Search Publications

Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

Costa, E.; Altamirano, D.; Degenaar, N. +8 more

We investigate the thermonuclear bursting behaviour of IGR J17473-2721, an X-ray transient that in 2008 underwent a 6-month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, Rossi X-ray Timing Explorer (RXTE) and the INTErnational Gamma-Ray Astrophysic…

Long-term Radiative Behavior Of SGR 1900+14

Kouveliotou, Chryssa; Göǧüş, Ersin; Güver, Tolga +2 more

The prolific magnetar SGR 1900+14 showed two outbursts in the last decade and has been closely monitored in the X-rays to track the changes in its radiative properties. We use archival Chandra and XMM-Newton observations of SGR 1900+14 to construct a history of its spectrum and persistent X-ray flux spanning a period of about seven years. We show …

Spectral Energy Distribution of z >~ 1 Type Ia Supernova Hosts in GOODS: Constraints on Evolutionary Delay and the Initial Mass Function

Chary, R. R.; Thomson, M. G.

We identify a sample of 22 host galaxies of Type Ia Supernovae (SNe Ia) at redshifts 0.95 < z < 1.8 discovered in the Hubble Space Telescope (HST) observations of the Great Observatories Origins Deep Survey (GOODS) fields. We measure the photometry of the hosts in Spitzer Space Telescope and ground-based imaging of the GOODS fields to provid…

Very Large Telescope Interferometer observations of the dust geometry around R Coronae Borealis stars

Gallagher, J. S.; Chesneau, O.; De Marco, O. +4 more

We are investigating the formation and evolution of dust around the hydrogen-deficient supergiants known as R Coronae Borealis (RCB) stars. We aim to determine the connection between the probable merger past of these stars and their current dust-production activities.

We carried out high angular resolution interferometric observations of thre…

VII Zw 403: H I Structure in a Blue Compact Dwarf Galaxy

Östlin, Göran; Brinks, Elias; Elmegreen, Bruce G. +9 more

We present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s^-1, but rises to ~20 km s^-1 after correctio…

A strongly star-forming group: three massive galaxies associated with a quasi-stellar object

Ivison, R. J.; Ebrero, J.; Page, M. J. +4 more

We present here photometric redshift confirmation of the presence of large-scale structure around the z= 1.82 quasi-stellar object (QSO) RX J0941, which shows an overdensity of submillimetre (submm) sources. Radio imaging confirms the presence of the submm sources and pinpoints their likely optical near-infrared (NIR) counterparts. Four of the fiv…

3C 390.3: more stable evidence that the double-peaked broad Balmer lines originate from an accretion disc near a central black hole

Zhang, Xue-Guang

In this paper, we study the structure of the broad emission-line regions (BLRs) of the well-known double-peaked emitter (an active galactic nucleus with broad double-peaked low-ionization emission lines) 3C 390.3. Besides the best-fitting results for the double-peaked broad optical Balmer lines of 3C 390.3 obtained from the theoretical disc model,…

Is Calvera a Gamma-Ray Pulsar?

Halpern, J. P.

Originally selected as a neutron star (NS) candidate in the ROSAT All-Sky Survey, 1RXS J141256.0+792204 ("Calvera") was discovered to be a 59 ms X-ray pulsar in a pair of XMM-Newton observations by Zane et al. Surprisingly, their claimed detection of this pulsar in Fermi γ-ray data requires no period derivative, severely restricting its dipole mag…

The XMM-Newton survey of the Small Magellanic Cloud: discovery of the 11.866 s Be/X-ray binary pulsar XMMU J004814.0-732204(SXP11.87)

Pietsch, W.; Haberl, F.; Hatzidimitriou, D. +12 more

Aims: One of the goals of the XMM-Newton survey of the Small Magellanic Cloud is to study the Be/X-ray binary population. During one of our first survey observations, a bright new transient - XMMU J004814.0-732204 - was discovered.
Methods: We present the analysis of the EPIC X-ray data, together with optical observations, to investigate…

Study of the Poynting Flux in Active Region 10930 Using Data-driven Magnetohydrodynamic Simulation

Zhu, X. S.; He, H.; Wang, H. N. +1 more

Powerful solar flares are closely related to the evolution of magnetic field configuration on the photosphere. We choose the Poynting flux as a parameter in the study of magnetic field changes. We use time-dependent multidimensional MHD simulations around a flare occurrence to generate the results, with the temporal variation of the bottom boundar…