Radio-loud flares from microquasars and radio-loudness of quasars
The low-frequency power spectra of the X-ray and radio emission from four microquasars suggest that two distinct modes of energy output are at work: (i) the `coupled' mode in which the X-ray and radio luminosities are closely coupled and vary only weakly, and (ii) the `flaring' mode, which...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
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2005
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| _version_ | 1797055279690416128 |
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| author | Nipoti, C Blundell, K Binney, J |
| author_facet | Nipoti, C Blundell, K Binney, J |
| author_sort | Nipoti, C |
| collection | OXFORD |
| description | The low-frequency power spectra of the X-ray and radio emission from four microquasars suggest that two distinct modes of energy output are at work: (i) the `coupled' mode in which the X-ray and radio luminosities are closely coupled and vary only weakly, and (ii) the `flaring' mode, which dramatically boosts the radio luminosity but makes no impact on the X-ray luminosity. The systems are in the flaring mode only a few percent of the time. However, flares completely dominate the power spectrum of radio emission, with the consequence that sources in which the flaring mode occurs, such as GRS 1915+105 and Cyg X-3, have radio power spectra that lie more than an order of magnitude above the corresponding X-ray power spectra. Of the four microquasars for which we have examined data, in only one, Cyg X-1, is the flaring mode seemingly inactive. While Cyg X-1 is a black-hole candidate, one of the three flaring sources, Sco X-1, is a neutron star. Consequently, it is likely that both modes are driven by the accretion disk rather than black-hole spin. Radio imaging strongly suggests that the flaring mode involves relativistic jets. A typical microquasar is in the flaring mode a few percent of the time, which is similar to the fraction of quasars that are radio loud. Thus there may be no essential difference between radio-loud and radio-quiet quasars; radio loudness may simply be a function of the epoch at which the source is observed. |
| first_indexed | 2024-03-06T19:08:25Z |
| format | Journal article |
| id | oxford-uuid:15f08485-088e-439f-8712-6206f3ea10f2 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T19:08:25Z |
| publishDate | 2005 |
| record_format | dspace |
| spelling | oxford-uuid:15f08485-088e-439f-8712-6206f3ea10f22022-03-26T10:28:20ZRadio-loud flares from microquasars and radio-loudness of quasarsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:15f08485-088e-439f-8712-6206f3ea10f2EnglishSymplectic Elements at Oxford2005Nipoti, CBlundell, KBinney, JThe low-frequency power spectra of the X-ray and radio emission from four microquasars suggest that two distinct modes of energy output are at work: (i) the `coupled' mode in which the X-ray and radio luminosities are closely coupled and vary only weakly, and (ii) the `flaring' mode, which dramatically boosts the radio luminosity but makes no impact on the X-ray luminosity. The systems are in the flaring mode only a few percent of the time. However, flares completely dominate the power spectrum of radio emission, with the consequence that sources in which the flaring mode occurs, such as GRS 1915+105 and Cyg X-3, have radio power spectra that lie more than an order of magnitude above the corresponding X-ray power spectra. Of the four microquasars for which we have examined data, in only one, Cyg X-1, is the flaring mode seemingly inactive. While Cyg X-1 is a black-hole candidate, one of the three flaring sources, Sco X-1, is a neutron star. Consequently, it is likely that both modes are driven by the accretion disk rather than black-hole spin. Radio imaging strongly suggests that the flaring mode involves relativistic jets. A typical microquasar is in the flaring mode a few percent of the time, which is similar to the fraction of quasars that are radio loud. Thus there may be no essential difference between radio-loud and radio-quiet quasars; radio loudness may simply be a function of the epoch at which the source is observed. |
| spellingShingle | Nipoti, C Blundell, K Binney, J Radio-loud flares from microquasars and radio-loudness of quasars |
| title | Radio-loud flares from microquasars and radio-loudness of quasars |
| title_full | Radio-loud flares from microquasars and radio-loudness of quasars |
| title_fullStr | Radio-loud flares from microquasars and radio-loudness of quasars |
| title_full_unstemmed | Radio-loud flares from microquasars and radio-loudness of quasars |
| title_short | Radio-loud flares from microquasars and radio-loudness of quasars |
| title_sort | radio loud flares from microquasars and radio loudness of quasars |
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