Astrophysics 32 7 Lecture 7 : Cosmic Distances
نویسنده
چکیده
GR states that the laws of physics are the same in any coordinates. However, some coordinates are easier to work with then others. One such set of coordinates are comoving coordinates in which an observer is comoving with the Hubble flow. Only for these observers in the comoving coordinates, the Universe is isotropic (otherwise, portions of the Universe will exhibit a systematic bias: portions of the sky will appear systematically blueor red-shifted).
منابع مشابه
Lecture Notes on High Energy Cosmic Rays
I give a concise introduction into high energy cosmic ray physics, including also few related aspects of high energy gamma-ray and neutrino astrophysics. The main emphasis is placed on astrophysical questions, and the level of the presentation is kept basic.
متن کاملTopological Defect Models of Structure Formation after the Cobe Discovery of Cmb Anisotropies
The COBE satellite has discovered anisotropies in the cosmic microwave background (CMB) consistent with a scale invariant spectrum of density perturbations1). As reviewed in this lecture, topological defect models of structure formation generically produce such a spectrum. We give a summary of the cosmic string and global texture models, focusing on distinct observational signatures in large-sc...
متن کاملTime Delays in Cosmic Ray Propagation
Cosmic Rays (CR) travel at speeds essentially indistinguishable from the speed of light. However whilst travelling through magnetic fields, both regular and turbulent, they are delayed behind the light since they are usually charged particles and their paths are not linear. Those delays can be so long that they are an impediment to correctly identifying sources which may be variable in time. Fu...
متن کاملNaked Singularities , Cosmic Time Machines and Impulsive Events
Continued gravitational collapse gives rise to curvature singularities. If a curvature singularity is globally naked then the space-time may be causally future ill-behaved admitting closed time-like or null curves which extend to asymptotic distances and generate a Cosmic Time Machine (de Felice (1995) Lecture Notes in Physics 455, 99). The conjecture that Cosmic Time Machines give rise to high...
متن کاملNeutrino probe of cosmic ray astrophysics and new physics at sub-fermi distances
We show that if the evolution of cosmic ray sources follows that of active galactic nuclei, the upper limit on the diffuse flux of tau neutrinos from the Pierre Auger Observatory marginally constrains the proton fraction at the end of the energy spectrum. We also discuss prospects to uncover new physics leptophobic interactions using future Auger data.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2009