37219186
Constraints on the primordial curvature perturbation from primordial black holes
We calculate the constraints on the primordial curvature perturbation at the end of inflation from the present day abundance of primordial black holes (PBHs), as a function of the reheat temperature TRH. We first extend recent work on the formation of PBHs on scales which remain within the horizon during inflation and calculate the resulting constraints on the curvature perturbation. We then evaluate the constraint from PBHs that form, more conventionally, from super-horizon perturbations. The constraints apply for TRH<108 GeV and the inclusion of sub-horizon PBHs leads to a limit which is roughly three times tighter than the bound from super-horizon PBHs.
16034831
Probing the width of the MACHO mass function
The simplest interpretation of the microlensing events observed towards the Large Magellanic Cloud is that approximately half of the mass of the Milky Way halo is in the form of MAssive Compact Halo Objects with $M \sim 0.5 M_{\odot}$. This poses severe problems for stellar MACHO candidates, and leads to the consideration of more exotic objects such as primordial black holes (PBHs). Constraining the MACHO mass function will shed light on their nature. Using the current data we find, for four halo models, the best fit delta-function, power law and PBH mass functions. The best fit PBH mass functions, despite having significant finite width, have likelihoods which are similar to, and for one particular halo model greater than, those of the best fit delta functions. We also find that if the correct halo model is known then $\sim$ 500 events will be sufficient to determine whether the MACHO mass function has significant width, and will also allow determination of the mass function parameters to $\sim 5%$.
119021467
PRIMORDIAL BLACK HOLES AND EARLY COSMOLOGY
We describe the changes to the standard primordial black hole constraints on density perturbations if there are modifications to the standard cosmology between the time of formation and nucleosynthesis.
55672557
WIMP physics with ensembles of direct-detection experiments
if dierent classes of experiments see consistent signals and infer the same WIMP properties. In this work, we review the ideas, methods, and status of direct-detection searches. We focus in particular on extracting WIMP physics (WIMP interactions and phase-space distribution) from direct-detection data in the early discovery days when multiple experiments see of order dozens to hundreds of events. To demonstrate the essential complementarity of dierent direct-detection experiments in this context, we create mock data intended to represent the data from the near-future Generation 2 experiments. We consider both conventional supersymmetry-inspired benchmark points (with spin-independent and -dependent elastic cross sections just below current limits), as well as benchmark points for other classes of models (inelastic and eective-operator paradigms). We also investigate the eect on parameter estimation of loosening or dropping the assumptions about the local WIMP phase-space distribution. We arrive at two main conclusions. Firstly, teasing out WIMP physics with experiments depends critically on having a wide set of detector target materials, spanning a large range of target nuclear masses and spin-dependent sensitivity. It is also highly desirable to obtain data from low-threshold experiments. Secondly, a general reconstruction of the local WIMP velocity distribution, which will only be achieved if there are multiple experiments using dierent target materials, is critical to obtaining a robust and unbiased estimate of the WIMP mass.
117989592
Extracting Information about WIMP Properties from Direct Detection Experiments: Astrophysical Uncertainties
WIMP direct detection experiments probe the ultra-local dark matter density and velocity distribution. We review how uncertainties in these quantities affect the accuracy with which the WIMP mass and cross-section can be constrained or determined.
8787684
Determining the WIMP mass from a single direct detection experiment
The energy spectrum of nuclear recoils in Weakly Interacting Massive Particle (WIMP) direct detection experiments depends on the underlying WIMP mass (strongly for light WIMPs, weakly for heavy WIMPs). We discuss how the accuracy with which the WIMP mass could be determined by a single direct detection experiment depends on the detector configuration and the WIMP properties. In particular we examine the effects of varying the underlying WIMP mass, the detector target nucleus, exposure, energy threshold and maximum energy, the local velocity distribution and the background event rate and spectrum.
15965860
“Missing Link” Clouds in the Southern Galactic Plane Survey
We present an automated routine to search for H I self-absorption features within the Southern Galactic Plane Survey (SGPS). The data were taken with the Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope and encompass 3°×105° of sky in the Galactic plane. We apply our routine to this entire region and derive spin temperatures and column densities for 70 of the larger HISA complexes, finding spin temperatures ranging from 6 to 41 K with H I number densities of a few cm -3. These "missing link" clouds fill in the spin temperature and density gaps between dense molecular clouds and diffuse atomic clouds. We compare the H I emission with 12CO emission and find that ∼60% of detected H I self-absorption is correlated in space and in velocity with a molecular counterpart. This is potentially due to a molecular/atomic gas transition. We also compare H I self-absorption with Galactic spiral arms and discuss the possibility of using it as a spiral arm tracer. © 2005. The American Astronomical Society. All rights reserved.
18547017
The 'Rabbit': A Potential Radio Counterpart of GeV J1417-6100
We have mapped the radio emission in the error ellipse of GeV J1417-6100 (2EGS J1418-6049) at 13cm and 20cm using the Australia Telescope Compact Array. We find a large shell with extended wings , at the edge of which is a non-thermal, polarized structure with a center filled morphology (the ‘Rabbit’), coincident with an extended, hard X-ray source. We discuss the various sources seen within the ellipse as potential counterparts of the −ray source. We conclude that the most likely scenario is that the Rabbit is a wind nebula surrounding a radio-quiet −ray pulsar.
119307366
Multiwavelength diagnostic properties of Galactic planetary nebulae detected by the GLIMPSE-I
We uniformly analyse 136 optically detected planetary nebulae (PNe) and candidates from the GLIMPSE-I in order to develop robust, multiwavelength, classification criteria to augment existing diagnostics and provide pure PN samples. PNe represent powerful astrophysical probes. They are important dynamical tracers, key sources of interstellar medium chemical enrichment, windows into late stellar evolution and potent cosmological yardsticks. However, their utility depends on separating them unequivocally from the many nebular mimics which can strongly resemble bona fide PNe in traditional optical images and spectra. We merge new PNe from the carefully evaluated, homogeneous Macquarie-AAO-Strasbourg Hα PN Project (MASH-I) and MASH-II surveys, which offer a wider evolutionary range of PNe than hitherto available, with previously known PNe classified by SIMBAD. Mid-infrared (MIR) measurements vitally complement optical data because they reveal other physical processes and morphologies via fine-structure lines, molecular bands and dust. MIR colour–colour planes, optical emission-line ratios and radio fluxes show the unambiguous classification of PNe to be complex, requiring all available evidence. Statistical trends provide predictive value and we offer quantitative MIR criteria to determine whether an emission nebula is most likely to be a PN or one of the frequent contaminants such as compact H ii regions or symbiotic systems. Prerequisites have been optical images and spectra, but MIR morphology, colours, environment and a candidate’s MIR-to-radio flux ratio provide a more rigorous classification. Our ultimate goal is to recognize PNe using only MIR and radio characteristics, enabling us to trawl for PNe effectively even in heavily obscured regions of the Galaxy.
118443995
Opportunities for maser studies with the Square Kilometre Array
The Square Kilometre Array (SKA) is the radio telescope of the next generation, pro- viding an increase in sensitivity and angular resolution of two orders of magnitude over existing telescopes. Currently, the SKA is expected to span the frequency range 0.1 25 GHz with capa- bilities including a wide field-of-view and measurement of polarised emission. Such a telescope has enormous potential for testing fundamental physical laws and producing transformational discoveries. Important science goals include using H2O megamasers to make precise estimates of H0, which will anchor the extragalactic distance scale, and to probe the central structures of accretion disks around supermassive black holes in AGNs, to study OH megamasers associated with extreme starburst activity in distant galaxies and to study with unprecedented precision molecular gas and star formation in our Galaxy. 1. Overview The Square Kilometre Array (SKA) is a paradigm-shifting radio telescope for the next generation, providing an increase in sensitivity and angular resolution of two orders of magnitude over existing telescopes. It will be a truly global machine with an expected life- time of at least 50 years. Such a telescope has enormous potential for testing fundamental physical laws and producing transformational discoveries. The aim of the telescope is to answer some of the "big" questions in astronomy, such as what is the nature of dark energy, are we alone in the Universe, how did galaxies and black holes form, what is the origin and evolution of cosmic magnetism, can pulsars be used to detect gravity waves? The project is an international consortium of 50 institutions, spread over 17 coun- tries. Present governance is through the International SKA Steering Committee, with 21 members, which oversees the International SKA Project Officeand 6 targeted Working Groups. Engagement with inter-governmental agencies has begun to establish a gover- nance model and funding strategies. Currently, there are several pathfinder and demon- strator projects in progress for both science and technology developments.
16795941
Molecular LineObservations of the Tornado Nebula and its Eye
We present millimetre and NIR molecular-line observations of the Tornado nebula and its Eye. The observations were motivated by the presence of OH(1720 MHz) maser emission towards the nebula, believed to be an indicator of interaction between a supernova remnant and a molecular cloud. We found that the distribution of molecular gas around the Tornado complements its radio morphology, implying that the nebula’s appearance has been influenced by the structure of the surrou nding molecular gas. Our NIR H2 observations revealed the presence of shocked molecular gas at the location where the nebula is expanding into the surrounding molecular cloud. It has been suggested that the Eye of the Tornado is related to the nebula on the basis of their apparent proximity. Our NIR and millimetre-line observations show that the two objects are not spatially related. Br line emission, in conjuction with IR data at longer wavelengths and high-resolution radio continuum observations, suggests that the Eye is a massive protostellar sou rce deeply embedded within a dense molecular core.