Surprises from a Deep [ITAL]ASCA[/ITAL] Spectrum of the Broad Absorption Line Quasar PHL 5200 (original) (raw)

Strong X-ray Absorption in a BALQSO: PHL5200

Arxiv preprint astro-ph/9510009, 1995

We present ASCA observations of the z=1.98 prototype BALQSO: PHL5200. The source was detected in both SIS and GIS. A power-law spectrum (E = 0:6 +0:9 0:6) with large intrinsic absorption (N H = 1:3 +2:3 1:1 10 23 cm 2) best describes the spectrum. Excess column density over the local Galactic value is required at the 99% con dence level. This detection suggests that, although BALQSOs are X-ray quiet, it is strong absorption in the BAL region that makes them appear faint to low energy X-ray experiments. The required intrinsic absorbing column density is two to three orders of magnitude larger than earlier estimates of column densities in BALQSOs. This implies that the BAL systems are much more highly ionized than previously thought.

Strong X-Ray Absorption in a Broad Absorption Line Quasar: PHL 5200

The Astrophysical Journal, 1995

We present ASCA observations of the z ϭ 1.98 prototype broad absorption line quasar (BALQSO): PHL 5200. The source was detected in both SIS and GIS. A power-law spectrum (␣ E ϭ 0.6 Ϫ0.6 ϩ0.9) with large intrinsic absorption (N H ϭ 1.3 Ϫ1.1 ϩ2.3 ϫ 10 23 cm Ϫ2) best describes the spectrum. Excess column density over the local Galactic value is required at the 99% confidence level. This detection suggests that, although BALQSOs are X-ray-quiet, it is strong absorption in the BAL region that makes them appear faint to low-energy X-ray experiments. The required intrinsic absorbing column density is 2-3 orders of magnitude larger than earlier estimates of column densities in BALQSOs. This implies that the BAL systems are much more highly ionized than was previously thought.

Evidence Against BALS in the X-ray Bright QSO PG1416-129

Eprint Arxiv Astro Ph 9702207, 1997

Recent results from the ROSAT All Sky Survey, and from deep ROSAT pointings reveal that broad absorption line quasars (BALQSOs) are weak in the soft X-ray bandpass (with optical-to-X-ray spectral slope alpha_{ox}>1.8) in comparison to QSOs with normal OUV spectra (mean alpha_{ox}=1.4). One glaring exception appeared to be the nearby BALQSO PG1416-129, which is a bright ROSAT source showing no evidence for intrinsic soft X-ray absorption. We present here our new HST FOS spectrum of PG1416-129, in which we find no evidence for BALs. We show that the features resulting in the original BAL classification, based on IUE spectra, were probably spurious. On the basis of UV, X-ray and optical evidence, we conclude that PG1416-129, is not now, and has never been a BALQSO. Our result suggests that weak soft X-ray emission is a defining characteristic of true BALQSOs. If BALQSOs indeed harbor normal intrinsic spectral energy distributions, their observed soft X-ray weakness is most likely the result of absorption. The ubiquitous occurrence of weak soft X-ray emission with UV absorption (BALs) thus suggests absorbers in each energy regime that are physically associated, if not identical.

The Unusual Spectral Energy Distribution of LBQS 0102-2713

The Astrophysical Journal, 2009

We have studied the spectral energy distribution of the quasar LBQS 0102-2713. The available multiwavelength data in the observers frame are one optical spectrum between 3200 and 7400 Å, seven Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra between 1700 and 2300 Å, one GALEX NUV flux density and a K S magnitude obtained from NASA/IPAC Extragalactic Database, and three public ROSAT PSPC pointed observations in the 0.1-2.4 keV energy band. The α ox values obtained from the HST FOS, the optical spectrum, and the ROSAT observations are −2.3 and −2.2, respectively, comparable to broad absorption line (BAL) quasars. The 2500 Å luminosity density is about a factor of 10 higher compared to the mean of the most luminous Sloan Digital Sky Survey quasars. The 2 keV νL ν value is lower by about a factor of 10 compared to the radio-loud quasars shown in Figure 10 of Richards et al. LBQS 0102-2713 exhibits one of the steepest soft X-ray photon indices obtained so far. For a simple power-law fit with leaving the N H free in the fit, we obtain a photon index of Γ = 6.0 ± 1.3. Fixing the N H value to the Galactic value, the photon index still remains steep with a value of about 3.5. We argue that LBQS 0102-2713 is similar to BAL quasars with respect to their UV brightness and 2 keV X-ray weakness. However, the absorption by neutral matter is significantly lower compared to BAL quasars. The X-ray weakness is most probably not due intrinsically X-ray weakness based on the UV line strengths which are comparable to the line strength values reported in quasar composites. If the X-ray weakness will be confirmed in future observations, LBQS 0102-2713 might be indicative for a new class of quasars with an unusual combination in their UV, X-ray, and N H properties.

X‐Ray and Ultraviolet Spectral Properties of the X‐Ray Transient Quasar PG 0844+349

The Astrophysical Journal, 2000

Despite the fact that quasars are generally strong X-ray emitters, ROSAT discovered several objects with only very weak X-ray emission. In this paper, the X-ray data from ASCA and ROSAT and the UV spectra from Hubble Space T elescope (HST ) and IUE of one of these quasars, PG 0844]349, are analyzed. The ROSAT spectrum can be well Ðtted by a single power law with Galactic absorption. No spectral variations were observed during changes of the 0.1È2.4 keV X-ray Ñux by a factor of 10 between the ROSAT All-Sky Survey and pointed observations, separated by 6 months. The ASCA satellite found the object in a high state with a photon index of 1.98 and an Fe Ka line with EW D 300 eV. The X-ray Ñux in the 2È10 keV band is highly variable ; the fastest variation detected is 60% in less than 2 ] 104 s. The measured excess variance Ðts well the excess variance versus relation for Seyfert 1 galaxies ; L 2h10keV the Ñux variability in the 0.5È2.0 keV band shows a slightly higher amplitude than in the 2È10 keV band. We show that the optical microvariability of this object can actually be driven by reprocessing of the variable X-ray Ñux if one-half of the absorbed X-rays are reradiated in the optical-to-UV band. A weak broad intrinsic absorption line (FWHM^800 km s~1), most likely Lya absorption blueshifted by a velocity^[6000 km s~1 relative to the quasarÏs rest frame, is found in the HST Faint Object Spectrograph spectrum. A similar C IV broad absorption line may also be present in the low-resolution IUE spectrum. Historic light curves in the X-ray, UV, and optical bands indicate that the variability amplitude in the UV and optical bands is much smaller than in the X-ray band. The QSO can be classiÐed as X-ray weak only on one occasion out of Ðve X-ray observations. An analysis of the long-term behavior of several other X-rayÈweak objects shows no indications of a similar large X-ray variability.

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301

The Astrophysical Journal, 2000

We present a deep ASCA observation of a Broad Absorption Line Quasar (BALQSO) PG0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (N H > ∼ 10 24 cm −2 ) toward PG0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to one, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

The X-ray emission from broad absorption line quasars

1999

PG 1411+442, and PG 0043+039. All three objects are found to be X-ray quiet, possibly due to substantial intrinsic absorption with N-H > 10(23) cm(-2) but might have intrinsically a more typical spectral energy distribution. This picture is supported by explicit spectral fits to the combined ROSAT/ASCA data of the nearby bright object PG 1411+442. An analysis of the large number of radio-quiet quasars not detected in the ROSAT All-Sky Survey indicates that perhaps only a small fraction of BAL quasars have not been recognized before and that the number of intrinsically X-ray quiet quasars must be small.

The Correlation Between X-ray and UV Properties of BAL QSOs

We compile a large sample of broad absorption line (BAL) quasars with X-ray observations from the XMM-Newton archive data and Sloan Digital Sky Survey Data Release 5. The sample consists of 41 BAL QSOs. Among 26 BAL quasars detected in X-ray, spectral analysis is possible for 12 objects. X-ray absorption is detected in all of them. Complementary to that of Gallagher et al., our sample spans wide ranges of both BALnicity index (BI) and maximum outflow velocity (v max ). Combining our sample with that of Gallagher et al., we find very significant correlations between the intrinsic X-ray weakness and both BI and the maximum velocity of the absorption trough. We do not confirm the previously claimed correlation between absorption column density and BAL parameters. Our tentative interpretation is that X-ray absorption is necessary to the production of the BAL outflow, but the properties of the outflow are largely determined by intrinsic spectral energy distribution of the quasars.

X-Ray Study of the Distant QSO PKS 0237-233 with ASCA and ROSAT

Publications of the Astronomical Society of Japan, 1998

The X-ray spectrum of the distant QSO PKS 0237-233 (z = 2.223) has been studied with ASCA and ROSAT. The spectrum in the energy ränge 0.1 keV to 8 keV in the observer's frame is well fitted by a power-law model with a photon index of 1.54 ± 0.06 absorbed by the galactic interstellar matter. The lack of excess absorption confirms that such absorption is not a universal property of the high-redshift GHz-peaked spectrum (GPS) sources. From a comparison of the Lyman a and the metal absorption lines in the optical and UV bands, small amount of X-ray absorption constrains the ionization State of the metal line System at z = 1.65 as [Hl/H] > 2.5 x 10~4 and [Civ/C] > 0.11 if the metal line Systems have a metal abundance of 0.1 Z< §.