Green Manures or Fertilizer Nitrogen for Corn?

How much nitrogen does a legume green-manure crop contribute to the soil? What influence does it have on the yields of the following corn crop? How does this compare with side-dressed applications of fertilizer nitrogen

Modeling magnetic disk wind state transitions in black hole X-Ray binaries

We analyze three prototypical black hole X-ray binaries, 4U 1630-472, GRO J1655-40, and H1743-322, in an effort to systematically understand the intrinsic state transition of the observed accretion disk winds between wind-on and wind-off states by utilizing state-of-the-art Chandra/HETGS archival data from multi-epoch observations. We apply our magnetically driven wind models in the context of magnetohydrodynamic (MHD) calculations to constrain (1) their global density slope (p), (2) their density (n (17)) at the foot point of the innermost launching radius, and (3) the abundances of heavier elements (A (Fe,S,Si)). Incorporating the MHD winds into xstar photoionization calculations in a self-consistent manner, we create a library of synthetic absorption spectra given the observed X-ray continua. Our analysis clearly indicates a characteristic bimodal transition of multi-ion X-ray winds; i.e., the wind density gradient is found to steepen (from p similar to 1.2-1.4 to similar to 1.4-1.5) while its density normalization declines as the source transitions from the wind-on to the wind-off state. The model implies that the ionized wind remains physically present even in the wind-off state, despite its apparent absence in the observed spectra. Supersolar abundances for heavier elements are also favored. Our global multi-ion wind models, taking into account soft X-ray ions as well as Fe K absorbers, show that the internal wind condition plays an important role in wind transitions besides photoionization changes. Simulated XRISM/Resolve and Athena/X-IFU spectra are presented to demonstrate a high fidelity of the multi-ion wind model for a better understanding of these powerful ionized winds in the coming decades

Multi-Wavelength Monitoring of GRS 1915+105

Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8m Perkins telescope at Lowell Observatory. The first long-term well-sampled IR light curve of GRS 1915+105 is presented herein and is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities

The Concordance Cosmic Star Formation Rate: Implications from and for the Supernova Neutrino and Gamma Ray Backgrounds

We constrain the Cosmic Star Formation Rate (CSFR) by requiring that massive stars produce the observed UV, optical, and IR light while at the same time not overproduce the Diffuse Supernova Neutrino Background as bounded by Super-Kamiokande. With the massive star component so constrained we then show that a reasonable choice of stellar Initial Mass Function and other parameters results in SNIa rates and iron yields in good agreement with data. In this way we define a `concordance' CSFR that predicts the optical SNII rate and the SNIa contribution to the MeV Cosmic Gamma-Ray Background. The CSFR constrained to reproduce these and other proxies of intermediate and massive star formation is more clearly delineated than if it were measured by any one technique and has the following testable consequences: (1) SNIa contribute only a small fraction of the MeV Cosmic Gamma-Ray Background, (2) massive star core-collapse is nearly always accompanied by a successful optical SNII, and (3) the Diffuse Supernova Neutrino Background is tantalizingly close to detectability.Comment: Improved discussion. Version accepted for publication in JCA

Positron Annihilation in the Galaxy

The 511 keV line from positron annihilation in the Galaxy was the first γ-ray line detected to originate from outside our solar system. Going into the fifth decade since the discovery, the source of positrons is still unconfirmed and remains one of the enduring mysteries in γ-ray astronomy. With a large flux of ∼10−3 γ/cm2/s, after 15 years in operation INTEGRAL/SPI has detected the 511 keV line at >50σ and has performed high-resolution spectral studies which conclude that Galactic positrons predominantly annihilate at low energies in warm phases of the interstellar medium. The results from imaging are less certain, but show a spatial distribution with a strong concentration in the center of the Galaxy. The observed emission from the Galactic disk has low surface brightness and the scale height is poorly constrained, therefore, the shear number of annihilating positrons in our Galaxy is still not well know. Positrons produced in β+-decay of nucleosynthesis products, such as 26Al, can account for some of the annihilation emission in the disk, but the observed spatial distribution, in particular the excess in the Galactic bulge, remains difficult to explain. Additionally, one of the largest uncertainties in these studies is the unknown distance that positrons propagate before annihilation. In this paper, we will summarize the current knowledge base of Galactic positrons, and discuss how next-generation instruments could finally provide the answers.Non peer reviewedFinal Accepted Versio

Integral results on GRB030320: a long gamma-ray burst detected at the edge of the field of view

GRB030320 is the 5th Gamma-ray burst (GRB) detected by INTEGRAL in the field of view (FoV). It is so far the GRB with the largest off-axis angle with respect to the INTEGRAL pointing direction, near to the edge of the FoV of both main instruments, IBIS and SPI. Nevertheless, it was possible to determine its position and to extract spectra and fluxes. The GRB nature of the event was confirmed by an IPN triangulation. It is a ~ 60 s long GRB with two prominent peaks separated by ~ 35 s. The spectral shape of the GRB is best represented by a single power law with a photon index Gamma ~ 1.7. The peak flux in the 20 - 200 keV band is determined to ~ 5.7 photons cm-2 s-1 and the GRB fluence to 1.1 x 10-5 erg cm-2. Analysing the spectral evolution of the GRB, a ``hard-to-soft'' behaviour emerges. A search for an optical counterpart has been carried out, but none was found.Comment: 5 pages, 3 figures. Accepted for publication in A&AL (INTEGRAL issue

Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991

We present a self-consistent model of accretion flows which unifies four distinct spectral states observed in black hole X-ray binaries: quiescent, low, intermediate and high states. In the quiescent, low and intermediate states, the flow consists of an inner hot advection-dominated part extending from the black hole horizon to a transition radius and an outer thin disk. In the high state the thin disk is present at all radii. The model is essentially parameter-free and treats consistently the dynamics of the accretion flow, the thermal balance of the ions and electrons, and the radiation processes in the accreting gas. With increasing mass accretion rate, the model goes through a sequence of stages for which the computed spectra resemble very well observations of the four spectral states; in particular, the low-to-high state transition observed in black hole binaries is naturally explained as resulting from a decrease in the transition radius. We also make a tentative proposal for the very high state, but this aspect of the model is less secure. We test the model against observations of the soft X-ray transient Nova Muscae during its 1991 outburst. The model reproduces the observed lightcurves and spectra surprisingly well, and makes a number of predictions which can be tested with future observations.Comment: 68 pages, LaTeX, includes 1 table (forgotten in the previous version) and 14 figures; submitted to The Astrophysical Journa

The Burst and Transient Source Experiment (BATSE) Earth Occultation Catalog of Low-Energy Gamma-Ray Sources

The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the low-energy gamma-ray sky (20-1000 keV) between 1991 April and 2000 May (9.1y). Using the Earth Occultation Technique to extract flux information, a catalog of sources using data from the BATSE large area detectors has been prepared. The first part of the catalog consists of results from the monitoring of 58 sources, mostly Galactic. For these sources, we have included tables of flux and spectral data, and outburst times for transients. Light curves (or flux histories) have been placed on the world wide web. We then performed a deep-sampling of 179 objects (including the aforementioned 58 objects) combining data from the entire 9.1y BATSE dataset. Source types considered were primarily accreting binaries, but a small number of representative active galaxies, X-ray-emitting stars, and supernova remnants were also included. The deep sample results include definite detections of 83 objects and possible detections of 36 additional objects. The definite detections spanned three classes of sources: accreting black hole and neutron star binaries, active galaxies and supernova remnants. Flux data for the deep sample are presented in four energy bands: 20-40, 40-70, 70-160, and 160-430 keV. The limiting average flux level (9.1 y) for the sample varies from 3.5 to 20 mCrab (5 sigma) between 20 and 430 keV, depending on systematic error, which in turn is primarily dependent on the sky location. To strengthen the credibility of detection of weaker sources (5-25 mCrab), we generated Earth occultation images, searched for periodic behavior using FFT and epoch folding methods, and critically evaluated the energy-dependent emission in the four flux bands.Comment: 64 pages, 17 figures, abstract abridged, Accepted by ApJ

Autonomy of Nations and Indigenous Peoples and the Environmental Release of Genetically Engineered Animals with Gene Drives

This article contends that the environmental release of genetically engineered (GE) animals with heritable traits that are patented will present a challenge to the efforts of nations and indigenous peoples to engage in self‐determination. The environmental release of such animals has been proposed on the grounds that they could function as public health tools or as solutions to the problem of agricultural insect pests. This article brings into focus two political‐economic‐legal problems that would arise with the environmental release of such organisms. To address those challenges, it is proposed that nations considering the environmental release of GE animals must take into account the underlying circumstances and policy failures that motivate arguments for the use of the modified animals. Moreover, countries must recognize that the UN International Covenant on Civil and Political Rights and the UN International Covenant on Economic, Social and Cultural Rights place on them an obligation to ensure that GE animals with patented heritable traits are not released without the substantive consent of the nations or indigenous peoples that could be affected

Fermi Large Area Telescope Bright Gamma-ray Source List

Following its launch in June 2008, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in 3 months produced a deeper and better-resolved map of the gamma-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than ~10-sigma) gamma-ray sources in these data. These are the best-characterized and best-localized point-like (i.e., spatially unresolved) gamma-ray sources in the early-mission data.Comment: Accepted by ApJS. Many helpful comments by referee incorporated 57 pages, 12 figure