Edward Beaver

LBQS 0103–2753: A 0.″3 Binary Quasar*

Imaging and spectroscopy with HST show that LBQS 0103-2753 (V = 17.8, z = 0.848) is a binary quasar with a separation of 0.3 arcsec or 2.3 kpc. This is by far the smallest separation binary quasar reported to date. The two components have very different spectra, including the presence of strong broad absorption lines (BALs) in component A only. The emission-line redshifts, based on the broad high ionization C IV lines, are z_A = 0.834 and z_B = 0.858; their difference is 3900 km/s in velocity units. The broad C IV lines, however, are probably not a good indicator of systemic redshift; and LBQS 0103-2753 A and B could have a much smaller systemic redshift difference, like the other known binary quasars. If the systemic redshift difference is small, then LBQS 0103-2753 would most likely be a galaxy merger that has led to a binary supermassive black hole. There is now one known 0.3 arcsec binary among roughly 500 QSOs that have been observed in a way that would reveal such a close binary. This suggests that QSO activity is substantially more likely for black hole binaries at spacings ~2 kpc than at ~15 to 60 kpc. Between 1987 and 1998, the observed Mg II BAL disappeared.

A digital multichannel photometer

A semiconductor diode image tube system has been built which has the characteristics of a good photomultiplier tube but which can simultaneously measure light intensity at 38 different positions. Tube dark current is 0.02 count/sec/position. A tube with up to 1000 elements appears feasible.

The Dust-to-Gas Ratio in the Damped Lyα Clouds toward the Gravitationally Lensed QSO 0957+561

We present HST/FOS spectra of the two bright images (A and B) of the gravitationally lensed QSO 0957+561 in the wavelength range 2200-3300 A. We find that the absorption system (zabs = 1.3911) near zem is a weak, damped Lyα system with strong Lyα absorption lines seen in both images. However, the H I column densities are different, with the line of sight to image A intersecting a larger column density. The continuum shapes of the two spectra differ in the sense that the flux level of image A increases more slowly toward shorter wavelengths than that of image B. We explain this as the result of differential reddening by dust grains in the damped Lyα absorber. A direct outcome of this explanation is a determination of the dust-to-gas ratio, k, in the damped Lyα system. We derive k = 0.55 ± 0.18 for a simple 1/λ extinction law and k = 0.31 ± 0.10 for the Galactic extinction curve. For gravitationally lensed systems with damped Lyα absorbers, our method is a powerful tool for determining the values and dispersion of k, and the shapes of extinction curves, especially in the FUV and EUV regions. We compare our results with previous work.

AO 0235+164 and Surrounding Field: Surprising HST Results

Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and gamma-ray emitting QSO (or BL Lac object) AO 0235 + 164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235 + 164 was bright (m approx. 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO following the nomenclature of Yanny et al. (1989), the companion object named A, 2 sec south of AO, is discovered not to be an elliptical galaxy as hypothesized earlier, but to be an AGN object, with a central UV-bright point-source nucleus and faint surrounding nebulosity extending to AO. The second companion object 1.3 sec east of AO discovered by Yanny et al. (1989) and named object Al, appears more like a normal spiral galaxy. We have measured the positions, luminosities, and colors of some 30 faint objects in the field around AO 0235 + 16; most are extended and may be star-forming galaxies in a loose group or cluster. Our most surprising result of the HST observations comes from FOS spectra obtained in 1995 July, discussed in Sec. 4. Because of a positioning error of the telescope and AOs faintness at that time (m approx. 20), object A was observed instead of the intended target AO. Serendipitously, we discovered A to have broad deep BALQSO-type absorptions of C IV, Si IV, N V shortward of broad emissions. A is thus ejecting high velocity, highly ionized gas into the surrounding IGM. We discuss in Sec. 5 the relationship of the objects in the central 10 sec X 1O sec region around AO, where redshifts z(sub e) = 0.94, z(sub a) = 0.524, 0.851 in AO, (sub e) = 0.524 and Z(sub BAL)=0.511 in A, are found. We hypothesize that some of the 30 faint objects in the 77 sec. x 77 sec. field may be part of a large star-forming region at z approx. 0.5, as suggested for a few objects by Yanny et al. (1989). The proximity of two highly active extragalactic objects, AO 0235+164 and its AGN companion A, is remarkable and one of the authors (EMB) suggests it may require consideration of a non-cosmological component of redshift in AO 0235+164.

Discovery of a magnetic DA white dwarf

The spectrum of the white dwarf suspect, GD 90, is shown to contain broad Balmer lines with resolved Zeeman structure. All the observed features correspond to the calculated spectrum of hydrogen at 5 plus or minus 0.5 MG. A region of approximately 20% of the observed stellar disk must be subject to a reasonably uniform field of this strength. The sigma components of the Zeeman patterns in H beta and H gamma are found to be circularly polarized, indicating that the field has a component directed along the line of sight. There is evidence for an additional stronger and less homogeneous field, as would be expected if the dominant 5 -MG region were at the equator of a dipolar field.

Far-ultraviolet spectroscopy of the quasar UM 675 with the faint object spectrograph on the Hubble Space Telescope

To investigate the far-UV spectral properties of a QSO and to look for evidence of He I 584 A emission and absorption the Faint Object Spectrograph aboard the HST was used to observed UM 675. Light is detected down to 520 A in the object in the rest frame and limits are set to He I emission, the He I Gunn-Peterson effect at z = 2.148, and Ly-alpha absorption at z roughly 0.5. 15 refs.

A 21 Centimeter Absorber Identified with a Spiral Galaxy: Hubble Space Telescope Faint Object Spectrograph and Wide-Field Camera Observations of 3CR 196

We present imaging and spectroscopy of the quasar 3CR 196 (z(sub e) = 0.871), which has 21 cm and optical absorption at z(sub a) = 0.437. We observed the region of Ly alpha absorption in 3CR 196 at z(sub a) = 0.437 with the Faint Object Spectrograph on the Hubble Space Telescope. This region of the spectrum is complicated because of the presence of a Lyman limit and strong lines from a z(sub a) approx. z(sub e) system. We conclude that there is Ly alpha absorption with an H I column density greater than 2.7 x 10(exp 19) cm(exp -2) and most probably 1.5 x 10(exp 20) cm(exp -2). Based on the existence of the high H I column density along both the optical and radio lines of sight, separated by more than 15 kpc, we conclude that the Ly alpha absorption must arise in a system comparable in size to the gaseous disks of spiral galaxies. A barred spiral galaxy, previously reported as a diffuse object in the recent work of Boisse and Boulade, can be seen near the quasar in an image taken at 0.1 resolution with the Wide Field Planetary Camera 2 on the HST. If this galaxy is at the absorption redshift, the luminosity is approximately L(sub *) and any H I disk should extend in front of the optical quasar and radio lobes of 3CR 196, giving rise to both the Ly alpha and 21 cm absorption. In the z(sub a) approx. z(sub e) system we detect Lyman lines and the Lyman limit, as well as high ion absorption lines of C III, N V, S VI, and O VI. This absorption probably only partially covers the emission-line region. The ionization parameter is approximately 0.1. Conditions in this region may be similar to those in broad absorption line QSOs.

The spectrum of OH 471 /0642+44/

Results of image-tube and Digicon spectroscopy of OH 471 (0642+44) are reported. Wavelengths of 89 stronger absorption features in the range 4000-6000 A are given, and a number of absorption redshift systems are suggested. The lack of radiation shortward of 4000 A is attributed to Lyman continuum absorption in the gas giving rise to the various absorption-line systems.

Conditions in the z = 0.692 absorber toward 3CR 286

We present Hubble Space Telescope/Faint Object Spectrograph (HST/FOS) ultraviolet and ground-based optical spectra of the z = 0.692 21 cm absorption system in the quasi-stellar object (QSO) 3CR 286. The strength of the damped Lyman-alpha absorption implies an H I column density, N(H I) approximately 2 x 10(exp 21)/sq cm. We derive a high spin temperature for the H I gas, T(sub s) greater than or approximately equal to 10(exp 3) K, as has been found for other high-redshift 21 cm absorbing systems; at least 80% of the H I is hotter than 1200 K. Curve-of-growth analysis yields Mg(+) and Fe(+) abundances which are approximately 1-2 dex below solar values; the Ca(+) abundance is even lower implying some depletion onto dust grains. The H2 fraction is not high. We speculate that the high inferred T(sub s) for the gas may reflect continuing active star formation at the 5-8 Gyr look-back time to the absorbing galaxy.

Charge -coupled device (CCD) Digicon detector system concepts

A next logical step in the progression of state-of-the-art detector systems for use in astronomical observations is seen to be the development of an intensified charge-coupled device (ICCD) system, involving the incorporation of a thinned backside-illuminated CCD as the anode of a Space Telescope design Digicon tube. This concept extends the demonstrated fundamental photon counting accuracy, low background, sensitivity, and stability of the Digicon to the two-dimensional capabilities of CCDs. In particular, the CCD-Digicon combination enables (1) the use of magnetic deflection in order to take full advantage of the basic resolution elements in the system and to enhance the uniformity of elemental response, and (2) charge pulse centroiding to substantially increase the number of effective detector resolution elements without straining manufacturing techniques as would be required to produce such amounts of physical array cells. Results of recent investigations into the feasibility and characteristics of these techniques are presented.