Related papers: CLASS: Coronal Line Activity Spectroscopic Survey
We present Chandra observations of nine high-redshift quasars (z=2.7-5.9) discovered by the Sloan Digital Sky Survey with weak or undetectable high-ionization emission lines in their UV spectra (WLQs). Adding archival X-ray observations of…
We selected 27244 nearby, red, giant early-type galaxies (RGEs) from the Sloan Digital Sky Survey (SDSS). In a large fraction (53%) of their spectra the [O III] emission line is detected, with an equivalent width (EW) distribution strongly…
We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically detected SDSS sources with redshift measurements,…
Mid-resolution spectra are used to deduce the size and kinematics of the coronal gas in a sample of Seyfert galaxies by means of observations of the [FeXI], [FeX], [FeVII], [SiVI] and [SiVII] lines. These coronal lines (CL) extend from the…
Methods: We analyse an XMM-Newton observation of 1RXS J115928.5-524717, an ultracool dwarf with spectral type M9 and compare its X-ray properties to those of other similar very late-type stars. Results: We clearly detected 1RXS…
Merging luminous galaxies are ideal laboratories to study some of the most extreme astrophysical phenomena. The local (z=0.1232) obscured quasar J1356+1026 has two nuclei, North and South (J1356N and J1356S), but despite numerous efforts,…
We present new spectroscopic and photometric follow-up observations of the known sample of extreme coronal line emitting galaxies (ECLEs) identified in the Sloan Digital Sky Survey (SDSS). With these new data, observations of the ECLE…
There is substantial evidence for a connection between star formation in the nuclear region of a galaxy and growth of the central supermassive black hole. Furthermore, starburst activity in the region around an active galactic nucleus (AGN)…
The relative Doppler velocities and linewidths in a polar coronal hole and the nearby quiet-Sun region have been obtained from the {\it Solar and Heliospheric Observatory} (SOHO)/{\it Coronal Diagnostic Spectrometer} (CDS) observations…
The bulk of the X-ray emission in Active Galactic Nuclei (AGN) is produced very close to the accreting supermassive black hole (SMBH), in a corona of hot electrons which up scatters optical and ultraviolet photons from the accretion flow.…
Sun-as-a-star coronal plasma composition, derived from full-Sun spectra, and the F10.7 radio flux (2.8 GHz) have been shown to be highly correlated (r = 0.88) during solar cycle 24. However, this correlation becomes nonlinear during…
We present a pilot study of the X-ray properties of intermediate-mass (~10^5-10^6 M_sun) black holes in active galaxies using the Chandra X-ray telescope. Eight of the 10 active galaxies are detected with a significance of at least 3 sigma,…
We present the detections of CO line emission in the central galaxy of sixteen extreme cooling flow clusters using the IRAM 30m and the JCMT 15m. These detections of CO(1-0), CO(2-1), CO(3-2) and CO(4-3) are consistent with the presence of…
Most of the optically classified low ionisation narrow emission-line regions (LINERs) nuclei host an active galactic nuclei (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. The aims of this work are…
We present a spectroscopic analysis of nearly 8000 late-type dwarfs in the Sloan Digital Sky Survey. Using the Halpha emission line as an activity indicator, we investigate the fraction of active stars as a function of spectral type and…
We have measured coronal line emission for a sample of 19 Narrow-Line Seyfert~1 galaxies. Kinematic analysis shows that the Coronal Line Region (CLR) consists of gas in a decelerating outflow. We intend to use these data as a test of the…
JWST spectroscopy has built large emission line samples at $z\gtrsim4$, but it has yet to confidently reveal many galaxies with the hard radiation fields commonly associated with AGN photoionization. While this may indicate a weaker UV…
Potential Field Source Surface (PFSS) models are widely used to study the solar corona and form the basis for solar wind forecasting, yet often fail to reproduce observed properties of coronal holes. We analyze 702 observed coronal holes…
Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum White-Light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona)…
We examine the 10\m\ emission of the central regions of 281 spiral galaxies, after having compiled all ground-based, small-aperture ($\sim$5") broad-band photometric observations at \l$\sim$10\m\ (N magnitudes) published in the literature.…