts of 7,5-200 klb. This effort encompasses research related to design analysis and manufacturing processes needed to apply advanced materials to subcomponents, components, and subsystems of space-based systems and related ground-support equipment. High-performance space-based chemical engines face a number of technical challenges. Liquid hydrogen turbopump impellers are often so large that they cannot be machined from a single piece, yet high stress at the vane/shroud interface makes bonding extremely difficult. Tolerances on fillets are critical on large impellers. Advanced materials and fabricating techniques are needed to address these and other issues of interest. Turbopump bearings are needed which can provide reliable, long life operation at high speed and high load with low friction losses. Hydrostatic bearings provide good performance, but transients during pump starts and stops may be an issue because no pressurized fluid is available unless a separate bearing pressurization system is included. Durable materials and/or coatings are needed that can demonstrate low wear in the harsh LO2/LH2 environment. Advanced materials are also needed to improve the lifetime, reliability and performance of other propulsion system elements such as seals and chambers.

Kazaroff, John M.

1993-02-01

220

America plans for space  

SciTech Connect

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

Not Available

1986-01-01

221

Commercial Space Tourism and Space Weather  

Microsoft Academic Search

Space tourism, a concept which even a few years ago was perveived as science fantasy, is now a credible industry. Five individuals have paid up to $25 M to spend more than a week on the International Space Station. Several enterprises are working toward viable suborbital and orbital private space operations. while operational space weather support to human space flight

Ronald Turner

2007-01-01

222

Open Spaces  

NSDL National Science Digital Library

Recently, the U.S. Fish & Wildlife Service created the "Open Spaces" blog to showcase some of their wildlife refuges and to offer the general public an inside view on the day-to-day operations of the organization. Visitors to the site will find blog posts that profile their work in the Everglades, reflections on September 11th, migratory birds, and the Labrador retrievers that work at the Kenai National Wildlife Refuge in Alaska. Users of the site can search posts by category, and they will find that each entry also contains a selection of links to other materials, such as park management plans and lesson plans. Finally, visitors can also use the social media buttons here to share each post on Twitter and Facebook.

223

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

224

Space weather and deep space communications  

Microsoft Academic Search

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

Richard Woo

2007-01-01

225

Esrange Space Center, a Gate to Space  

Microsoft Academic Search

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

Ola Widell

2008-01-01

226

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.

Lownsbrough, Hannah; Beunderman, Joost

2007-07-01

227

"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

228

"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

229

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.

230

How can laboratory plasma experiments contribute to space and &astrophysics?  

NASA Astrophysics Data System (ADS)

Plasma physics plays key role in a wide range of phenomena in the universe, from laboratory plasmas to the magnetosphere, the solar corona, and to the tenuous interstellar and intergalactic gas. Despite the huge difference in physical scales, there are striking similarities in plasma behavior of laboratory and space plasmas. Similar plasma physics problems have been investigated independently by both laboratory plasma physicists and astrophysicists. Since 1991, cross fertilization has been increased among laboratory plasma physicists and space physicists through meeting such as IPELS [Interrelationship between Plasma Experiments in the Laboratory and Space] meeting. The advances in laboratory plasma physics, along with the recent surge of astronomical data from satellites, make this moment ripe for research collaboration to further advance plasma physics and to obtain new understanding of key space and astrophysical phenomena. The recent NRC review of astronomy and astrophysics notes the benefit that can accrue from stronger connection to plasma physics. The present talk discusses how laboratory plasma studies can contribute to the fundamental understandings of the space and astrophysical phenomena by covering common key physics topics such as magnetic reconnection, dynamos, angular momentum transport, ion heating, and magnetic self-organization. In particular, it has recently been recognized that "physics -issue- dedicated" laboratory experiments can contribute significantly to the understanding of the fundamental physics for space-astrophysical phenomena since they can create fundamental physics processes in controlled manner and provide well-correlated plasma parameters at multiple plasma locations simultaneously. Such dedicated experiments not only can bring about better understanding of the fundamental physics processes but also can lead to findings of new physics principles as well as new ideas for fusion plasma confinement. Several dedicated experiments have provided the fundamental physics data for magnetic reconnection [1]. Linear plasma devices have been utilized to investigate Whistler waves and Alfven wave phenomena [2,3]. A rotating gallium disk experiment has been initiated to study magneto-rotational instability [4]. This talk also presents the most recent progress of these dedicated laboratory plasma research. 1. M. Yamada et al., Phys. Plasmas 4, 1936, (1997) 2. R. Stenzel, Phys. Rev. Lett. 65, 3001 (1991) 3. W. Gekelman et al, Plasma Phys. Contr. Fusion, v42, B15-B26, Suppl.12B (2000) 4. H. Ji, J. Goodman, A. Kageyama Mon. Not. R. Astron. Soc. 325, L1- (2001)

Yamada, M.

231

The Physical Conditions and Metal Enrichment of Low-Redshift Interstellar and Intergalactic Media: The Benefits of High-Resolution Ultraviolet Spectra  

Microsoft Academic Search

To underscore the value of high spectral resolution for the study of low-z QSO absorption lines, we briefly present Space Telescope Imaging Spectrograph echelle data that demonstrate how increased resolution leads to dramatic improvement in line measurements. We show that even R = lambda\\/Delta lambda = 20,000 is insufficient for some measurements. The higher the resolution the better, but R

T. M. Tripp; David V. Bowen

2003-01-01

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

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

234

Canadian space robotic activities  

Microsoft Academic Search

The Canadian Space Agency has chosen space robotics as one of its key niche areas, and is currently preparing to deliver the first flight elements for the main robotic system of the international space station.The Mobile Servicing System (MSS) is the Canadian contribution to the international space station. It consists of three main elements. The Space Station Remote Manipulator System

Christian Sallaberger

1997-01-01

235

European Space Camp  

Microsoft Academic Search

Despite a considerable growth in space related industry and scientific research over the past few decades, space related education has largely been neglected in our country. NAROM - the National Centre for Space Related Education - was formed in 2000 to organize space related educational activities, to promote recruitment, to promote appreciation for the benefits of space activities, and to

Arne Hjalmar Hansen; Per Stian Bendiksen; Kjetil Henninen

2003-01-01

236

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

237

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

238

Space Policy Perspectives of Young Space Professionals  

NASA Astrophysics Data System (ADS)

Space policy, particularly international policies on the military and peaceful uses of space, was a main topic of discussion at the Space Generation Forum (SGF), UNISPACE-III. Ideas and recommendations on this topic are being further developed at the Space Generation Summit (SGS), an event at World Space Congress (WSC) that will unite international students and young professionals to develop a youth vision and strategy for the peaceful uses of space. SGS, endorsed by the United Nations, will take place from October 11-13th, during which the 200 delegates will discuss ongoing youth space activities, particularly those stemming from the UNISPACE-III/SGF and taken forward by the Space Generation Advisory Council. Delegates will address a variety of topics with the goal of devising new recommendations according to the theme, 'Accelerating Our Pace in Space'. The material presented here and in other technical sessions throughout WSC includes the findings of these discussions. In this paper, we present the work to date on consolidating the views of young space professionals regarding the military uses of space. We also discuss the recommendations made that are pertinent to this session and highlight the proposed channels for their implementation. One area discussed in this paper and of particular interest to the youth is the use of military space technology for civilian and peaceful purposes.

Marshall, W.

2002-01-01

239

Moving From Problem Space to Solution Space  

Microsoft Academic Search

Extracting and elaborating software requirements and transforming them into viable software architecture are still an intricate task. This paper defines a solution architecture which is based on the blurred amalgamation of problem space and solution space. The dependencies between domain constraints, requirements and architecture and their importance are described that are to be considered collectively while evolving from problem space

Bilal Saeed Raja; M. Ali Iqbal; Imran Ihsan

240

NASA Space Shuttle Processing.  

National Technical Information Service (NTIS)

This viewgraph presentation reviews NASA's Space Shuttle Processing at Kennedy Space Center. A demonstration of the Space Shuttle silica tiles, a description of its High Temperature Reusable Surface Insulation (HRSI), tile inspections, and tile replacemen...

L. L. Andruske

2010-01-01

241

Animals in Space.  

National Technical Information Service (NTIS)

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 obt...

A. White

1988-01-01

242

The Second Space Race  

NASA Astrophysics Data System (ADS)

This paper compares and contrasts the characteristics of the first space race, which ran from the late 1950s to the late 1990s, and the second space race that began with the successful space flight of SpaceShipOne in 2004. The first space race was between superpowers seeking to establish geo-political dominance in the Cold War. The second space race will be between competing companies seeking to establish low cost access to space for ordinary people. The first space race achieved its geo- political objectives but did not open up low cost access to space but rather restricted access to a select few, highly trained astronauts and cosmonauts. The second space race, driven by the size and growth of the travel and tourism industry, promises to open up access to space to millions of space tourists.

Fawkes, S.

243

Space Solar Power Program  

SciTech Connect

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

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

1992-08-01

244

Momentum-space representation in curved space  

SciTech Connect

A non-Hermitian momentum-space representation of functions of a manifold (curved space) isomorphic to {ital R}{sup {ital n}} is constructed out of pure plane waves. We prove the covariance of the coordinate- and momentum-space representations. We give the momentum-space representation of the trace of operators. In interacting field theory this representation enables us to calculate the part of the effective action that encodes local properties of a general curved space. Thus the trace anomaly and the beta function can be evaluated. An explicit calculation is displayed at one loop for a scalar field coupled to gravity. In flat space the formalism applies to Cartesian and curvilinear coordinates. Application to the study of the stability of the vacuum of a field theory in curved space is possible.

Carreau, M. (Center for Theoretical Physics, Laboratory for Nuclear Science, Cambridge, Massachusetts 02139 (US))

1989-09-15

245

The Complex Semantic Space Model  

Microsoft Academic Search

The cyber-physical society is a complex space where human abilities are extended to various spaces by coordinating the cyber space, physical space, socio space and mental space. A challenge issue is to seek the uniformity in managing resources in these spaces. This keynote introduces a complex semantic space model that is suitable for managing various resources in different spaces in

Hai Zhuge

2011-01-01

246

National Space Policy and Space Weather  

NASA Astrophysics Data System (ADS)

The new national space policy, authorized by President Bush on 31 August 2006, has been the cause of considerable discussion among space professionals. The policy statement is a broad umbrella that lays out the nation's objectives in space, from science to commercial to national security and intelligence. The policy appears to support numerous national space objectives that were contained in the previous (1996) policy statement, of the Clinton administration. It also articulates in one location many of the pronouncements on space activities that have been promulgated since 2001. Some of the unhappiness expressed in editorial comments would seem to occur because words such as "Mars" and "Moon" do not appear explicitly. At the same time, neither do the words "space weather."

Lanzerotti, Louis J.

2006-12-01

247

Space weather: European Space Agency perspectives  

NASA Astrophysics Data System (ADS)

Spacecraft and payloads have become steadily more sophisticated and therefore more susceptible to space weather effects. ESA has long been active in applying models and tools to the problems associated with such effects on its spacecraft. In parallel, ESA and European agencies have built a highly successful solar-terrestrial physics capability. ESA is now investigating the marriage of these technological and scientific capabilities to address perceived user needs for space weather products and services. Two major ESA-sponsored studies are laying the groundwork for a possible operational European space weather service. The wide-ranging activities of ESA in the Space Weather/Space Environment domain are summarized and recent important examples of space weather concerns given.

Daly, E. J.; Hilgers, A.

248

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

249

Johnson Space Center  

NASA Astrophysics Data System (ADS)

The Johnson Space Center (JSC) in Houston is NASA's lead center for the space shuttle and the International Space Station programs and for biomedical research. Areas of study include Earth sciences and solar system exploration, astromaterials and space medicine. About 14 000 people, including 3000 civil servants, work at JSC....

Murdin, P.

2000-11-01

250

Space Spider Crane.  

National Technical Information Service (NTIS)

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 a...

I. O. Macconochie J. E. Pennington C. F. Bryan M. M. Mikulas R. L. Kinkead

1986-01-01

251

Perspectives on Space Operations  

Microsoft Academic Search

The debate over military uses of space generally and the weaponization of space in particular is as old as the space age itself. Most recently this debate has been re-invigorated in Canada within the context of Ballistic Missile Defence. This article provides an overview of the legal framework governing the use of force in space, concluding that military activity including,

Patrick K. Gleeson

2007-01-01

252

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 (Newtonâs 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

253

On complex Douglas spaces  

NASA Astrophysics Data System (ADS)

In this paper we survey projective curvature invariants of Douglas type and use these to give some generalizations for the notion of a complex Berwald space. Various descriptions of complex Douglas spaces are given in relation to other special classes of complex Finsler spaces. This study was performed from the viewpoint of the equations of a complex geodesic curve. Complex Randers spaces offer examples of complex Douglas spaces.

Aldea, Nicoleta; Munteanu, Gheorghe

2013-04-01

254

Noncommutative spherically symmetric spaces  

SciTech Connect

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

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

2011-01-15

255

Affordable Space Tourism: SpaceStationSim.  

National Technical Information Service (NTIS)

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

2006-01-01

256

Man in Space, Space in the Seventies.  

ERIC Educational Resources Information Center

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

Froehlich, Walter

257

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

258

Space technology aspects of space science instrumentation  

NASA Astrophysics Data System (ADS)

The United Kingdom (UK) Space Science Research is focused largely upon the work of the university community. The Science and Engineering Research Council, in conjuction with the British National Space Centre, coordinates central support in terms of science, technology and management at its Rutherford Appleton Laboratory. This paper gives an indication of the broad spread of UK activities.

Turner, R. F.

259

SpaceTech—Postgraduate space education  

NASA Astrophysics Data System (ADS)

SpaceTech is a postgraduate program geared primarily for mid-career space professionals seeking to gain or improve their expertise in space systems engineering and in business engineering. SpaceTech provides a lifelong impact on its participants by broadening their capabilities, encouraging systematic "end-to-end" thinking and preparing them for any technical or business-related engineering challenges they may encounter. This flexible 1-year program offers high competency gain and increased business skills. It is held in attractive locations in a flexible, multi-cultural environment. SpaceTech is a highly effective master's program certified by the esteemed Technical University of Delft (TUD), Netherlands. SpaceTech provides expert instructors who place no barriers between themselves and participants. The program combines innovative and flexible new approaches with time-tested methods to give participants the skills required for future missions and new business, while allowing participants to meet their work commitments at the same time as they study for their master's degree. The SpaceTech program is conducted in separate sessions, generally each of 2-week duration, separated by periods of some 6-8 weeks, during which time participants may return to their normal jobs. It also includes introductory online course material that the participants can study at their leisure. The first session is held at the TUD, with subsequent sessions held at strategic space agency locations. By participating at two or more of these sessions, attendees can earn certificates of satisfactory completion from TU Delft. By participating in all of the sessions, as well as taking part in the companion Central Case Project (CCP), participants earn an accredited and highly respected master's degree in Space Systems Engineering from the TUD. Seven distinct SpaceTech modules are provided during these sessions: Space Mission Analysis and Design, Systems Engineering, Business Engineering, Interpersonal Skills, Telecommunications, Earth Observation and Navigation. A group CCP, a major asset of this unique program, is a focused project, aimed at the formation of a credible virtual commercial space-related business. Participants exercise space systems engineering fundamentals as well as marketing and business engineering tools, with the goal of creating a financially viable business opportunity. They then present the result, in the form of an unsolicited proposal to potential investors, as well as a varied group of engineers, managers and executives from the space community. During the CCP, participants learn the ties between mission and system design and the potential return to investors. They develop an instinct for the technical concepts and which of the parameters to adjust to make their newly conceived business more effective and profitable.

de Bruijn, Ferdi J.; Ashford, Edward W.; Larson, Wiley J.

2008-07-01

260

Section 2: The Space of Media Space  

NASA Astrophysics Data System (ADS)

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

Harrison, Steve

261

Space Weather FX  

NSDL National Science Digital Library

Space Weather FX is a vodcast (video podcast) series that explores the science of space weather and how it can impact our every day lives. Episodes include Space Weather and its Effects, Connecting the Sun and Earth, When Space Weather Attacks, Stratospheric Sudden Warming, A Tour of Haystack's Radars, GPS and Space Weather, It Came from the Sun, and The Big Picture. The site also contain links to space weather information and educational materials. The episodes will run on one of four free video players.

262

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Wash spaces; toilet spaces; and shower spaces. 108.205...Accommodation Spaces § 108.205 Wash spaces; toilet spaces; and shower spaces. (a) For... (1) âPrivate facilityâ means a toilet, washing, or shower space that...

2012-10-01

263

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

264

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.

265

Traveling Space Museum  

NASA Video Gallery

In an effort to inspire and motivate the next generation of space explorers, NASA’s Ames Research Center teamed up with the Traveling Space Museum to teach students the way astronauts are taught…by doing.

Cathy Weselby

2010-09-16

266

Space Day 2000.  

ERIC Educational Resources Information Center

Introduces three design challenges for fourth, fifth, and sixth grade students created by the Challenger Center for Space Science Education. Presents information on Space Day and the National Classroom and provides Internet site addresses. (YDS)

Winslow, Joyce

2000-01-01

267

European Space Agency (ESA)  

NASA Astrophysics Data System (ADS)

An international organization whose task is `to provide for and to promote, for exclusively peaceful purposes, cooperation among European states in space research and technology and their space applications'....

Murdin, P.

2000-11-01

268

Space Flute Duet  

NASA Video Gallery

Harmony reaches new heights as NASA Astronaut Cady Coleman, circling Earth aboard the International Space Station, and musician Ian Anderson, founder of the rock band Jethro Tull, join together for the first space-Earth duet.

Gerald T Wright

2011-04-08

269

Open Space Plan.  

National Technical Information Service (NTIS)

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

1973-01-01

270

Huntsville, Alabama From Space  

NASA Website

International Space Station - captures an image of her hometown. ISERV was designed and built at NASA's Marshall Space Flight Center in Huntsville, Ala. ISERV provides useful images for disaster monitoring and assessment and environmental ...

271

Goddard Space Flight Center  

NASA Astrophysics Data System (ADS)

The Goddard Space Flight Center (GSFC), in Greenbelt, MD, named for Dr Robert H Goddard, a pioneer in rocket research, was established in 1959. Since that time, GSFC has played a major role in space and Earth science....

Murdin, P.

2000-11-01

272

Giving women their space  

Microsoft Academic Search

In an attempt to spark greater interest in space sciences among high school girls, the Harvard-Smithsonian Center for Astrophysics has been distributing a booklet entitled ``Space for Women: Perspectives on Careers in Science.'' The 20-page color booklet offers advice and encouragement to young women interested in space physics, astronomy, and other space-related fields. More than 10,000 copies have already been

Michael Carlowicz

1996-01-01

273

Giving women their space  

NASA Astrophysics Data System (ADS)

In an attempt to spark greater interest in space sciences among high school girls, the Harvard-Smithsonian Center for Astrophysics has been distributing a booklet entitled “Space for Women: Perspectives on Careers in Science.” The 20-page color booklet offers advice and encouragement to young women interested in space physics, astronomy, and other space-related fields. More than 10,000 copies have already been distributed to students, teachers, and career counselors.

Carlowicz, Michael

274

Japanese space program  

NASA Astrophysics Data System (ADS)

The organization and budget of Japanese space activities is outlined. There are two major performers: NASDA (National Space Development Agency) and ISAS (Institute of Space and Astronautical Sciences). The budget is roughly 1 billion dollars/year (1/10 of NASDA's budget), 70% goes to NASA, and 10% to ISAS. NASDA's space development programs, launch vehicles, NASDA's satellite programs, HOPE (H-2 Orbiting Plane) Project, scientific satellites of ISAS and NASDA's major facilities are described.

Morino, Yoshiki

1993-06-01

275

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

276

My Place, My Space  

ERIC Educational Resources Information Center

|Five- and six-year-olds know a lot about their own homes. Besides school, home is probably where they spend most of their time. But have they ever really thought about their space? Using students' knowledge of their current space will help them design new spaces and think about all the areas that surround them. In this project, students design…

Kostal, Heather

2011-01-01

277

Dependent Probability Spaces  

ERIC Educational Resources Information Center

|The mathematical model used to describe independence between two events in probability has a non-intuitive consequence called dependent spaces. The paper begins with a very brief history of the development of probability, then defines dependent spaces, and reviews what is known about finite spaces with uniform probability. The study of finite…

Edwards, William F.; Shiflett, Ray C.; Shultz, Harris

2008-01-01

278

Hydrogen Masers for Space.  

National Technical Information Service (NTIS)

A program for the design and testing of atomic hydrogen (H) masers for general use in space and methods for high precision space to Earth time and frequency comparisons are described. Because of the similarity of the space masers' basic components to thos...

R. F. C. Vessot E. M. Mattison G. U. Nystrom L. M. Coyle R. Decher

1992-01-01

279

Brazilian Space Weather Program  

Microsoft Academic Search

A space weather program is being initiated at the Brazilian National Institute for Space Research (INPE) to study events from their initiation on the sun to their impacts on the earth, including their effects on space-based and ground-based technological systems. The program is built on existing capabilities at INPE, which include scientists with a long tradition and excellence in the

Antonio Padilha; Hisao Takahashi; Eurico de Paula; Hanumant Sawant; Haroldo de Campos Velho; Icaro Vitorello; Joaquim Costa; Jonas Souza; José Cecatto; Odim Mendes; Walter Demétrio Gonzalez Alarcon

2008-01-01

280

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

281

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

282

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

283

Space law conference 2001  

Microsoft Academic Search

Many eminent space lawyers gathered in Singapore to attend the first space law conference to be held in South East Asia. Topics for discussion—which included commercialization of space activities and its effect on the needs of developing countries, and the legal issues of expanding communications and navigation satellite services—were of particular interest to the region. This report summarizes the presentations

Tanja Masson-Zwaan

2001-01-01

284

Introduction to Space Climate  

Microsoft Academic Search

Space Climate” is a relatively new scientific concept, which combines a number of disciplines in space and atmospheric sciences under the common aim to better understand the long-term changes in the Sun, heliosphere and in the near-Earth environment. In this brief summary we define the contents and aims of Space Climate. We also review some recent findings that are discussed

K. Mursula; I. G. Usoskin; G. Maris

2007-01-01

285

Representations for space planning  

Microsoft Academic Search

Problems involving the arrangement of objects in two- or three-space where the objective function primarily consists of derivatives of the distance between objects or their arrangement are called space planning problems. The representational requirements for this problem area are defined and compared with current computer graphic languages. Four alternative data structures that allow automated space planning are described and compared.

Charles M. Eastman

1970-01-01

286

Dependent Probability Spaces  

ERIC Educational Resources Information Center

The mathematical model used to describe independence between two events in probability has a non-intuitive consequence called dependent spaces. The paper begins with a very brief history of the development of probability, then defines dependent spaces, and reviews what is known about finite spaces with uniform probability. The study of finite…

Edwards, William F.; Shiflett, Ray C.; Shultz, Harris

2008-01-01

287

Space weather risk  

Microsoft Academic Search

The importance of space weather to society is in a continuous increase since we are more and more dependent on reliable spaceborne and ground-based technological systems. Physical processes involved in space weather constitute a complicated chain from the Sun to the Earth's surface, so the management of space weather risks requires expertise in many disciplines of science and technology. In

Risto Pirjola; Kirsti Kauristie; Hanna Lappalainen; Ari Viljanen; Antti Pulkkinen

2005-01-01

288

Hazy Spaces, Tangent Spaces, Manifolds and Groups.  

National Technical Information Service (NTIS)

The results on hazy spaces and the developments leading to hazy manifolds and groups are summarized. Proofs have appeared elsewhere so here examples are considered and some motivation for definitions and constructions in the theorems is analyzed. It is sh...

C. T. J. Dodson

1977-01-01

289

Space Science Using Columbus: Manned Space Science.  

National Technical Information Service (NTIS)

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

H. Olthof

1988-01-01

290

The Ninth National Space Symposium  

NASA Astrophysics Data System (ADS)

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

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

291

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.

292

Pharmacotherapeutics in space.  

PubMed

The goal of pharmacology research the Johnson Space Center has been to identify safe and effective diagnostic and pharmacological intervention products, procedures, and strategies in support of successful space medical operations. The specific objectives of research are to identify physiologic, pharmacokinetic, and pharmacodynamic changes in space; to develop simple, reliable, non-invasive, safe and effective acute and sustained-release dosage forms and regimens for pharmacological interventions in space; and to create and maintain a comprehensive space PK-PD and therapeutics database. Highlights of the pharmacology research reviewed include development and validation of methods for pharmacologic research, in-flight pharmacokinetics, and alternative drug delivery methods. PMID:11543005

Putcha, L

1999-07-01

293

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

294

Space physics exhibits underway  

NASA Astrophysics Data System (ADS)

AGU is planning a new space science exhibit for the Smithsonian Institution's National Air and Space Museum in Washington that will help visitors come to an understanding of space science as a comprehensive, interdisciplinary, and exciting field. The title of the exhibit is “Electric Space: Our Earth-Sun Environment.” The exhibit's five modules will include demonstrations of the effects of particle and field radiation on humans and satellites in space and on human technology on the ground. The project also includes a larger traveling version that will visit science and technology centers throughout the United States. The first exhibit is planned to open at the Air and Space Museum in late summer or early fall 1992, in time for International Space Year activities; the traveling exhibit will begin touring in early 1993.

DeVito, M. Catherine

295

Austrian Space Agency  

NSDL National Science Digital Library

"The Austrian Space Agency, ASA, established by the Federal authorities in Vienna in 1972, serves as a focal point for the co-ordination of space activities in Austria and is the Austrian link to international space activities." The website offers summaries of the organization's past and present research activities with the ESA Space Science Programme and the International Mars Exploration Working Group (IMEWG). Users can find inspiring biographies of nine Austrian space pioneers as well as information on the latest news and events. While the English version of the organization's work in nanotechnology and aeronautics is not yet available, the Space link provides materials on many educational opportunities including details of the Alpbach Summer School and information on courses in space law.

296

Ion chemistry in space.  

PubMed

We review the gas-phase chemistry in extraterrestrial space that is driven by reactions with atomic and molecular ions. Ions are ubiquitous in space and are potentially responsible for the formation of increasingly complex interstellar molecules. Until recently, positively charged atoms and molecules were the only ions known in space; however, this situation has changed with the discovery of various molecular anions. This review covers not only the observation, distribution and reactions of ions in space, but also laboratory-based experimental and theoretical methods for studying these ions. Recent results from space-based instruments, such as those on the Cassini-Huygens space mission and the Herschel Space Observatory, are highlighted. PMID:22790651

Larsson, M; Geppert, W D; Nyman, G

2012-05-23

297

China's Space Policy  

NASA Astrophysics Data System (ADS)

The scope of mankind's explorations has expanded from the land to the ocean, from the ocean to the air and from the air to outer space. Space technology, which emerged in the 1950's, opened up a new era of human exploration of outer space. Having developed rapidly for the last half century, mankind's activities in space have come a long way, greatly promoted social progress and had profound and far-reaching effects. Space technology is the field of high technology that has exerted the most profound influence on modern society. The continuous development and application of space technology has become an important endeavor in the modernization drives of countries all over the world. After the People's Republic of China was founded in 1949, China carried out space activities on its own. It succeed in developing and launching its first man-made satellite in 1970. China has made notable achievements and now ranks among the world's most advanced countries in some important fields of space technology. In the 21st century, China will continue to promote the development of its space industry in accordance with its national conditions, and make due contributions to the peaceful use of outer space and to the civilization and progress of all the human beings. At the turn of the century, it is important to give a brief introduction to the aims and principles, the present situation, future development plans and international co-operation concerning China's space activities. This paper covers the following aspects: development strategy, and held that the exploration and utilization of outer space should be for peaceful purposes and for the benefit of all human beings. China is drafting a space development strategy for the 21st century according to the actual demands and long-term targets of national development and to encourage growth of the space industry.

Wen, Y.

2002-01-01

298

Making space law relevant to basic space science in the commercial space age  

Microsoft Academic Search

Space science has been at the heart of humanity's activity in space, a fact reflected in the body of space law set up to regulate such activity. The increase in commercial utilisation of space may threaten the conduct of space science; reform of space law, however, could alleviate this situation. Using the examples of radio and light interference, and space

Sriram Swaminathan

2005-01-01

299

The Space Weather Reanalysis  

NASA Astrophysics Data System (ADS)

The objective of this project is to generate a complete 11 year space weather representation using physically consistent data-driven space weather models. The project will create a consistent, integrated historical record of the near Earth space environment by coupling observational data from space environmental monitoring systems archived at NGDC with data-driven, physically based numerical models. The resulting product will be an enhanced look at the space environment on consistent grids, time resolution, coordinate systems and containing key fields allowing an interested user to quickly and easily incorporate the impact of the near-Earth space climate in environmentally sensitive models. Currently there are no easily accessible long term climate archives available for the space-weather environment. Just as with terrestrial weather it is crucial to understand both daily weather forecasts as well as long term climate changes, so this project will demonstrate the ability to generate a meaningful and physically derived space weather climatology. The results of this project strongly support the DOD's Environmental Scenario Generator (ESG) project. The ESG project provides tools for intellegent data mining, classification and event detection which could be applied to a historical space-weather database. The two projects together provide a suite of tools for the user interested in modeling the effect of the near-earth space environment. We will present results and methodologies developed during the first two years of effort in the project.

Kihn, E. A.; Ridley, A. J.; Zhizhin, M.

2002-12-01

300

Pappus in optical space.  

PubMed

Optical space differs from physical space. The structure of optical space has generally been assumed to be metrical. In contradistinction, we do not assume any metric, but only incidence relations (i.e., we assume that optical points and lines exist and that two points define a unique line, and two lines a unique point). (The incidence relations have generally been assumed implicitly by earlier authors.) The condition that makes such an incidence structure into a projective space is the Pappus condition. The Pappus condition describes a projective relation between three collinear triples of points, whose validity can--in principle--be verified empirically. The Pappus condition is a necessary condition for optical space to be a homogeneous space (Lobatchevski hyperbolic or Riemann elliptic space) as assumed by, for example, the well-known Luneburg theory. We test the Pappus condition in a full-cue situation (open field, broad daylight, distances of up to 20 m, visual fields of up to 160 degrees diameter). We found that although optical space is definitely not veridical, even under full-cue conditions, violations of the Pappus condition are the exception. Apparently optical space is not totally different from a homogeneous space, although it is in no way close to Euclidean. PMID:12049279

Koenderink, Jan J; van Doorn, Andrea J; Kappers, Astrid M L; Todd, James T

2002-04-01

301

Space Resources Roundtable 2  

NASA Astrophysics Data System (ADS)

Contents include following: Developing Technologies for Space Resource Utilization - Concept for a Planetary Engineering Research Institute. Results of a Conceptual Systems Analysis of Systems for 200 m Deep Sampling of the Martian Subsurface. The Role of Near-Earth Asteroids in Long-Term Platinum Supply. Core Drilling for Extra-Terrestrial Mining. Recommendations by the "LSP and Manufacturing" Group to the NSF-NASA Workshop on Autonomous Construction and Manufacturing for Space Electrical Power Systems. Plasma Processing of Lunar and Planetary Materials. Percussive Force Magnitude in Permafrost. Summary of the Issues Regarding the Martian Subsurface Explorer. A Costing Strategy for Manufacturing in Orbit Using Extraterrestrial Resources. Mine Planning for Asteroid Orebodies. Organic-based Dissolution of Silicates: A New Approach to Element Extraction from LunarRegohth. Historic Frontier Processes Active in Future Space-based Mineral Extraction. The Near-Earth Space Surveillance (NIESS) Mission: Discovery, Tracking, and Characterization of Asteroids, Comets, and Artificial Satellites with a microsatellite. Privatized Space Resource Property Ownership. The Fabrication of Silicon Solar Cells on the Moon Using In-Situ Resources. A New Strategy for Exploration Technology Development: The Human Exploration and Development of Space (HEDS) Exploratiori/Commercialization Technology Initiative. Space Resources for Space Tourism. Recovery of Volatiles from the Moon and Associated Issues. Preliminary Analysis of a Small Robot for Martian Regolith Excavation. The Registration of Space-based Property. Continuous Processing with Mars Gases. Drilling and Logging in Space; An Oil-Well Perspective. LORPEX for Power Surges: Drilling, Rock Crushing. An End-To-End Near-Earth Asteroid Resource Exploitation Plan. An Engineering and Cost Model for Human Space Settlement Architectures: Focus on Space Hotels and Moon/Mars Exploration. The Development and Realization of a Silicon-60-based Economy in CisLunar Space. Our Lunar Destiny: Creating a Lunar Economy. Cost-Effective Approaches to Lunar Passenger Transportation. Lunar Mineral Resources: Extraction and Application. Space Resources Development - The Link Between Human Exploration and the Long-term Commercialization of Space. Toward a More Comprehensive Evaluation of Space Information. Development of Metal Casting Molds by Sol-Gel Technology Using Planetary Resources. A New Concept in Planetary Exploration: ISRU with Power Bursts. Bold Space Ventures Require Fervent Public Support. Hot-pressed Iron from Lunar Soil. The Lunar Dust Problem: A Possible Remedy. Considerations on Use of Lunar Regolith in Lunar Constructions. Experimental Study on Water Production by Hydrogen Reduction of Lunar Soil Simulant in a Fixed Bed Reactor.

Ignatiev, A.

2000-01-01

302

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

303

SSC Space Physics Tutorial  

NSDL National Science Digital Library

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

2000-01-01

304

Masticator Space Neoplasms  

Microsoft Academic Search

The masticator space (MS) is a deep facial space delineated by a splitting of the deep cervical fascia which encloses the\\u000a four muscles of mastication: the medial and the lateral pterygoid, the masseter, and the temporalis muscles – hence the denomination\\u000a of “masticator space” (Harnsberger 1995; Mukherji and Chong 2004). The MS also contains the ramus and posterior body of

Thierry P. Duprez; Emmanuel E. Coche

305

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

306

Space Group Symmetry  

NSDL National Science Digital Library

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

307

Space Weather Media Viewer  

NSDL National Science Digital Library

This is version 3 of the space Weather Media Viewer, created to work with the space Weather Action Center to see near-real time data and to provide additional images and resources available for educational use. It features easy downloads that can also be added to news reports and space weather reports. It was designed for ease in adding any media (videos, images) data.

2011-01-01

308

Axes in Outer Space  

Microsoft Academic Search

We develop a notion of axis in the Culler--Vogtmann outer space X_r of a finite rank free group F_r, with respect to the action of a nongeometric, fully irreducible outer automorphism phi. Unlike the situation of a loxodromic isometry acting on hyperbolic space, or a pseudo-Anosov mapping class acting on Teichmuller space, X_r has no natural metric, and phi seems

Michael Handel; Lee Mosher

2006-01-01

309

Space Weather: Welcome, SEC  

NSDL National Science Digital Library

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

Spangler, Tim

2005-01-11

310

Basics of Space Flight  

NSDL National Science Digital Library

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

311

Space as a Resource  

Microsoft Academic Search

\\u000a In this assay, we aim at defending the hypothesis that physically spoken sheer “empty” space in itself without any other commodities\\u000a has the function of resource for plant life. Definitions of space, niche, and resource are examined. We consider competition\\u000a for resources and space occupation and exploitation above ground, where light is often a decisive limiting factor. Steady-state\\u000a and dynamic

Thorsten E. E. Grams; Ulrich Lüttge

312

PQLI Design Space  

Microsoft Academic Search

This paper describes progress made by the Design Space Task Team within the ISPE Product Quality Lifecycle Implementation\\u000a (PQLI) initiative. It is intended to provide approaches to the rational development of Design Space, as well as background\\u000a on Design Space, its historical origins and how it fits within the wider PQLI initiative. The focus of this paper is on the

John Lepore; James Spavins

2008-01-01

313

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

314

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.

315

Radiation protection in space.  

PubMed

Radiation environment, basic concepts of radiation protection, and specific aspects of the space radiation field are reviewed. The discussion of physico-chemical and subcellular radiation effects includes mechanisms of radiation action and cellular consequences. The discussion of radiobiological effects includes unique aspects of HZE particle effects, space flight findings, terrestrial findings, analysis of somatic radiation effects and effects on critical organs, and early and delayed effects. Other topics include the impact of the space flight environment, measurement of radiation exposure, establishing radiation protection limits, limitations in establishing space-based radiation exposure limits, radiation protection measures, and recommendations. PMID:11541474

Reitz, G; Facius, R; Sandler, H

316

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.

317

Loops in twistor space  

SciTech Connect

We elucidate the one-loop twistor-space structure corresponding to momentum-space maximally helicity-violating diagrams. We also discuss the infrared divergences, and argue that only a limited set of maximally helicity-violating diagrams contain them. We show how to introduce a twistor-space regulator corresponding to dimensional regularization for the infrared-divergent diagrams. We also evaluate explicitly the 'holomorphic anomaly' pointed out by Cachazo, Svrcek, and Witten, and use the result to define modified differential operators which can be used to probe the twistor-space structure of one-loop amplitudes.

Bena, Iosif; Bern, Zvi; Kosower, David A.; Roiban, Radu [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States); Service de Physique Theorique, CEA-Saclay F-91191 Gif-sur-Yvette cedex (France); Department of Physics, University of California, Santa Barbara, California 93106 (United States) and Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2005-05-15

318

Space weather in Japan  

NASA Astrophysics Data System (ADS)

In Japan, Communications Research Laboratory engages in operational space environment information service as National Forecasting Center and Regional Warning Center of ISES. Data of local observation and data collected via internet from domestic and foreign institute are used for daily operational forecast. Fundamental research on space weather issue has been carried out at several institutes and university, including STE Laboratory and NASDA. In this presentation, overview of current space weather forecast operation and system for information outreach in Japan will be presented. Current and future observation program from ground-base and space will be also briefly reviewed.

Akioka, M.

319

Space weather in Japan  

NASA Astrophysics Data System (ADS)

In Japan, Communications Research Laboratory engages in operational space environment information services as National Forecasting Center and Regional Warning Center of ISES. Data from local observations and data collected via internet from domestic and foreign institutes are used for the daily operational forecast. Fundamental research on space weather issues has been carried out at several institutes and universities, including STE Laboratory and NASDA. In this presentation, an overview of current space weather forecast operations and a system for information outreach in Japan will be presented. Current and future observation programs from ground-base and space will be also briefly reviewed.

Akioka, M.; Ishibashi, H.; Kikuchi, T.; Sagawa, E.; Nagatsuma, T.

320

Multimegawatt space power reactors  

NASA Astrophysics Data System (ADS)

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

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

321

Space Flight Now  

NSDL National Science Digital Library

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

322

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

323

Space Resource Roundtable Rationale  

NASA Astrophysics Data System (ADS)

Recent progress in the U.S. Space Program has renewed interest in space resource issues. The Lunar Prospector mission conducted in NASA's Discovery Program has yielded interesting new insights into lunar resource issues, particularly the possibility that water is concentrated in cold traps at the lunar poles. This finding has not yet triggered a new program of lunar exploration or development, however it opens the possibility that new Discovery Missions might be viable. Several asteroid missions are underway or under development and a mission to return samples from the Mars satellite, Phobos, is being developed. These exploration missions are oriented toward scientific analysis, not resource development and utilization, but can provide additional insight into the possibilities for mining asteroids. The Mars Surveyor program now includes experiments on the 2001 lander that are directly applicable to developing propellants from the atmosphere of Mars, and the program has solicited proposals for the 2003/2005 missions in the area of resource utilization. These are aimed at the eventual human exploration of Mars. The beginning of construction of the International Space Station has awakened interest in follow-on programs of human exploration, and NASA is once more studying the human exploration of Moon, Mars and asteroids. Resource utilization will be included as objectives by some of these human exploration programs. At the same time, research and technology development programs in NASA such as the Microgravity Materials Science Program and the Cross-Enterprise Technology Development Program are including resource utilization as a valid area for study. Several major development areas that could utilize space resources, such as space tourism and solar power satellite programs, are actively under study. NASA's interests in space resource development largely are associated with NASA missions rather than the economic development of resources for industrial processes. That is why there is an emphasis in NASA programs on propellant production on Mars - NASA plans missions to Mars, so could make use of those propellants. For other types of applications, however, it will be up to market forces to define the materials and products needed and develop the technologies for extracting them from space resources. Some leading candidates among the potential products from space resources are propellants for other space activities, water from the Moon for use in space, silicon for photovoltaic energy collection in space, and, eventually, He-3 from the Moon for fusion energy production. As the capabilities for manufacturing materials in space are opened up by research aboard the International Space Station, new opportunities for utilization of space resources may emerge. Whereas current research emphasizes increasing knowledge, one program objective should be the development of industrial production techniques for space. These will be based on the development of value-added processing in space, where materials are brought to the space facility, processed there, and returned to Earth. If enough such space processing is developed that the materials transportation requirements are measured in the hundreds of tons a year level, opportunities for substituting lunar materials may develop. The fundamental message is that it is not possible to develop space resources in a vacuum. One must have three things: a recoverable resource, technology to recover it, and a customer. Of these, the customer probably is the most important. All three must be integrated in a space resource program. That is what the Space Resource Roundtable, initiated with this meeting, will bring together.

Duke, Michael

1999-01-01

324

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

325

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

326

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

327

Learning Spaces: A Tutorial  

ERIC Educational Resources Information Center

|The opportunity to design a learning space does not come along often. Usually, it involves the construction of a new building or the complete remodel of an old one, and both of these require a lot of money. Smaller projects, such as renovation of a single room or a defined space, can be the best way to test ideas and establish a model for…

MacPhee, Larry

2009-01-01

328

Space Weapons Earth Wars.  

National Technical Information Service (NTIS)

Space weapons for terrestrial conflict have been the subject of intense debate twice in the modern history of space. The first time, at the beginning of the Cold War, was over the possibility of bombardment satellites carrying nuclear weapons. The second ...

B. Preston C. Shipbaugh D. J. Johnson M. Miller S. J. Edwards

2002-01-01

329

Commercialization of space activities  

Microsoft Academic Search

Commercialization of space activities requires a legal framework for private investors and entrepreneurs in order to promote and develop this sector of industry into a fully-fledged commercial enterprise. Apart from the already existing international public legal framework of space law, rules should be created to provide a level playing field for all interested parties. These rules should point to transparency

Hanneke L. van Traa-Engelman

1996-01-01

330

Geometry of face space  

Microsoft Academic Search

The geometrical character of face space is investigated, and is analyzed within the framework of eigenface decompositions. To deal with the sparse data problem, which occurs when not enough data is present to fill the space, we construct and test a range of probabilistic models. A key tool in this investigation is the decomposition of the eigenfaces representation of face

Lawrence Sirovich; Marsha Meytlis

331

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

332

NASA Facts, Space Shuttle.  

ERIC Educational Resources Information Center

This newsletter from the National Aeronautics and Space Administration (NASA) contains a description of the purposes and potentials of the Space Shuttle craft. The illustrated document explains some of the uses for which the shuttle is designed; how the shuttle will be launched from earth, carry out its mission, and land again on earth; and what a…

National Aeronautics and Space Administration, Washington, DC. Educational Programs Div.

333

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

334

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.

335

Space Elevator: Stability  

Microsoft Academic Search

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

Lubos Perek

2008-01-01

336

Law in Outer Space.  

ERIC Educational Resources Information Center

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

Schmidt, William G.

1997-01-01

337

Space charge stopband correction  

SciTech Connect

It is speculated that the space charge effect cause beam emittance growth through the resonant envelope oscillation. Based on this theory, we propose an approach, called space charge stopband correction, to reduce such emittance growth by compensation of the half-integer stopband width of the resonant oscillation. It is illustrated with the Fermilab Booster model.

Huang, Xiaobiao; /Fermilab /Indiana U.; Lee, S.Y.; /Indiana U.

2005-09-01

338

An Event Spacing Experiment  

Microsoft Academic Search

Events in self-timed rings can propagate evenly spaced or as bursts. By studying these phenomena, we obtain a better understanding of the underlying dynamics of self-timed pipelines, which is a necessary precursor to utilizing these dynamics to obtain higher performance. We show that standard bounded delay models are inadequate to discriminate between bursting and evenly spaced behaviours and show that

Mark R. Greenstreet; Anthony Winstanley; Aurelien Garivier

2002-01-01

339

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.

340

Law in Outer Space.  

ERIC Educational Resources Information Center

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

Schmidt, William G.

1997-01-01

341

Wallace Stevens: Redefining space  

Microsoft Academic Search

In this dissertation, I examine the manner in which Stevens redefines space to depict the mesh of imagination and material reality. After he establishes a scene or setting of external reality, which I term base reality, Stevens immediately redefines that space into something that imaginatively transcends a confining frame. Base reality no longer exists as itself since it is transformed

Cathleen A Hannigan

2003-01-01

342

Shelf Space Projection Survey.  

ERIC Educational Resources Information Center

|This study of the present and projected space requirements for book and periodical collections of the State University of New York Libraries, excluding community colleges, is based on the assumptions that the annual rate of acquisitions and the present space dedicated to book and periodical shelving remain constant. The survey questionnaire…

Wittenborg, Karen; Camp, John F.

343

Problems of space chemistry  

Microsoft Academic Search

The main problems of space chemistry are examined, including the origin and abundance of chemical elements, their migration to different regions of the universe, the formation of the chemical composition of cosmic bodies, and the chemical evolution of the solar system and the origin of life. Based on current astrophysical and space-chemical data, the main stages of the evolution of

Georgii V. Voitkevich

1987-01-01

344

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.

345

A Search Space Toolkit  

Microsoft Academic Search

The Search Space Toolkit (SST) is a suite of tools for investigating the properties of the continuous search spaces which arise in designing complex engineering artifacts whose evaluation requires significant computation by a numerical simulator. SST has been developed as part of NDA, a computational environment for (semi-)automated design of jet engine exhaust nozzles for supersonic aircraft, which was developed

Andrew Gelsey; Don Smith

1995-01-01

346

Pulse combustion space heater  

Microsoft Academic Search

This patent describes a pulse combustion space heater for heating air in a space to be temperature conditioned. It comprises: a cabinet having exterior walls providing a cabinet volume for enclosing and supporting the heater, interior housing means located within the cabinet volume including walls providing a substantially closed heat transfer chamber having inlet and outlet openings through which air

W. H. Thrasher; C. M. Pavlik; L. Moon

1990-01-01

347

Underground space: another resource  

Microsoft Academic Search

The use of underground space for buildings in order to save land costs and energy consumption is discussed. The use and design of underground buildings for the storage of fuels and ammunitions, for hospitals, schools, and office space are discussed. The costs of heating and cooling underground buildings and aboveground buildings are compared. It is concluded that underground installations are

1977-01-01

348

International Space Cooperation.  

National Technical Information Service (NTIS)

France has long been the U.S.'s closest partner in space exploration. For example, NASA has more active space cooperation agreements with France than any other country. NASA's first overseas representative was deployed to Paris in 1964. This position has ...

M. D. Griffin

2008-01-01

349

Open Space. Conservation Element.  

National Technical Information Service (NTIS)

The report documents discussions of the Santa Rosa Open Space Committee held during this year on the issues of open space and conservation. Types of existing open land are identified and analyzed in terms of: the physical, cultural, and historical factors...

1972-01-01

350

The Space Interferometry Mission  

Microsoft Academic Search

The Space Interferometry Mission (SIM) is the next major space mission in NASA's Origins program after SIRTF. The SIM architecture uses three Michelson interferometers in low-earth orbit to provide 4 microarcsecond precision absolute astrometric measurements on approx. 40,000 stars. SIM will also provide synthesis imaging in the visible waveband to a resolution of 10 milliarcsecond, and interferometric nulling to a

Stephen C. Unwin

1998-01-01

351

Water and Space  

Microsoft Academic Search

In a book about water on Earth, it is perhaps unusual to describe the search for water in outer space. When we think of water, we think of the blood of all life on Earth. Space, on the other hand, is a vast, unimaginably empty vacuum, dotted with stars and inher- ently inimical to life on Earth. Why would we

Elizabeth L. Chalecki

352

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

353

European Space Agency (ESA)  

NSDL National Science Digital Library

The ESA homepage provides information on the ESA's telecommunications, navigations, Earth observations, human spaceflight missions, launches, space science, technology, industry, space operations, technical and quality management, and television. The site also contains a multimedia gallery, press releases, and an educational page for kids.

2005-06-13

354

Cryocoolers for Space  

Microsoft Academic Search

Many of the detectors for space telescopes require cooling to increase sensitivity and reduce thermal noise. For space applications, such cooling requires reliable, long-life coolers that are relatively compact and light weight and have low vibration. We have developed or are developing coolers that meet these requirements over a wide range of temperatures. These include pulse tube coolers cooling from

Kittel Peter; Pat Roach; Jeff Feller; Ali Kashani; Ben Helvensteijn

2002-01-01

355

Cryocoolers for Space.  

National Technical Information Service (NTIS)

This paper presents Cryocoolers for Space in viewgraph form. The topics include: (1) U.S. Cryocoolers for 4 to 6 Kelvin; (2) Turbo Brayton Cryocooler-Features; (3) HST/NICMOS (Hubble Space Telescope/Near Infrared Camera and Multiobject Spectrometer) 75 Ke...

S. Castles

2000-01-01

356

Space Flight 101.  

National Technical Information Service (NTIS)

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

J. Bacon

2006-01-01

357

ISS Update: Space Nutrition  

NASA Video Gallery

NASA Public Affairs Officer Amiko Kauderer interviews Scott M. Smith, NASA Nutritionist, about nutrition experiments taking place aboard the International Space Station. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #askStation. For the latest news about the space station, visit http://www.nasa.gov/station.

Russell Todd D

2012-02-10

358

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…

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

359

Asymmetry in media spaces  

Microsoft Academic Search

In any collaborative system, there are both symmetries and asymmetries present in the design of the technology and in the ways that technology is appropriated. Yet media space research tends to focus more on supporting and fostering the symmetries than the asymmetries. Throughout more than 20 years of media space research, the pursuit of increased symmetry, whether achieved through technical

Amy Voida; Stephen Voida; Saul Greenberg; Helen Ai He

2008-01-01

360

Theory of Bergman spaces  

Microsoft Academic Search

ABSTRACT. There has been a great deal of work done in recent years on weighted Bergman spaces A 1, while others require substantial additional effort. Some of our results about integral representations, complex in- terpolation, coefficient multipliers, and Carleson measures are new even for the ordinary (unweighted) Bergman spaces of the unit disk.

H. Hedenmalm; B. Korenblum; K. Zhu

2000-01-01

361

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

362

Momentum Space Package  

NSDL National Science Digital Library

The Momentum Space package is a self-contained file for the teaching of the time evolution and visualization of energy eigenstates and their superpositions via momentum space in quantum mechanics. The file contains ready-to-run OSP programs and a set of curricular materials. The material focuses on the wave function in both position and momentum space. The Momentum Space package is an Open Source Physics curricular package written for the teaching of quantum mechanics. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the osp_p_space.jar file will run the package if Java is installed. Other quantum mechanics packages are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Quantum Mechanics.

Belloni, Mario; Christian, Wolfgang

2008-05-30

363

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

364

Space in the classroom  

NASA Astrophysics Data System (ADS)

As we enter into the space age we must realize that our space activities are likely to constitute germinal input to an extraterrestrial society and its culture which will be uniquely different from any found on Earth. It is vital that the current generation of students have the opportunity to learn as much as possible about the nature of the changes which the space age will necessitate in both terrestrial and extraterrestrial society and culture, and the impact that such changes are likely to have upon career and lifestyle. To these ends I introduced a space related course into the Niagara University curriculum with the two goals of fostering student understanding of the sociocultural forces which shape their lives and of helping to prepare them for life in the space age. This paper describes the course, its difficulties and its prospects.

Macdaniel, William E.

1986-08-01

365

Nuclear energy in space  

NASA Astrophysics Data System (ADS)

The space nuclear power studies that started in 1960s have resulted in flight demonstration tests of nuclear power systems on space vehicles of the 'Cosmos' series. The advantages of thermionic space systems (including minimum size and the possibility of increasing the power level) ensure their competitiveness at power levels up to several hundred kilowatts and with lifetime of 2 to 3 years with subsequent extensions to 5 or more years. The USSR is also developing nuclear systems to supply energy for space installations of various types, including power, propulsion, and combined systems. Further space nuclear power development requires complex scientific research which will be the most effective within the framework of international cooperation.

Ponomarev-Stepnoi, Nikolai N.

366

Space: A new frontier  

NASA Astrophysics Data System (ADS)

The challenges and the promises of space colonization present an exciting opportunity for exploring and analyzing the values, the institutions and the physical environments we have created on Earth. Here we describe an interdisciplinary course, team-taught, that examines the current state of space exploration and the innovative technologies spawned by space research. The course also explores the possible social, economic, political and international impacts of migration to space of people and industries. A course project is to design a space colony for a community of 10,000 people. Given the technical design parameters and other details, the students are to engineer socially an ideal community, bearing in mind the short lifetimes of utopian communities of the past. The process is intended to help the students gain a fair understanding of the dynamics of human societies and of the technologies we have developed that enable us to change our world and to design new worlds.

Cutolo, Mona; Miranda, Denis M.

1986-08-01

367

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

368

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

369

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.

370

25 years in space  

NASA Astrophysics Data System (ADS)

With the launch by the U.S.S.R. of the first artificial satellite, Sputnik, on October 4, 1957, the space age was inaugurated. Now, a symposium will mark the 25th anniversary of that launch with a review of the origins, motivations, and progress of the era.The National Academy of Sciences and the Smithsonian Institution's National Air & Space Museum will host ‘25 Years in Space’ on October 14. The day-long symposium, to be held at the Academy auditorium at 2100 C St., N.W., Washington, D.C., will feature three major sessions: motivations for space activity, the practical dimensions of space, and science and space. Also on the agenda is a special program on the space age and the arts. Harvey Brooks of Harvard University, Simon Ramo of TRW, Inc., and Freeman Dyson of Princeton's Institute for Advanced Study will lead these sessions. Closing remarks will be presented by Philip Morrison of the Massachusetts Institute of Technology.

371

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.

2007-04-15

372

Mycology studies in space.  

PubMed

The postflight phase of the Apollo MEED mycology attempts to identify survival according to exposure to specific quantitative space flight factors, while the second phase of studies identifies qualitative change other than cell survival [57]. Initial changes incurred in space on a fungal cell can be monitored and further examined on return of the fungal species test system to Earth. The postflight studies present a better understanding of the space environmental influences on living cells and a more clear understanding of the fungal species under examination. PMID:2325748

Volz, P A

1990-02-01

373

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

374

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.

Freudenrich, Craig

2008-01-01

375

Lyophilization process design space.  

PubMed

The application of key elements of quality by design (QbD), such as risk assessment, process analytical technology, and design space, is discussed widely as it relates to freeze-drying process design and development. However, this commentary focuses on constructing the Design and Control Space, particularly for the primary drying step of the freeze-drying process. Also, practical applications and considerations of claiming a process Design Space under the QbD paradigm have been discussed. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:3883-3887, 2013. PMID:23946165

Patel, Sajal Manubhai; Pikal, Michael J

2013-08-14

376

Fundamentals of Space Medicine  

NASA Astrophysics Data System (ADS)

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

Clément, G.

2003-10-01

377

Fundamentals of Space Medicine  

NASA Astrophysics Data System (ADS)

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

Clément, Gilles

2005-03-01

378

Safeguarding our space assets  

SciTech Connect

The vulnerability of military space systems depends on their orbits, functions, and other characteristics. The high-altitude satellites needed for warning and communications in particular could be vulnerable to prompt destruction by certain space-based systems and, in the future, possibly by ground-based high power lasers. A combination of passive countermeasures and arms control agreements could give these satellites some protection against such attack. Deployment of strategic defensive systems with the capability to reach far into space would invalidate this approach.

May, M.M.

1985-07-01

379

Semantic space configuration  

US Patent & Trademark Office Database

Representing in a database, a collection of items characterized by features. In a data processing system, determining a semantic space representations of the features across the collection. Each representation characterized by parameters and settings, and differing from each other by only one of: the value of one parameter, and the configuration of one setting. Determining, for each feature pair of a set of feature pairs, the relatedness of the first feature to the second feature in each semantic space representation. And representing the collection by the semantic space that provides the best aggregate relatedness across the set of feature pairs.

Bradford; Roger B. (Great Falls, VA)

2012-11-06

380

Achievable Space Elevators for Space Transportation and Starship Acceleration.  

National Technical Information Service (NTIS)

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

J. Pearson

1990-01-01

381

Quotients of Banach spaces and surjectively universal spaces  

Microsoft Academic Search

We characterize those classes $\\\\mathcal{C}$ of separable Banach spaces for which there exists a separable Banach space $Y$ not containing $\\\\ell_1$ and such that every space in the class $\\\\mathcal{C}$ is a quotient of $Y$.

Pandelis Dodos

2010-01-01

382

Space Rock Census  

NASA Video Gallery

NEOWISE principal investigator Amy Mainzer describes the ongoing tally of space rocks and comets amassed by NASA's Wide-field Infrared Survey Explorer, or WISE. › Asteroid and Comet Watch site › WISE mission site

Anthony Greicius

2010-05-24

383

NASA - Space Communications  

NASA Website

Glenn's space communications program is to work in partnership with the satellite communications industry and other government agencies to enable new capabilities that enhance the competitiveness of U.S. industry and support the needs of NASA ...

384

Predicting space climate change  

Microsoft Academic Search

Cosmogenic radionucleides can be used to predict the evolution of space weatherRadiation hazards are likely to increase in futureSolar energetic particle event fluences and probabilities can be predicted

L. Barnard; M. Lockwood; M. A. Hapgood; M. J. Owens; C. J. Davis; F. Steinhilber

2011-01-01

385

Space telescope, 1984  

NASA Astrophysics Data System (ADS)

The requirements and operational possibilities of the Space Telescope (ST) are presented, along with the functions of the Space Telescope Science Institute, which are: Planning the scientific program for ST; participating with the NASA project in trade off decisions; and monitoring the ST performance. Most important, the relationships of the ST to the scientific community, the relationship of the scientific community to the Space Telescope Science Institute, and how the use of the ST will be apportioned, are discussed. Assistance of the astronomers from other countries is sought in identifying key projects for the ST. The cost of the ST, with the scientific, assembly, and test problems, are also given. The interaction of the ST with the Space Transportation System is detailed.

386

Symposium on Space Gastroenterology.  

National Technical Information Service (NTIS)

Eight papers on the topic of space gastroenterology are briefly discussed. The phenomenology of changes in the digestive system; adaptive changes in hydrolysis, transport and utilization of carbohydrates in hypogravity and hypokinetic conditions; the role...

K. V. Smirnov

1987-01-01

387

Space buzz heads east  

NASA Astrophysics Data System (ADS)

While the Olympics kick off in London, a new international sporting arena is taking shape beyond Earth's orbit. Recent advances in space exploration by China and Japan remind us that curiosity about our universe is a truly universal trait.

2012-08-01

388

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.

389

Space robotics in Japan  

NASA Astrophysics Data System (ADS)

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

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

1994-03-01

390

Robots in space  

NASA Astrophysics Data System (ADS)

The first real space robots were the spacecraft belonging to the unmanned Surveyor series which conducted numerous journeys to the Moon during the 1960s. Now, as then, plans for lunar and planetary exploration see robots as an essential tool.

Evans, Ben

1993-12-01

391

Space Station Technology Summary.  

National Technical Information Service (NTIS)

The completion of the Space Station Propulsion Advanced Technology Programs established an in-depth data base for the baseline gaseous oxygen/gaseous hydrogen thruster, the waste gas resistojet, and the associated system operations. These efforts included...

R. Iacabucci S. Evans G. Briley R. A. Delventhal E. Braunscheidel

1989-01-01

392

Telerobot for Space Station.  

National Technical Information Service (NTIS)

The Flight Telerobotic Servicer (FTS), a multiple arm dexterous manipulation system, will aid in the assembly, maintenance, and servicing of the space station. Fundamental ideas and basic conceptual designs for a shuttle-based telerobot system have been p...

L. M. Jenkins

1987-01-01

393

Electrophoresis experiments for space  

NASA Astrophysics Data System (ADS)

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

Snyder, Robert S.; Rhodes, Percy H.

2000-01-01

394

Emergency medicine in space.  

PubMed

Recent events, including the development of space tourism and commercial spaceflight, have increased the need for specialists in space medicine. With increased duration of missions and distance from Earth, medical and surgical events will become inevitable. Ground-based medical support will no longer be adequate when return to Earth is not an option. Pending the inclusion of sub-specialists, clinical skills and medical expertise will be required that go beyond those of current physician-astronauts, yet are well within the scope of Emergency Medicine. Emergency physicians have the necessary broad knowledge base as well as proficiency in basic surgical skills and management of the critically ill and injured. Space medicine shares many attributes with extreme conditions and environments that many emergency physicians already specialize in. This article is an introduction to space medicine, and a review of current issues in the emergent management of medical and surgical disease during spaceflight. PMID:17239732

Stewart, Lowan H; Trunkey, Donald; Rebagliati, G Steve

2007-01-01

395

Radiation effects in space  

SciTech Connect

The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

Fry, R.J.M.

1986-01-01

396

European space programme  

NASA Astrophysics Data System (ADS)

Successful European Space Agency (ESA) programs include the Ariane launcher development, the Meteosat meteorological satellites and the Intelsat 6, ECS (European Communications Satellite) series of communications satellites. The ESA's policy of placing contracts with industrial companies in its 13 member countries has contributed to the strategic development of European high technology in the world market. The ESA's long-term programs, in addition to the Ariane launcher and Columbus/Hermes space-station/spaceplane programs, include participation in the International Space Station program, the Data Relay Satellite system and a variety of space applications programs. Two high-performance satellites to be placed in polar orbits will contribute to European environmental and climate variation studies and, together with the Polar Platform sector of the Columbus program, will drive the establishment and development of new institutions, industrial structures and infrastructure.

Luton, J.-M.

1992-02-01

397

Robots in space  

Microsoft Academic Search

The first real space robots were the spacecraft belonging to the unmanned Surveyor series which conducted numerous journeys to the Moon during the 1960s. Now, as then, plans for lunar and planetary exploration see robots as an essential tool.

Ben Evans

1993-01-01

398

Nutrition for Space Exploration.  

National Technical Information Service (NTIS)

Nutrition has proven to be critical throughout the history of human exploration, on both land and water. The importance of nutrition during long-duration space exploration is no different. Maintaining optimal nutritional status is critical for all bodily ...

S. M. Smith

2005-01-01

399

Life in Space.  

National Technical Information Service (NTIS)

The document is comprised of an interview with Oleg G. Gazenko, Director of the Institute of Medical and Biological Problems of the USSR Ministry of Health, concerning various aspects of space medicine.

O. G. Gazenko

1971-01-01

400

Space-Based Seti.  

National Technical Information Service (NTIS)

Space-based antenna systems for the search of signals from extra-terrestrial intelligence are discussed. Independent studies of the ecliptic solar-sailing transfer problem from the geosynchronous departure orbit to Sun-Earth collinear transterrestrial lib...

W. Stuiver

1990-01-01

401

Fireworks in Space.  

National Technical Information Service (NTIS)

Inspired by fireworks, our ancestors invested rockets. The ignition of rockets (including the carrier rocket which is responsible for carrying a satellite into space) is conducted by a special starting device. The operating principle is to light with elec...

1986-01-01

402

Intergalactic magnetic fields and structure formation  

Microsoft Academic Search

The observational evidence for magnetic fields in clusters of galaxies will be briefly reviewed. It is possible such fields are stongly affected by gas dynamical processes driven by, e.g., cluster mergers. Numerical MHD investigations of such processes, as well as studies of the role of MHD processes affecting large scale structure formation, will be reviewed.

J. M. Stone

2000-01-01

403

Dissipation and enrichment in the intergalactic medium  

NASA Astrophysics Data System (ADS)

Gravity is easy. The most intractable problems in our understanding of the formation and evolution of galaxies and galaxy systems derive from the complex things which baryons can do, but dark matter cannot. Hot gas cools, moving gas shocks, nucleosynthesis generates both energy and heavy elements which can escape from galaxies into the surrounding IGM. These processes are coupled together via subtle positive and negative feedback loops, and span a huge dynamic range which defeats attempts at numerical simulation. In this talk I will review the ways in which the structure, scaling properties and element abundances of the IGM in galaxy clusters, which can now be traced by XMM-Newton and Chandra more effectively than ever before, are providing information which may help us to unpick some of this interlocked puzzle.

Ponman, T. J.

404

Mutant Fungus from Space  

NSDL National Science Digital Library

Space expert Yuri Karash of Russia says that he anticipates that the Mir Space Station could bring virulent new strains of fungus to earth when it splashes down later this month. Various types of fungus, whose smell is the first thing visitors to Mir notice, grow behind panels and in air-conditioning units on the spacecraft and have likely mutated. This article from the BBC News online covers the story.

2001-01-01

405

Exploring Earth from Space  

NSDL National Science Digital Library

This set of lithographs from the ISS EarthKAM program contains an educators' guide, student information and worksheets, and several Earth photos taken from the Space Shuttle. Shuttle astronauts and the ISS EarthKAM program provide photos of our planet from the unique perspective of Earth orbit. This resource can enhance students' studies of Earth and space science, geography, social studies, mathematics, and educational technologies.

2002-12-01

406

Configuration Space Theory of  

Microsoft Academic Search

The configuration space theory of (non-relativistic) three-body scattering is reviewed, with two main objectives in mind: (i) to derive from a very different approach, wherein comparatively little use is made of questionable mathematical manipulations (e.g. operator techniques or the representation of functions by infinite integrals) the general expressions for reaction rates customarily deduced via momentum space procedures; (ii) to determine

E. Gerjuoy

1971-01-01

407

Space extreme design  

Microsoft Academic Search

This paper is an introduction to the following five articles, that have been conceived together as one chapter on habitability\\u000a consideration for outer space habitations. Those contributions are made from authors in different fields, cultures and countries\\u000a working with the Extreme-Design.eu research group. Projects, theories and requirements are referred to the context of outer\\u000a space habitats, where for the love

Irene Lia Schlacht

2011-01-01

408

Normal Biconformal Spaces  

Microsoft Academic Search

A new 8-dimensional conformal gauging avoids the unphysical size change,\\u000athird order gravitational field equations, and auxiliary fields that prevent\\u000ataking the conformal group as a fundamental symmetry. We give the structure\\u000aequations, gauge transformations and intrinsic metric structure for the new\\u000abiconformal spaces. We prove that a torsion-free biconformal space with exact\\u000aWeyl form, closed dilational curvature and trace-free

James T. Wheeler

1997-01-01

409

Man in space.  

PubMed

The Challenger disaster focused attention on the hazards as well as the possibilities of man in space. The physiological effects of prolonged weightlessness include important changes in vestibular, bone, muscle, cardiovascular, blood, renal, and pulmonary function. Much has been learned from US and Soviet experiments, but large areas of ignorance remain. Exceptional opportunities for physiological research are provided by Spacelab, a pressurized laboratory planned as a payload of the Space Shuttle. PMID:11539062

West, J B

1986-12-01

410

Next Generation Space Telescope  

NASA Astrophysics Data System (ADS)

The Next Generation Space Telescope (NGST) will be an 8 m class deployable, radiatively cooled telescope, optimized for the 1-5 ?m band, with zodiacal background limited sensitivity from 0.6 to 10 ?m or longer, operating for 10 yr near the Earth-Sun second LAGRANGIAN POINT (L2). It will be a general-purpose observatory, operated by the SPACE TELESCOPE SCIENCE INSTITUTE (STScI) for competitively s...

Smith, E.; Murdin, P.

2002-01-01

411

Energy level spacing distributions  

Microsoft Academic Search

The probability function P¹(s) for the next-nearest neighbor ; spacing in the infinite dimensional limit, is computed and compared with Porter's ; result for 3 x 3 random real symmetric matrices. The probability function for ; DysOn's unitary ensemble BETA = 2; P\\/sup o\\/(s; 2), for the nearest neighbor ; spacing, is also computed. It is compared with results for

P. Kahn

1963-01-01

412

European space transport systems  

NASA Astrophysics Data System (ADS)

Present and future European space transport systems are discussed. The development of the ARIANE 1-4 family is briefly reviewed, and the space transport competition between Europe and the United States is described. The HM60 and European propulsion technology are discussed, giving the characteristics of various engines. The features of the future European cargo rocket ARIANE 5P are outlined, and the need for orbital maneuvering vehicles in low earth orbit is discussed.

Lo, R. E.

413

Introduction to Space Flight  

NSDL National Science Digital Library

These online lecture notes introduce students to the basics of space flight. Topics covered include: rocket motors, history of rockets, the scientific method, astronomy basics, the solar system, the universe, space flight missions, spacecraft, remote sensing, astronauts, and future spaceflight missions. This website also provides useful links and exercises intended for students taking this course. These exercises can provide teachers with ideas for their own classes.

Erickson, Lance

2005-06-07

414

Environmental and space electromagnetics  

Microsoft Academic Search

The present volume on environmental and space electromagnetics discusses spacecraft EM environment, natural and triggered lightning, atmospherics, whistlers, and emissions, and natural VLF\\/ELF radio noise. Attention is given to terrestrial and extraterrestrial noise environment, planetary lightning and cosmic plasma noise, noise and communication statistics, and space communication and measurement. Topics addressed include high-power electromagnetics, seismoelectric emissions, ball lightning, and meteorologico-electric

Hiroshi Kikuchi

1991-01-01

415

Audio problems in space  

Microsoft Academic Search

Communication channel capacity is almost invariably at a premium between space vehicles and the earth. In the Apollo moon exploration program, plans call for the use of a special audio processing technique to enhance the signal-to-noise ratio. Extremely deep space probes such as the Mars Mariner IV now use very low bit rate transmissions because of signal-to-noise considerations: future manned

W. Kock

1965-01-01

416

Targeting across displayless space  

Microsoft Academic Search

Multi-monitor displays and multi-display environments are now common. Cross-display cursor movement, in which a user moves the pointer from one display to another, occurs frequently in these settings. There are several techniques for supporting this kind of movement, and these differ in the way that they deal with displayless space (the physical space between displays). Stitching is the method used

Miguel A. Nacenta; Regan L. Mandryk; Carl Gutwin

2008-01-01

417

Space-quest, experiments with quantum entanglement in space  

Microsoft Academic Search

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

R. Ursin; T. Jennewein; J. Kofler; J. M. Perdigues; L. Cacciapuoti; C. J. de Matos; M. Aspelmeyer; A. Valencia; T. Scheidl; A. Acin; C. Barbieri; G. Bianco; C. Brukner; J. Capmany; S. Cova; D. Giggenbach; W. Leeb; R. H. Hadfield; R. Laflamme; N. Lütkenhaus; G. Milburn; M. Peev; T. Ralph; J. Rarity; R. Renner; E. Samain; N. Solomos; W. Tittel; J. P. Torres; M. Toyoshima; A. Ortigosa-Blanch; V. Pruneri; P. Villoresi; I. Walmsley; G. Weihs; H. Weinfurter; M. Zukowski; A. Zeilinger

2009-01-01

418

Space-based magnetometers  

NASA Astrophysics Data System (ADS)

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. Several types of instruments used to measure magnetic fields aboard spacecraft and their capabilities and limitations are described according to whether they measure scalar or vector fields. The very large dynamic range associated with magnetic fields of natural origin generally dictates the use of optimized designs for each particular space mission although some wide-range, multimission magnetometers have been developed and used. Earth-field magnetic mapping missions are the most demanding in terms of absolute accuracy and resolution, approaching <1 part in 100 000 in magnitude and a few arcsec in direction. The difficulties of performing sensitive measurements aboard spacecraft, which may not be magnetically clean, represent a fundamental problem which must be addressed immediately at the planning stages of any space mission that includes these measurements. The use of long, deployable booms to separate the sensors from the sources of magnetic contamination, and their impact on system design are discussed. The dual magnetometer technique, which allows the separation of fields of external and spacecraft origin, represents an important space magnetometry tool which can result in significant savings in complex contemporary spacecraft built with minimum magnetic constraints. Techniques for in-flight estimation of magnetometer biases and sensor alignment are discussed briefly, and highlight some basic considerations within the scope and complexity of magnetic field data processing and reduction. The emerging field of space weather is also discussed, including the essential role that space-based magnetic field measurements play in this complex science, which is just in its infancy. Finally, some considerations for the future of space-based magnetometers are presented. Miniature, mass produced sensors based on magnetoresistance effects and micromachined structures have made significant advances in sensitivity but have yet to reach the performance level required for accurate space measurements. The miniaturization of spacecraft and instruments to reduce launch costs usually results in significantly increased magnetic contamination problems and degraded instrument performance parameters, a challenge that has yet to be solved satisfactorily for ``world-class'' science missions. The rapidly disappearing manufacturing capabilities for high-grade, low noise, soft magnetic materials of the Permalloy family is a cause of concern for the development of high performance fluxgate magnetometers for future space missions.

Acuña, Mario H.

2002-11-01

419

Space charge in proton linacs  

NASA Astrophysics Data System (ADS)

Space charge effects on beam dynamics in linear accelerators are discussed. Practical linac beam dynamics calculation methods which include space charge effects are discussed. Also, the status of beam performance experiments including space charge studies are summarized.

Wangler, T. P.; Merrill, F.; Rybarcyk, L.; Ryne, R.

1998-11-01

420

Space Debris Mitigation CONOPS Development.  

National Technical Information Service (NTIS)

Space debris remains an unsolved hazard for space operators and astronomers alike. Passive debris mitigation techniques have been enumerated and codified by the UNCOPUOS and IADC and several proposals for actively mitigating space debris have been present...

E. B. Alejandro

2013-01-01

421

Mammalian development in space.  

PubMed

Life on Earth, and thus the reproductive and ontogenetic processes of all extant species and their ancestors, evolved under the constant influence of the Earth's l g gravitational field. These considerations raise important questions about the ability of mammals to reproduce and develop in space. In this chapter, I review the current state of our knowledge of spaceflight effects on developing mammals. Recent studies are revealing the first insights into how the space environment affects critical phases of mammalian reproduction and development, viz., those events surrounding fertilization, embryogenesis, pregnancy, birth, postnatal maturation and parental care. This review emphasizes fetal and early postnatal life, the developmental epochs for which the greatest amounts of mammalian spaceflight data have been amassed. The maternal-offspring system, the coordinated aggregate of mother and young comprising mammalian development, is of primary importance during these early, formative developmental phases. The existing research supports the view that biologically meaningful interactions between mothers and offspring are changed in the weightlessness of space. These changes may, in turn, cloud interpretations of spaceflight effects on developing offspring. Whereas studies of mid-pregnant rats in space have been extraordinarily successful, studies of young rat litters launched at 9 days of postnatal age or earlier, have been encumbered with problems related to the design of in-flight caging and compromised maternal-offspring interactions. Possibilities for mammalian birth in space, an event that has not yet transpired, are considered. In the aggregate, the results indicate a strong need for new studies of mammalian reproduction and development in space. Habitat development and systematic ground-based testing are important prerequisites to future research with young postnatal rodents in space. Together, the findings support the view that the environment within which young mammals develop, comprised of its mother and siblings, is of paramount importance in interpreting spaceflight effects. PMID:14631635

Ronca, April E

2003-01-01

422

Space Science Network Northwest  

NASA Astrophysics Data System (ADS)

Space Science Network Northwest (S2N2) is a new NASA Office of Space Science Education Broker/Facilitator that serves the states of Alaska, Hawaii, Idaho, Montana, Oregon, Washington and Wyoming. The headquarters of S2N2 is at the University of Washington in Seattle and the Director is Julie Lutz (206-543-0214; nasaerc@u.washington.edu). Each state has an S2N2 representative. Their contact information can be found on the Web site (www.s2n2.org) or by contacting Julie Lutz. The purpose of S2N2 is to form and nurture partnerships between space scientists and others (K-12 teachers, schools and districts, museums, planetariums, libraries, organizations such as Girl Scouts, amateur astronomy clubs, etc.). S2N2 can help space scientists come up with appropriate activities and partners for education and public outreach proposals and projects. S2N2 also provides information and advice about education materials and programs that are available from all of the Office of Space Science missions and scientific forums (Solar System Exploration, Structure and Evolution of the Universe, Sun-Earth Connection, Astronomical Search for Origins).

Lutz, J.

2002-12-01

423

Space Resources Utilization Roundtable  

NASA Astrophysics Data System (ADS)

This volume contains abstracts on various topics. These topics include; Economics of Lunar Mineral Exploration; Lunar Solar Power System and Lunar Development; Space Resource Roundtable Rationale; Successfully Mining Asteroids and Comets; Lunar Polar Ice: Method for Mining the New Resource for Exploration; Acoustic Shaping: Enabling Technology for a Space-based Economy; Return to the Moon: A New Strategic Evaluation; Spacewatch Discovery and Study of Accessible Asteroids; Role of Mining in Space Development; A Commercial/Lunar Resources Exploration Concept; Radar Reconnaissance of Near-Earth Asteroids; Solar Energy Conversion Using In Situ Lunar Soil; The Application of Thermal Plasmas to Ore Reduction for In Situ Resource Utilization; Prospecting Near-Earth Asteroids from the Ground; Some Implications of Space Tourism for Extraterrestrial Resources; An Overview of NASA's Current In Situ Consumable Production (ISCP) Development Activities and Goals; Prospectives on Lunar Helium-3; Self-Propagating High-Temperature Synthesis for In Situ Materials Processing; Subsurface Exploration from Lander and Rover Platforms with Seismic Surface Waves; Space Weathering and the Formation of Lunar Soil: The Moon as the Model for all Airless Bodies in the Solar System; and Acoustic Shaping in Microgravity: Technology Issues.

1999-01-01

424

Space debris executive summary  

SciTech Connect

Spacecraft, boosters, and fragments are potential hazards to space vehicles, and it is argued that collisions between them could produce a cascade that could preclude activity in LEO in 25 to 50 years. That has generated pressure for constraints on military space operations, so the AF SAB performed a study of technical aspects of the debris problem. The Study was independent of the efforts of the Air Force Space Command (AFSPC) as well as those of and NASA Johnson Space Center (JSC), which is the principal advocate for cascades and constraints. Most work on space debris has been performed by AFSPC and JSC, so the Study was in part an assessment of their efforts, in which both have been cooperative. The Study identified the main disagreements and quantified their impacts. It resolved some issues and provided bounds for the rest. It treated radar and optical observations; launch, explosion, and decay rates; and the number and distribution of fragments from explosions and collisions. That made it possible to address hazard to manned spacecraft at low altitudes and the possibility of cascading at higher altitudes, both of which now appear less likely.

Canavan, G.H.; Judd, O.; Naka, R.F.

1996-09-01

425

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

Code of Federal Regulations, 2011 CFR

...cofferdam, and spaces containing cargo piping. 154.1210 Section 154.1210 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and...

2011-10-01

426

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

SciTech Connect

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

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

2009-08-01

427

Integration of space syntax into GIS for modelling urban spaces  

Microsoft Academic Search

In the past, many methods of spatial analysis have been developed for a better understanding and modelling of real-world phenomena. However there is still a need for exploration of new analytical techniques for modelling urban spaces. Space syntax models the spatial configurations of urban spaces by using a connectivity graph representation. Such a configuration of space identifies patterns that can

Bin Jiang; Christophe Claramunt; Björn Klarqvist

2000-01-01

428

Input space versus feature space in kernel-based methods  

Microsoft Academic Search

This paper collects some ideas targeted at advancing our understanding of the feature spaces associated with support vector (SV) kernel functions. We first discuss the geometry of feature space. In particular, we review what is known about the shape of the image of input space under the feature space map, and how this influences the capacity of SV methods. Following

Bernhard Schölkopf; Sebastian Mika; Christopher J. C. Burges; Phil Knirsch; Klaus-robert Müller; Gunnar Rätsch; Alexander J. Smola

1999-01-01

429

On lipschitz embedding of finite metric spaces in Hilbert space  

Microsoft Academic Search

It is shown that anyn point metric space is up to logn lipeomorphic to a subset of Hilbert space. We also exhibit an example of ann point metric space which cannot be embedded in Hilbert space with distortion less than (logn)\\/(log logn), showing that the positive result is essentially best possible. The methods used are of probabilistic nature. For instance,

J. Bourgain

1985-01-01

430

Space Ethics and Protection of the Space Environment  

Microsoft Academic Search

The construction of the International Space Station in low Earth orbit and the formulation of plans to search for life on Mars - one day by means of manned missions - indicate that mankind is intent on making the space environment part of its domain. Publicity surrounding space tourism, in-space `burials' and the sale of lunar `real estate' suggests that,

Mark Williamson

2002-01-01

431

Integration Of Space Weather Into Space Situational Awareness  

Microsoft Academic Search

Rapid assessment of space weather effects on satellites is a critical step in anomaly resolution and satellite threat assessment. That step, however, is often hindered by a number of factors including timely collection and delivery of space weather data and the inherent complexity of space weather information. As part of a larger, integrated space situational awareness program, Los Alamos National

G. Reeves; Geoffrey D

2010-01-01

432

ISS Update: SpaceX Space Act Agreement Status  

NASA Video Gallery

NASA Public Affairs Officer Kyle Herring interviews Jon Cowart, Commercial Crew Program, Partner Manager for Space Exploration Technologies (SpaceX), about the status of Space Act Agreement. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #askStation. For the latest news about the space station, visit http://www.nasa.gov/station.

Mark Garcia

2012-03-20

433

High voltages in space: innovation in space insulation  

Microsoft Academic Search

The results of the Space Power Experiment Aboard Rockets (SPEAR) rocket series, which evaluated the effects of the space environment on high voltage (HV) insulation, are described. SPEAR I demonstrated that voltages >40 kV could be sustained in the space environment. SPEAR II ground-based simulations and tests demonstrated a number of new technologies for utilizing the properties of the space

P. Rustan; H. Garrett; M. J. Schor

1993-01-01

434

Space telescope design considerations  

NASA Astrophysics Data System (ADS)

The design considerations for astronomical space telescopes cover many disciplines but can be simplified into two overarching constraints: the desire to maximize science while adhering to budgetary constraints. More than ever, understanding the cost implications up front will be critical to success. Science performance can be translated into a set of simple performance metrics that set the requirements for design options. Cost is typically estimated by considering mass, complexity, technology maturity, and heritage. With this in mind, we survey the many diverse design considerations for a space telescope and, where appropriate, relate them to these basic performance metrics. In so doing, we hope to provide a roadmap for future space telescope designers on how best to optimize the design to maximize science and minimize total cost.

Feinberg, Lee; Cohen, Lester; Dean, Bruce; Hayden, William; Howard, Joseph; Keski-Kuha, Ritva

2012-01-01

435

Space research and SPARTAN  

NASA Astrophysics Data System (ADS)

For a number of years, space research has been primarily conducted with sounding rockets and orbiting satellites. The use of satellites has disadvantages related to cost and the long lead time from design to launch, while a drawback in the case of sounding rockets is the short flight time of only a few minutes. The development of the Shuttle led to the proposal to employ for space research an autonomous free-flying payload deployed and recovered by the Shuttle. The proposed payload, called SPEAR (Small Payload Ejection and Recovery), looked very much like a rocket payload. Subsequently, the payload developed into a more compact form, and its name became Spartan-1. Attention is given to the demands of space research, the Spartan-1 payload, the payload functional control system, the thermal control system, the Spartan-1 mission, and the future of Spartan.

Cruddace, R. G.; Fritz, G. G.; Shrewsberry, D. J.

1985-01-01

436

Project for Public Spaces  

NSDL National Science Digital Library

Given the heated discussion and debate surrounding the future redevelopment of the World Trade Center site, it is no surprise that there is a great deal of interest in public places, along with much dissent about what makes an effective and meaningful public place. Drawing on the work of the late William H. Whyte (whose seminal book, The Social Life of Small Urban Spaces is still read today), the Project for Public Spaces is dedicated to creating and sustaining public spaces that build communities. The site contains a number of best practices information on such places as parks, plazas, streets, public buildings, and public markets that will be of great interest to planners, civic officials, landscape architects, and anyone seeking to restore meaning and usability to a wide variety of places. Additionally, visitors can elect to subscribe to PPS's free bi-monthly newsletter, Making Places.

437

The Space Solar Telescope  

NASA Astrophysics Data System (ADS)

(On behalf of the SST group) The Space Solar Telescope (SST) is a Chinese space project, which was first proposed in the mid of 1990s. The main purpose is to observe the basic structures and understand the instrinsic properties of solar magnetic field with a 1m optical telescope equiped with a two-dimensional real-time spectrograph and high-accuracy polarimeter. In addition, through coordinated, wide spectral coverage, highly resolving and continuous observations, it can study the evolution of multi-scale transients and various phenomena in the solar atmosphere, investigate the heating mechanism of the chromosphere and the corona, and study the mechanism of the energy build-up and release in solar flares and CMEs. Recently, along with the progress of STEREO, Hinode, SDO and other space projects, the scientific objectives and payloads of SST have been updated. In this presentation, we will briefly introduced the updated payloads and relevant progress.

Deng, Y.

2012-12-01

438

Space radiation protection issues.  

PubMed

The complex charged particle environments in space pose considerable challenges with regard to potential health consequences that can impact mission design and crew selection. The lack of knowledge of the biological effects of different ions in isolation and in combination is a particular concern because the risk uncertainties are very high for both cancer and non-cancer late effects. Reducing the uncertainties is of high priority. Two principal components of space radiation each raise different concerns. Solar particle events (SPE) occur sporadically and are comprised primarily of low- to moderate-energy protons. Galactic cosmic radiation (GCR) is isotropic and relatively invariant in dose rate. GCR is also dominated by protons, but the energy range is wider than in SPE. In addition, the contribution of other light and heavy ions to the health risks from GCR must be addressed. This paper will introduce the principal issues under consideration for space radiation protection. PMID:23032885

Kronenberg, Amy; Cucinotta, Francis A

2012-11-01

439

Radioelectronics and space exploration  

NASA Astrophysics Data System (ADS)

Citing the 23 years since Yuriy Gagarin's first radio transmission from outer space, the developments in radio communications and their role in mission control are summarized. Use of satellites for radio and television links with ground stations are an important part of information exchange. Construction and preventive maintenance activities by Soviet cosmonauts, use of radio technology for docking procedures and the reliability of such equipment, and the growing role of computer technology in space vehicles with human crews and pilotless craft are discussed. Automatic interplanetary vehicles that have landed on the moon, Mars and Venus, as well as artificial earth satellites, are facilitating weather and communication advances. Mock space equipment using radio and computer technology is of great importance for training cosmonauts. Despite all these practical applications, optimum utilization of automated equipment has yet to be achieved, and offers further challenge to Soviet and other engineers and technicians.

Sarafanov, T.; Bogoroditskiy, Y.; Milyukov, I.

1985-03-01

440

Education in space science  

NASA Astrophysics Data System (ADS)

The educational process for teaching space science has been examined as a topic at the 17th European Space Agency Symposium on European Rocket and Balloon, and Related Research. The approach used for an introductory course during the past 18 years at Penn State University is considered as an example. The opportunities for using space science topics to motivate the thinking and efforts of advanced undergraduate and beginning graduate students are examined. The topics covered in the introductory course are briefly described in an outline indicating the breath of the material covered. Several additional topics and assignments are included to help prepare the students for their careers. These topics include discussions on workplace ethics, project management, tools for research, presentation skills, and opportunities to participate in student projects.

Philbrick, C. Russell

2005-08-01

441

Sounds of Space  

NASA Astrophysics Data System (ADS)

Starting in the early 1960s, spacecraft-borne plasma wave instruments revealed that space is filled with an astonishing variety of radio and plasma wave sounds, which have come to be called "sounds of space." For over forty years these sounds have been collected and played to a wide variety of audiences, often as the result of press conferences or press releases involving various NASA projects for which the University of Iowa has provided plasma wave instruments. This activity has led to many interviews on local and national radio programs, and occasionally on programs haviang world-wide coverage, such as the BBC. As a result of this media coverage, we have been approached many times by composers requesting copies of our space sounds for use in their various projects, many of which involve electronic synthesis of music. One of these collaborations led to "Sun Rings," which is a musical event produced by the Kronos Quartet that has played to large audiences all over the world. With the availability of modern computer graphic techniques we have recently been attempting to integrate some of these sound of space into an educational audio/video web site that illustrates the scientific principles involved in the origin of space plasma waves. Typically I try to emphasize that a substantial gas pressure exists everywhere in space in the form of an ionized gas called a plasma, and that this plasma can lead to a wide variety of wave phenomenon. Examples of some of this audio/video material will be presented.

Gurnett, D. A.

2005-12-01

442

Basics of Space Flight  

NSDL National Science Digital Library

This tutorial is designed to help identify the range of concepts associated with deep space missions and illustrate the relationships among them. The three sections deal with the environment of space (e.g., the solar system, spatial coordinates and timing conventions, interplanetary trajectories); flight projects (how missions are concieved and designed, experimentation, spacecraft subsystems, etc.); and operations (launch phase, cruise phase, data-gathering, and similar subjects). Each chapter concludes with a quiz that lets users test their knowledge. There is also a user's guide, glossary, guide to units of measure, and links to additional information. A downloadable, printable version is provided.

443

Terror in Space  

NSDL National Science Digital Library

This website is part of NOVA Online, which is produced for the Public Broadcasting System (PBS) by the Science Unit at WGBH in Boston. This site accompanies the television program and discusses the Russian space station, Mir. There is a tour of Mir with parts, functions, and videos of the interior, a description of a typical day on Mir, as well as mishaps that have occurred on board Mir and elsewhere. The International Space Station (ISS) is also discussed. A teacher's guide offers viewing ideas and class activities, as well as links to additional resources. The accompanying video is available through mail order.

444

China today: Space industry  

NASA Astrophysics Data System (ADS)

A complete and systematic review of the development, major achievements, and basic experiences of space industry in China is presented. Particular attention is given to research and development organizations, space activities, and technological developments; six types of launch vehicles for the artificial satellite, including the Long March-1, -2, -3, -4, and 2E, and Storm 1; artificial satellites including scientific satellite, recoverable remote sensing satellite, geostationary communications satellite, and meteorological satellite. Materials and processing techniques, and large ground test facilities are also discussed.

Liu, Jiyuan

445

The organized Space Station  

NASA Astrophysics Data System (ADS)

Space Station organization designers should consider the onboard stowage system to be an integral part of the environment structured for productive working conditions. In order to achieve this, it is essential to use an efficient inventory control system able to track approximately 50,000 items over a 90-day period, while maintaining peak crew performance. It is noted that a state-of-the-art bar-code inventory management system cannot satisfy all Space Station requirements, such as the location of a critical missing item.

Lew, Leong W.

446

The Space Place  

NSDL National Science Digital Library

The Space Place demonstrates and explains scientific concepts related to astronomy in a fun, hands-on manner that is tailored to grade school children. Sponsored by NASA, the California Institute of Technology, and a consortium of other technology partners, The Space Place offers a simple, clutter-free forum where children can learn about such topics as stars, the earth, ions, and interferometry by baking cookies, navigating a maze, and solving a riddle. The explanations that follow the activities are clear and concise enough for even adults to understand.

447

Muscle Loss in Space  

NSDL National Science Digital Library

In this activity students measure the change in the area of calf muscle from transverse MRI images collected from an astronaut before and after a prolonged journey in space. They measure and compare the total area of calf muscle from before and after flight to determine if muscle loss has occurred. The lesson introduces some reasons for the muscle loss, measures to reduce the loss, and other effects of space flight. Students perform the image analysis with WebImage, a customized version of ImageJ running in a browser.

448

Adventure into space.  

PubMed

The exploration of the universe has captured mankind's interest since the earliest attempts to understand the sun, moon, planets, comets, and stars. The last few decades have seen explosive advances of knowledge, sparked by technological advances and by our entry into the space age. Achievements in solar system exploration, discoveries both in the Milky Way and in the farther universe, and challenges for the future are discussed. Of major concern worldwide is the need for people of goodwill in all nations to concentrate on the peaceful uses of outer space and on international collaboration. PMID:17755462

Burbidge, E M

1983-07-29

449

Adventure into Space  

NASA Astrophysics Data System (ADS)

The exploration of the universe has captured mankind's interest since the earliest attempts to understand the sun, moon, planets, comets, and stars. The last few decades have seen explosive advances of knowledge, sparked by technological advances and by our entry into the space age. Achievements in solar system exploration, discoveries both in the Milky Way and in the farther universe, and challenges for the future are discussed. Of major concern worldwide is the need for people of goodwill in all nations to concentrate on the peaceful uses of outer space and on international collaboration.

Burbidge, E. Margaret

1983-07-01

450

Spitzer Space Telescope  

NSDL National Science Digital Library

This website, maintained by the California Institute of Technology, describes the two-and-a half-year mission of the Spitzer Space Telescope to "obtain images and spectra by detecting infrared energy, or hear, radiated by objects in space between wavelengths of three and 180 microns." Scientists can find images and explanations of the instrumentation, data and analysis, and an overview of the project at the Astronomers' Site. At the Cool Cosmos link, educators and students can find fun classroom activities, a cosmic reference guide, and astronomy tutorials. Everyone can discover the latest news and images collected by Spitzer. The materials for the general public are also offered in Spanish.

451

European Space Agency: Rosetta  

NSDL National Science Digital Library

Rosetta is the European Space Agency's comet exploration spacecraft. Materials presented here describe the space craft and its mission, which is to rendezvous with and orbit Comet 67 P/Churyumov-Gerasimenko, and soft-land an instrument package on the comet's nucleus. En route to the comet, it will perform fly-bys of two asteroids, Steins and Lutetia. Topics include a mission summary, background science, information on the orbiter and lander, and a mission schedule. An image gallery is also provided that contains pictures of the spacecraft, imagery taken by the spacecraft, pictures of the launch, and others.

452

Space Shuttle ascent aborts  

NASA Astrophysics Data System (ADS)

Specific guidance functions and trajectory design of return to launch site (RTLS) and transoceanic abort landing (TAL) intact abort profiles, as well as the increasing emphasis on contingency aborts, are presented. Various systems failures including Space Shuttle main engine failures and detailed technical analyses, including the design of powered flight abort trajectories, are considered. The most critical of flight abort situations is the RTLS, while TAL is the preferred abort when uphill capability is no longer available. It is concluded that one principle must remain to ensure continuing success of Space Shuttle flights: namely that intact and contingency aborts necessitate development to ensure safe return of the vehicle, payload, and crew whenever possible.

Schmidgall, Richard A.

1989-09-01

453

On classes of Banach spaces admitting ‘‘small” universal spaces  

Microsoft Academic Search

We characterize those classes $\\\\ccc$ of separable Banach spaces admitting a\\u000aseparable universal space $Y$ (that is, a space $Y$ containing, up to\\u000aisomorphism, all members of $\\\\ccc$) which is not universal for all separable\\u000aBanach spaces. The characterization is a byproduct of the fact, proved in the\\u000apaper, that the class $\\\\mathrm{NU}$ of non-universal separable Banach spaces is\\u000astrongly

Pandelis Dodos

2009-01-01

454

Space Storms, Ring Current and Space-Atmosphere Coupling  

Microsoft Academic Search

\\u000a Space storms are the prime complex processes of space weather. They interconnect, in a uniquely global manner, the Sun, the\\u000a interplanetary space, the terrestrial magnetosphere and atmosphere, and occasionally the surface of the Earth. Energy from\\u000a the Sun drives a continuous interaction of these distinct but coupled regions. The essential element of space storms in the\\u000a near-Earth space environment is

Ioannis A. Daglis

455

Higher Education Space: Future Directions  

ERIC Educational Resources Information Center

|This paper reports on a study of changing demands for space in United Kingdom (UK) higher education. Physical spaces that universities require are related to their functions in complex ways, and the connections between space and academic performance are not well understood. No simple algorithm can calculate a single university's space needs, but…

Temple, Paul; Barnett, Ronald

2007-01-01

456

Science on a space elevator  

Microsoft Academic Search

The Space Elevator (SE) represents a major paradigm shift in space access. If the SE's promise of low cost access can be realized, everything becomes economically more feasible to accomplish in space. In this paper we describe in-situ science stations mounted on a science-dedicated space elevator tether. The concept presented here involves a carbon nanotube ribbon that is constructed by

B. E. Laubscher; A. M. Jorgensen

2004-01-01

457

Space bioreactors and their applications  

Microsoft Academic Search

Space biology is a young and rapidly developing discipline comprising basic research and biotechnology. With the prospect of longer space missions and the construction of the International Space Station several aspects of biotechnology will play a prominent role in space. In fact, biotechnological processes allowing the recycling of vital elements, such as oxygen or water, and the in-flight production of

Isabelle Walther

2002-01-01

458

Space Shuttle: The Renewed Promise.  

ERIC Educational Resources Information Center

This booklet describes the history of the space shuttle, especially after the Challenger accident. Topics include: (1) "Introduction"; (2) "Return to Flight: The Recovery"; (3) "Space Shuttle Chronology"; (4) "Examples of Other Modifications on Shuttle's Major Systems"; (5) "Space Shuttle Recovery Chronology"; (6) "Poised for Launch: Space Shuttle…

McAleer, Neil

459

USSR space life sciences digest  

SciTech Connect

Research in exobiology, life sciences technology, space biology, and space medicine and physiology, primarily using data gathered on the Salyut 6 orbital space station, is reported. Methods for predicting, diagnosing, and preventing the effects of weightlessness are discussed. Psychological factors are discussed. The effects of space flight on plants and animals are reported. Bioinstrumentation advances are noted.

Lewis, C.S.; Donnelly, K.L.

1980-01-01

460

FUNDAMENTAL GROUPS AND COVERING SPACES  

Microsoft Academic Search

In this paper, I will briefly develop the theory of fundamental groups and covering spaces of topological spaces. Then I will point toward the manner in which covering spaces can be used prove some cool things in group theory. I presume a cursory knowledge of topological spaces—open and closed sets, continuous functions, and homeomorphisms should be enough background knowledge.

ETHAN JERZAK

461

SpaceSafari  

ERIC Educational Resources Information Center

|Exploring the Solar System in the elementary school curriculum has traditionally involved activities, such as building scale models, to help students visualize the vastness of space and the relative size of the planets and their orbits. Today, numerous websites provide a wealth of information about the sun and the planets, combining text, photos,…

Scarlatos, Tony

2013-01-01

462

Spaces between the Lines  

ERIC Educational Resources Information Center

|A variety of subject matter, including foliage, tree roots, branches, and flowering plants, provides opportunities to study spaces and shapes and offers connections to interdisciplinary study and environmental concerns in the artroom. This article presents a lesson that encourages students to investigate their local environment and take photos…

Lott, Debra

2010-01-01

463

Rhotrix Vector Spaces  

ERIC Educational Resources Information Center

|By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…

Aminu, Abdulhadi

2010-01-01

464

Space research and SPARTAN  

Microsoft Academic Search

For a number of years, space research has been primarily conducted with sounding rockets and orbiting satellites. The use of satellites has disadvantages related to cost and the long lead time from design to launch, while a drawback in the case of sounding rockets is the short flight time of only a few minutes. The development of the Shuttle led

R. G. Cruddace; G. G. Fritz; D. J. Shrewsberry

1985-01-01

465

Superluminal Space Craft  

Microsoft Academic Search

Space exploration would be aided by superluminal travel. Recent publications and symposia have shown an increasing number of articles discussing superluminal travel. This argues that perhaps more serious attention might be given to suggestions or predictions of how such speeds might be obtained. Predictions of superluminal travel must address at least two things. First, a means of circumventing widely believed

Pharis E. Williams

2009-01-01

466

Propellant depot in space  

US Patent & Trademark Office Database

A space transportation propellant depot has multiple locations, sources and capabilities. Maximizing known mature technologies coupled with realistic industrial techniques results in the incremental development of a propellant source on the moon. Propellant depots are economically driven locations with defined services, sources of propellant and innovation in the pursuit of transportation related commerce as mankind explores for resources beyond Earth.

Taylor; Thomas C. (Las Cruces, NM); Kistler; Walter P. (Bellevue, WA); Citron; Robert A. (Bellevue, WA)

2009-07-14

467

SPACE BASED INTERCEPTOR SCALING  

Microsoft Academic Search

Space Based Interceptor (SBI) have ranges that are adequate to address rogue ICBMs. They are not overly sensitive to 30-60 s delay times. Current technologies would support boost phase intercept with about 150 interceptors. Higher acceleration and velocity could reduce than number by about a factor of 3 at the cost of heavier and more expensive Kinetic Kill Vehicles (KKVs).

G. CANAVAN

2001-01-01

468

Space Shuttle Missions Summary.  

National Technical Information Service (NTIS)

This document was originally produced as an informal Mission Operations book and has been updated since Space Shuttle Flight STS-1 and throughout the program. This version is a formally released NASA document. It is a handy reference guide for flight data...

F. V. Bennett R. D. Legler

2011-01-01

469

The SPACE Legacy  

ERIC Educational Resources Information Center

The SPACE (Science Processes and Concept Exploration) project began 21 years ago, just ahead of the National Curriculum. It was a research project whose findings and processes were built into the Nuffield Primary Science classroom guides for teachers, making these the best example of research-informed curriculum materials at the primary level.…

Harlen, Wynne

2007-01-01

470

Space Camp Scholarship Contest  

NSDL National Science Digital Library

Resources for those students interested in space exploration. This page produced by the Air Force Assocation lists grant and scholarship information for you and your students. The Air Force Association (AFA) is "an independent, nonprofit, civilian education organization promoting public understanding of aerospace power and the pivotal role it plays in the security of the nation."

471

Melancholic Space Age Anniversary.  

National Technical Information Service (NTIS)

This essay reflects on the future of space exploration. The percentages of world wide funding is also reviewed. Noting that few young people noted the importance of the anniversary of the launch of Sputnik, the hope for continued major funding as a reflec...

W. A. McDougall

2008-01-01

472

National Department of Space.  

National Technical Information Service (NTIS)

Man has always been fascinated by the heavens. Not until late in the 19th and early 20th Centuries did man finally have the technology to reach the moon. Currently, the heavens abound with satellites as well as a manned space station. Throughout the past ...

K. M. Shaffer

2008-01-01

473

SHIELDING AGAINST SPACE RADIATION  

Microsoft Academic Search

A discussion of the problems in space radiation shielding is presented. ; The problem of penetrating protons is considered in an attempt to iliustrate the ; physical shieiding requirements for manned vehicles and to illuminate some of the ; gaps in present knowledge. Material and magnetic shielding are considered. ; (C.E.S.);

Madey

1963-01-01

474

Shielding from space radiations  

Microsoft Academic Search

Progress during the period of 1 Jun. - 1 Dec. 1991 is presented. An analytical solution to heavy ion transport equation in terms of Green's function formalism is developed. The mathematical development is recasted into efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of extending the Green's function over the solution

C. Ken Chang; Forooz F. Badavi

1991-01-01

475

Shielding from space radiations  

Microsoft Academic Search

This Progress Report covering the period of December 1, 1992 to June 1, 1993 presents the development of an analytical solution to the heavy ion transport equation in terms of Green's function formalism. The mathematical development results are recasted into a highly efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of

C. Ken Chang; Forooz F. Badavi; Ram K. Tripathi

1993-01-01

476

Growing Plants in Space.  

National Technical Information Service (NTIS)

The possible ways to solve the problems connected with life support systems for cosmonauts on prolonged space flights by using plants from earth are examined. The cycle of nature on earth is examined, and methods are proposed for modeling this cycle withi...

V. P. Dadykin

1972-01-01

477

Entomophagy and space agriculture  

NASA Astrophysics Data System (ADS)

Supplying food for human occupants remains one of the primary issues in engineering space habitation Evidently for long-term occupation on a distant planet it is necessary to start agriculture on site Historically humans have consumed a variety of animals and it is required to fill our nutritional need when they live in space Among many candidate group and species of animal to breed in space agriculture insects are of great interest since they have a number of advantages over mammals and other vertebrates or invertebrates About 70-75 of animal species is insects and they play an important role in materials recycle loop of terrestrial biosphere at their various niche For space agriculture we propose several insect species such as the silkworm Bombyx mori