Reproduction, growth and development in two contiguously allopatric rodent species, genus Scotinomys

http://deepblue.lib.umich.edu/bitstream/2027.42/56395/1/MP151.pd

Two photon annihilation of Kaluza-Klein dark matter

We investigate the fermionic one-loop cross section for the two photon annihilation of Kaluza-Klein (KK) dark matter particles in a model of universal extra dimensions (UED). This process gives a nearly mono-energetic gamma-ray line with energy equal to the KK dark matter particle mass. We find that the cross section is large enough that if a continuum signature is detected, the energy distribution of gamma-rays should end at the particle mass with a peak that is visible for an energy resolution of the detector at the percent level. This would give an unmistakable signature of a dark matter origin of the gamma-rays, and a unique determination of the dark matter particle mass, which in the case studied should be around 800 GeV. Unlike the situation for supersymmetric models where the two-gamma peak may or may not be visible depending on parameters, this feature seems to be quite robust in UED models, and should be similar in other models where annihilation into fermions is not helicity suppressed. The observability of the signal still depends on largely unknown astrophysical parameters related to the structure of the dark matter halo. If the dark matter near the galactic center is adiabatically contracted by the central star cluster, or if the dark matter halo has substructure surviving tidal effects, prospects for detection look promising.Comment: 17 pages, 3 figures; slightly revised versio

Kaluza-Klein Dark Matter, Electrons and Gamma Ray Telescopes

Kaluza-Klein dark matter particles can annihilate efficiently into electron-positron pairs, providing a discrete feature (a sharp edge) in the cosmic $e^+ e^-$ spectrum at an energy equal to the particle's mass (typically several hundred GeV to one TeV). Although this feature is probably beyond the reach of satellite or balloon-based cosmic ray experiments (those that distinguish the charge and mass of the primary particle), gamma ray telescopes may provide an alternative detection method. Designed to observe very high-energy gamma-rays, ACTs also observe the diffuse flux of electron-induced electromagnetic showers. The GLAST satellite, designed for gamma ray astronomy, will also observe any high energy showers (several hundred GeV and above) in its calorimeter. We show that high-significance detections of an electron-positron feature from Kaluza-Klein dark matter annihilations are possible with GLAST, and also with ACTs such as HESS, VERITAS or MAGIC.Comment: 10 pages, 2 figure

The Chandra X-ray Observatory Resolves the X-ray Morphology and Spectra of a Jet in PKS 0637-752

The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) of about 100ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0.4 arcsec, reveals a jet that extends about 10 arcsec to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band (Tingay et al. 1998) had identified a kpc-scale radio jet extending to the West of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9 arcsec, after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log Lx ~ 45.8 erg/s (2 - 10keV), and appears not to have changed since it was observed with ASCA in November 1996. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the non-existence of emission lines recently reported in the ASCA observations of PKS 0637-752, and briefly discuss plausible X-ray emission mechanisms.Comment: 24 pages, includes 8 figures, Accepted for publication in Ap

A Brief Review on Dark Matter Annihilation Explanation for e±e^\pm Excesses in Cosmic Ray

Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are $e^{\pm}$ excesses in the cosmic ray energy spectrum. PAMELA observed excesses only in $e^+$, but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS observed excesses in $e^++e^-$ spectrum, but the detailed shapes are different which requires future experimental observations to pin down the correct data set. Nevertheless a lot of efforts have been made to explain the observed $e^\pm$ excesses, and also why PAMELA only observed excesses in $e^+$ but not in anti-proton. In this brief review we discuss one of the most popular mechanisms to explain the data, the dark matter annihilation. It has long been known that about 23% of our universe is made of relic dark matter. If the relic dark matter was thermally produced, the annihilation rate is constrained resulting in the need of a large boost factor to explain the data. We will discuss in detail how a large boost factor can be obtained by the Sommerfeld and Briet-Wigner enhancement mechanisms. Some implications for particle physics model buildings will also be discussed.Comment: 22 pages, 6 figures. Several typoes corrected and some references added. Published in Mod. Phys. Lett. A, Vol. 24, No. 27 (2009) pp. 2139-216

Affinities of the family Sollasellidae (Porifera, Demospongiae). I. Morphological evidence

Comparison of Sollasella digitata Lendenfeld, 1888, up until the present assigned to its own family Sollasellidae Lendenfeld, 1887 in the order Hadromerida, and Raspailopsis cervicornis Burton, 1959, assigned to Raspailiidae Nardo, 1833 in the order Poecilosclerida, leads to the conclusion that both should be considered congeneric and are best assigned to a single genus Sollasella. This conclusion is based on examination of habit and skeletal characters of the type material of S. digitata and both type and freshly collected material of S. cervicornis. The conclusion is strengthened by the discovery of a new species, Sollasella moretonensis n.sp. collected in North Australia (primarily in the northeastern coast, but also an isolated record from the northwestern Australian coast), which possesses in addition to the characteristic surface pattern and skeletal structure, genuine echinating acanthostyles. The redefined genus Sollasella shares axial / extra-axial arrangement of the skeleton, special surface brushes of oxeas surrounding a single protruding style, and vestigial occurrence of acanthostyles with many Raspailia s.l. Nevertheless, it is retained as a separate genus, on account of its peculiar polygonal arrangement of surface pores. The distribution of the genus is disjunctive including both (southeast, northeast and northwest) Australian and Western Indian Ocean localities, but so far no intermediate records. Based on this morphological evidence, it is proposed – pending publication of corroborating molecular evidence to be presented in a follow-up study – to reassign Sollasella and the family Sollasellidae to the poecilosclerid family Raspailiidae

OnTheFly: a tool for automated document-based text annotation, data linking and network generation

OnTheFly is a web-based application that applies biological named entity recognition to enrich Microsoft Office, PDF and plain text documents. The input files are converted into the HTML format and then sent to the Reflect tagging server, which highlights biological entity names like genes, proteins and chemicals, and attaches to them JavaScript code to invoke a summary pop-up window. The window provides an overview of relevant information about the entity, such as a protein description, the domain composition, a link to the 3D structure and links to other relevant online resources. OnTheFly is also able to extract the bioentities mentioned in a set of files and to produce a graphical representation of the networks of the known and predicted associations of these entities by retrieving the information from the STITCH database

Chandra Discovery of a 100 kpc X-ray Jet in PKS 0637--752

The quasar PKS 0637-753, the first celestial X-ray target of the Chandra X-ray Observatory, has revealed asymmetric X-ray structure extending from 3 to 12 arcsec west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z=0.651, the jet is the largest (~100 kpc) and most luminous (~10^{44.6} ergs/s) of the few so far detected in X-rays. This letter presents a high resolution X-ray image of the jet, from 42 ks of data when PKS 0637-753 was on-axis and ACIS-S was near the optimum focus. For the inner portion of the radio jet, the X-ray morphology closely matches that of new ATCA radio images at 4.8 and 8.6 GHz. Observations of the parsec scale core using the VSOP space VLBI mission show structure aligned with the X-ray jet, placing important constraints on the X-ray source models. HST images show that there are three small knots coincident with the peak radio and X-ray emission. Two of these are resolved, which we use to estimate the sizes of the X-ray and radio knots. The outer portion of the radio jet, and a radio component to the east, show no X-ray emission to a limit of about 100 times lower flux. The X-ray emission is difficult to explain with models that successfully account for extra-nuclear X-ray/radio structures in other active galaxies. We think the most plausible is a synchrotron self-Compton (SSC) model, but this would imply extreme departures from the conventional minimum-energy and/or homogeneity assumptions. We also rule out synchrotron or thermal bremsstrahlung models for the jet X-rays, unless multicomponent or ad hoc geometries are invoked.Comment: 5 Pages, 2 Figures. Submitted to Ap. J. Letter

Elastic Scattering and Direct Detection of Kaluza-Klein Dark Matter

Recently a new dark matter candidate has been proposed as a consequence of universal compact extra dimensions. It was found that to account for cosmological observations, the masses of the first Kaluza-Klein modes (and thus the approximate size of the extra dimension) should be in the range 600-1200 GeV when the lightest Kaluza-Klein particle (LKP) corresponds to the hypercharge boson and in the range 1 - 1.8 TeV when it corresponds to a neutrino. In this article, we compute the elastic scattering cross sections between Kaluza-Klein dark matter and nuclei both when the lightest Kaluza-Klein particle is a KK mode of a weak gauge boson, and when it is a neutrino. We include nuclear form factor effects which are important to take into account due to the large LKP masses favored by estimates of the relic density. We present both differential and integrated rates for present and proposed Germanium, NaI and Xenon detectors. Observable rates at current detectors are typically less than one event per year, but the next generation of detectors can probe a significant fraction of the relevant parameter space.Comment: 23 pages, 11 figures; v2,v3: Ref. added, discussion improved, conclusions unchanged. v4: Introduction was expanded to be more appropriate for non experts. Various clarifications added in the text. Version to be published in New Journal of Physic

ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)

We present ASCA observations of the radio-selected BL Lacertae objects 1749+096 (z=0.32) and 2200+420 (BL Lac, z=0.069) performed in 1995 Sept and Nov, respectively. The ASCA spectra of both sources can be described as a first approximation by a power law with photon index Gamma ~ 2. This is flatter than for most X-ray-selected BL Lacs observed with ASCA, in agreement with the predictions of current blazar unification models. While 1749+096 exhibits tentative evidence for spectral flattening at low energies, a concave continuum is detected for 2200+420: the steep low-energy component is consistent the high-energy tail of the synchrotron emission responsible for the longer wavelengths, while the harder tail at higher energies is the onset of the Compton component. The spectral energy distributions from radio to gamma-rays are consistent with synchrotron-self Compton emission from a single homogeneous region shortward of the IR/optical wavelengths, with a second component in the radio domain related to a more extended emission region. For 2200+420, comparing the 1995 Nov state with the optical/GeV flare of 1997 July, we find that models requiring inverse Compton scattering of external photons provide a viable mechanism for the production of the highest (GeV) energies during the flare. An increase of the external radiation density and of the power injected in the jet can reproduce the flat gamma-ray continuum observed in 1997 July. A directly testable prediction of this model is that the line luminosity in 2200+420 should vary shortly after (~1 month) a non-thermal synchrotron flare.Comment: 28 pages,6 figures, 5 tables; LaTeX document. accepted for publication in the Astrophysical Journa