scholarly journals Short time-scale X-ray variability of Active Galactic Nuclei

2004 ◽  
Vol 132 ◽  
pp. 189-192
Author(s):  
Alexander V. Halevin
Keyword(s):  
Active Galactic Nuclei ◽  
Time Scale ◽  
Galactic Nuclei ◽  
Short Time Scale ◽  
X Ray ◽  
Short Time

scholarly journals Short Time Scale Variability of Active Galactic Nuclei: Einstein IPC Observations of PKS 2155-304 - A Report of Rapid Variations of Instrumental Origin

1989 ◽  
Vol 134 ◽  
pp. 106-107
Author(s):  
J. H. Beall ◽  
W. A. Snyder ◽  
K. S. Wood
Keyword(s):  
Active Galactic Nuclei ◽  
Time Scales ◽  
Time Scale ◽  
Galactic Nuclei ◽  
Short Time Scale ◽  
Background Region ◽  
Rapid Changes ◽  
Source Models ◽  
The Mean ◽  
Short Time

The Einstein IPC observed the bright (5 mCrab) X-ray emitting BL Lac Object PKS 2155-304 on 1979 November 4th and 5th through 7th and on 1980 May 16th through 18th. A total of 17.4 hours were spent monitoring the source. Changes in intensity of between 10–50% are evident in the data for time scales of days and months. The source was constant to within 10% of the mean intensity on hourly time scales for all intervals of data except one. Repeated factor of 2 variations in intensity, occuring on 10–30 second time scales, were observed during the first 50 minutes of the 1979 Nov. 5th observation. These variations, however, were anticorrelated with variations seen in an adjacent background region. Concurrent MPC observations also failed to confirm the rapid changes, although they should have been readily detected. Thus, we conclude that the observed rapid variations are not intrinsic to the source, but originated in the IPC. These results can have implications for other IPC reports of short time scale variability for active galaxies and for source models based on such observations.

scholarly journals IPS Observations of Short-Time Scale Interplanetary Activity

1996 ◽  
Vol 154 ◽  
pp. 225-228
Author(s):  
Pradeep Gothoskar ◽  
A. Pramesh Rao
Keyword(s):  
Time Scale ◽  
Solar Maximum ◽  
Component Model ◽  
Scintillation Index ◽  
Short Time Scale ◽  
High Time Resolution ◽  
The Sun ◽  
X Ray ◽  
Average Mass ◽  
Short Time

AbstractWe have carried out a program of continuous Interplanetary Scintillation (IPS) monitoring of the interplanetary activity using Ooty Radio Telescope (ORT). From May 1990 to March 1991, during the 22nd solar maximum, a few radio sources were monitored to provide long stretches of IPS data with a high-time resolution of few minutes. These observations covered 0.3 to 0.8 AU region (12° to 70° elongations) around the sun at several heliographic latitudes. During the observation, we detected 33 short-time scale IPS events which had significant variation in the scintillation index and solar wind velocity. These were considered to be due to travelling interplanetary disturbances.A multi-component model of plasma density enhancement was developed to estimate the geometry and physical properties of these IPS events. Detailed analysis of 20 of these events suggests, 1. fast IPS events were interplanetary signatures of Coronal Mass Ejections (CMEs), 2. the average mass and energy of these events was ~ 1016 gm and 1033 erg respectively, 3. 80% of IPS events were associated with X-ray flares on the sun and 50% were associated with geomagnetic activity at earth. Detailed study of the multi-component model suggests IPS observations at smaller elongations (hence at higher radio frequencies) are more suited to detect fast-moving interplanetary disturbances such as produced by CMEs.

Search for short time-scale periodicity in the X-ray flux of 4U1700 – 37

Nature ◽  
1979 ◽  
Vol 279 (5713) ◽  
pp. 508-509
Author(s):  
G. BRANDUARDI ◽  
A. K. DUPREE ◽  
P. W. SANFORD ◽  
G. S. G. POLLARD
Keyword(s):  
Time Scale ◽  
Short Time Scale ◽  
X Ray ◽  
Short Time

scholarly journals X-Ray Variability in Active Galactic Nuclei: Two Things That Everybody Should Know

1998 ◽  
Vol 11 (2) ◽  
pp. 804-807
Author(s):  
Karen M. Leighly
Keyword(s):  
Light Curve ◽  
Active Galactic Nuclei ◽  
Time Scales ◽  
Time Scale ◽  
Galactic Nuclei ◽  
X Rays ◽  
X Ray ◽  
Central Engine ◽  
Distinguishing Property

X-ray variability is a distinguishing property of Active Galactic Nuclei (AGN), and the energetics and time scales of the emission dictate that the X-rays must originate very close to the central engine. In this review I discuss two basic topics from AGN variability research. The first is the correlation of the variability time scale with the X-ray luminosity, and the second is the structure of the X-ray light curve. In each case, I first review the old results that have been known for approximately the last 10 years and then I discuss very new results which may force us to modify our ideas about the origin of AGN X-ray variability. Note that I am discussing the variability of non-blazar type AGN.

scholarly journals Recent Spectroscopy of X-Ray Sources and Systems Related to Cataclysmic Variables: I

1983 ◽  
Vol 72 ◽  
pp. 21-24
Author(s):  
A.P. Cowley ◽  
D. Crampton ◽  
J.B. Hutchings
Keyword(s):  
Emission Line ◽  
Time Scale ◽  
Cataclysmic Variables ◽  
Short Time Scale ◽  
X Ray ◽  
Spectroscopic Observations ◽  
Low Mass ◽  
Short Time

ABSTRACTWe present results of recent spectroscopic observations of A) some LMC X-ray sources, B) the X-ray burster 1735-44, and C) the peculiar emission-line binary BE UMa. From the short time scale variations and inferred low mass components each shows some similarities to more classical CV's.

scholarly journals Combined long and short time-scale X-ray variability of NGC 4051 withRXTEandXMM-Newton

2004 ◽  
Vol 348 (3) ◽  
pp. 783-801 ◽  
Author(s):  
I. M. McHardy ◽  
I. E. Papadakis ◽  
P. Uttley ◽  
M. J. Page ◽  
K. O. Mason
Keyword(s):  
Time Scale ◽  
Short Time Scale ◽  
X Ray ◽  
Ngc 4051 ◽  
Short Time
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