WorldWideScience

Sample records for cosmic x-ray background

  1. Cosmic X-ray background and solitars.

    Science.gov (United States)

    Chiu, H.-Y.

    In this paper the authors has examined the observational consequences of a class of new astronomical objects proposed by Friedberg, Lee and Pang, called solitars which are degenerate vacuum states embedded with particles. A study is made to include finite temperature effect and pair creation. Quark is believed to be the only species that can exist in the interior of solitars. Massive quark solitars are primarily X-ray emitters and may account for the large unexplained thermal component of the cosmic X-ray background.

  2. Interpretation of spectral paradox of cosmic X-ray background

    Institute of Scientific and Technical Information of China (English)

    李志青; 周又元

    1997-01-01

    The integrated spectrum of discrete X-ray sources (mainly the active galactic nuclei, AGN) is inconsistent with the observed spectrum of cosmic X-ray background (CXB), and it is so called CXB spectral paradox. The medium X-ray spectra of 68 AGNs are adopted, the evolution function of X-ray spectral indices is analyzed statistically, the fraction of CXB is calculated due to AGNs X-ray emission, which shows that almost 100% CXB comes from AGNs X-ray emission. Especially, the integrated spectrum in 2-10 keV is consistent with the observed spectrum of CXB. The spectral paradox of CXB can be interpreted by this result.

  3. Modelling the uv/x-ray cosmic background with CUBA

    CERN Document Server

    Haardt, F; Haardt, Francesco; Madau, Piero

    2001-01-01

    In this paper, I will describe the features of the numerical code CUBA, aimed at the solution of the radiative transfer equation in a cosmological context. CUBA will be soon available for public use at the URL http://pitto.mib.infn.it/~haardt/, allowing for several user-supplied input parameters, such as favourite cosmology, luminosity functions, Type II object evolution, stellar spectra, and many others. I will also present some new results of the UV/X-ray cosmic background as produced by the observed populations of QSOs and star forming galaxies, updating and extending our previous works. The background evolution is complemented with a number of derived quantities such as the ionization and thermal state of the IGM, the HeII opacity, the HI and HeII ionization rates, and the HI, HeII and Compton heating rates.

  4. The cosmic X-ray background-IRAS galaxy correlation and the local X-ray volume emissivity

    Science.gov (United States)

    Miyaji, Takamitsu; Lahav, Ofer; Jahoda, Keith; Boldt, Elihu

    1994-01-01

    We have cross-correlated the galaxies from the IRAS 2 Jy redshift survey sample and the 0.7 Jy projected sample with the all-sky cosmic X-ray background (CXB) map obtained from the High Energy Astronomy Observatory (HEAO) 1 A-2 experiment. We have detected a significant correlation signal between surface density of IRAS galaxies and the X-ray background intensity, with W(sub xg) = (mean value of ((delta I)(delta N)))/(mean value of I)(mean value of N)) of several times 10(exp -3). While this correlation signal has a significant implication for the contribution of the local universe to the hard (E greater than 2 keV) X-ray background, its interpretation is model-dependent. We have developed a formulation to model the cross-correlation between CXB surface brightness and galaxy counts. This includes the effects of source clustering and the X-ray-far-infrared luminosity correlation. Using an X-ray flux-limited sample of active galactic nuclei (AGNs), which has IRAS 60 micrometer measurements, we have estimated the contribution of the AGN component to the observed CXB-IRAS galaxy count correlations in order to see whether there is an excess component, i.e., contribution from low X-ray luminosity sources. We have applied both the analytical approach and Monte Carlo simulations for the estimations. Our estimate of the local X-ray volume emissivity in the 2-10 keV band is rho(sub x) approximately = (4.3 +/- 1.2) x 10(exp 38) h(sub 50) ergs/s/cu Mpc, consistent with the value expected from the luminosity function of AGNs alone. This sets a limit to the local volume emissivity from lower luminosity sources (e.g., star-forming galaxies, low-ionization nuclear emission-line regions (LINERs)) to rho(sub x) less than or approximately = 2 x 10(exp 38) h(sub 50) ergs/s/cu Mpc.

  5. Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

    CERN Document Server

    Madau, Piero

    2016-01-01

    We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct HeI photoionizations are the main source of IGM ...

  6. The Nature of the Unresolved Extragalactic Cosmic Soft X-Ray Background

    Science.gov (United States)

    Cappelluti, N.; Ranalli, P.; Roncarelli, M.; Arevalo, P.; Zamorani, G.; Comastri, A.; Gilli, R.; Rovilos, E.; Vignali, C.; Allevato, V.; hide

    2013-01-01

    In this paper we investigate the power spectrum of the unresolved 0.5-2 keV cosmic X-ray background (CXB) with deep Chandra 4-Msec (Ms) observations in the Chandra Deep Field South (CDFS). We measured a signal that, on scales >30 arcsec, is significantly higher than the shot noise and is increasing with angular scale. We interpreted this signal as the joint contribution of clustered undetected sources like active galactic nuclei (AGN), galaxies and the intergalactic medium (IGM). The power of unresolved cosmic source fluctuations accounts for approximately 12 per cent of the 0.5-2 keV extragalactic CXB. Overall, our modelling predicts that approximately 20 per cent of the unresolved CXB flux is produced by low-luminosity AGN, approximately 25 per cent by galaxies and approximately 55 per cent by the IGM. We do not find any direct evidence of the so-called 'warm hot intergalactic medium' (i.e. matter with 10(exp 5) less than T less than 10(exp 7) K and density contrast delta less than 1000), but we estimated that it could produce about 1/7 of the unresolved CXB. We placed an upper limit on the space density of postulated X-ray-emitting early black holes at z greater than 7.5 and compared it with supermassive black hole evolution models.

  7. Mildly obscured active galaxies and the cosmic X-ray background

    CERN Document Server

    Esposito, Valentino

    2016-01-01

    The diffuse cosmic X-ray background (CXB) is the sum of the emission of discrete sources, mostly massive black-holes accreting matter in active galactic nuclei (AGN). The CXB spectrum differs from the integration of the spectra of individual sources, calling for a large population, undetected so far, of strongly obscured Compton thick AGN. Such objects are predicted by unified models, which attribute most of the AGN diversity to their inclination on the line of sight, and play an important role for the understanding of the growth of black holes in the early Universe. The fraction of obscured AGN at low redshift can be derived from the observed CXB spectrum assuming AGN spectral templates and luminosity functions. We show that high signal-to-noise average hard X-ray spectra, derived from more than a billion seconds of effective exposure time with the Swift/BAT instrument, imply that mildly obscured Compton thin AGN feature a strong reflection and contribute massively to the CXB. A population of Compton thick A...

  8. Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Madejski, Grzegorz M. [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Rikkyo Univ., Tokyo (Japan). Dept. of Physics

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once the future hard X-ray all sky satellites achieve the sensitivity better than 10-12 erg/cm2/s-1 at 10-30 keV or 30-50 keV - although this is beyond the sensitivities of current hard X-ray all sky monitors - angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  9. Probing the cosmic x-ray and MeV gamma ray background radiation through the anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States); Madejski, Grzegorz M. [Stanford Univ., CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States); Rikkyo Univ., Tokyo (Japan)

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once future hard X-ray all sky satellites achieve a sensitivity better than 10–12 erg cm–2 s–1 at 10-30 keV or 30-50 keV—although this is beyond the sensitivities of current hard X-ray all sky monitors—angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  10. Soft X-ray excess in the Coma cluster from a Cosmic Axion Background

    Energy Technology Data Exchange (ETDEWEB)

    Angus, Stephen; Conlon, Joseph P.; Marsh, M.C. David; Powell, Andrew J.; Witkowski, Lukas T., E-mail: stephen.angus@physics.ox.ac.uk, E-mail: j.conlon1@physics.ox.ac.uk, E-mail: david.marsh1@physics.ox.ac.uk, E-mail: andrew.powell2@physics.ox.ac.uk, E-mail: l.witkowski@thphys.uni-heidelberg.de [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2014-09-01

    We show that the soft X-ray excess in the Coma cluster can be explained by a cosmic background of relativistic axion-like particles (ALPs) converting into photons in the cluster magnetic field. We provide a detailed self-contained review of the cluster soft X-ray excess, the proposed astrophysical explanations and the problems they face, and explain how a 0.1- 1 keV axion background naturally arises at reheating in many string theory models of the early universe. We study the morphology of the soft excess by numerically propagating axions through stochastic, multi-scale magnetic field models that are consistent with observations of Faraday rotation measures from Coma. By comparing to ROSAT observations of the 0.2- 0.4 keV soft excess, we find that the overall excess luminosity is easily reproduced for g{sub aγγ} ∼ 2 × 10{sup -13} Ge {sup -1}. The resulting morphology is highly sensitive to the magnetic field power spectrum. For Gaussian magnetic field models, the observed soft excess morphology prefers magnetic field spectra with most power in coherence lengths on O(3 kpc) scales over those with most power on O(12 kpc) scales. Within this scenario, we bound the mean energy of the axion background to 50 eV∼< ( E{sub a} ) ∼< 250 eV, the axion mass to m{sub a} ∼< 10{sup -12} eV, and derive a lower bound on the axion-photon coupling g{sub aγγ} ∼> √(0.5/Δ N{sub eff}) 1.4 × 10{sup -13} Ge {sup -1}.

  11. Cosmic X-ray Physics: Sounding rocket investigations of the diffuse X-ray background, including instrument development

    Science.gov (United States)

    McCammon, Dan

    We propose an investigation to improve our understanding of the Galactic diffuse X-ray background. The ultimate purpose of this is to determine the role of hot phases of the interstellar medium in mediating stellar feedback in star formation, in transport of metals, and in determining the structure and evolution of the Galaxy. It directly addresses SMD's astrophysics goal No. 2, to explore the origin and evolution of the galaxies, stars and planets that make up our universe. This work will involve a flight of an existing payload with small modifications in Woomera, South Australia, to observe the Galactic soft X-ray bulge and attempt to determine its nature and emission mechanisms. This flight should also either confirm or put strict upper limits on the "sterile neutrino" model for the 3.5 keV signal observed near the Galactic Center by XMM-Newton. Our investigation includes the development of thermal detectors with superconducting transition edge thermometers capable of 1-2 eV FWHM energy resolution in the 100-400 eV range with the intent of obtaining a scientifically useful spectrum on a sounding rocket flight of the emission from one million degree gas in this energy range. This will require a total area of 1-2 square centimeters for the detector array. To enable routine testing of such detectors in the lab and for necessary in-flight gain and resolution monitoring, we are trying to develop a pulsed-UV laser calibration source. In collaboration with Goddard Space Flight Center, we are investigating the practicality of waveguide-below-cutoff filters to provide the necessary attenuation of infrared radiation for these detectors while still allowing good x-ray transmission below 150 eV. The detectors, calibration source, filters, optimal high-rate pulse analysis and flight experience with the detector readouts are all relevant to future NASA major missions. The detectors we're working on for a low-energy sounding rocket flight would be an excellent match to what is

  12. X-Ray Ccds for Space Applications: Calibration, Radiation Hardness, and Use for Measuring the Spectrum of the Cosmic X-Ray Background

    Science.gov (United States)

    Gendreau, Keith Charles

    1995-01-01

    This thesis has two distinct components. One concerns the physics of the high energy resolution X-ray charge coupled devices (CCD) detectors used to measure the cosmic X-ray background (XRB) spectrum. The other involves the measurements and analysis of the XRB spectrum and instrumental background with these detectors on board the advanced satellite for cosmology and astrophysics (ASCA). The XRB has a soft component and a hard component divided at ~2 keV. The hard component is extremely isotropic, suggesting a cosmological origin. The soft component is extremely anisotropic. A galactic component most likely dominates the soft band with X-ray line emission due to a hot plasma surrounding the solar system. ASCA is one of the first of a class of missions designed to overlap the hard and soft X-ray bands. The X-ray CCD's energy resolution allows us to spectrally separate the galactic and cosmological components. Also, the resolution offers the ability to test several specific cosmological models which would make up the XRB. I have concentrated on models for the XRB origin which include active galactic nuclei (AGN) as principal components. I use ASCA data to put spectral constraints on the AGN synthesis model for the XRB. The instrumental portion of this thesis concerns the development and calibration of the X-ray CCDs. I designed, built and operated an X-ray calibration facility for these detectors. It makes use of a reflection grating spectrometer to measure absolute detection efficiency, characteristic absorption edge strengths, and spectral redistribution in the CCD response function. Part of my thesis research includes a study of radiation damage mechanisms in CCDs. This work revealed radiation damage-induced degradation in the spectral response to X-rays. It also uncovered systematic effects which affect both data analysis and CCD design. I have developed a model involving trap energy levels in the CCD band gap structure. These traps reduce the efficiency in which

  13. Analysis of the new INTEGRAL Earth observations to measure the cosmic X-ray background

    CERN Document Server

    Türler, M; Pavan, L; Ferrigno, C; Bordas, P

    2013-01-01

    A new series of Earth occultation observations has been started in 2012 to refine the determination of the cosmic X-ray background by the INTEGRAL mission. We show here that the new detector lightcurves in the 3 to 160 keV range differ from the ones obtained in 2006. Instead of the expected modulation induced by the passage of the Earth through the field of view of the JEM-X, IBIS/ISGRI and SPI instruments, we record unrelated variability on shorter timescales. We discuss the differences obtained with the datasets of 2006 and 2012 in view of the changes in pointing direction, spacecraft orbit and solar cycle phase. We conclude that the Earth occultation signal in 2012 is likely blended by radioactive decay resulting from the activation of the spacecraft when crossing the proton radiation belt at perigee passage. The observed variability, on the other hand, results most likely from the current solar maximum. In addition to a variable particle environment from inhomogeneities of the solar wind, we also find evi...

  14. The Nustar Extragalactic Surveys: The Number Counts of Active Galactic Nuclei and the Resolved Fraction of the Cosmic X-Ray Background

    DEFF Research Database (Denmark)

    Harrison, F. A.; Aird, J.; Civano, F.;

    2016-01-01

    cm-2 ≤ 10-12, a factor ∼100 fainter than previous measurements. The 8–24 keV number counts match predictions from AGN populationsynthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferredfrom the shape of the integrated cosmic X-ray background...

  15. The Chandra Deep Field-North Survey and the Cosmic X-ray Background

    CERN Document Server

    Brandt, W N; Bauer, F E; Hornschemeier, A E

    2002-01-01

    Chandra has performed a 1.4 Ms survey centred on the Hubble Deep Field-North (HDF-N), probing the X-ray Universe 55-550 times deeper than was possible with pre-Chandra missions. We describe the detected point and extended X-ray sources and discuss their overall multiwavelength (optical, infrared, submillimeter, and radio) properties. Special attention is paid to the HDF-N X-ray sources, luminous infrared starburst galaxies, optically faint X-ray sources, and high-to-extreme redshift AGN. We also describe how stacking analyses have been used to probe the average X-ray emission properties of normal and starburst galaxies at cosmologically interesting distances. Finally, we discuss plans to extend the survey and argue that a 5-10 Ms Chandra survey would lay key groundwork for future missions such as XEUS and Generation-X.

  16. Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds

    Science.gov (United States)

    Cappelluti, N.; Arendt, R.; Kashlinsky, A.; Li, Y.; Hasinger, G.; Helgason, K.; Urry, M.; Natarajan, P.; Finoguenov, A.

    2017-09-01

    We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer-IRAC cosmic infrared background and Chandra-ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg2. We report the first (>5σ) detection of a cross-power signal on large angular scales >20″ between [0.5–2] keV and the 3.6 and 4.5 μm bands, at ∼5σ and 6.3σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.

  17. Infrared-faint radio sources: a cosmological view. AGN number counts, the cosmic X-ray background and SMBH formation

    Science.gov (United States)

    Zinn, P.-C.; Middelberg, E.; Ibar, E.

    2011-07-01

    Context. Infrared-faint radio sources (IFRS) are extragalactic emitters clearly detected at radio wavelengths but barely detected or undetected at optical and infrared wavelengths, with 5σ sensitivities as low as 1 μJy. Aims: Spectral energy distribution (hereafter SED) modelling and analyses of their radio properties indicate that IFRS are consistent with a population of (potentially extremely obscured) high-redshift AGN at 3 ≤ z ≤ 6. We demonstrate some astrophysical implications of this population and compare them to predictions from models of galaxy evolution and structure formation. Methods: We compiled a list of IFRS from four deep extragalactic surveys and extrapolated the IFRS number density to a survey-independent value of (30.8 ± 15.0) deg-2. We computed the IFRS contribution to the total number of AGN in the Universe to account for the cosmic X-ray background. By estimating the black hole mass contained in IFRS, we present conclusions for the SMBH mass density in the early universe and compare it to relevant simulations of structure formation after the Big Bang. Results: The number density of AGN derived from the IFRS density was found to be ~310 deg-2, which is equivalent to a SMBH mass density of the order of 103 M⊙ Mpc-3 in the redshift range 3 ≤ z ≤ 6. This produces an X-ray flux of 9 × 10-16 W m-2 deg-2 in the 0.5-2.0 keV band and 3 × 10-15 W m-2 deg-2 in the 2.0-10 keV band, in agreement with the missing unresolved components of the Cosmic X-ray Background. To address SMBH formation after the Big Bang we invoke a scenario involving both halo gas accretion and major mergers.

  18. INTEGRAL observations of the cosmic X-ray background in the 5-100 keV range via occultation by the Earth

    DEFF Research Database (Denmark)

    Churazov, E.; Sunyaev, R.; Revnivtsev, M.

    2007-01-01

    due to occultation of extragalactic objects by the Earth disk was used to obtain the spectrum of the Cosmic X-ray Background ( CXB). Various sources of contamination were evaluated, including compact sources, Galactic Ridge emission, CXB reflection by the Earth atmosphere, cosmic ray induced emission...

  19. Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background

    CERN Document Server

    Haardt, Francesco

    2011-01-01

    We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from obscured and unobscured quasars; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted HI and HeII photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Lya forest, and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosm...

  20. Limits on the Radiative Decay of Sterile Neutrino Dark Matter from the Unresolved Cosmic and Soft X-ray Backgrounds

    CERN Document Server

    Abazajian, Kevork N; Koushiappas, S M; Hickox, R C; Abazajian, Kevork N.; Markevitch, Maxim; Koushiappas, Savvas M.; Hickox, Ryan C.

    2006-01-01

    We present upper limits on line emission in the Cosmic X-ray background (CXB) that would be produced by decay of sterile neutrino dark matter. We employ the spectra of the unresolved component of the CXB in the Chandra Deep Fields North and South obtained with the Chandra CCD detector in the E=0.8-9 keV band. The expected decay flux comes from the dark matter on the lines of sight through the Milky Way galactic halo. Our constraints on the sterile neutrino decay rate are sensitive to the modeling of the Milky Way halo. The highest halo mass estimates provide a limit on the sterile neutrino mass of m_s<2.9 keV in the Dodelson-Widrow production model, while the lowest halo mass estimates provide the conservative limit of m_s<5.7 keV (2-sigma). We also discuss constraints from a short observation of the softer (E<1 keV) X-ray background with a rocket-borne calorimeter by McCammon and collaborators.

  1. Limits on the radiative decay of sterile neutrino dark matter from the unresolved cosmic and soft x-ray backgrounds

    Science.gov (United States)

    Abazajian, Kevork N.; Markevitch, Maxim; Koushiappas, Savvas M.; Hickox, Ryan C.

    2007-03-01

    We present upper limits on line emission in the Cosmic X-ray background (CXB) that would be produced by decay of sterile neutrino dark matter. We employ the spectra of the unresolved component of the CXB in the Chandra Deep Fields North and South obtained with the Chandra CCD detector in the E=0.8 9keV band. The expected decay flux comes from the dark matter on the lines of sight through the Milky Way galactic halo. Our constraints on the sterile neutrino decay rate are sensitive to the modeling of the Milky Way halo. The highest halo mass estimates provide a limit on the sterile neutrino mass of msrocket-borne calorimeter by McCammon and collaborators.

  2. A re-consideration of the HEAO-1 A2 Measurements of the Cosmic X-ray Background Surface Brightness

    Science.gov (United States)

    Jahoda, K.

    2005-12-01

    The HEAO-1 A2 experiment was designed to make high precision and low systematics measurements of the Cosmic X-ray Background from 0.1 - 60 keV. No subsequent experiment has been capable of similarly clean separation of cosmic and instrumental background. Most more recent measurements of the 2-10 keV surface brightness are 20% higher than values derived from the spectral parameterization of the 3-50 keV spectrum given in the original A2 analysis of Marshall et al. (1980, ApJ 235, 4 (M80)). A recent analysis of archival A2 data by Revnivtsev et al. (astro-ph/0412304 (R05)) finds a surface brightness 15-20% higher than M80, an uncomfortably large discrepancy for data taken from a single experiment. We present a third analysis of the A2 data and identify two effects neglected in the comparison of previous A2 results: (a) the extrapolation of the M80 parameterization below 3 keV fails to describe the data; (b) R05 uses an unabsorbed, and high, value for the flux from the Crab nebula plus pulsar which results in a high value for the inferred count rate to CXB surface brightness conversion. Correcting for these effects, our best estimate of the 2-10 keV surface brightness is 1.84 × 10-11 ergs cm-2 s-1 deg-2 on a flux scale where the (absorbed) 2-10 Crab flux is 2.32 × 10-8 ergs cm-2 s-1. This value is only about 10% below the average compiled by Moretti et al. (2003, ApJ, 588, 696). We discuss how well the X-ray brightness of the Crab, to which this measurement is normalized, is known. This research made use of data from the High Energy Astrophysics Science Archive Research Center (HEASARC), provided by NASA's Goddard Space Flight Center.

  3. Can AGN and galaxy clusters explain the surface brightness fluctuations of the cosmic X-ray background?

    Science.gov (United States)

    Kolodzig, Alexander; Gilfanov, Marat; Hütsi, Gert; Sunyaev, Rashid

    2017-04-01

    Fluctuations of the surface brightness of cosmic X-ray background (CXB) carry unique information about faint and low-luminosity source populations, which is inaccessible for conventional large-scale structure (LSS) studies based on resolved sources. We used XBOOTES (5ks deep Chandra X-ray Observatory ACIS-I maps of the ˜ 9 deg2 Bootes field of the NOAO Deep Wide-Field Survey) to conduct the most accurate measurement to date of the power spectrum of fluctuations of the unresolved CXB on the angular scales of 3 arcsec-17 arcmin. We find that at sub-arcmin angular scales, the power spectrum is consistent with the active galactic nucleus (AGN) shot noise, without much need for any significant contribution from their one-halo term. This is consistent with the theoretical expectation that low-luminosity AGN reside alone in their dark matter haloes. However, at larger angular scales, we detect a significant LSS signal above the AGN shot noise. Its power spectrum, obtained after subtracting the AGN shot noise, follows a power law with the slope of -0.8 ± 0.1 and its amplitude is much larger than what can be plausibly explained by the two-halo term of AGN. We demonstrate that the detected LSS signal is produced by unresolved clusters and groups of galaxies. For the flux limit of the XBOOTES survey, their flux-weighted mean redshift equals ˜ 0.3, and the mean temperature of their intracluster medium (ICM), ≈ 1.4 keV, corresponds to the mass of M500 ˜ 1013.5 M⊙. The power spectrum of CXB fluctuations carries information about the redshift distribution of these objects and the spatial structure of their ICM on the linear scales of up to ˜Mpc, i.e. of the order of the virial radius.

  4. The Chandra COSMOS Legacy Survey: Energy Spectrum of the Cosmic X-Ray Background and Constraints on Undetected Populations

    Science.gov (United States)

    Cappelluti, Nico; Li, Yanxia; Ricarte, Angelo; Agarwal, Bhaskar; Allevato, Viola; Tasnim Ananna, Tonima; Ajello, Marco; Civano, Francesca; Comastri, Andrea; Elvis, Martin; Finoguenov, Alexis; Gilli, Roberto; Hasinger, Günther; Marchesi, Stefano; Natarajan, Priyamvada; Pacucci, Fabio; Treister, E.; Urry, C. Megan

    2017-03-01

    Using Chandra observations in the 2.15 deg2 COSMOS-legacy field, we present one of the most accurate measurements of the Cosmic X-ray Background (CXB) spectrum to date in the [0.3–7] keV energy band. The CXB has three distinct components: contributions from two Galactic collisional thermal plasmas at kT ∼ 0.27 and 0.07 keV and an extragalactic power law with a photon spectral index Γ = 1.45 ± 0.02. The 1 keV normalization of the extragalactic component is 10.91 ± 0.16 keV cm‑2 s‑1 sr‑1 keV‑1. Removing all X-ray-detected sources, the remaining unresolved CXB is best fit by a power law with normalization 4.18 ± 0.26 keV cm‑2 s‑1 sr‑1 keV‑1 and photon spectral index Γ = 1.57 ± 0.10. Removing faint galaxies down to {i}{AB}∼ 27{--}28 leaves a hard spectrum with {{Γ }}∼ 1.25 and a 1 keV normalization of ∼1.37 keV cm‑2 s‑1 sr‑1 keV‑1. This means that ∼91% of the observed CXB is resolved into detected X-ray sources and undetected galaxies. Unresolved sources that contribute ∼8%–9% of the total CXB show marginal evidence of being harder and possibly more obscured than resolved sources. Another ∼1% of the CXB can be attributed to still undetected star-forming galaxies and absorbed active galactic nuclei. According to these limits, we investigate a scenario where early black holes totally account for non-source CXB fraction and constrain some of their properties. In order to not exceed the remaining CXB and the z∼ 6 accreted mass density, such a population of black holes must grow in Compton-thick envelopes with {N}H > 1.6 × 1025 cm‑2 and form in extremely low-metallicity environments ({Z}ȯ )∼ {10}-3.

  5. Can AGN and galaxy clusters explain the surface brightness fluctuations of the cosmic X-ray background?

    CERN Document Server

    Kolodzig, Alexander; Hütsi, Gert; Sunyaev, Rashid

    2016-01-01

    Fluctuations of the surface brightness of cosmic X-ray background (CXB) carry unique information about faint and low luminosity source populations, which is inaccessible for conventional large-scale structure (LSS) studies based on resolved sources. We used Chandra data of the XBOOTES field ($\\sim9\\,\\mathrm{deg^2}$) to conduct the most accurate measurement to date of the power spectrum of fluctuations of the unresolved CXB on the angular scales of $\\sim3\\,$arcsec $-$ $\\sim17\\,$arcmin. We find that at sub-arcmin angular scales, the power spectrum is consistent with the AGN shot noise, without much need for any significant contribution from their one-halo term. This is consistent with the theoretical expectation that low-luminosity AGN reside alone in their dark matter halos. However, at larger angular scales we detect a significant LSS signal above the AGN shot noise. Its power spectrum, obtained after subtracting the AGN shot noise, follows a power law with the slope of $-0.8\\pm0.1$ and its amplitude is much ...

  6. Infrared-Faint Radio Sources: A Cosmological View - AGN Number Counts, the Cosmic X-Ray Background and SMBH Formation

    CERN Document Server

    Zinn, Peter-Christian; Ibar, Edo

    2011-01-01

    Context. Infrared Faint Radio Sources (IFRS) are extragalactic emitters clearly detected at radio wavelengths but barely detected or undetected at optical and infrared wavelengths, with 5 sigma sensitivities as low as 1 uJy. Aims. Recent SED-modelling and analysis of their radio properties shows that IFRS are consistent with a population of (potentially extremely obscured) high-redshift AGN at 3Cosmic X-ray Background. By estimating the black hole mass contained in IFRS, we present conclusions for the SMBH mass density in the early universe and compare it to relevant simula...

  7. Cross-correlating Cosmic IR and X-ray Background Fluctuations: Evidence of Significant Black Hole Populations Among the CIB Sources

    Science.gov (United States)

    Cappelluti, N.; Kashlinsky, A.; Arendt, R. G.; Comastri, A.; Fazio, G. G.; Finoguenov, A.; Hasinger, G.; Mather, J. C.; Miyaji, T; Moseley, S. H.

    2013-01-01

    In order to understand the nature of the sources producing the recently uncovered cosmic infrared background (CIB) fluctuations, we study cross-correlations between the fluctuations in the source-subtracted CIB from Spitzer/IRAC data and the unresolved cosmic X-ray background from deep Chandra observations. Our study uses data from the EGS/AEGIS field, where both data sets cover an approx = 8' x 45' region of the sky. Our measurement is the cross-power spectrum between the IR and X-ray data. The cross-power signal between the IRAC maps at 3.6 micron and 4.5 micron and the Chandra [0.5-2] keV data has been detected, at angular scales approx >20'', with an overall significance of approx = 3.8 sigma and approx. = 5.6 sigma, respectively. At the same time we find no evidence of significant cross-correlations at the harder Chandra bands. The cross-correlation signal is produced by individual IR sources with 3.6 micron and 4.5 micron magnitudes m(sub AB) approx. > 25-26 and [0.5-2] keV X-ray fluxes populations. We discuss the various possible origins for the cross-power signal and show that neither local foregrounds nor the known remaining normal galaxies and active galactic nuclei can reproduce the measurements. These observational results are an important new constraint on theoretical modeling of the near-IR CIB fluctuations. local foregrounds, nor the known remaining normal galaxies and active galactic nuclei (AGN) can reproduce the measurements. These observational results are an important new constraint on theoretical modeling of the near-IR CIB fluctuations

  8. The NuSTAR Extragalactic Surveys: The Number Counts of Active Galactic Nuclei and the Resolved Fraction of the Cosmic X-Ray Background

    Science.gov (United States)

    Harrison, F. A.; Aird, J.; Civano, F.; Lansbury, G.; Mullaney, J. R.; Ballantyne, D. R.; Alexander, D. M.; Stern, D.; Ajello, M.; Barret, D.; Bauer, F. E.; Baloković, M.; Brandt, W. N.; Brightman, M.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Del Moro, A.; Forster, K.; Gandhi, P.; Giommi, P.; Grefenstette, B. W.; Hailey, C. J.; Hickox, R. C.; Hornstrup, A.; Kitaguchi, T.; Koglin, J.; Luo, B.; Madsen, K. K.; Mao, P. H.; Miyasaka, H.; Mori, K.; Perri, M.; Pivovaroff, M.; Puccetti, S.; Rana, V.; Treister, E.; Walton, D.; Westergaard, N. J.; Wik, D.; Zappacosta, L.; Zhang, W. W.; Zoglauer, A.

    2016-11-01

    We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGNs) identified in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys. NuSTAR has now resolved 33%-39% of the X-ray background in the 8-24 keV band, directly identifying AGNs with obscuring columns up to ˜ {10}25 {{cm}}-2. In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range 5× {10}-15 ≲ S(3-8 keV)/{erg} {{{s}}}-1 {{cm}}-2 ≲ {10}-12 probed by NuSTAR. In the hard 8-24 keV band NuSTAR probes fluxes over the range 2× {10}-14 ≲ S(8-24 keV)/{erg} {{{s}}}-1 {{cm}}-2 ≲ {10}-12, a factor ˜100 fainter than previous measurements. The 8-24 keV number counts match predictions from AGN population synthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferred from the shape of the integrated cosmic X-ray background. The measured NuSTAR counts lie significantly above simple extrapolation with a Euclidian slope to low flux of the Swift/BAT 15-55 keV number counts measured at higher fluxes (S(15-55 keV) ≳ 10-11 {erg} {{{s}}}-1 {{cm}}-2), reflecting the evolution of the AGN population between the Swift/BAT local (z\\lt 0.1) sample and NuSTAR’s z˜ 1 sample. CXB synthesis models, which account for AGN evolution, lie above the Swift/BAT measurements, suggesting that they do not fully capture the evolution of obscured AGNs at low redshifts.

  9. The Contribution of z < or Approx. 6 Sources to the Spatial Coherence in the Unresolved Cosmic Near-Infrared and X-Ray Backgrounds

    Science.gov (United States)

    Helgason, K.; Cappelluti, N.; Hasinger, G.; Kashlinsky, A.; Ricotti, M.

    2014-01-01

    A spatial clustering signal has been established in Spitzer/IRAC measurements of the unresolved cosmic near-infrared background (CIB) out to large angular scales, approx. 1deg. This CIB signal, while significantly exceeding the contribution from the remaining known galaxies, was further found to be coherent at a highly statistically significant level with the unresolved soft cosmic X-ray background (CXB). This measurement probes the unresolved CXB to very faint source levels using deep near-IR source subtraction.We study contributions from extragalactic populations at low to intermediate redshifts to the measured positive cross-power signal of the CIB fluctuations with the CXB. We model the X-ray emission from active galactic nuclei (AGNs), normal galaxies, and hot gas residing in virialized structures, calculating their CXB contribution including their spatial coherence with all infrared emitting counterparts. We use a halo model framework to calculate the auto and cross-power spectra of the unresolved fluctuations based on the latest constraints of the halo occupation distribution and the biasing of AGNs, galaxies, and diffuse emission. At small angular scales (1), the 4.5microns versus 0.5-2 keV coherence can be explained by shot noise from galaxies and AGNs. However, at large angular scales (approx.10), we find that the net contribution from the modeled populations is only able to account for approx. 3% of the measured CIB×CXB cross-power. The discrepancy suggests that the CIB×CXB signal originates from the same unknown source population producing the CIB clustering signal out to approx. 1deg.

  10. X-Ray Background from Early Binaries

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    What impact did X-rays from the first binary star systems have on the universe around them? A new study suggests this radiation may have played an important role during the reionization of our universe.Ionizing the UniverseDuring the period of reionization, the universe reverted from being neutral (as it was during recombination, the previous period)to once again being ionized plasma a state it has remained in since then. This transition, which occurred between 150 million and one billion years after the Big Bang (redshift of 6 z 20), was caused by the formation of the first objects energetic enough to reionize the universes neutral hydrogen.ROSAT image of the soft X-ray background throughout the universe. The different colors represent different energy bands: 0.25 keV (red), 0.75 keV (green), 1.5 keV (blue). [NASA/ROSAT Project]Understanding this time period in particular, determining what sources caused the reionization, and what the properties were of the gas strewn throughout the universe during this time is necessary for us to be able to correctly interpret cosmological observations.Conveniently, the universe has provided us with an interesting clue: the large-scale, diffuse X-ray background we observe all around us. What produced these X-rays, and what impact did this radiation have on the intergalactic medium long ago?The First BinariesA team of scientists led by Hao Xu (UC San Diego) has suggested that the very first generation of stars might be an important contributor to these X-rays.This hypothetical first generation, Population III stars, are thought to have formed before and during reionization from large clouds of gas containing virtually no metals. Studies suggest that a large fraction of Pop III stars formed in binaries and when those stars ended their lives as black holes, ensuing accretion from their companions could produceX-ray radiation.The evolution with redshift of the mean X-ray background intensities. Each curve represents a different

  11. The NuSTAR extragalactic survey: a first sensitive look at the high-energy cosmic x-ray background population

    DEFF Research Database (Denmark)

    Alexander, D. M.; Stern, D.; Del Moro, A.;

    2013-01-01

    of broad-band ≈ 0.5-32 keV spectroscopy, optical spectroscopy, and broad-band ultraviolet-to-mid-infrared spectral energy distribution analyses. We find that the dominant source population is quasars with L10-40 keV > 1044 erg s-1, of which ≈ 50% are obscured with NH ≳ 1022 cm-2. However, none of the 10 NuSTAR......We report on the first 10 identifications of sources serendipitously detected by the Nuclear Spectroscopic Telescope Array ( NuSTAR ) to provide the first sensitive census of the cosmic X-ray background source population at ≳ 10 keV. We find that these NuSTAR -detected sources are ≈ 100 times...... times higher than the median stellar mass of nearby high-energy selected AGNs, which may be at least partially driven by the order of magnitude higher X-ray luminosities of the NuSTAR sources. Within the low source-statistic limitations of our study, our results suggest that the overall properties...

  12. Preliminary background prediction for the INTEGRAL x-ray monitor

    DEFF Research Database (Denmark)

    Feroci, M.; Costa, E.; Budtz-Joergensen, C.;

    1996-01-01

    The JEM-X (joint European x-ray monitor) experiment will be flown onboard the ESA's INTEGRAL satellite. The instrumental background level of the two JEM-X twin detectors will depend on several parameters, among which the satellite orbit and mass distribution, and the detectors materials play...... a major role. Based on the information available at the present stage of the emission design, we have computed the instrumental background to be expected because of two main background components: direct diffuse x-ray background and secondary photons originated by the interactions of the primary cosmic...... rays with the spacecraft structures. This calculation has been carried out by means of a Monte Carlo simulation using the code MCNP. The background due to on- orbit material activation and to the primary cosmic rays direct interactions with the detecting medium has not been considered. The INTEGRAL...

  13. Complete Hard X-Ray Surveys, AGN Luminosity Functions and the X-Ray Background

    Science.gov (United States)

    Tueller, Jack

    2011-01-01

    AGN are believed to make up most of the Cosmic X-Ray Background (CXB) above a few keV, but this background cannot be fully resolved at energies less than 10 keV due to absorption. The Swift/BAT and INTEGRAL missions are performing the first complete hard x-ray surveys with minimal bias due to absorption. The most recent results for both missions will be presented. Although the fraction of the CXB resolved by these surveys is small, it is possible to derive unbiased number counts and luminosity functions for AGN in the local universe. The survey energy range from 15-150 keV contains the important reflection and cutoff spectral features dominate the shape of the AGN contribution to the CXB. Average spectral characteristics of survey detected AGN will be presented and compared with model distributions. The numbers of hard x-ray blazars detected in these surveys are finally sufficient to estimate this important component's contribution the cosmic background. Constraints on CXB models and their significance will be discussed.

  14. The NuSTAR Extragalactic Survey: A First Sensitive Look at the High-Energy Cosmic X-Ray Background Population

    Science.gov (United States)

    Alexander, D. M.; Stern, D.; DelMoro, A.; Lansbury, G. B.; Assef, R. J.; Aird, J.; Ajello, M.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; hide

    2013-01-01

    We report on the first 10 identifications of sources serendipitously detected by the Nuclear Spectroscopic Telescope Array (NuSTAR) to provide the first sensitive census of the cosmic X-ray background source population at approximately greater than 10 keV. We find that these NuSTAR-detected sources are approximately 100 times fainter than those previously detected at approximately greater than 10 keV and have a broad range in redshift and luminosity (z = 0.020-2.923 and L(sub 10-40 keV) approximately equals 4 × 10(exp 41) - 5 × 10(exp 45) erg per second; the median redshift and luminosity are z approximately equal to 0.7 and L(sub 10-40 keV) approximately equal to 3 × 10(exp 44) erg per second, respectively. We characterize these sources on the basis of broad-band approximately equal to 0.5 - 32 keV spectroscopy, optical spectroscopy, and broad-band ultraviolet-to-mid-infrared spectral energy distribution analyses. We find that the dominant source population is quasars with L(sub 10-40 keV) greater than 10(exp 44) erg per second, of which approximately 50% are obscured with N(sub H) approximately greater than 10(exp 22) per square centimeters. However, none of the 10 NuSTAR sources are Compton thick (N(sub H) approximately greater than 10(exp 24) per square centimeters) and we place a 90% confidence upper limit on the fraction of Compton-thick quasars (L(sub 10-40 keV) greater than 10(exp 44) erg per second) selected at approximately greater than 10 keV of approximately less than 33% over the redshift range z = 0.5 - 1.1. We jointly fitted the rest-frame approximately equal to 10-40 keV data for all of the non-beamed sources with L(sub 10-40 keV) greater than 10(exp 43) erg per second to constrain the average strength of reflection; we find R less than 1.4 for gamma = 1.8, broadly consistent with that found for local active galactic nuclei (AGNs) observed at approximately greater than 10 keV. We also constrain the host-galaxy masses and find a median stellar

  15. The NuSTAR Extragalactic Surveys: The Number Counts of Active Galactic Nuclei and the Resolved Fraction of the Cosmic X-ray Background

    CERN Document Server

    Harrison, F A; Civano, F; Lansbury, G; Mullaney, J R; Ballantyne, D R; Alexander, D M; Stern, D; Ajello, M; Barret, D; Bauer, F E; Balokovic, M; Brandt, W N; Brightman, M; Boggs, S E; Christensen, F E; Comastri, A; Craig, W W; Del Moro, A; Forster, K; Gandhi, P; Giommi, P; Grefenstette, B W; Hailey, C J; Hickox, R C; Hornstrup, A; Kitaguchi, T; Koglin, J; Luo, B; Madsen, K K; Mao, P H; Miyasaka, H; Mori, K; Perri, M; Pivovaroff, M; Puccetti, S; Rana, V; Treister, E; Walton, D; Westergaard, N J; Wik, D; Zappacosta, L; Zhang, W W; Zoglauer, A

    2015-01-01

    We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGN) identified in the NuSTAR extragalactic surveys. NuSTAR has now resolved approximately 35% of the X-ray background in the 8-24 keV band, directly identifying AGN with obscuring columns up to 1e25 / cm2. In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range 5e-15 1e-11 erg/cm2/s, for any realistic AGN spectral model. The most natural explanation for the difference is an evolution in the AGN poulation between the very local objects seen by BAT and the more distant (0.5 < z < 1) NuSTAR sample that is not accounted for in the current models.

  16. Preliminary background prediction for the INTEGRAL x-ray monitor

    DEFF Research Database (Denmark)

    Feroci, M.; Costa, E.; Budtz-Joergensen, C.

    1996-01-01

    The JEM-X (joint European x-ray monitor) experiment will be flown onboard the ESA's INTEGRAL satellite. The instrumental background level of the two JEM-X twin detectors will depend on several parameters, among which the satellite orbit and mass distribution, and the detectors materials play...... rays with the spacecraft structures. This calculation has been carried out by means of a Monte Carlo simulation using the code MCNP. The background due to on- orbit material activation and to the primary cosmic rays direct interactions with the detecting medium has not been considered. The INTEGRAL...... satellite structure is only now being completely defined and the details of the instrument design are still under evolution. The present background estimation can therefore be only preliminary and based on some reasonable approximations on the radiation environment in which the INTEGRAL experiments...

  17. The LOFT (Large Observatory for X-ray Timing) background simulations

    DEFF Research Database (Denmark)

    Campana, R.; Feroci, M.; Del Monte, E.

    2012-01-01

    around compact objects. With an effective area of ~10 m2 LOFT will be able to measure very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and to optimize the instrument...... design. The two main contributions to the background are cosmic diffuse X-rays and high energy cosmic rays; also, albedo emission from the Earth is significant. These contributions to the background for both the Large Area Detector and the Wide Field Monitor are discussed, on the basis of extrensive...

  18. X-Ray Emission from Star-Forming Galaxies - Signatures of Cosmic Rays and Magnetic Fields

    CERN Document Server

    Schober, Jennifer; Klessen, Ralf S

    2014-01-01

    The evolution of magnetic fields in galaxies is still an open problem in astrophysics. In nearby galaxies the far-infrared-radio correlation indicates the coupling between magnetic fields and star formation. The correlation arises from the synchrotron emission of cosmic ray electrons traveling through the interstellar magnetic fields. However, with an increase of the interstellar radiation field (ISRF), inverse Compton scattering becomes the dominant energy loss mechanism of cosmic ray electrons with a typical emission frequency in the X-ray regime. The ISRF depends on the one hand on the star formation rate and becomes stronger in starburst galaxies, and on the other hand increases with redshift due to the evolution of the cosmic microwave background. With a model for the star formation rate of galaxies, the ISRF, and the cosmic ray spectrum, we can calculate the expected X-ray luminosity resulting from the inverse Compton emission. Except for galaxies with an active galactic nucleus the main additional cont...

  19. Low energy background in mercuric iodide X-ray spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, X.J. [TN Technol., Inc., Round Rock, TX (United States). Dept. of Anal. Instrum.; Natarajan, M. [TN Technol., Inc., Round Rock, TX (United States). Dept. of Anal. Instrum.; Henderson, J. [TN Technol., Inc., Round Rock, TX (United States). Dept. of Anal. Instrum.

    1996-10-01

    The origins of the continuous background (window effect or dead layer) in mercuric iodide X-ray spectrometers are investigated. It is found that photo-electron escape and carrier diffusion are the dominant mechanisms of incomplete charge collection in the energy range of interest (from 3-60 keV). X-ray spectra measurements, computer calculation and photo-response measurements are presented in support of the proposed model. Many observations of detector behavior made in the manufacturing and application of mercuric iodide X-ray detectors can be explained by this model. (orig.).

  20. Constraining the redshifted 21-cm signal with the unresolved soft X-ray background

    CERN Document Server

    Fialkov, Anastasia; Barkana, Rennan; Silk, Joseph

    2016-01-01

    We use the observed unresolved cosmic X-ray background (CXRB) in the soft 0.5-2 keV band to constrain the population of high redshift X-ray sources existing before the end of reionization. Because the nature of these sources is poorly understood, we consider hot gas, X-ray binaries and mini-quasars (i.e., sources with soft and hard X-ray spectra) as possible candidates. We show that all types of the considered sources naturally generate a soft band CXRB, but if they actually generate the observed background their efficiency in producing X-rays must be one-to-two orders of magnitude higher than what is normally assumed. We find that the efficiency of hard sources does not have to be increased as strongly as that of the soft ones in order to generate the observed background. In addition, we show that when models are normalized to the CXRB, cosmic heating occurs quite early, and in some cases X-rays become a significant driver of reionization competing with the UV photons, while the expected high-redshift 21-cm ...

  1. Radiative feedback from an early X-ray background

    CERN Document Server

    Glover, S C O; Glover, Simon C.O.; Brand, Peter W.J.L.

    2003-01-01

    The first generation of stars (commonly known as population III) are expected to form in low-mass protogalaxies in which molecular hydrogen is the dominant coolant. Radiation from these stars will rapidly build up an extragalactic ultraviolet background capable of photodissociating H2, and it is widely believed that this background will suppress further star formation in low-mass systems. However, star formation will also produce an extragalactic X-ray background. This X-ray background, by increasing the fractional ionization of protogalactic gas, promotes H2 formation and reduces the effectiveness of ultraviolet feedback. In this paper, we examine which of these backgrounds has the dominant effect. Using a simple model for the growth of the UV and X-ray backgrounds, together with a detailed one-dimensional model of protogalactic chemical evolution, we examine the effects of the X-ray backgrounds produced by a number of likely source models. We show that in several cases, the resulting X-ray background is str...

  2. Background X-ray Radiation Fields Produced by Young Embedded Star Clusters

    CERN Document Server

    Adams, Fred; Holden, Lisa

    2012-01-01

    Most star formation in our galaxy occurs within embedded clusters, and these background environments can affect the star and planet formation processes occurring within them. In turn, young stellar members can shape the background environment and thereby provide a feedback mechanism. This work explores one aspect of stellar feedback by quantifying the background X-ray radiation fields produced by young stellar objects. Specifically, the distributions of X-ray luminosities and X-ray fluxes produced by cluster environments are constructed as a function of cluster membership size $N$. Composite flux distributions, for given distributions of cluster sizes $N$, are also constructed. The resulting distributions are wide and the X-ray radiation fields are moderately intense, with the expected flux levels exceeding the cosmic and galactic X-ray backgrounds by factors of $\\sim10-1000$ (for energies 0.2 -- 15 keV). For circumstellar disks that are geometrically thin and optically thick, the X-ray flux from the backgrou...

  3. Chandra Resolves Cosmic X-ray Glow and Finds Mysterious New Sources

    Science.gov (United States)

    2000-01-01

    While taking a giant leap towards solving one of the greatest mysteries of X-ray astronomy, NASA's Chandra X-ray Observatory also may have revealed the most distant objects ever seen in the universe and discovered two puzzling new types of cosmic objects. Not bad for being on the job only five months. Chandra has resolved most of the X-ray background, a pervasive glow of X-rays throughout the universe, first discovered in the early days of space exploration. Before now, scientists have not been able to discern the background's origin, because no X-ray telescope until Chandra has had both the angular resolution and sensitivity to resolve it. "This is a major discovery," said Dr. Alan Bunner, Director of NASA's Structure andEvolution of the universe science theme. "Since it was first observed thirty-seven years ago, understanding the source of the X-ray background has been aHoly Grail of X-ray astronomy. Now, it is within reach." The results of the observation will be discussed today at the 195th national meeting of the American Astronomical Society in Atlanta, Georgia. An article describing this work has been submitted to the journal Nature by Dr. Richard Mushotzky, of NASA Goddard Space Flight Center, Greenbelt, Md., Drs. Lennox Cowie and Amy Barger at the University of Hawaii, Honolulu, and Dr. Keith Arnaud of the University of Maryland, College Park. "We are all very excited by this finding," said Mushotzky. "The resolution of most of the hard X-ray background during the first few months of the Chandra mission is a tribute to the power of this observatory and bodes extremely well for its scientific future," Scientists have known about the X-ray glow, called the X-ray background, since the dawn of X-ray astronomy in the early 1960s. They have been unable to discern its origin, however, for no X-ray telescope until Chandra has had both the angular resolution and sensitivity to resolve it. The German-led ROSAT mission, now completed, resolved much of the lower

  4. X-ray emission from star-forming galaxies - signatures of cosmic rays and magnetic fields

    Science.gov (United States)

    Schober, J.; Schleicher, D. R. G.; Klessen, R. S.

    2015-01-01

    The evolution of magnetic fields in galaxies is still an open problem in astrophysics. In nearby galaxies the far-infrared-radio correlation indicates the coupling between magnetic fields and star formation. The correlation arises from the synchrotron emission of cosmic ray electrons travelling through the interstellar magnetic fields. However, with an increase of the interstellar radiation field (ISRF), inverse Compton scattering becomes the dominant energy loss mechanism of cosmic ray electrons with a typical emission frequency in the X-ray regime. The ISRF depends on the one hand on the star formation rate and becomes stronger in starburst galaxies, and on the other hand increases with redshift due to the higher temperature of the cosmic microwave background. With a model for the star formation rate of galaxies, the ISRF, and the cosmic ray spectrum, we can calculate the expected X-ray luminosity resulting from the inverse Compton emission. Except for galaxies with an active galactic nucleus the main additional contribution to the X-ray luminosity comes from X-ray binaries. We estimate this contribution with an analytical model as well as with an observational relation, and compare it to the pure inverse Compton luminosity. Using data from the Chandra Deep Field Survey and far-infrared observations from Atacama Large Millimeter/Submillimeter Array, we then determine upper limits for the cosmic ray energy. Assuming that the magnetic energy in a galaxy is in equipartition with the energy density of the cosmic rays, we obtain upper limits for the magnetic field strength. Our results suggest that the mean magnetic energy of young galaxies is similar to the one in local galaxies. This points towards an early generation of galactic magnetic fields, which is in agreement with current dynamo evolution models.

  5. Constraining the redshifted 21-cm signal with the unresolved soft X-ray background

    Science.gov (United States)

    Fialkov, Anastasia; Cohen, Aviad; Barkana, Rennan; Silk, Joseph

    2017-01-01

    We use the observed unresolved cosmic X-ray background (CXRB) in the 0.5-2 keV band and existing upper limits on the 21-cm power spectrum to constrain the high-redshift population of X-ray sources, focusing on their effect on the thermal history of the Universe and the cosmic 21-cm signal. Because the properties of these sources are poorly constrained, we consider hot gas, X-ray binaries and mini-quasars (i.e. sources with soft or hard X-ray spectra) as possible candidates. We find that (1) the soft-band CXRB sets an upper limit on the X-ray efficiency of sources that existed before the end of reionization, which is one-to-two orders of magnitude higher than typically assumed efficiencies, (2) hard sources are more effective in generating the CXRB than the soft ones, (3) the commonly assumed limit of saturated heating is not valid during the first half of reionization in the case of hard sources, with any allowed value of X-ray efficiency, (4) the maximal allowed X-ray efficiency sets a lower limit on the depth of the absorption trough in the global 21-cm signal and an upper limit on the height of the emission peak, while in the 21-cm power spectrum it sets a minimum amplitude and frequency for the high-redshift peaks, and (5) the existing upper limit on the 21-cm power spectrum sets a lower limit on the X-ray efficiency for each model. When combined with the 21-cm global signal, the CXRB will be useful for breaking degeneracies and helping constrain the nature of high-redshift heating sources.

  6. Constraining the redshifted 21-cm signal with the unresolved soft X-ray background

    Science.gov (United States)

    Fialkov, Anastasia; Cohen, Aviad; Barkana, Rennan; Silk, Joseph

    2016-10-01

    We use the observed unresolved cosmic X-ray background (CXRB) in the 0.5 - 2 keV band and existing upper limits on the 21-cm power spectrum to constrain the high-redshift population of X-ray sources, focusing on their effect on the thermal history of the Universe and the cosmic 21-cm signal. Because the properties of these sources are poorly constrained, we consider hot gas, X-ray binaries and mini-quasars (i.e., sources with soft or hard X-ray spectra) as possible candidates. We find that (1) the soft-band CXRB sets an upper limit on the X-ray efficiency of sources that existed before the end of reionization, which is one-to-two orders of magnitude higher than typically assumed efficiencies, (2) hard sources are more effective in generating the CXRB than the soft ones, (3) the commonly-assumed limit of saturated heating is not valid during the first half of reionization in the case of hard sources, with any allowed value of X-ray efficiency, (4) the maximal allowed X-ray efficiency sets a lower limit on the depth of the absorption trough in the global 21-cm signal and an upper limit on the height of the emission peak, while in the 21-cm power spectrum it sets a minimum amplitude and frequency for the high-redshift peaks, and (5) the existing upper limit on the 21-cm power spectrum sets a lower limit on the X-ray efficiency for each model. When combined with the 21-cm global signal, the CXRB will be useful for breaking degeneracies and helping constrain the nature of high-redshift heating sources.

  7. K-alpha X-rays from cosmic-ray oxygen. [subrelativistic interstellar oxygen ions

    Science.gov (United States)

    Pravdo, S. H.; Boldt, E. A.

    1975-01-01

    Equilibrium charge fractions are calculated for subrelativistic cosmic-ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relation of these results to the diffuse X-ray background measured at the appropriate energy (about 0.6 keV) suggests an observable broadened line feature.

  8. The Diffuse Soft X-ray Background: Trials and Tribulations

    Science.gov (United States)

    Ulmer, Melville P.

    2013-01-01

    I joined the University of Wisconsin-Madison sounding rocket group at its inception. It was an exciting time, as nobody knew what the X-ray sky looked like. Our group focused on the soft X-ray background, and built proportional counters with super thin (2 micron thick) windows. As the inter gas pressure of the counters was about 1 atmosphere, it was no mean feat to get payload to launch without the window bursting. On top of that we built all our own software from space solutions to unfolding the spectral data. For we did it then as now: Our computer code modeled the detector response and then folded various spectral shapes through the response and compared the results with the raw data. As far as interpretation goes, here are examples of how one can get things wrong: The Berkeley group published a paper of the soft X-ray background that disagreed with ours. Why? It turned out they had **assumed** the galactic plane was completely opaque to soft X-ray and hence corrected for detector background that way. It turns out that the ISM emits in soft X-rays! Another example was the faux pas of the Calgary group. They didn’t properly shield their detector from the sounding rocket telemetry. Thus they got an enormous signal, which to our amusement some (ambulance chaser) theoreticians tried to explain! So back then as now, mistakes were made, but at least we all knew how our X-ray systems worked from soup (the detectors) to nuts (the data analysis code) where as toady “anybody” with a good idea but only a vague inkling of how detectors, mirrors and software work, can be an X-ray astronomer. On the one hand, this has made the field accessible to all, and on the other, errors in interpretation can be made as the X-ray telescope user can fall prey to running black box software. Furthermore with so much funding going into supporting observers, there is little left to make the necessary technology advances or keep the core expertise in place to even to stay even with

  9. The contribution of AGN to the X-ray background the effect of iron features

    CERN Document Server

    Gilli, R; Brunetti, G; Setti, G

    1999-01-01

    The contribution of the iron emission line, commonly detected in the X-ray spectra of Seyfert (Sey) galaxies, to the cosmic X-ray background (XRB) spectrum is evaluated in the framework of the XRB synthesis models based on AGN unification schemes. To derive the mean line properties, we have carried out a search in the literature covering a sample of about 70 AGN. When adopting line parameters in agreement with the observations, it turns out that the maximum contribution of the iron line to the XRB is less than 7% at a few keV. This is still below the present uncertainties in the XRB spectrum measurements.

  10. Ionization and heating by X-rays and cosmic rays*

    Directory of Open Access Journals (Sweden)

    Güdel Manuel

    2015-01-01

    Full Text Available High-energy radiation from the central T Tauri and protostars plays an important role in shaping protoplanetary disks and influences their evolution. Such radiation, in particular X-rays and extreme-ultraviolet (EUV radiation, is predominantly generated in unstable stellar magnetic fields (e.g., the stellar corona, but also in accretion hot spots. Even jets may produce X-ray emission. Cosmic rays, i.e., high-energy particles either from the interstellar space or from the star itself, are of crucial importance. Both highenergy photons and particles ionize disk gas and lead to heating. Ionization and heating subsequently drive chemical networks, and the products of these processes are accessible through observations of molecular line emission. Furthermore, ionization supports the magnetorotational instability and therefore drives disk accretion, while heating of the disk surface layers induces photoevaporative flows. Both processes are crucial for the dispersal of protoplanetary disks and therefore critical for the time scales of planet formation. This chapter introduces the basic physics of ionization and heating starting from a quantum mechanical viewpoint, then discusses relevant processes in astrophysical gases and their applications to protoplanetary disks, and finally summarizes some properties of the most important high-energy sources for protoplanetary disks.

  11. The LOFT (Large Observatory for X-ray Timing) background simulations

    CERN Document Server

    Campana, R; Del Monte, E; Brandt, S; Budtz-Jørgensen, C; Lund, N; Alvarez, J; Hernanz, M; Perinati, E

    2012-01-01

    The Large Observatory For X-ray Timing (LOFT) is an innovative medium-class mission selected for an assessment phase in the framework of the ESA M3 Cosmic Vision call. LOFT is intended to answer fundamental questions about the behaviour of matter in the very strong gravitational and magnetic fields around compact objects. With an effective area of ~10 m^2 LOFT will be able to measure very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and to optimize the instrument design. The two main contributions to the background are cosmic diffuse X-rays and high energy cosmic rays; also, albedo emission from the Earth is significant. These contributions to the background for both the Large Area Detector and the Wide Field Monitor are discussed, on the basis of extensive Geant-4 simulations of a simplified instrumental mass model.

  12. SAS 3 survey of the soft X-ray background

    Science.gov (United States)

    Marshall, F. J.; Clark, G. W.

    1984-01-01

    The results of a survey of the soft X-ray sky in the C band (0.10-0.28keV) are reported. The observations were carried out using two independent flow proportional counters on board the SAS 3 X-ray satellite which had a total angular resolution of 2.9 deg FWHM, and a total exposure of 2.2 x 10 to the 4th per sq cm s sr. It is found that C band counting rates were generally inversely correlated with the column density of the neutral hydrogen on all angular scales down to the lowest angular resolution of the detectors. In the region 90-180 deg l and 0-10 deg b, the relation between C-band rates and the column densities of neutral hydrogen was fitted with a residual rms deviation of less than 13 percent by a two-component numerical model of the X-ray background. For the apparent attenuation column density a value of 2.7 x 10 to the 20th per sq cm was obtained. On the basis of a computer simulation of the SAS 3 data, it is shown that the observed clumping of interstellar matter was consistent with the magnitude of spatial fluctuations in the C-band map. When the background rates were subtracted from the survey map, the subsequent map showed foreground emission and absorption features with improved sensitivity and clarity. A series of computer-generated maps incorporating the SAS 3 data is given in an appendix.

  13. Background Simulations of the Wide Field Imager of the ATHENA X-Ray Observatory

    CERN Document Server

    Hauf, Steffen; Pia, Maria Grazia; Hoffmann, Dieter H H; Lang, Philipp; Neff, Stephan; Stefanescu, Alexander; Strüder, Lothar

    2011-01-01

    The ATHENA X-ray Observatory-IXO is a planned multinational orbiting X-ray observatory with a focal length of 11.5m. ATHENA aims to perform pointed observations in an energy range from 0.1 keV to 15 keV with high sensitivity. For high spatial and timing resolution imaging and spectroscopic observations the 640x640 pixel^2 large DePFET-technology based Wide field Imager (WFI) focal plane detector, providing a field of view of 18 arcsec will be the main detector. Based on the actual mechanics, thermal and shielding design we present estimates for the WFI cosmic ray induced background obtained by the use of Monte-Carlo simulations and possible background reduction measures.

  14. Soft X-ray Absorbers Enabling Study of the Diffuse X-ray Background Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Absorbers for soft x-rays need to be made thinner and with larger area, to collect more photons, and with minimal number of support stems. However, the structure is...

  15. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    CERN Document Server

    Gavilan, L; Simionovici, A; Lemaire, J L; Sabri, T; Foy, E; Yagoubi, S; Henning, T; Salomon, D; Martinez-Criado, G

    2016-01-01

    Protoplanetary disks, interstellar clouds, and active galactic nuclei, contain X-ray dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Our goal is to study the effects of hard X-rays on cosmic dust analogs via in-situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments, and provide an upper limit on the effect of hard X-rays on dust grain structure. We prepared enstatite nanograins, analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy and high-resolution transmission electron microscopy before irradiation. Powder samples were prepared i...

  16. ISO investigates the nature of extremely-red hard X-ray sources responsible for the X-ray background

    CERN Document Server

    Franceschini, A; Césarsky, C J; Elbaz, D; Flores, H; Granato, G L; Franceschini, Alberto; Fadda, Dario; Cesarsky, Catherine; Elbaz, David; Flores, Hector; Granato, Gian Luigi

    2001-01-01

    We analyse very deep X-ray and mid-IR surveys in common areas of the Lockman Hole and the HDF North to study the sources of the X-ray background (XRB) and to test the standard obscured accretion paradigm. We detect with ISO a rich population of X-ray luminous sources with red optical colours, including a fraction identified with Extremely Red Objects (R-K > 5) and galaxies with SEDs typical of normal massive ellipticals or spirals at z ~ 1. The high 0.5-10 keV X-ray luminosities of these objects (1E43-1E45 erg/s) indicate that the ultimate energy source is gravitational accretion, while the X-ray to IR flux ratios and the X-ray spectral hardness show evidence of photoelectric absorption at low X-ray energies. An important hint on the physics comes from the mid-IR data at 6.7 and 15 um, well reproduced by model spectra of completely obscured quasars under standard assumptions and l.o.s. optical depths tau ~ 30-40. Other predictions of the standard XRB picture, like the distributions of intrinsic bolometric lum...

  17. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    Science.gov (United States)

    Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

    2016-03-01

    Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization

  18. X-Ray Probes of Cosmic Star Formation History

    Science.gov (United States)

    Ghosh, Pranab; White, Nicholas E.

    2001-01-01

    We discuss the imprints left by a cosmological evolution of the star formation rate (SFR) on the evolution of X-ray luminosities Lx of normal galaxies, using the scheme earlier proposed by us, wherein the evolution of LX of a galaxy is driven by the evolution of its X-ray binary population. As indicated in our earlier work, the profile of Lx with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. We report here the first calculation of the expected evolution of X-ray luminosities of galaxies, updating our work by using a suite of more recently developed SFR profiles that span the currently plausible range. The first Chandra deep imaging results on Lx evolution are beginning to probe the SFR profile of bright spiral galaxies; the early results are consistent with predictions based on current SFR models. Using these new SFR profiles, the resolution of the "birthrate problem" of low-mass X-ray binaries and recycled, millisecond pulsars in terms of an evolving global SFR is more complete. We discuss the possible impact of the variations in the SFR profile of individual galaxies and galaxy types.

  19. K-alpha X-rays from cosmic ray oxygen. [Detection and calculation of equilibrium charge fractions

    Science.gov (United States)

    Pravdo, S. H.; Boldt, E. A.

    1975-01-01

    Equilibrium charge fractions are calculated for subrelativistic cosmic ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relating these results to the diffuse X-ray background measured at the appropriate energy level suggests an observable line feature. If the flux of low energy cosmic ray oxygen is sufficiently large, K-alpha X-ray line emission from these nuclei will comprise a significant fraction of the total diffuse flux at approximately 0.6 keV. A satellite borne detector with a resolution greater than 30 percent could observe this feature if the subrelativistic interstellar cosmic ray oxygen spectrum is as large as certain theoretical estimates expressed in the text.

  20. Spectacular X-ray Jet Points Toward Cosmic Energy Booster

    Science.gov (United States)

    2000-06-01

    NASA's Chandra X-ray Observatory has revealed a spectacular luminous spike of X rays that emanates from the vicinity of a giant black hole in the center of the radio galaxy Pictor A. The spike, or jet, is due to a beam of particles that streaks across hundreds of thousands of light years of intergalactic space toward a brilliant X-ray hot spot that marks its end point. Pictor A Image Press Image and Caption The hot spot is at least 800 thousand light years (8 times the diameter of our Milky Way galaxy) away from where the jet originates. It is thought to represent the advancing head of the jet, which brightens conspicuously where it plows into the tenuous gas of intergalactic space. The jet, powered by the giant black hole, originates from a region of space no bigger than the solar system. "Both the brightness and the spectrum of the X rays are very different from what theory predicts," Professor Andrew Wilson reported today at the 196th national meeting of the American Astronomical Society in Rochester, New York. Wilson, of the University of Maryland, College Park, along with Dr. Patrick Shopbell and Dr. Andrew Young, also of the University of Maryland, are submitting an article on this research to the Astrophysical Journal. "The Chandra observations are telling us that something out there is producing many more high-energy particles than we expected," said Wilson. One possible explanation for the X rays is that shock waves along the side and head of the X-ray jet are accelerating electrons and possibly protons to speeds close to that of light. In the process the electrons are boosted to energies as high as 100 million times their own rest mass energy. These electrons lose their energy rapidly as they produce X rays, so this could be the first direct evidence of this process so far outside a galaxy. The hot spot has been seen with optical and radio telescopes. Radio telescopes have also observed a faint jet. Jets are thought to be produced by the extreme

  1. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  2. The role of the background in past and future X-ray missions

    Science.gov (United States)

    Molendi, Silvano

    2017-09-01

    Background has played an important role in X-ray missions, limiting the exploitation of science data in several and sometimes unexpected ways. In this presentation I review past X-ray missions focusing on some important lessons we can learn from them. I then go on discussing prospects for overcoming background related limitations in future ones.

  3. In-orbit background of X-ray microcalorimeters and its effects on observations

    Science.gov (United States)

    Lotti, S.; Cea, D.; Macculi, C.; Mineo, T.; Natalucci, L.; Perinati, E.; Piro, L.; Federici, M.; Martino, B.

    2014-09-01

    Context. Observations in the X-ray energy band are often limited by the background because of the low fluxes of typical sources. The background can easily be higher than the signal itself, and thus any mission with the scientific goal of observing faint and/or extended sources in the X-ray band must deal with the background problem. ESA has recently selected "the hot and energetic universe" as science theme for the second large-class mission in the Cosmic Vision science program, to be pursued with an advanced X-ray observatory to be launched in 2028, and at present ATHENA is the proposal that is most likely to be selected for this slot. The mission is aimed to place an X-ray telescope in the L2 orbit equipped with an X-ray Integral Field Unit (X-IFU) based on high spectral resolution transition-edge microcalorimeters, and has among its goals the detection and characterization of high-redshift active galactic nuclei (AGNs), cluster of galaxies and their outskirts, which is why great care must be taken to reduce the background impact on the detection/characterization of these sources. Aims: The background is composed of a diffuse component and an internal particle component for any satellite operating in the X-ray band. We take as reference the X-ray IFU instrument that will be placed onboard the ATHENA mission to analyze both these components and their variability for different orbits, observational conditions and/or design choices. We also show how different background levels affect the instrumental performance, and the scientific results obtainable with the instrument in the best configuration. The X-IFUis a cryogenic X-ray spectrometer, based on a large array of 3840 transition-edge sensors (TES) of 250 μm side, with a spectral energy resolution of 2.5 eVin the 0.2-10 keVenergy band, over a field of view of 5 × 5 arcmin2, high count rate capability and a 5 arcsec angular resolution. Methods: There are no experimental data about the background experienced by

  4. Background simulations for the wide field imager aboard the ATHENA X-ray Observatory

    Science.gov (United States)

    Hauf, Steffen; Kuster, Markus; Hoffmann, Dieter H. H.; Lang, Philipp-Michael; Neff, Stephan; Pia, Maria Grazia; Strüder, Lothar

    2012-09-01

    The ATHENA X-ray observatory was a European Space Agency project for a L-class mission. ATHENA was to be based upon a simplified IXO design with the number of instruments and the focal length of the Wolter optics being reduced. One of the two instruments, the Wide Field Imager (WFI) was to be a DePFET based focal plane pixel detector, allowing for high time and spatial resolution spectroscopy in the energy-range between 0.1 and 15 keV. In order to fulfill the mission goals a high sensitivity is essential, especially to study faint and extended sources. Thus a detailed understanding of the detector background induced by cosmic ray particles is crucial. During the mission design generally extensive Monte-Carlo simulations are used to estimate the detector background in order to optimize shielding components and software rejection algorithms. The Geant4 toolkit1,2 is frequently the tool of choice for this purpose. Alongside validation of the simulation environment with XMM-Newton EPIC-pn and Space Shuttle STS-53 data we present estimates for the ATHENA WFI cosmic ray induced background including long-term activation, which demonstrate that DEPFET-technology based detectors are able to achieve the required sensitivity.

  5. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    Science.gov (United States)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  6. Cosmic microwave background theory.

    Science.gov (United States)

    Bond, J R

    1998-01-06

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in -space are consistent with a DeltaT flat in frequency and broadly follow inflation-based expectations. That the levels are approximately (10(-5))2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Lambda cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 +/- 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 +/- 0.08 for DMR plus the SK95 experiment; 1.00 +/- 0.04 for DMR plus all smaller angle experiments; 1.00 +/- 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Lambda and moderate constraints on Omegatot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant.

  7. X-Ray Background at High Redshifts from Pop III Remnants: Results from Pop III Star Formation Rates in the Renaissance Simulations

    Science.gov (United States)

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

    2016-11-01

    Due to their long mean free paths, X-rays are expected to have global impacts on the properties of the intergalactic medium (IGM) by their large-scale heating and ionizing processes. At high redshifts, X-rays from Population (Pop) III binaries might have important effects on cosmic reionization and the Lyα forest. As a continuation of our previous work on Pop III binary X-rays, we use the Pop III distribution and evolution from the Renaissance Simulations, a suite of self-consistent cosmological radiation hydrodynamics simulations of the formation of the first galaxies, to calculate the X-ray luminosity density and background over the redshift range 20≥slant z≥slant 7.6. As we find that Pop III star formation continues at a low, nearly constant rate to the end of reionization, X-rays are being continuously produced at significant rates compared to other possible X-ray sources, such as AGNs and normal X-ray binaries during the same period of time. We estimate that Pop III binaries produce approximately 6 eV of energy in the X-rays per hydrogen atom. We calculate the X-ray background for different monochromatic photon energies. KeV X-rays redshift and accumulate to produce a strong X-ray background spectrum extending to roughly 500 eV. The X-ray background is strong enough to heat the IGM to ˜1000 K and to ionize a few percent of the neutral hydrogen. These effects are important for an understanding of the neutral hydrogen hyperfine transition 21 cm line signatures, the Lyα forest, and the Thomson optical depth to the CMB.

  8. Cosmic axion background propagation in galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Day, Francesca V., E-mail: francesca.day@physics.ox.ac.uk

    2016-02-10

    Many extensions of the Standard Model include axions or axion-like particles (ALPs). Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB) analogous to the CMB, whose existence is suggested by string models of inflation. ALP–photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP–photon conversion in the Milky Way would be unobservably small. The ALP–photon conversion probability in galaxy clusters is 3 orders of magnitude higher than that in the Milky Way. Furthermore, the morphology of the unresolved cosmic X-ray background is incompatible with a significant component from ALP–photon conversion. We also consider ALP–photon conversion in starburst galaxies, which host much higher magnetic fields. By considering the clumpy structure of the galactic plasma, we find that conversion probabilities comparable to those in clusters may be possible in starburst galaxies.

  9. The Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Jones Aled

    1998-01-01

    Full Text Available We present a brief review of current theory and observations of the cosmic microwave background (CMB. New predictions for cosmological defect theories and an overview of the inflationary theory are discussed. Recent results from various observations of the anisotropies of the microwave background are described and a summary of the proposed experiments is presented. A new analysis technique based on Bayesian statistics that can be used to reconstruct the underlying sky fluctuations is summarised. Current CMB data is used to set some preliminary constraints on the values of fundamental cosmological parameters $Omega$ and $H_circ$ using the maximum likelihood technique. In addition, secondary anisotropies due to the Sunyaev-Zel'dovich effect are described.

  10. A Joint Model Of X-ray And Infrared Backgrounds. II. Compton-Thick AGN Abundance

    CERN Document Server

    Shi, Yong; Armus, Lee

    2013-01-01

    We estimate the abundance of Compton-thick (CT) active galactic nuclei (AGN) based on our joint model of X-ray and infrared backgrounds. At L_{rest 2-10 keV} > 10^42 erg/s, the CT AGN density predicted by our model is a few 10^-4 Mpc^-3 from z=0 up to z=3. CT AGN with higher luminosity cuts (> 10^43, 10^44 & 10^45 erg/s) peak at higher z and show a rapid increase in the number density from z=0 to z~2-3. The CT to all AGN ratio appears to be low (2-5%) at f_{2-10keV} > 10^-15 erg/s/cm^2 but rises rapidly toward fainter flux levels. The CT AGN account for ~ 38% of the total accreted SMBH mass and contribute ~ 25% of the cosmic X-ray background spectrum at 20 keV. Our model predicts that the majority (90%) of luminous and bright CT AGN (L_{rest 2-10 keV} > 10^44 erg/s or f_{2-10keV} > 10^-15 erg/s/cm^2) have detectable hot dust 5-10 um emission which we associate with a dusty torus. The fraction drops for fainter objects, to around 30% at L_{rest 2-10 keV} > 10^42 erg/s or f_{2-10keV} > 10^-17 erg/s/cm^2. Ou...

  11. The X-ray log N-log S relation. [background radiation in extragalactic media

    Science.gov (United States)

    Boldt, Elihu

    1989-01-01

    Results from various surveys are reviewed as regards X-ray source counts at high galactic latitudes and the luminosity functions determined for extragalactic sources. Constraints on the associated log N-log S relation provided by the extragalactic X-ray background are emphasized in terms of its spatial fluctuations and spectrum as well as absolute flux level. The large number of sources required for this background suggests that there is not a sharp boundary in the redshift distribution of visible matter.

  12. X-ray stacking of Lyman break galaxies in the 4\\,Ms CDF-S - X-ray luminosities and star formation rates across cosmic time

    CERN Document Server

    Zinn, Peter-Christian; Seymour, Nicholas; Bomans, Dominik J

    2012-01-01

    Lyman Break Galaxies (LBGs) are widely thought to be prototypical young galaxies in the early universe, particularly representative of those undergoing massive events of star formation. Therefore, LBGs should produce significant amounts of X-ray emission. We aim to trace the X-ray luminosity of Lyman Break Galaxies across cosmic time and from that derive constraints on their star formation history. We utilize the newly released 4 Ms mosaic obtained with the Chandra X-ray Observatory, the deepest X-ray image to date, alongside with the superb spectroscopic data sets available in the CDF-S survey region to construct large but nearly uncontaminated samples of LBGs across a wide range of redshift (0.5 < z < 4.5) which can be used as input samples for stacking experiments. This approach allows us to trace the X-ray emission of Lyman Break Galaxies to even lower, previously unreachable, flux density limits (~10^-18 mW m^-2) and therefore to larger redshifts. We reliably detect soft-band X-ray emission from al...

  13. Evidence for the Missing Baryons in the Angular Correlation of the Diffuse X-ray Background

    CERN Document Server

    Galeazzi, M; Ursino, E

    2008-01-01

    The amount of detected baryons in the local Universe is at least a factor of two smaller than measured at high redshift. It is believed that a significant fraction of the baryons in the current Universe is "hiding" in a hot filamentary structure filling the intergalactic space, the Warm-Hot Intergalactic Medium ($WHIM$). We found evidence of the missing baryons in the $WHIM$ by detecting their signature on the angular correlation of diffuse X-ray emission with the XMM-Newton satellite. Our result indicates that $(12\\pm 5)$% of the total diffuse X-ray emission in the energy range 0.4-0.6 keV is due to intergalactic filaments. The statistical significance of our detection is several sigmas ($\\chi ^2>136$ N=19). The error bar in the X-ray flux is dominated, instead, by cosmic variation and model uncertainties.

  14. Effect of cosmic ray/X-ray ionization on supermassive black hole formation

    CERN Document Server

    Inayoshi, Kohei

    2011-01-01

    We study effects of external ionization by cosmic rays (CRs) and X-rays on the thermal evolution of primordial clouds under strong far-ultraviolet (FUV) radiation. A strong FUV radiation dissociates H2 and quenches its cooling. Even in such an environment, a massive cloud with Tvir>10^4 K can contract isothermally at 8000 K by Lyman alpha cooling. This cloud collapses monolithically without fragmentation, and a supermassive star (>10^5 Msun) is believed to form at the center, which eventually evolves to a supermassive black hole (SMBH). However, candidates of FUV sources, including star-forming galaxies, are probably sources of strong CRs and X-rays, as well. We find that the external ionization promotes H2 production and elevates the threshold FUV intensity Jcr needed for the SMBH formation for CR energy density U_CR>10^-14 erg/cm^3 or X-ray intensity J_X>10^-24 erg/s/cm^2/sr/Hz at 1 keV. The critical FUV flux increases in proportion to U_CR^{1/2} (J_X^{1/2}) in the high CR (X-ray, respectively) limit. With ...

  15. Simulating the Impact of X-ray Heating during the Cosmic Dawn

    CERN Document Server

    Ross, Hannah E; Iliev, Ilian T; Mellema, Garrelt

    2016-01-01

    Upcoming observations of the 21-cm signal from the Epoch of Reionization will soon provide us with the first direct detection of this era. This signal is influenced by many astrophysical effects, including long range X-ray heating of the intergalactic gas. During the preceding Cosmic Dawn era the impact of this heating on the 21-cm signal is particularly prominent, especially before spin temperature saturation. We present the largest-volume (244~$h^{-1}$Mpc=349\\,Mpc comoving) full numerical radiative transfer simulations to date of this epoch, including the effects of helium and multi-frequency heating, both with and without X-ray sources. We show that X-ray sources can contribute significantly to early heating of the neutral intergalactic medium and, hence, to the corresponding 21-cm signal. The inclusion of hard, energetic radiation yields an earlier, extended transition from absorption to emission compared to the stellar-only case. The presence of X-ray sources decreases the absolute value of the mean 21-c...

  16. Cosmic Microwave Background Mapping

    Science.gov (United States)

    Verkhodanov, O. V.; Doroshkevich, A. G.

    2012-03-01

    The last decade of research in cosmology was connected with the ambitious experiments including space and ground base observations. Among the most impressive results of these investigations are the measurements of the cosmic microwave background (CMB) radiation like WMAP* and Planck. Exactly from the CMB studies, we have started the epoch of the precision cosmology when generally the values of cosmological parameters have been known and present research is devoted to improvement of the precision. These achievements are connected with both the creation of the new facilities in millimeter and submillimeter astronomy (e.g., satellites, receivers, antennas, computers) and development of the methods for the CMB data analysis. Actually, the process of data analysis contains several technical stages including 1. Registration of time-ordered data (TOD) 2. Pixelization of the CMB data - map preparation 3. Component separation 4. Map statistics analysis 5. Map - spherical harmonics transformation 6. C(l)-spectrum calculation and spectrum statistics analysis 7. Cosmological parameters estimation Starting from the cosmic background explorer (COBE) experiment using the so-called Quadrilateralized Sky Cube Projection (see [1-3]), the problem of the whole sky CMB pixelization has attracted great interest and many such schemes were developed. Let us note however that accurate pixelization of the CMB data on the sphere is very important but not the final step of analysis. Usually, the next step implies the determination of the coefficients of the spherical harmonic decomposition of the CMB signal for both anisotropy and polarization. This means that some of the pixelization schemes provide a very accurate map but are inconvenient for further decomposition. This also means that the choice of suitable pixelization schemes depends upon the general goals of the investigation. In this review, we consider several of the most popular sky map pixelization schemes and link them with the

  17. Excess astrophysical photons from a 0.1-1 keV cosmic axion background.

    Science.gov (United States)

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

    Primordial decays of string theory moduli at z~10(12) naturally generate a dark radiation cosmic axion background with 0.1-1 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario.

  18. Detecting X-ray Synchrotron Emission in Supernova Remnants Implications for Abundances and Cosmic Rays

    CERN Document Server

    Dyer, K K; Borkowski, K J; Petre, R; Dyer, Kristy K.; Reynolds, Stephen P; Borkowski, Kazik J.; Petre, Robert

    2000-01-01

    The 10^51 ergs released in a supernova have far reaching consequences in the galaxy, determining elemental abundances, accelerating cosmic rays, and affecting the makeup of the interstellar medium. Recently the spectra of several supernova remnants have been found to be dominated by nonthermal emission. Separating the thermal and nonthermal components is important not only for the understanding of cosmic-ray acceleration and shock microphysics properties but for accurate assessment of the temperatures and line strengths. New models designed to model spatially resolved synchrotron X-rays from type Ia supernovae can contribute to the understanding of both the thermal physics (dynamics, abundances) and nonthermal physics (shock acceleration, magnetic-field amplification) of supernova remnants. I will describe model fits to SN 1006, emphasizing the physical constraints that can be placed on SNRs, abundances, and the cosmic-ray acceleration process.

  19. Measuring x-ray polarization in the presence of systematic effects: Known background

    CERN Document Server

    Elsner, Ronald F; Weisskopf, Martin C

    2012-01-01

    The prospects for accomplishing x-ray polarization measurements of astronomical sources have grown in recent years, after a hiatus of more than 37 years. Unfortunately, accompanying this long hiatus has been some confusion over the statistical uncertainties associated with x-ray polarization measurements of these sources. We have initiated a program to perform the detailed calculations that will offer insights into the uncertainties associated with x-ray polarization measurements. Here we describe a mathematical formalism for determining the 1- and 2-parameter errors in the magnitude and position angle of x-ray (linear) polarization in the presence of a (polarized or unpolarized) background. We further review relevant statistics-including clearly distinguishing between the Minimum Detectable Polarization (MDP) and the accuracy of a polarization measurement.

  20. The History of Cosmic Baryons X-ray Emission vs. Star Formation Rate

    CERN Document Server

    Menci, N

    1999-01-01

    We relate the star formation from cold baryons in virialized structures to the X-ray properties of the associated diffuse, hot baryonic component. Our computations use the standard ``semi-analytic'' models to describe i) the evolution of dark matter halos through merging after the hierarchical clustering, ii) the star formation governed by radiative cooling and by supernova feedback, iii) the hydro- and thermodynamics of the hot gas, rendered with our Punctuated Equilibria model. So we relate the X-ray observables concerning the intra-cluster medium to the thermal energy of the gas pre-heated and expelled by supernovae following star formation, and then accreted during the subsequent merging events. We show that at fluxes fainter than $F_X\\approx 10^{-15}$ erg/cm$^2 $ s (well within the reach of next generation X-ray observatories) the X-ray counts of extended extragalactic sources (as well as the faint end of the luminosity function, the contribution to the soft X-ray background, and the $L_X-T$ correlation ...

  1. Preliminary assessment of the ATHENA/WFI non-X-ray background

    Science.gov (United States)

    Perinati, Emanuele; Barbera, Marco; Diebold, Sebastian; Guzman, Alejandro; Santangelo, Andrea; Tenzer, Chris

    2017-06-01

    We present a preliminary assessment of the non-X-ray background for the WFI on board ATHENA conducted at IAAT in the context of the collaborative background and radiation damage working group activities. Our main result is that in the baseline configuration originally assumed for the camera the requirement on the level of non-X-ray background could not be met. In light of the results of Geant4 simulations we propose and discuss a possible optimization of the camera design and pinpoint some open issues to be addressed in the next phase of investigation. One of these concerns the possible contribution to the non-X-ray background from soft protons and ions funneled to the focal plane through the optics. This is not quantified at this stage, here we just briefly report on our ongoing activities aimed at validating the mechanisms of proton scattering at grazing incidence.

  2. Using the Maximum X-ray Flux Ratio and X-ray Background to Predict Solar Flare Class

    CERN Document Server

    Winter, Lisa M

    2015-01-01

    We present the discovery of a relationship between the maximum ratio of the flare flux (namely, 0.5-4 Ang to the 1-8 Ang flux) and non-flare background (namely, the 1-8 Ang background flux), which clearly separates flares into classes by peak flux level. We established this relationship based on an analysis of the Geostationary Operational Environmental Satellites (GOES) X-ray observations of ~ 50,000 X, M, C, and B flares derived from the NOAA/SWPC flares catalog. Employing a combination of machine learning techniques (K-nearest neighbors and nearest-centroid algorithms) we show a separation of the observed parameters for the different peak flaring energies. This analysis is validated by successfully predicting the flare classes for 100% of the X-class flares, 76% of the M-class flares, 80% of the C-class flares and 81% of the B-class flares for solar cycle 24, based on the training of the parametric extracts for solar flares in cycles 22-23.

  3. Cosmic axion background propagation in galaxies

    Directory of Open Access Journals (Sweden)

    Francesca V. Day

    2016-02-01

    Full Text Available Many extensions of the Standard Model include axions or axion-like particles (ALPs. Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB analogous to the CMB, whose existence is suggested by string models of inflation. ALP–photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP–photon conversion in the Milky Way would be unobservably small. The ALP–photon conversion probability in galaxy clusters is 3 orders of magnitude higher than that in the Milky Way. Furthermore, the morphology of the unresolved cosmic X-ray background is incompatible with a significant component from ALP–photon conversion. We also consider ALP–photon conversion in starburst galaxies, which host much higher magnetic fields. By considering the clumpy structure of the galactic plasma, we find that conversion probabilities comparable to those in clusters may be possible in starburst galaxies.

  4. The 2-10 keV X-Ray Background Dipole and Its Cosmological Implications

    Science.gov (United States)

    Scharf, C. A.; Jahoda, K.; Treyer, M.; Lahav, O.; Boldt, E.; Piran, T.

    2000-11-01

    The hard X-ray (>2 keV) emission of the local and distant universe as observed with the HEAO 1 A-2 experiment is reconsidered in the context of large-scale cosmic structure. Using all-sky X-ray samples of active galactic nuclei (AGNs) and galaxy clusters, we remove the dominant local X-ray flux from within a redshift of ~0.02. We evaluate the dipolar and higher order harmonic structure in four X-ray colors. The estimated dipole anisotropy of the unresolved flux appears to be consistent with a combination of the Compton-Getting effect due to the Local Group motion (dipole amplitude Δ=0.0042) and remaining large-scale structure (0.00232 keV Galactic X-ray emission. Comparison of the soft and hard color maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data qualitatively suggests that at least a third of the faint, unresolved ~18° scale structure in the HEAO 1 A-2 data may be Galactic in origin. However, the effect on measured flux dipoles is small (frame can constrain the amplitude of bulk motions of the universe. From observed bulk motions over a local ~50 h-1 Mpc radius volume, we determine 0.14<~Ω0.60/bX(0)<~0.59, where Ω0 is the universal density parameter and bX(0) is the present-epoch bias parameter, defined as the ratio of fluctuations in the X-ray source density and the mass density.

  5. Measuring the X-ray Background in the Reionization Era with First Generation 21 cm Experiments

    OpenAIRE

    Christian, Pierre; Loeb, Abraham

    2013-01-01

    The X-ray background during the epoch of reionization is currently poorly constrained. We demonstrate that it is possible to use first generation 21 cm experiments to calibrate it. Using the semi-numerical simulation, 21cmFAST, we calculate the dependence of the 21 cm power spectrum on the X-ray background flux. Comparing the signal to the sensitivity of the Murchison Widefield Array (MWA) we find that in the redshift interval z=8-14 the 21 cm signal is detectable based on the upper limit set...

  6. X-ray Background at High Redshifts from Pop III Remnants: Results from Pop III star formation rates in the Renaissance Simulations

    CERN Document Server

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

    2016-01-01

    Due to their long mean free paths, X-rays are expected to have many significant impacts globally on the properties of the intergalactic medium (IGM) by their heating and ionizing processes on large scales. At high redshifts, X-rays from Population (Pop) III binaries might have important effects on cosmic reionization and the Lyman alpha forest. As a continuation of our previous work on Pop III binary X-rays (Xu et al. 2014), we use the Pop III distribution and evolution from the Renaissance Simulations, a suite of self-consistent cosmological radiation hydrodynamics simulations of the formation of the first galaxies, to calculate the X-ray luminosity density and background over the redshift range 20 > z > 7.6. As we find that Pop III star formation continues at a low, nearly constant rate to the end of reionization, X-rays are being continuously produced at significant rates compared to other possible X-ray sources, such as AGNs and normal X-ray binaries during the same period of time. We estimate that Pop II...

  7. Observed Limits on Charge Exchange Contributions to the Diffuse X-Ray Background

    Science.gov (United States)

    Crowder, S. G.; Barger, K. A.; Brandl, D. E.; Eckart, M. E.; Galeazzi, M.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Pfendner, C. G.; Porter, F. S.; hide

    2012-01-01

    We present a high-resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for an approximately 1 sr region of the sky centered at l = 90 degrees b = +60 degrees using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum s observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568 (sup +2 (sub -3) eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV and for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex. The dominance of thermal emission is consistent with much of the high-latitude O VII emission originating in 2-3 x 10(exp 6) K gas in the Galactic halo. On the other hand, the observed ratio of C VI Lygamma to Lyalpha is 0.3 plus or minus 0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 10(sup 6) K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only greater than 32% thermal emission for O VII and greater than 20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument.

  8. The non-thermal X-ray emission of SN 1006 and the implications for cosmic rays

    Science.gov (United States)

    Allen, G. E.; Petre, R.; Gotthelf, E. V.

    2001-05-01

    We present the results of a spectral analysis of RXTE, ASCA, and ROSAT data of SN 1006. These data were fit with several sets of thermal and non-thermal X-ray emission models to characterize the global spectral properties of the remnant. The present work represents the first attempt to model both the thermal and non-thermal X-ray emission over the entire X-ray energy band from 0.12-17 keV. The non-thermal X-ray spectrum is described by a broken power-law with low- and high-energy photon indices of 2.1 and 3.0, respectively. Since this spectrum steepens with increasing energy, our results support the claims that the emission is produced by synchrotron radiation from 100 TeV electrons. Using the radio and X-ray data, we estimate the parameters of the cosmic-ray electron, proton, and helium spectra. The results suggest that the ratio of the number densities of protons and electrons is 150 at 1 GeV and that the total energy in cosmic rays is 1050 erg. These results and the spectral index of the electrons at 1 GeV (Γe=2.14+/-0.12) are consistent with the hypothesis that Galactic cosmic rays are predominantly accelerated in the shocks of supernova remnants. However, SN 1006 may or may not accelerate cosmic-ray protons to energies approaching the ``knee'' in the cosmic-ray spectrum. .

  9. What's wrong with AGN models for the X-ray background?

    CERN Document Server

    Comastri, A

    2000-01-01

    The origin of the hard X-ray background (XRB) as a superposition of unabsorbed and absorbed Active Galactic Nuclei is now widely accepted as the standard model. The identification of faint X-ray sources in ROSAT, ASCA, and BeppoSAX medium-deep surveys and their average spectral properties are in broad agreement with the model predictions. However, AGN models, at least in their simplified version, seem to be at odds with some of the most recent findings calling for substantial revisions. I will review the recent XRB "best fit" models and discuss how the foreseen XMM and Chandra surveys will be able to constrain the allowed parameter space.

  10. Piecing Together the X-ray Background: Bolometric Corrections for Active Galactic Nuclei

    CERN Document Server

    Vasudevan, R V

    2007-01-01

    (Abridged) The X-ray background can be used to constrain the accretion history of Supermassive Black Holes (SMBHs) in Active Galactic Nuclei (AGN). A knowledge of the hard X-ray bolometric correction, \\kappa_{2-10keV} is a vital input into these studies. Variations in the disk emission in the UV have not previously been taken into account in calculating \\kappa_{2-10keV}; we show that such variations are important by constructing optical--to--X-ray SEDs for 54 AGN. In particular, we use FUSE UV and X-ray data from the literature to constrain the disk emission as well as possible. Previous work has suggested a dependence of \\kappa_{2-10keV} on AGN luminosity, but we find significant spread in \\kappa_{2-10keV} with no simple dependence on luminosity. Populations such as Narrow-Line Seyfert 1 nuclei (NLS1s), Radio Loud and X-ray Weak AGN may have values of \\kappa_{2-10keV} differing systematically from the rest of the AGN population. Other sources of uncertainty include intrinsic extinction in the optical--UV, X-...

  11. The Antennae Ultraluminous X-Ray Source, X-37, Is A Background Quasar

    CERN Document Server

    Clark, D M; Eikenberry, S S; Brandl, B R; Wilson, J C; Carson, J C; Henderson, C P; Hayward, T L; Barry, J; Ptak, A F; Colbert, E J M

    2005-01-01

    In this paper we report that a bright, X-ray source in the Antennae galaxies (NGC 4038/9), previously identified as an ultra-luminous X-ray source, is in fact a background quasar. We identify an isolated infrared and optical counterpart within 0.3+/-0.5 arcseconds the X-ray source X-37. After acquiring an optical spectrum of its counterpart, we use the narrow [OIII] and broad H_alpha emission lines to identify X-37 as a quasar at a redshift of z=0.26. Through a U, V, and K_s photometric analysis, we demonstrate that most of the observable light along this line of sight is from the quasar. We discuss the implications of this discovery and the importance of acquiring spectra for optical and IR counterparts to ULXs.

  12. Cross-correlations between 21 cm,X-ray and infrared backgrounds

    Institute of Scientific and Technical Information of China (English)

    Huan-Yuan Shan; Bo Qin

    2009-01-01

    The history of the cosmological reionization is still unclear. Two ionizing sources, stars and QSOs, are believed to play important roles during this epoch. Besides the 21 cm signals, the infrared emission from Pop Ⅲ stars and X-ray photons from QSOs can be powerful probes of the reionization. Here we present a cross-correlation study of the 21 cm, infrared and X-ray backgrounds. The advantage of doing such cross-correlations is that we could highlight the correlated signals and eliminate irrelevant fore-grounds. We develop a shell model to describe the 21 cm signals and find that PopⅢ stars can provide higher 21 cm signals than QSOs. Using the ROSAT data for X-ray and AKARI data for infrared, we predict various cross power spectra analytically and dis-cuss prospects for detecting these cross-correlation signals in future low frequency radio surveys. We find that, although these cross-correlational signals have distinct features, so far, they have been difficult to detect due to the high noise of the soft X-ray and infrared backgrounds given by ROSAT and AKARI.

  13. Low-Mass X-Ray Binaries, Millisecond Radio Pulsars, and the Cosmic Star Formation Rate

    CERN Document Server

    White, N E; White, Nicholas E.; Ghosh, Pranab

    1998-01-01

    We report on the implications of the peak in the cosmic star-formation rate (SFR) at redshift z ~ 1.5 for the resulting population of low-mass X-ray binaries(LMXB) and for that of their descendants, the millisecond radio pulsars (MRP). Since the evolutionary timescales of LMXBs, their progenitors, and their descendants are thought be significant fractions of the time-interval between the SFR peak and the present epoch, there is a lag in the turn-on of the LMXB population, with the peak activity occurring at z ~ 0.5 - 1.0. The peak in the MRP population is delayed further, occurring at z < 0.5. We show that the discrepancy between the birthrate of LMXBs and MRPs, found under the assumption of a stead-state SFR, can be resolved for the population as a whole when the effects of a time-variable SFR are included. A discrepancy may persist for LMXBs with short orbital periods, although a detailed population synthesis will be required to confirm this. Further, since the integrated X-ray luminosity distribution of...

  14. Hot Gas in the Diffuse Interstellar Medium: The Soft X-ray Background

    Science.gov (United States)

    Sanders, Wilton

    1996-05-01

    The immediate solar neighborhood, the nearest 100 pc or so, is filled with hot low-density gas that has a substantial thermal pressure and is a dominant factor in the energy budget of the local interstellar medium. This gas produces substantial soft thermal soft x-ray emission below 1/4 keV, but is difficult to observe outside the soft x-ray band. Sounding rocket and satellite all-sky surveys in several broad x-ray energy bands provided the general picture of this million-degree gas surrounding the solar system, extending perhaps as far as 100 pc in the galactic plane and roughly twice that far out of the plane, and showing no signs of being absorbed by intervening neutral gas. ROSAT observations of "shadows" in the diffuse x-ray background have subsequently determined the spatial locations of this hot gas along a few lines of sight: closer than 65 pc in some low galactic latitude directions, farther than several hundred pc in some high galactic latitude directions. Other large regions of hot gas are seen nearby, within a few hundred parsecs, but the galactic filling factor of the hot gas is unknown. DXS obsrvations of the spectra of the diffuse soft x-ray background confirm that the emission in the plane is thermal, but the spectrum of the hot gas is not fit by standard thermal equilibrium models. The temperature distribution, emission measure, ionization distributions, and metallicity of the hot gas are unknown. This talk emphasizes a few of the things that are clear about the hot ISM, and discusses a few of the most puzzling problems in our understanding of the nature of the diffuse hot gas. New instruments with hig spectral resolution will make it possible to address some of these problems.

  15. Cosmic Tachyon Background Radiation

    CERN Document Server

    Tomaschitz, R

    1999-01-01

    The equilibrium statistical mechanics of a background radiation of superluminal particles is investigated, based on a vectorial wave equation for tachyons of the Proca type. The partition function, the spectral energy density, and the various thermodynamic variables of an ideal Bose gas of tachyons in an open Robertson-Walker cosmology are derived. The negative mass square in the wave equation changes the frequency scaling in the Rayleigh-Jeans law, and there are also significant changes in the low temperature regime as compared to the microwave background, in particular in the caloric and thermal equations of state.

  16. Cosmic axion background propagation in galaxies

    CERN Document Server

    Day, Francesca V

    2015-01-01

    Many extensions of the Standard Model include axions or axion-like particles (ALPs). Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB) analogous to the CMB, whose existence is suggested by string models of inflation. ALP-photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP-photon conversion in the Milky Way would be unobservably small. The ALP-photon conversion prob...

  17. Fingerprints of the first black holes? Crosscorrelationg the Near-Infrared and X-ray background in COSMOS

    Science.gov (United States)

    Hasinger, Guenther

    Unresolved cosmic backgrounds carry information about the populations of stars and black holes not accessible by any other current observational technique. Studies using both Spitzer and AKARI have revealed large-scale fluctuations in the Cosmic Infrared Background (CIB) after subtracting resolved sources to faint levels. The signal, which is stronger than all foreground contributions, has been attributed to the earliest light in the universe. Other teams, by using Spitzer and CIBER, suggested that this signal could originate from stars tidally stripped from their parent galaxies at low redshift as a result of mergers. Only sensitive multi-wavelength observations can distinguish between these radically different interpretations. Recently our team discovered an intriguing cross-correlation signal between the unresolved CIB and X-ray background (CXB) suggesting significant black hole populations among the CIB sources (C13). The analysis used data from Spitzer and Chandra in an overlapping 8'x45' region of the All-Wavelength Extended Groth strip International Survey (AEGIS), probing the clustering of the underlying sources to angular scales 20', but the experiment is limited by the size and the elongated configuration of the field. Here we propose to use the much more extended multiwavelength observations in the COSMOS field to obtain new constraints on this important debate. Spitzer has recently completed the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH), which observed the full 2 square degree COSMOS field to about half the depth of the AEGIS field, but a 20 times larger sky area. SPLASH, focusing on the COSMOS field with excellent multi-wavelength coverage from space and ground-based observatories, is ideally suited to study the CIB to better precision and at larger scales than available so far. We propose to cross-correlate the Spitzer unresolved CIB to the unresolved CXB observed by Chandra and XMM-Newton. Chandra has covered the full 2 deg2 COSMOS

  18. The background simulations for the integral X-ray monitor JEM-X

    DEFF Research Database (Denmark)

    Feroci, M.; Rapisarda, M.; Costa, E.;

    1999-01-01

    The JEM-X experiment (Joint European X-ray Monitor, Lund et al. (1998) and Westergaard and Lund (1998)) is the X-ray monitor of the INTEGRAL satellite. It is a coded aperture, high pressure microstrip proportional counter. It will operate in the primary energy range from 3 to 35 keV (with...... and transported through a very detailed model of the JEM-X detector....... extensions up to 100 keV), covering the central 6.6 degrees (FWHM) of the fields of view of the Imager and Spectrometer experiments. In this paper we show the latest background prediction for JEM-X, obtained by a Monte Carlo simulation based on the codes MCNP and GEANT. The local radiation environment used...

  19. Piecing together the X-ray background: bolometric corrections for active galactic nuclei

    Science.gov (United States)

    Vasudevan, R. V.; Fabian, A. C.

    2007-11-01

    The X-ray background can be used to constrain the accretion history of supermassive black holes (SMBHs) in active galactic nuclei (AGN), with the SMBH mass density related to the energy density due to accretion. A knowledge of the hard X-ray bolometric correction, κ2-10keV, is a vital input into these studies, as it allows us to constrain the parameters of the accretion responsible for SMBH growth. Earlier studies assumed a constant bolometric correction for all AGN, and more recent work has suggested accounting for a dependence on AGN luminosity. Until recently, the variations in the disc emission in the ultraviolet (UV) have not been taken into account in this calculation; we show that such variations are important by construction of optical-to-X-ray spectral energy distributions for 54 AGN. In particular, we use Far Ultraviolet Spectroscopic Explorer (FUSE) UV and X-ray data from the literature to constrain the disc emission as well as possible. We find evidence for very significant spread in the bolometric corrections, with no simple dependence on luminosity being evident. Populations of AGN such as narrow-line Seyfert 1 nuclei, radio-loud and X-ray-weak AGN may have bolometric corrections which differ systematically from the rest of the AGN population. We identify other sources of uncertainty including intrinsic extinction in the optical-UV, X-ray and UV variability and uncertainties in SMBH mass estimates. Our results suggest a more well-defined relationship between the bolometric correction and Eddington ratio in AGN, with a transitional region at an Eddington ratio of ~0.1, below which the bolometric correction is typically 15-25, and above which it is typically 40-70. We consider the potential-implied parallels with the low/hard and high/soft states in Galactic black hole (GBH) accretion, and present bolometric corrections for the GBH binary GX 339-4 for comparison. Our findings reinforce previous studies proposing a multistate description of AGN

  20. X-ray detection with Micromegas with background levels below 10$^{-6}$ keV$^{-1}$cm$^{-2}$s$^{-1}$

    CERN Document Server

    Aune, S; Calvet, D.; Dafni, T.; Diago, A.; Druillole, F.; Fanourakis, G.; Ferrer-Ribas, E.; Galán, J.; García, J.A.; Gardikiotis, A.; Garza, J.G.; Geralis, T.; Giomataris, I.; Gómez, H.; González-Díaz, D.; Herrera, D.C.; Iguaz, F.J.; Irastorza, I.G.; Jourde, D.; Luzón, G.; Mirallas, H.; Mols, J.P.; Papaevangelou, T.; Rodríguez, A.; Seguí, L.; Tomás, A.; Vafeiadis, T.; Yildiz, S.C.

    2013-01-01

    Micromegas detectors are an optimum technological choice for the detection of low energy x-rays. The low background techniques applied to these detectors yielded remarkable background reductions over the years, being the CAST experiment beneficiary of these developments. In this document we report on the latest upgrades towards further background reductions and better understanding of the detectors' response. The upgrades encompass the readout electronics, a new detector design and the implementation of a more efficient cosmic muon veto system. Background levels below 10$^{-6}$keV$^{-1}$cm$^{-2}$s$^{-1}$ have been obtained at sea level for the first time, demonstrating the feasibility of the expectations posed by IAXO, the next generation axion helioscope. Some results obtained with a set of measurements conducted in the x-ray beam of the CAST Detector Laboratory will be also presented and discussed.

  1. Analysis of XMM-Newton Data from Extended Sources and the Diffuse X-Ray Background

    Science.gov (United States)

    Snowden, Steven

    2011-01-01

    Reduction of X-ray data from extended objects and the diffuse background is a complicated process that requires attention to the details of the instrumental response as well as an understanding of the multiple background components. We present methods and software that we have developed to reduce data from XMM-Newton EPIC imaging observations for both the MOS and PN instruments. The software has now been included in the Science Analysis System (SAS) package available through the XMM-Newton Science Operations Center (SOC).

  2. Employing a Cerenkov detector for the thickness measurement of X-rays in a scattering background

    Institute of Scientific and Technical Information of China (English)

    LI Shu-Wei; KANG Ke-Jun; WANG Yi; LI Jin; LI Yuan-Jing; ZHANG Qing-Jun

    2010-01-01

    The variation in environmental scattering background is a major source of systematic errors in X-ray inspection and measurement systems.As the energy of these photons consisting of environmental scattering background is much lower generally,the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence.A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison.Furthermore,it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.

  3. Chandra Discovers X-Ray Ring Around Cosmic Powerhouse in Crab Nebula

    Science.gov (United States)

    1999-09-01

    After barely two months in space, NASA's Chandra X-ray Observatory has taken a stunning image of the Crab Nebula, the spectacular remains of a stellar explosion, and has revealed something never seen before: a brilliant ring around the nebula's heart. Combined with observations from the Hubble Space Telescope, the image provides important clues to the puzzle of how the cosmic "generator," a pulsing neutron star, energizes the nebula, which still glows brightly almost 1,000 years after the explosion. "The inner ring is unique," said Professor Jeff Hester of Arizona State University, Tempe, AZ. "It has never been seen before, and it should tell us a lot about how the energy from the pulsar gets into the nebula. It's like finding the transmission lines between the power plant and the light bulb." Professor Mal Ruderman of Columbia University, New York, NY, agreed. "The X-rays Chandra sees are the best tracer of where the energy is. With images such as these, we can directly diagnose what is going on." What is going on, according to Dr. Martin Weisskopf, Chandra Project Scientist from NASA's Marshall Space Flight Center, Huntsville, AL, is awesome. "The Crab pulsar is accelerating particles up to the speed of light and flinging them out into interstellar space at an incredible rate." The image shows tilted rings or waves of high-energy particles that appear to have been flung outward over the distance of a light year from the central star, and high-energy jets of particles blasting away from the neutron star in a direction perpendicular to the spiral. Hubble Space Telescope images have shown moving knots and wisps around the neutron star, and previous X-ray images have shown the outer parts of the jet and hinted at the ring structure. With Chandra's exceptional resolution, the jet can be traced all the way in to the neutron star, and the ring pattern clearly appears. The image was made with Chandra's Advanced CCD Imaging Spectrometer and High Energy Transmission

  4. Testing the cosmic distance duality with X-ray gas mass fraction and supernovae data

    CERN Document Server

    Goncalves, R S; Alcaniz, J S

    2011-01-01

    In this paper we discuss a new cosmological model-independent test for the cosmic distance duality relation (CDDR), $\\eta = D_{L}(L)(1+z)^{-2}/D_{A}(z)=1$, where $D_{A}(z)$ and $D_{L}(z)$ are the angular and luminosity distances, respectively. Using the general expression for X-ray gas mass fraction ($f_{gas}$) of galaxy clusters, $f_{gas} \\propto D_L{D_A}^{1/2}$, we show that $f_{gas}$ observations jointly with type Ia supernovae (SNe Ia) data furnish a validity test for the CDDR. To perform our analysis we use 38 $f_{gas}$ measurements recently studied by two groups considering different assumptions to describe the clusters (La Roque {\\it{et al.}} 2006 and Ettori {\\it{et al.}} 2009) and two subsamples of SNe Ia distance lumonosity extracted from the Union2 compilation. In our test we consider the $\\eta$ parameter as a function of the redshift parameterized by two different functional forms. It is found that the La Roque {\\it{et al.}} (2006) sample is in perfect agreement with the duality relation ($\\eta = 1...

  5. Properties of the Diffuse X-ray Background toward MBM20 with Suzaku

    CERN Document Server

    Sen-Gupta, A; Koutroumpa, D; Smith, R; Lallement, R

    2009-01-01

    We used Suzaku observations of the molecular cloud MBM20 and a low neutral hydrogen column density region nearby to separate and characterize the foreground and background diffuse X-ray emission. A comparison with a previous observation of the same regions with XMM-Newton indicates a significant change in the foreground flux which is attributed to Solar Wind Charge eXchange (SWCX). The data have also been compared with previous results from similar "shadow" experiments and with a SWCX model to characterize its O VII and O VIII emission.

  6. Low background x-ray detection with Micromegas for axion research

    CERN Document Server

    Aune, S.; Dafni, T.; Davenport, M.; Fanourakis, G.; Ferrer-Ribas, E.; Galan, J.; Garcia, J.A.; Gardikiotis, A.; Geralis, T.; Giomataris, I.; Gomez, H.; Garza, J.G.; Herrera, D.C.; Iguaz, F.J.; Irastorza, I.G.; Jourde, D.; Luzon, G.; Mols, J.P.; Papaevangelou, T.; Rodriguez, A.; Ruz, J.; Segui, L.; Tomas, A.; Vafeiadis, T.; Yildiz, S.C.

    2014-01-01

    Axion helioscopes aim at the detection of solar axions through their conversion into x-rays in laboratory magnetic fields. The use of low background x-ray detectors is an essential component contributing to the sensitivity of these searches. Here we review the recent advances on Micromegas detectors used in the CERN Axion Solar Telescope (CAST) and proposed for the future International Axion Observatory (IAXO). The most recent Micromegas setups in CAST have achieved background levels of 1.5$\\times10^{-6}$\\ckcs, a factor of more than 100 lower than the ones obtained by the first generation of CAST detectors. This improvement is due to the development of active and passive shielding techniques, offline discrimination techniques allowed by highly granular readout patterns, as well as the use of radiopure detector components. The status of the intensive R&D to reduce the background levels will be described, including the operation of replica detectors in test benches and the detailed Geant4 simulation of the ...

  7. Compton Heating of the Intergalactic Medium by the Hard X-ray Background

    CERN Document Server

    Madau, P; Madau, Piero; Efstathiou, George

    1999-01-01

    High-resolution hydrodynamics simulations of the Ly-alpha forest in cold dark matter dominated cosmologies appear to predict line widths that are substantially narrower than those observed. Here we point out that Compton heating of the intergalactic gas by the hard X-ray background (XRB), an effect neglected in all previous investigations, may resolve this discrepancy. The rate of gain in thermal energy by Compton scattering will dominate over the energy input from hydrogen photoionization if the XRB energy density is 0.2x/ times higher than the energy density of the UV background at a given epoch, where x is the hydrogen neutral fraction in units of 1e-6 and is the mean X-ray photon energy in units of m_ec^2. The numerical integration of the time-dependent rate equations shows that the intergalactic medium approaches a temperature of about 20,000 K at z>3 in popular models for the redshift evolution of the extragalactic background radiation. The importance of Compton heating can be tested experimentally by ...

  8. The mass density in black holes inferred from the X-ray background

    CERN Document Server

    Fabian, A C

    1999-01-01

    The X-ray Background (XRB) probably originates from the integrated X-ray emission of active galactic nuclei (AGN). Modelling of its flat spectrum implies considerable absorption in most AGN. Compton down-scattering means that sources in which the absorption is Compton thick are unlikely to be major contributors to the background intensity so the observed spectral intensity at about 30 keV is little affected by photoelectric absorption. Assuming that the intrinsic photon index of AGN is 2, we then use the 30 keV intensity of the XRB to infer the absorption-corrected energy density of the background. Soltan's argument then enables us to convert this to a mean local density in black holes, assuming an accretion efficiency of 0.1 and a mean AGN redshift of 2. The result is within a factor of two of that estimated by Haehnelt et al from the optically-determined black hole masses of Magorrian et al. We conclude that there is no strong need for any radiatively inefficient mode of accretion for building the masses of...

  9. The Cosmic Infrared Background Experiment

    CERN Document Server

    Bock, J; Cooray, A R; Kawada, M; Keating, B; Lange, A; Lee, D H; Matsumoto, T; Matsuura, S; Pak, S; Renbarger, T; Sullivan, I; Tsumura, K; Wada, T; Watabe, T; Bock, James; Battle, John; Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hea; Matsumoto, Toshio; Matsuura, Shuji; Pak, Soojong; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Watabe, Toyoki

    2006-01-01

    We are developing a rocket-borne instrument (the Cosmic Infrared Background ExpeRiment, or CIBER) to search for signatures of primordial galaxy formation in the cosmic near-infrared extra-galactic background. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The cameras will search for spatial fluctuations in the background on angular scales from 7 arcseconds to 2 degrees over a range of angular scales poorly covered by previous experiments. CIBER will determine if the fluctuations reported by the IRTS arise from first-light galaxies or have a local origin. In a short rocket flight CIBER has sensitivity to probe fluctuations 100 times fainter than IRTS/DIRBE. By jointly observing regions of the sky studied by Spitzer and ASTRO-F, CIBER will build a multi-color view of the near-infrared background, accurately assessing the contribution of local (z = 1-3) galaxies to the observed background fluctuations, allowing a de...

  10. Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes

    CERN Document Server

    Brandt, W N

    2015-01-01

    We review results from cosmic X-ray surveys of active galactic nuclei (AGNs) over the past ~ 15 yr that have dramatically improved our understanding of growing supermassive black holes (SMBHs) in the distant universe. First, we discuss the utility of such surveys for AGN investigations and the capabilities of the missions making these surveys, emphasizing Chandra, XMM-Newton, and NuSTAR. Second, we briefly describe the main cosmic X-ray surveys, the essential roles of complementary multiwavelength data, and how AGNs are selected from these surveys. We then review key results from these surveys on the AGN population and its evolution ("demographics"), the physical processes operating in AGNs ("physics"), and the interactions between AGNs and their environments ("ecology"). We conclude by describing some significant unresolved questions and prospects for advancing the field.

  11. Cross-correlation between X-ray and optical/near-infrared background intensity fluctuations

    CERN Document Server

    Mitchell-Wynne, Ketron; Xue, Yongquan; Luo, Bin; Brandt, William; Koekemoer, Anton

    2016-01-01

    Angular power spectra of optical and infrared background anisotropies at wavelengths between 0.5 to 5 $\\mu$m are a useful probe of faint sources present during reionization, in addition to faint galaxies and diffuse signals at low redshift. The cross-correlation of these fluctuations with backgrounds at other wavelengths can be used to separate some of these signals. A previous study on the cross-correlation between X-ray and $Spitzer$ fluctuations at 3.6 $\\mu$m and 4.5 $\\mu$m has been interpreted as evidence for direct collapse blackholes (DCBHs) present at $z > 12$. Here we return to this cross-correlation and study its wavelength dependence from 0.5 to 4.5 $\\mu$m using $Hubble$ and $Spitzer$ data in combination with a subset of the 4 Ms $Chandra$ observations in GOODS-S/ECDFS. Our study involves five $Hubble$ bands at 0.6, 0.7, 0.85, 1.25 and 1.6 $\\mu$m, and two $Spitzer$-IRAC bands at 3.6 $\\mu$m and 4.5 $\\mu$m. We confirm the previously seen cross-correlation between 3.6 $\\mu$m (4.5 $\\mu$m) and X-rays wit...

  12. The Cosmic Background Explorer Satellite

    Science.gov (United States)

    Mather, J.; Kelsall, T.

    1980-01-01

    The Cosmic Background Explorer (COBE) satellite, planned for launch in 1985, will measure the diffuse infrared and microwave radiation of the universe over the entire wavelength range from a few microns to 1.3 cm. It will include three instruments: a set of microwave isotropy radiometers at 23, 31, 53, and 90 GHz, an interferometer spectrometer from 1 to 100/cm, and a filter photometer from 1 to 300 microns. The COBE satellite is designed to reach the sensitivity limits set by foreground sources such as the interstellar and interplanetary dust, starlight, and galactic synchrotron radiation, so that a diffuse residual radiation may be interpreted unambiguously as extragalactic

  13. Origins of the 1/4 keV Soft X-Ray Background

    CERN Document Server

    Bellm, E C; Bellm, Eric C.; Vaillancourt, John E.

    2005-01-01

    Snowden and coworkers have presented a model for the 1/4 keV soft X-ray diffuse background in which the observed flux is dominated by a ~ 10^6 K thermal plasma located in a 100-300 pc diameter bubble surrounding the Sun, but has significant contributions from a very patchy Galactic halo. Halo emission provides about 11% of the total observed flux and is responsible for half of the H I anticorrelation. The remainder of the anticorrelation is presumably produced by displacement of disk H I by the varying extent of the local hot bubble (LHB). The ROSAT R1 and R2 bands used for this work had the unique spatial resolution and statistical precision required for separating the halo and local components, but provide little spectral information. Some consistency checks had been made with older observations at lower X-ray energies, but we have made a careful investigation of the extent to which the model is supported by existing sounding rocket data in the Be (73-111 eV) and B bands (115-188 eV) where the sensitivities...

  14. Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background

    CERN Document Server

    Crowder, S G; Brandl, D E; Eckart, M E; Galeazzi, M; Kelley, R L; Kilbourne, C A; McCammon, D; Pfendner, C G; Porter, F S; Rocks, L; Szymkowiak, A E; Teplin, I M

    2012-01-01

    We present a high resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for a ~1 region of the sky centered at l=90, b=+60 using a 36-pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568+2-3 eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV while for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex, consistent with much of the high-latitude O VII emission originating in 2-3 x 10^6 K gas in the Galactic halo. On the other hand, the observed ratio of C VI Ly gamma to Ly alpha is...

  15. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, John P., E-mail: john.sutter@diamond.ac.uk; Dolbnya, Igor P.; Collins, Stephen P. [Diamond Light Source Ltd., Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Harris, Kenneth D. M.; Edwards-Gau, Gregory R. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Palmer, Benjamin A. [Department of Structural Biology, Weizmann Institute of Science, 234 Herzl St., Rehovot 7610001 (Israel)

    2015-04-28

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  16. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    Science.gov (United States)

    Sutter, John P.; Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-01

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  17. How the first generations of luminous baryons established the X-ray and UV backgrounds

    CERN Document Server

    Mesinger, Andrei

    2011-01-01

    The first generations of astrophysical objects made a substantial impact on our Universe with their radiation. X-rays from the first sources, with large mean free paths, likely quickly heated the intergalactic medium (IGM). The second generation of 21cm instruments can provide a unique view into this early epoch. The early stages of reionization likely followed, driven by so-called "minihalos", i.e. molecularly-cooled halos. These small halos were susceptible to complex feedback mechanisms, especially from the soft-UV background which preceded reionization, resulting in complex and possibly extended early stages of reionization. When atomically-cooled galaxies emerged as the dominant ionizers, reionization could proceed more rapidly, with these being less sensitive to radiative feedback than previously thought. Reionization could have slowed in the final stages when the ionized bubbles grew larger than the separation of Lyman limit absorption systems (LLSs). The final stages likely involved the photo-evaporat...

  18. Background and Imaging Simulations for the Hard X-Ray Camera of the MIRAX Mission

    CERN Document Server

    Castro, Manuel; Penacchioni, Ana; D'Amico, Flavio; Sacahui, Rodrigo

    2016-01-01

    We report the results of detailed Monte Carlo simulations of the performance expected both at balloon altitudes and at the probable satellite orbit of a hard X-ray coded-aperture camera being developed for the {\\it MIRAX\\/} mission. Based on a thorough mass model of the instrument and detailed specifications of the spectra and angular dependence of the various relevant radiation fields at both the stratospheric and orbital environments, we have used the well-known package GEANT4 to simulate the instrumental background of the camera. We also show simulated images of source fields to be observed and calculated the detailed sensitivity of the instrument in both situations. The results reported here are especially important to researchers in this field considering that we provide important information, not easily found in the literature, on how to prepare input files and calculate crucial instrumental parameters to perform GEANT4 simulations for high-energy astrophysics space experiments.

  19. Background and imaging simulations for the hard X-ray camera of the MIRAX mission

    Science.gov (United States)

    Castro, M.; Braga, J.; Penacchioni, A.; D'Amico, F.; Sacahui, R.

    2016-07-01

    We report the results of detailed Monte Carlo simulations of the performance expected both at balloon altitudes and at the probable satellite orbit of a hard X-ray coded-aperture camera being developed for the Monitor e Imageador de RAios X (MIRAX) mission. Based on a thorough mass model of the instrument and detailed specifications of the spectra and angular dependence of the various relevant radiation fields at both the stratospheric and orbital environments, we have used the well-known package GEANT4 to simulate the instrumental background of the camera. We also show simulated images of source fields to be observed and calculated the detailed sensitivity of the instrument in both situations. The results reported here are especially important to researchers in this field considering that we provide important information, not easily found in the literature, on how to prepare input files and calculate crucial instrumental parameters to perform GEANT4 simulations for high-energy astrophysics space experiments.

  20. A focussing iron line crystal spectrometer for Spacelab. [cosmic X-ray detection

    Science.gov (United States)

    Catura, R. C.; Culhane, J. L.; Rapley, C. G.; Gabriel, A. H.; Walker, A. B. C., Jr.; Woodgate, B. E.

    1977-01-01

    A crystal spectrometer system is described which employs conical focusing of 12 curved LiF crystal panels to minimize the detector size and reduce the background counting rate. The wavelength range from 1.70 to 1.98 A is covered, including the resonance lines of Fe XXV and Fe XXVI as well as the Fe I K-alpha line and absorption edge. Operation of the spectrometer is discussed, noting that diffracted X-rays are registered in one-dimensional position-sensitive detectors and that the arrival position of a photon in a detector is related to its wavelength due to the fixed curvature of the crystal panels in the dispersion plane. Some characteristics of the multianode position-sensitive detectors are reviewed along with the crystal arrangement and mounting. The instrument sensitivity is evaluated in relation to the strengths of 6.7-keV emission features detected by the Ariel 5 and OSO 8 proportional-counter spectrometers.

  1. In-orbit background of X-ray microcalorimeters and its effects on observations

    CERN Document Server

    Lotti, S; Macculi, C; Mineo, T; Natalucci, L; Perinati, E; Piro, L; Federici, M; Martino, B

    2014-01-01

    Methods.There are no experimental data about the background experienced by microcalorimeters in the L2 orbit, and thus the particle background levels were calculated by means of Monte Carlo simulations: we considered the original design configuration and an improved configuration aimed to reduce the unrejected background, and tested them in the L2 orbit and in the low Earth orbit, comparing the results with experimental data reported by other X-ray instruments.To show the results obtainable with the improved configuration we simulated the observation of a faint, high-redshift, point source (F[0.5-10 keV]~6.4E-16 erg cm-2 s-1, z=3.7), and of a hot galaxy cluster at R200 (Sb[0.5-2 keV]=8.61E-16 erg cm-2 s-1 arcmin-2,T=6.6 keV). Results.First we confirm that implementing an active cryogenic anticoincidence reduces the particle background by an order of magnitude and brings it close to the required level.The implementation and test of several design solutions can reduce the particle background level by a further ...

  2. From zone plate to microcalorimeter . 50 years of cosmic X-ray spectroscopy at SRON

    Science.gov (United States)

    Bleeker, J.; Verbunt, F.

    The first method used by the SRON Laboratory for Space Research at Utrecht to spectroscopically image the Sun in X-rays employed Fresnel zone plates. Four Fresnel plates, covering four specific wavelengths, were flown on an Aerobee rocket in 1967 and gave a first useful X-ray image of the Sun in the Si-X line at 51 Å. The technique developed for the solar X-ray images enabled SRON to become the Lead Investigator for the grating spectrographs on several major X-ray satellites, i.e. on the Einstein and EXOSAT satellites, launched in November 1978 and May 1983 respectively, and on the Chandra and XMM-Newton observatories both launched in 1999. Since then, a considerable effort was put into the development of cryogenically cooled, non-dispersive X-ray spectrometers as model payload elements for the XEUS, IXO and Athena mission studies. This paper briefly reviews these developments, highlights some of the resulting scientific insights and offers a few thoughts on the present outlook for a next generation X-ray observatory. The biggest challenge for the realization of such a mission is not primarily technical: global coordination and collaboration, both among scientists and the major space agencies, is a prerequisite for a successful next major leap in this discipline.

  3. Study of the properties of Cosmic rays and solar X-Ray Flares by balloon borne experiments

    CERN Document Server

    Chakrabarti, S K; Chakraborty, S; Palit, S; Mondal, S K; Bhattacharya, A; Midya, S; Chakrabarti, S

    2013-01-01

    Indian Centre for Space Physics is engaged in pioneering balloon borne experiments with typical payloads less than ~ 3.5kg. Low cost rubber balloons are used to fly them to a height of about 40km. In a double balloon system, the booster balloon lifts the orbiter balloon to its cruising altitude where data is taken for a longer period of time. In this Paper, we present our first scientific report on the variation of Cosmic Rays and muons with altitude and detection of several solar flares in X-rays between 20keV and 100keV. We found the altitude of the Pfotzer maximum at Tropic of Cancer for cosmic rays and muons and catch several solar flares in hard X-rays. We find that the hard X-ray (> 40keV) sky becomes very transparent above Pfotzer maximum. We find the flare spectrum to have a power-law distribution. From these studies, we infer that valuable scientific research could be carried out in near space using low cost balloon borne experiments. Published in Online version of Indian Journal of Physics.

  4. Polarization of Cosmic Microwave Background

    CERN Document Server

    Buzzelli, Alessandro; de Gasperis, Giancarlo; Vittorio, Nicola

    2016-01-01

    In this work we present an extension of the ROMA map-making code for data analysis of Cosmic Microwave Background polarization, with particular attention given to the inflationary polarization B-modes. The new algorithm takes into account a possible cross-correlated noise component among the different detectors of a CMB experiment. We tested the code on the observational data of the BOOMERanG (2003) experiment and we show that we are provided with a better estimate of the power spectra, in particular the error bars of the BB spectrum are smaller up to 20% for low multipoles. We point out the general validity of the new method. A possible future application is the LSPE balloon experiment, devoted to the observation of polarization at large angular scales.

  5. An Einstein survey of the 1 keV soft X-ray background in the Galactic plane

    Science.gov (United States)

    Stanford, John M.; Caillault, Jean-Pierre

    1994-01-01

    We have analyzed 56 Einstein Observatory Imaging Proportional Counter (IPC) observations within +/- 3 deg of the Galactic plane in order to determine the low-latitude soft X-ray background flux in the 0.56-1.73 keV band. Any detected X-ray point source which fell within our regions of study was removed from the image, enabling us to present maps of the background flux as a function of Galactic latitude along 18 meridians. These maps reveal considerable structure to the background in the Galactic plane on an angular scale of approximately 1 deg. Our results are compared with those of an earlier study of the 1 keV X-ray background along l = 25 deg by Kahn & Caillault. The double-peaked structure they found is not discernible in our results, possibly because of the presence of solar backscattered flux in their data. A model which takes into account contributions to the background by extragalactic and stellar sources, the distribution of both atomic and molecular absorbing material with the Galaxy, the energy dependence of the cross section for absorption of X-rays, and the energy dependence of the detector has been constructed and fitted to these new data to derive constraints on the scale height, temperature, and volume emissivity of the unaccounted-for X-ray-emitting material. The results of this model along l = 25 deg are roughly similar to those of the model of Kahn & Caillault along the same meridian.

  6. A High Spectral Resolution Observation of the Soft X-ray Diffuse Background with Thermal Detectors

    CERN Document Server

    McCammon, D; Apodaca, E; Tiest, W B; Cui, W; Deiker, S W; Galeazzi, M; Juda, M; Lesser, A; Mihara, T; Morgenthaler, J P; Sanders, W T; Zhang, J; Figueroa-Feliciano, E; Kelley, R L; Moseley, S H; Mushotzky, R F; Porter, F S; Stahle, C K; Szymkowiak, A E

    2002-01-01

    A high spectral resolution observation of the diffuse X-ray background in the 60 - 1000 eV energy range has been made using an array of thirty-six 1 mm^2 micro-calorimeters flown on a sounding rocket. Detector energy resolution ranged from 5-12 eV FWHM, and a composite spectrum of ~ 1 steradian of the background centered at l = 90, b = +60 was obtained with a net resolution of ~ 9 eV. The target area includes bright 1/4 keV regions, but avoids Loop I and the North Polar Spur. Lines of C VI, O VII, and O VIII are clearly detected with intensities of 5.4 +/- 2.3, 4.8 +/- 0.8, and 1.6 +/- 0.4 photons cm^-2 s^-1 sr^-1, respectively. The oxygen lines alone account for a majority of the diffuse background observed in the ROSAT R4 band that is not due to resolved extragalactic discrete sources. We also have a positive detection of the Fe-M line complex near 70 eV at an intensity consistent with previous upper limits that indicate substantial gas phase depletion of iron. We include a detailed description of the instr...

  7. The contribution of galaxy clusters to the soft X-ray background

    Science.gov (United States)

    Blanchard, A.; Wachter, K.; Evrard, A. E.; Silk, Joseph

    1992-01-01

    The present paper examines models for the expected contribution to the X-ray background (XRB) from clusters of galaxies in a flat universe with a spectrum of fluctuations corresponding to the standard cold dark matter picture and for a power-law spectrum P(k) varies as k sup n with n = -2. A self-similar scaling model for clusters proposed by Kaiser (1986) is presented, along with several variants. Photon statistics from synthesized maps of deep Einstein fields show a granularity similar to that deduced by Hamilton and Helfand (1987) from the Einstein data but overproduces by a large factor the number of discrete sources observed as clusters, and the fluctuation limit derived from the recent correlation analyses of the background. Two alternative models are designed to be consistent with the local luminosity function data; for these, expected deep images for the Rosat satellite are generated. Clusters of galaxies should be a significant source of background at energies around 2 keV, and it is proposed that clusters of galaxies contribute up to 30 percent of the unresolved component.

  8. The Cosmic Infrared Background Experiment

    Science.gov (United States)

    Bock, James; Battle, J.; Cooray, A.; Hristov, V.; Kawada, M.; Keating, B.; Lee, D.; Matsumoto, T.; Matsuura, S.; Nam, U.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2009-01-01

    We are developing the Cosmic Infrared Background ExpeRiment (CIBER) to search for signatures of first-light galaxy emission in the extragalactic background. The first generation of stars produce characteristic signatures in the near-infrared extragalactic background, including a redshifted Ly-cutoff feature and a characteristic fluctuation power spectrum, that may be detectable with a specialized instrument. CIBER consists of two wide-field cameras to measure the fluctuation power spectrum, and a low-resolution and a narrow-band spectrometer to measure the absolute background. The cameras will search for fluctuations on angular scales from 7 arcseconds to 2 degrees, where the first-light galaxy spatial power spectrum peaks. The cameras have the necessary combination of sensitivity, wide field of view, spatial resolution, and multiple bands to make a definitive measurement. CIBER will determine if the fluctuations reported by Spitzer arise from first-light galaxies. The cameras observe in a single wide field of view, eliminating systematic errors associated with mosaicing. Two bands are chosen to maximize the first-light signal contrast, at 1.6 um near the expected spectral maximum, and at 1.0 um; the combination is a powerful discriminant against fluctuations arising from local sources. We will observe regions of the sky surveyed by Spitzer and Akari. The low-resolution spectrometer will search for the redshifted Lyman cutoff feature in the 0.7 - 1.8 um spectral region. The narrow-band spectrometer will measure the absolute Zodiacal brightness using the scattered 854.2 nm Ca II Fraunhofer line. The spectrometers will test if reports of a diffuse extragalactic background in the 1 - 2 um band continues into the optical, or is caused by an under estimation of the Zodiacal foreground. We report performance of the assembled and tested instrument as we prepare for a first sounding rocket flight in early 2009. CIBER is funded by the NASA/APRA sub-orbital program.

  9. A Cosmic Microwave Background feature consistent with a cosmic texture

    OpenAIRE

    Cruz, M.; Turok, N.; Vielva, P.; Martinez-Gonzalez, E.; Hobson, M.

    2007-01-01

    The Cosmic Microwave Background provides our most ancient image of the Universe and our best tool for studying its early evolution. Theories of high energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent, 5 degree radius cold spot observed in all-sky images, which is otherw...

  10. Can we reproduce the X-ray background spectral shape using local AGN?

    CERN Document Server

    Vasudevan, Ranjan V; Gandhi, Poshak

    2013-01-01

    The X-ray background (XRB) is due to the aggregate of active galactic nuclei (AGN), which peak in activity at z~1 and is often modeled as the sum of different proportions of unabsorbed, moderately- and heavily-absorbed AGN. We present the summed spectrum of a complete sample of local AGN (the Northern Galactic Cap of the 58-month Swift/BAT catalog, z<0.2) using 0.4-200keV data and directly determine the different proportions of unabsorbed, moderately and heavily-absorbed AGN that make up the summed spectrum. This stacked low redshift AGN spectrum is remarkably similar in shape to the XRB spectrum (when shifted to z~1), but the observed proportions of different absorption populations differ from most XRB synthesis models. AGN with Compton-thick absorption account for only ~12% of the sample, but produce a significant contribution to the overall spectrum. We confirm that Compton reflection is more prominent in moderately-absorbed AGN and that the photon index differs intrinsically between unabsorbed and abso...

  11. CAN WE REPRODUCE THE X-RAY BACKGROUND SPECTRAL SHAPE USING LOCAL ACTIVE GALACTIC NUCLEI?

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Ranjan V.; Mushotzky, Richard F. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Gandhi, Poshak, E-mail: ranjan@astro.umd.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2013-06-20

    The X-ray background (XRB) is due to the aggregate of active galactic nuclei (AGNs), which peak in activity at z {approx} 1 and is often modeled as the sum of different proportions of unabsorbed, moderately, and heavily absorbed AGN. We present the summed spectrum of a complete sample of local AGN (the Northern Galactic Cap of the 58 month Swift/BAT catalog, z < 0.2) using 0.4-200 keV data and directly determine the different proportions of unabsorbed, moderately and heavily absorbed AGN that make up the summed spectrum. This stacked low redshift AGN spectrum is remarkably similar in shape to the XRB spectrum (when shifted to z {approx} 1), but the observed proportions of different absorption populations differ from most XRB synthesis models. AGN with Compton-thick absorption account for only {approx}12% of the sample, but produce a significant contribution to the overall spectrum. We confirm that Compton reflection is more prominent in moderately absorbed AGN and that the photon index differs intrinsically between unabsorbed and absorbed AGN. The AGN in our sample account for only {approx}1% of the XRB intensity. The reproduction of the XRB spectral shape suggests that strong evolution in individual AGN properties is not required between z {approx} 0 and 1.

  12. The Temperature of the Cosmic Microwave Background

    CERN Document Server

    Fixsen, D J

    2009-01-01

    The FIRAS data are independently recalibrated using the WMAP data to obtain a CMB temperature of 2.7260 +/- 0.0013. Measurements of the temperature of the cosmic microwave background are reviewed. The determination from the measurements from the literature is cosmic microwave background temperature of 2.72548 +/- 0.00057 K.

  13. Relativistic ejecta from X-ray flash XRF 060218 and the rate of cosmic explosions.

    Science.gov (United States)

    Soderberg, A M; Kulkarni, S R; Nakar, E; Berger, E; Cameron, P B; Fox, D B; Frail, D; Gal-Yam, A; Sari, R; Cenko, S B; Kasliwal, M; Chevalier, R A; Piran, T; Price, P A; Schmidt, B P; Pooley, G; Moon, D-S; Penprase, B E; Ofek, E; Rau, A; Gehrels, N; Nousek, J A; Burrows, D N; Persson, S E; McCarthy, P J

    2006-08-31

    Over the past decade, long-duration gamma-ray bursts (GRBs)--including the subclass of X-ray flashes (XRFs)--have been revealed to be a rare variety of type Ibc supernova. Although all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary type Ibc supernovae by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just a supernova, is still unknown. Here we report radio and X-ray observations of XRF 060218 (associated with supernova SN 2006aj), the second-nearest GRB identified until now. We show that this event is a hundred times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary type Ibc supernovae by the presence of 10(48) erg coupled to mildly relativistic ejecta, along with a central engine (an accretion-fed, rapidly rotating compact source) that produces X-rays for weeks after the explosion. This suggests that the production of relativistic ejecta is the key physical distinction between GRBs or XRFs and ordinary supernovae, while the nature of the central engine (black hole or magnetar) may distinguish typical bursts from low-luminosity, spherical events like XRF 060218.

  14. The impact of the in-orbit background and the X-ray source intensity on the centroiding accuracy of the Swift X-ray telescope

    Science.gov (United States)

    Ambrosi, R. M.; Hutchinson, I. B.; Hill, J.; Cheruvu, C.; Abbey, A. F.; Short, A. D. T.

    2002-11-01

    The optical components of the Swift Gamma Ray Burst Explorer X-ray Telescope (XRT), consisting of the JET-X spare flight mirror and a charge coupled device of the type used in the EPIC program, were used in a re-calibration study carried out at the Panter facility, which is part of the Max Plank Institute for Extraterrestrial Physics. The objective of this study was to check the focal length and the off axis performance of the mirrors and to show that the half energy width (HEW) of the on-axis point spread function (PSF) was of the order of 16arcsec at 1.5keV (Nucl. Instr. and Meth. A 488 (2002) 543; SPIE 4140 (2000) 64) and that a centroiding accuracy better that 1arcsec could be achieved within the 4arcmin sampling area designated by the Burst Alert Telescope (Nucl. Instr. and Meth. A 488 (2002) 543). The centroiding accuracy of the Swift XRT's optical components was tested as a function of distance from the focus and off axis position of the PSF (Nucl. Instr. and Meth. A 488 (2002) 543). The presence of background events in the image frame introduced errors in the centroiding process, making the choice of centroiding algorithm important (Nucl. Instr. and Meth. A 488 (2002) 543). Since the objective of Swift is to rapidly investigate the X-ray afterglows of Gamma Ray Bursts the possibility of detecting a bright source with intensity greater than 25 Crab could not be excluded and therefore the impact of a saturated PSF core on the centroiding accuracy was investigated by experimental methods.

  15. Cosmic Microwave Background Data Analysis

    Science.gov (United States)

    Paykari, Paniez; Starck, Jean-Luc Starck

    2012-03-01

    About 400,000 years after the Big Bang the temperature of the Universe fell to about a few thousand degrees. As a result, the previously free electrons and protons combined and the Universe became neutral. This released a radiation which we now observe as the cosmic microwave background (CMB). The tiny fluctuations* in the temperature and polarization of the CMB carry a wealth of cosmological information. These so-called temperature anisotropies were predicted as the imprints of the initial density perturbations which gave rise to the present large-scale structures such as galaxies and clusters of galaxies. This relation between the present-day Universe and its initial conditions has made the CMB radiation one of the most preferred tools to understand the history of the Universe. The CMB radiation was discovered by radio astronomers Arno Penzias and Robert Wilson in 1965 [72] and earned them the 1978 Nobel Prize. This discovery was in support of the Big Bang theory and ruled out the only other available theory at that time - the steady-state theory. The crucial observations of the CMB radiation were made by the Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite [86]- orbited in 1989-1996. COBE made the most accurate measurements of the CMB frequency spectrum and confirmed it as being a black-body to within experimental limits. This made the CMB spectrum the most precisely measured black-body spectrum in nature. The CMB has a thermal black-body spectrum at a temperature of 2.725 K: the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9mmwavelength. The results of COBE inspired a series of ground- and balloon-based experiments, which measured CMB anisotropies on smaller scales over the next decade. During the 1990s, the first acoustic peak of the CMB power spectrum (see Figure 5.1) was measured with increasing sensitivity and by 2000 the BOOMERanG experiment [26] reported

  16. The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes

    Science.gov (United States)

    Fioretti, V.; Bulgarelli, A.; Malaguti, G.; Bianchin, V.; Trifoglio, M.; Gianotti, F.

    2012-07-01

    The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.

  17. Constraining the UV emissivity of AGN throughout cosmic time via X-ray surveys

    CERN Document Server

    Ricci, F; Shankar, F; La Franca, F; Civano, F

    2016-01-01

    The cosmological process of hydrogen (HI) reionization in the intergalactic medium is thought to be driven by UV photons emitted by star-forming galaxies and ionizing active galactic nuclei (AGN). The contribution of QSOs to HI reionization at $z>4$ has been traditionally believed to be quite modest. However, this view has been recently challenged by new estimates of a higher faint-end UV luminosity function (LF). To set firmer constraints on the emissivity of AGN at $z<6$, we here make use of complete X-ray selected samples including deep Chandra and new COSMOS data, capable to efficiently measure the 1 ryd comoving AGN emissivity up to $z\\sim5-6$ and down to five magnitudes fainter than probed by current optical surveys, without any luminosity extrapolation. We find good agreement between the logN$\\rm{_H}\\lesssim21-22$ cm$^{-2}$ X-ray LF and the optically-selected QSO LF at all redshifts for $M_{1450}\\leq -23$. The full range of the logN$\\rm{_H}\\lesssim21-22$ cm$^{-2}$ LF ($M_{1450} \\leq -17$) was then u...

  18. X-ray Hotspot Flares and Implications for Cosmic Ray Acceleration and Magnetic Field amplification in Supernova Remnants

    CERN Document Server

    Butt, Yousaf; Katz, Boaz; Waxman, Eli

    2008-01-01

    For more than fifty years, it has been believed that cosmic ray (CR) nuclei are accelerated to high energies in the rapidly expanding shockwaves created by powerful supernova explosions. Yet observational proof of this conjecture is still lacking. Recently, Uchiyama and collaborators reported the detection of small-scale X-ray flares in one such supernova remnant, dubbed 'RX J1713-3946' (a.k.a. G347.3-0.5), which also emits very energetic, TeV (10^12 eV) range, gamma-rays. They contend that the variability of these X-ray 'hotspots' implies that the magnetic field in the remnant is about a hundred times larger than normally assumed; and this, they say, means that the detected TeV range photons were produced in energetic nuclear interactions, providing 'a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10^15 eV) and beyond in young supernova remnants.' We point out here that the existing multiwavelength data on this object certainly do not support such conclusions. Though intriguing...

  19. OVII and OVIII line emission in the diffuse soft X-ray background: heliospheric and galactic contributions

    CERN Document Server

    Koutroumpa, D; Lallement, R; Ballet, J; Kharchenko, V

    2007-01-01

    We study the 0.57 keV (O VII triplet) and 0.65 keV (O VIII) diffuse emission generated by charge transfer collisions between solar wind (SW) oxygen ions and interstellar H and He neutral atoms in the inner Heliosphere. These lines which dominate the 0.3-1.0 keV energy interval are also produced by hot gas in the galactic halo (GH) and possibly the Local Interstellar Bubble (LB). We developed a time-dependent model of the SW Charge-Exchange (SWCX) X-ray emission, based on the localization of the SW Parker spiral at each instant. We include input SW conditions affecting three selected fields, as well as shadowing targets observed with XMM-Newton, Chandra and Suzaku and calculate X-ray emission fot O VII and O VIII lines. We determine SWCX contamination and residual emission to attribute to the galactic soft X-ray background. We obtain ground level intensities and/or simulated lightcurves for each target and compare to X-ray data. The local 3/4 keV emission (O VII and O VIII) detected in front of shadowing cloud...

  20. Constraining the fraction of Compton-thick AGN in the Universe by modelling the diffuse X-ray background spectrum

    CERN Document Server

    Akylas, A; Georgantopoulos, I; Brightman, M; Nandra, K

    2012-01-01

    This paper investigates what constraints can be placed on the fraction of Compton-thick (CT) AGN in the Universe from the modeling of the spectrum of the diffuse X-ray background (XRB). We present a model for the synthesis of the XRB that uses as input a library of AGN X-ray spectra generated by the Monte Carlo simulations described by Brightman & Nandra. This is essential to account for the Compton scattering of X-ray photons in a dense medium and the impact of that process on the spectra of obscured AGN. We identify a small number of input parameters to the XRB synthesis code which encapsulate the minimum level of uncertainty in reconstructing the XRB spectrum. These are the power-law index and high energy cutoff of the intrinsic X-ray spectra of AGN, the level of the reflection component in AGN spectra and the fraction of CT AGN in the Universe. We then map the volume of the space allowed to these parameters by current observations of the XRB spectrum in the range 3-100 keV. One of the least constraine...

  1. Upper Limit on Dimming of Cosmological Sources by Intergalactic Grey Dust from the Soft X-ray Background

    CERN Document Server

    Dijkstra, Mark

    2009-01-01

    Active Galactic Nuclei (AGN) produce a dominant fraction (~80%) of the Soft X-ray background (SXB) at photon energies 0.5X-ray halos around AGN. Taking account of known galaxies and galaxy clusters, only a fraction F_halo <10% of the SXB can be in the form of diffuse X-ray halos around AGN. We therefore limit the intergalactic opacity to optical/infrared photons from large dust grains (with radii in the range a=0.2-2.0 mum) to a level tau_GD<0.15(F_halo/10%) to a redshift z~1. Our results are only weakly dependent on the grain size distribution or the redshift evolution of the intergalactic dust. Stacking X-ray images of AGN can be used to improve our constraints and diminish the importance of dust as a source of systematic uncertainty for future supernova surveys which aim to improve the precision on measuring the redshift evolution of the dark energy equation-of-state.

  2. Contribution of Unresolved Point Sources to the Diffuse X-ray Background below 1 keV

    CERN Document Server

    Gupta, Anjali

    2009-01-01

    We present here the analysis of X-rays point sources detected in several observations available in the XMM-Newton public archive. We focused, in particular, on energies below 1 keV, which are of particular relevance to the understanding of the Diffuse X-ray Background. The average field of all the exposures is 0.09 deg^-2. We reached an average flux sensitivity of 5.8x10^-16 erg s^-1 cm^-2 in the soft band (0.5-2.0 keV) and 2.5x10^-16 erg s^-1 cm^-2 in the very soft band (0.4-0.6 keV). In this paper we discuss the logN-logS results, the contribution to the integrated X-ray sky flux, and the properties of the cumulative spectrum from all sources. In particular, we found an excess flux at around 0.5 keV in the composite spectrum of faint sources. The excess seems to be a general property of all the fields observed suggesting an additional class of weak sources is contributing to the X-ray emission at these energies. Combining our results with previous investigations we have also quantified the contribution of t...

  3. X-ray spectroscopy of clusters of galaxies and of the cosmic web

    NARCIS (Netherlands)

    Werner, N.

    2008-01-01

    I present the results on the study of the chemical evolution of the intra-cluster medium (ICM) and on the evolution of clusters of galaxies in the context of the cosmic web. Clusters of galaxies are excellent laboratories to study the chemical enrichment history of the Universe. This thesis presents

  4. A cosmic microwave background feature consistent with a cosmic texture.

    Science.gov (United States)

    Cruz, M; Turok, N; Vielva, P; Martínez-González, E; Hobson, M

    2007-12-07

    The Cosmic Microwave Background provides our most ancient image of the universe and our best tool for studying its early evolution. Theories of high-energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture, which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent 5 degrees -radius cold spot observed in all-sky images, which is otherwise hard to explain, is compatible with having being caused by a texture. From this model, we constrain the fundamental symmetry-breaking energy scale to be (0) approximately 8.7 x 10(15) gigaelectron volts. If confirmed, this detection of a cosmic defect will probe physics at energies exceeding any conceivable terrestrial experiment.

  5. An X-ray view of quasars

    CERN Document Server

    Singh, K P

    2013-01-01

    I present an overview of observational studies of quasars of all types, with particular emphasis on X-ray observational studies. The presentation is based on the most popularly accepted unified picture of quasars - collectively referred to as AGN (active galactic nuclei) in this review. Characteristics of X-ray spectra and X-ray variability obtained from various X-ray satellites over the last 5 decades have been presented and discussed. The contribution of AGN in understanding the cosmic X-ray background is discussed very briefly. Attempt has been made to provide up-to-date information; however, this is a vast subject and this presentation is not intended to be comprehensive.

  6. Cosmic-Ray Acceleration at the Forward Shock in Tycho's Supernova Remnant: Evidence from Chandra X-Ray Observations

    Science.gov (United States)

    Warren, Jessica S.; Hughes, John P.; Badenes, Carles; Ghavamian, Parviz; McKee, Christopher F.; Moffett, David; Plucinsky, Paul P.; Rakowski, Cara; Reynoso, Estela; Slane, Patrick

    2005-11-01

    We present evidence for cosmic-ray acceleration at the forward shock in Tycho's supernova remnant (SNR) from three X-ray observables: (1) the proximity of the contact discontinuity to the forward shock, or blast wave, (2) the morphology of the emission from the rim of Tycho, and (3) the spectral nature of the rim emission. We determine the locations of the blast wave (BW), contact discontinuity (CD), and reverse shock (RS) around the rim of Tycho's supernova remnant using a principal component analysis and other methods applied to new Chandra data. The azimuthal-angle-averaged radius of the BW is 251". For the CD and RS we find average radii of 241" and 183", respectively. Taking account of projection effects, we find ratios of 1:0.93:0.70 (BW:CD:RS). We show these values to be inconsistent with adiabatic hydrodynamic models of SNR evolution. The CD:BW ratio can be explained if cosmic-ray acceleration of ions is occurring at the forward shock. The RS:BW ratio, as well as the strong Fe Kα emission from the Tycho ejecta, imply that the RS is not accelerating cosmic rays. We also extract radial profiles from ~34% of the rim of Tycho and compare them to models of surface brightness profiles behind the BW for a purely thermal plasma with an adiabatic shock. The observed morphology of the rim is much more strongly peaked than predicted by the model, indicating that such thermal emission is implausible here. Spectral analysis also implies that the rim emission is nonthermal in nature, lending further support to the idea that Tycho's forward shock is accelerating cosmic rays.

  7. Cosmic Ray Acceleration at the Forward Shock in Tycho's Supernova Remnant: Evidence from Chandra X-ray Observations

    CERN Document Server

    Warren, J S; Badenes, C; Ghavamian, P; McKee, C F; Moffett, D; Plucinsky, P P; Rakowski, C; Reynoso, E; Slane, P O

    2005-01-01

    We present evidence for cosmic ray acceleration at the forward shock in Tycho's supernova remnant (SNR) from three X-ray observables: (1) the proximity of the contact discontinuity to the forward shock, or blast wave, (2) the morphology of the emission from the rim of Tycho, and (3) the spectral nature of the rim emission. We determine the locations of the blast wave (BW), contact discontinuity (CD), and reverse shock (RS) around the rim of Tycho's supernova remnant using a principal component analysis and other methods applied to new Chandra data. The azimuthal-angle-averaged radius of the BW is 251". For the CD and RS we find average radii of 241" and 183", respectively. Taking account of projection effects, we find ratios of 1:0.93:0.70 (BW:CD:RS). We show these values to be inconsistent with adiabatic hydrodynamical models of SNR evolution. The CD:BW ratio can be explained if cosmic ray acceleration of ions is occurring at the forward shock. The RS:BW ratio, as well as the strong Fe Ka emission from the T...

  8. Can one measure the Cosmic Neutrino Background?

    CERN Document Server

    Faessler, Amand; Kovalenko, Sergey; Simkovic, Fedor

    2016-01-01

    The Cosmic Microwave Background (CMB) yields information about our Universe at around 380 000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the Big Bang. Probably the most promising method to `see' the Cosmic Neutrino Background is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562 keV plus the electron neutrino rest mass. The `KArlsruhe TRItium Neutrino' (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time KATRIN can also look by the reaction: electron neutrino (~1.95 Kelvin) + 3H --> 3He + e- (with the energy Q = 18.6 keV + electron neutrino mass). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spe...

  9. Cosmic X-rays Reveal Evidence For New Form Of Matter

    Science.gov (United States)

    2002-04-01

    NASA's Chandra X-ray Observatory has found two stars -- one too small, one too cold -- that reveal cracks in our understanding of the structure of matter. These discoveries open a new window on nuclear physics, offering a link between the vast cosmos and its tiniest constituents. Chandra's observations of RX J1856.5-3754 and 3C58 suggest that the matter in these stars is even denser than nuclear matter found on Earth. This raises the possibility these stars are composed of pure quarks or contain crystals of sub-nuclear particles that normally have only a fleeting existence following high-energy collisions. By combining Chandra and Hubble Space Telescope data, astronomers found that RX J1856 radiates like a solid body with a temperature of 1.2 million degrees Fahrenheit (700,000 degrees Celsius) and has a diameter of about seven miles (11.3 kilometers). This size is too small to reconcile with standard models for neutron stars -- until now the most extreme form of matter known. "Taken at face value, the combined observational evidence points to a star composed not of neutrons, but of quarks in a form known as strange quark matter," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and lead author of a paper on RX J1856 to appear in the June 20, 2002, issue of The Astrophysical Journal. "Quarks, thought to be the fundamental constituents of nuclear particles, have never been seen outside a nucleus in Earth-bound laboratories." Observations by Chandra of 3C58 also yielded startling results. A team composed of Patrick Slane and Steven Murray, also of CfA, and David Helfand of Columbia University, New York, failed to detect the expected X-radiation from the hot surface of 3C58, a neutron star believed to have been created in an explosion witnessed by Chinese and Japanese astronomers in A.D. 1181. The team concluded that the star has a temperature of less than one million degrees Celsius, which is far below the predicted

  10. Cosmic Ray-Dominated AGN Jets and the Formation of X-ray Cavities in Galaxy Clusters

    CERN Document Server

    Guo, Fulai

    2010-01-01

    It is widely accepted that feedback from active galactic nuclei (AGN) plays a key role in the evolution of gas in groups and clusters of galaxies. Unequivocal evidence comes from quasi-spherical X-ray cavities observed near cluster centers having sizes ranging from a few to tens of kpc, some containing non-thermal radio emission. Cavities apparently evolve from the interaction of AGN jets with the intracluster medium (ICM). However, in numerical simulations it has been difficult to create such fat cavities from narrow jets. Ultra-hot thermal jets dominated by kinetic energy typically penetrate deep into the ICM, forming radially elongated cavities at large radii unlike those observed. Here, we investigate the evolution of low-density jets dominated by relativistic cosmic rays (CRs) on kpc scales. We find that, when the thermal gas density in a CR-dominated jet is sufficiently low, the jet has a correspondingly low inertia, and thus decelerates quickly in the ICM. Furthermore, CR pressure causes the jet to exp...

  11. International X-ray Observatory (IXO) Assessment Study Report for the ESA Cosmic Vision 2015-2025

    CERN Document Server

    Barcons, X; Bautz, M; Bookbinder, J; Bregman, J; Dotani, T; Flanagan, K; Fraga-Encinas, R; Grady, J; Kunieda, H; Lumb, D H; Mitsuda, K; Nandra, K; Ohashi, T; Piro, L; Rando, N; Strüder, L; Takahashi, T; Tsuru, T G; White, N E

    2011-01-01

    The International X-Ray Observatory (IXO) will address fundamental questions in astrophysics, including "When did the first SMBH form? How does large scale structure evolve? What happens close to a black hole? What is the connection between these processes? What is the equation of state of matter at supra-nuclear density?" This report presents an overview of the assessment study phase of the IXO candidate ESA L-class Cosmic Vision mission. We provide a description of the IXO science objectives, the mission implementation and the payload. The performance will offer more than an order of magnitude improvement in capability compared with Chandra and XMM-Newton. This observatory-class facility comprises a telescope with highly nested grazing incidence optics with a performance requirement of 2.5 sq.m. of effective area at 1.25 keV with a 5" PSF. There is an instrument complement that provides capabilities in imaging, spatially resolved spectroscopy, timing, polarimetry and high resolution dispersive spectroscopy....

  12. Anomalies of the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Hansen, Martin Anders Kirstejn

    The Cosmic Microwave Background (CMB) is the faint afterglow of the extreme conditions that existed shortly after Big Bang. The temperature of the CMB radiation across the sky is extremely uniform, yet tiny anisotropies are present, and have with recent satellite missions been mapped to very high...

  13. Lowering the background level and the energy threshold of Micromegas x-ray detectors for axion searches

    CERN Document Server

    Iguaz, F J; Aznar, F; Castel, J F; Dafni, T; Davenport, M; Ferrer-Ribas, E; Galan, J; Garcia, J A; Garza, J G; Giomataris, I; Irastorza, I G; Papaevangelou, T; Rodriguez, A; Tomas, A; Vafeiadis, T; Yildiz, S C

    2014-01-01

    Axion helioscopes search for solar axions by their conversion in x-rays in the presence of high magnetic fields. The use of low background x-ray detectors is an essential component contributing to the sensitivity of these searches. In this work, we review the recent advances on Micromegas detectors used in the CERN Axion Solar Telescope (CAST) and proposed for the future International Axion Observatory (IAXO). The actual setup in CAST has achieved background levels below 10$^{-6}$ keV$^{-1}$ cm$^{-2}$ s$^{-1}$, a factor 100 lower than the first generation of Micromegas detectors. This reduction is based on active and passive shielding techniques, the selection of radiopure materials, offline discrimination techniques and the high granularity of the readout. We describe in detail the background model of the detector, based on its operation at CAST site and at the Canfranc Underground Laboratory (LSC), as well as on Geant4 simulations. The best levels currently achieved at LSC are low than 10$^{-7}$ keV$^{-1}$ ...

  14. pn-CCDs in a Low-Background Environment: Detector Background of the CAST X-ray Telescope

    CERN Document Server

    Kuster, M.; Rodriquez, A.; Kotthaus, R.; Brauninger, H.; Franz, J.; Friedrich, P.; Hartmann, R.; Kang, D.; Lutz, G.; Struder, L.

    2005-01-01

    The CAST experiment at CERN (European Organization of Nuclear Research) searches for axions from the sun. The axion is a pseudoscalar particle that was motivated by theory thirty years ago, with the intention to solve the strong CP problem. Together with the neutralino, the axion is one of the most promising dark matter candidates. The CAST experiment has been taking data during the last two years, setting an upper limit on the coupling of axions to photons more restrictive than from any other solar axion search in the mass range below 0.1 eV. In 2005 CAST will enter a new experimental phase extending the sensitivity of the experiment to higher axion masses. The CAST experiment strongly profits from technology developed for high energy physics and for X-ray astronomy: A superconducting prototype LHC magnet is used to convert potential axions to detectable X-rays in the 1-10 keV range via the inverse Primakoff effect. The most sensitive detector system of CAST is a spin-off from space technology, a Wolter I ty...

  15. X-Ray Synchrotron Emission from 10-100 TeV Cosmic-Ray Electrons in the Supernova Remnant SN 1006

    Science.gov (United States)

    Allen, G. E.; Petre, R.; Gotthelf, E. V.

    2001-09-01

    We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band from 0.12 to 17 keV. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kTe=0.6 keV, an ionization timescale n0t=9×109 cm-3 s, and a relative elemental abundance of silicon that is 10-18 times larger than the solar abundance. The nonthermal X-ray spectrum is described by a broken power law model with low- and high-energy photon indices Γ1=2.1 and Γ2=3.0, respectively. Since the nonthermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate previous claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larger than previous estimates of about 10 μG and arbitrarily use a value of 40 μG to estimate the parameters of the cosmic-ray electron, proton, and helium spectra of the remnant. The results for the ratio of the number densities of protons and electrons (R=160 at 1 GeV), the total energy in cosmic rays (Ecr=1×1050 ergs), and the spectral index of the electrons at 1 GeV (Γe=2.14+/-0.12) are consistent with the hypothesis that Galactic cosmic rays are accelerated predominantly in the shocks of supernova remnants. Yet, the remnant may or may not accelerate nuclei to energies as high as the energy of the ``knee,'' depending on the reason why the maximum energy of the electrons is only 10 TeV.

  16. Neutrino refraction by the cosmic neutrino background

    CERN Document Server

    Diaz, J S

    2015-01-01

    We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.

  17. Low-background X-ray detection with Micromegas for axion research

    CERN Document Server

    Garcia, J A; Diago, A; Ferrer-Ribas, E; Galán, J; Gardikiotis, A; Giomataris, I; Garza, J G; Iguaz, F J; Irastorza, I G; Ortega, I; Papaevangelou, T; Rodríguez, A; Tomás, A; Vafeiadis, T; Yildiz, S C

    2013-01-01

    We have studied low-background techniques in order to improve the background level for Micromegas detectors. These detectors are good candidates for rare event searches thanks to the low mass and the radiopurity of the materials used in the construction; moreover they have good discrimination capabilities. The motivation of these studies is the reduction of the background level in the CAST experiment where three of the four detectors operating currently are Micromegas of the microbulk type. The last result of the experience acquired in low-background techniques has been the reduction of the background level by a factor 4.5 for two detectors in the CAST experiment, corresponding to an improvement of a factor 2 in signal strength.

  18. Low-background X-ray detection with Micromegas for axion research

    Science.gov (United States)

    García, J. A.; Dafni, T.; Diago, A.; Ferrer-Ribas, E.; Galán, J.; Gardikiotis, A.; Giomataris, I.; Garza, J. G.; Iguaz, F. J.; Irastorza, I. G.; Ortega, I.; Papaevangelou, T.; Rodríguez, A.; Tomás, A.; Vafeiadis, T.; Yildiz, S. C.

    2013-10-01

    We have studied low-background techniques in order to improve the background level for Micromegas detectors. These detectors are good candidates for rare event searches thanks to the low mass and the radiopurity of the materials used in the construction; moreover they have good discrimination capabilities. The motivation of these studies is the reduction of the background level in the CAST experiment where three of the four detectors operating currently are Micromegas of the microbulk type. The last result of the experience acquired in low-background techniques has been the reduction of the background level by a factor 4.5 for two detectors in the CAST experiment, corresponding to an improvement of a factor 2 in signal strength.

  19. A Detector for Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    Wollack, E.; Cao, N.; Chuss, D.; Hsieh, W.-T.; Moseley, S. Harvey; Stevenson, T.; U-yen, K.

    2008-01-01

    We present preliminary design and development work on polarized detectors intended to enable Cosmic Microwave Background polarization measurements that will probe the first moments of the universe. The ultimate measurement will be challenging, requiring background-limited detectors and good control of systematic errors. Toward this end, we are integrating the beam control of HE-11 feedhorns with the sensitivity of transition-edge sensors. The coupling between these two devices is achieved via waveguide probe antennas and superconducting microstrip lines. This implementation allows band-pass filters to be incorporated on the detector chip. We believe that a large collection of single-mode polarized detectors will eventually be required for the reliable detection of the weak polarized signature that is expected to result from gravitational waves produced by cosmic inflation. This focal plane prototype is an important step along the path to this detection, resulting in a capability that will enable various future high performance instrument concepts.

  20. Gravitational Lensing of Cosmic Microwave Background Polarization

    CERN Document Server

    Ade, P A R; Anthony, A E; Arnold, K; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Jeune, M Le; Lee, A T; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Schanning, I; Schenck, D E; Sherwin, B; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2013-01-01

    Primary fluctuations in both temperature and polarization of the Cosmic Microwave Background (CMB) reflect the properties of the Universe from the Big Bang until the photons decoupled from matter 380,000 years later. These primary fluctuations are then lensed by large-scale structures (such as clusters of galaxies and filaments of dark matter), with the result that the distribution and properties of dark matter, including the masses of neutrinos, can be determined more accurately by extracting the lensing information than through studying the primary fluctuations alone. Polarization lensing can give cleaner, higher resolution results than temperature lensing. The correlation of lensed CMB polarization with large-scale structure, traced through the Cosmic Infrared Background, was recently detected; however, this correlation does not trace all structure and depends on the relationship between the infrared flux from the galaxies and the underlying mass distribution. Here we report the detection of gravitational ...

  1. Nonparametric Inference for the Cosmic Microwave Background

    CERN Document Server

    Genovese, C R; Nichol, R C; Arjunwadkar, M; Wasserman, L; Genovese, Christopher R.; Miller, Christopher J.; Nichol, Robert C.; Arjunwadkar, Mihir; Wasserman, Larry

    2004-01-01

    The Cosmic Microwave Background (CMB), which permeates the entire Universe, is the radiation left over from just 380,000 years after the Big Bang. On very large scales, the CMB radiation field is smooth and isotropic, but the existence of structure in the Universe - stars, galaxies, clusters of galaxies - suggests that the field should fluctuate on smaller scales. Recent observations, from the Cosmic Microwave Background Explorer to the Wilkinson Microwave Anisotropy Project, have strikingly confirmed this prediction. CMB fluctuations provide clues to the Universe's structure and composition shortly after the Big Bang that are critical for testing cosmological models. For example, CMB data can be used to determine what portion of the Universe is composed of ordinary matter versus the mysterious dark matter and dark energy. To this end, cosmologists usually summarize the fluctuations by the power spectrum, which gives the variance as a function of angular frequency. The spectrum's shape, and in particular the ...

  2. A Detector for Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    Wollack, E.; Cao, N.; Chuss, D.; Hsieh, W.-T.; Moseley, S. Harvey; Stevenson, T.; U-yen, K.

    2008-01-01

    We present preliminary design and development work on polarized detectors intended to enable Cosmic Microwave Background polarization measurements that will probe the first moments of the universe. The ultimate measurement will be challenging, requiring background-limited detectors and good control of systematic errors. Toward this end, we are integrating the beam control of HE-11 feedhorns with the sensitivity of transition-edge sensors. The coupling between these two devices is achieved via waveguide probe antennas and superconducting microstrip lines. This implementation allows band-pass filters to be incorporated on the detector chip. We believe that a large collection of single-mode polarized detectors will eventually be required for the reliable detection of the weak polarized signature that is expected to result from gravitational waves produced by cosmic inflation. This focal plane prototype is an important step along the path to this detection, resulting in a capability that will enable various future high performance instrument concepts.

  3. The impact of the in-orbit background and the X-ray source intensity on the centroiding accuracy of the Swift X-ray telescope

    CERN Document Server

    Ambrosi, R M; Hill, J; Cheruvu, C; Abbey, A F; Short, A D T

    2002-01-01

    The optical components of the Swift Gamma Ray Burst Explorer X-ray Telescope (XRT), consisting of the JET-X spare flight mirror and a charge coupled device of the type used in the EPIC program, were used in a re-calibration study carried out at the Panter facility, which is part of the Max Planck Institute for Extraterrestrial Physics. The objective of this study was to check the focal length and the off axis performance of the mirrors and to show that the half energy width (HEW) of the on-axis point spread function (PSF) was of the order of 16 arcsec at 1.5 keV (Nucl. Instr. and Meth. A 488 (2002) 543; SPIE 4140 (2000) 64) and that a centroiding accuracy better that 1 arcsec could be achieved within the 4 arcmin sampling area designated by the Burst Alert Telescope (Nucl. Instr. and Meth. A 488 (2002) 543). The centroiding accuracy of the Swift XRT's optical components was tested as a function of distance from the focus and off axis position of the PSF (Nucl. Instr. and Meth. A 488 (2002) 543). The presence ...

  4. Anomalies of the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Hansen, Martin Anders Kirstejn

    the model itself and the derived cosmological parameters, upon which most of the current astronomy and cosmology rests. In order to ascertain whether the anomalies are the results of systematics from the instruments, incomplete data treatment, residuals from foregrounds affecting the measurement of the true......The Cosmic Microwave Background (CMB) is the faint afterglow of the extreme conditions that existed shortly after Big Bang. The temperature of the CMB radiation across the sky is extremely uniform, yet tiny anisotropies are present, and have with recent satellite missions been mapped to very high...... accuracy. The information which the CMB provides has helped in creating the current standard cosmological model - the CDM model - and the theory of cosmic inflation as well as constrain a vast amount of cosmological parameters. The accuracy of observations of the CMB radiation is thus of extreme importance...

  5. Sunyaev-Zeldovich and Cosmic Microwave Background

    CERN Document Server

    Burigana, Carlo

    2007-01-01

    Since its original formulation the Sunyaev-Zeldovich (SZ) effect has been recognized as a ``powerful laboratory'' for our comprehension of physical processes in cosmic structures and to derive crucial information on some general properties of the universe. After a discussion of the fundamental concepts and of some well established applications of the SZ effect towards galaxy clusters, I will focus on dedicated themes related to the SZ effect and other features in the cosmic microwave background (CMB) of particular interest in the view of the extremely high angular resolution observations achievable in the future with the Square Kilometre Array (SKA). SKA will allow the mapping of the thermal and density structure of clusters of galaxies at radio and centimetre bands with unprecedented resolution and sensitivity and with an extremely accurate control of extragalactic radio source contamination. The signatures from SZ effects and free-free emission at galactic scales and in the intergalactic medium probe the st...

  6. XMM-Newton Observations of the Diffuse X-Ray Background

    Science.gov (United States)

    Galeazzi, M.; Gupta, A.; Covey, K.; Ursino, E.

    2007-04-01

    We analyze two XMM-Newton observations toward the high-density, high-latitude, neutral hydrogen cloud MBM 20 and a nearby low-density region that we call the Eridanus hole. MBM 20 lies at a distance between 100 and 200 pc from the Sun, and its density is sufficient to shield about 75% of the foreground emission in the 3/4 keV energy band. The combination of the two observations makes it possible to separate the foreground component, due to the Local Bubble and, possibly, charge exchange within the solar system, from the background component, due primarily to the Galactic halo and unidentified point sources. The two observations are in good agreement with each other and with ROSAT observations of the same part of the sky; the O VII and O VIII intensities are 3.89+/-0.56 and 0.68+/-0.24 photons cm-2 s-1 sr-1 for MBM 20, respectively, and 7.26+/-0.34 and 1.63+/-0.17 photons cm-2 s-1 sr-1 for the Eridanus hole. The spectra agree with a simple three-component model: one unabsorbed and one absorbed plasma component, and a power law, due to unresolved distant point sources. Assuming that the two plasma components are in thermal equilibrium, we obtain a temperature of 0.096 keV for the foreground component and 0.197 keV for the background one. Assuming the foreground component is due solely to Local Bubble emission, we obtain lower and upper limits for the plasma density of 0.0079 and 0.0095 cm-3 and limits of 16,200 and 19,500 cm-3 K for the plasma pressure, in good agreement with theoretical predictions. Similarly, assuming that the absorbed plasma component is due to Galactic halo emission, we obtain a plasma density ranging from 0.0009 to 0.0016 cm-3 and a pressure between 3.8×103 and 6.7×103 cm-3 K.

  7. Cross correlations of the cosmic infrared background

    CERN Document Server

    Zhang, P

    2003-01-01

    Cosmic infrared background (CIB) is a sensitive measure of the structure formation of the universe, especially the star formation history. But this background is overwhelmed by foregrounds. The cross correlation of CIB with galaxies is able to eliminate such foregrounds, minimize and localize several backgrounds which could bias the study of the star formation history. The cross correlation study of CIB has three advantages. (1) Combining the galaxy photometric redshift information, it directly measures the structure formation history. (2) The sky area used for CIB analysis is no long limited to the relatively clean sky. The utilization of CIB full sky data minimizes the sample variance. (3) The CIB measurement is no longer limited to several narrow frequency windows. This allows the measurement of CIB based on integrated intensity, whose theoretical prediction is based on energy conservation, thus is fairly model independent and robust. The cross correlation can be measured with 10% accuracy (statistical and...

  8. Cosmic Neutrino Background as a Ferromagnet

    CERN Document Server

    Arias, Paola; Lopez-Sarrion, Justo

    2013-01-01

    If cosmic background neutrinos interact very weakly with each other, through spin-spin interactions, then they may have experienced a phase transition, leading to a ferromagnetic ordering. The small magnetic field resulting from ferromagnetic ordering -- if present before galaxy formation -- could act as a primordial seed of the magnetic fields observed in several galaxies. Our findings suggest that the magnetization could occur in the right epoch, if the exchange gauge boson of neutrino-neutrino interaction is a massless boson beyond the Standard Model, with a coupling constant of $2.2\\times 10^{-13} \\left(\\frac{m_\

  9. Superhorizon Perturbations and the Cosmic Microwave Background

    CERN Document Server

    Erickcek, Adrienne L; Kamionkowski, Marc

    2008-01-01

    Superhorizon perturbations induce large-scale temperature anisotropies in the cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We analyze the CMB temperature anisotropies generated by a single-mode adiabatic superhorizon perturbation. We show that an adiabatic superhorizon perturbation in a LCDM universe does not generate a CMB temperature dipole, and we derive constraints to the amplitude and wavelength of a superhorizon potential perturbation from measurements of the CMB quadrupole and octupole. We also consider constraints to a superhorizon fluctuation in the curvaton field, which was recently proposed as a source of the hemispherical power asymmetry in the CMB.

  10. Chandra and XMM-Newton observations of the first quasars X-rays from the age of cosmic enlightenment

    CERN Document Server

    Vignali, C; Schneider, D P; Anderson, S F; Fan, X; Gunn, J E; Kaspi, S; Richards, G T; Strauss, M A; Strauss, Michael A.

    2003-01-01

    We report on Chandra and XMM-Newton observations of a sample of 13 quasars at z~4.7-5.4 mostly taken from the Sloan Digital Sky Survey (SDSS). The present sample complements previous X-ray studies of z>4 quasars, in which the majority of the objects are optically more luminous and at lower redshifts. All but two of our quasars have been detected in the X-ray band, thus doubling the number of z>4.8 X-ray detected quasars. The two non-detections are likely to be due to a short exposure time and to the presence of intrinsic absorption. We confirm and extend to the highest redshifts the presence of a correlation between AB1450(1+z) magnitude and soft X-ray flux for z>4 quasars, and the presence of a steeper optical-to-X-ray spectral energy distribution (parameterized by aox) for high-luminosity, high-redshift quasars than for lower-luminosity, lower-redshift quasars. The second effect is likely due to the known anti-correlation between aox and rest-frame 2500 Angstrom luminosity, whose significance is confirmed v...

  11. Optics Developments for X-Ray Astronomy

    Science.gov (United States)

    Ramsey, Brian

    2014-01-01

    X-ray optics has revolutionized x-ray astronomy. The degree of background suppression that these afford, have led to a tremendous increase in sensitivity. The current Chandra observatory has the same collecting area (approx. 10(exp 3)sq cm) as the non-imaging UHURU observatory, the first x-ray observatory which launched in 1970, but has 5 orders of magnitude more sensitivity due to its focusing optics. In addition, its 0.5 arcsec angular resolution has revealed a wealth of structure in many cosmic x-ray sources. The Chandra observatory achieved its resolution by using relatively thick pieces of Zerodur glass, which were meticulously figured and polished to form the four-shell nested array. The resulting optical assembly weighed around 1600 kg, and cost approximately $0.5B. The challenge for future x-ray astronomy missions is to greatly increase the collecting area (by one or more orders of magnitude) while maintaining high angular resolution, and all within realistic mass and budget constraints. A review of the current status of US optics for x-ray astronomy will be provided along with the challenges for future developments.

  12. Comptonization of cosmic microwave background photons in dwarf spheroidal galaxies

    Science.gov (United States)

    Culverhouse, Thomas L.; Evans, N. Wyn; Colafrancesco, S.

    2006-05-01

    We present theoretical modelling of the electron distribution produced by annihilating neutralino dark matter in dwarf spheroidal galaxies (dSphs). In particular, we follow up the idea of Colafrancesco and find that such electrons distort the cosmic microwave background (CMB) by the Sunyaev-Zeldovich (SZ) effect. For an assumed neutralino mass of 10 GeV and beam size of 1 arcsec, the SZ temperature decrement is of the order of nano-Kelvin for dSph models with a soft core. By contrast, it is of the order of micro-Kelvin for the strongly cusped dSph models favoured by some cosmological simulations. Although this is out of reach of current instruments, it may well be detectable by future mm telescopes, such as the Atacama Large Millimetre Array. We also show that the upscattered CMB photons have energies within reach of upcoming X-ray observatories, but that the flux of such photons is too small to be detectable now. None the less, we conclude that searching for the dark matter induced SZ effect is a promising way of constraining the dark distribution in dSphs, especially if the particles are light.

  13. Comptonisation of Cosmic Microwave Background Photons in Dwarf Spheroidal Galaxies

    CERN Document Server

    Culverhouse, T L; Colafrancesco, S; Culverhouse, Thomas L.

    2006-01-01

    We present theoretical modelling of the electron distribution produced by annihilating neutralino dark matter in dwarf spheroidal galaxies (dSphs). In particular, we follow up the idea of Colafrancesco (2004) and find that such electrons distort the cosmic microwave background (CMB) by the Sunyaev-Zeldovich effect. For an assumed neutralino mass of 10 GeV and beam size of 1'', the SZ temperature decrement is of the order of nano-Kelvin for dSph models with a soft core. By contrast, it is of the order of micro-Kelvin for the strongly cusped dSph models favoured by some cosmological simulations. Although this is out of reach of current instruments, it may well be detectable by future mm telescopes, such as ALMA. We also show that the upscattered CMB photons have energies within reach of upcoming X-ray observatories, but that the flux of such photons is too small to be detectable soon. Nonetheless, we conclude that searching for the dark matter induced Sunyaev-Zeldovich effect is a promising way of constraining ...

  14. Bayesian Analysis of the Cosmic Microwave Background

    Science.gov (United States)

    Jewell, Jeffrey

    2007-01-01

    There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background! Experiments designed to map the microwave sky are returning a flood of data (time streams of instrument response as a beam is swept over the sky) at several different frequencies (from 30 to 900 GHz), all with different resolutions and noise properties. The resulting analysis challenge is to estimate, and quantify our uncertainty in, the spatial power spectrum of the cosmic microwave background given the complexities of "missing data", foreground emission, and complicated instrumental noise. Bayesian formulation of this problem allows consistent treatment of many complexities including complicated instrumental noise and foregrounds, and can be numerically implemented with Gibbs sampling. Gibbs sampling has now been validated as an efficient, statistically exact, and practically useful method for low-resolution (as demonstrated on WMAP 1 and 3 year temperature and polarization data). Continuing development for Planck - the goal is to exploit the unique capabilities of Gibbs sampling to directly propagate uncertainties in both foreground and instrument models to total uncertainty in cosmological parameters.

  15. Radiation exposure due to cosmic rays and solar X-ray photons at various atmospheric heights in aviation range over India

    Science.gov (United States)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Bhattacharya, Arnab

    2016-07-01

    In this presentation we present our work on the continuous monitoring of radiation exposure in terms of effective dose rates, due to galactic cosmic rays (GCR) and solar X-rays at various altitudes within aviation range over India. As India belongs to equatorial region, there is negligible contribution from solar energetic particles (SEP). The calculation of cosmic ray counts as well as the solar X-ray photons are performed on the basis of the observation of various Dignity series balloon experiments on cosmic ray and solar high energy radiation studies, conducted by ICSP and Monte Carlo simulations performed with GEANT4 detector simulation software. The information on solar activity level from Geostationary Operational Environmental Satellite system (GOES) are employed in the calculations. A program, which is done entirely in MATLAB is employed to update regularly in a website, where we show images of dose rate (μSv) distribution over India at four different heights within the aviation range (updating at an interval of 30 minutes) and the approximate dose rates thats should be experienced by a pilot in an entire flight time between pairs of stations distributed all over India.

  16. The Cosmic Microwave Background anisotropies: open problems

    CERN Document Server

    Martínez-González, E

    2005-01-01

    The standard inflationary model presents a simple scenario within which the homogeneity, isotropy and flatness of the universe appear as natural outcomes and, in addition, fluctuations in the energy density are originated during the inflationary phase. These seminal density fluctuations give rise to fluctuations in the temperature of the Cosmic Microwave Background (CMB) at the decoupling surface. Afterward, the CMB photons propagate almost freely, with slight gravitational interactions with the evolving gravitational field present in the large scale structure (LSS) of the matter distribution and a low scattering rate with free electrons after the universe becomes reionized. These secondary effects slightly change the shape of the intensity and polarization angular power spectra (APS) of the radiation. The APS contain very valuable information on the parameters characterizing the background model of the universe and those parametrising the power spectra of both matter density perturbations and gravitational w...

  17. X-ray lasers

    CERN Document Server

    Elton, Raymond C

    2012-01-01

    The first in its field, this book is both an introduction to x-ray lasers and a how-to guide for specialists. It provides new entrants and others interested in the field with a comprehensive overview and describes useful examples of analysis and experiments as background and guidance for researchers undertaking new laser designs. In one succinct volume, X-Ray Lasers collects the knowledge and experience gained in two decades of x-ray laser development and conveys the exciting challenges and possibilities still to come._Add on for longer version of blurb_M>The reader is first introduced

  18. Probes of Cosmic Star Formation History

    Indian Academy of Sciences (India)

    Pranab Ghosh

    2002-03-01

    I summarize X-ray diagnostic studies of cosmic star formation history in terms of evolutionary schemes for X-ray binary evolution in normal galaxies with evolving star formation. Deep X-ray imaging studies by Chandra and XMM-Newton are now beginning to constrain both the X-ray luminosity evolution of galaxies and the log – log diagnostics of the X-ray background. I discuss these in the above context, summarizing current understanding and future prospects.

  19. Distant X-ray Galaxies: Insights from the Local Population

    CERN Document Server

    Moran, E C

    2004-01-01

    A full understanding of the origin of the hard X-ray background requires a complete and accurate census of the distant galaxies that produce it. Unfortunately, distant X-ray galaxies tend to be very faint at all wavelengths, which hinders efforts to perform this census. This chapter discusses the insights that can be obtained through comparison of the distant population to local X-ray galaxies, whose properties are well characterized. Such comparisons will ultimately aid investigations into the cosmic evolution of supermassive black holes and their environments.

  20. Data analysis of cosmic microwave background experiments

    Science.gov (United States)

    Abroe, Matthew Edmund

    2004-12-01

    The cosmic microwave background (CMB) is a powerful tool for determining and constraining the fundamental properties of our universe. In this thesis we present various computational and statistical techniques used to analyze datasets from CMB experiments, and apply them to both simulated and actual datasets. The algorithms presented in this thesis perform a variety of tasks in relation to the goal of extracting scientific information from CMB data sets. The CMB anisotropy power spectrum is sensitive to numerous parameters that determine the evolutionary and large scale properties of our universe. Now that numerous experiments have mapped the CMB intensity fluctuations on overlapping regions of the sky it is important to ensure that the various experiments are indeed observing the same signal. We cross-correlate the cosmic microwave background temperature anisotropy maps from the WMAP, MAXIMA-I, and MAXIMA-II experiments. The results conclusively show that the three experiments not only display the same statistical properties of the CMB anisotropy, but also detect the same features wherever the observed sky areas overlap. We conclude that the contribution of systematic errors to these maps is negligible and that MAXIMA and WMAP have accurately mapped the cosmic microwave background anisotropy. Due to a quadrapole anisotropy at last scattering it is predicted that the CMB photons should be linearly polarized, and that the polarization intensity will be roughly an order of magnitude lower than the intensity fluctuations. Two computationally intensive methods for simulating the CMB polarization signal on the sky are presented. Now that CMB polarization experiments are currently producing data sets new algorithms for analyzing polarization time stream data must be developed and tested. We demonstrate how to generate simulations of a polarization experiment in the temporal domain and apply these simulations to the MAXIPOL case. We develop a maximum likelihood map making

  1. X-ray Polarization in Relativistic Jets

    CERN Document Server

    McNamara, Aimee L; Wu, Kinwah

    2009-01-01

    We investigate the polarization properties of Comptonized X-rays from relativistic jets in Active Galactic Nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disk; scattering of cosmic microwave background (CMB) photons; and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disk and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases the maximum linear polarization is approximately 20%. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations of approximately P = 10 - 20% when synchrotron emission is localized near the jet base, while ...

  2. Physics of the cosmic microwave background anisotropy

    CERN Document Server

    Bucher, Martin

    2015-01-01

    Observations of the cosmic microwave background (CMB), especially of its frequency spectrum and its anisotropies, both in temperature and in polarization, have played a key role in the development of modern cosmology and our understanding of the very early universe. We review the underlying physics of the CMB and how the primordial temperature and polarization anisotropies were imprinted. Possibilities for distinguishing competing cosmological models are emphasized. The current status of CMB experiments and experimental techniques with an emphasis toward future observations, particularly in polarization, is reviewed. The physics of foreground emissions, especially of polarized dust, is discussed in detail, since this area is likely to become crucial for measurements of the B modes of the CMB polarization at ever greater sensitivity.

  3. Systematic distortion in cosmic microwave background maps

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making procedure.To inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these maps.By analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)maps.The detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

  4. Nonlinear Effects in the Cosmic Microwave Background

    CERN Document Server

    Maartens, R

    2000-01-01

    Major advances in the observation and theory of cosmic microwave background anisotropies have opened up a new era in cosmology. This has encouraged the hope that the fundamental parameters of cosmology will be determined to high accuracy in the near future. However, this optimism should not obscure the ongoing need for theoretical developments that go beyond the highly successful but simplified standard model. Such developments include improvements in observational modelling (e.g. foregrounds, non-Gaussian features), extensions and alternatives to the simplest inflationary paradigm (e.g. non-adiabatic effects, defects), and investigation of nonlinear effects. In addition to well known nonlinear effects such as the Rees-Sciama and Ostriker-Vishniac effects, further nonlinear effects have recently been identified. These include a Rees-Sciama-type tensor effect, time-delay effects of scalar and tensor lensing, nonlinear Thomson scattering effects and a nonlinear shear effect. Some of the nonlinear effects and th...

  5. Cosmological Constraints from the Cosmic Microwave Background

    CERN Document Server

    Le Dour, M D M; Bartlett, J G; Blanchard, A

    2000-01-01

    Using an approximate likelihood method adapted to band-power estimates, we analyze the ensemble of first generation cosmic microwave background anisotropy experiments to deduce constraints over a six-dimensional parameter space describing Inflation-generated adiabatic, scalar fluctuations. The basic preferences of simple Inflation scenarios are consistent with the data set: flat geometries $(\\OmT \\equiv 1-\\Omk \\sim 1)$ and a scale-invariant primeval spectrum ($n\\sim 1$) are favored. Models with significant negative curvature ($\\OmT < 0.7$) are eliminated, while constraints on postive curvature are less stringent. Degeneracies among the parameters prevent independent determinations of the matter density $\\OmM$ and the cosmological constant $\\Lambda$, and the Hubble constant $\\Ho$ remains relatively unconstrained. We also find that the relative height of the first Doppler peak suggests a high baryon content ($\\Omb h^2$), almost independently of the other parameters; besides the overall qualitative advance ex...

  6. Cosmic Microwave Background Acoustic Peak Locations

    CERN Document Server

    Pan, Zhen; Mulroe, Brigid; Narimani, Ali

    2016-01-01

    The Planck collaboration has measured the temperature and polarization of the cosmic microwave background well enough to determine the locations of eight peaks in the temperature (TT) power spectrum, five peaks in the polarization (EE) power spectrum and twelve extrema in the cross (TE) power spectrum. The relative locations of these extrema give a striking, and beautiful, demonstration of what we expect from acoustic oscillations in the plasma; e.g., that EE peaks fall half way between TT peaks. We expect this because the temperature map is predominantly sourced by temperature variations in the last scattering surface, while the polarization map is predominantly sourced by gradients in the velocity field, and the harmonic oscillations have temperature and velocity 90 degrees out of phase. However, there are large differences in expectations for extrema locations from simple analytic models vs. numerical calculations. Here we quantitatively explore the origin of these differences in gravitational potential tr...

  7. Canny Algorithm, Cosmic Strings and the Cosmic Microwave Background

    Science.gov (United States)

    Danos, Rebecca J.; Brandenberger, Robert H.

    We describe a new code to search for signatures of cosmic strings in cosmic microwave anisotropy maps. The code implements the Canny algorithm, an edge detection algorithm designed to search for the lines of large gradients in maps. Such a gradient signature which is coherent in position-space is produced by cosmic strings via the Kaiser-Stebbins effect. We test the power of our new code to set limits on the tension of the cosmic strings by analyzing simulated data, with and without cosmic strings. We compare maps with a pure Gaussian scale-invariant power spectrum with maps which have a contribution of a distribution of cosmic strings obeying a scaling solution. The maps have angular scale and angular resolution comparable to what current and future ground-based small-scale cosmic microwave anisotropy experiments will achieve. We present tests of the codes, indicate the limits on the string tension which could be set with the current code, and describe various ways to refine the analysis. Our results indicate that when applied to the data of ongoing cosmic microwave experiments such as the South Pole Telescope project, the sensitivity of our method to the presence of cosmic strings will be more than an order of magnitude better than the limits from existing analyses.

  8. Robustness of cosmic neutrino background detection in the cosmic microwave background

    CERN Document Server

    Audren, Benjamin; Cuesta, Antonio J; Gontcho, Satya Gontcho A; Lesgourgues, Julien; Niro, Viviana; Pellejero-Ibanez, Marcos; Pérez-Ràfols, Ignasi; Poulin, Vivian; Tram, Thomas; Tramonte, Denis; Verde, Licia

    2015-01-01

    The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effectiv...

  9. Chandra and XMM-Newton Observations of the First Quasars: X-Rays from the Age of Cosmic Enlightenment

    Science.gov (United States)

    Vignali, C.; Brandt, W. N.; Schneider, D. P.; Anderson, S. F.; Fan, X.; Gunn, J. E.; Kaspi, S.; Richards, G. T.; Strauss, Michael A.

    2003-06-01

    We report on Chandra and XMM-Newton observations of a sample of 13 quasars at z~4.7-5.4 mostly taken from the Sloan Digital Sky Survey (SDSS). The present sample complements previous X-ray studies of z>=4 quasars, in which the majority of the objects are optically more luminous and at lower redshifts. All but two of our quasars have been detected in the X-ray band, thus doubling the number of z>=4.8 X-ray-detected quasars. The two nondetections are likely to be due to a short exposure time (SDSSp J033829.31+002156.3) and to the presence of intrinsic absorption (SDSSp J173744.87+582829.5). We confirm and extend to the highest redshifts the presence of a correlation between AB1450(1+z) magnitude and soft X-ray flux for z>=4 quasars and the presence of a steeper optical-to-X-ray spectral energy distribution (parameterized by αox) for high-luminosity, high-redshift quasars than for lower luminosity, lower redshift quasars. The second effect is likely due to the known anticorrelation between αox and rest-frame 2500 Å luminosity, whose significance is confirmed via partial correlation analysis. The joint ~2.5-36 keV rest-frame spectrum of the z>4.8 SDSS quasars observed thus far by Chandra is well parameterized by a power law with photon index Γ=1.84+0.31-0.30; this photon index is consistent with those of z~0-3 quasars and that obtained from joint spectral fitting of z~4.1-4.5 optically luminous Palomar Digital Sky Survey quasars. No evidence for widespread intrinsic X-ray absorption has been found (NH<~4.0×1022 cm-2 on average at 90% confidence). We also obtained Hobby-Eberly Telescope (HET) photometric observations for eight of our target quasars. None of these shows significant (greater than 30%) optical variability over the time interval of a few years (in the observed frame) between the SDSS and HET observations.

  10. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  11. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  12. Fluctuations In The Cosmic Infrared Background Using the Cosmic Infrared Background ExpeRiment (CIBER).

    Science.gov (United States)

    Smidt, Joseph; Arai, T.; Battle, J.; Bock, J. J.; Cooray, A.; Frazer, C.; Hristov, V.; Keating, B.; Kim, M.; Lee, D.; Mason, P.; Matsumoto, T.; Mitchell-Wynne, K.; Nam, U.; Renbarger, T.; Smith, A.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2012-01-01

    The clustering properties of faint unresolved sources may be probed by examining the anisotropies they create in the Cosmic Infrared Background (CIB). Using information from fluctuations in the CIB at different wavelengths allows us to disentangle how clustering relates to redshift. In this talk, preliminary measurements of clustering using data from the Cosmic Infrared Background ExpeRiment (CIBER), a rocket-borne experiment designed to detect the signatures of unresolved infrared galaxies during reionization, will be discussed. The CIBER payload contains four instruments including two wide field imagers designed to measure fluctuations in the near IR cosmic infrared background (CIB) at 1.0 and 1.6 microns on scales between 0.2 and 100 arcmin in both bands, where the clustering of high-redshift sources is expected to peak. CIBER observations may be combined with Akari/NEP and Spitzer/NDWFS near-infrared surveys to check systematic errors and to fully characterize the electromagnetic spectrum of CIB fluctuations.

  13. Studies on the Background of the Wide Field Imager aboard the IXO and ATHENA X-Ray Telescopes

    OpenAIRE

    Hauf, Steffen

    2012-01-01

    The planned International X-ray Observatory (IXO) was the designated successor to the extremely suc- cessful XMM Newton and Chandra X-ray observatories. Aiming to provide high sensitivity, high spatial, spectral and timing resolution observations in the 0.1 keV – 40 keV energy range, the mission would have greatly extended our knowledge of the universe. The international project was canceled due to the pullout of NASA in 2010. Subsequently, ESA pursued an European-only mission: A Telescope fo...

  14. Probing inflation with the cosmic microwave background

    Science.gov (United States)

    Braganca, Vinicius Miranda

    The existence of a quasi-deSitter expansion in the early universe, known as inflation, generates the seeds of large-scale structures and is one of the foundations of the standard cosmological model. The main observational predictions from inflation include the existence of a nearly scale-invariant primordial power spectrum that is imprinted on the cosmic microwave background (CMB), which has been corroborated with remarkable precision in recent years. In single-field slow-roll inflation, a field called the inflaton dominates the energy density of the universe and slowly rolls in an almost perfectly flat potential. In addition, the motion of the inflaton field is friction dominated, with its velocity being completely specified by its position in the field space. This basic scenario is known as the slow-roll approximation and its validity is controlled by the magnitude of the so-called slow-roll parameters. Generalizations of single-field slow-roll inflation provide a wealth of observational signatures in the CMB temperature power spectrum, CMB polarization spectrum, primordial non-Guassianity and in lensing reconstruction. This thesis provides a series of consistency checks between these observables that can distinguish slow-roll violations from alternative explanations.

  15. Statistics of cosmic microwave background polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kamionkowski, M. [Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027 (United States); Kosowsky, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)]|[Department of Physics, Lyman Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States); Stebbins, A. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)

    1997-06-01

    We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding in the appropriate tensor spherical harmonics. We provide expressions for the complete set of temperature and polarization multipole moments for scalar and tensor metric perturbations. Four sets of multipole moments completely describe isotropic temperature and polarization correlations; for scalar metric perturbations one set is identically zero, giving the possibility of a clean determination of the vector and tensor contributions. The variance with which the multipole moments can be measured in idealized experiments is evaluated, including the effects of detector noise, sky coverage, and beam width. Finally, we construct coordinate-independent polarization two-point correlation functions, express them in terms of the multipole moments, and derive small-angle limits. {copyright} {ital 1997} {ital The American Physical Society}

  16. Statistics of cosmic microwave background polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kamionkowski, Marc; Kosowsky, Arthur; Stebbins, Albert

    1996-11-01

    We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding in the appropriate tensor spherical harmonics. We provide expressions for the complete set of temperature and polarization multipole moments for scalar and tensor metric perturbations. Four sets of multipole moments completely describe isotropic temperature and polarization correlations; for scalar metric perturbations one set is identically zero, giving the possibility of a clean determination of the vector and tensor contributions. The variance with which the multipole moments can be measured in idealized experiments is evaluated, including the effects of detector noise, sky coverage, and beam width. Finally, we construct coordinate-independent polarization two-point correlation functions, express them in terms of the multipole moments, and derive small-angle limits.

  17. Probing Inflation via Cosmic Microwave Background Polarimetry

    Science.gov (United States)

    Chuss, David T.

    2008-01-01

    The Cosmic Microwave Background (CMB) has been a rich source of information about the early Universe. Detailed measurements of its spectrum and spatial distribution have helped solidify the Standard Model of Cosmology. However, many questions still remain. Standard Cosmology does not explain why the early Universe is geometrically flat, expanding, homogenous across the horizon, and riddled with a small anisotropy that provides the seed for structure formation. Inflation has been proposed as a mechanism that naturally solves these problems. In addition to solving these problems, inflation is expected to produce a spectrum of gravitational waves that will create a particular polarization pattern on the CMB. Detection of this polarized signal is a key test of inflation and will give a direct measurement of the energy scale at which inflation takes place. This polarized signature of inflation is expected to be -9 orders of magnitude below the 2.7 K monopole level of the CMB. This measurement will require good control of systematic errors, an array of many detectors having the requisite sensitivity, and a reliable method for removing polarized foregrounds, and nearly complete sky coverage. Ultimately, this measurement is likely to require a space mission. To this effect, technology and mission concept development are currently underway.

  18. Cosmic Microwave Background Temperature at Galaxy Clusters

    CERN Document Server

    Battistelli, E S; Lamagna, L; Melchiorri, F; Palladino, E; Savini, G; Cooray, A R; Melchiorri, A; Rephaeli, Y; Shimon, M

    2002-01-01

    We have deduced the cosmic microwave background (CMB) temperature in the Coma cluster (Abell 1656, z=0.0231), and in Abell 2163 (z=0.203) from spectral measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio and microwave frequencies. The resulting temperatures at these redshifts are T_{Coma} = 2.750^{+0.043}_{-0.032} K and T_{A2163} = 3.335^{+0.065}_{-0.066} K, respectively. These values are in good agreement with the basic relation T(z)=T_{0}(1+z), where T_{0} = (2.725 +/- 0.002) K as measured by the COBE/FIRAS experiment. Alternative scaling relations that are conjectured in non-standard cosmologies can be constrained by the data; for example, if T(z) = T_{0}(1+z)^{1-a} or T(z)=T_0[1+(1+d)z], then a=-0.07^{+0.12}_{-0.11} and d = 0.07 +/- 0.12. We briefly discuss future prospects for more precise SZ measurements of T(z) at higher redshifts.

  19. The Hard X-ray Imager (HXI) for the ASTRO-H Mission

    Science.gov (United States)

    Sato, Goro; Kokubun, Motohide; Nakazawa, Kazuhiro; Enoto, Teruaki; Fukazawa, Yasushi; Harayama, Atsushi; Hayashi, Katsuhiro; Kataoka, Jun; Katsuta, Junichiro; Kawaharada, Madoka; Laurent, Philippe; Lebrun, François; Limousin, Olivier; Makishima, Kazuo; Mizuno, Tsunefumi; Mori, Kunishiro; Nakamori, Takeshi; Noda, Hirofumi; Odaka, Hirokazu; Ohno, Masanori; Ohta, Masayuki; Saito, Shinya; Sato, Rie; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shinichiro; Terada, Yukikatsu; Uchiyama, Hideki; Uchiyama, Yasunobu; Watanabe, Shin; Yamaoka, Kazutaka; Yatsu, Yoichi; Yuasa, Takayuki

    2014-07-01

    The 6th Japanese X-ray satellite, ASTRO-H, is scheduled for launch in 2015. The hard X-ray focusing imaging system will observe astronomical objects with the sensitivity for detecting point sources with a brightness of 1/100,000 times fainter than the Crab nebula at > 10 keV. The Hard X-ray Imager (HXI) is a focal plane detector 12 m below the hard X-ray telescope (HXT) covering the energy range from 5 to 80 keV. The HXI is composed of a stacked Si/CdTe semiconductor detector module and surrounding BGO scintillators. The latter work as active shields for efficient reduction of background events caused by cosmic-ray particles, cosmic X-ray background, and in-orbit radiation activation. In this paper, we describe the detector system, and present current status of flight model development, and performance of HXI using an engineering model of HXI.

  20. A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research

    CERN Document Server

    Aznar, F; Christensen, F E; Dafni, T; Decker, T A; Ferrer-Ribas, E; Garcia, J A; Giomataris, I; Gracia, J G; Hailey, C J; Hill, R M; Iguaz, F J; Irastorza, I G; Jakobsen, A C; Luzon, G; Mirallas, H; Papaevangelou, T; Pivovaroff, M J; Ruz, J; Vafeiadis, T; Vogel, J K

    2015-01-01

    We report on the design, construction and operation of a low background x-ray detection line composed of a shielded Micromegas (micromesh gaseous structure) detector of the microbulk technique. The detector is made from radiopure materials and is placed at the focal point of a $\\sim$~5 cm diameter, 1.3 m focal-length, cone-approximation Wolter I x-ray telescope (XRT) comprised of thermally-formed (or "slumped") glass substrates deposited with multilayer coatings. The system has been conceived as a technological pathfinder for the future International Axion Observatory (IAXO), as it combines two of the techniques (optic and detector) proposed in the conceptual design of the project. It is innovative for two reasons: it is the first time an x-ray optic has been designed and fabricated specifically for axion research, and the first time a Micromegas detector has been operated with an x-ray optic. The line has been installed at one end of the CERN Axion Solar Telescope (CAST) magnet and is currently looking for s...

  1. High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

    Science.gov (United States)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A; Zhang, Will

    2014-01-01

    We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  2. Electron Heating and Cosmic Rays at a Supernova Shock from Chandra X-ray Observations of E0102.2-7219

    CERN Document Server

    Hughes, J P; Decourchelle, A; Hughes, John P.; Rakowski, Cara E.; Decourchelle, Anne

    2000-01-01

    In this Letter we use the unprecedented spatial resolution of the Chandra X-ray Observatory to carry out, for the first time, a measurement of the post-shock electron temperature and proper motion of a young SNR, specifically to address questions about the post-shock partition of energy among electrons, ions, and cosmic rays. The expansion rate, 0.100 +/- 0.025 percent per yr, and inferred age, ~1000 yr, of E0102.2-7219, from a comparison of X-ray observations spanning 20 years, are fully consistent with previous estimates based on studies of high velocity oxygen-rich optical filaments in the remnant. With a radius of 6.4 pc for the blast wave estimated from the Chandra image, our expansion rate implies a blast wave velocity of ~6000 km/s and a range of electron temperatures 2.5 - 45 keV, dependent on the degree of collisionless electron heating. Analysis of the Chandra ACIS spectrum of the immediate post-shock region reveals a thermal plasma with abundances and column density typical of the Small Magellanic ...

  3. Spectral measurements of the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, A.J.

    1989-04-01

    Three experiments have measured the intensity of the Cosmic Microwave Background (CMB) at wavelengths 4.0, 3.0, and 0.21 cm. The measurement at 4.0 cm used a direct-gain total-power radiometer to measure the difference in power between the zenith sky and a large cryogenic reference target. Foreground signals are measured with the same instrument and subtracted from the zenith signal, leaving the CMB as the residual. The reference target consists of a large open-mouth cryostat with a microwave absorber submerged in liquid helium; thin windows block the radiative heat load and prevent condensation atmospheric gases within the cryostat. The thermodynamic temperature of the CMB at 4.0 cm is 2.59 +- 0.07 K. The measurement at 3.0 cm used a superheterodyne Dicke-switched radiometer with a similar reference target to measure the zenith sky temperature. A rotating mirror allowed one of the antenna beams to be redirected to a series of zenith angles, permitting automated atmospheric measurements without moving the radiometer. A weighted average of 5 years of data provided the thermodynamic temperature of the CMB at 3.0 cm of 2.62 +- 0.06 K. The measurement at 0.21 cm used Very Large Array observations of interstellar ortho-formaldehyde to determine the CMB intensity in molecular clouds toward the giant HII region W51A (G49.5-0.4). Solutions of the radiative transfer problem in the context of a large velocity gradient model provided estimates of the CMB temperature within the foreground clouds. Collisional excitation from neutral hydrogen molecules within the clouds limited the precision of the result. The thermodynamic temperature of the CMB at 0.21 cm is 3.2 +- 0.9 K. 72 refs., 27 figs., 38 tabs.

  4. On forbidden high-energy electrons as a source of background in X-ray and gamma-ray observations

    CERN Document Server

    Suvorova, Alla V

    2014-01-01

    The study is devoted to a problem of electron-induced contaminant to X-ray and gamma-ray astrophysical measurements on board low-orbiting satellites. We analyzed enhancements of electron fluxes in energy range 100 - 300 keV observed at equatorial and low latitudes by a fleet of NOAA/POES low-orbiting satellites over the time period from 2003 to 2005. It was found that 100-300 keV electron fluxes in the forbidden zone below the inner radiation belt enhanced by several orders of magnitude during geomagnetic storms and/or under strong compressions of the magnetosphere. The enhancements are related to high substorm activity and occurred at any local time. Intense fluxes of the energetic electrons in the forbidden zone can be considered as an essential contaminant to X-ray and gamma-ray measurements at low-latitude and low-altitude orbits.

  5. Probing Cosmic Distance Duality Relation with Sunyaev-Zeldovich Effect, X-rays Observations and Supernovae Ia

    CERN Document Server

    Holanda, R F L; Ribeiro, M B

    2011-01-01

    Measurements of Sunyaev-Zeldovich effect and X-ray combined with the validity of the distance-duality relation can determine the angular diameter distances from galaxy clusters. This sort of combination enable us to probe the galaxy cluster physics or even to test the validity of the distance-duality relation based on two different approaches. Firstly, the possible galaxy cluster morphologies are constrained by assuming the strict validity of the distance-duality relation in the LCDM framework. Secondly, by adopting a cosmological-model-independent test, we confront directly the angular diameters from galaxy clusters with two Supernovae Ia (SNe Ia) sub-samples (carefully chosen to coincide with cluster positions). In our analysis we consider three galaxy clusters samples whose difference lies in the underlying assumptions used to describe the clusters: (i) isothermal elliptical beta model, (ii) isothermal spherical beta model, and (iii) non-isothermal spherical double beta model. The elliptical beta model pro...

  6. Skull x-ray

    Science.gov (United States)

    X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  7. Neck x-ray

    Science.gov (United States)

    X-ray - neck; Cervical spine x-ray; Lateral neck x-ray ... There is low radiation exposure. X-rays are monitored so that the lowest amount of radiation is used to produce the image. Pregnant women and ...

  8. A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite

    Energy Technology Data Exchange (ETDEWEB)

    Mather, J.C.; Cheng, E.S.; Shafer, R.A.; Bennett, C.L.; Boggess, N.W.; Dwek, E.; Hauser, M.G.; Kelsall, T.; Moseley, S.H. Jr.; Silverberg, R.F. (NASA, Goddard Space Flight Center, Greenbelt, MD (USA))

    1990-05-01

    A preliminary spectrum is presented of the background radiation between 1 and 20/cm from regions near the north Galactic pole, as observed by the FIRAS instrument on the COBE satellite. The spectral resolution is 1/cm. The spectrum is well fitted by a blackbody with a temperature of 2.735 + or - 0.06 K, and the deviation from a blackbody is less than 1 percent of the peak intensity over the range 1-20/cm. These new data show no evidence for the submillimeter excess previously reported by Matsumoto et al. (1988) in the cosmic microwave background. Further analysis and additional data are expected to improve the sensitivity to deviations from a blackbody spectrum by an order of magnitude. 31 refs.

  9. A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite

    Science.gov (United States)

    Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Bennett, C. L.; Boggess, N. W.; Dwek, E.; Hauser, M. G.; Kelsall, T.; Moseley, S. H., Jr.; Silverberg, R. F.

    1990-01-01

    A preliminary spectrum is presented of the background radiation between 1 and 20/cm from regions near the north Galactic pole, as observed by the FIRAS instrument on the COBE satellite. The spectral resolution is 1/cm. The spectrum is well fitted by a blackbody with a temperature of 2.735 + or - 0.06 K, and the deviation from a blackbody is less than 1 percent of the peak intensity over the range 1-20/cm. These new data show no evidence for the submillimeter excess previously reported by Matsumoto et al. (1988) in the cosmic microwave background. Further analysis and additional data are expected to improve the sensitivity to deviations from a blackbody spectrum by an order of magnitude.

  10. A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite

    Science.gov (United States)

    Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Bennett, C. L.; Boggess, N. W.; Dwek, E.; Hauser, M. G.; Kelsall, T.; Moseley, S. H., Jr.; Silverberg, R. F.

    1990-01-01

    A preliminary spectrum is presented of the background radiation between 1 and 20/cm from regions near the north Galactic pole, as observed by the FIRAS instrument on the COBE satellite. The spectral resolution is 1/cm. The spectrum is well fitted by a blackbody with a temperature of 2.735 + or - 0.06 K, and the deviation from a blackbody is less than 1 percent of the peak intensity over the range 1-20/cm. These new data show no evidence for the submillimeter excess previously reported by Matsumoto et al. (1988) in the cosmic microwave background. Further analysis and additional data are expected to improve the sensitivity to deviations from a blackbody spectrum by an order of magnitude.

  11. Cosmic Connections:. from Cosmic Rays to Gamma Rays, Cosmic Backgrounds and Magnetic Fields

    Science.gov (United States)

    Kusenko, Alexander

    2013-12-01

    Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances, including a theory explaining the hard spectra of distant blazars and the measurements of intergalactic magnetic fields based on the spectra of distant sources. Furthermore, we discuss the possible contribution of transient galactic sources, such as past gamma-ray bursts and hypernova explosions in the Milky Way, to the observed ux of ultrahigh-energy cosmicrays nuclei. The need for a holistic treatment of gamma rays, cosmic rays, and magnetic fields serves as a unifying theme for these seemingly unrelated phenomena.

  12. Toward the standard population synthesis model of the X-ray background: Evolution of X-ray luminosity and absorption functions of active galactic nuclei including Compton-thick populations

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Yoshihiro [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Akiyama, Masayuki [Astronomical Institute, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Hasinger, Günther [Institute for Astronomy, 2680 Woodlawn Drive Honolulu, HI 96822-1839 (United States); Miyaji, Takamitsu [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, Baja California (Mexico); Watson, Michael G. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

    2014-05-10

    We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ∼ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ≈0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

  13. The Cosmic Web and galaxy evolution around the most luminous X-ray cluster: RXJ1347.5-1145

    CERN Document Server

    Verdugo, M; Boehringer, H; Hildebrandt, H; Ziegler, B L; Erben, T; Finoguenov, A; Chon, G

    2011-01-01

    In this paper we study the large scale structures and their galaxy content around the most X-ray luminous cluster known, RX J1347.5-1145 at z=0.45. We make use of ugriz CFHT MEGACAM photometry and VIMOS VLT spectroscopy to identify structures around the RXJ1347 on a scale of 20x20 Mpc2. We construct maps of the galaxy distribution and the fraction of blue galaxies. We study the photometric galaxy properties as a function of environment, traced by the galaxy density. We identify group candidates based on galaxy overdensities and study their galaxy content. We also use available GALEX NUV imaging to identify strong unobscured star forming galaxies. We find that the large scale structure around RXJ1347 extends in the NE-SW direction for at least 20 Mpc, in which most of the group candidates are located. As other studies, we find that the fraction of blue galaxies (Fblue) is a function of galaxy number density, but the bulk of the trend is due to galaxies belonging to massive systems. The fraction of the UV-brigh...

  14. Impact of supernova and cosmic-ray driving on the surface brightness of the galactic halo in soft X-rays

    CERN Document Server

    Peters, Thomas; Gatto, Andrea; Naab, Thorsten; Walch, Stefanie; Wünsch, Richard; Glover, Simon C O; Clark, Paul C; Klessen, Ralf S; Baczynski, Christian

    2015-01-01

    The halo of the Milky Way contains a hot plasma with a surface brightness in soft X-rays of the order $10^{-12}$erg cm$^{-2}$ s$^{-1}$ deg$^{-2}$. The origin of this gas is unclear, but so far numerical models of galactic star formation have failed to reproduce such a large surface brightness by several orders of magnitude. In this paper, we analyze simulations of the turbulent, magnetized, multi-phase interstellar medium including thermal feedback by supernova explosions as well as cosmic-ray feedback. We include a time-dependent chemical network, self-shielding by gas and dust, and self-gravity. Pure thermal feedback alone is sufficient to produce the observed surface brightness, although it is very sensitive to the supernova rate. Cosmic rays suppress this sensitivity and reduce the surface brightness because they drive cooler outflows. Self-gravity has by far the largest effect because it accumulates the diffuse gas in the disk in dense clumps and filaments, so that supernovae exploding in voids can eject...

  15. Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates

    Science.gov (United States)

    Ricotti, Massimo; Ostriker, Jeremiah P.; Mack, Katherine J.

    2008-06-01

    We investigate the effect of nonevaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the cosmic microwave background (CMB). Using the third-year WMAP data and COBE FIRAS data we improve existing upper limits on the abundance of PBHs with masses >0.1 M⊙ by several orders of magnitude. The new upper limits still allow PBHs to be important for the origin of supermassive black holes and ultraluminous X-ray sources. Fitting WMAP3 data with cosmological models that do not allow for nonstandard recombination histories, as produced by PBHs or other early energy sources, may lead to an underestimate of the best-fit values of the amplitude of linear density fluctuations (σ8) and the scalar spectral index (ns). Cosmological parameter estimates are affected because models with PBHs allow for larger values of the Thomson scattering optical depth, whose correlation with other parameters may not be correctly taken into account when PBHs are ignored. Values of τe ~ 0.2, ns ~ 1, and σ8 ~ 0.9 are allowed at 95% CF. This result may relieve recent tension between WMAP3 data and clusters data on the value of σ8. PBHs may increase the primordial molecular hydrogen abundance by up to 2 orders of magnitude, this promoting cooling and star formation. The suppression of galaxy formation due to X-ray heating is negligible for models consistent with the CMB data. Thus, the formation rate of the first galaxies and stars would be enhanced by a population of PBHs.

  16. X-Ray Binary Populations in a Cosmological Context, Including NuSTAR Predictions

    Science.gov (United States)

    Cardiff, Ann Hornschemeier

    2011-01-01

    The new ultradeep 4 Ms Chandra Deep Field South has afforded the deepest view ever of X-ray binary populations. We report on the latest results on both LMXB and HMXB evolution out to redshifts of approximately four, including comparison with the latest theoretical models, using this deepest-ever view of the X-ray universe with Chandra. The upcoming NuSTAR mission will open up X-ray binary populations in the hard X-ray band, similar to the pioneering work of Fabbiano et al. in the Einstein era. We report on plans to study both Local Group and starburst galaxies as well as the implications those observations may have for X-ray binary populations in galaxies contributing to the Cosmic X-ray Background.

  17. Detection of X-ray Emission from the Eastern Radio Lobe of PICTOR A

    CERN Document Server

    Grandi, P; Maraschi, L; Morganti, R; Fusco-Femiano, R; Fiocchi, M; Ballo, L; Tavecchio, F; Grandi, Paola; Guainazzi, Matteo; Maraschi, Laura; Morganti, Raffaella; Fusco-Femiano, Roberto; Fiocchi, Mariateresa; Ballo, Lucia; Tavecchio, Fabrizio

    2003-01-01

    The XMM-Newton satellite has revealed extended X-ray emission from the eastern radio lobe of the Fanaroff-Riley II Radio Galaxy Pictor A. The X-ray spectrum, accumulated on a region covering about half the entire radio lobe, is well described by both a thermal model and a power law. The X-ray emission could be thermal and produced by circum-galactic gas shocked by the expanding radio lobe or, alternatively, by Inverse Compton (IC) of cosmic microwave background photons by relativistic electrons in the lobe. The latter possibility seems to be supported by the good agreement between the lobe-average synchrotron radio index and the X-ray energy slope. However, if this is the case, the magnetic field, as deduced from the comparison of the IC X-ray and radio fluxes, is more than a factor 2 below the equipartition value estimated in the same X-ray region.

  18. X-Ray Visions of SS Cygni

    Science.gov (United States)

    Young, D. L.

    2004-12-01

    The Chandra X-Ray Observatory is the most sophisticated X-ray observatory launched by NASA. Chandra is designed to observe X-rays from highenergy regions of the universe, such as X-ray binary stars. On September 14, 2000, triggered by alerts from amateur astronomers worldwide, Chandra observed the outburst of the brightest northern dwarf nova SS Cygni. The cooperation of hundreds of amateur variable star astronomers and the Chandra X-Ray scientists and spacecraft specialists provided proof that the collaboration of amateur and professional astronomers is a powerful tool to study cosmic phenomena.

  19. Lorentz-violating electrodynamics and the cosmic microwave background.

    Science.gov (United States)

    Kostelecký, V Alan; Mewes, Matthew

    2007-07-06

    Possible Lorentz-violating effects in the cosmic microwave background are studied. We provide a systematic classification of renormalizable and nonrenormalizable operators for Lorentz violation in electrodynamics and use polarimetric observations to search for the associated violations.

  20. Spider casts its web on the cosmic microwave background

    Science.gov (United States)

    Banks, Michael

    2015-02-01

    An experiment successfully touched down in Antarctica last month after gathering data on the cosmic microwave background (CMB) that could reveal the faint remnants of gravitational waves created during that rapid expansion of the very early universe known as inflation.

  1. Using the cosmic microwave background to discriminate among inflation models

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, W.H.

    1997-12-23

    The upcoming satellite missions MAP and Planck will measure the spectrum of fluctuations in the Cosmic Microwave Background with unprecedented accuracy. I discuss the prospect of using these observations to distinguish among proposed models of inflationary cosmology.

  2. High-energy X-ray detection of G359.89–0.08 (SGR A–E): Magnetic flux tube emission powered by cosmic rays?

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuo; Hailey, Charles J.; Gotthelf, Eric V.; Mori, Kaya; Nynka, Melania [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Baganoff, Frederick K. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bauer, Franz E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile 306, Santiago 22 (Chile); Boggs, Steven E.; Craig, William W.; Tomsick, John A. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W., E-mail: shuo@astro.columbia.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-03-20

    We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89–0.08 (Sgr A–E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ∼50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index Γ ≈ 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F{sub X} = (2.0 ± 0.1) × 10{sup –12} erg cm{sup –2} s{sup –1}, corresponding to an unabsorbed X-ray luminosity L{sub X} = (2.6 ± 0.8) × 10{sup 34} erg s{sup –1} assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A–E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to ∼100 kyr) with low surface brightness and radii up to ∼30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

  3. A Search for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse Background

    CERN Document Server

    Sekiya, Norio; Mitsuda, Kazuhisa

    2015-01-01

    We performed the deepest search for an X-ray emission line between 0.5 and 7 keV from non-baryonic dark matter with the Suzaku XIS. Dark matter associated with the Milky Way galaxy was selected as the target to obtain the best signal-to-noise ratio. From the Suzaku archive, we selected 187 data sets of blank sky regions which were dominated by the X-ray diffuse background. The data sets were from 2005 to 2013. Instrumental responses were adjusted by multiple calibration data sets of the Crab Nebula. We also improved the technique of subtracting lines of instrumental origin. These energy spectra were well described by X-ray emission due to charge exchange around the Solar System, hot plasma in and around the Milky Way and superposition of extra-galactic point sources. A signal of a narrow emission line was searched for, and the significance of detection was evaluated in consideration of the blind search method (the Look-elsewhere Effect). Our results exhibited no significant detection of an emission line featu...

  4. A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research

    DEFF Research Database (Denmark)

    Aznar, F.; Castel, J.; Christensen, F. E.

    2015-01-01

    -approximation Wolter I x-ray telescope (XRT) assembled from thermally-formed (or "slumped") glass substrates deposited with multilayer coatings. The system has been conceived as a technological pathfinder for the future International Axion Observatory (IAXO), as it combines two of the techniques (optic and detector......) proposed in the conceptual design of the project. It is innovative for two reasons: it is the first time an x-ray optic has been designed and fabricated specifically for axion research, and the first time a Micromegas detector has been operated with an x-ray optic. The line has been installed at one end...... of the CERN Axion Solar Telescope (CAST) magnet and is currently looking for solar axions. The combination of the XRT and Micromegas detector provides the best signal-to-noise ratio obtained so far by any detection system of the CAST experiment with a background rate of 5.4×10−3 counts per hour in the energy...

  5. A sensitive search for unknown spectral emission lines in the diffuse X-ray background with XMM-Newton

    CERN Document Server

    Gewering-Peine, A; Schmitt, J H M M

    2016-01-01

    The Standard Model of particle physics can be extended to include sterile (right-handed) neutrinos or axions to solve the dark matter problem. Depending upon the mixing angle between active and sterile neutrinos, the latter have the possibility to decay into monoenergetic active neutrinos and photons in the keV-range while axions can couple to two photons. We have used data taken with X-ray telescopes like e.g. XMM-Newton for the search of line emissions. We used pointings with high exposures and expected dark matter column densities with respect to the dark matter halo of the Milky Way. The posterior predictive p-value analysis has been applied to locate parameter space regions which favour additional emission lines. In addition, upper limits of the parameter space of the models have been generated such that the preexisting limits have been significantly improved.

  6. The Effects of X-Ray and UV Background Radiation on the Low-Mass Slope of the Galaxy Mass Function

    CERN Document Server

    Hambrick, D C; Johansson, P H; Naab, T

    2010-01-01

    Even though the dark-matter power spectrum in the absence of biasing predicts a number density of halos n(M) ~ M^-2 (i.e. a Schechter alpha value of -2) at the low-mass end (M < 10^10 M_solar), hydrodynamic simulations have typically produced values for stellar systems in good agreement with the observed value alpha ~ -1. We explain this with a simple physical argument and show that an efficient external gas-heating mechanism (such as the UV background included in all hydro codes) will produce a critical halo mass below which halos cannot retain their gas and form stars. We test this conclusion with GADGET-2-based simulations using various UV backgrounds, and for the first time we also investigate the effect of an X-ray background. We show that at the present epoch alpha is depends primarily on the mean gas temperature at the star-formation epoch for low-mass systems (z <~ 3): with no background we find alpha ~ -1.5, with UV only alpha ~ -1.0, and with UV and X-rays alpha ~ -0.75. We find the critical f...

  7. Scientific results from the cosmic background explorer (COBE). [Information on cosmic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.L.; Boggess, N.W.; Cheng, E.S.; Hauser, M.G.; Kelsall, T.; Mather, J.C.; Moseley, S.H. Jr.; Shafer, R.A.; Silverberg, R.F. (NASA/Goddard Space Flight Center, Greenbelt, MD (United States)); Murdock, T.L. (General Research Corp., Danvers, MA (United States)); Smoot, G.F. (Lawrence Berkeley Lab., CA (United States)); Weiss, R. (Massachusetts Inst. of Technology, Cambridge (United States)); Wright, E.L. (Univ. of California, Los Angeles (United States))

    1993-06-01

    The National Aeronautics and Space Administration (NASA) has flown the COBE satellite to observe the Big Bang and the subsequent formation of galaxies and large-scale structure. Data from the Far-Infrared Absolute Spectrophotometer (FIRAS) show that the spectrum of the cosmic microwave background is that of a black body of temperature T = 2.73 [+-] 0.06 K, with no deviation from a black-body spectrum greater than 0.25% of the peak brightness. The data from the Differential Microwave Radiometers (DMR) show statistically significant cosmic microwave background anisotropy, consistent with a scale-invariant primordial density fluctuation spectrum. Measurements from the Diffuse Infrared Background Experiment (DIRBE) provide new conservation upper limits to the cosmic infrared background. Extensive modeling of solar system and galactic infrared foregrounds is required for further improvement in the cosmic infrared background limits. 104 refs., 1 tab.

  8. Impact of Supernova and Cosmic-Ray Driving on the Surface Brightness of the Galactic Halo in Soft X-Rays

    Science.gov (United States)

    Peters, Thomas; Girichidis, Philipp; Gatto, Andrea; Naab, Thorsten; Walch, Stefanie; Wünsch, Richard; Glover, Simon C. O.; Clark, Paul C.; Klessen, Ralf S.; Baczynski, Christian

    2015-11-01

    The halo of the Milky Way contains a hot plasma with a surface brightness in soft X-rays of the order 10-12 erg cm-2 s-1 deg-2. The origin of this gas is unclear, but so far numerical models of galactic star formation have failed to reproduce such a large surface brightness by several orders of magnitude. In this paper, we analyze simulations of the turbulent, magnetized, multi-phase interstellar medium including thermal feedback by supernova explosions as well as cosmic-ray feedback. We include a time-dependent chemical network, self-shielding by gas and dust, and self-gravity. Pure thermal feedback alone is sufficient to produce the observed surface brightness, although it is very sensitive to the supernova rate. Cosmic rays suppress this sensitivity and reduce the surface brightness because they drive cooler outflows. Self-gravity has by far the largest effect because it accumulates the diffuse gas in the disk in dense clumps and filaments, so that supernovae exploding in voids can eject a large amount of hot gas into the halo. This can boost the surface brightness by several orders of magnitude. Although our simulations do not reach a steady state, all simulations produce surface brightness values of the same order of magnitude as the observations, with the exact value depending sensitively on the simulation parameters. We conclude that star formation feedback alone is sufficient to explain the origin of the hot halo gas, but measurements of the surface brightness alone do not provide useful diagnostics for the study of galactic star formation.

  9. IMPACT OF SUPERNOVA AND COSMIC-RAY DRIVING ON THE SURFACE BRIGHTNESS OF THE GALACTIC HALO IN SOFT X-RAYS

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Thomas; Girichidis, Philipp; Gatto, Andrea; Naab, Thorsten [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Walch, Stefanie [Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany); Wünsch, Richard [Astronomical Institute, Academy of Sciences of the Czech Republic, Bocni II 1401, 141 31 Prague (Czech Republic); Glover, Simon C. O.; Klessen, Ralf S.; Baczynski, Christian [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Clark, Paul C., E-mail: tpeters@mpa-garching.mpg.de [School of Physics and Astronomy, Cardiff University, 5 The Parade, Cardiff CF24 3AA, Wales (United Kingdom)

    2015-11-10

    The halo of the Milky Way contains a hot plasma with a surface brightness in soft X-rays of the order 10{sup −12} erg cm{sup −2} s{sup −1} deg{sup −2}. The origin of this gas is unclear, but so far numerical models of galactic star formation have failed to reproduce such a large surface brightness by several orders of magnitude. In this paper, we analyze simulations of the turbulent, magnetized, multi-phase interstellar medium including thermal feedback by supernova explosions as well as cosmic-ray feedback. We include a time-dependent chemical network, self-shielding by gas and dust, and self-gravity. Pure thermal feedback alone is sufficient to produce the observed surface brightness, although it is very sensitive to the supernova rate. Cosmic rays suppress this sensitivity and reduce the surface brightness because they drive cooler outflows. Self-gravity has by far the largest effect because it accumulates the diffuse gas in the disk in dense clumps and filaments, so that supernovae exploding in voids can eject a large amount of hot gas into the halo. This can boost the surface brightness by several orders of magnitude. Although our simulations do not reach a steady state, all simulations produce surface brightness values of the same order of magnitude as the observations, with the exact value depending sensitively on the simulation parameters. We conclude that star formation feedback alone is sufficient to explain the origin of the hot halo gas, but measurements of the surface brightness alone do not provide useful diagnostics for the study of galactic star formation.

  10. Chest X Ray?

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are ...

  11. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

  12. Medical X-Rays

    Science.gov (United States)

    ... Benefits The discovery of X-rays and the invention of CT represented major advances in medicine. X- ... in X-ray and CT Examinations — X-ray definition, dose measurement, safety precautions, risk, and consideration with ...

  13. Ultra High Energy Comic Rays in the Cosmic Microwave Background

    CERN Document Server

    Hwang, W-Y Pauchy

    2011-01-01

    We consider the propagation of ultra high energy cosmic rays (UHECR), for energies greater than E > 10^{14} eV but less than E < 10^{26} eV, in the cosmic medium of the Cosmic Microwave Background (CMB). We find that the CMB plays a pivot role in this energy range. As example, the observed "knee(s)" and the "ankle" could be understood in reasonable terms. What we may observe at energy near 10^{25} eV (W^\\pm bursts or Z^0 bursts) is also briefly discussed.

  14. Core-collapse model of broadband emission from SNR RX J1713.7-3946 with thermal X-rays and Gamma-rays from escaping cosmic rays

    CERN Document Server

    Ellison, Donald C; Patnaude, Daniel J; Bykov, Andrei M

    2011-01-01

    We present a spherically symmetric, core-collapse model of SNR RX J1713.7-3946 that includes a hydrodynamic simulation of the remnant evolution coupled to the efficient production of cosmic rays (CRs) by nonlinear diffusive shock acceleration (DSA). High-energy CRs that escape from the forward shock (FS) are propagated in surrounding dense material that simulates either a swept-up, pre-supernova shell or a nearby molecular cloud. The continuum emission from trapped and escaping CRs, along with the thermal X-ray emission from the shocked heated ISM behind the FS, integrated over the remnant, is compared against broadband observations. Our results show conclusively that, overall, the GeV-TeV emission is dominated by inverse-Compton from CR electrons if the supernova is isolated regardless of its type, i.e., not interacting with a >>100 Msun shell or cloud. If the SNR is interacting with a much larger mass >10^4 Msun, pion-decay from the escaping CRs may dominate the TeV emission, although a precise fit at high ...

  15. Testing inflation with the cosmic background radiation

    CERN Document Server

    Bond, J R

    1994-01-01

    In inflation cosmologies, cosmic structure develops through the gravitational instability of the inevitable quantum noise in primordial scalar fields. I show how the acceleration of the universe defines the shape of the primordial spectrum of gravitational metric and scalar field fluctuations. I assess how we can determine the shape and overall amplitude over the five decades or so of spatial wavelengths we can probe, and use current data ... to show how far we are in this program. Broad-band power amplitudes are given for CMB anisotropy detections up to spring 1994 ... I show that COBE band-powers found with full Bayesian analysis of the 53,90,31 a+b GHz first year DMR (and FIRS) maps are in good agreement, and are essentially independent of spectral slope and degree of (sharp) signal-to-noise filtering. Further, after (smooth) optimal signal-to-noise filtering (\\ie Weiner-filtering), the different DMR maps reveal the same large scale features and correlation functions with little dependence upon slope. Howe...

  16. COBE Observations of the Cosmic Infrared Background

    CERN Document Server

    Wright, E L

    2004-01-01

    The Diffuse InfraRed Background Experiment on COBE measured the total infrared signal seen from space at a distance of 1 astronomical unit from the Sun. Using time variations as the Earth orbits the Sun, it is possible to remove most of the foreground signal produced by the interplanetary dust cloud [zodiacal light]. By correlating the DIRBE signal with the column density of atomic hydrogen measured using the 21 cm line, it is possible to remove most of the foreground signal produced by interstellar dust, although one must still be concerned by dust associated with H_2 (molecular gas) and H II (the warm ionized medium). DIRBE was not able to determine the CIRB in the 5-60 micron wavelength range, but did detect both a far infrared background and a near infrared background. The far infrared background has an integrated intensity of about 34 nW/m^2/sr, while the near infrared and optical extragalactic background has about 59 nW/m^2/sr. The Far InfraRed Absolute Spectrophotometer (FIRAS) on COBE has been used to...

  17. LIGO Gravitational Wave Detection, Primordial Black Holes, and the Near-IR Cosmic Infrared Background Anisotropies

    Science.gov (United States)

    Kashlinsky, A.

    2016-06-01

    LIGO's discovery of a gravitational wave from two merging black holes (BHs) of similar masses rekindled suggestions that primordial BHs (PBHs) make up the dark matter (DM). If so, PBHs would add a Poissonian isocurvature density fluctuation component to the inflation-produced adiabatic density fluctuations. For LIGO's BH parameters, this extra component would dominate the small-scale power responsible for collapse of early DM halos at z ≳ 10, where first luminous sources formed. We quantify the resultant increase in high-z abundances of collapsed halos that are suitable for producing the first generation of stars and luminous sources. The significantly increased abundance of the early halos would naturally explain the observed source-subtracted near-IR cosmic infrared background (CIB) fluctuations, which cannot be accounted for by known galaxy populations. For LIGO's BH parameters, this increase is such that the observed CIB fluctuation levels at 2-5 μm can be produced if only a tiny fraction of baryons in the collapsed DM halos forms luminous sources. Gas accretion onto these PBHs in collapsed halos, where first stars should also form, would straightforwardly account for the observed high coherence between the CIB and unresolved cosmic X-ray background in soft X-rays. We discuss modifications possibly required in the processes of first star formation if LIGO-type BHs indeed make up the bulk or all of DM. The arguments are valid only if the PBHs make up all, or at least most, of DM, but at the same time the mechanism appears inevitable if DM is made of PBHs.

  18. Radio-loud AGNs at high redshifts and the cosmic microwave background

    CERN Document Server

    Ghisellini, G; Tavecchio, F; Haardt, F; Sbarrato, T

    2013-01-01

    We discuss how the interaction between the electrons in a relativistic jet and the Cosmic Microwave Background (CMB) affects the observable properties of radio-loud AGN at early epochs. At high z the magnetic energy density in the radio lobes of powerful radio-loud quasars can be exceeded by the energy density of the CMB (because of its (1+z)^4 dependance). In this case, relativistic electrons cool preferentially by scattering off CMB photons, rather than by synchrotron. Thus, sources sharing the same intrinsic properties have different extended radio and X-ray luminosities when located at different z: more distant sources are less luminous in radio and more luminous in X-rays than their closer counterparts. Instead, in compact regions where the local magnetic field still exceeds the CMB in terms of energy density, synchrotron radiation would be unaffected by the presence of the CMB. Such regions include the compact inner jet and the so-called hot spots in the radio lobes. The decrease in radio luminosity is ...

  19. A search for a keV signature of radiatively decaying dark matter with Suzaku XIS observations of the X-ray diffuse background

    Science.gov (United States)

    Sekiya, Norio; Yamasaki, Noriko Y.; Mitsuda, Kazuhisa

    2016-06-01

    We performed the deepest search for an X-ray emission line at between 0.5 and 7 keV from non-baryonic dark matter by the Suzaku XIS. Dark matter associated with the Milky Way was selected as the target to obtain the best signal-to-noise ratio. From the Suzaku archive, we selected 187 data sets of blank-sky regions that were dominated by the X-ray diffuse background. The data sets were from 2005 to 2013. The instrumental responses were adjusted by multiple calibration data sets of the Crab Nebula. We also improved the technique of subtracting lines of instrumental origin. These energy spectra were well described by X-ray emission due to charge exchange around the Solar System, hot plasma in and around the Milky Way, and the superposition of extra-galactic point sources. A signal of a narrow emission-line was searched for, and the significance of detection was evaluated in consideration of the blind search method (the Look-elsewhere Effect). Our results exhibited no significant detection of an emission line feature from dark matter. The 3 σ upper limit for the emission line intensity between 1 and 7 keV was ˜ 10-2 photons cm-2 s-1 sr-1, or ˜ 5 × 10-4 photons cm-2 s-1 sr-1 per M⊙ pc-2, assuming a dark matter distribution with the Galactic rotation curve. The parameters of sterile neutrinos as candidates of dark-matter were also constrained.

  20. Probing the Universe's Tilt with the Cosmic Infrared Background Dipole

    CERN Document Server

    Fixsen, D J

    2011-01-01

    Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypothesis is whether other cosmic dipoles produced by collapsed structures later than last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100 to 500 um wavelength range its spectral energy distribution can provide a probe of its alignment with CMB. This is tested with the COBE FIRAS dataset which is available for such a measurement because of its low noise and frequency resolution important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A...

  1. Cosmic Infrared Background Fluctuations and Zodiacal Light

    CERN Document Server

    Arendt, Richard G; Moseley, S H; Mather, J

    2016-01-01

    We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution, or from IRAC observations of high latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field, at low ecliptic latitude where the zodiacal light intensity varies by factors of $\\sim2$ over the range of solar elongations at which the field can be observed. We find that the white noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that ...

  2. Correlation between galactic HI and the cosmic microwave background

    Science.gov (United States)

    Land, Kate; Slosar, Anže

    2007-10-01

    We revisit the issue of a correlation between the atomic hydrogen gas in our local galaxy and the cosmic microwave background, a detection of which has been claimed in some literature. We cross correlate the 21-cm emission of galactic atomic hydrogen as traced by the Leiden/Argentine/Bonn Galactic Hi survey with the 3-year cosmic microwave background data from the Wilkinson microwave anisotropy probe. We consider a number of angular scales, masks, and Hi velocity slices and find no statistically significant correlation.

  3. Cosmology with cosmic microwave background anisotropy

    Indian Academy of Sciences (India)

    Tarun Sourdeep

    2006-10-01

    Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the early Universe have also been established - `acausally' correlated initial perturbations in a flat, statistically isotropic Universe, adiabatic nature of primordial density perturbations. Direct evidence for gravitational instability mechanism for structure formation from primordial perturbations has been established. In the next decade, future experiments promise to strengthen these deductions and uncover the remaining crucial signature of inflation - the primordial gravitational wave background.

  4. Large Angular Scale Anisotropy in Cosmic Microwave Background Induced by Cosmic Strings

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B.; Caldwell, R.R.; Shellard, E.P.; Stebbins, A.; Veeraraghavan, S. [Department of Physics, University of Wisconsin---Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States)]|[University of Cambridge, Department of Applied Mathematics and Theoretical Physics, Silver Street, Cambridge CB3 9EW (United Kingdom)]|[NASA/Fermilab Astrophysics Center, P.O. Box 500, Batavia, Illinois 60510 (United States)]|[NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

    1996-10-01

    We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on 192 maps, we compute the anisotropy power spectrum for multipole moments l{le}20. By comparing with the observed temperature anisotropy, we set the normalization for the cosmic string mass per unit length {mu}, obtaining {ital G}{mu}/{ital c}{sup 2}=1.05{sub {minus}0.20}{sup +0.35}{times}10{sup {minus}6}, which is consistent with all other observational constraints on cosmic strings. We demonstrate that the anisotropy pattern is consistent with a Gaussian random field on large angular scales. {copyright} {ital 1996 The American Physical Society.}

  5. An Imaging X-Ray Polarimetry Mission

    Science.gov (United States)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Elsner, Ronald; Pavlov, George; Matt, Giorgio; Kaspi, Victoria; Tennant, Allyn; Coppi, Paolo; Wu, Kinwah; Siegmund, Oswald

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful---yet inexpensive---dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsize the important physical and astrophysical questions such a mission would address.

  6. An Imaging X-Ray Polarimetry Mission

    Science.gov (United States)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Elsner, Ronald; Pavlov, George; Matt, Giorgio; Kaspi, Victoria; Tennant, Allyn; hide

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful---yet inexpensive---dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsize the important physical and astrophysical questions such a mission would address.

  7. The Average X-Ray/Gamma-Ray Spectra of Seyfert Galaxies From Ginga and OSSE and the Origin of the Cosmic X-Ray Background

    Science.gov (United States)

    1995-01-01

    Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland; I: aaz@camk.edu.pl W. Neil Johnson E. O. Hulburt Center for Space Research, Naval...For absorption in the re ecting medium, we used the neutral absorption cross sections of Ba lucinska- Church & McCammon (1992) with the elemental...Maehara, M. 1991, PASJ, 43, L1 Ba lucinska- Church , M., & McCammon, D. 1992, ApJ, 400, 699 Bassani, L., et al. 1994, ApJ, in press Della Ceca, R

  8. The TESIS Project: Are Type 2 QSO Hidden in X-Ray Emitting EROs?

    Science.gov (United States)

    Severgnini, P.; Della Ceca, R.; Braito, V.; Saracco, P.; Longhetti, M.; Bender, R.; Drory, N.; Feulner, G.; Hopp, U.; Mannucci, F.; Maraston, C.

    X-ray selected EROs are, on average, the hardest X-ray sources in medium and deep X-ray fields. This coupled with their extremely red colors (R-K > 5) suggest that they represent one of the most promising population where looking for high-luminosity (LX > 1044 erg s-1) and X-ray obscured (NH > 1022 cm-2) type2 AGNs, the so called QSO2 (e.g., [5]; [4]; Mignoli et al. submitted to A&A). These latter are predicted in large density by the synthesis model of the Cosmic X-ray background [9] even if only few observational evidences have been found so far (e.g., [1] and references therein; Caccianiga et al. A&A accepted).

  9. CMB anisotropies generated by cosmic voids and great attractors. [Cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Gonzalez, E.; Sanz, J.L. (Cantabria Univ., Santander (Spain). Dept. Fisica Moderna)

    1990-12-01

    A recent result, based on the potential approximation, concerning the effect of a non-static gravitational potential on the propagation of light, is used to study the influence of compensated and uncompensated non-linear structures on the cosmic microwave background radiation. We obtain the temperature profile as well as the deflection of the microwave photons produced by the cosmic voids and great attractors whose existence has recently been claimed in the literature. (author).

  10. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  11. The cosmic microwave background - A probe of particle physics

    Science.gov (United States)

    Silk, Joseph

    1990-01-01

    The current status of spectral distortions and angular anisotropies in the cosmic microwave background is reviewed, with emphasis on the role played by weakly interacting particle dark matter. Theoretical predictions and recent observational results are described, and prospects for future progress are summarized.

  12. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Liu, Hao; Mertsch, Philipp; Sarkar, Subir

    2014-01-01

    We investigate possible imprints of galactic foreground structures such as the "radio loops" in the derived maps of the cosmic microwave background. Surprisingly, there is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where...

  13. Academic Training: The cosmic microwave background - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    ACADEMIC TRAINING LECTURE REGULAR PROGRAMME 14, 15, 16, 17 and 18 June From 11:00 hrs to 12:00 hrs - Main Auditorium bldg. 500 The cosmic microwave background M. Zaldarriaga / Harvard University, USA ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch

  14. Determining cosmic microwave background structure from its peak distribution

    CERN Document Server

    Kashlinsky, A; Atrio-Barandela, F

    2001-01-01

    We present a new method for time-efficient and accurate extraction of the power spectrum from future cosmic microwave background (CMB) maps based on properties of peaks and troughs of the Gaussian CMB sky. We construct a statistic describing their angular clustering - analogously to galaxies, the 2-point angular correlation function, $\\xi_\

  15. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    DEFF Research Database (Denmark)

    Liu, Hao; Mertsch, Philipp; Sarkar, Subir

    2014-01-01

    We investigate possible imprints of galactic foreground structures such as the "radio loops" in the derived maps of the cosmic microwave background. Surprisingly, there is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where...... due to primordial gravitational waves from inflation....

  16. Real-Time Active Cosmic Neutron Background Reduction Methods

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  17. The First Stars: formation under X-ray feedback

    CERN Document Server

    Hummel, Jacob A; Jeon, Myoungwon; Oliveri, Anthony; Bromm, Volker

    2014-01-01

    We investigate the impact of an ionising X-ray background on metal-free Population III stars within a minihalo at $z\\simeq25$ starting from cosmological initial conditions. Using the smoothed particle hydrodynamics code GADGET-2, we attain sufficient numerical resolution to follow the gas collapsing into the centre of the minihalo up to densities of $n=10^{12}\\,cm^{-3}$, at which point we form sink particles. This allows us to study how the presence of a cosmic X-ray background (CXB) affects the formation of H$_2$ and HD in the gas before it becomes fully molecular. Using a suite of simulations for a range of possible CXB models, we follow each simulation for 5000 yr after the formation of the first sink particle. The CXB provides two competing effects, with X-rays both heating the gas and enhancing its ability to cool by increasing the free electron fraction, allowing more H$_2$ to form. We find that X-ray heating dominates below $n\\sim1\\,cm^{-3}$, while the additional cooling catalysed by X-ray ionisation b...

  18. Quantum dynamics of scalar bosons in a cosmic string background

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Luis B. [Universidade Federal do Maranhao, Departamento de Fisica, Sao Luis, MA (Brazil)

    2015-06-15

    The quantum dynamics of scalar bosons embedded in the background of a cosmic string is considered. In this work, scalar bosons are described by the Duffin-Kemmer-Petiau (DKP) formalism. In particular, the effects of this topological defect in the equation of motion, energy spectrum, and DKP spinor are analyzed and discussed in detail. The exact solutions for the DKP oscillator in this background are presented in closed form. (orig.)

  19. Inhomogeneous Reionization and the Polarization of the Cosmic Microwave Background.

    Science.gov (United States)

    Weller

    1999-12-10

    In a universe with inhomogeneous reionization, the ionized patches create a second-order signal in the cosmic microwave background polarization anisotropy. This signal originates in the coupling of the free-electron fluctuation to the quadruple moment of the temperature anisotropy. We examine the contribution from a simple inhomogeneous reionization model and find that the signal from such a process is below the detectable limits of the Planck Surveyor mission. However, the signal is above the fundamental uncertainty limit from cosmic variance, so that a future detection with a high-accuracy experiment on subarcminute scales is possible.

  20. Giant Rings in the Cosmic Microwave Background Sky

    Science.gov (United States)

    Kovetz, Ely D.; Ben-David, Assaf; Itzhaki, Nissan

    2010-11-01

    We find a unique direction in the cosmic microwave background sky around which giant rings have an anomalous mean temperature profile. This direction is in very close alignment with the afore measured anomalously large bulk flow direction. Using Monte Carlo simulations, we estimate the significance of the giant rings at the 3σ level and the alignment with the bulk flow at 2.5σ. We argue that a cosmic defect seeded by a pre-inflationary particle could explain the giant rings, the large bulk flow, and their alignment.

  1. Cosmic Rays Induced Background Radiation on Board of Commercial Flights

    CERN Document Server

    Pinilla, S; Núñez, L A

    2015-01-01

    The aim of this work is to determine the total integrated flux of cosmic radiation which a commercial aircraft is exposed to along specific flight trajectories. To study the radiation background during a flight and its modulation by effects such as altitude, latitude, exposure time and transient magnetospheric events, we perform simulations based on Magnetocosmics and CORSIKA codes, the former designed to calculate the geomagnetic effects on cosmic rays propagation and the latter allows us to simulate the development of extended air showers in the atmosphere. In this first work, by considering the total flux of cosmic rays from 5 GeV to 1 PeV, we obtained the expected integrated flux of secondary particles on board of a commercial airplane during the Bogot\\'a-Buenos Aires trip by point-to-point numerical integration.

  2. Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates

    CERN Document Server

    Ricotti, Massimo; Mack, Katherine J

    2007-01-01

    We investigate the effect of non-evaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the Cosmic Microwave Background (CMB). Using the third-year WMAP data and FIRAS data we improve existing upper limits on the abundance of PBHs with masses >0.1 Msun by several orders of magnitude. Fitting WMAP3 data with cosmological models that do not allow for non-standard recombination histories, as produced by PBHs or other early energy sources, may lead to an underestimate of the best-fit values of the amplitude of linear density fluctuations (sigma_8) and the scalar spectral index (n_s). Cosmological parameter estimates are affected because models with PBHs allow for larger values of the Thomson scattering optical depth, whose correlation with other parameters may not be correctly taken into account when PBHs are ignored. Values o...

  3. Monte-Carlo Estimation of the Inflight Performance of the GEMS Satellite X-Ray Polarimeter

    Science.gov (United States)

    Kitaguchi, Takao; Tamagawa, Toru; Hayato, Asami; Enoto, Teruaki; Yoshikawa, Akifumi; Kaneko, Kenta; Takeuchi, Yoko; Black, Kevin; Hill, Joanne; Jahoda, Keith; Krizmanic, John; Sturner, Steve; Griffiths, Scott; Kaaret, Philip; Marlowe, Hannah

    2014-01-01

    We report a Monte-Carlo estimation of the in-orbit performance of a cosmic X-ray polarimeter designed to be installed on the focal plane of a small satellite. The simulation uses GEANT for the transport of photons and energetic particles and results from Magboltz for the transport of secondary electrons in the detector gas. We validated the simulation by comparing spectra and modulation curves with actual data taken with radioactive sources and an X-ray generator. We also estimated the in-orbit background induced by cosmic radiation in low Earth orbit.

  4. CZT in Space Based Hard-X-ray Astronomy

    CERN Document Server

    Garson, A; Weidenspointner, G; Novikova, E I; Grindlay, J; Hong, J; Jung, I V

    2006-01-01

    One of the key aspects of a detector material for space-borne hard X-ray and gamma-ray telescopes is the rate of prompt and delayed background events generated inside the material by charged and neutral particles striking the detector. These particles are Cosmic Rays, particles trapped in Earth's magnetic field, and secondaries from Cosmic Ray interacting with the atmosphere and the spacecraft. Here, we present a preliminary study of Cadmium Zinc Telluride (CZT) and its behaviour in space environments. We have used the simulation package MGGPOD to estimate the background of the CZT detectors in the proposed Energetic X-ray Imaging Survey Telescope (EXIST) for possible orbital parameters. The EXIST mission will make use of 6 square meters of 0.5 cm thick CZT detectors to record cosmic X-rays in the energy range from 10 keV to 600 keV. The detectors will be shielded by a fully or partly active shield. For the specific detector and shielding geometry considered here and an orbit with a low (7 deg) inclination, t...

  5. Relation of large-scale coronal X-ray structure and cosmic rays. I - Sources of solar wind streams as defined by X-ray emission and H-alpha absorption features

    Science.gov (United States)

    Krieger, A. S.; Nolte, J. T.; Sullivan, J. D.; Lazarus, A. J.; Mcintosh, P. S.; Gold, R. E.; Roelof, E. C.

    1975-01-01

    The large-scale structure of the corona and the interplanetary medium during Carrington rotations 1601-1607 is discussed relative to recurrent high-speed solar wind streams and their coronal sources. Only streams A, C, D, and F recur on more than one rotation. Streams A and D are associated with coronal holes, while C and F originate in the high corona (20-50 solar radii) over faint X-ray emissions. The association of the streams with holes is confirmed by earlier findings that there are no large equatorial holes without an associated high-speed stream and that the area of the equatorial region of coronal holes is highly correlated with the maximum velocity observed in the associated stream near 1 AU.

  6. The Evolution of Normal Galaxy X-ray Emission Through Cosmic History: Constraints from the 6 Ms Chandra Deep Field-South

    CERN Document Server

    Lehmer, B D; Mineo, S; Brandt, W N; Eufrasio, R T; Fragos, T; Hornschemeier, A E; Luo, B; Xue, Y Q; Bauer, F E; Gilfanov, M; Ranalli, P; Schneider, D P; Shemmer, O; Tozzi, P; Trump, J R; Vignali, C; Wang, J -X; Yukita, M; Zezas, A

    2016-01-01

    We present measurements of the evolution of normal-galaxy X-ray emission from $z \\approx$ 0-7 using local galaxies and galaxy samples in the 6 Ms Chandra Deep Field-South (CDF-S) survey. The majority of the CDF-S galaxies are observed at rest-frame energies above 2 keV, where the emission is expected to be dominated by X-ray binary (XRB) populations; however, hot gas is expected to provide small contributions to the observed- frame < 1 keV emission at $z < 1$. We show that a single scaling relation between X-ray luminosity ($L_{\\rm X}$) and star-formation rate (SFR) is insufficient for characterizing the average X-ray emission at all redshifts. We establish that scaling relations involving not only SFR, but also stellar mass ($M_\\star$) and redshift, provide significantly improved characterizations of the average X-ray emission from normal galaxy populations at $z \\approx$ 0-7. We further provide the first empirical constraints on the redshift evolution of X-ray emission from both low-mass XRB (LMXB) an...

  7. Extremity x-ray

    Science.gov (United States)

    ... degenerative) Bone tumor Broken bone (fracture) Dislocated bone Osteomyelitis (infection) Arthritis Other conditions for which the test ... Bone tumor Bone x-ray Broken bone Clubfoot Osteomyelitis X-ray Review Date 7/3/2016 Updated ...

  8. Abdominal x-ray

    Science.gov (United States)

    ... are, or may be, pregnant. Alternative Names Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also ...

  9. Measuring cosmological bulk flows via the kinematic Sunyaev-Zel'dovich effect in the upcoming cosmic microwave background maps

    CERN Document Server

    Kashlinsky, A

    2000-01-01

    We propose a new method to measure the possible large-scale bulk flows in the Universe from the cosmic microwave background (CMB) maps from the upcoming missions, MAP and Planck. This can be done by studying the statistical properties of the CMB temperature field at many X-ray cluster positions. At each cluster position, the CMB temperature fluctuation will be a combination of the Sunyaev-Zeldovich (SZ) kinematic and thermal components, the cosmological fluctuations and the instrument noise term. When averaged over many such clusters the last three will integrate down, whereas the first one will be dominated by a possible bulk flow component. In particular, we propose to use all-sky X-ray cluster catalogs that should (or could) be available soon from X-ray satellites, and then to evaluate the dipole component of the CMB field at the cluster positions. We show that for the MAP and Planck mission parameters the dominant contributions to the dipole will be from the terms due to the SZ kinematic effect produced b...

  10. X-ray galaxy clusters abundance and mass temperature scaling

    CERN Document Server

    Ilic, Stéphane; Douspis, Marian

    2015-01-01

    The abundance of clusters of galaxies is known to be a potential source of cosmological constraints through their mass function. In the present work, we examine the information that can be obtained from the temperature distribution function of X-ray clusters. For this purpose, the mass-temperature ($M$-$T$) relation and its statistical properties are critical ingredients. Using a combination of cosmic microwave background (CMB) data from Planck and our estimations of X-ray cluster abundances, we use Markov chain Monte Carlo (MCMC) techniques to estimate the $\\Lambda$CDM cosmological parameters and the mass to X-ray temperature scaling relation simultaneously. We determine the integrated X-ray temperature function of local clusters using flux-limited surveys. A local comprehensive sample was build from the BAX X-ray cluster database, allowing us to estimate the local temperature distribution function above $\\sim$1 keV. We model the expected temperature function from the mass function and the $M$-$T$ scaling re...

  11. International Cooperation of the Cosmic Infrared Background Experiment

    Science.gov (United States)

    Lee, D.-H.; Nam, U.-W.; Lee, S.; Jin, H.; Yuk, I.-S.; Kim, K.-H.; Pak, S.

    2006-12-01

    A Korean team (Korea Astronomy and Space Science Institute, Korea Basic Science Institute, and Kyung Hee University) takes part in an international cooperation project called CIBER (Cosmic Infrared Background ExpeRiment), which has begun with Jet Propulsion Laboratory (JPL) in USA and Institute of Space and Astronautical Science (ISAS) in Japan. CIBER is a rocket-borne instrument, of which the scientific goal is to measure the cosmic near-infrared extra-galactic background to search for signatures of primordial galaxy formation. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The Korean team is in charge of the ground support electronics and manufacturing of optical parts of the narrow-band spectrometer, which will provide excellent opportunities for science and technology to Korean infrared groups.

  12. Cosmic microwave background anisotropies seeded by incoherent sources

    CERN Document Server

    Riazuelo, A; Riazuelo, Alain; Deruelle, Nathalie

    2000-01-01

    The cosmic microwave background anisotropies produced by active seeds, such as topological defects, have been computed recently for a variety of models by a number of authors. In this paper we show how the generic features of the anisotropies caused by active, incoherent, seeds (that is the absence of acoustic peaks at small scales) can be obtained semi-analytically, without entering into the model dependent details of their formation, structure and evolution.

  13. Can decaying particle explain cosmic infrared background excess?

    Directory of Open Access Journals (Sweden)

    Kazunori Kohri

    2017-09-01

    Full Text Available Recently the CIBER experiment measured the diffuse cosmic infrared background (CIB flux and claimed an excess compared with integrated emission from galaxies. We show that the CIB spectrum can be fitted by the additional photons produced by the decay of a new particle. However, it also contributes too much to the anisotropy of the CIB, which is in contradiction with the anisotropy measurements by the CIBER and Hubble Space Telescope.

  14. Can decaying particle explain cosmic infrared background excess?

    Science.gov (United States)

    Kohri, Kazunori; Moroi, Takeo; Nakayama, Kazunori

    2017-09-01

    Recently the CIBER experiment measured the diffuse cosmic infrared background (CIB) flux and claimed an excess compared with integrated emission from galaxies. We show that the CIB spectrum can be fitted by the additional photons produced by the decay of a new particle. However, it also contributes too much to the anisotropy of the CIB, which is in contradiction with the anisotropy measurements by the CIBER and Hubble Space Telescope.

  15. Primary and Secondary Anisotropies of Cosmic Microwave Background

    Science.gov (United States)

    Seljak, Uros

    2002-01-01

    The three main topics we proposed to do are linear calculations (continuing development of CMBFAST), nonlinear calculations of gas physics relevant to Cosmic Microwave Background (CMB) (Sunyaev-Zeldovich effect, etc.) and nonlinear effects on CMB due to dark matter (gravitational lensing, etc.). We describe each of these topics, as well as additional topics PI and his group worked on that are related to the topics in the proposal.

  16. The Cosmic Microwave Background State of the Art

    CERN Document Server

    Barreiro, R B

    2000-01-01

    We review the current status of the cosmic microwave background (CMB) radiation, including a revision of some basic theoretical aspects, a summary of anisotropy detections and CMB experiments, and a description of some relevant characteristics of the microwave foregrounds. We also discuss the different estimators proposed in the literature to detect non-Gaussianity and outline the basis of some reconstruction methods that have been applied to the CMB.

  17. The effect of hot gas in early-type galaxies on the cosmic microwave background

    Science.gov (United States)

    Trester, Jeffrey J.; Canizares, Claude R.

    1989-01-01

    The effects on the cosmic microwave background which are due to Compton scattering by the hot gas contained in early-type galaxies (the Sunyaev-Zeldovich effect) are computed. Using the known properties of the gas deduced from X-ray observations, it is found that the fractional attenuation DeltaT/T at the center of a gas-rich galaxy is likely to be less than 10 to the -5th, which is just below current limits of detectability. A distribution function is derived for the attenuation which is due to a population of early-type galaxies out to some redshift and the expected rms fluctuations in the background on subarcmin scales are computed. These fluctuations are comparable to those intrinsic to the microwave background in the 'cold dark matter' scenario on these angular scales, but they fall orders of magnitude below the detection limits and below the level of fluctuations expected from nonlinear density perturbations at the epoch of galaxy formation.

  18. Hard X-ray Spectroscopy of Obscured AGN with NuSTAR

    Science.gov (United States)

    Balokovic, Mislav; Harrison, Fiona; NuSTAR Extragalactic Surveys Team

    2017-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the hard X-ray band, up to 79 keV, with unprecedented spatial resolution and sensitivity. As a part of its extragalactic program, NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT), selecting even the most obscured local AGN. I will highlight some of the results based on broadband X-ray spectroscopy of individual targets and present my work on the large representative sample of more than a hundred nearby obscured AGN, which constitutes the largest available atlas of hard X-ray spectra of obscured AGN to date. The high quality of the data allows us to probe the details of AGN structures such as the X-ray-emitting corona and the toroidal obscurer in the under-explored spectral window above 10 keV. I will present both phenomenological results important for synthesis models of the cosmic X-ray background, and a novel approach for constraining the geometry of the gas surrounding the supermassive black hole (including the accretion disk, the broad-line region, and the torus) from the hard X-ray band. Finally, I will discuss how what we learned from this survey of local AGN relates to deeper high-redshift X-ray surveys and AGN structure probes at other wavelengths.

  19. An X-ray Imaging Survey of Quasar Jets -- Testing the Inverse Compton Model

    CERN Document Server

    Marshall, H L; Schwartz, D A; Murphy, D W; Lovell, J E J; Worrall, D M; Birkinshaw, M; Perlman, E S; Godfrey, L; Jauncey, D L

    2011-01-01

    We present results from continued Chandra X-ray imaging and spectroscopy of a flux-limited sample of flat spectrum radio-emitting quasars with jet-like extended structure. X-rays are detected from 24 of the 39 jets observed so far. We compute the distribution of alpha_rx, the spectral index between the X-ray and radio bands, showing that it is broad, extending at least from 0.8 to 1.2. While there is a general trend that the radio brightest jets are detected most often, it is clear that predicting the X-ray flux from the radio knot flux densities is risky so a shallow X-ray survey is the most effective means for finding jets that are X-ray bright. We test the model in which the X-rays result from inverse Compton (IC) scattering of cosmic microwave background (CMB) photons by relativistic electrons in the jet moving with high bulk Lorentz factor nearly along the line of sight. Depending on how the jet magnetic fields vary with z, the observed X-ray to radio flux ratios do not follow the redshift dependence exp...

  20. Searching for Dark Matter with X-ray Observations of Local Dwarf Galaxies

    CERN Document Server

    Jeltema, Tesla E

    2008-01-01

    A generic feature of weakly interacting massive particle (WIMP) dark matter models is the emission of photons over a broad energy band resulting from the stable yields of dark matter pair annihilation. Inverse Compton scattering off cosmic microwave background photons of energetic electrons and positrons produced in dark matter annihilation is expected to produce significant diffuse X-ray emission. Dwarf galaxies are ideal targets for this type of dark matter search technique, being nearby, dark matter dominated systems free of any astrophysical diffuse X-ray background. In this paper, we present the first systematic study of X-ray observations of local dwarf galaxies aimed at the search for WIMP dark matter. We outline the optimal energy and angular ranges for current telescopes, and analyze the systematic uncertainties connected to electron/positron diffusion. We do not observe any significant X-ray excess, and translate this null result into limits on the mass and pair annihilation cross section for partic...

  1. Synergy between X-ray and infrared observations

    CERN Document Server

    Alexander, D M

    2016-01-01

    We briefly review the synergy between X-ray and infrared observations for Active Galactic Nuclei (AGNs) detected in cosmic X-ray surveys, primarily with XMM-Newton, Chandra, and NuSTAR. We focus on two complementary aspects of this X-ray-infrared synergy (1) the identification of the most heavily obscured AGNs and (2) the connection between star formation and AGN activity. We also briefly discuss future prospects for X-ray-infrared studies over the next decade.

  2. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.A.S. [Departamento de Astronomia, Universidade de São Paulo, 55080-900, São Paulo, SP (Brazil); Graef, L.L. [Instituto de Física, Universidade de São Paulo, Rua do Matão travessa R, 05508-090, São Paulo, SP (Brazil); Pavón, D. [Departamento de Física, Universidad Autónoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Basilakos, Spyros, E-mail: jas.lima@iag.usp.br, E-mail: leilagraef@usp.br, E-mail: diego.pavon@uab.es, E-mail: svasil@academyofathens.gr [Academy of Athens, Research Center for Astronomy and Applied Mathematics, Soranou Efesiou 4, 11527, Athens (Greece)

    2014-10-01

    A cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons–Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current 'quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.

  3. X-Ray Synchrotron Emission from 10-100 TeV Cosmic-Ray Electrons in the Supernova Remnant SN 1006

    CERN Document Server

    Allen, G E; Gotthelf, E V

    2001-01-01

    We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band from 0.12 to 17 keV. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kT = 0.6 keV, an ionization timescale n0t = 9 x 10^9 s / cm^3, and a relative elemental abundance of silicon that is 10-18 times larger than the solar abundance. The nonthermal X-ray spectrum is described by a broken power law model with low- and high-energy photon indices Gamma_1 = 2.1 and Gamma_2 = 3.0, respectively. Since the nonthermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate previous claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larger than previous estimates of about 1 x 10^-5 G and arbitra...

  4. Examination of Libby, Montana, Fill Material for Background Levels of Amphibole from the Rainy Creek Complex Using Scanning Electron Microscopy and X-Ray Microanalysis

    Science.gov (United States)

    Adams, David T.; Langer, William H.; Hoefen, Todd M.; Van Gosen, Bradley S.; Meeker, Gregory P.

    2010-01-01

    Natural background levels of Libby-type amphibole in the sediment of the Libby valley in Montana have not, up to this point, been determined. The purpose of this report is to provide the preliminary findings of a study designed by both the U.S. Geological Survey and the U.S. Environmental Protection Agency and performed by the U.S. Geological Survey. The study worked to constrain the natural background levels of fibrous amphiboles potentially derived from the nearby Rainy Creek Complex. The material selected for this study was sampled from three localities, two of which are active open-pit sand and gravel mines. Seventy samples were collected in total and examined using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. All samples contained varying amounts of feldspars, ilmenite, magnetite, quartz, clay minerals, pyroxene minerals, and non-fibrous amphiboles such as tremolite, actinolite, and magnesiohornblende. Of the 70 samples collected, only three had detectable levels of fibrous amphiboles compatible with those found in the rainy creek complex. The maximum concentration, identified here, of the amphiboles potentially from the Rainy Creek Complex is 0.083 percent by weight.

  5. X-Ray Supernovae

    CERN Document Server

    Immler, S; Immler, Stefan; Lewin, Walter H.G.

    2002-01-01

    We present a review of X-ray observations of supernovae (SNe). By observing the (~0.1--100 keV) X-ray emission from young SNe, physical key parameters such as the circumstellar matter (CSM) density, mass-loss rate of the progenitor and temperature of the outgoing and reverse shock can be derived as a function of time. Despite intensive search over the last ~25 years, only 15 SNe have been detected in X-rays. We review the individual X-ray observations of these SNe and discuss their implications as to our understanding of the physical processes giving rise to the X-ray emission.

  6. Evidence for gravitational lensing of the cosmic microwave background polarization from cross-correlation with the cosmic infrared background.

    Science.gov (United States)

    Ade, P A R; Akiba, Y; Anthony, A E; Arnold, K; Atlas, M; Barron, D; Boettger, D; Borrill, J; Borys, C; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Le Jeune, M; Lee, A T; Leitch, E M; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Poletti, D; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K; Schanning, I; Schenck, D E; Sherwin, B D; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tikhomirov, A; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2014-04-04

    We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0σ and indication of the presence of a lensing B-mode signal at a significance of 2.3σ. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.

  7. Evidence for Gravitational Lensing of the Cosmic Microwave Background Polarization from Cross-correlation with the Cosmic Infrared Background

    CERN Document Server

    Ade, P A R; Anthony, A E; Arnold, K; Barron, D; Boettger, D; Borrill, J; Borys, C; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Jeune, M Le; Lee, A T; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K; Schanning, I; Schenck, D E; Sherwin, B D; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tikhomirov, A; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

    2013-01-01

    We reconstruct the gravitational lensing convergence signal from Cosmic Microwave Background (CMB) polarization data taken by the POLARBEAR experiment and cross-correlate it with Cosmic Infrared Background (CIB) maps from the Herschel satellite. From the cross-spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0$\\sigma$ and evidence for the presence of a lensing $B$-mode signal at a significance of 2.3$\\sigma$. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null-tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.

  8. Measuring the Redshift Dependence of The Cosmic Microwave Background Monopole Temperature With Planck Data

    Science.gov (United States)

    De Martino, I.; Atrio-Barandela, F.; Da Silva, A.; Ebling, H.; Kashlinsky, A.; Kocevski, D.; Martins, C. J. A. P.

    2012-01-01

    We study the capability of Planck data to constrain deviations of the cosmic microwave background (CMB) blackbody temperature from adiabatic evolution using the thermal Sunyaev-Zeldovich anisotropy induced by clusters of galaxies. We consider two types of data sets depending on how the cosmological signal is removed: using a CMB template or using the 217 GHz map. We apply two different statistical estimators, based on the ratio of temperature anisotropies at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency. The ratio method is biased if CMB residuals with amplitude approximately 1 microK or larger are present in the data, while residuals are not so critical for the fit method. To test for systematics, we construct a template from clusters drawn from a hydro-simulation included in the pre-launch Planck Sky Model. We demonstrate that, using a proprietary catalog of X-ray-selected clusters with measured redshifts, electron densities, and X-ray temperatures, we can constrain deviations of adiabatic evolution, measured by the parameter a in the redshift scaling T (z) = T0(1 + z)(sup 1-alpha), with an accuracy of sigma(sub alpha) = 0.011 in the most optimal case and with sigma alpha = 0.018 for a less optimal case. These results represent a factor of 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.

  9. Wavelet-Bayesian inference of cosmic strings embedded in the cosmic microwave background

    CERN Document Server

    McEwen, J D; Peiris, H V; Wiaux, Y; Ringeval, C; Bouchet, F R

    2016-01-01

    Cosmic strings are a well-motivated extension to the standard cosmological model and could induce a subdominant component in the anisotropies of the cosmic microwave background (CMB), in addition to the standard inflationary component. The detection of strings, while observationally challenging, would provide a direct probe of physics at very high energy scales. We develop a new framework for cosmic string inference, constructing a Bayesian analysis in wavelet space where the string-induced CMB component has distinct statistical properties to the standard inflationary component. Our wavelet-Bayesian framework provides a principled approach to compute the posterior distribution of the string tension $G\\mu$ and the Bayesian evidence ratio comparing the string model to the standard inflationary model. Furthermore, we present a technique to recover an estimate of any string-induced CMB map embedded in observational data. Using Planck-like simulations we demonstrate the application of our framework and evaluate it...

  10. Spectroscopy in X-ray astronomy

    Science.gov (United States)

    Andresen, R.

    1981-01-01

    Detailed features in cosmic X-ray sources and their associated temporal variation over a wide energy range were studied. Excess emission and absorption at approximately 6 to 7 kiloelectron volts in the spectra of supernova remnants, binary X-ray sources, and clusters of galaxies were observed. A gas scintillation proportional counter (GSPC) will be used as the detector system. In the gas scintillator the principal limitation is due to the statistics of the initial ionization process only.

  11. Multiple Cosmic Collisions and the Microwave Background Power Spectrum

    CERN Document Server

    Kozaczuk, Jonathan

    2012-01-01

    Collisions between cosmic bubbles of different vacua are a generic feature of false vacuum eternal inflation scenarios. While previous studies have focused on the consequences of a single collision event in an observer's past, we begin here an investigation of the more general scenario allowing for many "mild" collisions intersecting our past light cone (and one another). We discuss the general features of multiple collision scenarios and consider their impact on the cosmic microwave background (CMB) temperature power spectrum, treating the collisions perturbatively. In a large class of models, one can approximate a multiple collision scenario as a superposition of individual collision events governed by nearly isotropic and scale-invariant distributions, most appearing to take up less than half of the sky. In this case, the shape of the expected CMB temperature spectrum maintains statistical isotropy and typically features a dramatic increase in power in the low multipoles relative to that of the best-fit $\\...

  12. The Properties of the Diffuse X-ray Background from the DXL sounding rocket mission (plus ROSAT, XMM-Newton and Suzaku data)

    Science.gov (United States)

    Galeazzi, Massimiliano

    2017-08-01

    Understanding the properties of the different components of the Diffuse X-ray Background (DXB) is made particularly difficult by their similar spectral signature.The University of Miami has been working on disentangling the different DXB components for many years, using a combination of proprietary and archival data from XMM-Newton, Suzaku, and Chandra, and a sounding rocket mission (DXL) specifically designed to study the properties of Local Hot Bubble (LHB) and Solar Wind Charge eXchange (SWCX) using their spatial signature. In this talk we will present:(a) Results from the DXL mission, specifically launch #2, to study the properties of the SWCX and LHB (and GH) and their contribution to the ROSAT All Sky Survey Bands(b) Results from a Suzaku key project to characterize the SWCX and build a semi-empirical model to predict the SWCX line emission for any time, any direction. A publicly available web portal for the model will go online by the end of the year(c) Results from XMM-Newton deep surveys to study the angular correlation of the Warm-Hot Intergalactic Medium (WHIM) in the direction of the Chandra Deep Field South.DXL launch #3, schedule for January 2018 and the development of the DXG sounding rocket mission to characterize the GH-CGM emission using newly developed micropore optics will also be discussed.

  13. Cosmic microwave background and first molecules in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Signore, Monique [LERMA, Observatoire de Paris, Paris (France); Puy, Denis [University of Montpellier II, CNRS UMR 5024, GRAAL CC72, Montpellier (France)

    2009-01-15

    Besides the Hubble expansion of the universe, the main evidence in favor of the big-bang theory was the discovery, by Penzias and Wilson, of the cosmic microwave background (hereafter CMB) radiation. In 1990, the COBE satellite (Cosmic Background Explorer) revealed an accurate black-body behavior with a temperature around 2.7 K. Although the microwave background is very smooth, the COBE satellite did detect small variations - at the level of one part in 100 000 - in the temperature of the CMB from place to place in the sky. These ripples are caused by acoustic oscillations in the primordial plasma. While COBE was only sensitive to long-wavelength waves, the Wilkinson Microwave Anisotropy Probe (WMAP) - with its much higher resolution - reveals that the CMB temperature variations follow the distinctive pattern predicted by cosmological theory. Moreover, the existence of the microwave background allows cosmologists to deduce the conditions present in the early stages of the big bang and, in particular, helps to account for the chemistry of the universe. This report summarizes the latest measurements and studies of the CMB with the new calculations about the formation of primordial molecules. The PLANCK mission - planned to be launched in 2009 - is also presented. (orig.)

  14. The Cosmic Background Radiation circa nu2K

    CERN Document Server

    Bond, J R; Prunet, S; Ade, P; Balbi, A; Bock, J J; Borrill, J; Boscaleri, A; Coble, K; Crill, B P; De Bernardis, P; Farese, P; Ferreira, P; Ganga, K; Giacometti, M; Hanany, S; Hivon, E; Hristov, V V; Iacoangeli, A; Jaffe, A; Lange, A; Lee, A; Martinis, L; Masi, S; Mauskopf, P D; Melchiorri, A; Montroy, T; Netterfield, C B; Oh, S; Pascale, E; Piacentini, F; Rabii, B; Rao, S; Richards, P; Romeo, G; Ruhl, J E; Scaramuzzi, F; Sforza, D M; Smoot, G F; Stompor, R; Winant, C; Wu, P

    2000-01-01

    We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima CMB balloon experiments. The inflation-based cosmic structure formation paradigm we have been operating with for two decades has never been in better shape. Here we primarily focus on a simplified inflation parameter set, {omega_b,omega_{cdm},Omega_{tot}, Omega_\\Lambda,n_s,\\tau_C, \\sigma_8}. Combining all of the current CMB+LSS data points to the remarkable conclusion that the local Hubble patch we can access has little mean curvature (Omega_{tot}=1.08\\pm 0.06) and the initial fluctuations were nearly scale invariant (n_s=1.03\\pm 0.08), both predictions of (non-baroque) inflation theory. The baryon density is found to be slightly larger than that preferred by independent Big Bang Nucleosynthesis estimates (omega_b=0.030\\pm 0.005 cf. 0.019\\pm 0.002). The CDM density is in th...

  15. Magneto-optic effects of the Cosmic Microwave Background

    CERN Document Server

    Ejlli, Damian

    2016-01-01

    Generation of magneto-optic effects by the cosmic microwave background (CMB) in the presence of cosmic magnetic fields is studied. Four mechanisms which generate polarization of the CMB such as the Cotton-Mouton effect, the vacuum polarization in external magnetic field, the photon-pseudoscalar mixing in external magnetic field and the Faraday effect are studied. Considering the CMB linearly polarized at decoupling time due to Thomson scattering, it is shown that second order effects in the magnetic field amplitude such as the Cotton-Mouton effect in plasma and the vacuum polarization (Euler-Heisenberg term) in cosmic magnetic field, would generate elliptic polarization of the CMB at post decoupling time depending on the photon frequency and magnetic field strength. The Cotton-Mouton effect in plasma turns out to be the dominant effect in the generation of CMB elliptic polarization in the low frequency part while the vacuum polarization in magnetic field is the dominant process in the high frequency part. The...

  16. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes.

  17. Probing the Universe's Tilt with the Cosmic Infrared Background Dipole

    Science.gov (United States)

    Fixsen, D. J.; Kashlinsky, A.

    2011-06-01

    Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypotheses is whether other cosmic dipoles produced by collapsed structures later than the last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100-500 μm wavelength range its spectral energy distribution can provide a probe of its alignment with the CMB. This is tested with the COBE FIRAS data set which is available for such a measurement because of its low noise and frequency resolution which are important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A similar analysis is performed with DIRBE, which—because of the limited frequency coverage—provides a poorer data set. We discuss strategies for measuring the CIB dipole with future instruments to probe the tilt and apply it to the Planck, Herschel, and the proposed Pixie missions. We demonstrate that a future FIRAS-like instrument with instrument noise a factor of ~10 lower than FIRAS would make a statistically significant measurement of the CIB dipole. We find that the Planck and Herschel data sets will not allow a robust CIB dipole measurement. The Pixie instrument promises a determination of the CIB dipole and its alignment with either the CMB dipole or the dipole galaxy acceleration vector.

  18. Self-Similar Symmetry Model and Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Tomohide eSonoda

    2016-05-01

    Full Text Available In this paper, we present the self-similar symmetry (SSS model that describes the hierarchical structure of the universe. The model is based on the concept of self-similarity, which explains the symmetry of the cosmic microwave background (CMB. The approximate length and time scales of the six hierarchies of the universe---grand unification, electroweak unification, the atom, the pulsar, the solar system, and the galactic system---are derived from the SSS model. In addition, the model implies that the electron mass and gravitational constant could vary with the CMB radiation temperature.

  19. Prospectives on Direct Detection of the Cosmic Neutrino Background

    Science.gov (United States)

    Li, Yu-Feng

    2017-09-01

    The cosmic neutrino background (CνB) is a fundamental prediction of the hot Big Bang cosmology. Although cosmological observations provide indirect evidence for the existence of the CνB, we still lack a direct detection in a laboratory. In this work we present the current possible detection methods of the CνB. The method of CνB captures on the radioactive decaying nuclei is particularly emphasized in light of the PTOLEMY project. We stress that such direct measurements might not be hopeless in the long term.

  20. Fingerprints of Galactic Loop I on the Cosmic Microwave Background

    CERN Document Server

    Liu, Hao; Sarkar, Subir

    2014-01-01

    We investigate possible imprints of galactic foreground structures such as the `radio loops' in the derived maps of the cosmic microwave background. Surprisingly there is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where emission by dust dominates. This suggests the mechanism is magnetic dipole radiation from dust grains enriched by metallic iron, or ferrimagnetic molecules. This new foreground we have identified is present at high galactic latitudes, and potentially dominates over the expected B-mode polarisation signal due to primordial gravitational waves from inflation.

  1. Cosmic microwave background anisotropies with mixed isocurvature perturbations.

    Science.gov (United States)

    Trotta, R; Riazuelo, A; Durrer, R

    2001-12-01

    In the light of the recent high quality data of the cosmic microwave background anisotropies, several estimations of cosmological parameters have been published. We study to what extent these estimations depend on assumptions about the initial conditions of the cosmological perturbations, which are usually supposed to be adiabatic. We show that, for more generic initial conditions, not only the best fit values are very different but the allowed parameter range enlarges dramatically. This raises the question which cosmological information (matter content of the Universe vs physics of inflation) can be reliably extracted from these data.

  2. Dark energy and the cosmic microwave background radiation

    Science.gov (United States)

    Dodelson, S.; Knox, L.

    2000-01-01

    We find that current cosmic microwave background anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including a cosmological constant). Other lines of argument indicate that the energy density of nonrelativistic matter is much less than critical. Together, these results are evidence, independent of supernovae data, for dark energy in the Universe.

  3. The cosmic infrared background resolved by Spitzer - Contributions of mid-infrared galaxies to the far-infrared background

    NARCIS (Netherlands)

    Dole, H; Lagache, G; Puget, JL; Caputi, KI; Fernandez-Conde, N; Le Floc'h, E; Papovich, C; Perez-Gonzalez, PG; Rieke, GH; Blaylock, M

    Aims. We quantify the contributions of 24 mu m galaxies to the Far-Infrared ( FIR) Background at 70 and 160 mu m. We provide new estimates of the Cosmic Infrared Background ( CIB), and compare it with the Cosmic Optical Background ( COB). Methods. Using Spitzer data at 24, 70 and 160 mu m in three

  4. Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations

    CERN Document Server

    Ueda, Yoshihiro; Hasinger, Guenther; Miyaji, Takamitsu; Watson, Michael G

    2014-01-01

    We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5--2 keV) and/or hard ($>2$ keV) band. We utilize a maximum likelihood method to reproduce the count-rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broad band spectra of AGNs including reflection components from tori based on the luminosity and redshift dependent unified scheme. We find that the shape of the XLF at $z \\sim 1-3$ is significantly different from that in the local universe, for which the luminosity dependent density evolution model gives much better description...

  5. Cosmic ray composition measurements and cosmic ray background free gamma-ray observations with Cherenkov telescopes

    CERN Document Server

    Neronov, A; Vovk, Ie; Mirzoyan, R

    2016-01-01

    Muon component of extensive air showers (EAS) initiated by cosmic ray particles carries information on the primary particle identity. We show that the muon content of EAS could be measured in a broad energy range from 10-100 TeV up to ultra-high-energy cosmic ray range using wide field-of-view imaging atmospheric Cherenkov telescopes observing strongly inclined or nearly horizontal EAS from the ground of from high altitude. Cherenkov emission from muons in such EAS forms a distinct component (halo or tail) of the EAS image in the telescope camera. We show that detection of the muon signal could be used to measure composition of the cosmic ray spectrum in the energy ranges of the knee, the ankle and of the Galactic-to-extragalactic transition. It could also be used to veto the cosmic ray background in gamma-ray observations. This technique provides a possibility for up to two orders of magnitude improvement of sensitivity for gamma-ray flux in the energy band above 10 PeV, compared to KASCADE-Grande, and an or...

  6. The influence of 1.4-naphtoquinone derivative and of vitamin E on nitroso-oxidative processes in digestive organ mucous membranes under the conditions of cyclooxygenase blockage, and against the background of low intensity X-ray irradiation

    Directory of Open Access Journals (Sweden)

    Ilnytska Khrystyna

    2016-09-01

    Full Text Available In recent years, the influence of chronic low intensity irradiation on the human body has increased. This is mediated not only by the consequences of technogenic catastrophies, but also due to application of radiation therapy of of radiation usage in industry. Hence, we investigated the influence of 1.4-naphtoquinone and vitamin Е on the nitroso-oxidative processes in the digestive organ mucous membranes, while affected by low intensity X-ray irradiation alone and in combination with the experimental blockage of COX, in rats. Our results show that X-ray irradiation of a total dose of 20 sGy during twenty days, induced an increase of the oxidative processes, as well as an increase in the activity of iNOS and myeloperoxidase in the mucous membranes of the stomach, small and large intestine. Both the effect of vitamin E and a 1.4-naphtoquinone derivative on the background of low intensity X-ray irradiation, and under the simultaneous effect of X-ray irradiation and COX blockage, brought about a decrease of the level of oxidative processes and of iNOS activity, whereas MPO activity increased. We also noted that the effect of vitamin E on the background of X-ray irradiation more significantly increased both the activity of SOD and catalase, when compared to the induced effect of the 1.4-naphtoquinone derivative. Under the conditions of COX-1/COX-2 blockage (as induced by way of indomethacin administration, against the background of X-ray irradiation, the content of TBA-active products (in the stomach and small intestine mucous membranes, the level of iNOS activity and the sum of nitrites and nitrates, were lower than that of independent effect. Тaking into account the prominent antioxidant and anti-inflammatory attributes of 1.4-naphtoquinone-3-[3-(3.5-di-tret-butyl-4-hydroxy-phenyl-1.4-dihydronaphtalene-2-aminoil] butyrate, when compared to the effect of sole administration of vitamin E, both under the conditions of X-ray irradiation alone, and

  7. Constraining the redshift evolution of the Cosmic Microwave Background black-body temperature with PLANCK data

    CERN Document Server

    de Martino, I; Atrio-Barandela, F; Ebeling, H; Kashlinsky, A; Kocevski, D; Martins, C J A P

    2015-01-01

    We constrain the deviation of adiabatic evolution of the Universe using the data on the Cosmic Microwave Background (CMB) temperature anisotropies measured by the {\\it Planck} satellite and a sample of 481 X-ray selected clusters with spectroscopically measured redshifts. To avoid antenna beam effects, we bring all the maps to the same resolution. We use a CMB template to subtract the cosmological signal while preserving the Thermal Sunyaev-Zeldovich (TSZ) anisotropies; next, we remove galactic foreground emissions around each cluster and we mask out all known point sources. If the CMB black-body temperature scales with redshift as $T(z)=T_0(1+z)^{1-\\alpha}$, we constrain deviations of adiabatic evolution to be $\\alpha=-0.007\\pm 0.013$, consistent with the temperature-redshift relation of the standard cosmological model. This result could suffer from a potential bias associated with the CMB template, that we quantify it to be less than $-0.02$, but is free from those biases associated with using TSZ selected ...

  8. High-energy x-ray detection of G359.89–0.08 (SGR A–E): magnetic flux tube emission powered by cosmic rays?

    DEFF Research Database (Denmark)

    Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.

    2014-01-01

    We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89–0.08 (Sgr A–E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ∼50 keV during a NuSTAR Galactic center...

  9. Academic Training: The cosmic microwave background - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    ACADEMIC TRAINING LECTURE REGULAR PROGRAMME 14, 15, 16, 17 and 18 June From 11:00 hrs to 12:00 hrs - Main Auditorium bldg. 500 The cosmic microwave background M. Zaldarriaga / Harvard University, USA The Cosmic Microwave Background has become an indispensable tool for cosmology. The measurement of its frequency spectrum firmly established the Hot Big Bang model of the Universe. Measurements of anisotropies in its temperature and its degree of polarization provide the earliest snapshot we have of the universe, giving us information about its state at the epoch of hydrogen recombination approximately 300,000 after the Big Bang. The anisotropies can be used to constrain many of the parameters in the cosmological model, such as the mean density of baryons and dark matter as well as the curvature of the Universe. In this lectures I will review the physics of the temperature and polarization anisotropies. I will discuss the mechanisms that lead to the anisotropies and how cosmological parameters can be inferr...

  10. Cosmic backgrounds of relic gravitons and their absolute normalization

    Science.gov (United States)

    Giovannini, Massimo

    2014-11-01

    Provided the consistency relations are not violated, the recent BICEP2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid or from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequency uncertainties. The limits on the cosmic graviton backgrounds coming from wide-band interferometers (such as LIGO/Virgo, LISA and BBO/DECIGO) together with a more accurate scrutiny of the tensor B-mode polarization at low frequencies will set direct bounds on the post-inflationary evolution and on other unconventional completions of the standard lore.

  11. The X-ray emission from the knots in 3C 120

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    3C 120 is a Seyfert galaxy with a well detected X-ray jet.We investigate the X-ray emission of its five jet knots and fit their spectral energy distributions(SEDs) from the radio to the X-ray bands with a single-zone lepton model.We find that the SEDs of knots k7,s2,and s3 can be explained by synchrotron radiation,and the X-rays are the simple extension of the radio-optical emission component,but that of the inner knot k4 requires the IC/CMB model,in which the X-rays are due to the inverse Compton scattering of the cosmic microwave background photons by relativistic electrons in the jet with a beaming factor δ-14.The outer knot k25 is resolved into a three-part sub-structure.It is shown that the fitting of the X-rays from this knot with the IC/CMB model needs an extraordinary beaming factor δ-15-25 for a jet at the kpc scale.If the X-rays of knot k25 are produced by synchrotron radiation similar to k7,s2,and s3,they may be contributed by a relativistic electron population whose radiations in other wavelengths are not detected.

  12. Cosmic Shear of the Microwave Background: The Curl Diagnostic

    CERN Document Server

    Cooray, A R; Caldwell, R R; Cooray, Asantha; Kamionkowski, Marc; Caldwell, Robert R.

    2005-01-01

    Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is to deflect the primary temperature and polarization signal to slightly different locations on the sky. Deflections due to density fluctuations, gradient-type for the gradient of the projected gravitational potential, give a direct measure of the mass distribution. Curl-type deflections can be induced by, for example, a primordial background of gravitational waves from inflation or by second-order effects related to lensing by density perturbations. Whereas gradient-type deflections are expected to dominate, we show that curl-type deflections can provide a useful test of systematics and serve to indicate the presence of confusing secondary and foreground non-Gaussian signals.

  13. Charting the New Frontier of the Cosmic Microwave Background Polarization

    CERN Document Server

    Bouchet, F R; Camus, P; Désert, F X; Piat, M; Ponthieu, N; Camus, Ph.

    2005-01-01

    The anisotropies of the cosmic microwave background are a gold mine for cosmology and fundamental physics. ESA's Planck satellite should soon extract all information from the temperature vein but will be limited concerning the measurement of the degree of polarization of the anisotropies. This polarization information allows new independent tests of the standard cosmological paradigm, improves knowledge of cosmological parameters and last but not least is the best window available for constraining the physics of the very early universe, particularly the expected background of primordial gravitational waves. But exploiting this vein will be a challenge, since the sensitivity required is {\\em at least} 10 times better than what Planck might achieve at best, with the necessary matching level of control of all systematics effects, both instrumental and astrophysical (foregrounds). We here recall the cosmological context and the case for CMB polarization studies. We also briefly introduce the SAMPAN project, a des...

  14. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Richard Conn [Henry A. Rowland Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Murthy, Jayant [Indian Institute of Astrophysics, Bengaluru (India); Overduin, James; Tyler, Joshua, E-mail: henry@jhu.edu, E-mail: jmurthy@yahoo.com, E-mail: joverduin@towson.edu, E-mail: 97tyler@cardinalmail.cua.edu [Department of Physics, Astronomy and Geosciences, Towson University, Towson, MD 21252 (United States)

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a ''second population'' of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 μm emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such ''smaller'' grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Lyα—it could be that our ''second component'' of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  15. X-Ray

    Science.gov (United States)

    ... You may be allowed to remain with your child during the test. If you remain in the room during the X-ray exposure, you'll likely be asked to wear a lead apron to shield you from unnecessary exposure. After the X-ray ...

  16. Dental x-rays

    Science.gov (United States)

    ... X-rays are a form of high energy electromagnetic radiation. The x-rays penetrate the body to form ... for detecting cavities, unless the decay is very advanced and deep. Many ... The amount of radiation given off during the procedure is less than ...

  17. Suzaku X-ray Observations of the Fermi Bubbles' Edges

    CERN Document Server

    Kataoka, J; Totani, T; Sofue, Y; Stawarz, L; Takahashi, Y; Takeuchi, Y; Tsunemi, H; Kimura, M; Takei, Y; Cheung, C C; Inoue, Y; Nakamori, T

    2013-01-01

    We present Suzaku X-ray observations along two edge regions of the Fermi Bubbles, with eight ~20 ksec pointings across the northern part of the North Polar Spur (NPS) surrounding the north bubble and six across the southernmost edge of the south bubble. After removing compact X-ray features, diffuse X-ray emission is clearly detected and is well reproduced by a three-component spectral model consisting of unabsorbed thermal emission (temperature kT ~0.1 keV from the Local Bubble (LB), absorbed kT ~0.3 keV thermal emission related to the NPS and/or Galactic Halo (GH), and a power-law component at a level consistent with the cosmic X-ray background. The emission measure (EM) of the 0.3 keV plasma decreases by ~50% toward the inner regions of the north-east bubble, with no accompanying temperature change. However, such a jump in the EM is not clearly seen in the south bubble data. While it is unclear if the NPS originates from a nearby supernova remnant or is related to previous activity within/around the Galact...

  18. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complicate the estimation of the soft X-ray luminosity function and cosmological evolution of AGN.

  19. X-ray Polarimetry

    Science.gov (United States)

    Kallman, T.

    In spite of the recent advances in X-ray instrumentation, polarimetry remains an area which has been virtually unexplored in the last 20 years. The scientific motivation to study polarization has increased during this time: emission models designed to repro- duce X-ray spectra can be tested using polarization, and polarization detected in other wavelength bands makes clear predictions as to the X-ray polarization. Polarization remains the only way to infer geometrical properties of sources which are too small to be spatially resolved. At the same time, there has been recent progress in instrumen- tation which is likely to allow searches for X-ray polarization at levels significantly below what was possible for early detectors. In this talk I will review the history of X-ray polarimetry, discuss some experimental techniques and the scientific problems which can be addressed by future experiments.

  20. The cosmic background radiation circa {nu}2K

    Energy Technology Data Exchange (ETDEWEB)

    Bond, J. Richard; Pogosyan, Dmitry; Prunet, Simon

    2000-01-01

    We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima CMB balloon experiments. The inflation-based cosmic structure formation paradigm we have been operating with for two decades has never been in better shape. Here we primarily focus on a simplified inflation parameter set, {l_brace}{omega}{sub b}, {omega}{sub cdm}, {omega}{sub tot}, {omega}{sub {lambda}}, n{sub s}, {tau}{sub C}, {sigma}{sub 8}{r_brace}. Combining all of the current CMB+LSS data points to the remarkable conclusion that the local Hubble patch we can access has little mean curvature ({omega}{sub tot} = 1.08 {+-} 0.06) and the initial fluctuations were nearly scale invariant (n{sub s} 1.03 {+-} 0.08), both predictions of (non-baroque) inflation theory. The baryon density is found to be slightly larger than that preferred by independent Big Bang Nucleosynthesis estimates ({omega}{sub b}-{omega}{sub b}h{sup 2} 0.030 {+-} 0.005 cf. 0.019 {+-} 0.002). The CDM density is in the expected range ({omega}{sub cdm} 0.17{+-}0.02). Even stranger is the CMB+LSS evidence that the density of the universe is dominated by unclustered energy akin to the cosmological constant ({omega}{sub {lambda}} = 0.66 {+-} 0.06), at the same level as that inferred from high redshift supernova observations. We also sketch the CMB+LSS implications for massive neutrinos.

  1. The deep look onto the hard X-ray sky: The Swift - INTEGRAL X-ray (SIX) survey

    CERN Document Server

    Bottacini, Eugenio; Greiner, Jochen

    2012-01-01

    The super-massive black-holes in the centers of Active Galactic Nuclei (AGNs) are surrounded by obscuring matter that can block the nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently flying hard X-ray (above 15 keV) missions. At these energies only ~1% of the intensity of the Cosmic X-ray Background (CXB) can be resolved into point-like sources that are AGNs. In this work we address the question of the undetected sources contributing to the CXB with a very sensitive and new hard X-ray survey: the SIX survey that is obtained with the new approach of combining the Swift/BAT and INTEGRAL/IBIS X-ray observations. We merge the observations of both missions. This enhances the exposure time and reduces systematic uncertainties. As a result we obtain a new survey over a wide sky area of 6200 deg^2 that is more sensitive than the surveys of Swift/BAT or INTEGRAL/IBIS alone. Our sample comprises 113 sources: 86 AGNs (Seyfert-like and blaza...

  2. Re-evaluation of the Cosmic Microwave Background (CMB)

    Science.gov (United States)

    Haynes, R.

    2009-12-01

    The cosmic microwave background (CMB) has an almost perfect black-body spectrum, with polarization. These characteristics are inconsistent with the Standard Big Bang (SBB) model. An almost perfect spectrum can arise only from a surface of last scattering which is an almost perfect black-body. Thermodynamically, this is matter in thermal equilibrium, absorbing almost 100% of incident radiation and re-emitting it as black-body radiation. By definition, a perfect black-body is matter at zero kelvin, and cold matter better approaches this perfection. SBB theory describes the CMB as originating from a hydrogen-helium plasma, condensing at a temperature of about 3,000 K. Such a surface would exhibit a continuous radiation spectrum, not unlike that of the sun, which is shown to have a spectrum similar, but not identical to, a black-body spectrum. An imperfect spectrum, even stretched 1100 fold as in the SBB model, remains an imperfect spectrum. Also, a plasma would not support the orientation required to impart polarization to the CMB. A better explanation of the observational evidence is possible if one views the observable universe as part of, and originating from, a much larger structure. Here we propose a defined physical description for such a model. It is shown how a "cosmic fabric" of spin-oriented atomic hydrogen, at zero kelvin, surrounding a matter-depletion zone and the observable universe, would produce the CMB observations. The cosmic fabric would be a perfect black-body and subsequently re-emit an almost perfect black-body spectrum. The radiation would be almost perfectly isotropic, imposed by the spherical distribution of the surface of last scattering, and spin-oriented hydrogen would impart the observed polarization. This geometry also obviates the so-called "horizon problem" of the SBB, why the CMB radiation is essentially isotropic when coming from points of origin with no apparent causal contact. This problem was supposedly "solved" with the

  3. X-ray crystallography

    Science.gov (United States)

    2001-01-01

    X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

  4. Heating the intergalactic medium by X-rays from population III binaries in high-redshift galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hao; Norman, Michael L. [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Ahn, Kyungjin [Department of Earth Science Education, Chosun University, Gwangju 501-759 (Korea, Republic of); Wise, John H. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332 (United States); O' Shea, Brian W., E-mail: hxu@ucsd.edu, E-mail: mlnorman@ucsd.edu, E-mail: kjahn@chosun.ac.kr, E-mail: jwise@gatech.edu, E-mail: oshea@msu.edu [Lyman Briggs College and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2014-08-20

    Due to their long mean free path, X-rays are expected to have an important impact on cosmic reionization by heating and ionizing the intergalactic medium (IGM) on large scales, especially after simulations have suggested that Population III (Pop III) stars may form in pairs at redshifts as high as 20-30. We use the Pop III distribution and evolution from a self-consistent cosmological radiation hydrodynamic simulation of the formation of the first galaxies and a simple Pop III X-ray binary model to estimate their X-ray output in a high-density region larger than 100 comoving (Mpc){sup 3}. We then combine three different methods—ray tracing, a one-zone model, and X-ray background modeling—to investigate the X-ray propagation, intensity distribution, and long-term effects on the IGM thermal and ionization state. The efficiency and morphology of photoheating and photoionization are dependent on the photon energies. The sub-kiloelectronvolt X-rays only impact the IGM near the sources, while the kiloelectronvolt photons contribute significantly to the X-ray background and heat and ionize the IGM smoothly. The X-rays just below 1 keV are most efficient in heating and ionizing the IGM. We find that the IGM might be heated to over 100 K by z = 10 and the high-density source region might reach 10{sup 4} K, limited by atomic hydrogen cooling. This may be important for predicting the 21 cm neutral hydrogen signals. On the other hand, the free electrons from X-ray ionizations are not enough to contribute significantly to the optical depth of the cosmic microwave background to the Thomson scattering.

  5. High Precision Cosmology with the Cosmic Background Radiation

    Science.gov (United States)

    Farhang, Marzieh

    In this thesis we investigate the two cosmic epochs of inflation and recombination, through their imprints on the temperature and polarization anisotropies of the cosmic microwave background radiation. To probe the early universe we develop a map-based maximum-likelihood estimator to measure the amplitude of inflation-induced gravity waves, parametrized by r, from the cosmic microwave background (CMB) polarization maps. Being optimal by construction, the estimator avoids E-B mixing, a possible source of contamination in the tiny B-mode detection, the target of many current and near future CMB experiments. We explore the leakage from the E- to the B-mode of polarization by using this estimator to study the linear response of the B-mode signal at different scales to variations in the E- mode power. Similarly, for various observational cases, we probe the dependence of r measurement on the signal from different scales of E and B polarization. The estimator is used to make forecasts for Spider-like and Planck-like experimental specifications and to investigate the sky-coverage optimization of the Spider-like case. We compare the forecast errors on r to the results from a similar multipole-based estimator which, by ignoring the mode-mixing, sets a lower limit on the achievable error on r. We find that an experiment with Spider-like specifications with fsky ˜ 0:02--0:2 could place a 2sigma r ≈ 0:014 bound (˜ 95% CL), which rises to 0:02 with an ℓ-dependent foreground residual left over from an assumed efficient component separation. For the Planck-like survey, a Galaxy-masked ( fsky = 0:75) sky would give 2sigmar ≈ 0:015, rising to ≈ 0:05 with the foreground residuals. We also use a novel information-based framework to compare how different generations of CMB experiments reveal information about the early universe, through their measurements of r. We also probe the epoch of recombination by investigating possible fluctuations in the free electron fraction Xe

  6. Cosmic microwave background constraints on secret interactions among sterile neutrinos

    Science.gov (United States)

    Forastieri, Francesco; Lattanzi, Massimiliano; Mangano, Gianpiero; Mirizzi, Alessandro; Natoli, Paolo; Saviano, Ninetta

    2017-07-01

    Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with MX ll MW), and characterized by a gauge coupling gX, have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data on Cosmic Microwave Background anisotropies, and measurements of baryon acoustic oscillations (BAO). We consistently include the effect of secret interactions on cosmological perturbations, namely the increased density and pressure fluctuations in the neutrino fluid, and still find a severe tension between the secret interaction framework and cosmology. In fact, taking into account neutrino scattering via secret interactions, we derive our own mass bound on sterile neutrinos and find (at 95 % CL) ms relatively large coupling gX~ 10-1, previously indicated as a possible solution to the small scale dark matter problem.

  7. Cosmic backgrounds of relic gravitons and their absolute normalization

    CERN Document Server

    Giovannini, Massimo

    2014-01-01

    Provided the consistency relations are not violated, the recent Bicep2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid of from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequencies...

  8. Cold+hot dark matter and the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, S. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Gates, E. [Department of Astronomy & Astrophysics, Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637-1433 (United States)]|[NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Stebbins, A. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)

    1996-08-01

    We examine the cosmic microwave background power spectrum for adiabatic models with a massive neutrino component. We present the results of a detailed numerical evolution of cold+hot dark matter (CHDM) models and compare these results with the standard cold dark matter (CDM) spectrum. The difference is of order 5{percent}{endash}10{percent} for 400{lt}{ital l}{lt}1000 for currently popular CHDM models. Using semi-analytic approximations, we also discuss the relevant physics involved. Finally, we remark on the ability of future experiments to differentiate between these models. An all-sky experiment with a beam size smaller than 30{prime} can distinguish between CHDM and CDM if other cosmological parameters are known. Even allowing other parameters to vary, it may be possible to distinguish CDM from CHDM. {copyright} {ital 1996 The American Astronomical Society.}

  9. The Cosmic Infrared Background Experiment (CIBER): The Low Resolution Spectrometer

    CERN Document Server

    Tsumura, K; Battle, J; Bock, J; Brown, S; Cooray, A; Hristov, V; Keating, B; Kim, M G; Lee, D H; Levenson, L R; Lykke, K; Mason, P; Matsumoto, T; Matsuura, S; Murata, K; Nam, U W; Renbarger, T; Smith, A; Sullivan, I; Suzuki, K; Wada, T; Zemcov, M

    2011-01-01

    Absolute spectrophotometric measurements of diffuse radiation at 1 \\mu m to 2 \\mu m are crucial to our understanding of the radiative content of the Universe from nucleosynthesis since the epoch of reionization, the composition and structure of the Zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment (CIBER) is a \\lambda / \\Delta \\lambda \\sim 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 \\mu m < \\lambda < 2.1 \\mu m. This paper presents the optical, mechanical and electronic design of the LRS, as well as the ground testing, characterization and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding a...

  10. South Pole submillimeter isotropy measurements of the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Dragovan, M. (Joseph Henry Laboratory, Princeton University, Princeton, NJ 08544 (USA)); Platt, S.R.; Pernic, R.J. (The University of Chicago, Yerkes Observatory, Williams Bay, WI 531191 (USA)); Stark, A.A. (AT T Bell Laboratories, Holmdel, NJ 07733 (USA))

    1990-01-15

    Observations were made from the United States Amundsen-Scott South Pole Station during the austral summer of 1988--89 to search for spatial anisotropy in the submillimeter Cosmic Microwave Background. Three 30{prime}{times}30{prime} regions of the sky were observed at 350 {mu}m, 450 {mu}m, and 600 {mu}m with the University of Chicago 32-Channel Submillimeter Photometer and a 1.2-meter off-axis parabolic telescope, designed and constructed at AT T Bell Laboratories. Reimaging optics gave each of the 32 bolometers in the array a 5-arc minute field of view. The search is sensitive to fluctuations on all angular scales between 5- and 30-arc minutes.

  11. The small scale power asymmetry in the cosmic microwave background

    CERN Document Server

    Flender, Samuel

    2013-01-01

    We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l=601-2048, with a naive statistical significance of 6.5 sigma. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations. After correcting for all of these effects, the significance level drops to ~1 sigma, i.e., there is no anomalous intrinsic asymmetry in the small angular scales. Using this null result, we derive a constraint on a potential dipolar modulation amplitude, A(k)<0.0045 on the ~10 Mpc-scale, at 95% C.L. This new constraint must be satisfied by any theoretical model attempting to explain the hemispherical asymmetry at large angular scales.

  12. Local Signal Impedes the Definition of the Cosmic Infrared Background

    Science.gov (United States)

    Kelsall, Thomas

    2010-01-01

    It was noted (ApJ 508, 44, 1998) when developing a COBE/DIRBE-data-based model for the infrared (IR) signal from the interplanetary dust cloud (IPD) that there were clear evidences of unexpected time-variable wavelength-dependent signals in all the ten DIRBE bands (1.2 to 240 μm). The amplitudes of these signals range in magnitude from the order of one-half to a few percent of the respective-wavelength IPD signal. This presentation provides selected details on the nature of these signals as regards their wavelength-dependent periodicities, time-variable amplitudes, and complex spatial configurations. Particular attention is devoted to describing the consequences imposed by these signals which impede the observational determination of and/or the setting of limits on the cosmic IR background.

  13. Far Infrared Spectrometry of the Cosmic Background Radiation

    Science.gov (United States)

    Mather, J. C.

    1974-01-01

    I describe two experiments to measure the cosmic background radiation near 1 mm wavelength. The first was a ground-based search for spectral lines, made with a Fabry-Perot interferometer and an InSb detector. The second is a measurement of the spectrum from 3 to 18 cm{sup -1}, made with a balloon-borne Fourier transform spectrometer. It is a polarizing Michelson interferometer, cooled in liquid helium, and operated with a germanium bolometer. I give the theory of operation, construction details, and experimental results. The first experiment was successfully completed but the second suffered equipment malfunction on its first flight. I describe the theory of Fourier transformations and give a new understanding of convolutional phase correction computations. I discuss for infrared bolometer calibration procedures, and tabulate test results on nine detectors. I describe methods of improving bolometer sensitivity with immersion optics and with conductive film blackening.

  14. Systematic errors in cosmic microwave background polarization measurements

    CERN Document Server

    O'Dea, D; Johnson, B R; Dea, Daniel O'; Challinor, Anthony

    2006-01-01

    We investigate the impact of instrumental systematic errors on the potential of cosmic microwave background polarization experiments targeting primordial B-modes. To do so, we introduce spin-weighted Muller matrix-valued fields describing the linear response of the imperfect optical system and receiver, and give a careful discussion of the behaviour of the induced systematic effects under rotation of the instrument. We give the correspondence between the matrix components and known optical and receiver imperfections, and compare the likely performance of pseudo-correlation receivers and those that modulate the polarization with a half-wave plate. The latter is shown to have the significant advantage of not coupling the total intensity into polarization for perfect optics, but potential effects like optical distortions that may be introduced by the quasi-optical wave plate warrant further investigation. A fast method for tolerancing time-invariant systematic effects is presented, which propagates errors throug...

  15. Large Scale Anomalies of the Cosmic Microwave Background with Planck

    DEFF Research Database (Denmark)

    Frejsel, Anne Mette

    This thesis focuses on the large scale anomalies of the Cosmic Microwave Background (CMB) and their possible origins. The investigations consist of two main parts. The first part is on statistical tests of the CMB, and the consistency of both maps and power spectrum. We find that the Planck data...... is very consistent, while the WMAP 9 year release appears more contaminated by non-CMB residuals than the 7 year release. The second part is concerned with the anomalies of the CMB from two approaches. One is based on an extended inflationary model as the origin of one specific large scale anomaly, namely....... Here we find evidence that the Planck CMB maps contain residual radiation in the loop areas, which can be linked to some of the large scale CMB anomalies: the point-parity asymmetry, the alignment of quadrupole and octupole and the dipolemodulation....

  16. Accelerating Cosmic Microwave Background map-making procedure through preconditioning

    CERN Document Server

    Szydlarski, Mikolaj; Stompor, Radek

    2014-01-01

    Estimation of the sky signal from sequences of time ordered data is one of the key steps in Cosmic Microwave Background (CMB) data analysis, commonly referred to as the map-making problem. Some of the most popular and general methods proposed for this problem involve solving generalised least squares (GLS) equations with non-diagonal noise weights given by a block-diagonal matrix with Toeplitz blocks. In this work we study new map-making solvers potentially suitable for applications to the largest anticipated data sets. They are based on iterative conjugate gradient (CG) approaches enhanced with novel, parallel, two-level preconditioners. We apply the proposed solvers to examples of simulated non-polarised and polarised CMB observations, and a set of idealised scanning strategies with sky coverage ranging from nearly a full sky down to small sky patches. We discuss in detail their implementation for massively parallel computational platforms and their performance for a broad range of parameters characterising...

  17. Phase Correlations in Cosmic Microwave Background Temperature Maps

    CERN Document Server

    Coles, P; Earl, J; Wright, D; Coles, Peter; Dineen, Patrick; Earl, John; Wright, Dean

    2003-01-01

    We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of these modes, we look instead at their phases. In particular, we present a simple measure of phase correlation that can be diagnostic of departures from the standard assumption that primordial density fluctuations constitute a statistically homogeneous and isotropic Gaussian random field, which should possess phases that are uniformly random on the unit circle. The method we discuss checks for the uniformity of the distribution of phase angles using a non-parametric descriptor based on the use order statistics, which is known as Kuiper's statistic. The particular advantage of the method we present is that, when coupled to the judicious use of Monte Carlo simulations, it can deliver very interesting results from small data samples. In particular, it is useful for studying the properties of spherical harmonics at low l ...

  18. Cosmic microwave background science at commercial airline altitudes

    Science.gov (United States)

    Feeney, Stephen M.; Gudmundsson, Jon E.; Peiris, Hiranya V.; Verde, Licia; Errard, Josquin

    2017-07-01

    Obtaining high-sensitivity measurements of degree-scale cosmic microwave background (CMB) polarization is the most direct path to detecting primordial gravitational waves. Robustly recovering any primordial signal from the dominant foreground emission will require high-fidelity observations at multiple frequencies, with excellent control of systematics. We explore the potential for a new platform for CMB observations, the Airlander 10 hybrid air vehicle, to perform this task. We show that the Airlander 10 platform, operating at commercial airline altitudes, is well suited to mapping frequencies above 220 GHz, which are critical for cleaning CMB maps of dust emission. Optimizing the distribution of detectors across frequencies, we forecast the ability of Airlander 10 to clean foregrounds of varying complexity as a function of altitude, demonstrating its complementarity with both existing (Planck) and ongoing (C-BASS) foreground observations. This novel platform could play a key role in defining our ultimate view of the polarized microwave sky.

  19. Cosmic Microwave Background Science at Commercial Airline Altitudes

    CERN Document Server

    Feeney, Stephen M; Peiris, Hiranya V; Verde, Licia; Errard, Josquin

    2016-01-01

    Obtaining high-sensitivity measurements of degree-scale cosmic microwave background (CMB) polarization is the most direct path to detecting primordial gravitational waves. Robustly recovering any primordial signal from the dominant foreground emission will require high-fidelity observations at multiple frequencies, with excellent control of systematics. We explore the potential for a new platform for CMB observations, the Airlander 10 hybrid air vehicle, to perform this task. We show that the Airlander 10 platform, operating at commercial airline altitudes, is well-suited to mapping frequencies above 220 GHz, which are critical for cleaning CMB maps of dust emission. Optimizing the distribution of detectors across frequencies, we forecast the ability of Airlander 10 to clean foregrounds of varying complexity as a function of altitude, demonstrating its complementarity with both existing (Planck) and ongoing (C-BASS) foreground observations. This novel platform could play a key role in defining our ultimate vi...

  20. Spectator fields and their imprints on the Cosmic Microwave Background

    CERN Document Server

    Wang, Lingfei

    2016-01-01

    When a subdominant light scalar field ends slow roll during inflation, but well after the Hubble exit of the pivot scales, it may determine the cosmological perturbations. This thesis investigates how such a scalar field, the spectator, may leave its impact on the Cosmic Microwave Background (CMB) radiation and be consequently constrained. We first introduce the observables of the CMB, namely the power spectrum $P_\\zeta$, spectral index $n_s$ and its running $dn_s/d\\ln k$, the non-Gaussianities $f_{NL}$, $g_{NL}$ and $\\tau_{NL}$, and the lack of isocurvature and polarization modes. Based on these studies, we derive the cosmological predictions for the spectator scenario, revealing its consistency with the CMB for inflection point potentials, hyperbolic tangent potentials, and those with a sudden phase transition. In the end, we utilize the spectator scenario to explain the CMB power asymmetry, with a brief tachyonic fast-roll phase.

  1. Extracting cosmic microwave background polarisation from satellite astrophysical maps

    CERN Document Server

    Baccigalupi, C; De Zotti, G; Smoot, G F; Burigana, C; Maino, D; Bedini, L; Salerno, E

    2002-01-01

    We present the application of the Fast Independent Component Analysis technique for blind component separation to polarised astrophysical emission. We study how the Cosmic Microwave Background (CMB) polarised signal, consisting of $E$ and $B$ modes, can be extracted from maps affected by substantial contamination from diffuse Galactic foregrounds and instrumental noise. We perform the analysis of all sky maps simulated accordingly to the nominal performances of the Low Frequency Instrument (LFI) aboard the Planck satellite; the sky signal is modeled as a superposition of CMB, generated by a Gaussian, nearly scale invariant cosmological perturbation spectrum, and the existing simulated polarisation templates of Galactic synchrotron. Our results indicate that the angular power spectrum of CMB $E$ modes can be recovered on all scales up to $\\ell\\simeq 1000$, corresponding to the fourth acoustic oscillation, while $B$ modes can be detected, up to their turnover at $\\ell\\simeq 100$ if cosmological tensor amplitude...

  2. Searching for Faraday rotation in cosmic microwave background polarization

    Science.gov (United States)

    Ruiz-Granados, B.; Battaner, E.; Florido, E.

    2016-08-01

    We use the Wilkinson Microwave Anisotropy Probe (WMAP) 9th-year foreground reduced data at 33, 41 and 61 GHz to derive a Faraday rotation at map and at angular power spectrum levels taking into account their observational errors. A processing mask provided by WMAP is used to avoid contamination from the disc of our Galaxy and local spurs. We have found a Faraday rotation component at both, map and power spectrum levels. The lack of correlation of the Faraday rotation with Galactic Faraday rotation, synchrotron and dust polarization from our Galaxy or with cosmic microwave background anisotropies or lensing suggests that it could be originated at reionization (ℓ ≲ 12). Even if the detected Faraday rotation signal is weak, the present study could contribute to establish magnetic fields strengths of B0 ˜ 10-8 G at reionization.

  3. Large Scale Anomalies of the Cosmic Microwave Background with Planck

    DEFF Research Database (Denmark)

    Frejsel, Anne Mette

    This thesis focuses on the large scale anomalies of the Cosmic Microwave Background (CMB) and their possible origins. The investigations consist of two main parts. The first part is on statistical tests of the CMB, and the consistency of both maps and power spectrum. We find that the Planck data...... is very consistent, while the WMAP 9 year release appears more contaminated by non-CMB residuals than the 7 year release. The second part is concerned with the anomalies of the CMB from two approaches. One is based on an extended inflationary model as the origin of one specific large scale anomaly, namely....... Here we find evidence that the Planck CMB maps contain residual radiation in the loop areas, which can be linked to some of the large scale CMB anomalies: the point-parity asymmetry, the alignment of quadrupole and octupole and the dipolemodulation....

  4. The Origin of the UCSD X-ray Astronomy Program - A Personal Perspective

    Science.gov (United States)

    Peterson, Laurence E.

    2013-01-01

    I was a graduate student in the late 1950’s at the University of Minnesota in the Cosmic Ray Group under Prof. John R. Winckler. He had a project monitoring Cosmic ray time variations from an extensive series of balloon flights using simple detectors during the International Geophysical Year 1957-58. During the 20 March 1958 flight, a short 18 sec. burst of high energy radiation was observed simultaneously with a class II Solar flare. From the ratio of the Geiger counter rate to the energy loss in the ionization chamber, it was determined this radiation was likely hard X-rays or low-energy gamma rays and not energetic particles. Further analysis using information from other concurrent observations indicated the X-rays were likely due to Bremsstrahlung from energetic electrons accelerated in the solar flare magnetic field; these same electrons produced radio emissions. This first detection of extra-terrestrial X- or gamma rays showed the importance of non-thermal processes in Astrophysical phenomena. Winckler and I were interested by the possibility of non-solar hard X-rays. While completing my thesis on a Cosmic ray topic, I initiated a balloon program to develop more sensitive collimated low-background scintillation counters. This led to a proposal to the newly formed NASA to place an exploratory instrument on the 1st Orbiting Solar Observatory launched 7 March 1962. In August that year, I assumed a tenure-track position at UCSD; the data analysis of OSO-1 and the balloon program were transferred to UCSD to initiate the X-ray Astronomy program. The discovery of Cosmic X-ray sources in the 1-10 Kev range on a rocket flight in June 1962 by Giacconi and colleagues gave impetus to the UCSD activities. It seemed evident cosmic X-ray sources could be detected above 20 Kev using high-flying balloons. Early results included measurements of the 50 million K gas in SCO X-1, and the X-ray continuum from the Crab Nebula characterized by a power-law dN/dE ~ E-2.2. The

  5. Another look at distortions of the Cosmic Microwave Background spectrum

    Science.gov (United States)

    De Zotti, G.; Negrello, M.; Castex, G.; Lapi, A.; Bonato, M.

    2016-03-01

    We review aspects of Cosmic Microwave Background (CMB) spectral distortions which do not appear to have been fully explored in the literature. In particular, implications of recent evidences of heating of the intergalactic medium (IGM) by feedback from active galactic nuclei are investigated. Taking also into account the IGM heating associated to structure formation, we argue that values of the y parameter of several × 10-6, i.e. a factor of a few below the COBE/FIRAS upper limit, are to be expected. The Compton scattering by the re-ionized plasma also re-processes primordial distortions, adding a y-type contribution. Hence no pure Bose-Einstein-like distortions are to be expected. An assessment of Galactic and extragalactic foregrounds, taking into account the latest results from the Planck satellite as well as the contributions from the strong CII and CO lines from star-forming galaxies, demonstrates that a foreground subtraction accurate enough to fully exploit the PIXIE sensitivity will be extremely challenging. Motivated by this fact we also discuss methods to detect spectral distortions not requiring absolute measurements and show that accurate determinations of the frequency spectrum of the CMB dipole amplitude may substantially improve over COBE/FIRAS limits on distortion parameters. Such improvements may be at reach of next generation CMB anisotropy experiments. The estimated amplitude of the Cosmic Infrared Background (CIB) dipole might be detectable by careful analyses of Planck maps at the highest frequencies. Thus Planck might provide interesting constraints on the CIB intensity, currently known with a simeq 30% uncertainty.

  6. Supernova remnants: the X-ray perspective

    NARCIS (Netherlands)

    Vink, J.

    2012-01-01

    Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects. And i

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very small ... X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is a noninvasive medical ...

  8. Tracking Down the Source Population Responsible for the Unresolved Cosmic 6-8 keV Background

    CERN Document Server

    Xue, Y Q; Brandt, W N; Luo, B; Alexander, D M; Bauer, F E; Comastri, A; Fabian, A C; Gilli, R; Lehmer, B D; Schneider, D P; Vignali, C; Young, M

    2012-01-01

    Using the 4 Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray undetected galaxies that dominates the unresolved ~ 20-25% of the 6-8 keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South HST z-band imaging of the central 6'-radius area of the 4 Ms CDF-S. The stacked 6-8 keV detection is significant at the 3.9 sigma level, but the stacked emission was not detected in the 4-6 keV band which indicates the existence of an underlying population of highly obscured active galactic nuclei (AGNs). Further examinations of these 6845 galaxies indicate that the galaxies on the top of the blue cloud and with redshifts of 1 ~1E10 M_sun) galaxies. We discuss constraints upon this underlying AGN population, supporting evidence for relatively low-mass galaxies hosting highly obscured AGNs, and prospects for further boosting the stacked signal.

  9. The cosmic infrared background experiment (CIBER): instrumentation and first results

    Science.gov (United States)

    Zemcov, M.; Battle, J.; Bock, J.; Cooray, A.; Hristov, V.; Keating, B.; Lee, D. H.; Levenson, L.; Mason, P.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.

    2010-07-01

    Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z ~ 6; the wavelength of these photons has been redshifted by (1 + z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background ExpeRiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodiacal light foreground with a high resolution spectrometer in each of our six science fields. The scientific motivation for CIBER and details of its first and second flight instrumentation will be discussed. First flight results on the color of the zodiacal light around 1 μm and plans for the future will also be presented.

  10. Bone x-ray

    Science.gov (United States)

    ... or broken bone Bone tumors Degenerative bone conditions Osteomyelitis (inflammation of the bone caused by an infection) ... Multiple myeloma Osgood-Schlatter disease Osteogenesis imperfecta Osteomalacia Osteomyelitis Paget disease of the bone Rickets X-ray ...

  11. Hand x-ray

    Science.gov (United States)

    ... include fractures, bone tumors , degenerative bone conditions, and osteomyelitis (inflammation of the bone caused by an infection). ... chap 46. Read More Bone tumor Broken bone Osteomyelitis X-ray Review Date 9/8/2014 Updated ...

  12. Pelvis x-ray

    Science.gov (United States)

    X-ray - pelvis ... Tumors Degenerative conditions of bones in the hips, pelvis, and upper legs ... hip joint Tumors of the bones of the pelvis Sacroiliitis (inflammation of the area where the sacrum ...

  13. Chest X-Ray

    Medline Plus

    Full Text Available ... and use a very small dose of ionizing radiation to produce pictures of the inside of the ... x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs ...

  14. Chest X-Ray

    Medline Plus

    Full Text Available ... Index A-Z Spotlight October is National Breast Cancer Awareness Month Recently posted: Medical Imaging Costs Magnetoencephalography ( ... of lung conditions such as pneumonia, emphysema and cancer. A chest x-ray requires no special preparation. ...

  15. Chest X-Ray

    Medline Plus

    Full Text Available ... chest x-ray is used to evaluate the lungs, heart and chest wall and may be used ... diagnose and monitor treatment for a variety of lung conditions such as pneumonia, emphysema and cancer. A ...

  16. X-ray - skeleton

    Science.gov (United States)

    ... x-ray particles pass through the body. A computer or special film records the images. Structures that ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  17. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  18. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  19. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  20. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  1. Chest X-Ray

    Medline Plus

    Full Text Available ... CT Angiography Video: Myelography Video: CT of the Heart Video: Radioiodine I-131 Therapy Radiology and You ... x-ray is used to evaluate the lungs, heart and chest wall and may be used to ...

  2. Characterization of Construction Material Properties through Gamma Spectroscopy, X-ray Fluorescence, and Hyper-spectral Imagery for Background Correction Applications in Nuclear Detection

    Science.gov (United States)

    2014-03-27

    spectroscopy, 2) X-ray fluorescence (XRF), and 3) hyper-spectral imagery. Gamma-spectroscopy focuses on the presence of potassium as well as uranium and...each material. Each materials hyper-spectral characteristics are compared to chemical composition and radioactive properties to determine if any...of bundling a variety of sensors onto a small number of vehicles. A MISTI vehicle carries a ten by ten sodium iodide detector array with a coded

  3. Bone X-Ray (Radiography)

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    Full Text Available ... holds the x-ray film or image recording plate . Sometimes the x-ray is taken with the ... an x-ray film holder or image recording plate is placed beneath the patient. top of page ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the limitations of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) ... diagnosis and disease management. top of page How is the procedure performed? The technologist, an individual specially ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... holds the x-ray film or image recording plate . Sometimes the x-ray is taken with the ... an x-ray film holder or image recording plate is placed beneath the patient. top of page ...

  6. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... that might interfere with the x-ray images. Women should always inform their physician and x-ray ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

  8. The Cosmic Infrared Background Experiment (CIBER): The Low Resolution Spectrometer

    Science.gov (United States)

    Tsumura, K.; Arai, T.; Battle, J.; Bock, J.; Brown, S.; Cooray, A.; Hristov, V.; Keating, B.; Kim, M. G.; Lee, D. H.; Levenson, L. R.; Lykke, K.; Mason, P.; Matsumoto, T.; Matsuura, S.; Murata, K.; Nam, U. W.; Renbarger, T.; Smith, A.; Sullivan, I.; Suzuki, K.; Wada, T.; Zemcov, M.

    2013-08-01

    Absolute spectrophotometric measurements of diffuse radiation at 1 μm to 2 μm are crucial to our understanding of the radiative content of the universe from nucleosynthesis since the epoch of reionization, the composition and structure of the zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment is a λ/Δλ ~ 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 μm <λ < 2.1 μm. This paper presents the optical, mechanical, and electronic design of the LRS, as well as the ground testing, characterization, and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding and control of sources of systematic error for absolute photometry of the near-infrared extragalactic background light.

  9. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): THE LOW RESOLUTION SPECTROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, K.; Arai, T.; Matsumoto, T.; Matsuura, S.; Murata, K. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronoutical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Battle, J.; Bock, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Brown, S.; Lykke, K.; Smith, A. [Optical Technology Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899 (United States); Cooray, A. [Center for Cosmology, University of California, Irvine, Irvine, CA 92697 (United States); Hristov, V.; Levenson, L. R.; Mason, P. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H.; Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Sullivan, I., E-mail: tsumura@ir.isas.jaxa.jp [Department of Physics, The University of Washington, Seattle, WA 98195 (United States); and others

    2013-08-15

    Absolute spectrophotometric measurements of diffuse radiation at 1 {mu}m to 2 {mu}m are crucial to our understanding of the radiative content of the universe from nucleosynthesis since the epoch of reionization, the composition and structure of the zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment is a {lambda}/{Delta}{lambda} {approx} 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 {mu}m <{lambda} < 2.1 {mu}m. This paper presents the optical, mechanical, and electronic design of the LRS, as well as the ground testing, characterization, and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding and control of sources of systematic error for absolute photometry of the near-infrared extragalactic background light.

  10. Radiometer system to map the cosmic background radiation

    Science.gov (United States)

    Gorenstein, M. V.; Muller, R. A.; Smoot, G. F.; Tyson, J. A.

    1978-01-01

    A 33-GHz airborne radiometer system has been developed to map large angular scale variations in the temperature of the 3 K cosmic background radiation. A ferrite circulator switches a room-temperature mixer between two antennas pointing 60 deg apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of plus or minus 1 mK rms, or about 1 part in 3000 of 3 K. The apparatus is flown in a U-2 jet to 20 km altitude where 33-GHz thermal microwave emission from the atmosphere is at a low level. A second radiometer, tuned to 54 GHz near oxygen emission lines, monitors spurious signals from residual atmospheric radiation. The antennas, which have an extremely low side-lobe response of less than -65 dB past 60 deg, reject anisotropic radiation from the earth's surface. Periodic interchange of the antenna positions and reversal of the aircraft's flight direction cancel equipment-based imbalances. The system has been operated successfully in U-2 aircraft flown from NASA-Ames at Moffett Field, Calif.

  11. Sensitivity of the Fe Kα Compton shoulder to the geometry and variability of the X-ray illumination of cosmic objects

    Science.gov (United States)

    Odaka, Hirokazu; Yoneda, Hiroki; Takahashi, Tadayuki; Fabian, Andrew

    2016-11-01

    In an X-ray reflection spectrum, a tail-like spectral feature generated via Compton downscattering, known as a Compton shoulder (CS), appears at the low-energy side of the iron Kα line. Despite its great diagnostic potential, its use as a spectral probe of the reflector has been seriously limited due to observational difficulties and modelling complexities. We revisit the basic nature of the CS by systematic investigation into its dependence on spatial and temporal parameters. The calculations are performed by Monte Carlo simulations for sphere and slab geometries. The dependence is obtained in a two-dimensional space of column density and metal abundance, demonstrating that the CS solves parameter degeneration between them which was seen in conventional spectral analysis using photoelectric absorption and fluorescence lines. Unlike the iron line, the CS does not suffer from any observational dependence on the spectral hardness. The CS profile is highly dependent on the inclination angle of the slab geometry unless the slab is Compton-thick, and the time evolution of the CS is shown to be useful to constrain temporal information on the source if the intrinsic radiation is variable. We also discuss how atomic binding of the scattering electrons in cold matter blurs the CS profile, finding that the effect is practically similar to thermal broadening in a plasma with a moderate temperature of ˜5 eV. Spectral diagnostics using the CS is demonstrated with grating data of X-ray binary GX 301-2, and will be available in future with high-resolution spectra of active galactic nuclei obtained by microcalorimeters.

  12. Detection of Cosmic Microwave Background Structure in a Second Field with the Cosmic Anisotropy Telescope

    CERN Document Server

    Baker, J C; Hobson, M P; Jones, M E; Kneissl, R; Lasenby, A N; O'Sullivan, C M M; Pooley, G G; Rocha, G; Saunders, R; Scott, P F; Waldram, E M; Baker, Joanne C.; Grainge, Keith; Jones, Michael E.; Pooley, Guy; Saunders, Richard

    1999-01-01

    We describe observations at frequencies near 15 GHz of the second 2x2 degree field imaged with the Cambridge Cosmic Anisotropy Telescope (CAT). After the removal of discrete radio sources, structure is detected in the images on characteristic scales of about half a degree, corresponding to spherical harmonic multipoles in the approximate range l= 330--680. A Bayesian analysis confirms that the signal arises predominantly from the cosmic microwave background (CMB) radiation for multipoles in the lower half of this range; the average broad-band power in a bin with centroid l=422 (theta = 51') is estimated to be Delta_T/T=2.1^{+0.4}_{-0.5} x 10^{-5}. For multipoles centred on l=615 (theta =35'), we find contamination from Galactic emission is significant, and constrain the CMB contribution to the measured power in this bin to be Delta_T/T <2.0 x 10^{-5} (1-sigma upper limit). These new results are consistent with the first detection made by CAT in a completely different area of sky. Together with data from ot...

  13. Litmus Test for Cosmic Hemispherical Asymmetry in the Cosmic Microwave Background B-Mode Polarization.

    Science.gov (United States)

    Mukherjee, Suvodip; Souradeep, Tarun

    2016-06-01

    Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements. We demonstrate that weak lensing of the CMB due to scalar perturbations produces a corresponding SI violation in B modes of CMB polarization at smaller angular scales. The measurability of this phenomenon depends upon the scales (l range) over which power asymmetry is present. Power asymmetry, which is restricted only to l<64 in the temperature field, cannot lead to any significant observable effect from this new window. However, this effect can put an independent bound on the spatial range of scales of hemispherical asymmetry present in the scalar sector.

  14. Preheating of the early universe by radiation from high-mass X-ray binaries

    Science.gov (United States)

    Sazonov, S. Yu.; Khabibullin, I. I.

    2017-04-01

    Using a reliablymeasured intrinsic (i.e., corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star formation rate, we estimate the preheating of the early Universe by soft X-rays from such systems. We find that X-ray irradiation, mainly executed by ultraluminous and supersoft ultraluminous X-ray sources with luminosity L X > 1039 erg s-1, could significantly heat ( T > T CMB, where T CMB is the temperature of the cosmic microwave background) the intergalactic medium by z 10 if the specific X-ray emissivity of the young stellar population in the early Universe was an order of magnitude higher than at the present epoch (which is possible due to the low metallicity of the first galaxies) and the soft X-ray emission from HMXBs did not suffer strong absorption within their galaxies. This makes it possible to observe the 21 cm line of neutral hydrogen in emission from redshifts z < 10.

  15. X-Ray Absorption with Transmission X-Ray Microscopes

    NARCIS (Netherlands)

    de Groot, F.M.F.

    2016-01-01

    In this section we focus on the use of transmission X-ray microscopy (TXM) to measure the XAS spectra. In the last decade a range of soft X-ray and hard X-ray TXM microscopes have been developed, allowing the measurement of XAS spectra with 10–100 nm resolution. In the hard X-ray range the TXM

  16. X-ray Pulsars

    CERN Document Server

    Walter, Roland

    2016-01-01

    X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or by instabilities in accretion discs. Wind driven flows are highly unstable close to neutron stars and responsible for X-ray variability by factors $10^3$ on time scale of hours. Disk driven flows feature slower state transitions and quasi periodic oscillations related to orbital motion and precession or resonance. On shorter time scales, and closer to the surface of the neutron star, X-ray variability is dominated by the interactions of the accreting flow with the spinning magnetosphere. When the pulsar magnetic field is large, the flow is confined in a relatively narrow accretion column, whose geometrical properties drive the observed X-ray emission. In low magnetized systems, an increasing accretion rate allows the ignition of powerful explosive thermonuclear burning at t...

  17. The Anisotropy of the Microwave Background to l = 3500 Mosaic Observations with the Cosmic Background Imager

    CERN Document Server

    Pearson, T J; Readhead, A C S; Shepherd, M C; Sievers, J L; Udomprasert, P S; Cartwright, J K; Farmer, A J; Padin, S; Myers, S T; Bond, J R; Contaldi, C R; Pen, U L; Prunet, S; Pogosyan, D; Carlstrom, J E; Kovács, J; Leitch, E M; Pryke, C L; Halverson, N W; Holzapfel, W L; Altamirano, P; Bronfman, L; Casassus, S; May, J; Joy, M

    2003-01-01

    Using the Cosmic Background Imager, a 13-element interferometer array operating in the 26-36 GHz frequency band, we have observed 40 sq deg of sky in three pairs of fields, each ~ 145 x 165 arcmin, using overlapping pointings (mosaicing). We present images and power spectra of the cosmic microwave background radiation in these mosaic fields. We remove ground radiation and other low-level contaminating signals by differencing matched observations of the fields in each pair. The primary foreground contamination is due to point sources (radio galaxies and quasars). We have subtracted the strongest sources from the data using higher-resolution measurements, and we have projected out the response to other sources of known position in the power-spectrum analysis. The images show features on scales ~ 6 - 15 arcmin, corresponding to masses ~ (5 - 80)*10^{14} Msun at the surface of last scattering, which are likely to be the seeds of clusters of galaxies. The power spectrum estimates have a resolution Delta-l = 200 an...

  18. Cross correlation of Cosmic Microwave background and Weak Lensing

    CERN Document Server

    Lee, Seokcheon

    2015-01-01

    The integrated Sachs-Wolfe (ISW) effect and its non-linear extension Rees-Sciama (RS) effect provide us the information of the time evolution of gravitational potential. The cross-correlation between the cosmic microwave background (CMB) and the large scale structure (LSS) is known as a promising way to extract the ISW (RS) effect. It is known that the RS effect shows the unique behavior by changing the anti-correlated cross correlation between the CMB and the mass tracer into the positively correlated cross correlation compared to the linear ISW effect. We show that the dependence of this flipping scale of the cross-correlation between RS and weak lensing on dark energy models. However, there exists the degeneracy between DE and $\\Omega_{\\rm{m}0}$ which might be broken by redshift dependent observables. The cross-correlation between the momentum field and the density field might be served as the better observable to be used for this purpose.

  19. Cosmic microwave background polarization and temperature anisotropies from symmetric structures

    CERN Document Server

    Baccigalupi, C

    1999-01-01

    I explore the undulatory properties of the cosmic microwave background (CMB) physics. I consider the cases of spherical and cylindrical symmetry of the perturbation source, or seed. Such structures could have been left by high energy symmetries breaking in the early universe. I give suitable analytic expressions for the polarization and temperature linear perturbations from this kind of seeds and I show how to get their appearence on the CMB sky. This treatment highlights the undulatory properties of the CMB. I show with numerical examples how the polarization and temperature perturbations propagate beyond the size of their seeds, reaching the CMB sound horizon at the time considered. Just like the waves from a pebble thrown in a pond, the CMB anisotropy appears as a series of temperature and polarization waves surrounding the seed, extending on the scale of the CMB sound horizon at decoupling, roughly $1^{o}$ in the sky. Each wave is characterized by its own value of the CMB perturbation, with the same mean ...

  20. Reionization and the cosmic microwave background in an open universe

    Science.gov (United States)

    Persi, Fred M.

    1995-01-01

    If the universe was reionized at high reshift (z greater than or approximately equal to 30) or never recombined, then photon-electron scattering can erase fluctuations in the cosmic microwave background at scales less than or approximately equal to 1 deg. Peculiar motion at the surface of last scattering will then have given rise to new anisotropy at the 1 min level through the Vishniac effect. Here the observed fluctuations in galaxy counts are extrapolated to high redshifts using linear theory, and the expected anisotropy is computed. The predicted level of anisotropies is a function of Omega(sub 0) and the ratio of the density in ionized baryons to the critical density and is shown to depend strongly on the large- and small-scale power. It is not possible to make general statements about the viability of all reionized models based on current observations, but it is possible to rule out specific models for structure formation, particularly those with high baryonic content or small-scale power. The induced fluctuations are shown to scale with cosmological parameters and optical depth.

  1. Multiple Lensing of the Cosmic Microwave Background anisotropies

    CERN Document Server

    Calabrese, Matteo; Fabbian, Giulio; Baldi, Marco; Baccigalupi, Carlo

    2014-01-01

    We study the gravitational lensing effect on the Cosmic Microwave Background (CMB) anisotropies performing a ray-tracing of the primordial CMB photons through intervening large-scale structures (LSS) distribution predicted by N-Body numerical simulations with a particular focus on the precise recovery of the lens-induced polarized counterpart of the source plane. We apply both a multiple plane ray-tracing and an effective deflection approach based on the Born approximation to deflect the CMB photons trajectories through the simulated lightcone. We discuss the results obtained with both these methods together with the impact of LSS non-linear evolution on the CMB temperature and polarization power spectra. We compare our results with semi-analytical approximations implemented in Boltzmann codes like, e.g., CAMB. We show that, with our current N-body setup, the predicted lensing power is recovered with good accuracy in a wide range of multipoles while excess power with respect to semi-analytic prescriptions is ...

  2. Detection of Polarization in the Cosmic Microwave Background using DASI

    CERN Document Server

    Kovács, J M; Pryke, C L; Carlstrom, J E; Halverson, N W; Holzapfel, W L

    2002-01-01

    We report the detection of polarized anisotropy in the Cosmic Microwave Background radiation with the Degree Angular Scale Interferometer (DASI), located at the Amundsen-Scott South Pole research station. Observations in all four Stokes parameters were obtained within two 3.4 FWHM fields separated by one hour in Right Ascension. The fields were selected from the subset of fields observed with DASI in 2000 in which no point sources were detected and are located in regions of low Galactic synchrotron and dust emission. The temperature angular power spectrum is consistent with previous measurements and its measured frequency spectral index is -0.01 (-0.16 -- 0.14 at 68% confidence), where 0 corresponds to a 2.73 K Planck spectrum. The power spectrum of the detected polarization is consistent with theoretical predictions based on the interpretation of CMB anisotropy as arising from primordial scalar adiabatic fluctuations. Specifically, E-mode polarization is detected at high confidence (4.9 sigma). Assuming a sh...

  3. DASI Three-Year Cosmic Microwave Background Polarization Results

    CERN Document Server

    Leitch, E M; Halverson, N W; Carlstrom, J E; Pryke, C L; Smith, M W E; Leitch, Erik M.

    2004-01-01

    We present the analysis of the complete 3-year data set obtained with the Degree Angular Scale Interferometer (DASI) polarization experiment, operating from the Amundsen-Scott South Pole research station. Additional data obtained at the end of the 2002 Austral winter and throughout the 2003 season were added to the data from which the first detection of polarization of the cosmic microwave background radiation was reported. The analysis of the combined data supports, with increased statistical power, all of the conclusions drawn from the initial data set. In particular, the detection of E-mode polarization is increased to 6.3 sigma confidence level, TE cross-polarization is detected at 2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit well below the level of the detected E-mode polarization. The results are in excellent agreement with the predictions of the cosmological model that has emerged from CMB temperature measurements. The analysis also demonstrates that contamination of ...

  4. Cosmic microwave background power spectrum estimation with the destriping technique

    Science.gov (United States)

    Poutanen, T.; Maino, D.; Kurki-Suonio, H.; Keihänen, E.; Hivon, E.

    2004-09-01

    Extraction of the cosmic microwave background (CMB) angular power spectrum is a challenging task for current and future CMB experiments due to the large data sets involved. Here we describe an implementation of Monte Carlo apodized spherical transform estimator (MASTER) described in Hivon et al., which exploits the destriping technique as a map-making method. In this method a noise estimate based on destriped noise-only Monte Carlo (MC) simulations is subtracted from the pseudo-angular power spectrum. As a working case we use realistic simulations of the Planck low-frequency instrument (LFI). We found that the effect of destriping on a pure sky signal is minimal and requires no correction. Instead we found an effect related to the distribution of detector pointings, which affects the high-l part of the power spectrum. We correct for this by subtracting a `signal bias' estimated by MC simulations. We also give analytical estimates for this signal bias. Our method is fast and accurate enough (the estimator is unbiased and errors are close to theoretical expectations for maximal accuracy) to estimate the CMB angular power spectra for current and future CMB space missions. This study is related to Planck LFI activities.

  5. Cosmic microwave background power spectrum estimation with the destriping technique

    CERN Document Server

    Poutanen, T; Kurki-Suonio, H; Keihanen, E; Hivon, E

    2004-01-01

    Extraction of the CMB (Cosmic Microwave Background) angular power spectrum is a challenging task for current and future CMB experiments due to the large data sets involved. Here we describe an implementation of MASTER (Monte carlo Apodised Spherical Transform EstimatoR) which exploits the destriping technique as a map-making method. In this method a noise estimate based on destriped noise-only MC (Monte Carlo) simulations is subtracted from the pseudo angular power spectrum. As a working case we use realistic simulations of the PLANCK LFI (Low Frequency Instrument). We found that the effect of destriping on a pure sky signal is minimal and requires no correction. Instead we found an effect related to the distribution of detector pointings, which affects the high multipole part of the power spectrum. We correct for this by subtracting a ``signal bias'' estimated by MC simulations. We also give analytical estimates for this signal bias. Our method is fast and accurate enough (the estimator is un-biased and erro...

  6. Non-linear evolution of the cosmic neutrino background

    CERN Document Server

    Villaescusa-Navarro, Francisco; Peña-Garay, Carlos; Viel, Matteo

    2012-01-01

    We investigate the non-linear evolution of the relic cosmic neutrino background by running large box-size, high resolution N-body simulations. Our set of simulations explore the properties of neutrinos in a reference $\\Lambda$CDM model with total neutrino masses between 0.05-0.60 eV in cold dark matter haloes of mass $10^{11}-10^{15}$ $h^{-1}$M$_{\\odot}$, over a redshift range $z=0-2$. We compute the halo mass function and show that it is reasonably well fitted by the Sheth-Tormen formula. More importantly, we focus on the CDM and neutrino properties of the density and peculiar velocity fields in the cosmological volume, inside and in the outskirts of virialized haloes. The dynamical state of the neutrino particles depends strongly on their momentum: whereas neutrinos in the low velocity tail behave similarly to CDM particles, neutrinos in the high velocity tail are not affected by the clustering of the underlying CDM component. We find that the neutrino (linear) unperturbed momentum distribution is modified ...

  7. Delensing the CMB with the Cosmic Infrared Background

    CERN Document Server

    Sherwin, Blake D

    2015-01-01

    As confusion with lensing B-modes begins to limit experiments that search for primordial B-mode polarization, robust methods for delensing the CMB polarization sky are becoming increasingly important. We investigate in detail the possibility of delensing the CMB with the cosmic infrared background (CIB), emission from dusty star-forming galaxies that is an excellent tracer of the CMB lensing signal, in order to improve constraints on the tensor-to-scalar ratio $r$. We find that the maps of the CIB, such as current Planck satellite maps at 545 GHz, can be used to remove more than half of the lensing B-mode power. Calculating optimal combinations of different large-scale-structure tracers for delensing, we find that co-adding CIB data and external arcminute-resolution CMB lensing reconstruction can lead to significant additional improvements in delensing performance. We investigate whether measurement uncertainty in the CIB spectra will degrade the delensing performance if no model of the CIB spectra is assumed...

  8. The information content of cosmic microwave background anisotropies

    CERN Document Server

    Scott, Douglas; Narimani, Ali; Ma, Yin-Zhe

    2016-01-01

    The cosmic microwave background (CMB) contains perturbations that are close to Gaussian and isotropic. This means that its information content, in the sense of the ability to constrain cosmological models, is closely related to the number of modes probed in CMB power spectra. Rather than making forecasts for specific experimental setups, here we take a more pedagogical approach and ask how much information we can extract from the CMB if we are only limited by sample variance. We show that, compared with temperature measurements, the addition of E-mode polarization doubles the number of modes available out to a fixed maximum multipole, provided that all of the TT, TE, and EE power spectra are measured. However, the situation in terms of constraints on particular parameters is more complicated, as we illustrate. We also discuss the enhancements in information that can come from adding B-mode polarization and gravitational lensing. We show how well one could ever determine the basic cosmological parameters from ...

  9. A framework for testing isotropy with the cosmic microwave background

    CERN Document Server

    Saadeh, Daniela; Pontzen, Andrew; Peiris, Hiranya V; McEwen, Jason D

    2016-01-01

    We present a new framework for testing the isotropy of the Universe using cosmic microwave background data, building on the nested-sampling ANICOSMO code. Uniquely, we are able to constrain the scalar, vector and tensor degrees of freedom alike; previous studies only considered the vector mode (linked to vorticity). We employ Bianchi type VII$_h$ cosmologies to model the anisotropic Universe, from which other types may be obtained by taking suitable limits. In a separate development, we improve the statistical analysis by including the effect of Bianchi power in the high-$\\ell$, as well as the low-$\\ell$, likelihood. To understand the effect of all these changes, we apply our new techniques to WMAP data. We find no evidence for anisotropy, constraining shear in the vector mode to $(\\sigma_V/H)_0 < 1.7 \\times 10^{-10}$ (95% CL). For the first time, we place limits on the tensor mode; unlike other modes, the tensor shear can grow from a near-isotropic early Universe. The limit on this type of shear is $(\\sig...

  10. Reionization during the dark ages from a cosmic axion background

    CERN Document Server

    Evoli, Carmelo; Mirizzi, Alessandro; Montanino, Daniele

    2016-01-01

    Recently it has been pointed out that a cosmic background of relativistic axion-like particles (ALPs) would be produced by the primordial decays of heavy fields in the post-inflation epoch, contributing to the extra-radiation content in the Universe today. Primordial magnetic fields would trigger conversions of these ALPs into sub-MeV photons during the dark ages. This photon flux would produce an early reionization of the Universe, leaving a significant imprint on the total optical depth to recombination $\\tau$. Using the current measurement of $\\tau$ and the limit on the extra-radiation content $\\Delta N_{\\rm eff} $ by the Planck experiment we put a strong bound on the ALP-photon conversions. Namely we obtain upper limits on the product of the photon-ALP coupling constant $g_{a\\gamma}$ times the magnetic field strength $B$ down to $g_{a\\gamma} B \\gtrsim 6 \\times 10^{-18} \\textrm{GeV}^{-1} \\textrm{nG} $ for ultralight ALPs.

  11. Planck Visualization Project: Seeing and Hearing the Cosmic Microwave Background

    Science.gov (United States)

    van der Veen, J.

    2010-08-01

    The Planck Mission, launched May 14, 2009, will measure the sky over nine frequency channels, with temperature sensitivity of a few microKelvin, and angular resolution of up to 5 arc minutes. Planck is expected to provide the data needed to set tight constraints on cosmological parameters, study the ionization history of the Universe, probe the dynamics of the inflationary era, and test fundamental physics. The Planck Education and Public Outreach collaborators at NASA's Jet Propulsion Laboratory, the University of California, Santa Barbara and Purdue University are preparing a variety of materials to present the science goals of the Planck Mission to the public. Two products currently under development are an interactive simulation of the mission which can be run in a virtual reality environment, and an interactive presentation on interpreting the power spectrum of the Cosmic Microwave Background with music. In this paper we present a brief overview of CMB research and the Planck Mission, and discuss how to explain, to non-technical audiences, the theory of how we derive information about the early universe from the power spectrum of the CMB by using the physics of music.

  12. A circular polarimeter for the Cosmic Microwave Background

    CERN Document Server

    Giovannini, Massimo

    2010-01-01

    A primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution of the temperature fluctuations as well as the equations for the linear polarization. The observed values of the temperature and polarization angular power spectra are used to infer constraints on the amplitude and on the spectral slope of the primordial V-mode. Prior to photon decoupling magnetic fields play the role of polarimeters insofar as they unveil the circular dichroism by coupling the V-mode power spectrum to the remaining brightness perturbations. Conversely, for angular scales ranging between 4 deg and 10 deg the joined bounds on the magnitude of circular polarization and on the magnetic field intensity suggest that direct limits on the V-mode power spectrum in the range of 0.01 mK could directly rule ou...

  13. A Cosmic Microwave Background Radiation Polarimeter Using Superconducting Bearings

    CERN Document Server

    Hanany, S; Johnson, B; Jones, T; Hull, J R; Ma, K B

    2003-01-01

    Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured the coefficient of friction as a function of several parameters including temperature between 15 and 80 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and ambient pressure between 10^{-7} and 1 torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission.

  14. A framework for testing isotropy with the cosmic microwave background

    Science.gov (United States)

    Saadeh, Daniela; Feeney, Stephen M.; Pontzen, Andrew; Peiris, Hiranya V.; McEwen, Jason D.

    2016-10-01

    We present a new framework for testing the isotropy of the Universe using cosmic microwave background data, building on the nested-sampling ANICOSMO code. Uniquely, we are able to constrain the scalar, vector and tensor degrees of freedom alike; previous studies only considered the vector mode (linked to vorticity). We employ Bianchi type VIIh cosmologies to model the anisotropic Universe, from which other types may be obtained by taking suitable limits. In a separate development, we improve the statistical analysis by including the effect of Bianchi power in the high-ℓ, as well as the low-ℓ, likelihood. To understand the effect of all these changes, we apply our new techniques to Wilkinson Microwave Anisotropy Probe data. We find no evidence for anisotropy, constraining shear in the vector mode to (σV/H)0 < 1.7 × 10-10 (95 per cent confidence level). For the first time, we place limits on the tensor mode; unlike other modes, the tensor shear can grow from a near-isotropic early Universe. The limit on this type of shear is (σT, reg/H)0 < 2.4 × 10- 7 (95 per cent confidence level).

  15. Reconstruction of lensing from the cosmic microwave background polarization

    CERN Document Server

    Hirata, C M; Hirata, Christopher M.; Seljak, Uros

    2003-01-01

    Gravitational lensing of the cosmic microwave background (CMB) polarization field has been recognized as a potentially valuable probe of the cosmological density field. We apply likelihood-based techniques to the problem of lensing of CMB polarization and show that if the B-mode polarization is mapped, then likelihood-based techniques allow significantly better lensing reconstruction than is possible using the previous quadratic estimator approach. With this method the ultimate limit to lensing reconstruction is not set by the lensed CMB power spectrum. Second-order corrections are known to produce a curl component of the lensing deflection field that cannot be described by a potential; we show that this does not significantly affect the reconstruction at noise levels greater than 0.25 microK arcmin. The reduction of the mean squared error in the lensing reconstruction relative to the quadratic method can be as much as a factor of two at noise levels of 1.4 microK arcmin to a factor of ten at 0.25 microK arcm...

  16. Cosmic birefringence fluctuations and cosmic microwave background B-mode polarization

    Directory of Open Access Journals (Sweden)

    Seokcheon Lee

    2015-06-01

    Full Text Available Recently, BICEP2 measurements of the cosmic microwave background (CMB B-mode polarization has indicated the presence of primordial gravitational waves at degree angular scales, inferring the tensor-to-scalar ratio of r=0.2 and a running scalar spectral index, provided that dust contamination is low. In this Letter, we show that the existence of the fluctuations of cosmological birefringence can give rise to CMB B-mode polarization that fits BICEP2 data with r<0.11 and no running of the scalar spectral index. When dust contribution is taken into account, we derive an upper limit on the cosmological birefringence, Aβ2<0.0075, where A is the amplitude of birefringence fluctuations that couple to electromagnetism with a coupling strength β.

  17. Cosmic sculpture: a new way to visualise the cosmic microwave background

    Science.gov (United States)

    Clements, D. L.; Sato, S.; Portela Fonseca, A.

    2017-01-01

    3D printing presents an attractive alternative to visual representation of physical datasets such as astronomical images that can be used for research, outreach or teaching purposes, and is especially relevant to people with a visual disability. We here report the use of 3D printing technology to produce a representation of the all-sky cosmic microwave background (CMB) intensity anisotropy maps produced by the Planck mission. The success of this work in representing key features of the CMB is discussed as is the potential of this approach for representing other astrophysical data sets. 3D printing such datasets represents a highly complementary approach to the usual 2D projections used in teaching and outreach work, and can also form the basis of undergraduate projects. The CAD files used to produce the models discussed in this paper are made available.

  18. Cosmic Sculpture: A new way to visualise the Cosmic Microwave Background

    CERN Document Server

    Clements, D L; Fonseca, A Portela

    2016-01-01

    3D printing presents an attractive alternative to visual representation of physical datasets such as astronomical images that can be used for research, outreach or teaching purposes, and is especially relevant to people with a visual disability. We here report the use of 3D printing technology to produce a representation of the all-sky Cosmic Microwave Background (CMB) intensity anisotropy maps produced by the Planck mission. The success of this work in representing key features of the CMB is discussed as is the potential of this approach for representing other astrophysical data sets. 3D printing such datasets represents a highly complementary approach to the usual 2D projections used in teaching and outreach work, and can also form the basis of undergraduate projects. The CAD files used to produce the models discussed in this paper are made available.

  19. Background research in support of the new grant proposal: Research consortium for X-ray topography on line X-19 at NSLS

    Science.gov (United States)

    Bilello, J. C.

    1983-11-01

    The status of the construction and installation of components of the synchrotron topography station is reported as well as progress in the development of hardware for interfacing and software for interactively controlling the 13 motors which automate the facility. Research focuses on the problem of X-ray optics and on techniques for applying topography to materials science. There is colaboration with other researchers in studying the nature of brittle fracture of refractory metals and in interpreting contact in the vicinity of crack tips.

  20. Near-IR Extragalactic Background Results from the Cosmic Infrared Background Experiment (CIBER)

    Science.gov (United States)

    Zemcov, Michael B.; CIBER

    2016-01-01

    The near IR extragalactic background light (EBL) encodes the integrated light production over cosmic history, so represents the total emission from all galaxies along the line of sight up to ancient first-light objects present during the epoch of reionization (EOR). This EOR emission necessarily comprises part of the background, and indeed a minimum level is required to supply enough photons to ionize the intergalactic medium, corresponding to an EBL brightness less than 1 nW m^-2 sr^-1, about one tenth of the integrated galactic light (IGL). In addition to emission from these IGL and EOR populations, low surface brightness tidal streams of stars stripped by gravitational interactions during galaxy formation at low redshifts, called intrahalo light (IHL), may also contribute a significant fraction of the EBL. Models for these components can be constrained both through direct photometric measurements, as well as the new technique of EBL anisotropy intensity mapping that takes advantage of the fact that the Zodiacal Light is spatially smooth while distant populations produce anisotropies with distinct spatial and spectral characteristics. This talk will present recent results from the Cosmic Infrared Background Experiment (CIBER), a sounding rocket borne payload designed to measure both the fluctuations and direct photometric emission of the extra-galactic background light. The anisotropy of the near-IR EBL suggests the presence of a bright component approximately as bright as the IGL component near 1 micron which we interpret as the aggregate emission from low-redshift IHL. New direct photometric measurements from CIBER's low resolution spectrometer will also be discussed.

  1. Early results from the Cosmic Background Explorer (COBE)

    Energy Technology Data Exchange (ETDEWEB)

    Mather, J.C.; Hauser, M.G.; Bennett, C.L.; Boggess, N.W.; Cheng, E.S.; Eplee, R.E. Jr.; Freudenreich, H.T.; Isaacman, R.B.; Kelsall, T.; Lisse, C.M.; Moseley, S.H. Jr.; Shafer, R.A.; Silverberg, R.F.; Spiesman, W.J.; Toller, G.N.; Weiland, J.L. (Laboratory for Astronomy and Solar Physics, Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)); Gulkis, S.; Jansssen, M. (Jet Propulsion Laboratory, MS 169-506, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)); Lubin, P.M. (UCSB Department of Physics, Goleta, California 93106 (United States)); Meyer, S.S.; Weiss, R. (Room 20F-001, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Murdock, T.L. (General Research Corporation, 5 Cherry Hill Drive, Suite 220, Danvers, Massachusetts 01923 (United States)); Smoot, G.F. (Lawrence Berkeley Laboratory, 50-232, University of California, Berkeley, California 94720 (United States)); Wilkinson, D.T. (Dep

    1992-01-10

    The Cosmic Background Explorer, launched November 18, 1989, has nearly completed its first full mapping of the sky with all three of its instruments: a Far Infrared Absolute Spectrophotometer (FIRAS) covering 0.1 to 10 mm, a set of Differential Microwave Radiometers (DMR) operating at 3.3, 5.7, and 9.6 mm, and a Diffuse Infrared Background Experiment (DIRBE) spanning 1 to 300 {mu}m in ten bands. A preliminary map of the sky derived from DIRBE data is presented. Initial cosmological implications include: a limit on the Comptonization {ital y} parameter of 10{sup {minus}3}, on the chemical potential {mu} parameter of 10{sup {minus}2}, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy has the spectrum expected from a Doppler shift of a blackbody. There are no significant anisotropies in the microwave sky detected, other than from our own galaxy and a cos {theta} dipole anisotropy whose amplitude and direction agree with previous data. At shorter wavelengths, the sky spectrum and anisotropies are dominated by emission from local' sources of emission within our Galaxy and Solar System. Preliminary comparison of {ital IRAS} and {ital DIRBE} sky brightnesses toward the ecliptic poles shows the {ital IRAS} values to be significantly higher than found by {ital DIRBE} at 100 {mu}m. We suggest the presence of gain and zero-point errors in the {ital IRAS} total brightness data. The spacecraft, instrument designs, and data reduction methods are described.

  2. Sensitivity of the Fe K-alpha Compton shoulder to the geometry and variability of the X-ray illumination of cosmic objects

    CERN Document Server

    Odaka, Hirokazu; Takahashi, Tadayuki; Fabian, Andrew

    2016-01-01

    In an X-ray reflection spectrum, a tail-like spectral feature generated via Compton down-scattering, known as a Compton shoulder (CS), appears at the low-energy side of the iron K$\\alpha$ line. Despite its great diagnostic potential, its use as a spectral probe of the reflector has been seriously limited due to observational difficulties and modelling complexities. We revisit the basic nature of the CS by systematic investigation into its dependence on spatial and temporal parameters. The calculations are performed by Monte-Carlo simulations for sphere and slab geometries. The dependence is obtained in a two-dimensional space of column density and metal abundance, demonstrating that the CS solves parameter degeneration between them which was seen in conventional spectral analysis using photoelectric absorption and fluorescence lines. Unlike the iron line, the CS does not suffer from any observational dependence on the spectral hardness. The CS profile is highly dependent on the inclination angle of the slab g...

  3. The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey I: Probing galaxy cluster magnetic fields with line of sight rotation measures

    CERN Document Server

    Boehringer, Hans; Kronberg, Philipp P

    2016-01-01

    To search for a signature of an intracluster magnetic field, we compare measurements of Faraday rotation of polarised extragalactic radio sources in the line of sight of galaxy clusters with those outside. We correlated a catalogue of 1383 rotation measures (RM) of extragalactic polarised radio sources with X-ray luminous galaxy clusters from the CLASSIX survey (combining REFLEX II and NORAS II). We compared the RM in the line of sight of clusters within their projected radii of r_500 with those outside and found a significant excess of the dispersion of the RM in the cluster regions. Since the observed RM is the result of Faraday rotation in several presumably uncorrelated magnetised cells of the intracluster medium, the observations correspond to quantities averaged over several magnetic field directions and strengths. Therefore the interesting quantity is the standard deviation of the RM for an ensemble of clusters. We found a standard deviation of the RM inside r_500 of about 120 +- 21 rad m^-2. This comp...

  4. X-Ray Protection

    Science.gov (United States)

    1955-01-01

    15,000. • When developed In Kodak liquid X-ray developer for 5 min at a temperature of 200 C. b Film sensitivities vary with photon energy by the...for example temporomandibular -joint exposures where a skin dose of 25 r or more may be obtained during a single exposure with 65 kvp, 1.5 mm aluminum...communication. W. J. Updegrave, Temporomandibular articulation-X-ray examina- tion, Dental Radiography and Photography 26, No. 3, 41 (1953). H. 0. Wyckoff, R. J

  5. X-ray Reflection

    Science.gov (United States)

    Fabian, A. C.; Ross, R. R.

    2010-12-01

    Material irradiated by X-rays produces backscattered radiation which is commonly known as the Reflection Spectrum. It consists of a structured continuum, due at high energies to the competition between photoelectric absorption and electron scattering enhanced at low energies by emission from the material itself, together with a complex line spectrum. We briefly review the history of X-ray reflection in astronomy and discuss various methods for computing the reflection spectrum from cold and ionized gas, illustrated with results from our own work reflionx. We discuss how the reflection spectrum can be used to obtain the geometry of the accretion flow, particularly the inner regions around black holes and neutron stars.

  6. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a very small dose of ... x-ray , is a two-dimensional (2-D) dental x-ray examination that captures the entire mouth ...

  7. Cosmic background radiation anisotropy in an open inflation, cold dark matter cosmogony

    Science.gov (United States)

    Kamionkowski, Marc; Ratra, Bharat; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At Omega(sub 0) is approximately 0.3-0.4, the Cosmic Background Explorer (COBE) normalized open model appears to be consistent with most observations.

  8. The imprint of the cosmic supermassive black hole growth history on the 21 cm background radiation

    CERN Document Server

    Tanaka, Takamitsu L; Perna, Rosalba

    2015-01-01

    The redshifted 21 cm transition line of hydrogen tracks the thermal evolution of the neutral intergalactic medium (IGM) at "cosmic dawn," during the emergence of the first luminous astrophysical objects (~100 Myr after the Big Bang) but before these objects ionized the IGM (~400-800 Myr after the Big Bang). Because X-rays, in particular, are likely to be the chief energy courier for heating the IGM, measurements of the 21 cm signature can be used to infer knowledge about the first astrophysical X-ray sources. Using analytic arguments and a numerical population synthesis algorithm, we argue that the progenitors of supermassive black holes (SMBHs) should be the dominant source of hard astrophysical X-rays---and thus the primary driver of IGM heating and the 21 cm signature---at redshifts $z 20$. An absence of such a signature in the forthcoming observational data would imply that SMBH formation occurred later (e.g. via so-called direct collapse scenarios), that it was not a common occurrence in early galaxies ...

  9. Imprint of DES superstructures on the cosmic microwave background

    Science.gov (United States)

    Kovács, A.; Sánchez, C.; García-Bellido, J.; Nadathur, S.; Crittenden, R.; Gruen, D.; Huterer, D.; Bacon, D.; Clampitt, J.; DeRose, J.; Dodelson, S.; Gaztañaga, E.; Jain, B.; Kirk, D.; Lahav, O.; Miquel, R.; Naidoo, K.; Peacock, J. A.; Soergel, B.; Whiteway, L.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M.; Tarle, G.; Thomas, D.; Walker, A. R.; DES Collaboration

    2017-03-01

    Small temperature anisotropies in the cosmic microwave background (CMB) can be sourced by density perturbations via the late-time integrated Sachs-Wolfe (ISW) effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey (DES) in a different footprint, and using a different superstructure finding strategy. We identified 52 large voids and 102 superclusters at redshifts 0.2 < z < 0.65. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with ΔTf ≈ -5.0 ± 3.7 μK and a hot imprint of superclusters ΔTf ≈ 5.1 ± 3.2 μK; this is ∼1.2σ higher than the expected |ΔTf| ≈ 0.6 μK imprint of such superstructures in Λ cold dark matter (ΛCDM). If we instead use an a posteriori selected filter size (R/Rv = 0.6), we can find a temperature decrement as large as ΔTf ≈ -9.8 ± 4.7 μK for voids, which is ∼2σ above ΛCDM expectations and is comparable to previous measurements made using Sloan Digital Sky Survey superstructure data.

  10. Imprint of DES superstructures on the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Kovács, A.; Sánchez, C.; García-Bellido, J.; Nadathur, S.; Crittenden, R.; Gruen, D.; Huterer, D.; Bacon, D.; Clampitt, J.; DeRose, J.; Dodelson, S.; Gaztañaga, E.; Jain, B.; Kirk, D.; Lahav, O.; Miquel, R.; Naidoo, K.; Peacock, J. A.; Soergel, B.; Whiteway, L.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Giannantonio, T.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M.; Tarle, G.; Thomas, D.; Walker, A. R.

    2016-11-17

    Small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshifts $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$ and a hot imprint of superclusters $\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$ ; this is $\\sim1.2\\sigma$ higher than the expected $|\\Delta T_{f}| \\approx 0.6~\\mu K$ imprint of such super-structures in $\\Lambda$CDM. If we instead use an a posteriori selected filter size ($R/R_{v}=0.6$), we can find a temperature decrement as large as $\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$ for voids, which is $\\sim2\\sigma$ above $\\Lambda$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.

  11. Measuring the cosmic microwave background polarization with POLARBEAR

    Science.gov (United States)

    Barron, Darcy; Polarbear Collaboration

    2015-01-01

    POLARBEAR is a cosmic microwave background (CMB) polarization experiment located in the Atacama desert in Chile. POLARBEAR-1 started observations in 2012, and in 2014, the POLARBEAR team published results from its first season of observations on a small fraction of the sky. These results include the first measurement of a non-zero B-mode polarization angular power spectrum, measured at sub-degree scales where the dominant signal is gravitational lensing of the CMB. We also published a measurement of the large-scale gravitational structure deflection power spectrum derived from CMB polarization alone, which demonstrates a powerful technique that can be used to measure nearly all of the gravitational structure in the universe. Improving these measurements requires precision characterization of the CMB polarization signal over large fractions of the sky, at multiple frequencies. To achieve these goals, POLARBEAR has begun expanding to include an additional two 3.5 meter telescopes with multi-chroic receivers, known as the Simons Array. Phased upgrades to receiver technology will improve sensitivity and capabilities, while continuing a deep survey of 80% of the sky. POLARBEAR-2 is the next receiver that will be installed in 2015 on a new telescope, with a larger area focal plane with dichroic pixels, with bands at 95 GHz and 150 GHz, and a total of 7,588 polarization sensitive antenna-coupled transition edge sensor bolometers. The focal plane is cooled to 250 milliKelvin, and the bolometers will be read-out by SQUID amplifiers with 40x frequency domain multiplexing. The array is designed to have a noise equivalent temperature of 5.7 μK√s.

  12. Chest X-Ray

    Medline Plus

    Full Text Available ... Therapy November 8 is the International Day of Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Chest X-ray Transcript Welcome to Radiology Info dot org! Hello, I’m Dr. Geoffrey ...

  13. Skewness in the Cosmic Microwave Background Anisotropy from Inflationary Gravity Wave Background

    CERN Document Server

    Bharadwaj, S; Souradeep, T; Bharadwaj, Somnath; Munshi, Dipak; Souradeep, Tarun

    1997-01-01

    In the context of inflationary scenarios, the observed large angle anisotropy of the Cosmic Microwave Background (CMB) temperature is believed to probe the primordial metric perturbations from inflation. Although the perturbations from inflation are expected to be gaussian random fields, there remains the possibility that nonlinear processes at later epochs induce ``secondary'' non-gaussian features in the corresponding CMB anisotropy maps. The non-gaussianity induced by nonlinear gravitational instability of scalar (density) perturbations has been investigated in existing literature. In this paper, we highlight another source of non-gaussianity arising out of higher order scattering of CMB photons off the metric perturbations. We provide a simple and elegant formalism for deriving the CMB temperature fluctuations arising due to the Sachs-Wolfe effect beyond the linear order. In particular, we derive the expression for the second order CMB temperature fluctuations. The multiple scattering effect pointed out i...

  14. Cosmic Infrared Background ExpeRiment (CIBER): A Probe of Extragalactic Background Light from Reionization

    CERN Document Server

    Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2009-01-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown on February 25th, 2009 and has one more planned flight in early 2010. We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times largerthan existing IR instruments on satellites, CIBER-II will carry out ...

  15. Cosmic Infrared Background ExpeRiment (CIBER): A probe of Extragalactic Background Light from reionization

    Science.gov (United States)

    Cooray, Asantha; Bock, Jamie; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2012-08-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown in February 2009 and July 2010 and four more flights are planned by 2014, including an upgrade (CIBER-II). We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times larger than existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

  16. Supernova remnants: the X-ray perspective

    Science.gov (United States)

    Vink, Jacco

    2012-12-01

    Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects. And in particular the advances made in X-ray imaging spectroscopy over the last two decades has greatly increased our knowledge about supernova remnants. It has made it possible to map the products of fresh nucleosynthesis, and resulted in the identification of regions near shock fronts that emit X-ray synchrotron radiation. Since X-ray synchrotron radiation requires 10-100 TeV electrons, which lose their energies rapidly, the study of X-ray synchrotron radiation has revealed those regions where active and rapid particle acceleration is taking place. In this text all the relevant aspects of X-ray emission from supernova remnants are reviewed and put into the context of supernova explosion properties and the physics and evolution of supernova remnants. The first half of this review has a more tutorial style and discusses the basics of supernova remnant physics and X-ray spectroscopy of the hot plasmas they contain. This includes hydrodynamics, shock heating, thermal conduction, radiation processes, non-equilibrium ionization, He-like ion triplet lines, and cosmic ray acceleration. The second half offers a review of the advances made in field of X-ray spectroscopy of supernova remnants during the last 15 year. This period coincides with the availability of X-ray imaging spectrometers. In addition, I discuss the results of high resolution X-ray spectroscopy with the Chandra and XMM-Newton gratings. Although these instruments are not ideal for studying extended sources, they nevertheless provided interesting results for a limited number of remnants. These results provide a glimpse of what may be achieved with future microcalorimeters that will be available on board future X-ray

  17. Nonrelativistic quantum X-ray physics

    CERN Document Server

    Hau-Riege, Stefan P

    2015-01-01

    Providing a solid theoretical background in photon-matter interaction, Nonrelativistic Quantum X-Ray Physics enables readers to understand experiments performed at XFEL-facilities and x-ray synchrotrons. As a result, after reading this book, scientists and students will be able to outline and perform calculations of some important x-ray-matter interaction processes. Key features of the contents are that the scope reaches beyond the dipole approximation when necessary and that it includes short-pulse interactions. To aid the reader in this transition, some relevant examples are discussed in detail, while non-relativistic quantum electrodynamics help readers to obtain an in-depth understanding of the formalisms and processes. The text presupposes a basic (undergraduate-level) understanding of mechanics, electrodynamics, and quantum mechanics. However, more specialized concepts in these fields are introduced and the reader is directed to appropriate references. While primarily benefiting users of x-ray light-sou...

  18. Cosmic microwave background: Polarization and temperature anisotropies from symmetric structures

    Science.gov (United States)

    Baccigalupi, Carlo

    1999-06-01

    Perturbations in the cosmic microwave background (CMB) are generated by primordial inhomogeneities. I consider the case of CMB anisotropies from one single ordered perturbation source, or seed, existing well before decoupling between matter and radiation. Such structures could have been left by high energy symmetries breaking in the early universe. I focus on the cases of spherical and cylindrical symmetry of the seed. I give general analytic expressions for the polarization and temperature linear perturbations, factoring out of the Fourier integral the dependence on the photon propagation direction and on the geometric coordinates describing the seed. I show how the CMB perturbations manifestly reflect the symmetries of their seeds. In particular, polarization is uniquely linked to the shape of the source because of its tensorial nature. CMB anisotropies are obtained with a line of sight integration. They are a function of the position and orientation of the seed along the photons path. This treatment highlights the undulatory properties of the CMB. I show with numerical examples how the polarization and temperature perturbations propagate beyond the size of their seeds, reaching the CMB sound horizon at the time considered. Just like the waves from a pebble thrown in a pond, CMB anisotropy from a seed intersecting the last scattering surface appears as a series of temperature and polarization waves surrounding the seed, extending on the scale of the CMB sound horizon at decoupling, roughly 1 deg in the sky. Each wave is characterized by its own value of the CMB perturbation, with the same mean amplitude of the signal coming from the seed interior; as expected for a linear structure with size L<=H-1 and density contrast δ at decoupling, the temperature anisotropy is δT/T~=δ(L/H-1)2, roughly ten times stronger than the polarization. These waves could allow one to distinguish relics from high energy processes of the early universe from pointlike astrophysical

  19. Non-linear evolution of the cosmic neutrino background

    Energy Technology Data Exchange (ETDEWEB)

    Villaescusa-Navarro, Francisco; Viel, Matteo [INAF/Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143, Trieste (Italy); Bird, Simeon [Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ, 08540 (United States); Peña-Garay, Carlos, E-mail: villaescusa@oats.inaf.it, E-mail: spb@ias.edu, E-mail: penya@ific.uv.es, E-mail: viel@oats.inaf.it [Instituto de Física Corpuscular, CSIC-UVEG, E-46071, Paterna, Valencia (Spain)

    2013-03-01

    We investigate the non-linear evolution of the relic cosmic neutrino background by running large box-size, high resolution N-body simulations which incorporate cold dark matter (CDM) and neutrinos as independent particle species. Our set of simulations explore the properties of neutrinos in a reference ΛCDM model with total neutrino masses between 0.05-0.60 eV in cold dark matter haloes of mass 10{sup 11}−10{sup 15} h{sup −1}M{sub s}un, over a redshift range z = 0−2. We compute the halo mass function and show that it is reasonably well fitted by the Sheth-Tormen formula, once the neutrino contribution to the total matter is removed. More importantly, we focus on the CDM and neutrino properties of the density and peculiar velocity fields in the cosmological volume, inside and in the outskirts of virialized haloes. The dynamical state of the neutrino particles depends strongly on their momentum: whereas neutrinos in the low velocity tail behave similarly to CDM particles, neutrinos in the high velocity tail are not affected by the clustering of the underlying CDM component. We find that the neutrino (linear) unperturbed momentum distribution is modified and mass and redshift dependent deviations from the expected Fermi-Dirac distribution are in place both in the cosmological volume and inside haloes. The neutrino density profiles around virialized haloes have been carefully investigated and a simple fitting formula is provided. The neutrino profile, unlike the cold dark matter one, is found to be cored with core size and central density that depend on the neutrino mass, redshift and mass of the halo, for halos of masses larger than ∼ 10{sup 13.5}h{sup −1}M{sub s}un. For lower masses the neutrino profile is best fitted by a simple power-law relation in the range probed by the simulations. The results we obtain are numerically converged in terms of neutrino profiles at the 10% level for scales above ∼ 200 h{sup −1}kpc at z = 0, and are stable with

  20. Multichroic Bolometric Detector Architecture for Cosmic Microwave Background Polarimetry Experiments

    Science.gov (United States)

    Suzuki, Aritoki

    Characterization of the Cosmic Microwave Background (CMB) B-mode polarization signal will test models of inflationary cosmology, as well as constrain the sum of the neutrino masses and other cosmological parameters. The low intensity of the B-mode signal combined with the need to remove polarized galactic foregrounds requires a sensitive millimeter receiver and effective methods of foreground removal. Current bolometric detector technology is reaching the sensitivity limit set by the CMB photon noise. Thus, we need to increase the optical throughput to increase an experiment's sensitivity. To increase the throughput without increasing the focal plane size, we can increase the frequency coverage of each pixel. Increased frequency coverage per pixel has additional advantage that we can split the signal into frequency bands to obtain spectral information. The detection of multiple frequency bands allows for removal of the polarized foreground emission from synchrotron radiation and thermal dust emission, by utilizing its spectral dependence. Traditionally, spectral information has been captured with a multi-chroic focal plane consisting of a heterogeneous mix of single-color pixels. To maximize the efficiency of the focal plane area, we developed a multi-chroic pixel. This increases the number of pixels per frequency with same focal plane area. We developed multi-chroic antenna-coupled transition edge sensor (TES) detector array for the CMB polarimetry. In each pixel, a silicon lens-coupled dual polarized sinuous antenna collects light over a two-octave frequency band. The antenna couples the broadband millimeter wave signal into microstrip transmission lines, and on-chip filter banks split the broadband signal into several frequency bands. Separate TES bolometers detect the power in each frequency band and linear polarization. We will describe the design and performance of these devices and present optical data taken with prototype pixels and detector arrays. Our

  1. Cosmic microwave background constraints for global strings and global monopoles

    Science.gov (United States)

    Lopez-Eiguren, Asier; Lizarraga, Joanes; Hindmarsh, Mark; Urrestilla, Jon

    2017-07-01

    We present the first cosmic microwave background (CMB) power spectra from numerical simulations of the global O(N) linear σ-model, with N=2,3, which have global strings and monopoles as topological defects. In order to compute the CMB power spectra we compute the unequal time correlators (UETCs) of the energy-momentum tensor, showing that they fall off at high wave number faster than naive estimates based on the geometry of the defects, indicating non-trivial (anti-)correlations between the defects and the surrounding Goldstone boson field. We obtain source functions for Einstein-Boltzmann solvers from the UETCs, using a recently developed method that improves the modelling at the radiation-matter transition. We show that the interpolation function that mimics the transition is similar to other defect models, but not identical, confirming the non-universality of the interpolation function. The CMB power spectra for global strings and global monopoles have the same overall shape as those obtained using the non-linear σ-model approximation, which is well captured by a large-N calculation. However, the amplitudes are larger than the large-N calculation would naively predict, and in the case of global strings much larger: a factor of 20 at the peak. Finally we compare the CMB power spectra with the latest CMB data in other to put limits on the allowed contribution to the temperature power spectrum at multipole l = 10 of 1.7% for global strings and 2.4% for global monopoles. These limits correspond to symmetry-breaking scales of 2.9× 1015 GeV (6.3× 1014 GeV with the expected logarithmic scaling of the effective string tension between the simulation time and decoupling) and 6.4× 1015 GeV respectively. The bound on global strings is a significant one for the ultra-light axion scenario with axion masses ma lesssim 10-28 eV . These upper limits indicate that gravitational waves from global topological defects will not be observable at the gravitational wave observatory

  2. The International X-ray Observatory - RFI#1

    CERN Document Server

    Bookbinder, Jay

    2010-01-01

    The International X-ray Observatory (IXO), a joint NASA-ESA-JAXA effort, will address fundamental and timely questions in astrophysics: What happens close to a black hole? How did supermassive black holes grow? How does large scale structure form? What is the connection between these processes? To address these science questions, IXO will trace orbits close to the event horizon of black holes, measure black hole spin for several hundred active galactic nuclei (AGN), use spectroscopy to characterize outflows and the environment of AGN during their peak activity, search for supermassive black holes out to redshift z = 10, map bulk motions and turbulence in galaxy clusters, find the missing baryons in the cosmic web using background quasars, and observe the process of cosmic feedback where black holes inject energy on galactic and intergalactic scales. IXO will employ optics with 20 times more collecting area at 1 keV than any previous X-ray observatory. Focal plane instruments will deliver a 100-fold increase i...

  3. The first stars: formation under X-ray feedback

    Science.gov (United States)

    Hummel, Jacob A.; Stacy, Athena; Jeon, Myoungwon; Oliveri, Anthony; Bromm, Volker

    2015-11-01

    We investigate the impact of a cosmic X-ray background (CXB) on Population III stars forming in a minihalo at z ≃ 25. Using the smoothed particle hydrodynamics code GADGET-2, we attain sufficient numerical resolution to follow gas collapsing into the centre of the minihalo from cosmological initial conditions up to densities of 1012 cm-3, at which point we form sink particles. This allows us to study how the presence of a CXB affects the formation of H2 and HD in the gas prior to becoming fully molecular. Using a suite of simulations for a range of possible CXB models, we follow each simulation for 5000 yr after the first sink particle forms. The CXB provides two competing effects, with X-rays both heating the gas and increasing the free electron fraction, allowing more H2 to form. X-ray heating dominates below n ˜ 1 cm-3, while the additional H2 cooling becomes more important above n ˜ 102 cm-3. The gas becomes optically thick to X-rays as it exits the quasi-hydrostatic `loitering phase', such that the primary impact of the CXB is to cool the gas at intermediate densities, resulting in an earlier onset of baryonic collapse into the dark matter halo. At the highest densities, self-shielding results in similar thermodynamic behaviour across a wide range of CXB strengths. Consequently, we find that star formation is relatively insensitive to the presence of a CXB; both the number and the characteristic mass of the stars formed remains quite similar even as the strength of the CXB varies by several orders of magnitude.

  4. Rings and spots in the structure of the cosmic background radiation

    Energy Technology Data Exchange (ETDEWEB)

    Argueeso, F.; Martinez-Gonzalez, E.; Sanz, J.L.

    1989-01-01

    The influence of a large-scale spherical mass concentration (or void) on the microwave and X-ray backgrounds is studied. Rings and spots in the sky patterns appear due to focusing of the photons, once the monopole and dipole amplitude have been subtracted to avoid contamination by local structures. It is shown how maps over the whole sky can help to identify such a dominant structure. 23 references.

  5. MCNP6 Cosmic & Terrestrial Background Particle Fluxes -- Release 4

    Energy Technology Data Exchange (ETDEWEB)

    McMath, Garrett E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.; McKinney, Gregg W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.; Wilcox, Trevor [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Engineering and Nonproliferation Div.

    2015-01-23

    Essentially a set of slides, the presentation begins with the MCNP6 cosmic-source option, then continues with the MCNP6 transport model (atmospheric, terrestrial) and elevation scaling. It concludes with a few slides on results, conclusions, and suggestions for future work.

  6. X-Ray Astronomy

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  7. X-ray lithography masking

    Science.gov (United States)

    Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

    1998-01-01

    X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

  8. Cosmic Muon Induced Backgrounds in the Daya Bay Reactor Neutrino Experiment

    CERN Document Server

    Dengjie, Li

    2014-01-01

    Muon induced neutrons and long-lived radioactive isotopes are important background sources for low-energy underground experiments. We study the produced processes and properties of cosmic muon induced backgrounds, show the muon veto system used for rejecting these backgrounds and the methods to estimate residual backgrounds in the Daya Bay Reactor Neutrino Experiment.

  9. X-ray luminosity functions of different morphological and X-ray type AGN populations

    CERN Document Server

    Pović, M; Sánchez-Portal, M; Bongiovanni, A; Cepa, J; Lorenzo, M Fernández; Lara-López, M A; Gallego, J; Ederoclite, A; Márquez, I; Masegosa, J; Alfaro, E; Castañeda, H; González-Serrano, J I; González, J J; 10.1002/asna.201211840

    2013-01-01

    Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray luminosity functions of X-ray detected AGN in the SXDS and GWS fields. The limiting fluxes of our samples are 9.0x10^(-15) and 4.8x10^(-16) erg/cm^2/sec^(-1) in the 0.5 - 7.0 keV band in the two fields, respectively. We carried out analysis in three X-ray bands and in two redshift intervals up to z < 1.4. Moreover, we derive the luminosity functions for different optical morphologies and X-ray types. We confirm strong luminosity evolution in all three bands, finding the most luminous objects at higher redshift. However, no signs of density evolution are found in any tested X-ray band. We obtain similar results for compact and early-type objects. Finally, we observe the `Steffen effect', where X-ray type-1 sources are more numerous at higher luminosities in comparison with type-2 sources.

  10. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body. X-rays are the oldest and most frequently used form of medical imaging. A bone ... bones. top of page How should I prepare? Most bone x-rays require no special preparation. You ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... tissue shows up in shades of gray and air appears black. Until recently, x-ray images were ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  13. Soft X-ray Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seely, John

    1999-05-20

    The contents of this report cover the following: (1) design of the soft x-ray telescope; (2) fabrication and characterization of the soft x-ray telescope; and (3) experimental implementation at the OMEGA laser facility.

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  15. Bone X-Ray (Radiography)

    Science.gov (United States)

    ... clothing that might interfere with the x-ray images. Women should always inform their physician and x-ray ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures ...

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Us News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses ... assess trauma patients in emergency departments. A CT scan can image complicated fractures, subtle fractures or dislocations. ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that ...

  20. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very small dose ... to produce pictures of the inside of the abdominal cavity. It is used to evaluate the stomach, liver, ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... radiation like light or radio waves. X-rays pass through most objects, including the body. Once it ... organs, allow more of the x-rays to pass through them. As a result, bones appear white ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... and x-rays. A Word About Minimizing Radiation Exposure Special care is taken during x-ray examinations ... patient's body not being imaged receive minimal radiation exposure. top of page What are the limitations of ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... and Media Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to X-ray ( ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  6. Cosmic Microwave Background and Density Fluctuations from Strings plus Inflation

    CERN Document Server

    Contaldi, C; Magueijo, J; Contaldi, Carlo; Hindmarsh, Mark; Magueijo, Joao

    1999-01-01

    In cosmological models where local cosmic strings are formed at the end of a period of inflation, the perturbations are seeded both by the defects and by the quantum fluctuations. In a subset of these models, for example those based on $D$-term inflation, the amplitudes are similar. Using our recent calculations of structure formation with cosmic strings, we point out that in a flat cosmology with zero cosmological constant and 5% baryonic component, strings plus inflation fits the observational data much better than each component individually. The large-angle CMB spectrum is mildly tilted, for Harrison-Zeldovich inflationary fluctuations. It then rises to a thick Doppler bump, covering $\\ell=200-600$, modulated by soft secondary undulations. The standard CDM anti-biasing problem is cured, giving place to a slightly biased scenario of galaxy formation.

  7. X-Ray Exam: Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip A A A What's in ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that ...

  8. X-Ray Exam: Finger

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger A A A What's in ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that ...

  9. X-Ray Exam: Foot

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot A A A What's in ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that ...

  10. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist A A A What's in ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that ...

  11. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that ...

  12. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis A A A What's in ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that ...

  13. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm A A A What's in ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that ...

  14. X-ray selected BALQSOs

    CERN Document Server

    Page, M J; Ceballos, M; Corral, A; Ebrero, J; Esquej, P; Krumpe, M; Mateos, S; Rosen, S; Schwope, A; Streblyanska, A; Symeonidis, M; Tedds, J A; Watson, M G

    2016-01-01

    We study a sample of six X-ray selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index alpha=0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, alpha_OX, of the X-ray selected BALQSOs, have a mean value of 1.69 +- 0.05, which is similar to that found for X-ray selected and optically selected non-BAL QSOs of similar ultraviolet luminosity. In contrast, optically-selected BALQSOs typically have much larger alpha_OX and so are characterised as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray sp...

  15. X-ray Crystallography Facility

    Science.gov (United States)

    2000-01-01

    Edward Snell, a National Research Council research fellow at NASA's Marshall Space Flight Center (MSFC), prepares a protein crystal for analysis by x-ray crystallography as part of NASA's structural biology program. The small, individual crystals are bombarded with x-rays to produce diffraction patterns, a map of the intensity of the x-rays as they reflect through the crystal.

  16. Relic Right-handed Dirac Neutrinos and Implications for Detection of Cosmic Neutrino Background

    CERN Document Server

    Zhang, Jue

    2015-01-01

    It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos $\

  17. Cosmic Microwave Background Anisotropies from Scaling Seeds Fit to Observational Data

    OpenAIRE

    Durrer, Ruth; Kunz, Martin; Lineweaver, C. H.; Sakellariadou, Mairi

    1997-01-01

    We compute cosmic microwave background angular power spectra for scaling seed models of structure formation. A generic parameterization of the energy momentum tensor of the seeds is employed. We concentrate on two regions of parameter space inspired by global topological defects: O(4) texture models and the large-N limit of O(N) models. We use $\\chi^{2}$ fitting to compare these models to recent flat-band power measurements of the cosmic microwave background. Only scalar perturbations are con...

  18. SMM x ray polychromator

    Science.gov (United States)

    Saba, J. L. R.

    1993-01-01

    The objective of the X-ray Polychromator (XRP) experiment was to study the physical properties of solar flare plasma and its relation to the parent active region to understand better the flare mechanism and related solar activity. Observations were made to determine the temperature, density, and dynamic structure of the pre-flare and flare plasma as a function of wavelength, space and time, the extent to which the flare plasma departs from thermal equilibrium, and the variation of this departure with time. The experiment also determines the temperature and density structure of active regions and flare-induced changes in the regions.

  19. X-ray today

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, U. [Philips Medical Systems, Hamburg (Germany)

    2001-09-01

    The interest attracted by the new imaging modalities tends to overshadow the continuing importance of projection radiography and fluoroscopy. Nevertheless, projection techniques still represent by far the greatest proportion of diagnostic imaging examinations, and play an essential role in the growing number of advanced interventional procedures. This article describes some of the latest developments in X-ray imaging technology, using two products from the Philips range as examples: the Integris Allura cardiovascular system with 3D image reconstruction, and the BV Pulsera: a high-end, multi-functional mobile C-arm system with cardiac capabilities. (orig.)

  20. DNDO Report: Predicting Solar Modulation Potentials for Modeling Cosmic Background Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Behne, Patrick Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-08

    The modeling of the detectability of special nuclear material (SNM) at ports and border crossings requires accurate knowledge of the background radiation at those locations. Background radiation originates from two main sources, cosmic and terrestrial. Cosmic background is produced by high-energy galactic cosmic rays (GCR) entering the atmosphere and inducing a cascade of particles that eventually impact the earth’s surface. The solar modulation potential represents one of the primary inputs to modeling cosmic background radiation. Usosokin et al. formally define solar modulation potential as “the mean energy loss [per unit charge] of a cosmic ray particle inside the heliosphere…” Modulation potential, a function of elevation, location, and time, shares an inverse relationship with cosmic background radiation. As a result, radiation detector thresholds require adjustment to account for differing background levels, caused partly by differing solar modulations. Failure to do so can result in higher rates of false positives and failed detection of SNM for low and high levels of solar modulation potential, respectively. This study focuses on solar modulation’s time dependence, and seeks the best method to predict modulation for future dates using Python. To address the task of predicting future solar modulation, we utilize both non-linear least squares sinusoidal curve fitting and cubic spline interpolation. This material will be published in transactions of the ANS winter meeting of November, 2016.

  1. Lower Bound on the Cosmic TeV Gamma-ray Background Radiation

    CERN Document Server

    Inoue, Yoshiyuki

    2015-01-01

    The Fermi gamma-ray space telescope has revolutionized our understanding of the cosmic gamma-ray background radiation in the GeV band. However, investigation on the cosmic TeV gamma-ray background radiation still remains sparse. Here, we report the lower bound on the cosmic TeV gamma-ray background spectrum placed by the cumulative flux of individual detected extragalactic TeV sources including blazars, radio galaxies, and starburst galaxies. The current limit on the cosmic TeV gamma-ray background above 0.1 TeV is obtained as $3\\times10^{-8} (E/100~{\\rm GeV})^{-0.6} \\exp(-E/2000~{\\rm GeV})~{\\rm [GeV/cm^2/s/sr]} < E^2dN/dE < 1\\times10^{-7} (E/100~{\\rm GeV})^{-0.5}~{\\rm [GeV/cm^2/s/sr]}$, where the upper bound is set by requirement that the cascade flux from the cosmic TeV gamma-ray background radiation can not exceed the measured cosmic GeV gamma-ray background spectrum (Inoue & Ioka 2012). Two nearby blazars, Mrk 421 and Mrk 501, explain ~70% of the cumulative flux at 0.8-4 TeV, while extreme blaza...

  2. DNDO Report: Predicting Solar Modulation Potentials for Modeling Cosmic Background Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Behne, Patrick Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-08

    The modeling of the detectability of special nuclear material (SNM) at ports and border crossings requires accurate knowledge of the background radiation at those locations. Background radiation originates from two main sources, cosmic and terrestrial. Cosmic background is produced by high-energy galactic cosmic rays (GCR) entering the atmosphere inducing a cascade of particles that eventually impact the earth’s surface. The solar modulation potential represents one of the primary inputs to modeling cosmic background radiation. Usosokin et al. formally define solar modulation potential as “the mean energy loss [per unit charge] of a cosmic ray particle inside the heliosphere…” Modulation potential, a function of elevation, location, and time, shares an inverse relationship with cosmic background radiation. As a result, radiation detector thresholds require adjustment to account for differing background levels, caused partly by differing solar modulations. Failure to do so can result in higher rates of false positives and failed detection of SNM for low and high levels of solar modulation potential, respectively. This study focuses on solar modulation’s time dependence and seeks the best method to predict modulation for future dates using Python. To address the task of predicting future solar modulation, we utilize both non-linear least squares sinusoidal curve fitting and cubic spline interpolation. This material will be published in transactions of the ANS winter meeting of November, 2016.

  3. Operation of an InGrid based X-ray detector at the CAST experiment

    Energy Technology Data Exchange (ETDEWEB)

    Krieger, Christoph; Desch, Klaus; Kaminski, Jochen; Lupberger, Michael [Physikalisches Institut, Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany)

    2015-07-01

    The CERN Axion Solar Telescope (CAST) is searching for axions and other new particles emerging from the Sun and coupling to photons. Those particles are converted into soft X-ray photons in a high magnetic field. To enhance sensitivity for physics beyond the Standard Model it is necessary to cope with weak couplings and low energies, thus requiring an efficient background discrimination as well as a detection threshold below 1 keV. Both requirements are fulfilled by an X-ray detector based on the combination of a Micromegas gas amplification stage with a highly integrated pixel chip (InGrid) which allows to make full use of the Micromegas structure's granularity. The necessary precision in fabrication is achieved by the use of photolithographic postprocessing techniques. The high spatial resolution allows for a topological suppression of background events originating from cosmic rays as well as for the low detection threshold as single electrons can be detected. After the detector's energy threshold was evaluated at an X-ray generator to be low enough to allow for the detection of the carbon K{sub α} line at 277 eV, the detector was mounted at one of CAST's X-ray telescopes and installed along with the necessary infrastructure in 2014. The data taken during the CAST run 2014 is being analysed. Background studies and rates are presented as a first result.

  4. Handbook of X-Ray Astronomy

    Science.gov (United States)

    Arnaud, Keith A. (Editor); Smith, Randall K.; Siemiginowska, Aneta

    2011-01-01

    X-ray astronomy was born in the aftermath of World War II as military rockets were repurposed to lift radiation detectors above the atmosphere for a few minutes at a time. These early flights detected and studied X-ray emission from the Solar corona. The first sources beyond the Solar System were detected during a rocket flight in 1962 by a team headed by Riccardo Giaccom at American Science and Engineering, a company founded by physicists from MIT. The rocket used Geiger counters with a system designed to reduce non-X-ray backgrounds and collimators limiting the region of sky seen by the counters. As the rocket spun, the field of view (FOV) happened to pass over what was later found to be the brightest non-Solar X-ray source; later designated See X-1. It also detected a uniform background glow which could not be resolved into individual sources. A follow-up campaign using X-ray detectors with better spatial resolution and optical telescopes identified See X-1 as an interacting binary with a compact (neutron star) primary. This success led to further suborbital rocket flights by a number of groups. More X-ray binaries were discovered, as well as X-ray emission from supernova remnants, the radio galaxies M87 and Cygnus-A, and the Coma cluster. Detectors were improved and Geiger counters were replaced by proportional counters, which provided information about energy spectra of the sources. A constant challenge was determining precise positions of sources as only collimators were available.

  5. X-ray lithography source

    Science.gov (United States)

    Piestrup, Melvin A.; Boyers, David G.; Pincus, Cary

    1991-01-01

    A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and elminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an exellent moderate-priced X-ray source for lithography.

  6. Observations of cosmic gamma ray bursts with WATCH on EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, N.; Castro-Tirado, A. J.

    1995-01-01

    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy, trap...

  7. Cosmic microwave background experiments targeting the cosmic strings Doppler peak signal

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Hobson, Mike

    1996-01-01

    We investigate which experiments are better suited to test the robust prediction that cosmic strings do not produce secondary Doppler peaks. We propose a statistic for detecting oscillations in the C^l spectrum, and study its statistical relevance given the truth of an inflationary competitor to cosmic strings. The analysis is performed for single-dish experiments and interferometers, subject to a variety of noise levels and scanning features. A high resolution of 0.2 degrees is found to be required for single-dish experiments with realistic levels of noise. Interferometers appear to be more suitable for detecting this signal.

  8. Cosmic Strings and Their Induced Non-Gaussianities in the Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Christophe Ringeval

    2010-01-01

    small fraction of the CMB angular power spectrum, cosmic strings could actually be the main source of its non-Gaussianities. In this paper, after having reviewed the basic cosmological properties of a string network, we present the signatures Nambu-Goto cosmic strings would induce in various observables ranging from the one-point function of the temperature anisotropies to the bispectrum and trispectrum. It is shown that string imprints are significantly different than those expected from the primordial type of non-Gaussianity and could therefore be easily distinguished.

  9. Remaining Problems in Interpretation of the Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Hans-Jörg Fahr

    2015-01-01

    Full Text Available By three independent hints it will be demonstrated that still at present there is a substantial lack of theoretical understanding of the CMB phenomenon. One point, as we show, is that at the phase of the recombination era one cannot assume complete thermodynamic equilibrium conditions but has to face both deviations in the velocity distributions of leptons and baryons from a Maxwell-Boltzmann distribution and automatically correlated deviations of photons from a Planck law. Another point is that at the conventional understanding of the CMB evolution in an expanding universe one has to face growing CMB temperatures with growing look-back times. We show, however, here that the expected CMB temperature increases would be prohibitive to star formation in galaxies at redshifts higher than z=2 where nevertheless the cosmologically most relevant supernovae have been observed. The third point in our present study has to do with the assumption of a constant vacuum energy density which is required by the present ΛCDM-cosmology. Our studies here rather lead to the conclusion that cosmic vacuum energy density scales with the inverse square of the cosmic expansion scale R=R(t. Thus we come to the conclusion that with the interpretation of the present-day high quality CMB data still needs to be considered carefully.

  10. Cosmic Microwave Background Anisotropy Induced by Cosmic Strings on Angular Scales {approx_gt}15{sup {prime} }

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B. [Department of Physics, University of Wisconsin---Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States); Caldwell, R.R. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19106 (United States); Dodelson, S.; Stebbins, A. [NASA/Fermilab Astrophysics Center, P.O. Box 500, Batavia, Illinois 60510 (United States); Knox, L. [Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, M5S 3H8 (Canada); Shellard, E.P. [University of Cambridge, D.A.M.T.P. Silver Street, Cambridge CB3 9EW (United Kingdom)

    1997-10-01

    We have computed an estimate of the angular power spectrum of the cosmic microwave background induced by cosmic strings on angular scales {approx_gt}15{sup {prime}}, using a numerical simulation of a cosmic string network and have decomposed this pattern into scalar, vector, and tensor parts. The anisotropies from vector modes dominate except on very small angular scales, and we find no evidence for strong acoustic oscillations in the scalar anisotropy. The anisotropies generated after recombination are even more important than in adiabatic models. The total anisotropy on small scales is inconsistent with current measurements. The calculation has a number of uncertainties, the largest of which is due to finite temporal range. {copyright} {ital 1997} {ital The American Physical Society}

  11. Nonlinear evolution of cosmic magnetic fields and cosmic microwave background anisotropies

    Science.gov (United States)

    Tashiro, Hiroyuki; Sugiyama, Naoshi; Banerjee, Robi

    2006-01-01

    In this work we investigate the effects of primordial magnetic fields on cosmic microwave background anisotropies (CMB). Based on cosmological magneto-hydro dynamic (MHD) simulations [R. Banerjee and K. Jedamzik, Phys. Rev. DPRVDAQ0556-2821 70, 123003 (2004).10.1103/PhysRevD.70.123003] we calculate the CMB anisotropy spectra and polarization induced by fluid fluctuations (Alfvén modes) generated by primordial magnetic fields. The strongest effect on the CMB spectra comes from the transition epoch from a turbulent regime to a viscous regime. The balance between magnetic and kinetic energy until the onset of the viscous regime provides a one to one relation between the comoving coherence length L and the comoving magnetic field strength B, such as L˜30(B/10-9Gauss)3pc. The resulting CMB temperature and polarization anisotropies for the initial power law index of the magnetic fields n>3/2 are somewhat different from the ones previously obtained by using linear perturbation theory. In particular, differences can appear on intermediate scales l20000. On scales l0.7Mpc for the most extreme case, or B0.8Mpc for the most conservative case. We may also expect higher signals on large scales of the polarization spectra compared to linear calculations. The signal may even exceed the B-mode polarization from gravitational lensing depending on the strength of the primordial magnetic fields. On very small scales, the diffusion damping scale of nonlinear calculations turns out to be much smaller than the one of linear calculations if the comoving magnetic field strength B>16nGauss. If the magnetic field strength is smaller, the diffusion scales become smaller too. Therefore we expect to have both, temperature and polarization anisotropies, even beyond l>10000 regardless of the strength of the magnetic fields. The peak values of the temperature anisotropy and the B-mode polarization spectra are approximately 40μK and a few μK, respectively.

  12. Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of their Matter Content

    CERN Document Server

    Georganopoulos, M; Perlman, E; Stecker, F; Georganopoulos, {Markos; Kazanas, Demosthenes; Perlman, Eric; Stecker, Floyd

    2005-01-01

    We propose a method for estimating the composition, i.e. the relative amounts of leptons and protons, of extragalactic jets which exhibit X-ray bright knots in their kpc scale jets. The method relies on measuring, or setting upper limits on, the component of the Cosmic Microwave Background (CMB) radiation that is bulk-Comptonized by cold electrons in the relativistically flowing jet. These measurements, along with modeling of the broadband knot emission that constrain the bulk Lorentz factor of the jets, can yield estimates of the jet power carried by protons and leptons. We provide an explicit calculation of the spectrum of the bulk-Comptonized (BC) CMB component and apply these results to PKS 0637--752 and 3C 273, two superluminal quasars with Chandra-detected large scale jets. What makes these sources particularly suited for such a procedure is the absence of significant non-thermal jet emission in the `bridge', the region between the core and the first bright jet knot, which guarantees that most of the el...

  13. Cosmic microwave background anomalies in an open universe.

    Science.gov (United States)

    Liddle, Andrew R; Cortês, Marina

    2013-09-13

    We argue that the observed large-scale cosmic microwave anomalies, discovered by WMAP and confirmed by the Planck satellite, are most naturally explained in the context of a marginally open universe. Particular focus is placed on the dipole power asymmetry, via an open universe implementation of the large-scale gradient mechanism of Erickcek et al. Open inflation models, which are motivated by the string landscape and which can excite "supercurvature" perturbation modes, can explain the presence of a very-large-scale perturbation that leads to a dipole modulation of the power spectrum measured by a typical observer. We provide a specific implementation of the scenario which appears compatible with all existing constraints.

  14. The impact of superstructures in the Cosmic Microwave Background

    Science.gov (United States)

    Ilić, Stéphane; Langer, Mathieu; Douspis, Marian

    2016-10-01

    In 2008, Granett et al. claimed a direct detection of the integrated Sachs-Wolfe (iSW) effect, through the stacking of CMB patches at the positions of identified superstructures. Additionally, the high amplitude of their measured signal was reported to be at odds with predictions from the standard model of cosmology. However, a closer inspection of these results prompts multiple questions, more specifically about the amplitude and significance of the expected signal. We propose here an original theoretical prediction of the iSW effect produced by such superstructures. We use simulations based on GR and the LTB metric to reproduce cosmic structures and predict their exact theoretical iSW effect on the CMB. The amplitudes predicted with this method are consistent with the signal measured when properly accounting the contribution of the non-negligible (and fortuitous) primordial CMB fluctuations to the total signal. It also highlights the tricky nature of stacking measurements and their interpretation.

  15. X-Ray Polarimetry with GEMS

    Science.gov (United States)

    Strohmayer, Tod

    2011-01-01

    The polarization properties of cosmic X-ray sources are still largely unexplored. The Gravity and Extreme Magnetism SMEX (GEMS) will carry out the first sensitive X-ray polarization survey of a wide range of sources including; accreting compact objects (black holes and neutron stars), AGN, supernova remnants, magnetars and rotation-powered pulsars. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect to achieve high polarization sensitivity in the 2 - 10 keV band. I will provide an update of the project status, illustrate the expected performance with several science examples, and provide a brief overview of the data analysis challenges

  16. Nanobeam X-ray scattering probing matter at the nanoscale

    CERN Document Server

    Stangl, Julian; Chamard, Virginie; Carbone, Dina

    2013-01-01

    A comprehensive overview of the possibilities and potential of X-ray scattering using nanofocused beams for probing matter at the nanoscale, including guidance on the design of nanobeam experiments. The monograph discusses various sources, including free electron lasers, synchrotron radiation and other portable and non-portable X-ray sources.For scientists using synchrotron radiation or students and scientists with a background in X-ray scattering methods in general.

  17. Inter-galactic Shock Acceleration and the Cosmic Gamma-ray Background

    CERN Document Server

    Miniati, F

    2002-01-01

    We investigate numerically the contribution to the cosmic gamma-ray background from cosmic-rays ions and electrons accelerated at inter-galactic (IG) shocks associated with cosmological structure formation. We show that the kinetic energy of accretion flows in the low-red-shift IG medium is thermalized primarily through moderately strong shocks, which allow for an efficient conversion of shock ram pressure into cosmic-ray pressure. Cosmic-rays accelerated at these shocks produce a diffuse gamma-ray flux which is dominated by inverse Compton emission from electrons scattering off cosmic microwave background photons. Decay of neutral pions generated in p-p inelastic collisions of the ionic cosmic-ray component with the thermal gas contribute about 30% of the computed emission. Based on experimental upper limits on the photon flux above 100 MeV from nearby clusters we constrain the efficiency of conversion of shock energy into relativistic CR electrons to less than 1%. Thus, we find that cosmic-rays of cosmologi...

  18. Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy

    CERN Document Server

    Pogosian, Levon; Wasserman, Ira; Wyman, Mark

    2008-01-01

    Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (l2000) will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.

  19. Cosmic Ray contribution to the WMAP polarization data on the Cosmic Microwave Background

    CERN Document Server

    Wibig, Tadeusz

    2015-01-01

    We have updated our analysis of the 9-year WMAP data using the collection of polarization maps looking for the presence of additional evidence for a finite 'cosmic ray foreground' for the CMB. We have given special attention to high Galactic latitudes, where the recent BICEP2 findings were reported. The method of examining the correlation with the observed gamma ray flux proposed in our earlier papers and applied to the polarization data shows that the foreground related to cosmic rays is still observed even at high Galactic altitudes and conclusions about gravitational waves are not yet secure. Theory has it that there is important information about inflationary gravitational waves in the fine structure of the CMB polarization properties (polarization vector and angle) and it is necessary to examine further the conclusions that can be gained from studies of the CMB maps, in view of the disturbing foreground effects.

  20. Reproducing the observed Cosmic microwave background anisotropies with causal scaling seeds

    OpenAIRE

    Durrer, R.; Kunz, M.; Melchiorri, A.

    2000-01-01

    During the last years it has become clear that global O(N) defects and U(1) cosmic strings do not lead to the pronounced first acoustic peak in the power spectrum of anisotropies of the cosmic microwave background which has recently been observed to high accuracy. Inflationary models cannot easily accommodate the low second peak indicated by the data. Here we construct causal scaling seed models which reproduce the first and second peak. Future, more precise CMB anisotropy and polarization ex...

  1. An SZ Temperature Decrement X-ray Luminosity Relation for Galaxy Clusters

    CERN Document Server

    Cooray, A R

    1999-01-01

    We present the observed relation between the cosmic microwave background (CMB) temperature decrement due to the Sunyaev-Zeldovich (SZ) effect and the X-ray luminosity of galaxy clusters. We discuss this relation in terms of the cluster properties, and show that the slope of the observed relation is in agreement with both the L-T relation based on numerical simulations and X-ray emission observations, and the M_gas-L relation based on observations. The slope of the Delta T_SZ-L relation is also consistent with the M_tot-L relation, where M_tot is the cluster total mass based on gravitational lensing observations. This agreement may be taken to imply a constant gas mass fraction within galaxy clusters, however, there are large uncertainties, dominated by observational errors, associated with these relations. Using the Delta T_SZ-L relation and the cluster X-ray luminosity function, we evaluate the local cluster contribution to arcminute scale cosmic microwave background anisotropies. The Compton distortion y-pa...

  2. Reionization and its imprint of the cosmic microwave background

    Science.gov (United States)

    Dodelson, Scott; Jubas, Jay M.

    1995-01-01

    Early reionization changes the pattern of anisotropies expected in the cosmic microwave backgrond. To explore these changes, we derive from first principles the equations governing anisotropies, focusing on the interactions of photons with electrons. Vishniac (1987) claimed that second-order terms can be large in a reionized universe, so we derive equations correct to second order in the perturbations. There are many more second-order terms than were considered by Vishniac. To understand the basic physics involved, we present a simple analytic approximation to the first-order equation. Then, turning to the second order equation, we show that the Vishniac term is indeed the only important one. We also present numerical results for a variety of ionization histories (in a standard cold dark matter universe) and show quantitatively how the signal in several experiments depends on the ionization history. The most pronounced indication of a reionized universe would be seen in very small scale experiments; the expected signal in the Owens Valley experiment is smaller by a factor of order 10 if the last scattering surface is at a redshift z approximately = 100 as it would be if the universe were reionized very early. On slightly larger scales, the expected signal in a reionized universe is smaller than it would be with standard recombination, but only a factor of 2 or so. The signal is even smaller in these experiments in the intermediate case where some photons last scattered at the standard recombination epoch.

  3. Cosmic Microwave Background Anisotropy Measurement From Python V

    CERN Document Server

    Coble, K; Dragovan, M; Ganga, K; Knox, L; Kovács, J; Ratra, B; Souradeep, T

    2003-01-01

    We analyze observations of the microwave sky made with the Python experiment in its fifth year of operation at the Amundsen-Scott South Pole Station in Antarctica. After modeling the noise and constructing a map, we extract the cosmic signal from the data. We simultaneously estimate the angular power spectrum in eight bands ranging from large (l ~ 40) to small (l ~ 260) angular scales, with power detected in the first six bands. There is a significant rise in the power spectrum from large to smaller (l ~ 200) scales, consistent with that expected from acoustic oscillations in the early Universe. We compare this Python V map to a map made from data taken in the third year of Python. Python III observations were made at a frequency of 90 GHz and covered a subset of the region of the sky covered by Python V observations, which were made at 40 GHz. Good agreement is obtained both visually (with a filtered version of the map) and via a likelihood ratio test.

  4. Topological X-Rays Revisited

    Science.gov (United States)

    Lynch, Mark

    2012-01-01

    We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

  5. Filtered fluorescer x-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, H.C.; Emig, J.A.; Thoe, R.S.; Springer, P.T.; Hernandez, J.A.

    1995-04-01

    Recently, an instrument capable of measuring x-rays between 8 and 90 keV was conceived to help understand conditions pertaining to pulsed power research. This resulted in the development of a versatile device that would incrementally detect x-rays emitted at predetermined energy bands over this range. To accomplish this, an array of well characterized filter-fluorescer combinations were produced which would allow fluoresced x-rays to be observed by time resolved electro-optical devices. As many as sixteen channels could be utilized with each channel having a corresponding background channel. Upon completion of the device, a three week series of experiments was then successfully carried out.

  6. X-ray instrumentation for SR beamlines

    CERN Document Server

    Kovalchuk, M V; Zheludeva, S I; Aleshko-Ozhevsky, O P; Arutynyan, E H; Kheiker, D M; Kreines, A Y; Lider, V V; Pashaev, E M; Shilina, N Y; Shishkov, V A

    2000-01-01

    The main possibilities and parameters of experimental X-ray stations are presented: 'Protein crystallography', 'X-ray structure analysis', 'High-precision X-ray optics', 'X-ray crystallography and material science', 'X-ray topography', 'Photoelectron X-ray standing wave' that are being installed at Kurchatov SR source by A.V. Shubnikov Institute of Crystallography.

  7. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  8. Soft X-ray optics

    CERN Document Server

    Spiller, Eberhard A

    1993-01-01

    This text describes optics mainly in the 10 to 500 angstrom wavelength region. These wavelengths are 50 to 100 times shorter than those for visible light and 50 to 100 times longer than the wavelengths of medical x rays or x-ray diffraction from natural crystals. There have been substantial advances during the last 20 years, which one can see as an extension of optical technology to shorter wavelengths or as an extension of x-ray diffraction to longer wavelengths. Artificial diffracting structures like zone plates and multilayer mirrors are replacing the natural crystals of x-ray diffraction.

  9. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  10. Cosmic-ray composition measurements and cosmic ray background-free γ -ray observations with Cherenkov telescopes

    Science.gov (United States)

    Neronov, Andrii; Semikoz, Dmitri V.; Vovk, Ievgen; Mirzoyan, Razmik

    2016-12-01

    The muon component of extensive air showers (EAS) initiated by cosmic-ray particles carries information on the primary particle identity. We show that the muon content of EAS could be measured in a broad energy range from 10-100 TeV up to ultra-high-energy cosmic-ray range using wide field-of-view imaging atmospheric Cherenkov telescopes observing strongly inclined or nearly horizontal EAS from the ground of from high altitude. Cherenkov emission from muons in such EAS forms a distinct component (halo or tail) of the EAS image in the telescope camera. We show that detection of the muon signal could be used to measure composition of the cosmic-ray spectrum in the energy ranges of the knee, the ankle and of the Galactic-to-extragalactic transition. It could also be used to veto the cosmic-ray background in gamma-ray observations. This technique provides a possibility for up to 2 orders of magnitude improvement of sensitivity for γ -ray flux in the energy band above 10 PeV, compared to KASCADE-Grande, and an order-of-magnitude improvement of sensitivity in the multi-EeV energy band, compared to Pierre Auger Observatory.

  11. The Energetics of 100 KPC X-Ray Jets

    Science.gov (United States)

    Schwartz, Daniel A.; Marshall, Herman L.; Gelbord, Jonathan; Worrall, Diana M.; Birkinshaw, Mark; Lovell, James J.; Jauncey, David L.; Perlman, Eric S.; Murphy, David W.

    We discuss the physical properties of 12 quasar jets as revealed by our Chandra X-ray and our ATCA and VLA radio observations. These 12 jets were detected in a 5 ksec snapshot survey of a sample of 20 bright flat spectrum radio sources with arcsec scale jets. When we interpret the X-ray emission as inverse Compton scattering of the radio emitting electrons on the Cosmic Microwave Background and assume equipartition we find that the emitting regions must be relativistically beamed even at distances 200 to 500 kpc from the quasar. We report on the structure of magnetic field strengths relativistic Doppler factors and kinetic flux as a function of distance from the quasar core. The minimum kinetic power is generally comparable to or larger than the quasar radiative luminosity implying that the jets must be a significant factor in the energetics of the accretion process powering the central black hole. This research has been funded in part by NASA contract NAS8-39073 to SAO and SAO SV1-61010 to MIT and NASA grant GO2-3151C to SAO. E.S.P. acknowledges support from NASA LTSA grant NAG5-9997. Part of this research was performed at JPL/CIT under contract to NASA.

  12. Cosmic infrared background fluctuations of the COSMOS field in the SPLASH survey: new measurements and the cosmological explanations

    Science.gov (United States)

    Li, Yanxia

    2017-01-01

    The cosmic infrared background (CIB) is the integrated emission of all sources through cosmic time and carries an abundance of information about the star formation and galaxy growth in the Universe. Due to significant and complex foregrounds from our Galaxy, the optimal way to study the unresolved background is to actually study its fluctuations, especially at large angular scales where they reflect the clustering of unresolved galaxies. Our new measurements of the CIB fluctuations reach the largest angular scale to date for such a study, thanks to new observations of the COSMOS field from the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH). We analyzed Spitzer IRAC 3.6 and 4.5 um data of the whole field, with an average depth of 1.33 hour/pixel over 4 epochs spanning 2 years. We found that the auto-power spectra are consistent among various epochs and are correlated at the two channels. We confirmed the previously detected excess flux at large scales of the power spectra.The cross-correlation of the CIB fluctuations with backgrounds at other wavelengths is an extremely useful technique to understand the excess flux. The previously seen CIB and X-ray background (CXB) cross-correlation suggests significant contribution to the CIB fluctuations from accreting black holes that is much higher than among any known populations, and such a cross-correlation is also used as an evidence for the existence of direct collapse black holes in the early Universe.In this talk, we will present the first CIB fluctuation measurements of the COSMOS field using the new SPLASH data and we will also revisit the CIB and CXB cross-correlation in this field, which is about 20 times larger than the previous study and therefore with much improved significance levels. Measuring CIB fluctuations is a powerful tool to study the large-scale structure of the Universe. The CIB and CXB cross-correlation can not only provide observational constrains on the theoretical modeling of the CIB

  13. The music of the Big Bang the cosmic microwave background and the new cosmology

    CERN Document Server

    Balbi, Amedeo

    2008-01-01

    The cosmic microwave background radiation is the afterglow of the big bang: a tenuous signal, more than 13 billion years old, which carries the answers to many of the questions about the nature of our Universe. It was serendipitously discovered in 1964, and thoroughly investigated in the last four decades by a large number of experiments. Two Nobel Prizes in Physics have already been awarded for research on the cosmic background radiation: one in 1978 to Arno Penzias and Robert Wilson, who first discovered it, the other in 2006, to George Smoot and John Mather, for the results of the COBE satellite. Most cosmological information is encoded in the cosmic background radiation by acoustic oscillations in the dense plasma that filled the primordial Universe: a "music" of the big bang, which cosmologists have long been trying to reconstruct and analyze, in order to distinguish different cosmological models, much like one can distinguish different musical instruments by their timbre and overtones. Only lately, this...

  14. The Cambridge-Cambridge X-ray Serendipity Survey: I X-ray luminous galaxies

    Science.gov (United States)

    Boyle, B. J.; Mcmahon, R. G.; Wilkes, B. J.; Elvis, M.

    1994-01-01

    We report on the first results obtained from a new optical identification program of 123 faint X-ray sources with S(0.5-2 keV) greater than 2 x 10(exp -14) erg/s/sq cm serendipitously detected in ROSAT PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSO's, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (10(exp 42) less than L(sub X) less than 10(exp 43.5) erg/s). Subsequent spectroscopy reveals them to be a mixture of star-burst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the Einstein Extended Medium Sensitivity Survey, these X-ray luminous galaxies exhibit a rate of cosmological evolution, L(sub X) varies as (1 + z)(exp 2.5 +/- 1.0), consistent with that derived for X-ray QSO's. This evolution, coupled with the steep slope determined for the faint end of the X-ray luminosity function (Phi(L(sub X)) varies as L(sub X)(exp -1.9)), implies that such objects could comprise 15-35% of the soft (1-2 keV) X-ray background.

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... clothing that might interfere with the x-ray images. Women should always inform their physician and x-ray ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air ...

  17. Laboratory astrophysics and microanalysis with NTD-germanium-based X-ray microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Silver, E.; Schnopper, H.; Bandler, S.; Murray, S.; Madden, N.; Landis, D.; Beeman, J.; Haller, E.; Barbera, M.; Tucker, G.; Gillaspy, J.; Takacs, E.; Porto, J

    2000-04-07

    With the ability to create cosmic plasma conditions in the laboratory it is possible to investigate the dependencies of key diagnostic X-ray lines on density, temperature, and excitation conditions that exist in astrophysical sources with X-ray optics and a high-resolution X-ray microcalorimeter. The same instrumentation can be coupled to scanning electron microscopes or X-ray fluorescence probes to analyze the elemental and chemical composition of electronic, biological, geological and particulate materials. We describe how our microcalorimeter and X-ray optics provide significantly improved capabilities for laboratory astrophysics and microanalysis.

  18. Recent Results for AGN Observed by the Rossi X-Ray Timing Explorer

    Science.gov (United States)

    Madejski, G. M.; Done, C.; Zycki, P.

    2000-01-01

    The Rossi X-ray Timing Explorer (RXTE) has produced many excellent observations of active galaxies, providing the best sensitivity in the 10 - 20 keV range so far. This presentation reports selected RTXE data for AGN in the context of the currently popular models. One is the recent result for two Seyfert 1 galaxies, NGC 5548 and IC4329a: both show the "canonical" Seyfert I X-ray spectra, with an underlying power law, plus Gaussian iron K line and Compton reflection. Interestingly, in both cases, the profile of the Fe K line does not extend as far to the red as seen in the famous NCG-6-30-15, and this indicates that the regions where the Fe K lines originate in AGN are diverse. Independently, in both objects we see a strong spectral variability of the primary continua, which soften as the sources brighten. The second result is for the heavily absorbed Seyfert 2 NGC 4945. The RXTE data confirm the strong absorption corresponding to the optical depth to electron scattering of about 2, but also reveal rapid variability of the hard (8-30 keV) X-ray emission on a time scale of a day or less. This suggests that for NGC 4945, the putative parsec-size molecular torus cannot be both geometrically and optically thick, and implies that the Cosmic X-ray Background is unlikely to be made up primarily of AGN with geometry as inferred for this object.

  19. Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin

    CERN Document Server

    Miniati, Francesco; Di Matteo, Tiziana

    2007-01-01

    Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter from a few tens of arcmin to several degree scales, together with complementary GLAST observations of gamma-ray emission from galaxy clusters and the blazars luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.

  20. Focusing X-Ray Telescopes

    Science.gov (United States)

    O'Dell, Stephen; Brissenden, Roger; Davis, William; Elsner, Ronald; Elvis, Martin; Freeman, Mark; Gaetz, Terrance; Gorenstein, Paul; Gubarev, Mikhall; Jerlus, Diab; Juda, Michael; Kolodziejczak, Jeffrey; Murray, Stephen; Petre, Robert; Podgorski, William; Ramsey, Brian; Reid, Paul; Saha, Timo; Wolk, Scott; Troller-McKinstry, Susan; Weisskopf, Martin; Wilke, Rudeger; Zhang, William

    2010-01-01

    During the half-century history of x-ray astronomy, focusing x-ray telescopes, through increased effective area and finer angular resolution, have improved sensitivity by 8 orders of magnitude. Here, we review previous and current x-ray-telescope missions. Next, we describe the planned next-generation x-ray-astronomy facility, the International X-ray Observatory (IXO). We conclude with an overview of a concept for the next next-generation facility, Generation X. Its scientific objectives will require very large areas (about 10,000 sq m) of highly-nested, lightweight grazing-incidence mirrors, with exceptional (about 0.1-arcsec) resolution. Achieving this angular resolution with lightweight mirrors will likely require on-orbit adjustment of alignment and figure.