Low energy y-ray observations with the MISO telescope

1981 ◽  
Vol 301 (1462) ◽  
pp. 603-606
Keyword(s):  
Seyfert Galaxy ◽  
Effective Area ◽  
Low Energy ◽  
Field Of View ◽  
Total Period ◽  
X Ray ◽  
Ngc 4151 ◽  
Orientation System ◽  
The Mean ◽  
Right Ascension

The MISO telescope, which has been described elsewhere, (Baker et al. 1979), has a sensitive area of 560 cm 2 and an aperture of 3° f.w.h.m. in both the azimuthal and zenithal planes. An alt—azimuth orientation system was used to point the telescope with a precision of ± 20'. A passively shielded hard X-ray detector (20—280 keV) having an effective area of 600 cm 2 was also mounted in parallel with the axis of the main telescope and had a field of view of 3° x 3° f.w.h.m. This instrument was used to study the region of the sky containing NGC 4151 on 30 September 1979 between 15h01 U.T. and 20h40 U.T. A series of five drift scans were performed to survey the region contained within the coordinate points 11h32 and 12h33 in right ascension. The declination was centred on + 39.8°. The Seyfert galaxy NGC 4151 was in the field of view of the telescope for a total period of 7.5 x 10 3 s. The total time spent on the background measurements associated with the data presented here, was 8.6 x 10 3 s. The mean float altitude during the observation was close to 4 mbar (400 Pa) and the telescope was set at a series of zenith angles between 9° and 30°.

scholarly journals Searching for fast extragalactic X-ray transients in Chandra surveys

2019 ◽  
Vol 487 (4) ◽  
pp. 4721-4736 ◽  
Author(s):  
G Yang (杨光) ◽  
W N Brandt ◽  
S F Zhu (朱世甫) ◽  
F E Bauer ◽  
B Luo (罗斌) ◽  
...  
Keyword(s):  
Event Rate ◽  
Large Population ◽  
Physical Nature ◽  
Effective Area ◽  
The Other ◽  
Field Of View ◽  
Stellar Objects ◽  
Large Sample ◽  
X Ray ◽  
Future Work

ABSTRACT Recent works have discovered two fast (≈10 ks) extragalactic X-ray transients in the Chandra Deep Field-South (CDF-S XT1 and XT2). These findings suggest that a large population of similar extragalactic transients might exist in archival X-ray observations. We develop a method that can effectively detect such transients in a single Chandra exposure, and systematically apply it to Chandra surveys of CDF-S, CDF-N, DEEP2, UDS, COSMOS, and E-CDF-S, totaling 19 Ms of exposure. We find 13 transient candidates, including CDF-S XT1 and XT2. With the aid of available excellent multiwavelength observations, we identify the physical nature of all these candidates. Aside from CDF-S XT1 and XT2, the other 11 sources are all stellar objects, and all of them have z-band magnitudes brighter than 20. We estimate an event rate of ${59^{+77}_{-38}\ \rm {evt\ yr^{-1}\, deg^{-2}}}$ for CDF-S XT-like transients with 0.5–7 keV peak fluxes log Fpeak ≳ −12.6 (erg cm−2 s−1). This event rate translates to ${\approx 15^{+20}_{-10}}$ transients existing among Chandra archival observations at Galactic latitudes |b| > 20°, which can be probed in future work. Future missions such as Athena and the Einstein Probe with large grasps (effective area × field of view) are needed to discover a large sample (∼thousands) of fast extragalactic X-ray transients.

scholarly journals X-Ray Properties of Galactic Nuclei

1980 ◽  
Vol 5 ◽  
pp. 623-630
Author(s):  
Daniel W. Weedman
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Strong Emission ◽  
X Ray ◽  
Ngc 4151 ◽  
Survey Results ◽  
Emission Line Galaxies

Preparing this review was my just punishment for stating only two years ago - in another review (Weedman 1977) - that Seyfert galaxies are not strong X-ray sources. I said that because, as recently as three years ago, NGC 4151 was the only Seyfert galaxy known as an X-ray source. Now we have 36 Seyfert 1 galaxies, along with 12 other galaxies with strong emission-line nuclei, that are X-ray sources. And this is all without even having HEAO-2 data at our disposal yet. The study of active galactic nuclei with X-ray astronomy is progressing so rapidly that a reviewer feels almost hopeless. The best I can do is summarize what is known as of the summer of 1979 and give a simple overview of how X-ray and other properties relate.Some excellent reviews of the X-ray properties of Seyfert and other emission-line galaxies already exist. I especially recommend that by Andrew Wilson (1979). He provides very complete references as of a year ago, but X-ray astronomy is progressing so rapidly that he then had only somewhat more than half the active nuclei now in Tables 1 and 2. It was the group working with the Ariel V SSI that made the initial comprehensive X-ray studies of Seyfert galaxies (Ward et al. 1977, Elvis et al. 1978). The UHURU results for Seyfert galaxies followed soon after and are summarized by Tananbaum et al. (1978); the HEAO-A-2 survey results are now in press (Marshall et al. 1979) I have tried to incorporate these and other recent results in Tables 1 and 2.

X-ray calibration of the AXAF Low Energy Transmission Grating Spectrometer: effective area

1997 ◽  
Author(s):  
Peter Predehl ◽  
Heinrich W. Braeuninger ◽  
A. C. Brinkman ◽  
Daniel Dewey ◽  
Jeremy J. Drake ◽  
...  
Keyword(s):  
Effective Area ◽  
Low Energy ◽  
Energy Transmission ◽  
X Ray ◽  
Title X ◽  
Transmission Grating ◽  
Grating Spectrometer

scholarly journals Recent Results on Extragalactic Cosmic X-Ray Sources from Rocket and Balloon Flights

1968 ◽  
Vol 1 ◽  
pp. 184-187
Author(s):  
G. W. Clark
Keyword(s):  
Radio Galaxy ◽  
Effective Area ◽  
Field Of View ◽  
X Ray ◽  
Beryllium Window ◽  
Proportional Counters

Two experiments carried out recently at M.I.T. gave results which bear on the problems of extragalactic X-ray sources. One of these is the work of a group under the direction of Hale Bradt (Bradt et al., 1967), who used an attitude-controlled Aerobee rocket to scan a portion of the sky which included the radio galaxy M 87 (Virgo A). Among their detectors were two banks of argon-filled, 2 mil beryllium window proportional counters, each with an effective area of 350 cm2 and a mechanical collimator giving a 2° × 20° FWHM field of view. The fields of view were crossed so that their long directions made an angle of 60° with one another. Aspect was determined to within 5 min of arc by star photography.

scholarly journals Recent High Resolution X-Ray Spectra of the Sun

1972 ◽  
Vol 14 ◽  
pp. 740-741
Author(s):  
J. H. Parkinson ◽  
K. Evans ◽  
K. A. Pounds
Keyword(s):  
High Resolution ◽  
Active Region ◽  
Wavelength Range ◽  
South Australia ◽  
Active Regions ◽  
Effective Area ◽  
Field Of View ◽  
The Sun ◽  
X Ray

New results are presented from high resolution Bragg crystal spectrometers flown in late 1970 on two Skylark rockets. The first instrument, launched on 24 November 1970 at 22 13 UT from Woomera, South Australia, contained two crystal spectrometers, each with an effective area of 50 cm2 and field collimation to 3’ FWHM. This instrument obtained the X-ray spectrum of the quiet corona in the wavelength range 5–14 Å. The second instrument was launched on 6 December 1970 at 11 13 UT from Sardinia, Italy, and contained four crystals of 6 cm2, each collimated to 4’ FWHM. This instrument was pointed at a non-flaring active region near N20 W40(McMath region 11060), and obtained an X-ray spectrum between 5 and 23 Å. This first use of a collimator to limit the field of view has considerably increased the spectral clarity compared with earlier observations by excluding the contributions of other active regions.

scholarly journals The Properties of Extragalactic X-Ray Sources from Visible Light Observations

1973 ◽  
Vol 55 ◽  
pp. 184-198
Author(s):  
Wallace L. W. Sargent
Keyword(s):  
Radio Galaxy ◽  
Low Frequency ◽  
Seyfert Galaxy ◽  
Point Sources ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Detailed Structure ◽  
X Ray ◽  
Radio Halo ◽  
Ngc 4151

We describe the optical properties of the radio galaxy NGC 5128, the Seyfert galaxy NGC 4151 and the QSO 3C 273 all of which appear to be point sources of X-rays. We emphasize how the X-ray observations, particularly the low energy absorption cutoff, may help us to understand the detailed structure and source of energy in these diverse objects.The clusters of galaxies in Virgo, Perseus, Coma and Centaurus, all associated with extended X-ray sources are described. They have diverse shapes, central concentrations and galactic populations, but all contain a radio galaxy and, in several cases, a low frequency radio halo around it. It is concluded that the X-ray emission is likely to be non-thermal in origin.

scholarly journals Simultaneous Ultraviolet and X‐Ray Observations of Seyfert Galaxy NGC 4151. I. Physical Conditions in the X‐Ray Absorbers

2005 ◽  
Vol 633 (2) ◽  
pp. 693-705 ◽  
Author(s):  
S. B. Kraemer ◽  
I. M. George ◽  
D. M. Crenshaw ◽  
J. R. Gabel ◽  
T. J. Turner ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
X Ray ◽  
Physical Conditions ◽  
Ngc 4151

Concurrent radio, infrared, optical and X-ray observations of the nucleus of the Seyfert galaxy NGC 4151

1981 ◽  
Vol 247 ◽  
pp. 458 ◽  
Author(s):  
J. H. Beall ◽  
W. K. Rose ◽  
B. R. Dennis ◽  
C. J. Crannell ◽  
J. F. Dolan ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
X Ray ◽  
Ngc 4151

Variable X-ray Absorption in NGC 4151

1989 ◽  
Vol 134 ◽  
pp. 182-183
Author(s):  
R. S. Warwick ◽  
T. Yaqoob ◽  
K. A. Pounds
Keyword(s):  
Seyfert Galaxy ◽  
Spectral Form ◽  
Iron Line ◽  
X Ray ◽  
Ngc 4151 ◽  
Hard Power ◽  
Edge Features ◽  
Partial Covering ◽  
Covering Model ◽  
X Ray Absorption

The medium energy X-ray spectrum of the Seyfert galaxy NGC 4151 is characterised by a hard power-law continuum, a variable low-energy cut-off and iron line and edge features. Holt et al. (1980) found the spectral form below 4 keV to be incompatible with absorption in a uniform screen of cold gas and interpreted the apparent soft X-ray excess in terms of a partial covering model. However, recent observations point to a somewhat different description of the X-ray absorbing medium present in the nucleus of this galaxy.

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