Search Publications
Circumstellar debris and pollution at white dwarf stars
Farihi, J.
Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence must have been produced during the white dwarf phase. This picture is strengthened by the signature of materia…
The first extrasolar planet detected via gravitational microlensing
Bond, Ian A.
In gravitational microlensing, distant planetary systems may be discovered by utilizing them as naturally occuring lenses. Efforts to find planets by this technique began in the 1990s. The first definitive detection of an extrasolar planet by microlensing was made in 2003 in the event OGLE 2003-BLG-235/MOA 2003-BLG-53, where the observed light cur…
The environments of short-duration gamma-ray bursts and implications for their progenitors
Berger, Edo
The study of short-duration gamma-ray bursts (GRBs) experienced a complete revolution in recent years thanks to the discovery of the first afterglows and host galaxies starting in May 2005. These observations demonstrated that short GRBs are cosmological in origin, reside in both star forming and elliptical galaxies, are not associated with supern…
Kinematics of the broad absorption line region in QSOs: Rotation and random motion
Popović, L. Č.; Antoniou, A.; Danezis, E. +2 more
Assuming that the Broad Absorption Line Region - BALR (originated in a disk wind) is composed of a number of successive independent absorbing density layers, which have apparent rotational and radial velocities and where ions have random velocities, we applied a model in order to obtain the kinematical parameters of BALR, by fitting the broad abso…
A molecular gas study of low luminosity radio galaxies
Prandoni, I.; Wilson, T. L.; de Ruiter, H. R. +3 more
We discuss CO spectral line data of a volume-limited sample of 23 nearby ( z < 0.03) low luminosity radio galaxies, selected from the B2 catalogue. We investigate whether the CO properties of our sample are correlated with the properties of the host galaxy, and in particular with the dust component. We find strong evidences for a physical link …
Witnessing the formation of a brightest cluster galaxy at z > 2
Ford, Holland C.; Miley, George K.; Overzier, Roderik A.
We present deep observations taken with the HST advanced camera for surveys of the central massive galaxy in a forming cluster at z = 2.2. The galaxy hosting the powerful radio source MRC 1138-262 is associated with one of the most extensive merger systems known in the early universe. Our HST/ACS image shows many star-forming galaxies merging with…
Ionized gas in starbursts: Case study of M82 and a note on NGC 1275
Gallagher, J. S.
Starbursts can be considered as galaxies where the normal self-regulation between the densities of young stars and the state of the ISM has broken down. This contribution briefly examines how intense modes of star formation influence the ISM, primarily as measured through properties of the warm ionized gas.
Winds from super star clusters: The interstellar environment in the starburst core of M82
Smith, L. J.; Westmoquette, M. S.
We present HST/STIS spectroscopy for two slit positions crossing the starburst core of M82, sampling both clusters and ionized gas at optical wavelengths. The spectra have a spatial resolution of ∼2 pc at M82, allowing us to probe the conditions within the starburst environment in unprecedented detail. The data provide new insights into young clus…
Black hole masses from reverberation mapping
Peterson, Bradley M.; Bentz, Misty C.
We review briefly how black hole masses are measured directly using reverberation mapping and indirectly through scaling relationships based on reverberation results, in particular through broad-line region radius-luminosity relationships. We discuss the nature and origin of uncertainties in these measurements, and outline current and future effor…
Stratification in the broad line region of AGN: The two-component model
Bon, E.; Popović, L. Č.; Ilić, D. +1 more
Here we present our investigation of the kinematic structure of the broad emission line region (BLR) in a sample of 14 single-peaked Active Galactic Nuclei (AGN), which have been previously observed in the X-ray (Fe Kα line) and where, according to the X-ray emission, a disk geometry is expected. To explain the BLR complex structure we apply a two…