Shadowing of the 0.25-keV extragalactic X-ray background by the disc of NGC 55

Barber, C. R.; Roberts, T. P.; Warwick, R. S.

doi:10.1093/mnras/282.1.157

Cited by 35 publications

(26 citation statements)

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“…Their results, which are based on new Chandra X-ray observations of the source, are consistent with the tidal tail being located in front of the soft X-ray nebula in our line of sight, such that the soft X-ray emission is partially absorbed by the cold gas in the tidal tail. Moreover, Iwasawa et al (2011) derived a lower limit on the column density of N H ∼ 10 22 cm −2 , which is similar to that of edge-on galaxy disks and consistent with other measurements of disk shadowing (Barber et al 1996). Iwasawa et al (2011) concluded that the source of the soft X-ray emitting gas is likely to be star formation in the edge-on disk, which would be, a priori, consistent with our INT/WFC image.…”

Section: Int Imaging: Low Surface Brightness Emission At Large Scalessupporting

confidence: 87%

Extended warm gas in the ULIRG Mrk273: Galactic outflows and tidal debris

Zaurín

Tadhunter

Rupke

et al. 2014

A&A

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We present new HST/ACS medium-and narrow-band images and optical Isaac Newton Telescope long-slit spectra of the merging system Mrk273. The HST observations sample the [OIII]λλ4959,5007 emission from the galaxy and the nearby continuum. These data were taken as a part of a larger study of ultraluminous infrared galaxies (ULIRGs) with the aim of investigating the importance of the warm, AGN induced outflows in such objects. The HST images show that the morphologies of the extended continuum and the ionised gas emission from the galaxy are decoupled, extending almost perpendicular to each other. In particular, we detect for the first time a spectacular structure of ionised gas in the form of filaments and clumps that extend ∼23 kpc to the east of the nuclear region. The quiescent ionised gas kinematics at these locations suggests that these filaments are tidal debris left over from a secondary merger event that are illuminated by an AGN in the nuclear regions. The images also reveal a complex morphology in the nuclear region of the galaxy for both the continuum and the [OIII] emission. Consistent with this complexity, we find a wide diversity of emission line profiles in these regions. Kinematic disturbance in the form of broad (FWHM > 500 km s −1 ) and/or strongly shifted (|∆V| > 150 km s −1 ) emission line components is found at almost all locations in the nuclear regions, but confined to a radius of ∼4 kpc to the east and west of the northern nucleus. In most cases, we are able to fit the profiles of all the emission lines of different ionisation with a kinematic model using two or three Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionisation mechanisms at the different locations in the galaxy. We show that these line ratios are generally consistent with photoionisation by an AGN as the main ionisation mechanism. Finally, the highest surface brightness [OIII] emission is found in a compact region that is coincident with the so-called SE nuclear component. The compactness, kinematics, and emission line ratios of this component suggest that it is a separate nucleus with its own AGN. At this stage, further observations are required to confirm the dual (or multiple?) AGN nature of Mrk273.

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Section: Int Imaging: Low Surface Brightness Emission At Large Scalessupporting

confidence: 87%

Extended warm gas in the ULIRG Mrk273: Galactic outflows and tidal debris

Zaurín

Tadhunter

Rupke

et al. 2014

A&A

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“…which is fully consistent with Barber et al (1996) within the uncertainties. After seven iteration steps no further improvement can be achieved.…”

Section: Testing the Two Dimensional Correlationsupporting

confidence: 88%

“…We assume an average spectral index of Γ = 1.5 according to Hasinger et al (2001). Its ROSAT C-band intensity was determined by Barber et al (1996); they derived I EXTRA = 228 × 10 −6 cts s −1 arcmin −2 with an uncertainty of 90 × 10 −6 cts s −1 arcmin −2 . Throughout the fit procedure (see Sect.…”

Section: The Extragalactic Componentmentioning

confidence: 99%

The composition of the interstellar medium towards the Lockman Hole

Kappes¹,

Kerp²,

Richter³

2003

A&A

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Abstract. The Lockman Hole is well known as the region with the lowest neutral atomic hydrogen column density on the entire sky. We present an analysis of the soft X-ray background radiation towards the Lockman Hole using ROSAT all-sky survey data. This data is correlated with the Leiden/Dwingeloo survey (Galactic H  21 cm-line emission) in order to model the soft X-ray background by using radiative transfer calculations for four ROSAT energy bands simultaneously. It turns out, that an important gas fraction, ranging between 20-50%, of the X-ray absorbing material is not entirely traced by the H  but is in the form of ionized hydrogen. Far-ultraviolet absorption line measurements by FUSE are consistent with this finding and support an ionized hydrogen component towards the Lockman Hole.

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“…We used the extremely simple approach that the 1/4 keV intensity across the entire field of interest is constant for all three SXRB source components. The derived intensities are -fiocai = 4.4-10 -6 ctss -1 arcmin -2 , /halo = 16-10 -6 ctss -1 arcmin -2 and / e x t r a = 2.3-10 -6 ctss _ 1 arcmin -2 (Barber et al 1996) and constant across the field of interest. The Galactic X-ray halo is the brightest X-ray source of all.…”

Section: T H E Soft X-ray Backgroundmentioning

confidence: 89%

“…If we sum the X-ray absorption of the WNM and the HVC filament we expect to detect a ~ 26% intensity variation in the ROSAT 3/4keV data. The HVC may be so distant (Wakker & van Woerden 1997) that its column density distribution only attenuates the extragalactic background radiation with an intensity of /extra(3/4 keV) ~ 0.53 • 1 0 -4 c t s s -1 arcmin -2 (Barber et al 1996). This gives a 3/4keV intensity attenuation of AT e xtra(WNM + HVC) = 0.10 • 10~4 cts s-1 arcmin -2 which is extremely difficult to detect significantly, even in deep pointed PSPC observations.…”

Section: ° 'Kmentioning

confidence: 99%

High-Velocity Clouds and their Soft X-ray Emission

Kerp

Pietz

Kalberla

et al. 1997

International Astronomical Union Colloquium

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Abstract. Diffuse excess 1/4 keV soft X-ray emission was found to be positionally correlated with the column density distribution of the high velocity cloud (HVC) complex C (Kerp et al. 1996). Here we point out that the detected diffuse X-ray emission is indeed associated with the HVC phenomenon. For this purpose we study the 1/4 keV radiation transfer as well as the Hi column density distribution of HVCs and intermediate velocity clouds (IVCs) towards HVC complex C in detail. We present evidence that on arcmin scales the 3/4 keV soft X-ray emission is positionally anticorrelated with the HVC column density distribution of an individual HVC filament of complex C. IntroductionUp to now HVCs have been detected, in emission, only in the line radiation of the neutral atomic hydrogen (for a comprehensive review see Wakker & van Woerden 1997). Recent analyses of ROSAT data, suggest that HVCs also emit soft X-rays (Herbstmeier et al. 1995and Kerp et al. 1994, 1995, 1996. Here we focus on HVC complex C towards high galactic latitudes. We present a comparative analysis of X-ray and HI 21 cm line data available in this region (73° < I < 118°, 38° < b < 63°). In the l/4keV energy regime one has to disentangle the X-ray emission of the individual soft X-ray sources which contribute to the observed X-ray background in order to reveal the excess emission associated with the HVCs. Especially the intermediate-and low-velocity gas determines the intensity distribution of the soft X-ray sky, by photoelectric absorption. Because of the much smaller absorption cross section in the 3/4 keV band such a decomposition is not necessary. We will demonstrate that it is feasible to separate the emission of the "normal" soft X-ray background (SXRB) from that of the excess emission associated with HVCs. In consequence we have to solve the radiation transport of soft X-ray photons through the galactic interstellar medium (ISM) to identify sky areas which reveal deviations from this "normal" SXRB intensity distribution. Here we focus on two aspects which are important to understanding the recent results on X-ray emission of HVCs. First, we will show that the ROSAT 1/4 keV all-sky survey data reveal soft X-ray emission which is positionally correlated with the HVCs of complex C. We show new H121 cm line maps of the total and IVC column density distribution and discuss the relation of the individual cloud populations to the appearance of the soft X-ray intensity distribution on the sky. Second, we will discuss in Sect. 3 the small scale positional association of an individual HVC filament with excess soft X-ray emission in the ROSAT 3/4keV energy band. This is of importance because the 3/4 keV radiation can penetrate the galactic ISM without significant attenuation towards high galactic latitudes. T h e Soft X-ray BackgroundIt is a matter of discussion whether the SXRB has a patchy source intensity distribution or not (see also Pietz et al., Snowden, and Wang; this volume). For our purpose knowledge of the soft X-ray intensity distribution on ...

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Shadowing of the 0.25-keV extragalactic X-ray background by the disc of NGC 55

Cited by 35 publications

References 0 publications

Extended warm gas in the ULIRG Mrk273: Galactic outflows and tidal debris

Extended warm gas in the ULIRG Mrk273: Galactic outflows and tidal debris

The composition of the interstellar medium towards the Lockman Hole

High-Velocity Clouds and their Soft X-ray Emission

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