3,074 research outputs found
Preliminary galaxy extraction from DENIS images
The extragalactic applications of NIR surveys are summarized with a focus on
the ability to map the interstellar extinction of our Galaxy. Very preliminary
extraction of galaxies on a set of 180 consecutive images is presented, and the
results illustrate some of the pitfalls in attempting an homogeneous extraction
of galaxies from these wide-angle and shallow surveys.Comment: Invited talk at "The Impact of Large-Scale Near-IR Sky Surveys",
meeting held in Tenerife, Spain, April 1996. 10 pages LaTeX with style file
and 4 PS files include
Surface energy from order parameter profile: At the QCD phase transition
The order parameter profile between coexisting confined and plasma regions at the quantum chromodynamic (QCD) phase transition is constructed. The dimensionless combination of the surface energy (Sigma) and the correlation length (Zeta) is estimated to be Sigma Zeta 3 approximately equals 0.8
A statistical method to search for recoiling supermassive black holes in active galactic nuclei
We propose an observational test for gravitationally recoiling supermassive black holes (BHs) in active galactic nuclei, based on a
correlation between the velocities of BHs relative to their host galaxies, |Δv|, and their obscuring dust column densities, Σdust
(both measured along the line of sight). We use toy models for the distribution of recoil velocities, BH trajectories, and the
geometry of obscuring dust tori in galactic centres, to simulate 2.5 × 105 random observations of recoiling quasars. BHs with
recoil velocities comparable to the escape velocity from the galactic centre remain bound to the nucleus, and do not fully settle
back to the centre of the torus due to dynamical friction in a typical quasar lifetime. We find that |Δv| and Σdust for these BHs
are positively correlated. For obscured (Σdust > 0) and for partially obscured (0 < Σdust ≲ 2.3 g m−2) quasars with |Δv| ≥ 45 km
s−1, the sample correlation coefficient between log10(|Δv|) and Σdust is r45 = 0.28 ± 0.02 and r45 = 0.13 ± 0.02, respectively.
Allowing for random ± 100 km s− 1 errors in |Δv| unrelated to the recoil dilutes the correlation for the partially obscured
quasars to r45 = 0.026 ± 0.004 measured between |Δv| and Σdust. A random sample of ≳ 3500 obscured quasars with |Δv| ≥
45 km s−1 would allow rejection of the no-correlation hypothesis with 3σ significance 95 per cent of the time. Finally, we find
that the fraction of obscured quasars, obs (|Δv|), decreases with |Δv| from obs (103 km s−1) ≲ 0.4.
This predicted trend can be compared to the observed fraction of type II quasars, and can further test combinations of recoil,
trajectory, and dust torus models
Correlation between In Vivo and In Vitro Efficacy of Antimicrobial Agents against Foreign Body Infections
Implant-associated infections are often resistant to antibiotic therapy. Routine sensitivity tests fail to predict therapeutic success. Therefore experimental in vitro tests were sought that would better correlate with drug efficacy in device-related infections. The activity of six different antibiotics against methicillin-resistant Staphylococcus epidermidis was investigated. In vivo studies were performed with the guinea pig tissue-cage animal model; in vitro studies with minimum inhibiting and bactericidal concentrations, time-kill studies of growing and stationary-phase microorganisms, the killing of glass-adherent S. epidermidis. Drug efficacy on stationary and adherent microorganisms, but not minimum inhibiting concentrations, predicted the outcome of device-related infections. Rifampin cured 12 of 12 infections and was also the most efficient drug in any experimental in vitro test. Similarly, the failure of ciproftoxacin to eradicate foreign body infections correlated with its low efficacy on stationary-phase and adherent S. epidermidi
GLADE: A galaxy catalogue for multimessenger searches in the advanced gravitational-wave detector era
We introduce a value-added full-sky catalogue of galaxies, named as Galaxy List for the Advanced Detector Era, or GLADE. The purpose of this catalogue is to (i) help identifications of host candidates for gravitational-wave events, (ii) support target selections for electromagnetic follow-up observations of gravitational-wave candidates, (iii) provide input data on the matter distribution of the local Universe for astrophysical or cosmological simulations, and (iv) help identifications of host candidates for poorly localized electromagnetic transients, such as gamma-ray bursts observed with the InterPlanetary Network. Both being potential hosts of astrophysical sources of gravitational waves, GLADE includes inactive and active galaxies as well. GLADE was constructed by cross-matching and combining data from five separate (but not independent) astronomical catalogues: GWGC, 2MPZ, 2MASS XSC, HyperLEDA, and SDSS-DR12Q. GLADE is complete up to
dL=37+3−4Mpc in terms of the cumulative B-band luminosity of galaxies within luminosity distance dL, and contains all of the brightest galaxies giving half of the total B-band luminosity up to dL=91Mpc. As B-band luminosity is expected to be a tracer of binary neutron star mergers (currently the prime targets of joint GW+EM detections), our completeness measures can be used as estimations of completeness for containing all binary neutron star merger hosts in the local Universe
Cold Strangelets Formation with Finite Size Effects in High Energy Heavy-Ion Collisions
We have studied the phase diagram and evolution of a strangelet in
equilibrium with a finite hadronic gas. Significant finite size modifications
of the phase diagram are found and their parameter dependences are studied.
With the inclusion of finite size effects we have also been able to obtain the
detailed properties of the cold strangelet emerging in the final stage of the
isentropic expansion of a finite strange fireball in high energy heavy-ion
collisions.Comment: 19 pages(RevTex), 11 Postscript figures; To appear in Phys. Rev.
The Dynamics of Poor Systems of Galaxies
We assemble and observe a sample of poor galaxy systems that is suitable for
testing N-body simulations of hierarchical clustering (Navarro, Frenk, & White
1997; NFW) and other dynamical halo models (e.g., Hernquist 1990). We (1)
determine the parameters of the density profile rho(r) and the velocity
dispersion profile sigma(R), (2) separate emission-line galaxies from
absorption-line galaxies, examining the model parameters and as a function of
spectroscopic type, and (3) for the best-behaved subsample, constrain the
velocity anisotropy parameter, beta, which determines the shapes of the galaxy
orbits.
The NFW universal profile and the Hernquist (1990) model both provide good
descriptions of the spatial data. In most cases an isothermal sphere is ruled
out. Systems with declining sigma(R) are well-matched by theoretical profiles
in which the star-forming galaxies have predominantly radial orbits (beta > 0);
many of these galaxies are probably falling in for the first time. There is
significant evidence for spatial segregation of the spectroscopic classes
regardless of sigma(R).Comment: 36 pages, 20 figures, and 5 tables. To appear in the Astrophysical
Journa
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