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

Book Review of \u3ci\u3e Plains Indian Rock Art\u3c/i\u3e by James D. Keyser and Michael A. Klassen

While its title purports the work to cover the North American Plains, it is, in fact, almost entirely restricted to the northwest Plains. There is a constant effort to attempt iconographic relationships with other areas, including the Columbia Plateau, the Eastern Woodlands, and Precambrian Shield, with inevitably debatable conclusions. Its basic contribution is its highly ambitious effort to synthesize and integrate the full body of northwestern Plains rock art both culturally and chronologically. Although the approach to cultural determinations in the archaeological past and their continuity into identifiable groups in historic times is probably more explicit and definitive than the data will bear, this is a commendable effort to make sense of the voluminous available data. The illustrations, impressive and perfectly done to clarify points in the text, reflect the main stylistic and typological modes of northwestern Plains rock art. The volume will very probably serve as a basic source for all further study of the subject

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