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Fully 3D cosmological simulations of scalar field dark matter with self-interactions, also known as Bose-Einstein condensate dark matter, are performed using a set of effective hydrodynamic equations. These are derived from the non-linear Schr\"odinger equation by performing a smoothing operation over scales larger than the de Broglie wavelength, but smaller than the self-interaction Jeans' length. The dynamics on the de Broglie scale become an effective thermal energy in the hydrodynamic approximation, which is assumed to be subdominant in the initial conditions, but become important as structures collapse and the fluid is shock-heated. The halos that form have Navarro-Frenk-White envelopes, while the centers become cored due to the fluid pressures (thermal + self-interaction). The core radii are mostly determined by the self-interaction Jeans' length, even though the effective thermal energy eventually dominates over the self-interaction energy everywhere, a result that is insensitive to the initial smallness of the thermal energy. Scaling relations for the simulated population of halos are compared with Milky Way dwarf spheroidals and nearby galaxies, assuming a Burkert halo profile, and are found to not match, also for core radii $R_c\approx 1\text{kpc}$, which has generally been the value expected to resolve the cusp-core issue. However, the simulations have a limited volume, and therefore a limited halo mass range, include no baryonic physics, and use fiducial cold dark matter initial conditions with a cut-off near the Jeans' length at $z=50$, all of which can affect the halo properties. [Abridged], Comment: 15 pages, 11 figures, 4 tables

Constraints on the cosmic history of self-interacting Bose-Einstein condensed (SIBEC) dark matter (DM) are obtained using the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO), growth factor measurements, and type Ia supernovae (SNIa) distances. Four scenarios are considered, one with purely SIBEC-DM, and three in which SIBEC-DM is the final product of some transition from different initial states, which are either cold, warm, or has a constant equation of state. Using a fluid approximation for the self-interacting scalar field it is found that in the simplest scenario of purely SIBEC-DM the self-interaction necessary for solving the cusp-core problem, with core-radii of low-mass halos of order $R_c\gtrsim 1\text{kpc}$, is excluded at $2.4\sigma$, or $98.5\%$ confidence. Introducing a transition, however, relaxes this constraint, but the transitions are preferred to be after matter-radiation equality, and the initial phase to be cold., Comment: 25 pages, 10 figures, 2 tables. Minor changes from previous version

The aim of the present work is to better understand the gravitational drag forces, i.e. dynamical friction, acting on massive objects moving through a self-interacting Bose-Einstein condensate, also known as a superfluid, at finite temperatures. This is relevant for light scalar models of dark matter with weak self-interactions that require nonzero temperatures, or that have been heated inside galaxies. We derived expressions for dynamical friction using linear perturbation theory, and compared these to numerical simulations in which nonlinear effects are included. After testing the linear result, it was applied to the Fornax dwarf spheroidal galaxy, and two of its gravitationally bound globular clusters. Dwarf spheroidals are well-suited for indirectly probing properties of dark matter, and so by estimating the rate at which these globular clusters are expected to sink into their host halo due to dynamical friction, we inferred limits on the superfluid dark matter parameter space. The dynamical friction in a finite-temperature superfluid is found to behave very similarly to the zero-temperature limit, even when the thermal contributions are large. However, when a critical velocity for the superfluid flow is included, the friction force can transition from the zero-temperature value to the value in a conventional fluid. Increasing the mass of the perturbing object induces a similar transition to when lowering the critical velocity. When applied to two of Fornax's globular clusters, we find that the parameter space preferred in the literature for a zero-temperature superfluid yields decay times that are in agreement with observations. However, the present work suggests that increasing the temperature, which is expected to change the preferred parameter space, may lead to very small decay times, and therefore pose a problem for finite-temperature superfluid models of dark matter., Comment: 16 pages, 8 figures, 3 tables. Accepted for publication in A&A

We intend to understand cosmological structure formation within the framework of superfluid models of dark matter with finite temperatures. Of particular interest is the evolution of small-scale structures where the pressure and superfluid properties of the dark matter fluid are prominent. We compare the growth of structures in these models with the standard cold dark matter paradigm and non-superfluid dark matter. The equations for superfluid hydrodynamics were computed numerically in an expanding $\Lambda$CDM background with spherical symmetry; the effect of various superfluid fractions, temperatures, interactions, and masses on the collapse of structures was taken into consideration. We derived the linear perturbation of the superfluid equations, giving further insights into the dynamics of the superfluid collapse. We found that while a conventional dark matter fluid with self-interactions and finite temperatures experiences a suppression in the growth of structures on smaller scales, as expected due to the presence of pressure terms, a superfluid can collapse much more efficiently than was naively expected due to its ability to suppress the growth of entropy perturbations and thus gradients in the thermal pressure. We also found that the cores of the dark matter halos initially become more superfluid during the collapse, but eventually reach a point where the superfluid fraction falls sharply. The formation of superfluid dark matter halos surrounded by a normal fluid dark matter background is therefore disfavored by the present work., Comment: 10 pages, 9 figures. Accepted by A&A

HgCdTe detector arrays with a cutoff wavelength of ~10 ${\mu}$m intended for the NEOCam space mission were subjected to proton beam irradiation at the University of California Davis Crocker Nuclear Laboratory. Three arrays were tested - one with 800 $\mu$m substrate intact, one with 30 $\mu$m substrate, and one completely substrate-removed. The CdZnTe substrate, on which the HgCdTe detector is grown, has been shown to produce luminescence in shorter wave HgCdTe arrays that causes elevated signal in non-hit pixels when subjected to proton irradiation. This testing was conducted to ascertain whether or not full substrate removal is necessary. At the dark level of the dewar, we detect no luminescence in non-hit pixels during proton testing for both the substrate-removed detector array and the array with 30 ${\mu}$m substrate. The detector array with full 800 ${\mu}$m substrate exhibited substantial photocurrent for a flux of 103 protons/cm$^2$-s at a beam energy of 18.1 MeV (~ 750 e$^-$/s) and 34.4 MeV ($\sim$ 65 e$^-$/s). For the integrated space-like ambient proton flux level measured by the Spitzer Space Telescope, the luminescence would be well below the NEOCam dark current requirement of <200 e$^-$/s, but the pattern of luminescence could be problematic, possibly complicating calibration., Comment: 9 figures, 32 pages

The Egg Nebula has been regarded as the archetype of bipolar proto-planetary nebulae, yet we lack a coherent model that can explain the morphology and kinematics of the nebular and dusty components observed at high-spatial and spectral resolution. Here, we report on two sets of observations obtained with the Keck Adaptive Optics Laser Guide Star: H to M-band NIRC2 imaging, and narrow bandpath K-band OSIRIS 3-D imaging-spectroscopy (through the H2 2.121micron emission line). While the central star or engine remains un-detected at all bands, we clearly resolve the dusty components in the central region and confirm that peak A is not a companion star. The spatially-resolved spectral analysis provide kinematic information of the H_2 emission regions in the eastern and central parts of the nebula and show projected velocities for the H_2 emission higher than 100 km/s. We discuss these observations against a possible formation scenario for the nebular components., Comment: 5 pages, 2 figures, to appear in the proceedings of the conference "Asymetrical Planetary Nebula IV", edited by Romano L.M. Corradi, Arturo Manchado and Noam Soker

We have searched the four brightest objects in the Kuiper belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known), 2003 EL61, and 2003 UB313. The object 2005 FY9, the brightest Kuiper belt object after Pluto, does not have a satellite detectable within 0.4 arcseconds with a brightness of more than 0.5% of the primary. The presence of satellites to 3 of the 4 brightest Kuiper belt objects is inconsistent with the fraction of satellites in the Kuiper belt at large at the 99.1% confidence level, suggesting a different formation mechanism for these largest KBO satellites. The satellites of 2003 EL61 and 2003 UB313, with fractional brightnesses of 5% and 2% of their primaries, respectively, are significantly fainter relative to their primaries than other known Kuiper belt object satellites, again pointing to possible differences in their origin.

(Abridged) We present the first Laser Guide Star Adaptive Optics (LGS-AO) observations of the Galactic center. LGS-AO has dramatically improved the quality, robustness, and versatility with which high angular resolution infrared images of the Galactic center can be obtained with the W. M. Keck II 10-meter telescope. Specifically, Strehl ratios of 0.7 and 0.3 at L'[3.8 micron] and K'[2.1 micron], respectively, are achieved in these LGS-AO images. During our observations, the infrared counterpart to the central supermassive black hole, Sgr A*-IR, showed significant infrared intensity variations, with observed L' magnitudes ranging from 12.6 to 14.5 mag. The faintest end of our L' detections, 1.3 mJy (dereddened), is the lowest level of emission yet observed for this source by a factor of 3. No significant variation in the location of SgrA*-IR is detected as a function of either wavelength or intensity. Near a peak in its intensity, we obtained the first measurement of SgrA*-IR's K'-L' color (3.0 +- 0.2 mag, observed), which corresponds to an intrinsic spectral index of -0.5 +- 0.3. This is significantly bluer than other recent infrared measurements. Because our measurement was taken at a time when Sgr A* was ~6 times brighter in the infrared than the other measurements, we posit that the spectral index of the emission arising from the vicinity of our Galaxy's central black hole may depend on the strength of the flare, with stronger flares giving rise to a higher fraction of high energy electrons in the emitting region., Comment: Accepted for publication in ApJ (to appear in 20 Dec 2005, vol. 635 issue), 9 pages and 5 figures

The Center for Adaptive Optics Treasury Survey (CATS) aims to combine deep HST images in the optical with deep Keck adaptive optics (AO) data in the near-infrared (NIR) to study distant galaxies, AGN, and supernovae. We recently achieved an important new milestone by securing the first Keck laser guide star AO image of faint galaxies. Six galaxies with redshifts ranging from 0.3-1.0 were targeted in one pointing in the GOODS-S field. Two are Chandra Deep Field South sources, XID-56 and XID-536, with complex morphologies suggestive of recent merger activity. Substructures seen in the NIR AO image (FWHM ~ 0.1"), including multiple tight knots in XID-56 and a double nucleus in XID-536, are confirmed in the optical HST images. These structures are unresolved in the best seeing-limited (FWHM ~ 0.5") NIR images. Stellar population synthesis models of the substructures indicate that XID-56 is a gas rich merger with a recent burst of star formation and significant amounts of dust. XID-536 appears to be a merger of two evolved stellar populations., Comment: 6 pages, 4 figures, 1 table, accepted ApJL 2005