Related papers: M31 and Local Group QSO's

The aim is to investigate the region of the sky around NGC4410/Mrk1325 for objects which are physically associated with this active, double nucleus galaxy. We use archived data to study the placement, brightness, X-ray properties and…

We report new, as yet unpublished HST/WFPC2 V, I photometry of 9 globular clusters in M31. These are part of a total sample of 19 clusters on M31 with well observed CMDs from HST. The clusters have the full range of horizontal branch…

We present high-resolution imaging and low-resolution spectroscopy of the BL Lac object PKS 0537-441 (z = 0.893) and its environment. The observations were designed to clarify, whether the properties of PKS 0537-441 are affected by…

We have conducted an optical study of the environments of seven radio-loud quasars at redshifts 1<z<1.6. In this paper we describe deep B and R band images obtained for fields of $\sim6\times$6 arcmin around these quasars with 3$\sigma$…

An order of magnitude more dwarf galaxies are expected to inhabit the Local Group, based on currently accepted galaxy formation models, than have been observed. This discrepancy has been noted in environments ranging from the field to rich…

The Local Group is a unique environment in which to study the astrophysics of galaxy formation. The proximity of the Milky Way and M31 enhances the frequency of interactions of the low-mass halo population with more massive dark matter…

It is suggested that many of the ultraluminous compact x-ray sources now being found in the main bodies of galaxies, particularly those that are active, like M82, NGC 3628 and others, are "local" QSOs, or BL Lac objects, with high intrinsic…

We compare a deep (37 ks) Chandra ACIS-S image of the M31 bulge to deep [O III] Local Group Survey data of the same region. Through precision image alignment using globular cluster X-ray sources, we are able to improve constraints on…

Over the last few years, rapid progress has been made in distance measurements for nearby galaxies based on the magnitude of the tip of red giant branch stars. Current CCD surveys with HST and large ground- based telescopes bring…

We investigate low mass X-ray binaries (LMXBs) in the M31 globular cluster (GC) system using data from the 2XMMi catalogue. These X-ray data are based on all publicly available XMM-Newton observations of the galaxy. This new survey provides…

We report our new observations of redshifted carbon monoxide emission from six z~6 quasars, using the PdBI. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations…

The ultra-luminous X-ray source (ULX) M82 X-1 is one of the most promising intermediate mass black hole candidates in the local universe based on its high X-ray luminosities ($10^{40}-10^{41} {\rm erg s^{-1}}$) and quasi-periodic…

We have conducted a search of a 9 deg$^{2}$ region of the CFHTLS around the Milky Way analog M101 (D$\sim$7 Mpc), in order to look for previously unknown low surface brightness galaxies. This search has uncovered 38 new low surface…

We present the first detection of 24 {\mu}m variability in 24 sources in the Local Group galaxy M33. These results are based on 4 epochs of MIPS observations, which are irregularly spaced over ~750 days. We find that these sources are…

We report the first detection of emission line gas within the host galaxies of high redshift QSOs. This was done using narrow-band imaging at the redshifted wavelengths of [O III] and H alpha, using the PUEO adaptive optics camera of the…

We present a new study of archival ALMA observations of the CO(2-1) line emission of the host galaxy of quasar RX J1131 at redshift $z$=0.654, lensed by a foreground galaxy. A simple lens model is shown to well reproduce the optical images…

Three high-redshift (z=2) and high luminosity (M_B < -28 mag for Ho = 50, qo=0.5) QSOs, two radio-quiet one radio-loud, were imaged in R, I and K bands. The luminosities, colours and sizes of the hosts overlap with those of actively…

We have identified galaxies near two quasars which are at the redshift of damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both galaxies are actively forming stars. One galaxy has a luminosity close to the break in the…

Large-scale surveys over the last years have revealed about 300 QSOs at redshift above 6. Follow-up observations identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas…

We obtained follow-up HST observations of the seven low surface brightness galaxies discovered with the Dragonfly Telephoto Array in the field of the massive spiral galaxy M101. Out of the seven galaxies, only three were resolved into stars…