Press Release: Black Hole Pretenders May Be Superfast-Spinning Pulsars

Press release on the Scientific American about our recent paper (led by Slavko Bogdaonov from Columbia University) on a transitional millisecond pulsar who behaves as a black hole impostor.


Are gravitational waves spinning down PSR J1023+0038?

The pulsar J1203+0038 rotates with a frequency ν ≈ 592 Hz and has been observed to transition between a radio state, during which it is visible as a millisecond radio pulsar, and and a Low Mass X-ray Binary state, during which accretion powered X-ray pulsations are visible. Timing during the two phases reveals that during... Continue Reading →

A Deep Pulse Search in Eleven Low Mass X-Ray Binaries

We present a systematic coherent X-ray pulsation search in eleven low mass X-ray binaries (LMXBs). We select a relatively broad variety of LMXBs, including persistent and transient sources and spanning orbital periods between 0.3 and 17 hours. We use about 3.6 Ms of data collected by the Rossi X-Ray Timing Explorer (RXTE) and XMM-Newton and... Continue Reading →

Fermi Paradox and Superintelligence 2: The Small Colonies Hypothesis

Let's resume our discussion on the implications of the Fermi paradox on superintelligence. As I said in my previous article, any civilization that masters space travel and achieves the possibility to build megastructures, must have developed superintelligence as a prerequisite. This consideration is based on an extrapolation of our current technological level and on reasonable... Continue Reading →

A Tidal Capture Formation Scenario for the Accreting Pulsar IGR J17480-2446 in Terzan 5

The low mass X-ray binary (LMXB) IGR J17480-2446 is an 11 Hz accreting pulsar located in the core of the globular cluster Terzan 5. This is a mildly recycled accreting pulsar with a peculiar evolutionary history since its total age has been suggested to be less than a few hundred Myr, despite the very old... Continue Reading →

A deceleration search for magnetar pulsations in the X-ray plateaus of short GRBs

A newly formed magnetar has been proposed as the central engine of short GRBs to explain on-going energy injection giving observed plateau phases in the X-ray lightcurves. These rapidly spinning magnetars may be capable of emitting pulsed emission comparable to known pulsars and magnetars. In this paper we show that, if present, a periodic signal... Continue Reading →

Further Evidence for a Weak Neutron Star Magnetosphere in the Accreting Millisecond X-Ray Pulsar HETE J1900.1-2455

HETE J1900.1--2455 is a peculiar accreting millisecond X-ray pulsar (AMXP) because it has shown intermittent pulsations after 22 days from the beginning of its outburst. The origin of intermittent pulses in accreting systems remains to be understood. To better investigate the phenomenon of intermittent pulsations here we present an analysis of 7 years of X-ray... Continue Reading →

Disc-jet coupling in low-luminosity accreting neutron stars

In outburst, neutron star X-ray binaries produce less powerful jets than black holes at a given X-ray luminosity. This has made them more difficult to study as they fade towards quiescence. To explore whether neutron stars power jets at low accretion rates (LX . 1036 erg s−1 ), we investigate the radio and X-ray properties... Continue Reading →

Create a free website or blog at

Up ↑