3,872 research outputs found
Distance Measurement of Galaxies to Redshift of 0.1 using the CO-Line Tully-Fisher Relation
We report on the first results of a long-term project to derive distances of
galaxies at cosmological distances by applying the CO-line width-luminosity
relation. We have obtained deep CO-line observations of galaxies at redshifts
up to 29,000 km/s using the Nobeyama 45-m mm-wave Telescope, and some
supplementary data were obtained by using the IRAM 30-m telescope. We have
detected the CO line emission for several galaxies, and used their CO line
widths to estimate the absolute luminosities using the line-width-luminosity
relation. In order to obtain photometric data and inclination correction, we
also performed optical imaging observations of the CO-detected galaxies using
the CFHT 3.6-m telescope at high resolution. The radio and optical data have
been combined to derive the distance moduli and distances of the galaxies, and
Hubble ratios were estimated for these galaxies. We propose that the CO line
width-luminosity relation can be a powerful method to derive distances of
galaxies to redfhift of z = 0.1 and to derive the Hubble ratio in a significant
volume of the universe.
Key words: Cosmology - Galaxies: general - Distance scale - CO lineComment: To appear in PASJ, Plain Tex, 3 figures (in 10 ps files
Evaluating the effectiveness of physical shape-change for in-pocket mobile device notifications
Audio and vibrotactile output are the standard mechanisms mobile devices use to attract their owner's attention. Yet in busy and noisy environments, or when the user is physically active, these channels sometimes fail. Recent work has explored the use of physical shape-change as an additional method for conveying notifications when the device is in-hand or viewable. However, we do not yet understand the effectiveness of physical shape-change as a method for communicating in-pocket notifications. This paper presents three robustly implemented, mobile-device sized shape-changing devices, and two user studies to evaluate their effectiveness at conveying notifications. The studies reveal that (1) different types and configurations of shape-change convey different levels of urgency and; (2) fast pulsing shape-changing notifications are missed less often and recognised more quickly than the standard slower vibration pulse rates of a mobile device
Solving the cosmic lithium problems with primordial late-decaying particles
We investigate the modifications to predictions for the abundances of light
elements from standard Big-Bang nucleosynthesis when exotic late-decaying
particles with lifetimes exceeding ~1 sec are prominent in the early Universe.
Utilising a model-independent analysis of the properties of these long-lived
particles, we identify the parameter space associated with models that are
consistent with all observational data and hence resolve the much discussed
discrepancies between observations and theoretical predictions for the
abundances of Li^7 and Li^6.Comment: 6 pages, 3 figures, submitted to Physical Review D; minor changes to
reference
Neutrino mass from cosmology: Impact of high-accuracy measurement of the Hubble constant
Non-zero neutrino mass would affect the evolution of the Universe in
observable ways, and a strong constraint on the mass can be achieved using
combinations of cosmological data sets. We focus on the power spectrum of
cosmic microwave background (CMB) anisotropies, the Hubble constant H_0, and
the length scale for baryon acoustic oscillations (BAO) to investigate the
constraint on the neutrino mass, m_nu. We analyze data from multiple existing
CMB studies (WMAP5, ACBAR, CBI, BOOMERANG, and QUAD), recent measurement of H_0
(SHOES), with about two times lower uncertainty (5%) than previous estimates,
and recent treatments of BAO from the Sloan Digital Sky Survey (SDSS). We
obtained an upper limit of m_nu < 0.2eV (95% C.L.), for a flat LambdaCDM model.
This is a 40% reduction in the limit derived from previous H_0 estimates and
one-third lower than can be achieved with extant CMB and BAO data. We also
analyze the impact of smaller uncertainty on measurements of H_0 as may be
anticipated in the near term, in combination with CMB data from the Planck
mission, and BAO data from the SDSS/BOSS program. We demonstrate the
possibility of a 5 sigma detection for a fiducial neutrino mass of 0.1eV or a
95% upper limit of 0.04eV for a fiducial of m_nu = 0eV. These constraints are
about 50% better than those achieved without external constraint. We further
investigate the impact on modeling where the dark-energy equation of state is
constant but not necessarily -1, or where a non-flat universe is allowed. In
these cases, the next-generation accuracies of Planck, BOSS, and 1% measurement
of H_0 would all be required to obtain the limit m_nu < 0.05 - 0.06eV (95%
C.L.) for the fiducial of m_nu = 0eV. The independence of systematics argues
for pursuit of both BAO and H_0 measurements.Comment: 22 pages, 6 figures, 12 table
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