A Cosmic Ray Resolution to the Superbubble Energy-Crisis (2008)
Butt, Yousaf M., Bykov, Andrei M.
Superbubbles (SBs) are amongst the greatest injectors of energy into the Galaxy, and have been proposed to be the acceleration site of Galactic cosmic rays. They are thought to be powered by the fast...
The Molecular Environment of the Gamma-ray Source TeV J2032+4130 (2008)
Butt, Yousaf M., Schneider, Nicola, Dame, T. M., Brunt, Christopher
The mysterious very high energy gamma-ray source, TeV J2032+4130, is coincident with the powerful Cygnus OB2 stellar association, though a physical association between the two remains uncertain. It...
TeV gamma-rays from photo-disintegration/de-excitation of nuclei in Westerlund 2 (2007)
Anchordoqui, Luis A., Beacom, John F., Butt, Yousaf M., Goldberg, Haim, Palomares-Ruiz, Sergio, Weiler, Thomas J., ...
TeV gamma-rays can result from the photo-de-excitation of PeV cosmic ray nuclei after their parents have undergone photo-disintegration in an environment of ultraviolet photons. This process is...
Chandra Observations of the Gamma-ray Binary LSI+61303: Extended X-ray Structure? (2007)
Paredes, Josep M., Ribo, M., Bosch-Ramon, ValentÃ, West, Jennifer R., Butt, Yousaf M., Torres, Diego F., ...
We present a 50 ks observation of the gamma-ray binary LSI+61303 carried out with the ACIS-I array aboard the Chandra X-ray Observatory. This is the highest resolution X-ray observation of the source...
TeV J2032+4130: a not-so-dark Accelerator? (2006)
Butt, Yousaf M., Combi, Jorge A., Drake, Jeremy, Finley, John P., Konopelko, Alexander, Lister, Matthew, ...
The HEGRA gamma-ray source TeV J2032+4130 is considered the prototypical 'dark accelerator', since it was the first TeV source detected with no firm counterparts at lower frequencies. The Whipple...
ULXs, Microblazars, and the Unidentified EGRET sources (2003)
Butt, Yousaf M., Romero, Gustavo E., Torres, Diego F.
We suggest that ultraluminous X-ray sources (ULXs) and some of the variable low latitude EGRET gamma-ray sources may be two different manifestations of the same underlying phenomena: high-mass...
Did Egret Detect Distant Supernova Remnants? (2003)
Torres, Diego F., Romero, Gustavo E., Dame, Thomas M., Combi, Jorge A., Butt, Yousaf M.
It might be thought that supernova remnants (SNRs) more distant than a few kiloparsec from Earth could not have been detected by the EGRET experiment. This work analyzes the observational status of...
Supernova remnants and gamma-ray sources (2002)
Torres, Diego F., Romero, Gustavo E., Dame, Thomas M., Combi, Jorge A., Butt, Yousaf M.
A review of the possible relationship between gamma-ray sources and supernova remnants (SNRs) is presented. Particular emphasis is given to the analysis of the observational status of the problem of...
Jet-Induced Nucleosynthesis in Misaligned Microquasars (2002)
Butt, Yousaf M., Maccarone, Thomas J., Prantzos, Nikos
The jet axes and the orbital planes of microquasar systems are usually assumed to be approximately perpendicular, eventhough this is not currently an observational requirement. On the contrary, in...
Supernova-Remnant Origin of Cosmic Rays? (2002)
Butt, Yousaf M., Torres, Diego F., Romero, Gustavo E., Dame, Thomas M., Combi, Jorge A.
It is thought that Galactic cosmic ray (CR) nuclei are gradually accelerated to high energies (up to ~300 TeV/nucleon, where 1TeV=10^12eV) in the expanding shock-waves connected with the remnants of...
Molecular Beam Dumps as Tracers of Hadronic Cosmic Ray Sources: the Case of SNR IC443 (2002)
Butt, Yousaf M., Torres, Diego F., Combi, Jorge A., Dame, Thomas M., Romero, Gustavo E.
The gamma-ray & neutrino visibility of cosmic ray (CR) accelerators will be dramatically increased by the presence of molecular material abutting such sites due to the increased probability of pion...
Is the Supernova Remnant RX J1713.7-3946 a Hadronic Cosmic Ray Accelerator ? (2001)
Butt, Yousaf M., Torres, Diego F., Combi, Jorge A., Dame, Thomas, Romero, Gustavo E.
The non-thermal supernova remnant RX J1713.7-3946 (G347.3-0.5) has recently been shown to be a site of cosmic ray (CR) electron acceleration to TeV energies (Muraishi et al. 2000). Here we present...
Recently discovered pulsars and unidentified EGRET sources (2001)
Torres, Diego F., Butt, Yousaf M., Camilo, Fernando
We present a correlative study between all unidentified EGRET sources at low Galactic latitudes and the newly discovered pulsars in the released portion of the Parkes multibeam radio survey. We note...
The Chandra X-Ray Observatory's Radiation Environment and the AP-8/AE-8 Model (2000)
Virani, Shanil N., Mueller-Mellin, Reinhold, Plucinsky, Paul P., Butt, Yousaf M.
The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has...
Gaetz, T. J., Butt, Yousaf M., Edgar, Richard J., Eriksen, Kristoffer A., Plucinsky, Paul P., Schlegel, Eric M., ...
We present observations of the young, Oxygen-rich supernova remnant 1E0102.2-7219 taken by the Chandra X-ray Observatory during Chandra's Orbital Activation and Checkout phase. The boundary of the...