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Margon, B.

Publications and source records attributed to Margon, B..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

The x ray properties of a large, uniform QSO sample: Einstein observations of the LBQS

Although there are large numbers of Quasi Stellar Objects (QSO's) now observed in X rays, extensive X-ray observations of uniformly selected, 'complete' QSO samples are more rare. The Large Bright QSO Survey (LBQS) consists of about 1000 objects with well understood properties, most brighter than B = 18.8 and thus amenable to X-ray detections in relatively brief exposures. The sample is thought to be highly complete in the range 0.2 less than z less than 3.3, a significantly broader interval than many other surveys. The Einstein IPC observed 150 of these objects, mostly serendipitously, during its lifetime. We report the results of an analysis of these IPC data, considering not only the 20 percent of the objects we find to have positive X-ray detections, but also the ensemble X-ray properties derived by 'image stacking'.

Margon, B.↗
NASA NTRS1987

The early spectral phase of type Ib supernovae - Evidence for helium

A near-infrared spectrum and several optical spectra of SN 1983N obtained over a period from 10 days before maximum light to about a week after maximum and of SN 1984L from about maximum light to about 60 days later are presented. On the basis of these spectra it is argued that the first definite identification of helium in supernova ejecta near maximum light has been made. The emergence of oxygen emission lines which presage the dramatic transition to the supernebular phase is identified. Supernova atmosphere models which are consistent with the observations are presented, and it is argued that a strong departure of helium level populations from LTE is necessary. The current status of SNe Ib, the arguments that they result from core collapse in moderately massive stars, and some of the immediate work necessary to further clarify the nature of these events are summarized.

Harkness, R. P.↗
NASA NTRS1986

Discovery of a new short-period, eclipsing cataclysmic variable

Photometry and spectroscopy of a newly recognized 14th mag eclipsing cataclysmic variable, KPD 1911 + 1212 (= SVS 8130, V1315 Agl) are reported. The system exhibits deep (1.7 mag) eclipses with period 0.1397 day. The spectrum is that of a high-excitation old nova and shows dramatic variability of the emission line strengths through the eclipse. The profiles of the Balmer emission lines are also phase-dependent, with prominent absorption cores appearing briefly near the inferior conjunction of the emission line source. There is no direct evidence for the secondary. A preliminary determination of radial velocity variations at modest spectral resolution yields K = 132 + or - 26 km/s for the Balmer emission lines. A model is presented for the system consistent with current data, which implies a mass for the primary and secondary stars of 0.9 and 0.4 solar mass respectively and in inclination of i = 78 deg.

Downes, R. A.↗
NASA NTRS1986

A study of the discrepant QSO X-ray luminosity function from the HEAO-2 data archive

Sensitive X-ray information for approximately 90 previously uncataloged Quasi-Stellar Objects (QSOs) in the redshift range 1.8 is less than or equal to z which is less than or equal to 3. Even with the longest esixting Einstein Observatory X-ray exposures, only 25% of these objects are positively detected in X-rays. The data were used to investigate the ensemble X-ray properties of high redshift QSOs, and the QSO population in general.

Margon, B.↗
NASA NTRS1985

On the nature of M28 V7

It has recently been suggested that V7 in NGC6626 (M28) may be one of the few known cataclysmic variables in a globular cluster. The spectrum of the object was obtained, and the object was found instead to be near type M5III, and thus probably a normal Mira variable. However, if V7 is indeed a member of the cluster (which is far from certain), then it proves to be very interesting for an entirely different reason: it would represent the first high-amplitude Mira variable in a moderately metal-poor cluster.

Margon, B.↗
NASA NTRS1985

An atlas of X-ray-selected quasi-stellar objects

Coordinates, finding charts, photometry, and spectroscopy are presented for 55 X-ray selected QSOs. The selection technique, optical identification of X-ray sources observed serendipitously by the Einstein Observatory was used to find QSOs projected near bright galaxies, pairs of QSOs with similar redshifts; and low-redshift QSOs (z less than 0.5) which are well suited for imaging. Very luminous QSOs of more than 10 to the 46th ergs/s, and a very-high redshift X-ray-selected object were also found. It is suggested that most efforts to identify optically faint QSO counterparts to X-ray sources may yield intrinsically less luminous objects at redshifts less than 1 due to the weak influence of the limiting magnitude on the mean redshift of the sample. A complete list of the QSOs is given.

Margon, B.↗
NASA NTRS1985

KPD 0005 + 5106 - A post-PG 1159 type object?

In a survey for galactic plane UV-excess objects, a very hot (T about 100,000 K) helium-rich white dwarf is discovered. The object is spectroscopically similar to the pulsating PG 1159 class of stars, with narrow emission lines of He II, probably C IV, and possibly C III/N III, although there is no trace of carbon absorptions. Not all features have positive identifications. This object appears to be an old PG 1159 star, having ceased pulsations during evolution toward a more typical DO white dwarf.

Downes, R. A.↗
NASA NTRS1984

The extragalactic nature of H0323 + 022

H 0323 + 22, if galactic, is unprecedented in its radio and X-ray properties. A deep R-band image of the source shows it to be spatially extended, with significant light detectable 10 arcsec from the bright nucleus, thereby implying, in the event that it represents an underlying galaxy, that its distance is in the 0.5-1.5 Gpc range and that its radio, optical, and X-ray luminosities are typical of other BL Lac objects. The G star-like absorption spectrum, however, then remains to be explained. Because the two closest bright optical objects also exhibit G star spectra, it is suggested that the Doxsey et al. (1983) G spectra are due to misidentification of the object. H 0323 + 22 is both extragalactic and probably similar to other X-ray selected BL Lac objects.

Margon, B.↗
NASA NTRS1984

The extragalactic nature of H0323+022

Imaging and spectroscopic observations probed the nature of the X-ray source H0323+022. It is suggested that H0323+022 is extragalactic, and similar to a variety of other X-ray selected BL Lac objects. The extended image, when combined with estimates of the linear size of an underlying galaxy, implies both visible and X-ray luminosities consistent with this hypothesis. In a stellar interpretation, the angular extension would require attributing yet another unique feature to the object. The interpretation of the stellar absorption spectrum as misidentification of the object at the telescope is supported. Two candidates for that unrelated stellar object, which are also the next closest bright visible objects to the X-ray source are proposed. It is predicted that the late type absorption spectrum will never again be seen in H0323+022.

Margon, B.↗
NASA NTRS1984

The X-ray properties of high-redshift, optically selected QSOs

The X-ray properties of high redshift quasars were probed using grism/grens plates covering 13 sq deg of sky imaged to very sensitive X-ray flux levels with the Imaging Proportional Counter on the Einstein Observatory. Optical magnitudes are estimated from image diameter measurements to obtain an X-ray flux detection, or a sensitive X-ray flux upper limit, from the IPC image. Eleven out of 52 optically selected quasars are detected in X-rays at 3 sigma. The alpha ox value is 1.49 + or - 0.04 for the 52 objects.

Anderson, S. F.↗
NASA NTRS1984

An unsuccessful search for very extended halos around NGC 1300 and M61

The results of a search for H and K absorption in the halos of the two spiral galaxies projected against background QSOs are presented. The search was carried out using the blue-sensitive spectrograph attached to the Multiple Mirror Telescope (MMT). Despite good sensitivity (S/N of about 20) and high spectral resolution (1 A), no H and K absorption was found. Schematic illustrations of the nuclear and halo spectra of M61 and NGC 1300 are provided.

Bothun, G. D.↗
NASA NTRS1984

Rapid intensity variability in the jets of SS 433

The 'moving' emission lines in the spectrum of SS 433 can disappear entirely on a time scale of less than 1 day, remain absent for at least a few days, and reappear equally rapidly. Examples of both disappearance and reappearance episodes are presented. While the majority of SS 433 spectra clearly do show the moving features, isolated spectra lacking the Doppler-shifted lines must now not be regarded as highly unusual. The extreme intensity variability is found to be synchronized in both the red- and blueshifted emission systems, providing an upper limit of 100 AU to the separation of the two relativistic emitting regions. On some occasions the intensity and profile of emission lines from these two separate regions can be identical to very high accuracy, again suggesting that the majority of the relativistic gas originates in a common, compact region.

Margon, B.↗
NASA NTRS1984

The underlying galaxies of X-ray-selected quasars

Deep red images of 24 X-ray selected quasars were obtained using the SIT Area Photometer on the Palomar 1.5 meter telescope. About half were also imaged through green and violet filters. The images of all 15 of the quasars with redshifts up to 0.4 certainly are extended and the two at z = 0.45 probably are extended. The remainder of higher redshift are unresolved, presumably because they are too distant. The resolved structures are 10-30 in. across, symmetric, and centered on the point-like quasar nuclei. For most of the quasars the nuclear light and the extended emission can be roughly separated. Evidence that the extended emission is starlight from a surrounding galaxy is presented, permitting several properties of the host galaxy to be deduced. Its colors, surface brightness, linear extent, ellipticity, and frequent association with groups of galaxies indicate that it is usually a normal spiral galaxy.

Malkan, M. A.↗
NASA NTRS1983

A QSO in a rich, distant cluster of galaxies

The detection of a 'classical' QSO in a previously studied, distant rich cluster of visible galaxies is reported. The blue and red/IR spectra of the QSO are shown. The QSO occurs at a redshift essentially identical to that of the cluster 0016+16, colocated on the 0.01 of the plate which contains the cluster. The simplest explanation of this association is that the QSO is a member of the cluster. The consequences of the finding are discussed. The QSO-cluster association is further confirmation of the cosmological nature of QSO-cluster association is further confirmation of the cosmological nature of QSOs, and it suggests that QSOs do not necessarily avoid the environment of rich clusters. The fact that this QSO is not well centered adds credence to the suggestion that 3C345 and QSO 1641+3998 constitute an additional case of QSOs in high redshift cluster. The location of this QSO could make it a unique probe to study the physical state of the intracluster gas that is common in rich clusters.

Margon, B.↗
NASA NTRS1983

An optical search for 'X-ray quiet' quasars

Recent progress is described in an ongoing program to develop criteria for selecting faint QSOs in several tens of square degrees of sky previously surveyed by the Einstein X-ray Observatory. The physical properties of the selected QSOs are discussed in terms of the difficulties they present for QSO X-ray detection techniques. A series of F-plates for about two dozen fields have been obtained, but only a few of the X-ray images have been analyzed. The analysis of the plates consists of scanning several times with a binocular microscope. The number of positively identified QSOs per plate is 3, with a limiting magnitude of about 21 B. For about one half of the candidates, more than one emission line is identified at a consistent redshift, confirming that the object is a QSO. A table is presented which lists some of the flux density and luminosity data for the QSO objects detected thus far.

Anderson, S. F.↗
NASA NTRS1982

Two X-ray selected BL Lacertae candidates

Two serendipitous Einstein Observatory X-ray sources with faint (V approximately 19) optical counterparts having the featureless spectra characteristic of BL Lacertae objects are identified. Observations with the VLA at 6 cm establish that these sources have radio to optical luminosity ratios which are lower than the mean for BL Lac objects by one to two orders of magnitude but which are not extreme when compared with those of the known X-ray bright BL Lac objects. It is therefore suggested that these two objects are among the first examples of radio-quiet BL Lac objects.

Chanan, G. A.↗