摘要:

We derive a constraint on the pair density ratio,z+=n+/npin an electron‐positron pair wind flowing away from the central region of an accretion disk around a compact object under the assumption of a coupling between electrons, positrons, and protons. The observed annihilation flux per unit volume is used to determine a minimum mass loss rate per unit area,M˙*, for a given pair density ratio at the base of the streamline. The requirement thatM˙*<M˙*,Edd(the mean Eddington mass loss rate per unit area) then places a lower limit on the pair density ratio at the base of the wind,z+,min. The GRANAT/SIGMA experiment observed a positron annihilation line in Nova Muscae 1991. The narrow width and redshift of the line suggest that the pair production and annihilation regions are physically distinct. We hypothesize that an electron‐positron pair wind transports the pairs from the production to the annihilation region and calculatez+,min. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.45993

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The concept of the black hole was derived from the Schwarzchild metric which was then the only exact and reliable solution of Einstein’s field equations (R&mgr;&sgr;=0). That metric gives a coordinate velocity for electromagnetic radiation (EMR) that goes to zero at the Schwarzchild radius, thereby resulting in the black hole. This analysis shows that inherent in the Schwarzchild solution is the assumption that the velocity of EMR in a gravitational field is independent of wavelength and frequency. An alternate exact solution is derived making the opposite assumption. The resulting metric’s properties include: a) the coordinate velocity of light is frequency dependent and does not predict a black hole and b) the mass parameter has dimensions of volume unlike Schwarzchild’s geometric mass parameter. The implications of these results are discussed. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.45994

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present new photometric observations of the GRO transient J0422+32 which show a two‐hour and a five‐hour variation of only 0.1 magnitude in amplitude. Spectroscopic observations during the late decline of the August 1992 outburst and during the August 1993 outburst show variability in the double‐peaked Balmer and He iiprofiles on a timescale of hours and reveal red‐shifted emission components at two epochs. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.45995

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

TheBATSEexperiment on‐board the Compton Gamma Ray Observatory (CGRO) reported the detection of a new source of hard x‐rays in the direction of the constellation Perseus on 5 August 1992 (Paciesasetal. 1992). The transient was subsequently classified an x‐ray nova (XRN), and designated GRO J0422+32 (herein J0422+32). In this contribution, we describe some results of a multi‐wavelength campaign designed to study J0422+32 at ultraviolet, optical, and radio wavelengths. Our coverage began approximately 10 days post‐discovery and has continued through the decline phase. A definitive astrometric determination of the optical counterpart, the progenitor, long‐ and short‐term photometric variability including possible periodicity, distance estimates, energetics, and comparisons to previous XRN are discussed. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.45996

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present the results of a photometric and spectroscopic study of the optical counterpart of the x‐ray nova J0422+32, a recently discovered black hole candidate. Its light curve shows a similar decay pattern to that of other novae black hole candidates, but with a slower decay rate. Its rapid decline started 240 days after the outburst. Its current magnitude is R∼19.4, which is still brighter than its quiescent value. Intensive photometry in January 1993 shows evidence of the 5.1 hour modulation reported by other groups. However, this modulation is not present in data taken in October 1992 and October 1993. Outburst spectra of J0422+32 are remarkably similar to those of Nova Muscae 1991 (a strong black‐hole candidate) including double peaked emission lines of H&agr;, H&bgr;, H&ggr;, He ii4686 A˚, He i5876 A˚ and 6678 A˚. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.45997

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We hereby present spectroscopic and photometric observations of the Nova Persei 1992=GRO J0422+32 obtained at the Special Astrophysical Observatory and at the Bologna Observatory. Our observations show that different outbursts are driven by different mechanisms of accretion. We have interpreted the optical activity we observed on an ultrashort time scale as indicative of non‐thermal processes in accretion structures around the compact object. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.46025

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

New high resolution (0.8 A˚) H&agr; spectroscopy provides further constraints on the orbital parameters of the black hole candidate V404 Cyg. Our updated mass function is now 6.08±0.06 M⊙which confirms V404 Cyg as the most important black hole candidate yet found. We also resolve the rotational broadening of the secondary star which yields the lowest mass ratio ever measured (q=Mc/Mx=0.050). The mass of the black hole is now restricted to the range 7–29 M⊙. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.46026

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The results of a ROSAT observation of V404 Cygni are described and discussed. The 0.2–2.4 keV light curve of V404 Cyg exhibits substantial variability on time scales of less than a day. The observed x‐ray spectrum can be described equally well by either a blackbody, power law, or a thermal bremsstrahlung continuum and interstellar absorption column densities in excess of log NH(cm−2)&bartil;22.1. Both optical and radio measurements suggest that log NH&bartil;21.7 so that some internal absorption of x‐rays, presumably in the accretion disk surrounding the compact object, is required to fully explain the observations. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.46027

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

TheComptonBurst and Transient Source Experiment (BATSE) detected hard x‐ray flux from Nova Muscae 1991 (GS/GRS 1124–68) during an interval of ∼100 days beginning ∼130 days after the January 1991 main outburst. The light curve during this secondary outburst is roughly symmetric, reaching a maximum around mid‐July 1991 at an intensity of ∼15% of the peak intensity during the main outburst. The hard x‐ray spectrum displays a soft‐to‐hard evolution during the rise to maximum; the post‐maximum spectral evolution is less well determined. We compare our observations with those of theGRANAT/SIGMA experiment, which covered the initial outburst well but missed most of the secondary outburst. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.46028

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present theBBXRTspectrum of the black hole candidate LMC X‐1. The spectrum cannot be fit by a simple model, but requires a soft disk blackbody component and a power law tail, confirming earlier studies. The blackbody disk component is essentially unchanged since theGingameasurement in 1987. We report a 95% confidence detection of weak emission features at ∼5.1 keV and ∼7.3 keV; if attributed to Fe I K&agr; at 6.39 keV, when the redshift is ∼0.19. No quasi‐periodic behavior is found in the data at this epoch. ©1994 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.46041

出版商:AIP    

年代:1994

数据来源: AIP