Search Publications
Kinematics of stellar associations: the epicycle approximation and the convergent point method
Olling, Rob P.; Makarov, Valeri V.; Teuben, Peter J.
Employing analytical and numerical tools, we expound the Galactic epicycle theory to describe the kinematic evolution of stellar, gravitationally unbound associations in the vicinity of the Sun. We estimate the limits of applicability of the analytical epicycle approximation and harmonic vertical motion by numerical integration of test orbits with…
CIRPASS near-infrared integral-field spectroscopy of massive star clusters in the starburst galaxy NGC 1140
O'Connell, R. W.; Gallagher, J. S.; Smith, L. J. +6 more
We analyse near-infrared integral field spectroscopy of the central starburst region of NGC 1140, obtained at the Gemini-South telescope equipped with CIRPASS. Our ~1.45-1.67µm wavelength coverage includes the bright [FeII]λ 1.64-µm emission line, as well as high-order Brackett (hydrogen) lines. While strong [FeII] emission, thought to…
On the variability of the iron Kα line in Mrk 841
Nandra, K.; Petrucci, P. O.; Longinotti, A. L. +1 more
Petrucci et al. have recently reported the extraordinary behaviour of the iron Kα line in the Type I active galactic nucleus Mrk 841. At the XMM-Newton/EPIC resolution, a narrow line was observed in a short observation, which then apparently disappeared around 0.5 d later when another observation was performed. The limits are such that the line ca…
The dwarf galaxy population in Abell 2218
Driver, Simon P.; De Propris, Roberto; Nulsen, Paul E. J. +2 more
We present results from a deep photometric study of the rich galaxy cluster Abell 2218 (z= 0.18) based on archival Hubble Space Telescope WFPC2 F606W images. These have been used to derive the luminosity function to extremely faint limits (MF606W~-13.2 mag, µ0~ 24.7 mag arcsec-2) over a wide field of view (1.…
A giant molecular cloud falling through the heart of Cygnus A: clues to the triggering of the activity
Tadhunter, C. N.; Bellamy, M. J.
We present intermediate-resolution near-infrared long-slit spectroscopic data for the nearby radio galaxy Cygnus A (3C 405) (obtained with the NIRSPEC spectrograph on the Keck II telescope). The data reveal considerable complexity in the near-infrared emission-line kinematics, including line splittings of 200-350 km s-1 and a mixture of…
An intense soft excess and evidence for light bending in the luminous narrow-line quasar PHL 1092
Brandt, W. N.; Fabian, A. C.; Boller, Th. +2 more
The narrow-line quasar PHL 1092 was observed by XMM-Newton at two epochs separated by nearly 30 months. Timing analyses confirm the extreme variability observed during previous X-ray missions. A measurement of the radiative efficiency is in excess of what is expected from a Schwarzschild black hole. In addition to the rapid X-ray variability, the …
The XMM-Newton/2dF survey - IV. The X-ray spectral properties of the hard sources
Georgakakis, A.; Georgantopoulos, I.; Shanks, T. +4 more
We present an analysis of the X-ray spectral properties of 61 hard X-ray-selected (2-8 keV) sources from the bright (f2-8keV > 10-14 erg cm-2 s-1)XMM-Newton/2dF survey. This comprises nine XMM-Newton pointings in the North Galactic Pole region (~1.6 deg2) and overlaps with the SDSS, 2QZ and…
An active M8.5 dwarf wide companion to the M4/DA binary LHS 4039/LHS 4040
Schwope, A.; Lodieu, N.; Scholz, R. -D. +4 more
Low-mass and brown dwarfs have recently been found as wide companions to many nearby stars, formerly believed to be single. Wide binaries are usually found as common proper motion pairs. Sometimes, more than two objects share the same large proper motion, identifying them as nearby systems. We have found a third, low-mass component to a known wide…
Present-day scaling relations for submillimetre galaxies: the origin of spheroidal systems
Takagi, T.; Hanami, H.; Arimoto, N.
We analyse the spectral energy distributions (SEDs) of 23 submillimetre galaxies and three ISO-detected extremely red objects, all of which have the spectroscopic redshifts, using an evolutionary SED model of starbursts. This SED model allows us to investigate the intrinsic properties of starbursts, such as the starburst age and the mean stellar m…
Identifying young gamma-ray burst fossils
Ramirez-Ruiz, Enrico
The recent reports of temporal and spectral peculiarities in the early stages of some afterglows suggest that we may be wrong in postulating a central engine that becomes dormant after the burst itself. A continually decreasing post-burst relativistic outflow, such as put out by a decaying magnetar, may continue to be emitted for periods of days o…