Related papers: Unobscured QSO2: A New Class of Objects?
We report the discovery of a high redshift, narrow emission-line galaxy identified in the optical follow-up of deep ROSAT fields. The object has a redshift of z=2.35 and its narrow emission lines together with its high optical and X-ray…
We present a cross-correlation between the ELAIS 15$\mu$m ISO survey with the {\it ROSAT} (0.1-2 keV) all-sky survey and the pointed observations WGACAT source catalogue. The resulting sample contains 15 objects. Optical spectroscopic…
We present XMM-Newton data centered on one of the MUNICS Near Infrared Cluster Survey fields (S2F1) and we discuss the X-ray properties of the 6 X-ray emitting EROs found. For one of them we have already obtained the redshift using…
We use UKIRT and ASCA observations to determine the nature of a high redshift (z=2.35) narrow-line AGN, previously discovered by Almaini et al. (1995). The UKIRT observations show a broad Halpha line while no Hbeta line is detected. This…
We present a sample of twenty-one ROSAT bright active galactic nuclei (AGN), representing a range of spectral classes, and selected for follow-up snap-shot observations with XMM-Newton. The typical exposure was between 5-10 ks. The objects…
The sky around the North Ecliptic Pole (NEP), at $\alpha$(2000) = 18$^h00^m00^s$, $\delta$(2000) = +66\degr33\arcmin39\arcsec, has the deepest exposure of the entire {\it ROSAT} All - Sky Survey (RASS). The NEP is an undistinguished region…
We present VLT near-IR spectroscopic observations of three X-ray sources characterized by extremely high X-ray-to-optical ratios (X/O>40), extremely red colors (6.3<R-K<7.4, i.e. EROs) and bright infrared magnitudes (17.6<K<18.3). These…
We present optical observations of two remarkable new AGN discovered by the Two-Micron All Sky Survey. Both are classified as QSOs based on their optical spectra, near-IR colors, and near-IR and [O III]5007 luminosities, but their optical…
The X-ray data around the North Ecliptic Pole (NEP) of the ROSAT All Sky Survey have been used to construct a contiguous area survey consisting of a sample of 445 individual X-ray sources above a flux of ~2x10^-14 erg cm^-2 s^-1 in the…
We present the results of a systematic analysis of the XMM-Newton spectra of nearby optically bright QSOs. The objects have been selected from X-ray Galaxy Catalog Xgal20. It is a catalog of 1172 manually identified and classified galaxies,…
We have conducted spectropolarimetry of 12 type II (obscured) quasar candidates selected from the spectroscopic database of the Sloan Digital Sky Survey based on their emission line properties. Polarization was detected in all objects, with…
We explore the X-ray properties of optically selected QSOs spectroscopically identified in the course of the 2dF QSO survey (2QZ). Our main goal is to expand to higher redshifts previous findings suggesting the presence of a fraction of…
We present the XMM-Newton and the optical-VLT spectra along with the optical and the near-infrared photometric data of one of the brightest X-ray (F(2-10 keV)~1e-13 erg/s cm^2) extremely red objects (R-K>=5) discovered so far. The source,…
New linear polarization measurements (mainly in the V band) are presented for 203 quasi-stellar objects (QSOs). The sample is made up of 94 QSOs located in the North Galactic Pole (NGP) region and of 109 QSOs in the South Galactic Pole…
Highly polarized QSOs discovered in the Two-Micron All Sky Survey (2MASS) have been observed to determine the source(s) of optical polarization in this near-infrared color-selected sample. Broad emission lines are observed in the polarized…
(Abridged) We present the results of the photometric and spectroscopic identification of 110 hard X-ray selected sources (6e-15<F(2-10 keV)<4e-14 cgs) from 5 additional XMM-Newton fields, nearly doubling the original HELLAS2XMM sample. We…
Optical broad-band polarimetry is presented for near-infrared color-selected AGN classified QSOs based on their K-band luminosity. More than 10% of a sample of 70 QSOs discovered in the Two Micron All Sky Survey (2MASS) with J-K > 2 and M_K…
We present optical candidates for 75 X-ray sources in a $\sim 1$ deg$^2$ overlapping region with the medium deep ROSAT survey. These candidates are selected using the multi-color CCD imaging observations made for the T329 field of the…
This paper presents the analysis of a statistically complete sample of 28 serendipitous X-ray sources selected in 82 pointed XMM-Newton fields down to a count-rate of 0.002 counts s^-1(4.5-7.5 keV energy band). This is the first sample…
Recently, Zakamska et al. (2003) selected 291 high-ionization narrow emission-line AGN in the redshift range 0.3-0.83 from the Sloan Digital Sky Survey spectroscopic data. The sample includes both Seyfert II galaxies and their higher…