In today’s paper, the authors study how the periods of two black hole x-ray binaries are changing. They find that the periods are decaying faster than expected based on standard theoretical arguments.
Field lines are a powerful tool for building intuition for a complex geometric object.
The densest galaxy in the local Universe may have been found. M60-UCD1 is most likely a tidally-stripped remnant of a more massive progenitor galaxy. Strader et al. predicts that the progenitor of M60-UCD1 was ~ 50-200 times more massive, suggesting that it was once an elliptical galaxy that has been stripped of most of its mass.
NASA is looking for a new mission for the damaged Kepler space telescope. Here are some ideas.
Sgr A* – the supermassive black hole sitting in the center of the Milky Way – is often referred to as a ‘starved’ black hole, meaning that it swallows very little of the nearby cosmic gas and dust. The authors of this paper observed Sgr A* with the Chandra X-ray telescope for 3 mega seconds, throughout which only 1% of the gas available to Sgr A* actually accreted onto the black hole. It swallows cold gas, while rejecting hot gas – ejecting the matter back into space.
The authors of today’s paper investigate the feeding habits of the elusive quiescent supermassive black hole, finding that in addition to swallowing some stars whole and constantly snacking on the winds of other stars, some black holes may also dine on giant stars slowly disrupted over tens to hundreds of orbits.
Previous authors have claimed that the black hole at the center of NGC 1365 is spinning extremely rapidly. But these claims are based on certain assumptions about the dominance of relativistic effects on the spectrum of NGC 1365. Risaliti et al., dig deeper into the spectral data of this X-ray source and use simulations to determine whether the signatures we see are caused by a rapidly-spinning black hole, or just cloudy (galactic) weather.
The authors discuss the possibility that the strangely-shaped supernova remnant W49B was created by a core-collapse supernova that formed strong bipolar jets instead of a spherical shockwave.
Observational surveys looking for the smallest super-massive black holes come up empty; could they be hiding in plain sight?
The race to be the first to detect gravitational waves is on – are pulsar timing arrays on the verge of a discovery? New predictions based on revised galaxy merger calculations suggest that it may be so.