Stefanie Komossa

The X-Ray Point-Source Population of NGC 1365: The Puzzle of Two Highly-Variable Ultraluminous X-ray Sources (2008)

Also archived in arXiv:0811.1037 v1 Nov 7, 2008

Strateva, Iskra V., Komossa, Stefanie

We present 26 point-sources discovered with Chandra within 200" (~20kpc) of the center of the barred supergiant galaxy NGC 1365. The majority of these sources are high-mass X-ray binaries, containing...

Hypercompact Stellar Systems Around Recoiling Supermassive Black Holes (2008)

Merritt, David, Schnittman, Jeremy, Komossa, Stefanie

Archived in: arXiv:0809.5046 v2 6 Oct 2008

Hypercompact Stellar Systems Around Recoiling Supermassive Black Holes (2008)

Merritt, David, Schnittman, Jeremy D., Komossa, Stefanie

A supermassive black hole ejected from the center of a galaxy by gravitational wave recoil carries a retinue of bound stars - a "hypercompact stellar system" (HCSS). The numbers and properties of...

First detection of hard X-ray photons in the soft X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: The X-ray photon distribution observed by Swift (2008)

Grupe, Dirk, Leighly, Karen M., Komossa, Stefanie

We report on the first detection of hard X-ray photons (E>2.5 keV) in the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007 which was the AGN with the softest X-ray spectrum during the ROSAT...

Tidal disruption flares from recoiling supermassive black holes (2008)

Tidal Disruption Flares from Recoiling Supermassive Black Holes (2008)

Also archived in: arXiv:0807.0223 v1 Jul 1 2008

XMM-Newton observations of the Narrow-Line Seyfert 1 galaxy Mrk 335 in an historical low X-ray flux state (2008)

Supermassive black holes ejected from galaxy nuclei by gravitational wave recoil will carry a retinue of bound stars, even in the absence of an accretion disk. We discuss the observable signatures...

Grupe, Dirk, Komossa, Stefanie, Gallo, Luigi C., Fabian, Andrew C., Larsson, Josefin, Pradhan, Anil K., ...

We report the discovery of strong soft X-ray emission lines and a hard continuum above 2 keV in the Narrow-Line Seyfert 1 galaxy Mrk 335 during an extremely low X-ray flux state. Mrk 335 was observed...

Die Enträtselung des Universums (2008)

XMM-Newton observations of the narrow-line Seyfert 1 galaxy Mrk 335 in a historical low X-ray flux state (2008)

Studium Generale Vorlesung im WiSe 2007-2008; Dienstag, 08. Januar 2008

Grupe, Dirk, Komossa, Stefanie, Gallo, Luigi C., Fabian, Andrew C., Larsson, Josefin, Pradhan, Anil K., ...

Chandra LETGS spectroscopy of the quasar MR 2251−178 and its warm absorber (2008)

Ramírez, R. M., Komossa, Stefanie, Burwitz, Vadim, Mathur, Smita

CHANDRA LETGS spectroscopy of ionized absorbers: the quasar MR 2251-178 (2008)

Ramírez, J. M., Komossa, Stefanie, Burwitz, Vadim, Mathur, Smita

The density of the narrow-line region of type 1 active galactic nuclei (2008)

Xu, Dawei, Komossa, Stefanie, Zhou, Hongyan

Tidal disruption flares from recoiling supermassive black holes (2008)

The density of the narrow-line region of type 1 Active Galactic Nuclei (2008)

Dawei Xu, Hongyan Zhou, Stefanie Komossa

We utilize the diagnostic power of the [S II] λλ6716,6731 intensity ratio to measure the density of the narrowline region (NLR) systematically for a large sample of narrow-line Seyfert 1...

Chandra Letgs spectroscopy of ionized absorbers: The quasar MR 2251-178 (2008)

J. M. Ramírez, Smita Mathur, Stefanie Komossa, Vadim Burwitz

This flux implies that the nuclear source of MR 2251-178 is in a relatively low state. We did not find evidence for an extra cold material in the line of sight, that would be associated to the giant...

First detection of hard X-ray photons in the soft X-ray transient narrow-line Seyfert 1 galaxy WPVS 007: the X-ray photon distribution observed by Swift (2008)

Grupe, Dirk, Leighly, Karen M., Komossa, Stefanie

Discovery of the Narrow-Line Seyfert 1 galaxy Mkn 335 in an historical low X-ray flux state (2007)

Grupe, Dirk, Komossa, Stefanie, Gallo, Luigi

We report the discovery of the Narrow-Line Seyfert 1 galaxy Mkn 335 in an extremely low X-ray state. A comparison of Swift observations obtained in May and June/July 2007 with all previous X-ray...

The narrow-line region of narrow-line and broad-line type 1 AGN I. A zone of avoidance in density (2007)

Xu, Dawei, Komossa, Stefanie, Zhou, Hongyan, Wang, Tinggui, Wei, Jianyan

The properties of narrow-line Seyfert 1 (NLS1) galaxies, the links and correlations between them, and the physics behind them, are still not well understood. Apart from accretion rates and black hole...

A narrow line Seyfert 1--blazar composite nucleus in 2MASX J0324+3410 (2007)

Zhou, Hongyan, Wang, Tinggui, Yuan, Weimin, Shan, Hongguang, Komossa, Stefanie, Lu, Honglin, ...

We report the identification of 2MASX J032441.19+341045.9 (hereafter 2MASX J0324+3410) with an appealing object which shows the dual properties of both a narrow line Seyfert 1 galaxy (NLS1) and a...

An Update on the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: Swift observations of UV variability and persistence of X-ray faintness (2007)

Grupe, Dirk, Schady, Patricia, Leighly, Karen M., Komossa, Stefanie, O'Brien, Paul, Nousek, John A.

We report on the detection of UV variability and the persistence of X-ray faintness of the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007 based on the first year of monitoring this AGN with...

A narrow-line Seyfert 1-blazar composite nucleus in 2MASX J0324+3410 (2007)

Zhou, Hongyan, Wang, Tinggui, Yuan, Weimin, Shan, Hongguang, Komossa, Stefanie, Lu, Honglin, ...

An update on the X-ray transient narrow-line Seyfert 1 galaxy WPVS 007: swift observations of UV variability and persistence of X-ray faintness (2007)

Grupe, Dirk, Schady, Patricia, Leighly, Karen M., Komossa, Stefanie, O'Brien, Paul T., Nousek, John A.

The relation between the properties of the NLR in narrow-line Seyfert 1 galaxies and the accretion rate (2007)

Xu, Dawei, Komossa, Stefanie

Discovery of the narrow-line Seyfert 1 galaxy Markarian 335 in a historical low X-ray flux state (2007)

Grupe, Dirk, Komossa, Stefanie, Gallo, Luigi C.

Properties of the Narrow-line region in Seyfert galaxies (2007)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

The narrow-line region of narrow-line and broad-line type 1 active galactic nuclei - I. A zone of avoidance in density (2007)

Xu, Dawei, Komossa, Stefanie, Zhou, Hongyan, Wang, Tinggui, Wei, Jianyan

Properties of the Narrow-Line Region in Seyfert Galaxies (2006)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

We study the narrow-line region (NLR) of six Seyfert-1 and six Seyfert-2 galaxies by means of spatially resolved optical spectroscopy and photoionization modelling. From spatially resolved spectral...

Size and properties of the narrow-line region in Seyfert-1 galaxies from spatially-resolved optical spectroscopy (2006)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

Spatially resolved emission-line spectroscopy is a powerful tool to determine the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical...

Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy (2006)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding...

Swift Observations of the highly X-ray variable Narrow Line Seyfert 1 galaxy RX J0148.3-2758 (2006)

Grupe, Dirk, Leighly, Karen M., Komossa, Stefanie, Schady, Patricia, O'Brien, Paul T., Burrows, Davis N., ...

We report on Swift observations of the Narrow-Line Seyfert 1 galaxy (NLS1) RX J0148.3--2758. It was observed for 41.6 ks in 2005 May and for 15.8 ks in 2005 December. On short as well as on long...

The radio-loud narrow-line quasar SDSS J172206.03+565451.6 (2006)

Komossa, Stefanie, Voges, Wolfgang, Adorf, Hans-Martin, Xu, Dawei, Mathur, Smita, Anderson, Scott F.

Radio-loud narrow-line type 1 quasars (2006)

Komossa, Stefanie, Voges, Wolfgang, Xu, Dawei, Mathur, Smita, Adorf, Hans-Martin, Lemson, Gerard, ...

Radio-loud narrow-line type 1 quasars (2006)

Komossa, Stefanie, Voges, Wolfgang, Xu, Dawei, Mathur, Smita, Adorf, Hans-Martin, Lemson, Gerard, ...

Swift observations of the highly X-ray variable narrow-line seyfert 1 galaxy RX J0148.3-2758 (2006)

Grupe, Dirk, Leighly, Karen M., Komossa, Stefanie, Schady, Patricia, O'Brien, Paul T., Burrows, David N., ...

Studying size and physical properties of the narrow-line region in active galaxies (2006)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

X-ray and Gamma-ray properties of AGN: results from XMM-Newton, Chandra and INTEGRAL (2006)

A systematic search of highly variable X-ray sources with the XMM-Newton serendipitous survey (2006)

Yuan, Weimin, Osborne, Julian P., Watson, Mike G., Komossa, Stefanie

Size and Properties of the NLR in the Seyfert-2 Galaxy NGC 1386 (2005)

Bennert, Nicola, Jungwiert, Bruno, Komossa, Stefanie, Haas, Martin, Chini, Rolf

We study the narrow-line region (NLR) of the Seyfert-2 galaxy NGC 1386 by means of long-slit spectroscopy obtained with FORS1 at the VLT. We use the galaxy itself for subtracting the stellar...

Super-solar Metallicity in the NLS1 Galaxy Markarian 1044 (2005)

Fields, Dale L., Mathur, Smita, Pogge, Richard W., Nicastro, Fabrizio, Komossa, Stefanie, Krongold, Yair

The determination of the bulk metallicity and the abundance mixture of various elements is very difficult in quasars and AGNs because only a few lines are observed and the ionization correction is...

Supersolar N/C in the narrow-line Seyfert 1 galaxy markarian 1044 (2005)

Fields, Dale L., Mathur, Smita, Pogge, Richard W., Nicastro, Fabrizio, Komossa, Stefanie

Supersolar metallicity in the NLS1 galaxy markarian 1044 (2005)

Fields, Dale L., Mathur, Smita, Pogge, Richard W., Nicastro, Fabrizio, Komossa, Stefanie, Krongold, Yair

Super-solar N/C in the NLS1 Galaxy Markarian 1044 (2004)

Fields, Dale L., Mathur, Smita, Pogge, Richard W., Nicastro, Fabrizio, Komossa, Stefanie

Narrow-Line Seyfert 1s (NLS1s) are known to have extreme values of a number of properties compared to Active Galactic Nuclei (AGN) as a class. In particular, previous emission-line studies have...

A huge drop in the X-ray luminosity of the nonactive galaxy RX J1242.6-119A, and the first postflare spectrum: testing the tidal disruption scenario (2004)

Komossa, Stefanie, Halpern, Jules, Schartel, Norbert, Hasinger, Günther, Santos-Lleo, Maria, Predehl, Peter

Winds and outflows in starburst galaxies and AGN (2004)

Komossa, Stefanie, Hasinger, Günther, Schulz, Hartmut

Absorption components in the nucleus of NGC 3227 (2004)

Xu, Dawei, Komossa, Stefanie, Burwitz, Vadim, Predehl, Peter

Winds and Outflows in Starburst Galaxies and AGN (2003)

Komossa, Stefanie, Hasinger, Guenther, Schulz, Hartmut

Winds and outflows in starburst galaxies and AGN provide important information on the physics of the "central engine", the presence and evolution of (nuclear) starbursts, and the metal enrichment of...

Observational evidence for supermassive black hole binaries (2003)

An AGN Sample with High X-ray-to-optical Flux Ratio from RASS II.Optical Emission Line Properties of Seyfert 1 Type AGN (2003)

Coalescing massive black hole binaries are powerful emitters of gravitational waves, in the LISA sensitivity range for masses M_BH ~ 10^{4-7} M_sun. According to hierarchical galaxy merger models,...

Xu, D. W., Komossa, Stefanie, Wei, J. Y., Qian, Y., Zheng, X. Z.

This work studies the optical emission line properties of a sample of 155 low-redshift bright X-ray selected ROSAT Seyfert~1 type AGN for which adequate signal-to-noise ratio spectroscopic...

X-ray imaging and spectroscopy of (radio-quiet) AGN: Highlights from Chandra and XMM-Newton (2003)

X-ray outbursts from nearby 'normal' and active galaxies : A review, new radio observations, and an X-ray search for further tidal disruption flares (2003)

The X-ray observatories XMM-Newton and Chandra provided a wealth of exciting new results. Chandra delivered X-ray images of outstanding detail, reaching subarcsecond spatial resolution for the first...

Komossa, Stefanie, Dahlem, Michael

An active galactic nucleus sample with high X-ray-to-optical flux ratio from RASS. II. Optical emission line properties of Seyfert 1-type active galactic nuclei (2003)

Xu, D. W., Komossa, Stefanie, Wei, J. Y., Zheng, X. Z.

A new X-ray probe for supermassive black holes in non-active galaxies (2003)

Komossa, Stefanie, Xu, Dawei, Wei, Jianyan

Das Xinglong-Observatorium in Chinas Yan-Bergen (2003)

Observational evidence for supermassive black hole binaries (2003)

A spectral analysis of 155 Seyfert 1 type AGN (2003)

Xu, Da-wei, Komossa, Stefanie, Wei, Jian-yan, Qian, Yi, Zheng, Xian-zhong

X-ray imaging and spectroscopy of (radio-quiet) AGN: highlights from Chandra and XMM-Newton (2003)

AGN and starburst components of the ULIRG NGC 6240: the Chandra high-resolution view (2003)

Entdeckung eines Paares Schwarzer Loecher im Zentrum der Galaxie NGC 6240 (2003)

Komossa, Stefanie, Hasinger, Guenther, Burwitz, Vadim, Predehl, Peter

A black hole twin-pack (2003)

Hasinger, Günther, Komossa, Stefanie

Giant-amplitude X-ray flares as probes of the black hole region of nearby galaxies (2003)

Komossa, Stefanie, Yuan, Weimin, Xu, Da Wei

Discovery of a binary AGN in the ultraluminous infrared galaxy NGC 6240 using Chandra (2002)

Komossa, Stefanie, Burwitz, Vadim, Hasinger, Guenther, Predehl, Peter, Kaastra, Jelle S., Ikebe, Yasushi

Ultraluminous infrared galaxies (ULIRGs) are outstanding due to their huge luminosity output in the infrared, which is predominantly powered by super starbursts and/or hidden active galactic nuclei...

X-ray Evidence for Supermassive Black Holes at the Centers of Nearby Galaxies (2002)

The X-ray evolving universe: (ionized) absorption and dust, from nearby Seyfert galaxies to high-redshift quasars (2002)

We first present a short overview of X-ray probes of the black hole region of active galaxies (AGN) and then concentrate on the X-ray search for supermassive black holes (SMBHs) in optically...

Komossa, Stefanie, Hasinger, Guenther

(Abridged) Cold and warm absorbers have beeen detected in all types of active galaxies (AGN) from low to high redshift. This gas, located in the black hole region of AGN, is thought to play an...

X-ray evidence for supermassive black holes in non-active galaxies: Detection of x-ray flare events, interpreted as tidal disruptions of stars by SMBHs (2002)

X-ray evidence for supermassive black holes at the centers of nearby, non-active galaxies (2002)

X-rays from the environment of supermassive black holes in active galaxies (2002)

The X-ray evolving universe: (ionized) absorption and dust, from nearby Seyfert galaxies to high-redshift quasars (2002)

Komossa, Stefanie, Hasinger, Günther

X-ray spectroscopy of NGC 3227: ROSAT and Chandra results (2002)

Wenn ein Schwarzes Loch einen Stern verschluckt... (2002)

Rätselhaft Eisenfabrik im Universum (2002)

Hasinger, Guenther, Komossa, Stefanie

X-ray Evidence for Supermassive Black Holes in Non-Active Galaxies. Subtitle: Detection of X-ray Flare Events, Interpreted as Tidal Disruptions of Stars by SMBHs (2001)

X-ray outbursts from nearby `normal' and active galaxies. A review, new radio observations, and an X-ray search for further tidal disruption flares (2001)

It has long been suggested that supermassive black holes in non-active galaxies might be tracked down by occasional tidal disruptions of stars on nearly radial orbits. A tidal disruption event would...

Komossa, Stefanie, Dahlem, Michael

In the last few years, giant-amplitude, non-recurrent X-ray flares have been observed from several non-active galaxies (NGC 5905, RXJ1242-11, RXJ1624+75, RXJ1420+53, RXJ1331-32). All of them share...

The X-ray properties of the low-redshift quasar MRC 2251-178 and its environment: some surprises (2001)

Supersolar metal abundances and the Broad Line Region of Narrow-line Seyfert 1 galaxies (2001)

MR 2251-178 was the first quasar initially discovered in X-rays, and the first one found to host a warm absorber. Despite its many outstanding multi-wavelength properties, MR 2251-178 has not yet...

Komossa, Stefanie, Mathur, Smita

Narrow-line Seyfert 1 galaxies (NLSy1) are intriguing due to their extreme continuum and emission line properties which are not yet well understood. This paper is motivated by the recent suggestion...

A two-phase model for the Narrow Line Region of NGC 4151 (2001)

The X-ray view of the quasar MR2251-178 and its host cluster: variability, absorption, and intracluster gas emission (2001)

NGC 4151 is one of the brightest and best-studied Seyfert galaxies. Here, we present a two-phase model of the narrow-line region (NLR) of NGC 4151. This study is motivated by (i) the fact that the...

X-rays from the environment of supermassive black holes in active galaxies (2001)

(abridged) MR2251-178 was the first quasar initially discovered in X-rays, and the first one found to host a warm absorber. The quasar turned out to be an outstanding object in many respects. It has...

An optical and X-ray study of the peculiar narrow-line quasar QSO 0117-2837 (2000)

X-rays are a powerful probe of the physical conditions in the nuclei of active galaxies. We review the X-ray properties of radio-quiet AGN, LINERs and ultraluminous IR galaxies based on observations...

Komossa, Stefanie, Grupe, D., Burwitz, V., Janek, M.

We present an optical and X-ray study of the quasar QSO 0117-2837. It exhibits an interesting combination of optical and X-ray properties: Despite its extremely steep observed X-ray spectrum (Gamma_x...

RXTE observation of NGC 6240: a search for the obscured active nucleus (2000)

Ikebe, Yasushi, Leighly, Karen, Tanaka, Yasuo, Nakagawa, Takao, Terashima, Yuichi, Komossa, Stefanie

The wide-band energy spectrum of NGC6240 over the range 0.5-200keV is investigated using the RXTE and ASCA data. The RXTE data provide the spectrum beyond the ASCA range (0.5-10 keV) with significant...

Warm Absorbers in Active Galactic Nuclei (2000)

The giant X-ray outbursts from nearby, non-active galaxies: tidal disruption flares ? (2000)

We first provide a review of the properties of warm absorbers concentrating on what we have learned from ROSAT and ASCA. This includes dusty and dust-free warm absorbers, non-X-ray emission and...

X-ray emission/absorption mechanisms of 4 NLSy-1-like AGN and a radio quasar: QSO 0117-2837, RXJ0134.3-4258, NGC 4051, Mrk 1298, and 4C +74.26 (1999)

One efficient method to probe the direct vicinity of SMBHs in nearby galaxies is to make use of the detection of flares from tidally disrupted stars (e.g., Lidskii & Ozernoi 1979, Rees 1988). The...

Komossa, Stefanie, Meerschweinchen, Janek

We present a study of the X-ray variability properties and spectral shapes of five active galaxies all of which show extreme or enigmatic X-ray properties. We focus on QSO 0117-2837, RXJ0134.3-4258,...

Discovery of a giant and luminous X-ray outburst from the optically inactive galaxy pair RXJ1242.6-1119 (1999)

Komossa, Stefanie, Greiner, Jochen

We report the discovery of large-amplitude X-ray variability from the direction of the previously unknown, optically inactive galaxy pair RXJ1242.6-1119. The X-ray source shows variability by a...

Galactic Fountains and Galactic Winds (1999)

Breitschwerdt, Dieter, Komossa, Stefanie

The development of galactic fountain theories is reviewed with special emphasis on the different approaches and concepts that have been used in the past. In particular the outstanding contribution of...

Testing Narrow-line Seyfert 1 scenarios with photoionization models (1999)

Komossa, Stefanie, Meerschweinchen, Janek

Narrow Line Seyfert 1 (NLSy1) galaxies have recently received a lot of attention due to their unusual optical--X-ray properties which are not yet well understood. Photoionization models of the...

The Steep Spectrum Quasar PG1404+226 with ASCA, HST and ROSAT (1999)

Ulrich, Marie-Helene, Comastri, Andrea, Komossa, Stefanie, Crane, Phil

(abridged) We present and discuss our observations of the NL quasar PG1404+226 with ASCA and HST, and a re-analysis of our earlier observations with ROSAT. The soft X-ray spectrum is very steep and...

X-ray properties of LINERs (1999)

Komossa, Stefanie, Boehringer, Hans, Huchra, John P.

We present an investigation of the X-ray properties of 13 LINERs based on ROSAT all-sky survey and pointed PSPC and HRI observations. Several sources are studied for the first time in X-rays. The...

X-ray emission mechanisms of LINERs (1999)

Komossa, Stefanie, Breitschwerdt, Dieter, Boehringer, Hans, Meerschweinchen, Janek

We present here an analysis of the X-ray properties of a sample of LINER galaxies observed with the ROSAT PSPC and HRI instruments. A spatial analysis shows that the bulk of the X-ray emission is...

Dusty warm absorbers: The case of IRAS 13349+2438 (1999)

Komossa, Stefanie, Breitschwerdt, Dieter, Meerschweinchen, Janek

Warm absorbers are an important new probe of the central region of active galaxies (AGN). Observing and modeling this component provides a wealth of information on the nature of the warm absorber...

The exceptional X-ray properties of the NLSy1 galaxy RXJ 0134.3-4258 (1999)

Komossa, Stefanie, Breitschwerdt, Dieter, Greiner, Jochen, Meerschweinchen, Janek

The Narrow-line Seyfert 1 galaxy RXJ0134.3-4258 was detected during the ROSAT all-sky survey with an ultrasoft spectrum (Greiner 1996). Our later pointed observation led to the discovery of drastic...

Formation of Massive Black Holes in Early Mergers ? (1999)

Schulz, Hartmut, Komossa, Stefanie

We review theoretical and observational arguments favoring a scenario in which a typical massive black hole (MBH) is formed in the merger core of colliding disk systems at high z during the build-up...

The central radio source in the NGC 383 group: jet - IGM interaction ? (1999)

Komossa, Stefanie, Boehringer, Hans

The NGC 383 group is a rich group of galaxies that harbours the central radio source 3C 31 = NGC 383. After presenting results from the X-ray analysis of the extended intra-group medium and the...

The nature of the luminous X-ray emission of NGC 6240 (1999)

X-ray study of the NGC 383 group of galaxies and the source 1E0104+3153 (1999)

We briefly review and extend our discussion of the ROSAT detection of the extraordinarily luminous (> 10^{42} erg/s) partly extended (> 30 kpc diameter) X-ray emission from the ultraluminous infrared...

Komossa, Stefanie, Boehringer, Hans

(abridged) We present results from an analysis of the X-ray properties of the NGC 383 galaxy group based on ROSAT PSPC and HRI data. X-ray emission can be traced out to ~ 1 Mpc, the estimated virial...

The giant X-ray outbursts in NGC 5905 and IC 3599: Follow-up observations and outburst scenarios (1999)

The giant X-ray outburst in NGC 5905 - a tidal disruption event ? (1999)

(abridged) Huge amplitude X-ray outbursts in a few galaxies were reported in the last few years. As one of the exciting possibilities to explain these observations, tidal disruption of a star by a...

The complex X-ray spectra of active galaxies with warm absorbers (1998)

NGC 5905 is one of the very few galaxies that underwent a giant X-ray outburst, with a change in ROSAT photon countrate of a factor ~100. The outburst spectrum is both, very soft and luminous. Our...

The ROSAT view of NGC 1365 and the luminous highly variable off-nuclear X-ray source NGC 1365 - X1 (1998)

Warm absorbers are an important new probe of the central regions of active galaxies. So far, they revealed their existence mainly in the soft X-ray spectral region. In observing and modeling this...

Warm absorbers in Narrow-Line Seyfert 1 galaxies (1998)

We present an X-ray spectral and spatial analysis of the composite starburst/Seyfert galaxy NGC 1365. Excellent fits of the ROSAT PSPC spectrum are obtained by combining a soft thermal component with...

Komossa, Stefanie, Greiner, Jochen

Warm absorbers are an important new tool for investigating the conditions within the central regions of active galaxies. They have been observed in ~50% of the well-studied Seyfert galaxies and have...

The ROSAT view of NGC 1365: core emission, the highly variable source NGC 1365--X1 and alignments of surrounding X-ray sources (1998)

The ULIRG NGC 6240: Luminous extended X-ray emission and evidence for an AGN (1998)

We present a spectral and spatial analysis of the nuclear and circumnuclear X-ray emission of the prominent southern starburst/Seyfert galaxy NGC 1365. To describe the X-ray spectrum of the core...

Schulz, Hartmut, Komossa, Stefanie, Greiner, Jochen

We briefly review and extend our discussion of the ROSAT detection of the extraordinarily luminous (>10^{42} erg/s) partly extended (> 30 kpc diameter) X-ray emission from the double-nucleus...

The giant-amplitude X-ray outburst in NGC 5905 - a tidal disruption event ? (1998)

Properties of warm absorbers in active galaxies (1998)

NGC 5905 is one of the very few galaxies that underwent a giant X-ray outburst, with a change in photon countrate of a factor 100. The outburst spectrum is both, very soft and luminous (Bade, Komossa...

ROSAT HRI discovery of luminous extended X-ray emission in NGC 6240 (1998)

We present a study of the nature of warm absorbers on the basis of ROSAT X-ray observations and photoionization calculations carried out with the code Cloudy. We focus on `non-standard' warm...

Komossa, Stefanie, Schulz, Hartmut, Greiner, Jochen

We report the detection of luminous extended X-ray emission in NGC 6240 on the basis of ROSAT HRI observations of this ultraluminous IR galaxy. The spatial structure and temporal behavior of the...

Properties of dusty warm absorbers and the case of IRAS 17020+4544 (1998)

ROSAT evidence for AGN and superwind activity in NGC 6240 and NGC 2782 (1997)

We present a study of the properties of dusty warm absorbers and point to some important consequences for the resulting X-ray absorption spectra of AGN. Pronounced effects of the presence of dust in...

Schulz, Hartmut, Komossa, Stefanie, Berghoefer, Thomas W., Boer, Berto

We present ROSAT observations of the starburst galaxy NGC 2782 (HRI plus a weak PSPC frame) and the ultraluminous infrared galaxy NGC 6240 (PSPC). The (0.1-2.4) keV spectra of both objects appear...

Soft X-ray properties of the Seyfert 1.8 galaxy NGC 3786 (1997)

Evidence for a dusty warm absorber in NGC 3227 ? (1997)

An analysis of survey and pointed ROSAT PSPC observations of the Seyfert 1.8 galaxy NGC 3786 has revealed interesting spectral and temporal behaviour. The spectrum is found to show clear signs of...

Interpretation of the emission line spectra of Seyfert 2 galaxies by multi-component photoionization models (1997)

We have analyzed survey and pointed \ros PSPC observations of the Seyfert galaxy NGC 3227. Large amplitude X-ray variability is detected, with a factor $\sim$ 15 change in count rate within about 3...

ROSAT Beobachtungen warmer Absorber in aktiven Galaxien [microform] / (1997)

We present multi-component photoionization models allowing for local density inhomogeneities in the NLR to interpret the emission line spectra of Seyfert 2 galaxies. This approach leads to a...

Komossa, Stefanie.

München, Universiẗat, Diss., 1998.

ROSAT observations of warm absorbers in AGN (1996)

A ROSAT observation of the warm-absorbed soft X-ray spectrum of NGC 4051 (1996)

We study the properties of warm absorbers in several active galaxies (AGN) and present new candidates, using ROSAT X-ray observations. Several aspects of the characteristics of warm absorbers are...