17391793
The Hubble Space Telescope key project on the extragalactic distance scale XXIV: the calibration of Tully-Fisher relations and the value of the Hubble constant
This paper presents the calibration of BVRIH-0.5 Tully-Fisher relations based on Cepheid distances to 21 galaxies within 25 Mpc and 23 clusters within 10,000 km s-1. These relations have been applied to several distant cluster surveys in order to derive a value for the Hubble constant, H0, mainly concentrating on an I-band all-sky survey by Giovanelli and collaborators, consisting of total I magnitudes and 50% line width data for ~550 galaxies in 16 clusters. For comparison, we also derive the values of H0 using surveys in the B and V bands by Bothun and collaborators, and in H band by Aaronson and collaborators. Careful comparisons with various other databases from the literature suggest that the H-band data, which have isophotal magnitudes extrapolated from aperture magnitudes rather than total magnitudes, are subject to systematic uncertainties. Taking a weighted average of the estimates of Hubble constants from four surveys, we obtain H0 = 71 ± 4 (random) ± 7 (systematic). We have also investigated how the value of H0 is affected by various systematic uncertainties, such as the internal extinction correction method used, Tully-Fisher slopes and shapes, a possible metallicity dependence of the Cepheid period-luminosity relation, and cluster population incompleteness bias.
120455459
Long-period variables in the Large Magellanic Cloud. II. Infrared photometry, spectral classification, AGB evolution, and spatial distribution
Infrared JHK photometry and visual spectra have been obtained for a large sample of long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Various aspects of the asymptotic giant branch (AGB) evolution of LPVs are discussed using these data. The birth/death rate of LPVs of different ages in the LMC is compared with the birth rates of appropriate samples of planetary nebulas, clump stars, Cepheids, and OH/IR stars. It appears that there are much fewer large-amplitude LPVs per unit galactic stellar mass in the LMC than in the Galaxy. It is suggested that this may be due to the fact that the evolved intermediate-age AGB stars in the LMC often turn into carbon stars, which tend to have smaller pulsation amplitudes than M stars. There is also a major discrepancy between the number of LPVs in the LMC (and in the Galaxy) and the number predicted by the theories of AGB evolution, pulsation, and mass loss. A distance modulus to the LMC of 18.66 + or - 0.05 is derived by comparing the LMC LPVs with P about 200 days with the 47 Tucanae Mira variables in the (K, log P) plane. 64 refs.
123113862
The Hubble Space Telescope Extragalactic Distance Scale Key Project. 1: The discovery of Cepheids and a new distance to M81
197531313
The HST Key Project on the Extragalactic Distance Scale. XXVIII. Combining the Constraints on the Hubble Constant
Since the launch of the Hubble Space Telescope nine years ago, Cepheid distances to 25 galaxies have been determined for the purpose of calibrating secondary distance indicators. A variety of these can now be calibrated, and the accompanying papers by Sakai, Kelson, Ferrarese, and Gibson employ the full set of 25 galaxies to consider the Tully-Fisher relation, the fundamental plane of elliptical galaxies, Type Ia supernovae, and surface brightness fluctuations. 
When calibrated with Cepheid distances, each of these methods yields a measurement of the Hubble constant and a corresponding measurement uncertainty. We combine these measurements in this paper, together with a model of the velocity field, to yield the best available estimate of the value of H_0 within the range of these secondary distance indicators and its uncertainty. 
The result is H_0 = 71 +/- 6 km/sec/Mpc. The largest contributor to the uncertainty of this 67% confidence level result is the distance of the Large Magellanic Cloud, which has been assumed to be 50 +/- 3 kpc.
204935980
The HST Key Project on the Extragalactic Distance Scale XII. The Discovery of Cepheids and a New Distance to NGC 2541
We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST). A total of 25 exposures (divided into 13 epochs) are obtained using the F555W filter (transformed to Johnson V), and nine exposures (divided into five epochs) using the F814W filter (transformed to Cousins I). Photometric reduction of the data is performed using two independent packages, DoPHOT and DAOPHOT II/ALLFRAME, which give very good agreement in the measured magnitudes. A total of 34 bona fide Cepheids, with periods ranging from 12 to over 60 days, are identified based on both sets of photometry. By fitting V and I period-luminosity relations, apparent distance moduli are derived assuming a Large Magellanic Cloud distance modulus and mean color excess of 18.50 +/- 0.10 mag and E(B-V) = 0.10 mag respectively. Adopting A(V)/E(V-I)=2.45, we obtain a true distance modulus to NGC 2541 of 30.47 +/- 0.11 (random) +/- 0.12 (systematic) mag (D = 12.4 +/- 0.6 (random) +/- 0.7 (systematic) Mpc), and a total (Galactic plus internal) mean color excess E(B-V) = 0.08 +/- 0.05 (internal error) mag.
118970559
A Database of Cepheid Distance Moduli and TRGB, GCLF, PNLF and SBF Data Useful for Distance Determinations
We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The database includes all data published as of July 15, 1999. The main strength of this compilation resides in all data being on a consistent and homogeneous system: all Cepheid distances are derived using the same calibration of the period-luminosity relation, the treatment of errors is consistent for all indicators, measurements which are not considered reliable are excluded. As such, the database is ideal for inter-comparing any of the distance indicators considered, or for deriving a Cepheid calibration to any secondary distance indicator. Specifically, the database includes: 1) Cepheid distances, extinctions and metallicities; 2) apparent magnitudes of the PNLF cutoff; 3) apparent magnitudes and colors of the turnover of the GCLF (both in the V- and B-bands); 4) apparent magnitudes of the TRGB (in the I-band) and V-I colors at and 0.5 magnitudes fainter than the TRGB; 5) apparent surface brightness fluctuation magnitudes I, K', K_short, and using the F814W filter with the HST/WFPC2. In addition, for every galaxy in the database we give reddening estimates from DIRBE/IRAS as well as HI maps, J2000 coordinates, Hubble and T-type morphological classification, apparent total magnitude in B, and systemic velocity. (Abridged)
55018033
Modeling multipolar gravitational-wave emission from small mass-ratio mergers
Using the effective-one-body (EOB) formalism and a time-domain Teukolsky code, we generate inspiral, merger, and ringdown waveforms in the small-mass-ratio limit. We use EOB inspiral and plunge trajectories to build the Teukolsky-equation source term, and compute full coalescence waveforms for a range of black-hole spins. By comparing EOB waveforms that were recently developed for comparablemass binary black holes to these Teukolsky waveforms, we improve the EOB model for the (2, 2), (2, 1), (3, 3), and (4, 4) modes. Our results can be used to quickly and accurately extract useful information about merger waves for binaries with spin and should be useful for improving analytic models of such binaries.
121643265
The Science benefits and Preliminary Design of the Southern hemisphere Gravitational Wave Detector AIGO.
The proposed southern hemisphere gravitational wave detector AIGO increases the projected average baseline of the global array of ground based gravitational wave detectors by a factor ~4. This allows the world array to be substantially improved. The orientation of AIGO allows much better resolution of both wave polarisations. This enables better distance estimates for inspiral events, allowing unambiguous optical identification of host galaxies for about 25% of neutron star binary inspiral events. This can allow Hubble Law estimation without optical identification of an outburst, and can also allow deep exposure imaging with electromagnetic telescopes to search for weak afterglows. This allows independent estimates of cosmological acceleration and dark energy as well as improved understanding of the physics of neutron star and black hole coalescences. This paper reviews and summarises the science benefits of AIGO and presents a preliminary conceptual design.
10008243
Short GRB and binary black hole standard sirens as a probe of dark energy
Observations of the gravitational radiation from well-localized, inspiraling compact-object binaries can measure absolute source distances with high accuracy. When coupled with an independent determination of redshift through an electromagnetic counterpart, these standard sirens can provide an excellent probe of the expansion history of the Universe and the dark energy. Short $\ensuremath{\gamma}$-ray bursts, if produced by merging neutron star binaries, would be standard sirens with known redshifts detectable by ground-based gravitational wave (GW) networks such as Advanced Laser Interferometer Gravitational-wave Observatory (LIGO), Virgo, and Australian International Gravitational Observatory (AIGO). Depending upon the collimation of these GRBs, the measurement of about 10 GW-GRB events (corresponding to about 1 yr of observation with an advanced GW detector network and an all-sky GRB monitor) can measure the Hubble constant $h$ to $\ensuremath{\sim}2--3%$. When combined with measurement of the absolute distance to the last scattering surface of the cosmic microwave background, this determines the dark energy equation of state parameter $w$ to $\ensuremath{\sim}9%$. Similarly, supermassive binary black hole inspirals will be standard sirens detectable by Laser Interferometer Space Antenna (LISA). Depending upon the precise redshift distribution, $\ensuremath{\sim}100$ sources could measure $w$ at the $\ensuremath{\sim}4%$ level.
18693900
TeV Gamma-Ray Observations of the Perseus and Abell 2029 Galaxy Clusters
Galaxy clusters might be sources of TeV gamma rays emitted by high-energy protons and electrons accelerated by large-scale structure formation shocks, galactic winds, or active galactic nuclei. Furthermore, gamma rays may be produced in dark matter particle annihilation processes at the cluster cores. We report on observations of the galaxy clusters Perseus and A2029 using the 10 m Whipple Cerenkov telescope during the 2003-2004 and 2004-2005 observing seasons. We apply a two-dimensional analysis technique to scrutinize the clusters for TeV emission. In this paper we first determine flux upper limits on TeV gamma-ray emission from point sources within the clusters. Second, we derive upper limits on the extended cluster emission. We subsequently compare the flux upper limits with EGRET upper limits at 100 MeV and theoretical models. Assuming that the gamma-ray surface brightness profile mimics that of the thermal X-ray emission and that the spectrum of cluster cosmic rays extends all the way from thermal energies to multi-TeV energies with a differential spectral index of -2.1, our results imply that the cosmic-ray proton energy density is less than 7.9% of the thermal energy density for the Perseus Cluster.
118706760
Stellar Collapse and Gravitational Waves
The new generation of gravitational wave (GW) detectors have the potential to open a new window onto the violent dynamics of core collapse. Although it is certain that core collapse events generate gravitational radiation, understanding the characteristics of the radiation—whether it can be measured with the new detectors, and the best way to go about doing so—is a challenging problem. In this chapter we review the promise of GWs as observational probes, including a discussion of the current state of new detectors, and discuss the status of work to understand the waves generated by stellar core collapse.