The X-ray view of the quasar MR 2251-178 and its host cluster: Variability, absorption, and intracluster gas emission

Komossa, Stefanie

doi:10.1051/0004-6361:20010022

Cited by 3 publications

(7 citation statements)

References 31 publications

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“…MR 2251−178 is surrounded by a giant emission-line nebula of ∼ 10 − 200 kpc extent (e.g., Bergeron et al 1983;Macchetto et al 1990). Bergeron et al (1983) (see also Sect 6.1 of Komossa 2001, for further motivation). We begin our fitting procedure by searching for, and placing constraints on, any cold material along our line-of-sight to the quasar which is in excess to the Galactic absorption toward MR 2251−178.…”

Section: Spectral Modelsmentioning

confidence: 98%

“…If we fix the column density to the Galactic value and re-fit, we obtain a slight change in the value of the photon index to Γ x ∼ 1.9 and the fit gets worse with a change in ∆χ 2 ∼ 140. Taking the upper limit of the extra cold material reported by Komossa (2001) of ∆N H ≡ 5×10 19 cm −2 and including it in the column of gas, we obtain a photon index slightly steeper and the fit gets worse if we increase the column density of the extra cold material by one and two times ∆N H (see rows 3 and 4 in Table 2), increasing χ 2 (respect with N H free to vary) by ∆χ 2 = 260 and 396 respectively.…”

Section: Spectral Modelsmentioning

confidence: 99%

“…Now, let us consider the absorption features at ≈ 18 Å and ≈ 15 Å in turn. Komossa (2001) fitted a power-law with two edges at the theoretical positions of O vii and O viii, 739 eV and 871 eV respectively, representing the warm absorber, obtaining τ O VII = 0.22 ± 0.11 and τ O VIII = 0.24 ± 0.12. The high sensitivity and resolution of the Chandra LETG spectrometer coupled with the good quality of the observation of MR 2251−178, allow us to fit these features with a high precision.…”

Section: Spectral Modelsmentioning

confidence: 99%

“…Several studies have been focused on the characterization of the absorbing material properties. Komossa (2001) fitted a warm absorber model to the ROSAT observation of MR 2251−178, and found a high ionization state of the absorber (log U ∼ 0.5), and a column density of N H ∼ 10 22.6 cm −2 . Monier et al (2001) reported the presence of absorption lines of N v λ1240 and C iv λ1549 blueshifted by few hundreds of km s −1 .…”

mentioning

confidence: 99%

“…For the first time, we search for the presence of a dusty warm absorber in MR 2251−178. Based on ROSAT data, Komossa (2001) speculated about the presence of a second dusty warm absorber in MR 2251−178, this second warm absorber dusty, but the data did not allow multi-component fitting, which would provide important implications on the global structure of MR 2251−178.…”

mentioning

confidence: 99%

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ChandraLETGS Spectroscopy of the Quasar MR 2251−178 and Its Warm Absorber

Ramírez

Komossa

Burwitz

et al. 2008

ApJ

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We present an analysis of our Chandra Low Energy Transmission Grating Spectrometer (LETGS) observation of the quasar MR 2251−178. The warm absorber of MR 2251−178 is well described by a hydrogen column density, N H ≈ 2 × 10 21 cm −2 , and an ionization parameter log(ξ) ≈ 0.6. We find in the spectrum weak evidence for narrow absorption lines from Carbon and Nitrogen which indicate that the ionized material is in outflow. We note changes (in time) of the absorption structure in the band (0.6 − 1) keV (around the UTAs plus the O vii and O viii K-edges) at different periods of the observation. We measure a (0.1 − 2) keV flux of 2.58 ×10 −11 ergs cm −2 s −1 . This flux implies that the nuclear source of MR 2251−178 is in a relatively low state. No significant variability is seen in the light curve. We do not find evidence for an extra cold material in the line of sight, and set an upper limit of N H ≈ 1.2 × 10 20 cm −2 . The X-ray spectrum does not appear to show evidence for dusty material, though an upper limit in the neutral carbon and oxygen column densities can only be set to N C I ≈ 2 × 10 19 cm −2 and N O I ≈ 9 × 10 19 cm −2 , respectively.

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Section: Spectral Modelsmentioning

confidence: 98%

Section: Spectral Modelsmentioning

confidence: 99%

Section: Spectral Modelsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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ChandraLETGS Spectroscopy of the Quasar MR 2251−178 and Its Warm Absorber

Ramírez

Komossa

Burwitz

et al. 2008

ApJ

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A Search for Very Extended Ionized Gas in Nearby Starburst and Active Galaxies

Veilleux¹,

Shopbell²,

Rupke³

et al. 2003

Astron J

102

146

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We report the results from a pilot study of 10 nearby starburst and active galaxies conducted with the Taurus Tunable Filter (TTF) on the Anglo-Australian and William Herschel Telescopes. The main purpose of this imaging survey is to search for warm emission-line gas on the outskirts (galactocentric distances R 10 kpc) of galaxies to provide direct constraints on the size and geometry of the "zone of influence" of these galaxies on their environment. Gaseous complexes or filaments larger than ∼ 20 kpc are discovered or confirmed in six of the galaxies in the sample (NGC 1068, NGC 1482, NGC 4388, NGC 6240, NGC 7213, and MR 2251. Slightly smaller structures are seen for the first time in the ionization cones and galactic winds of NGC 1365, NGC 1705, Circinus galaxy, and ESO484-G036. The TTF data are combined with new optical long-slit spectra as well as published and archived radio and X-ray maps to constrain the origin and source of ionization of these filaments. A broad range of phenomena is observed, including large-scale ionization cones and galactic winds, tidal interaction, and ram-pressure stripping by an intracluster medium. The source of ionization in this gas ranges from shock ionization to photoionization by the central AGN or in-situ hot young stars. The sample is too small to draw statistically meaningful conclusions about the extent and properties of the warm ionized medium on large scale and its relevance to galaxy formation and evolution. The next generation of tunable filters on large telescopes promises to improve the sensitivity to faint emission-line fluxes at least tenfold and allow systematic surveys of a large sample of emission-line galaxies.

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The Properties and Evolution of the Highly Ionized Gas in MR 2251−178

Kaspi

Netzer

Chelouche

et al. 2004

ApJ

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We present the first XMM-Newton observations of the radio-quiet quasar MR 2251À178 obtained in 2000 and 2002. The EPIC pn spectra show a power-law continuum with a slope of À ¼ 1:6 at high energies absorbed by at least two warm absorbers (WAs) intrinsic to the source. The underlying continuum in the earlier observation shows a ''soft excess'' at low X-ray energies, which can be modeled as an additional power law with À ¼ 2:9. The spectra also show a weak narrow iron K emission line. The high-resolution grating spectrum obtained in 2002 shows emission lines from N vi, O vii, O viii, Ne ix, and Ne x, as well as absorption lines from the lowionization ions of O iii, O iv, and O v, and other confirmed and suspected weaker absorption lines. The O iii-O v lines are consistent with the properties of the emission-line gas observed as extended optical [O iii] emission in this source.The signal-to-noise ratio of the 2000 grating data is too low to detect any lines. We suggest a model for the high-resolution spectrum that consists of two or three WA components. The two-component model has a high-ionization WA with a column density of 10 21.5 -10 21.8 cm À2 and a low-ionization absorber with a column density of 10 20.3 cm À2 . In the three-component model we add a lower ionization component that produces the observed iron M shell absorption lines. We investigate the spectral variations in MR 2251À178 over a period of 8.5 yr using data from ASCA, BeppoSAX, and XMM-Newton. All X-ray observations can be fitted with the above two power laws and the two absorbers. The observed luminosity variations seem to correlate with variations in the soft X-ray continuum. The 8.5 yr history of the source suggests a changing X-ray absorber due to material that enters and disappears from the line of sight on timescales of several months. We also present, for the first time, the entire Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of MR 2251À178. We detect emission from N iii, C iii, and O vi and at least four absorption systems in C iii, H i, and O vi, one at À580 km s À1 and at least three others that are blended together and form a wide trough covering the velocity range of 0 to À500 km s À1 . The general characteristics of the UV and X-ray absorbers are consistent with an origin in the same gas.

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The X-ray view of the quasar MR 2251-178 and its host cluster: Variability, absorption, and intracluster gas emission

Cited by 3 publications

References 31 publications

ChandraLETGS Spectroscopy of the Quasar MR 2251−178 and Its Warm Absorber

ChandraLETGS Spectroscopy of the Quasar MR 2251−178 and Its Warm Absorber

A Search for Very Extended Ionized Gas in Nearby Starburst and Active Galaxies

The Properties and Evolution of the Highly Ionized Gas in MR 2251−178

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