Some active galactic nuclei (AGN) are surrounded by extended emission-line regions (EELRs), which trace both the illumination pattern of escaping radiation and its history over the light-travel time from the AGN to the gas. From a new set of such EELRs, we present evidence that the AGN in many Seyfert galaxies undergo luminous episodes 0.2–2×105 years in duration. Motivated by the discovery of the spectacular nebula known as Hanny’s Voorwerp, ionized by a powerful AGN which has appar-ently faded dramatically within ≈ 105 years, Galaxy Zoo volunteers have carried out both targeted and serendipitous searches for similar emission-line clouds around low-redshift galaxies. We present the resulting list of candidates and describe spectroscopy ide...
At the center of every galaxy there is a super-massive black hole of a million or more solar masses....
I investigate active supermassive black holes, also called active galactic nuclei (AGNs). My tool fo...
Context. Galaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisatio...
Some active galactic nuclei (AGN) are surrounded by extended emission-line regions (EELRs), which tr...
We present a narrow-band [O iii] imaging survey of 111 active galactic nucleus (AGN) hosts and 17 me...
Motivated by the discovery of large ionized clouds around AGN, and particularly the large fraction o...
In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we...
Using a sample of 39 Active Galactic Nuclei (AGN), we investigated the incidence of giant ionized cl...
The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies...
We present the results of a combined galaxy population analysis for the host galaxies of active gala...
I present the first results from the Close AGN Reference Survey (CARS, www.cars-survey.org) of 39 ne...
We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies tha...
Some galaxies emit excessive amounts of light from their centers, caused by accretion of gas onto su...
Spectroscopic studies of AGN are powerful means of probing the physical properties of the ionized ga...
We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accre...
At the center of every galaxy there is a super-massive black hole of a million or more solar masses....
I investigate active supermassive black holes, also called active galactic nuclei (AGNs). My tool fo...
Context. Galaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisatio...
Some active galactic nuclei (AGN) are surrounded by extended emission-line regions (EELRs), which tr...
We present a narrow-band [O iii] imaging survey of 111 active galactic nucleus (AGN) hosts and 17 me...
Motivated by the discovery of large ionized clouds around AGN, and particularly the large fraction o...
In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we...
Using a sample of 39 Active Galactic Nuclei (AGN), we investigated the incidence of giant ionized cl...
The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies...
We present the results of a combined galaxy population analysis for the host galaxies of active gala...
I present the first results from the Close AGN Reference Survey (CARS, www.cars-survey.org) of 39 ne...
We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies tha...
Some galaxies emit excessive amounts of light from their centers, caused by accretion of gas onto su...
Spectroscopic studies of AGN are powerful means of probing the physical properties of the ionized ga...
We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accre...
At the center of every galaxy there is a super-massive black hole of a million or more solar masses....
I investigate active supermassive black holes, also called active galactic nuclei (AGNs). My tool fo...
Context. Galaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisatio...