X-ray spectroscopy of NGC 5548

Kaastra, J. S.; Steenbrugge, K. C.; Raassen, A. J. J.; Meer, R. L. J. van der; Brinkman, A. C.; Liedahl, D. A.; Behar, E.; Rosa, A. De

doi:10.1051/0004-6361:20020235

Cited by 158 publications

(263 citation statements)

References 31 publications

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“…From a dynamical modeling of the BLR (Pancoast et al 2014), it is inferred that this source is observed at an inclination angle of ∼30 • and hosts a supermassive black hole (SMBH) of ∼3 × 10 7 M in its center. Previously, high resolution UV (Crenshaw & Kraemer 1999;Crenshaw et al 2003a) and X-ray (Kaastra et al , 2002Steenbrugge et al 2003Steenbrugge et al , 2005) spectra have revealed several deep NAL that can be ascribed to a moderate velocity (v out = 200−1200 km s −1 ) ionized outflow.…”

Section: Introductionmentioning

confidence: 99%

Anatomy of the AGN in NGC 5548

Gesu

Costantini

Ebrero

et al. 2015

A&A

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During an extensive multiwavelength campaign that we performed in 2013−2014, we found the prototypical Seyfert 1 galaxy NGC 5548 in an unusual condition of heavy and persistent obscuration. The newly discovered "obscurer" absorbs most of the soft X-ray continuum along our line of sight and lowers the ionizing luminosity received by the classical warm absorber. We present the analysis of the high resolution X-ray spectra collected with XMM-Newton and Chandra throughout the campaign, which are suitable to investigate the variability of both the obscurer and classical warm absorber. The time separation between these X-ray observations range from two days to eight months. On these timescales the obscurer is variable both in column density and in covering fraction. This is consistent with the picture of a patchy wind. The most significant variation occurred in September 2013 when the source brightened for two weeks. A higher and steeper intrinsic continuum and a lower obscurer covering fraction are both required to explain the spectral shape during the flare. We suggest that a geometrical change of the soft X-ray source behind the obscurer causes the observed drop in the covering fraction. Because of the higher soft X-ray continuum level, the September 2013 Chandra spectrum is the only X ray spectrum of the campaign in which individual features of the warm absorber could be detected. The spectrum shows absorption from Fe-UTA, O , and O , consistent with belonging to the lower-ionization counterpart of the historical NGC 5548 warm absorber.Hence, we confirm that the warm absorber has responded to the drop in the ionizing luminosity caused by the obscurer.

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Section: Introductionmentioning

confidence: 99%

Anatomy of the AGN in NGC 5548

Gesu

Costantini

Ebrero

et al. 2015

A&A

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“…In general, the continuum is well described by a power-law component and a soft excess. In about 50% of Seyfert 1 galaxies , narrow absorption lines from highly ionised gas are observed, with the gas generally outflowing at a velocity of between 100 and a few 1000 km s −1 (Kaastra et al 2002). This absorption can be studied in detail in the UV and X-ray part of the spectrum.…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength campaign on Mrk 509

Steenbrugge

Kaastra

Detmers

et al. 2011

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Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of the abundance by comparing local and higher redshift galaxies. However, the methods used so far have substantial drawbacks or rather large uncertainties. Some of the measurements are at odds with the initial mass function derived from the older stellar population of local elliptical galaxies. Aims. We determine accurate and reliable abundances of C, N, Ne, and Fe relative to O from the narrow absorption lines observed in the X-ray spectra of Mrk 509. Methods. We use the stacked 600 ks XMM-Newton RGS and 180 ks Chandra LETGS spectra. Thanks to simultaneous observations with INTEGRAL and the optical monitor on-board XMM-Newton for the RGS observations and HST-COS and Swift for the LETGS observations, we have an individual spectral energy distribution for each dataset. Owing to the excellent quality of the RGS spectrum, the ionisation structure of the absorbing gas is well constrained, allowing for a reliable abundance determination using ions over the whole observed range of ionisation parameters. Results. We find that the relative abundances are consistent with the proto-solar abundance ratios: C/O = 1.19 ± 0.08, N/O = 0.98 ± 0.08, Ne/O = 1.11 ± 0.10, Mg/O = 0.68 ± 0.16, Si/O = 1.3 ± 0.6, Ca/O = 0.89 ± 0.25, and Fe/O = 0.85 ± 0.06, with the exception of S, which is slightly under-abundant, S/O = 0.57 ± 0.14. Our results, and their implications, are discussed and compared to the results obtained using other techniques to derive abundances in galaxies.

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“…Photoionization modeling has then shown that, in many cases, more than one ionization parameter 1 is needed to describe the observed spectrum (e.g, Morales et al 2000;Kaspi et al 2001;Kaastra et al 2002). Also, the positions of the lines point toward outflow velocities on the order of a few hundred to a few thousand km s −1 .…”

Section: Introductionmentioning

confidence: 99%

On the location and composition of the dust in the MCG–6-30-15 warm absorber

Ballantyne¹,

Weingartner²,

Murray³

2003

A&A

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Abstract. The warm absorber observed in the Seyfert 1 galaxy MCG-6-30-15 is known to consist of at least two zones and very likely contains dust. Hubble Space Telescope images of MCG-6-30-15 show a dust lane crossing the galaxy just below the nucleus. In this paper, we argue that this dust lane is responsible for the observed reddening of the nuclear emission and the Fe  edge hinted at in the Chandra spectrum of MCG-6-30-15. We further suggest that the gas within the dust lane can comprise much of the low ionization component (i.e., the one contributing the O  edge) of the observed warm absorber. Moreover, placing the warm absorbing material at such distances (hundreds of pc) can account for the small outflow velocities of the low ionization absorption lines as well as the constancy of the O  edge. Photoionization models of a dusty interstellar gas cloud (with a column appropriate for the reddening toward MCG-6-30-15) using a toy Seyfert 1 spectral energy distribution show that it is possible to obtain a significant O  edge (τ ∼ 0.2) if the material is ∼150 pc from the ionizing source. For MCG-6-30-15, such a distance is consistent with the observed dust lane. We emphasize the point first made by Kraemer et al.: dusty interstellar material will likely contribute to the warm absorber, and should be included in spectral modeling. The current data on MCG-6-30-15 is unable to constrain the dust composition within the warm absorber. Astronomical silicate is a viable candidate, but there are indications of a very low O abundance in the dust, which is inconsistent with a silicate origin. If true, this may indicate that there were repeated cycles of grain destruction and growth from shocks in the interstellar medium of MCG-6-30-15. Pure iron grains are an unlikely dust constituent due to the limit on their abundance in the Galaxy, yet they cannot be ruled out. The high column densities inferred from the highly ionized zone of the warm absorber implies that this gas is dust-free.

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X-ray spectroscopy of NGC 5548

Cited by 158 publications

References 31 publications

Anatomy of the AGN in NGC 5548

Anatomy of the AGN in NGC 5548

Multiwavelength campaign on Mrk 509

On the location and composition of the dust in the MCG–6-30-15 warm absorber

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