260 likes | 386 Views
The First-Known Radio-Loud BAL Quasar PKS 1004+13. Bev Wills (U.Texas) with W.N.Brandt, A.Laor, B.Miller & S. Gallagher. Fifteen to 20 % of luminous quasars show broad absorption line (BAL) troughs indicating outflows up to 0.1c or more. In addition to high-ionizaton absorption
E N D
The First-Known Radio-Loud BAL Quasar PKS 1004+13 Bev Wills (U.Texas) with W.N.Brandt, A.Laor, B.Miller & S. Gallagher
Fifteen to 20% of luminous quasars show broad absorption line (BAL) troughs indicating outflows up to 0.1c or more. In addition to high-ionizaton absorption ~10% of BAL quasars (BALQs) show low ionization absorption troughs, e.g., of AlIII l1860, MgII l2798, etc. PG 0946+301. Thanks to Nahum Arav et al. (1999).
BALQs often show • narrower associated absorption (NALs, ~500 km/s), • often of lower outflow velocity. • polarization ~1-2%, several % in case of loBALQs. • reddening by dust, especially loBALQs. • weak in 0.2-10 keV X-rays, often suppressed by >20, largely the result of absorption. • Historically, BALQs thought always to be radio-quiet • (Radio Loud: ratio of radio (5GHz) to 2500A luminosity > 10).
Two hypotheses, both are operating: • Orientation. Incomplete global covering from X-ray, optical-UV spectropolarimetry, implies a significant fraction of quasars have such outflows away from our line-of-sight. Similarity of emission-line spectra suggest BAL and non-BAL quasars are the same kinds of objects. • BALQs are in a dust-enshrouded high-accretion phase. This is supported by polarization and reddening, and probably “eigenvector 1” properties. • Many have compact radio structure, even some of moderate radio-loudness, equatable with young, confined radio sources.
The Importance of BALQs: • BAL outflows may carry kinetic power comparable with accretion power. • Under hypotheses 1. and 2. BALQs are representative of many quasars, and/or represent a special (highly-fuelled) evolutionary phase. • Quasars are a high accretion-rate phase in black- hole growth. Powerful BAL winds may limit host galaxy bulge formation, producing the tight relationships between Mbh and bulge properties. • The inverse relationship of BAL strength & max. outflow velocity with radio-loudness must hold a strong clue that magnetic fields play a key role in confinement and/or acceleration of BAL outflows.
We discovered probable BALs in the radio-loud QSO, PKS 1004+13 (log R* = 2.32, z = 0.240), while searching the IUE archives. This was a surprise because BALs thought to avoid radio-loud quasars. PKS 1004+13 is a classical double-lobed radio source, with a small radio core/lobe ratio of 0.018 at 5GHz (rest), suggesting a very high inclination for a quasar central engine, roughly 50 deg. The high inclination is consistent with BAL outflows from a disk. FIRST radio image – 21 cm
Other properties of PKS 1004+13 Already, Elvis & Fabbiano (1984) showed that it was X-ray weak. Optical-UV spectropolarimetry showed 1-2% polarization increasing to the UV, attributed to scattered nuclear light (Stockman+84, Antonucci+96). First we present the evidence for BALs based on archival IUE spectra, together with high-resolution HST spectroscopy (GHRS and STIS). Second, we compare these archival results with our new STIS near-UV spectroscopy. We then summarize all the evidence, including that from our new spectropolarimetry.
Detail of the miniBAL absorption lines. Two redshift systems, z = 0.2364 and z=0.2387. The OVI l1034 doublet absorption in z = 0.2364 appears to cover 70-80% of the continuum source.
x Si IV
Our STIS spectra confirm the existence of BALs seen in earlier IUE spectra. The BALs changed drastically over 17-24 years! Depth IUE EW(rest) Width Max.outflow 50% CIV l1549 >8 A >5700 km/s >8500 km/s … SiIV l1397 >6 A >6300 km/s >6800 km/s STIS 7250 km/s CIV l1549 4.5 A 13100 km/s 30% … SIV l1397 2.3 A 5500 km/s 11500 km/s In 2003, the minimum outflow velocity has increased, that is, the trough became more detached, and shallower. Detachment is not simply dependent on orientation. It is not clear whether it is velocity or depth structure that changed. Such shallow troughs could easily be missed in surveys.
X-ray properties. The multiwavelength SED is compared with standard radio-quiet & radio-loud SEDs. Is PKS 1004+13 X-ray weak because of heavy X-ray absorption? Chandra and XMM-Newton spectra show evidence for complex, time-variable absorption with NH>1022cm-2 (B.Miller+06). Temorary figure is shown with Einstein X-ray upper limit, McDonald Observatory optical spectrum, HST and IUE archival spectra, 2MASS, and IRAS photometry, plus available radio flux densities: For update please see paper on astro-ph soon: Miller, Brandt, Gallagher,Laor, Wills & Garmire 2006
Optical-UV Polarization. Stockman+84 show low p% increasing to 1.7+-0.4% in the UV, with UV position angle ~ 55 deg. Antonucci+96 show p% increasing to short wavelengths, to p~2% at 4000A, with position angle ~81 deg. But T.Hurt finds an angle of 60 deg. between 3200 and 4000 A (Antonucci+96). Our spectropolarimetry from 3200A to 7500A shows p~1% with pol. position angle of 71+-2 deg. in the red to 64+-3 deg in UV. The radio position angle is 132 deg for the SE jet and -71 deg. for the NW. The optical-UV E-vector is not perpendicular to the jet, as might be expected for equatorial obscuration and scattering from gas in polar regions. However, the contribution of interstellar polarization and variability needs further investigation. PKS 1004 varies in optical magnitude ~0.5m on several-year time scales. This optical-UV variability, together with X-ray variability could provide a powerful probe of absorber/scatterer geometry.
Summary of PKS 1004+13 Results. • Weak BALs exist with outflow velocities >8500 km/s. • They are hiBALs. loBALs are not present. • The BAL shapes vary dramatically. • The X-rays are weak as a result of complex, variable absorption (Miller+06). • The significant low-level optical-UV polarization is characteristic of hiBAL quasars. • The total optical-UV flux, and opt.-UV polarization vary. • Narrow absorption (miniBALs) are present. • Consistent with scattering polarization, at least one NAL system shows evidence for partial covering. • The C IV l1549 miniBAL does not appear to vary.
Discussion PKS 1004+13 is now one of a handful of other known radio-loud BAL quasars (eg. Brotherton+05, Becker+00, Benn+05, Ma02). It’s the only one at low redshift, and the brightest in the optical-UV. The BALs, which are high-ionization BALs in PKS 1004, are weak, consistent with the inverse relationship between BAL EW and radio-loudness. Both polarization and miniBAL line ratios suggest partial covering; it is not clear whether the absorption occurs in the scattered or the direct light paths. The classical double-lobe radio structure and radio core-dominance suggests a high-inclination view of the central engine. Statistically, many radio-detected (not necessarily radio-loud) Many BALQs known variable, esp. in X-ray. Complex abs. appears responsible for X-ray ., and variability – probably in the absorbing column – is common in both RL and RQ BALQs.
HAPPY BIRTHDAYHAGAI Thanks to the organizers for their invitation, and for a wonderful meeting.