445 citations · 1.9k across the 43 of their papers we have counts for
8 papers · 2 filters
X-rays from the First Massive Black Holes
W. N. Brandt, C. Vignali, B. D. Lehmer +3
We briefly review some recent results from Chandra and XMM-Newton studies of the highest redshift (z > 4) active galactic nuclei (AGNs). Specific topics covered include radio-quiet…
A Chandra observation of the z=2.285 galaxy FSC10214+4724: Evidence for a Compton-thick quasar?
D. M. Alexander, G. Chartas, F. E. Bauer +3
We present a ~20 ks Chandra ACIS-S observation of the strongly lensed z=2.285 ultra-luminous infrared galaxy FSC10214+4724. Although this observation achieves the equivalent sensit…
Obscured accreting black holes at high redshift
A. Comastri, F. Fiore, C. Vignali +2
A significant fraction of the accreting black holes powering high redshift AGN are obscured by large columns of dust and gas. For this reason, luminous type 2 quasars can be effici…
Type II quasar candidates in the Sloan Digital Sky Survey: evidence for X-ray obscuration
C. Vignali, D. M. Alexander, A. Comastri
Recent X-ray surveys with Chandra and XMM-Newton have found several genuine Type II quasars, the long sought-after population of high-luminosity (high-redshift) Seyfert 2 galaxies,…
XMM-Newton observations of Extremely Red Objects and the link with luminous, X-ray obscured Quasars
M. Brusa, A. Comastri, E. Daddi +8
We present the results of a deep (about 80 ks) XMM-Newton survey of the largest sample of near-infrared selected Extremely Red Objects (R-K>5) available to date to K_S< 19.2. At th…
Evidence for X-ray Obscuration in Type II Quasar Candidates from the Sloan Digital Sky Survey
C. Vignali, D. M. Alexander, A. Comastri
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 samp…