Uncovering Local Absorbed Active Galactic Nuclei with Swift and Suzaku
Uncovering low-level Fermi/GBM emission using orbital background subtraction
Underlying global features of the x-ray light curves of {\it swift} gamma-ray bursts
Understanding Compact Object Formation and Natal Kicks. III. The case of Cygnus X-1
Understanding Cygnus X-3 Through Multi-Wavelength Studies
Understanding Dual AGN Activation in the Nearby Universe
Understanding hadronic gamma-ray emission from supernova remnants
Understanding of GRB-SN Connection by General Relativistic MHD Simulations
Understanding Reverberation Lags in 1H0707-495
Understanding the New High Energy Data-sets Measured by BESS, CAPRICE and PAMELA on Antiproton Flux and $\bar{P}/P$ Ratios
Understanding the X-ray Flaring from Eta Car
Understanding ULX Nebulae in the Framework of Supercritical Accretion
Unidentifed gamma-ray sources: hunting gamma-ray blazars
Unidentified Gamma-Ray Sources as Ancient Pulsar Wind Nebulae
Unification of Pulses in Long and Short Gamma-Ray Bursts: Evidence from Pulse Properties and their Correlations
Unified interpretation of cosmic-ray nuclei and antiproton recent measurements
Unified Model of Radio and X-Ray Emission of Nova CI Cam 1998
Unifying the Zoo of Jet-Driven Stellar Explosions
Universal characteristics of ion-acoustic wave dynamics in magnetized plasmas with emphasis on Tsallis distribution
Universality of electron-positron distributions in extensive air showers