Constraining Primordial Non-Gaussianity With the Abundance of High Redshift Clusters

We show how observations of the evolution of the galaxy cluster number abundance can be used to constrain primordial non-Gaussianity in the universe. We carry out a maximum likelihood analysis incorporating a number of current datasets and accounting for a wide range of sources of systematic error. Under the assumption of Gaussianity, the current data prefer a universe with matter density $\Omega_m\simeq 0.3$ and are inconsistent with $\Omega_m=1$ at the $2\sigma$ level. If we assume $\Omega_m=1$, the predicted degree of cluster evolution is consistent with the data for non-Gaussian models where the primordial fluctuations have at least two times as many peaks of height $3\sigma$ or more as a Gaussian distribution does. These results are robust to almost all sources of systematic error considered: in particular, the $\Omega_m=1$ Gaussian case can only be reconciled with the data if a number of systematic effects conspire to modify the analysis in the right direction. Given an independent measurement of $\Omega_m$, the techniques described here represent a powerful tool with which to constrain non-Gaussianity in the primordial universe, independent of specific details of the non-Gaussian physics. We discuss the prospects and strategies for improving the constraints with future observations.Comment: Minor revisions to match published ApJ version, 14 pages emulateap

High Velocity Line Emission in the NLR of NGC 4151

Narrow-band imaging of the nuclear region of NGC 4151 with the Hubble Space Telescope is presented. The filter bandpasses isolate line emission in various high velocity ranges in several ions. Slitless and long-slit spectra of the region with the Space Telescope Imaging Spectrograph also indicate the locations of high velocity gas. These emission regions are faint and are interspersed among the bright emission clouds seen in direct images. They have radial velocities up to 1400 km/s relative to the nucleus, and are found in both approach and recession on both sides of the nucleus. This contrasts strongly with the bright emission line clouds which have been discussed previously as showing bidirectional outflow with velocities within 400 km/s of the nucleus. We discuss the possible connections of the high velocity material with the radio jet and the nuclear radiation.Comment: 12 pages plus 6 figures, to be published in A

Insecticide resistance in malaria vector mosquitoes at four localities in Ghana, West Africa

<p>Abstract</p> <p>Background</p> <p>Malaria vector control programmes that rely on insecticide-based interventions such as indoor house spraying with residual insecticides or insecticide treated bed nets, need to base their decision-making process on sound baseline data. More and more commercial entities in Africa, such as mining companies, are realising the value to staff productivity of controlling malaria transmission in their areas of operation.</p> <p>This paper presents baseline entomological data obtained during surveys conducted for four mining operations in Ghana, West Africa.</p> <p>Results</p> <p>The vast majority of the samples were identified as <it>Anopheles gambiae </it>S form with only a few M form specimens being identified from Tarkwa. <it>Plasmodium falciparum </it>infection rates ranged from 4.5 to 8.6% in <it>An. gambiae </it>and 1.81 to 8.06% in <it>An. funestus</it>. High survival rates on standard WHO bioassay tests were recorded for all insecticide classes except the organophosphates that showed reasonable mortality at all locations (i.e. > 90%). The West African <it>kdr </it>mutation was detected and showed high frequencies in all populations.</p> <p>Conclusions</p> <p>The data highlight the complexity of the situation prevailing in southern Ghana and the challenges facing the malaria vector control programmes in this region. Vector control programmes in Ghana need to carefully consider the resistance profiles of the local mosquito populations in order to base their resistance management strategies on sound scientific data.</p

HST STIS spectroscopy of the triple nucleus of M31: two nested disks in Keplerian rotation around a Supermassive Black Hole

We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra taken around the CaT lines at 8500 see only the red giants in the double bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness red nucleus. P2 has a K-type spectrum, but the embedded blue nucleus has an A-type spectrum with strong Balmer absorption lines. Given the small likelihood for stellar collisions, a 200 Myr old starburst appears to be the most plausible origin of the blue nucleus. In stellar population, size, and velocity dispersion, the blue nucleus is so different from P1 and P2 that we call it P3. The line-of-sight velocity distributions of the red stars in P1+P2 strengthen the support for Tremaine s eccentric disk model. The kinematics of P3 is consistent with a circular stellar disk in Keplerian rotation around a super-massive black hole with M_bh = 1.4 x 10^8 M_sun. The P3 and the P1+P2 disks rotate in the same sense and are almost coplanar. The observed velocity dispersion of P3 is due to blurred rotation and has a maximum value of sigma = 1183+-201 km/s. The observed peak rotation velocity of P3 is V = 618+-81 km/s at radius 0.05" = 0.19 pc corresponding to a circular rotation velocity at this radius of ~1700 km/s. Any dark star cluster alternative to a black hole must have a half-mass radius <= 0.03" = 0.11 pc. We show that this excludes clusters of brown dwarfs or dead stars on astrophysical grounds.Comment: Astrophysical Journal, Sep 20, 2005, 21 pages including 20 figure

Evidence of a Supermassive Black Hole in the Galaxy NGC 1023 from the Nuclear Stellar Dynamics

We analyze the nuclear stellar dynamics of the SB0 galaxy NGC 1023, utilizing observational data both from the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope and from the ground. The stellar kinematics measured from these long-slit spectra show rapid rotation (V = 70 km/s at a distance of 0.1 arcsec = 4.9 pc from the nucleus) and increasing velocity dispersion toward the nucleus (where sigma = 295 +/- 30 km/s). We model the observed stellar kinematics assuming an axisymmetric mass distribution with both two and three integrals of motion. Both modeling techniques point to the presence of a central dark compact mass (which presumably is a supermassive black hole) with confidence > 99%. The isotropic two-integral models yield a best-fitting black hole mass of (6.0 +/- 1.4) x 10^7 M_sun and mass-to-light ratio (M/L_V) of 5.38 +/- 0.08, and the goodness-of-fit (chi^2) is insensitive to reasonable values for the galaxy's inclination. The three-integral models, which non-parametrically fit the observed line-of-sight velocity distribution as a function of position in the galaxy, suggest a black hole mass of (3.9 +/- 0.4) x 10^7 M_sun and M/L_V of 5.56 +/- 0.02 (internal errors), and the edge-on models are vastly superior fits over models at other inclinations. The internal dynamics in NGC 1023 as suggested by our best-fit three-integral model shows that the velocity distribution function at the nucleus is tangentially anisotropic, suggesting the presence of a nuclear stellar disk. The nuclear line of sight velocity distribution has enhanced wings at velocities >= 600 km/s from systemic, suggesting that perhaps we have detected a group of stars very close to the central dark mass.Comment: 21 pages, 12 figures, accepted in the Astrophysical Journa

The Heavy Element Enrichment of Lyman alpha Clouds in the Virgo Supercluster

Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Instead, this probably indicates that the gas has been predominately enriched by Type II supernovae. Such enrichment is most plausibly provided by an unbound galactic wind, given the absence of galaxies within a projected distance of 100 kpc and the presence of galaxies capable of driving a wind at larger distances. We also constrain the metallicity and physical conditions of the Virgo absorber at z = 0.00337 based on detections of O VI and H I and an upper limit on C IV. If this absorber is collisionally ionized, the O VI/C IV limit requires T > 10^{5.3} K. For either collisional ionization or photoionization, we find that [O/H] > -2.0 at z = 0.00337.Comment: Final Ap.J. versio

Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set

When galaxies merge, the supermassive black holes in their centers may form binaries and, during the process of merger, emit low-frequency gravitational radiation in the process. In this paper we consider the galaxy 3C66B, which was used as the target of the first multi-messenger search for gravitational waves. Due to the observed periodicities present in the photometric and astrometric data of the source of the source, it has been theorized to contain a supermassive black hole binary. Its apparent 1.05-year orbital period would place the gravitational wave emission directly in the pulsar timing band. Since the first pulsar timing array study of 3C66B, revised models of the source have been published, and timing array sensitivities and techniques have improved dramatically. With these advances, we further constrain the chirp mass of the potential supermassive black hole binary in 3C66B to less than $(1.65\pm0.02) \times 10^9~{M_\odot}$ using data from the NANOGrav 11-year data set. This upper limit provides a factor of 1.6 improvement over previous limits, and a factor of 4.3 over the first search done. Nevertheless, the most recent orbital model for the source is still consistent with our limit from pulsar timing array data. In addition, we are able to quantify the improvement made by the inclusion of source properties gleaned from electromagnetic data to `blind' pulsar timing array searches. With these methods, it is apparent that it is not necessary to obtain exact a priori knowledge of the period of a binary to gain meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap