Detection of TeV photons from the active galaxy Markarian 421 View Full Text


Ontology type: schema:ScholarlyArticle      Open Access: True


Article Info

DATE

1992-08

AUTHORS

M. Punch, C. W. Akerlof, M. F. Cawley, M. Chantell, D. J. Fegan, S. Fennell, J. A. Gaidos, J. Hagan, A. M. Hillas, Y. Jiang, A. D. Kerrick, R. C. Lamb, M. A. Lawrence, D. A. Lewis, D. I. Meyer, G. Mohanty, K. S. O'Flaherty, P. T. Reynolds, A. C. Rovero, M. S. Schubnell, G. Sembroski, T. C. Weekes, T. Whitaker, C. Wilson

ABSTRACT

PHOTONS of TeV energy have been observed from a few sources in our Galaxy, notably the Crab Nebula1. We report here the detection of such photons from an extragalactic source, the giant elliptical galaxy Markarian 421. Mk 421 has a nucleus of the BL Lacertae type2,3, and emission from it has been observed at radio4–6, optical3,6 and X-ray6–8 frequencies, and most recently in the MeV-GeV bands, by the EGRET detector aboard the Compton observatory9. In March–June 1992, we observed Mk 421 with the Whipple Observatory γ-ray telescope10, a ground-based detector that images Cerenkov light from air showers, and found a signal with statistical significance of 6er above background. The flux above 0.5 TeV is 0.3 of that from the Crab Nebula. The source location agrees with the position of Mk 421 within the angular uncertainty (6 arc minutes) of the Whipple instrument. The fact that we have observed this relatively nearby source (redshift z = 0.031), whereas active galaxies and quasars that are brighter at EGRET energies but more distant have not been detected in the TeV energy range, may be consistent with suggestions11,12 that TeV photons are strongly attenuated by interaction with extragalactic starlight. More... »

PAGES

477-478

References to SciGraph publications

Identifiers

URI

http://scigraph.springernature.com/pub.10.1038/358477a0

DOI

http://dx.doi.org/10.1038/358477a0

DIMENSIONS

https://app.dimensions.ai/details/publication/pub.1002652464


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7 schema:description PHOTONS of TeV energy have been observed from a few sources in our Galaxy, notably the Crab Nebula1. We report here the detection of such photons from an extragalactic source, the giant elliptical galaxy Markarian 421. Mk 421 has a nucleus of the BL Lacertae type2,3, and emission from it has been observed at radio4–6, optical3,6 and X-ray6–8 frequencies, and most recently in the MeV-GeV bands, by the EGRET detector aboard the Compton observatory9. In March–June 1992, we observed Mk 421 with the Whipple Observatory γ-ray telescope10, a ground-based detector that images Cerenkov light from air showers, and found a signal with statistical significance of 6er above background. The flux above 0.5 TeV is 0.3 of that from the Crab Nebula. The source location agrees with the position of Mk 421 within the angular uncertainty (6 arc minutes) of the Whipple instrument. The fact that we have observed this relatively nearby source (redshift z = 0.031), whereas active galaxies and quasars that are brighter at EGRET energies but more distant have not been detected in the TeV energy range, may be consistent with suggestions11,12 that TeV photons are strongly attenuated by interaction with extragalactic starlight.
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14 schema:keywords BL Lacertae
15 Cerenkov light
16 Compton observatory9
17 Crab Nebula
18 Crab Nebula1
19 EGRET detector
20 EGRET energies
21 Lacertae
22 MK-421
23 MeV-GeV bands
24 Nebula1
25 Observatory γ
26 TeV energies
27 TeV energy range
28 Whipple Observatory γ
29 Whipple instrument
30 active galaxies
31 active galaxy Markarian 421
32 air showers
33 angular uncertainty
34 background
35 band
36 detection
37 detector
38 elliptical galaxy Markarian 421
39 emission
40 energy
41 energy range
42 extragalactic sources
43 extragalactic starlight
44 fact
45 flux
46 frequency
47 galaxies
48 galaxy Markarian 421
49 giant elliptical galaxy Markarian 421
50 ground-based detectors
51 instrument
52 interaction
53 light
54 location
55 nearby sources
56 nebula
57 nucleus
58 observatory9
59 photons
60 position
61 quasars
62 radio4–6
63 range
64 ray telescope10
65 ray6–8 frequencies
66 showers
67 signals
68 significance
69 source
70 source location
71 starlight
72 statistical significance
73 such photons
74 telescope10
75 uncertainty
76 schema:name Detection of TeV photons from the active galaxy Markarian 421
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