Multiwavelength campaign on Mrk 509

Abstract

We present medium-resolution (λ/Δλ ∼ 20 000) ultraviolet spectra covering the 1155−1760 Å spectral range of the Seyfert 1 galaxy Mrk 509 obtained using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). Our observations were obtained simultaneously with a Low Energy Transmission Grating Spectrometer observation using the Chandra X-ray Observatory, and they are part of a multiwavelength campaign in September through December 2009 which also included observations with XMM-Newton, Swift, and INTEGRAL. Our spectra are the highest signal-to-noise observations to date of the intrinsic absorption components seen in numerous prior ultraviolet observations. To take advantage of the high S/N, we describe special calibrations for wavelength, flat-field and line-spread function corrections that we applied to the COS data. We detect additional complexity in the absorption troughs compared to prior observations made with the Space Telescope Imaging Spectrograph (STIS) on HST. We attribute the UV absorption to a variety of sources in Mrk 509, including an outflow from the active nucleus, the interstellar medium and halo of the host galaxy, and possible infalling clouds or stripped gaseous material from a merger that are illuminated by the ionizing radiation of the active nucleus. Variability between the STIS and COS observation of the most blue-shifted component (#1) allows us to set an upper limit on its distance of <250 pc. Similarly, variability of component 6 between FUSE observations limits its distance to <1.5 kpc. The absorption lines in all components only partially cover the emission from the active nucleus with covering fractions that are lower than those seen in the prior STIS observations and are comparable to those seen in spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE). Given the larger apertures of COS and FUSE compared to STIS, we favor scattered light from an extended region near the active nucleus as the explanation for the partial covering. As observed in prior X-ray and UV spectra, the UV absorption has velocities comparable to the X-ray absorption, but the bulk of the ultraviolet absorption is in a lower ionization state with lower total column density than the gas responsible for the X-ray absorption. We conclude that the outflow from the active nucleus is a multiphase wind.

Multiwavelength campaign on Mrk 509

“…The absorption component with the highest redshift relative to the systemic velocity is only observed in the UV and is likely to be a high velocity cloud near the host galaxy . From studying the absorption troughs either at rest or outflowing in the UV, it appears that these are clustered around −300 and +16 km s −1 (Kriss et al 2000;Kraemer et al 2003;Kriss et al 2011). Fitting model 2, Detmers et al (2011) finds outflow velocities of −13 ± 11 km s −1 and −319 ± 14 km s −1 , consistent with the main absorption troughs detected in the UV.…”

“…The uncertainty in the mass of the black hole obtained from reverberation mapping is about 30% (Peterson et al 2004), and is higher for the mass of the whole galaxy owing to the spread in the Magorrian relation as well as our assumption that there is only a bulge in this clearly disturbed galaxy (see Fig. 8 of Kriss et al 2011). However, the metallicity determination is only slightly affected by assuming masses of only 2 × 10 10 or 8 × 10 10 M .…”

Multiwavelength campaign on Mrk 509

“…If we would assume that this emission stems from an X-ray broad line region, and that there should be a similar blue wing, then the absence of such a blue wing in the observed spectrum might be explained by absorption. Partial absorption of the blue wing due to an outflow is also seen in the Lyα line of hydrogen, for example Kriss et al (2011). However that absorption extends only up to −500 km s −1 in the UV spectrum.…”

Discovery of a fast, broad, transient outflow in NGC 985

“…All observations used multiple central wavelength settings and focal-plane positions (FP-POS) to allow our merged spectra to span the gaps between the two detector segments and eliminate flat-field features and detector defects. The individual exposures were combined with updated wavelength calibrations, flat-field procedures, and flux calibrations as described by Kriss et al (2011) andDe Rosa et al (2015). The wavelength zero point was adjusted by matching the low-ionization interstellar absorption features in the spectrum to the H i velocity of v LSR = −7 km s −1 (Wakker et al 2011).…”