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Your search keyword '"Blandford, R. D."' showing total 11 results
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11 results on '"Blandford, R. D."'

1. Light bending and X-ray echoes from behind a supermassive black hole

Author

Wilkins, D. R., Gallo, L. C., Costantini, E., Brandt, W. N., and Blandford, R. D.

Subjects
Black holes (Astronomy) -- Observations -- Natural history, Light -- Observations, X-rays -- Observations, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

The innermost regions of accretion disks around black holes are strongly irradiated by X-rays that are emitted from a highly variable, compact corona, in the immediate vicinity of the black hole.sup.1-3. The X-rays that are seen reflected from the disk.sup.4, and the time delays, as variations in the X-ray emission echo or 'reverberate' off the disk.sup.5,6, provide a view of the environment just outside the event horizon. I Zwicky 1 (I Zw 1) is a nearby narrow-line Seyfert 1 galaxy.sup.7,8. Previous studies of the reverberation of X-rays from its accretion disk revealed that the corona is composed of two components: an extended, slowly varying component extending over the surface of the inner accretion disk, and a collimated core, with luminosity fluctuations propagating upwards from its base, which dominates the more rapid variability.sup.9,10. Here we report observations of X-ray flares emitted from around the supermassive black hole in I Zw 1. X-ray reflection from the accretion disk is detected through a relativistically broadened iron K line and Compton hump in the X-ray emission spectrum. Analysis of the X-ray flares reveals short flashes of photons consistent with the re-emergence of emission from behind the black hole. The energy shifts of these photons identify their origins from different parts of the disk.sup.11,12. These are photons that reverberate off the far side of the disk, and are bent around the black hole and magnified by the strong gravitational field. Observing photons bent around the black hole confirms a key prediction of general relativity. One of the key predictions of general relativity, the bending of light around massive, compact objects, is observed for a supermassive black hole in the galaxy I Zwicky 1., Author(s): D. R. Wilkins [sup.1] , L. C. Gallo [sup.2] , E. Costantini [sup.3] [sup.4] , W. N. Brandt [sup.5] [sup.6] [sup.7] , R. D. Blandford [sup.1] Author Affiliations: (1) [...]

Published
2021
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2. A change in the optical polarization associated with a γ-ray flare in the blazar 3C 279

Author

Abdo, A. A., Ackermann, M., Ajello, M., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Baughman, B. M., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bock, D. C.-J., Bogart, J. R., Bonamente, E., Borgland, A. W., Bouvier, A., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Burnett, T. H., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Casandjian, J. M., Cavazzuti, E., Cecchi, C., Çelik, Ö., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cohen-Tanugi, J., Collmar, W., Cominsky, L. R., Conrad, J., Corbel, S., Corbet, R., Costamante, L., Cutini, S., Dermer, C. D., de Angelis, A., de Palma, F., Digel, S. W., do Couto e Silva, E., Drell, P. S., Dubois, R., Dumora, D., Farnier, C., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Fortin, P., Frailis, M., Fuhrmann, L., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giebels, B., Giglietto, N., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Grove, J. E., Guillemot, L., Guiriec, S., Hanabata, Y., Harding, A. K., Hayashida, M., Hays, E., Horan, D., Hughes, R. E., Iafrate, G., Itoh, R., Jackson, M. S., Jóhannesson, G., Johnson, A. S., Johnson, W. N., Kadler, M., Kamae, T., Katagiri, H., Kataoka, J., Kawai, N., Kerr, M., Knödlseder, J., Kocian, M. L., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lemoine-Goumard, M., Longo, F., Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Macquart, J., Madejski, G. M., Makeev, A., Max-Moerbeck, W., Mazziotta, M. N., McConville, W., McEnery, J. E., McGlynn, S., Meurer, C., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Nestoras, I., Nolan, P. L., Norris, J. P., Nuss, E., Ohsugi, T., Okumura, A., Omodei, N., Orlando, E., Ormes, J. F., Paneque, D., Panetta, J. H., Parent, D., Pavlidou, V., Pearson, T. J., Pelassa, V., Pepe, M., Pesce-Rollins, M., Piron, F., Porter, T. A., Rainò, S., Rando, R., Razzano, M., Readhead, A., Reimer, A., Reimer, O., Reposeur, T., Reyes, L. C., Richards, J. L., Rochester, L. S., Rodriguez, A. Y., Roth, M., Ryde, F., Sadrozinski, H. F.-W., Sanchez, D., Sander, A., Saz Parkinson, P. M., Scargle, J. D., Sgrò, C., Shaw, M. S., Shrader, C., Siskind, E. J., Smith, D. A., Smith, P. D., Spandre, G., Spinelli, P., Stawarz, L., Stevenson, M., Strickman, M. S., Suson, D. J., Tajima, H., Takahashi, H., Takahashi, T., Tanaka, T., Taylor, G. B., Thayer, J. B., Thayer, J. G., Thompson, D. J., Tibaldo, L., Torres, D. F., Tosti, G., Tramacere, A., Uchiyama, Y., Usher, T. L., Vasileiou, V., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Wehrle, A. E., Winer, B. L., Wood, K. S., Ylinen, T., Zensus, J. A., Ziegler, M., Uemura, M., Ikejiri, Y., Kawabata, K. S., Kino, M., Sakimoto, K., Sasada, M., Sato, S., Yamanaka, M., Villata, M., Raiteri, C. M., Agudo, I., Aller, H. D., Aller, M. F., Angelakis, E., Arkharov, A. A., Bach, U., Benítez, E., Berdyugin, A., Blinov, D. A., Boettcher, M., Buemi, C. S., Chen, W. P., Dolci, M., Dultzin, D., Efimova, N. V., Gurwell, M. A., Gusbar, C., Gómez, J. L., Heidt, J., Hiriart, D., Hovatta, T., Jorstad, S. G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Lahteenmaki, A., Larionov, V. M., Larionova, E. G., Leto, P., Lin, H. C., Lindfors, E., Marscher, A. P., McHardy, I. M., Melnichuk, D. A., Mommert, M., Nilsson, K., Di Paola, A., Reinthal, R., Richter, G. M., Roca-Sogorb, M., Roustazadeh, P., Sigua, L. A., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., Umana, G., Villforth, C., Grainge, K., Moderski, R., Nalewajko, K., and Sikora, M.

Published
2010
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3. Trail of the Crab progenitor star

Author

Blandford, R. D, Kennel, C. F, Mckee, C. F, and Ostriker, J. P

Subjects
Astrophysics
Abstract

It is proposed that the jet which has been observed protruding from the northern rim of the Crab Nebula is a tubular trail of material lost by the presupernova star during its red giant phase. The movement of the red giant's stellar wind is analyzed to show that the mass profile downstream should be concentrated within a narrow cylinder. The parameters of the tube predicted by this model are presented and an observational test of the model based on the hydrogen-to-helium abundance ratio in the jet and in the Nebula as a whole is suggested; the model predicts that the ratio in the jet should be larger.

Published
1983
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6. Ion-supported tori and the origin of radio jets

Author

Rees, M. J., Begelman, M. C., Blandford, R. D., and Phinney, E. S.

Abstract

While apparently supplying tremendous power to their extended radio-emitting regions, the nuclei of most radio galaxies emit little detectable radiation. It is proposed that at the centre of each is a spinning black hole surrounded by a torus of gas too hot and tenuous to radiate efficiently. The torus anchors magnetic fields which extract rotational energy from the hole in the form of two collimated beams of relativistic particles and fields. These in turn drive the observed radio jets and hot spots. A large supply of accreting gas is thus unnecessary and radio galaxies may be interpreted as starved quasars.

Published
1982
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7. Super-luminal expansion in extragalactic radio sources

Author

Blandford, R. D., McKee, C. F., and Rees, M. J.

Abstract

Very long baseline (VLB) investigations of compact extragalactic radio sources can often be interpreted in terms of two non-thermal components apparently separating with speeds in excess of the speed of light. Given the conventional physical laws and the cosmological interpretation of large redshifts, the available morphological evidence, while inconclusive, is most compatible with a general class of models in which a signal propagating with a speed close to that of light is scattered by an appropriately shaped screen. Possible observations are discussed which might discriminate between this and alternative explanations.

Published
1977
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