47 research outputs found
Are High-Redshift Quasars Blurry?
It has been suggested that the fuzzy nature of spacetime at the Planck scale
may cause lightwaves to lose phase coherence, and if severe enough this could
blur images of distant point-like sources sufficiently that they do not form an
Airy pattern at the focal plane of a telescope. Blurring this dramatic has
already been observationally ruled out by images from Hubble Space Telescope
(HST), but I show that the underlying phenomenon could still be stronger than
previously considered. It is harder to detect, which may explain why it has
gone unseen. A systematic search is made in archival HST images of among the
highest known redshift quasars. Planck-scale induced blurring may be evident,
but this could be confused with partially resolved sources.Comment: 8 pages, 5 figures, accepted for publication in the Ap
A Star-Forming Shock Front in Radio Galaxy 4C+41.17 Resolved with Laser-Assisted Adaptive Optics Spectroscopy
Near-infrared integral-field spectroscopy of redshifted [O III], H-beta and
optical continuum emission from z=3.8 radio galaxy 4C+41.17 is presented,
obtained with the laser-guide-star adaptive optics facility on the Gemini North
telescope. Employing a specialized dithering technique, a spatial resolution of
0.10 arcsec or 0.7 kpc is achieved in each spectral element, with velocity
resolution of ~70 km/s. Spectra similar to local starbursts are found for
bright knots coincident in archival Hubble Space Telescope (HST)
restframe-ultraviolet images, which also allows a key line diagnostic to be
mapped together with new kinematic information. There emerges a clearer picture
of the nebular emission associated with the jet in 8.3 GHz and 15 GHz Very
Large Array maps, closely tied to a Ly-alpha-bright shell-shaped structure seen
with HST. This supports a previous interpretation of that arc tracing a bow
shock, inducing 10^10-11 M_solar star-formation regions that comprise the
clumpy broadband optical/ultraviolet morphology near the core.Comment: 10 pages, 6 figures, accepted for publication in A
Holographic Quantum-Foam Blurring, and Localization of Gamma-Ray Burst GRB221009A
Gamma-ray burst GRB221009A was of unprecedented brightness in gamma-rays and
X-rays, and through to the far ultraviolet, allowing for identification within
a host galaxy at redshift z=0.151 by multiple space and ground-based
optical/near-infrared telescopes and enabling a first association - via
cosmic-ray air-shower events - with a photon of 251 TeV. That is in direct
tension with a potentially observable phenomenon of quantum gravity (QG), where
spacetime "foaminess" accumulates in wavefronts propagating cosmological
distances, and at high-enough energy could render distant yet bright pointlike
objects invisible, by effectively spreading their photons out over the whole
sky. But this effect would not result in photon loss, so it remains distinct
from any absorption by extragalactic background light. A simple multiwavelength
average of foam-induced blurring is described, analogous to atmospheric seeing
from the ground. When scaled within the fields of view for the Fermi and Swift
instruments, it fits all z<5 GRB angular-resolution data of 10 MeV or any
lesser peak energy and can still be consistent with the highest-energy
localization of GRB221009A: a limiting bound of about 1 degree is in agreement
with a holographic QG-favored formulation.Comment: 11 pages, 3 figures, accepted for publication in Galaxie
Radio Galaxy 3C 230 Observed with Gemini Laser-Adaptive-Optics Integral-Field Spectroscopy
The Altair laser-guide-star adaptive optics facility combined with the
Near-Infrared Integral Field Spectrometer (NIFS) on Gemini North have been
employed to study the morphology and kinematics of 3C 230 at z=1.5, the first
such observations of a high-redshift radio galaxy. These suggest a bi-polar
outflow spanning 0"9 (~16 kpc projected distance for a standard lambda-CDM
cosmology) reaching a mean relative velocity of 235 km/s in redshifted H-alpha
+ [NII] and [SII] emission. Structure is resolved to 0"1 (0.8 kpc), well
correlated with optical images from the Hubble Space Telescope and Very Large
Array radio maps obtained at similar spatial resolution. Line diagnostics
suggest that over the 10^7 yr to 10^8 yr duration of its AGN activity, gas has
been ejected into bright turbulent lobes at rates comparable to star formation,
although constituting perhaps only 1 percent of the baryonic mass in the
galaxy.Comment: 14 pages, 5 figures, accepted for publication in Astronomical Journa
Preliminary DIMM and MASS Nighttime Seeing Measurements at PEARL, in the Canadian High Arctic
Results of deploying a Differential Image Motion Monitor (DIMM) and a DIMM
combined with a Multi-Aperture Scintillation Sensor (MASS/DIMM) are reported
for campaigns in 2011 and 2012 on the roof of the Polar Environment Atmospheric
Research Laboratory (PEARL). This facility is on a 610-m-high ridge at latitude
80 degrees N, near the Eureka weatherstation on Ellesmere Island, Canada. The
median seeing at 8-m elevation is 0.85 arcsec or better based on DIMM data
alone, but is dependent on wind direction, and likely includes a component due
to the PEARL building itself. Results with MASS/DIMM yield a median seeing less
than 0.76 arcsec. A semi-empirical model of seeing versus ground wind speed is
introduced which allows agreement between these datasets, and with previous
boundary-layer profiling by lunar scintillometry from the same location. This
further suggests that best 20 percentile seeing reaches 0.53 arcsec, of which
typically 0.30 arcsec is due to the free atmosphere. Some discussion for
guiding future seeing instrumentation and characterization at this site is
provided.Comment: 16 pages, 11 figures, accepted for PAS
Mauna Kea Sky Transparency from CFHT SkyProbe Data
Nighttime sky transparency statistics on Mauna Kea are reported based on data
from the Canada-France-Hawaii Telescope SkyProbe monitor. We focus on the
period beginning with the start of MegaCam wide-field optical imager operations
in 2003, and continuing for almost three years. Skies were clear enough to
observe on 76% of those nights; attenuations were less than 0.2 magnitudes up
to 60% of the time. An empirical model of cloud attenuation and duration is
presented allowing us to further characterize the photometric conditions. This
is a good fit tothe SkyProbe data, and indicates that Mauna Kea skies are truly
photometric (without cloud) an average of 56% of the time, with moderate
seasonal variation. Continuous monitoring of transparency during the night is
necessary to overcome fluctuations in attenuation due to thin cloud.Comment: 10 pages, 6 figures, submitted to PAS
New Exoplanet Surveys in the Canadian High Arctic at 80 Degrees North
Observations from near the Eureka station on Ellesmere Island, in the
Canadian High Arctic at 80 degrees North, benefit from 24-hour darkness
combined with dark skies and long cloud-free periods during the winter. Our
first astronomical surveys conducted at the site are aimed at transiting
exoplanets; compared to mid-latitude sites, the continuous darkness during the
Arctic winter greatly improves the survey's detection efficiency for
longer-period transiting planets. We detail the design, construction, and
testing of the first two instruments: a robotic telescope, and a set of very
wide-field imaging cameras. The 0.5m Dunlap Institute Arctic Telescope has a
0.8-square-degree field of view and is designed to search for potentially
habitable exoplanets around low-mass stars. The very wide field cameras have
several-hundred-square-degree fields of view pointed at Polaris, are designed
to search for transiting planets around bright stars, and were tested at the
site in February 2012. Finally, we present a conceptual design for the Compound
Arctic Telescope Survey (CATS), a multiplexed transient and transit search
system which can produce a 10,000-square-degree snapshot image every few
minutes throughout the Arctic winter.Comment: 11 pages, 6 figures, SPIE vol 8444, 201