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Predicting the Redshift 2 H-Alpha Luminosity Function Using [OIII] Emission Line Galaxies
Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure Baryonic Acoustic Oscillations (BAOs) in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the WFC3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of H-alpha emitters observable by these future surveys. WISP is an ongoing Hubble Space Telescope slitless spectroscopic survey, covering the 0.8 - 1.65 micrometers wavelength range and allowing the detection of H-alpha emitters up to z approximately equal to 1.5 and [OIII] emitters to z approximately equal to 2.3. We derive the H-alpha-[OIII] bivariate line luminosity function for WISP galaxies at z approximately equal to 1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurement, and demonstrate how it can be used to derive the H-alpha luminosity function from exclusively fitting [OIII] data. Using the z approximately equal to 2 [OIII] line luminosity function, and assuming that the relation between H-alpha and [OIII] luminosity does not change significantly over the redshift range, we predict the H-alpha number counts at z approximately equal to 2 - the upper end of the redshift range of interest for the future surveys. For the redshift range 0.7 less than z less than 2, we expect approximately 3000 galaxies per sq deg for a flux limit of 3 x 10(exp −16) ergs per sec per sq cm (the proposed depth of Euclid galaxy redshift survey) and approximately 20,000 galaxies per sq deg for a flux limit of approximately 10(exp −16) ergs per sec per sq cm (the baseline depth of WFIRST galaxy redshift survey).
Observations of the high latitude far ultraviolet background in the 1040-1080 A band
Observations of the far ultraviolet background at high galactic latitudes in a band from 1040-1080 A were carried out with a rocket-borne 1 meter telescope and a 0.23 square degree field of view photometer. The photometer had a sharp cutoff shortward of 1040 A and a sensitivity at hydrogen Lyman alpha of a factor of 0.0001 below its sensitivity at 1060 A. A second photometer monitored geocoronal hydrogen Lyman alpha emission enabling an accurate evaluation of counts due to this background. The hydrogen Lyman alpha flux contributed only 17 percent of the total counts detected in the cosmic background detector. An upper limit to the emission in the 1040-1080 A band of 9700 photons per sq cm-s-sr-A is obtained. This upper limit is compared with previous measurements and theoretical predictions.
The particle background of the Rosat PSPC
In order to permit quantitative studies of the diffuse cosmic X-ray background and of extended X-ray sources, the particle induced background of the Roentgen Satellite, Rosat, Position Sensitive Proportional Counter (PSPC) is parameterized. Data collected during 210,000 s of PSPC operation have been analyzed and the temporal, spectral, and spatial distributions investigated. About 77 percent of the residual events originate within the detector while the remainder enter through the counter window. During typical conditions, the count rate of the residual events is well correlated with the Master Veto (MV) count rate. The spectrum of these events is well described by a flat component plus a soft power law and an Al K-alpha line at 1.5 keV. Also during typical conditions, the ratio between the power law and flat components remains constant to +/- 4 while the relative Al K-alpha contribution increases with increasing MV count rate. The distribution of the counts over the field of view is uniform except for a slight radial dependence and shadowing caused by blockage of the externally produced component by the window support structure.
Toward unbiased determination of the redshift evolution of Lyman-alpha forest clouds
The possibility of using D(sub A), the mean depression of a quasar spectrum due to Ly-alpha forest absorption, to study the number density evolution of the Ly-alpha forest clouds is examined in some detail. Current D(sub A) measurements are made against a continuum that is a power-law extrapolation from the continuum longward of Ly-alpha emission. Compared to the line-counting approach, the D(sub A)-method has the advantage that the D(sub A) measurements are not affected by line-blending effects. However, we find using low-redshift quasar spectra obtained with the Hubble Space Telescope (HST), where the true continuum in the Ly-alpha forest can be estimated fairly reliably because of the much lower density of the Ly-alpha forest lines, that the extrapolated continuum often deviates systematically from the true continuum in the forest region. Such systematic continuum errors introduce large errors in the D(sub A) measurements. The current D(sub A) measurements may also be significantly biased by the possible presence of the Gunn-Peterson absorption. We propose a modification to the existing D(sub A)-method, namely, to measure D(sub A) against a locally established continuum in the Ly-alpha forest. Under conditions that the quasar spectrum has good resolution and S/N to allow for a reliable estimate of the local continuum in the Ly-alpha forest, the modified D(sub A) measurements should be largely free of the systematic uncertainties suffered by the existing D(sub A) measurements. We also introduce a formalism based on the work of Zuo (1993) to simplify the application of the D(sub A)-method(s) to real data. We discuss the merits and limitations of the modified D(sub A)-method, and conclude that it is a useful alternative. Our findings that the extrapolated continuum from longward of Ly-alpha emission often deviates systematically from the true continuum in the Ly-alpha forest present a major problem in the study of the Gunn-Peterson absorption.
Development of a direct experimental test for any violation of the equivalence principle by the weak interaction
Violation of the equivalence principle by the weak interaction is tested. Any variation of the weak interaction coupling constant with gravitational potential, i.e., a spatial variation of the fundamental constants is investigated. The level of sensitivity required for such a measurement is estimated on the basis of the size of a change in the gravitational potential which is accessible. The alpha particle spectrum is analyzed, and the counting rate was improved by a factor of approximately 100.
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission
The WMAP mission has mapped the full sky to determine the geometry, content, and evolution of the universe. Full sky maps are made in five microwave frequency bands to separate the temperature anisotropy of the cosmic microwave background (CMB) from foreground emission, including diffuse Galactic emission and Galactic and extragalactic point sources. We define masks that excise regions of high foreground emission, so CMB analyses can became out with minimal foreground contamination. We also present maps and spectra of the individual emission components, leading to an improved understanding of Galactic astrophysical processes. The effectiveness of template fits to remove foreground emission from the WMAP data is also examined. These efforts result in a CMB map with minimal contamination and a demonstration that the WMAP CMB power spectrum is insensitive to residual foreground emission. We use a Maximum Entropy Method to construct a model of the Galactic emission components. The observed total Galactic emission matches the model to less than 1% and the individual model components are accurate to a few percent. We find that the Milky Way resembles other normal spiral galaxies between 408 MHz and 23 GHz, with a synchrotron spectral index that is flattest (beta(sub s) approx. -2.5) near star-forming regions, especially in the plane, and steepest (beta(sub s) approx. -3) in the halo. This is consistent with a picture of relativistic cosmic ray electron generation in star-forming regions and diffusion and convection within the plane. The significant synchrotron index steepening out of the plane suggests a diffusion process in which the halo electrons are trapped in the Galactic potential long enough to suffer synchrotron and inverse Compton energy losses and hence a spectral steepening. The synchrotron index is steeper in the WMAP bands than in lower frequency radio surveys, with a spectral break near 20 GHz to beta(sub s) less than -3. The modeled thermal dust spectral index is also steep in the WMAP bands, with beta(sub d) approx. = 2.2. Our model is driven to these conclusions by the low level of total foreground contamination at approx. 60 GHz. Microwave and Ha measurements of the ionized gas agree well with one another at about the expected levels. Spinning dust emission is limited to less than 5% of the Ka-band foreground emission. A catalog of 208 point sources is presented. The reliability of the catalog is 98%, i.e., we expect five of the 208 sources to be statistically spurious. The mean spectral index of the point sources is alpha approx. 0(beta approx. -2). Derived source counts suggest a contribution to the anisotropy power from unresolved sources of (15.0 +/- 1.4) x 10(exp -3)micro sq K sr at Q-band and negligible levels at V-band and W-band. The Sunyaev-Zeldovich effect is shown to be a negligible "contamination" to the maps.
Application of the Space-Time Conservation Element and Solution Element Method to One-Dimensional Convection-Diffusion Problems
In the space-time conservation element and solution element (CE/SE) method, the independent marching variables used comprise not only the mesh value of the physical dependent variables but also, in contrast to it typical numerical method, the Mesh values of the spatial derivatives of the physical variables The use of the extra marching variables results from the need to construct the two-level explicit and nondissipative schemes which are at the core of the CE/SE development. It also results from the need to minimize the stencil while maintaining accuracy. In this paper using the 1D(sub (alpha)-mu) scheme as an example, the effect of this added complication on consistency, accuracy and operation count is assessed. As part of this effort, an equivalent yet more efficient form of the alpha-mu scheme in which the independent marching variables are the local fluxes tied to each mesh point is introduced. Also, the intriguing relations that exist among the alpha-mu. Leapfrog, and DuFort-Frankel schemes are further explored. In addition, the redundance of the Leapfrog, DUFort-Frankel, and Lax scheme and the remedy for this redundance are discussed. This paper is concluded with the construction and evaluation of a CE/SE solver for the inviscid Burger equation.
Detection of a very bright source close to the LMC supernova SN 1987A
High angular resolution observations of the supernova in the Large Magellanic Cloud, SN 1987A, have revealed a bright source separated from the SN by approximately 60 mas with a magnitude difference of 2.7 at 656 nm (H-alpha). Speckle imaging techniques were applied to data recorded with the CfA two-dimensional photon counting detector on the CTIO 4 m telescope on March 25 and April 2 to allow measurements in H-alpha on both nights and at 533 nm and 450 nm on the second night. The nature of this object is as yet unknown, though it is almost certainly a phenomenon related to the SN.
A statistical study of spicule inclinations
The apparent angles of more than 5000 quiet region spicules situated at various position angles around the sun's limb have been measured on off-band H-alpha filtergrams taken during the years 1972-1975. The counts were made exclusively in projection on the disk, within 5.25 deg of the limb. The tendency of the average spicule to lean towards or away from the pole is small at most, and at no latitude exceeds 8 deg. The spread in angles is 30-35 deg.
Observation of upflows during soft X-ray solar flares
Upflows of the soft X-ray emission regions of four flares located near sun center have been determined from the blueshift of the absolute wavelength of the Ca XIX resonance lines recorded by the SOLFLEX spectrometer on the P-78 spacecraft. Peak upward velocities were 35-90 km/s and occurred during the time of gradual increase in the Ca XIX count rate and prior to the peak H-alpha emission. Rises in altitude of 7000-80,000 km were inferred from the upward velocities.
GRO J2058+42 Observations with Chandra and Discovery of a Likely Optical Counterpart
GRO J2058+42 is a 195 s transient X-ray pulsar discovered in 1995 with BATSE. In 1996, RXTE located GRO J2058+42 to a 90% confidence error circle with a 4' radius. On 20 February 2004, the region including the error circle was observed with Chandra ACIS-I. No X-ray sources were detected within the error circle, however, 2 faint sources were det.ected in the ACISI field-of-view. We obtained optical observations of the brightest object that had about 64 X-ray counts and was just 0.3' outside the error circle. The optical spectrum contained a strong H alpha line and corresponds to an infrared object in the 2MASS catalog, indicating a Be/X-ray system. Although X-ray pulsations were undetectable due to the low count rate, our evidence is strong that this object is the optical counterpart to GRO J2058+42. We present results from the Chandra observation and from the optical observations.
GRO J2058+42 Observations with Chandra and Detection of a Likely Optical Counterpart
GRO J2058+42 is a 195-s transient X-ray pulsar discovered in 1995 with BATSE. In 1996, RXTE located GRO J2058+42 to a 90% confidence error circle with a 4-arcminute radius. On 20 February 2004, the region including the error circle was observed with Chandra ACIS-I. No X-ray sources were detected within the error circle, however, 2 faint sources were detected in the ACIS-I field-of-view. We obtained follow-up optical observations of the brightest object, that had about 64 X-ray counts and was just 0.3 arcmin outside the error circle. The optical spectrum contained a strong H-alpha line and corresponds to an infrared object in the 2MASS catalog, indicating a Be/X-ray system. Although X-ray pulsations were undetectable due to the low count rate, this object is most likely the optical counterpart to GRO J2058+42. We present results from the Chandra observation and from the optical observations.
A study of solar flare electron events from October 1972 through December 1974 from Imp 7 and 8
Data from the Johns Hopkins University Applied Physics Laboratory Charged Particle Measurement Experiment aboard Imp H and J were searched for solar flare produced intensity increases in greater than 0.2-MeV electrons during the 26-month period from October 1972 through December 1974. Of the 44 solar electron events found during this period, 31 were isolated for a detailed statistical study. Systematics among the characteristics of the electron profiles (e.g., peak intensity times and count rates) and those of the associated flares (e.g., H-alpha onset times, H-alpha importance class, heliocentric coordinates, etc.) were examined, and the significant results are presented in several scatter plots. The results reveal that the time delay between the flare onset and the arrival of the peak electron intensity at 1 AU (time to maximum) is a function of the flare's deviation in heliolongitude from the solar region which was well connected to the earth via a magnetic flux tube; the well-connected flares produced electron intensity maxima in the least time.
Adaptation of the TH Epsilon Mu formalism for the analysis of the equivalence principle in the presence of the weak and electroweak interaction
The TH epsilon mu formalism, used in analyzing equivalence principle experiments of metric and nonmetric gravity theories, is adapted to the description of the electroweak interaction using the Weinberg-Salam unified SU(2) x U(1) model. The use of the TH epsilon mu formalism is thereby extended to the weak interactions, showing how the gravitational field affects W sub mu (+ or -1) and Z sub mu (0) boson propagation and the rates of interactions mediated by them. The possibility of a similar extension to the strong interactions via SU(5) grand unified theories is briefly discussed. Also, using the effects of the potentials on the baryon and lepton wave functions, the effects of gravity on transition mediated in high-A atoms which are electromagnetically forbidden. Three possible experiments to test the equivalence principle in the presence of the weak interactions, which are technologically feasible, are then briefly outline: (1) K-capture by the FE nucleus (counting the emitted X-ray); (2) forbidden absorption transitions in high-A atoms' vapor; and (3) counting the relative Beta-decay rates in a suitable alpha-beta decay chain, assuming the strong interactions obey the equivalence principle.
SOHO Ultraviolet Coronagraph Spectrometer (UVCS) Mission Operations and Data Analysis
The scientific goal of UVCS is to obtain detailed empirical descriptions of the extended solar corona as it evolves over the solar cycle and to use these descriptions to identify and understand the physical processes responsible for coronal heating, solar wind acceleration, coronal mass ejections (CMEs), and the phenomena that establish the plasma properties of the solar wind as measured by "in situ" solar wind instruments. This report covers the period from 15 November 1998 to 14 March 2001. During that time, UVCS observations have consisted of three types: 1) standard synoptic observations comprising, primarily, the H I Lycc line profile and the O VI 103.2 and 103.7 nm intensity over a range of heights from 1.5 to about 3.0 solar radii and covering 360 degrees about the sun, 2) sit and stare watches for CMEs, and 3) special observations designed by the UVCS Lead Observer of the Week for a specific scientific purpose. The special observations are often coordinated with those of other space-based and ground based instruments and they often are part of SOHO joint observation programs and campaigns. Lead observers have included UVCS Co-Investigators, Guest Investigators, scientists from the solar physics community and several graduate and undergraduate level students. UVCS has continued to successfully meet its goal of using powerful spectroscopic diagnostic techniques to obtain a much more detailed description of coronal structures than existed before the SOHO mission. The new descriptions of coronal structures from UVCS have inspired a large number of theoretical studies aimed at identifying the physical processes responsible for solar wind acceleration in coronal holes and streamers. UVCS has proven to be a very stable instrument. Stellar observations have demonstrated its stability and the analysis of coordinated observations with Spartan 201 have verified the accuracy of the absolute calibration and spectral resolution at H I Ly (alpha) line profile. UVCS has required no flight software modifications and all mechanisms are operational. The UVCS O VI Channel with its redundant optical path for wavelengths near H I Ly (alpha) is capable of observing the entire UVCS wavelength range. Since December 1998, the O VI Channel has been used for all UVCS observations. Although the H I Ly (alpha) Channel and detector are still operational, increases in the dark count up to about 5x 10(exp-4) counts/sec/pixel and an increase in high voltage current to within a factor of two of the maximum used in the laboratory before flight led to the decision to not use that detector at the present time. There is no significant science impact since the O VI Channel can observe nearly the same wavelength range.
SOHO Ultraviolet Coronagraph Spectrometer (UVCS) Mission Operations and Data Analysis
The scientific goal of UVCS is to obtain detailed empirical descriptions of the extended solar corona as it evolves over the solar cycle and to use these descriptions to identify and understand the physical processes responsible for coronal heating, solar wind acceleration, coronal mass ejections (CMEs), and the phenomena that establish the plasma properties of the solar wind as measured by 'in situ' solar wind instruments. This report covers the period from 01 February 2002 to 15 February 2003. During that time, UVCS observations have consisted of three types: 1) standard synoptic observations comprising, primarily, the H I Ly alpha line profile and the O VI 103.2 and 103.7 nm intensity over a range of heights from 1.5 to about 3.0 solar radii and covering 360 degrees about the sun, 2) sit and stare watches for CMEs, and 3) special observations designed by the UVCS Lead Observer of the Week for a specific scientific purpose. The special observations are often coordinated with those of other space-based and ground-based instruments and they often are part of SOHO joint observation programs and campaigns. Lead observers have included UVCS Co-Investigators, scientists from the solar physics community and several graduate and undergraduate level students. UVCS has continued to achieve its purpose of using powerful spectroscopic diagnostic techniques to obtain a much more detailed description of coronal structures and dynamic phenomena than existed before the SOHO mission. The new descriptions of coronal mass ejections (CMEs) and coronal structures from UVCS have inspired a large number of theoretical studies aimed at identifying the physical processes responsible for CMEs and solar wind acceleration in coronal holes and streamers. UVCS has proven to be a very stable instrument. Stellar observations have demonstrated its stability. UVCS has required no flight software modifications and all mechanisms are operational. The UVCS O VI Channel with its redundant optical path for wavelengths near H I Ly alpha is capable of observing the entire UVCS wavelength range. Since December 1998, the O VI Channel has been used for all UVCS observations. Although the H I Ly alpha Channel and detector are still operational, increases in the dark count up to about 5 x 10(exp -4) counts/sec/pixel and an increase in high voltage current to within a factor of two of the maximum used in the laboratory before flight led to the decision to not use that detector at the present time. There is no significant decrease in the scientific capability of UVCS owing to the O VI channel redundant optical path. UVCS data, data analysis software, calibration files and the mission log are available from the SOHO archive and SAO. All UVCS data is now available to scientists and the general public via the SOHO Data Archive and SAO within three months of the observations. UVCS has resulted in 46 scientific papers in 2002. There were numerous presentations at scientific meetings. All requests for observation time by qualified outside users have been granted.