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Cited by 183Astrophysical Phenomena and ObservationsAstrophysics and Cosmic PhenomenaGalaxies: Formation, Evolution, Phenomena

On the Nature of the Variable Infrared Emission from Sagittarius A*

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Yuan, Feng, Quataert, Eliot, Narayan, Ramesh·2004·The Astrophysical Journal
DOI 10.1086/383117
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Abstract

Recent infrared (IR) observations of the center of our Galaxy indicate that the supermassive black hole (SMBH) source Sgr A* is strongly variable in the IR. The timescale for the variability, ~30 minutes, is comparable to that of the X-ray flares observed by Chandra and XMM-Newton , suggesting a common physical origin. In this paper, we investigate the nature of the IR emission in the context of models recently proposed to interpret the X-ray flares. We show that the IR emission in Sgr A* can be well explained by nonthermal synchrotron emission if a small fraction of the electrons in the innermost region of the accretion flow around the black hole are accelerated into a broken power-law distribution, perhaps through transient events such as magnetic reconnection. The model predicts differences in the variability amplitudes of flares in the IR and X-rays, in general agreement with observations. It also predicts that the IR emission should be linearly polarized, as has indeed been observed during one epoch. IR and X-ray flares analogous to those observed in Sgr A* may be detectable from other accreting SMBHs, provided L ≲ 10 -8 L Edd ; at higher luminosities, the flaring emission is dominated by thermal synchrotron self-Compton emission, which is likely to be less variable.

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Crossref · 10.1086/383117

Cites

49 of 49 references verified0 citation errors · 0 not checkable

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  • Different theoretical models for the accretion flow produce an accretion rate in the range of 10^-9-10^-8 M⊙/yr.

    “Different theoretical models for the accretion flow 9 produce an accretion rate in the range of 10 -9 -10 -8 M ⊙ yr -1 (Agol 2000; Quataert & Gruzinov 2000; Yuan et al. 2004; Marrone et al. 2007; Sharma et al. 2007).”

    From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Yuan et al. 2004

    Section 2, “RIAF Models for Sgr A*” (page unavailable), describes an accretion-flow model in which the rate varies with radius and is suppressed near the black hole. It does not give the claimed range of 10^-9–10^-8 solar masses per year; searches for those values and their units found no matching passage. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

  • The current accretion rate in the Milky Way is approximately 10^-8 solar masses per year.

    “Since the current accretion rate in our galaxy is ∼ 10 -8 M ⊙ yr -1 (Yuan et al. 2004), ˙ M acc / ˙ M edd ∼ 10 -7 .”

    From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Yuan et al. 2004

    Section 2 (page unavailable) models the accretion rate onto the central black hole but gives no value in solar masses per year. I searched the indexed copy for 10^-8 solar masses per year and equivalent notation; the 10^-8 figure in Section 4 refers to luminosity in Eddington units, not an accretion rate. (LLM, conf=0.72)

    Experimental — accuracy not yet measured

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Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Baganoff, F. K. 2004, in The Central 300 Parsecs of the Milky Way (Astron. Nachr. Special Suppl., S1), in press
  2. Narayan, R. 2002, in Lighthouses of the Universe, ed. M. Gilfanov, R. Sunyaev, & E. Churazov (New York: Springer), 405
  3. ---. 2004, in The Central 300 Parsecs of the Milky Way (Astron. Nachr. Special Suppl., S1), in press (astro-ph/0304099) · arXiv
  4. Stolovy, S. R., McCarthy, D. W., Melia, F., Rieke, G., Rieke, M. J., & Yusef- Zadeh, F. 1999, in ASP Conf. Ser. 186, The Central Parsecs of the Galaxy, ed. H. Falcke et al. (San Francisco: ASP), 39
  5. Vink, J. 2003, Adv. Space Res., in press (astro-ph/0304176) · arXiv

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Related

Authors
Yuan, F., Quataert, E., & Narayan, R.
Affiliations
  • Purdue University West Lafayette (US)
  • University of California, Berkeley (US)
  • Harvard University (US)
ORCID
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2004-05-10
Volume
606
Issue
2
Pages
894-899
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.1086/383117
OpenAlex
W2034124152
Cited by
183
References
49
Citations by year
2026: 3 · 2025: 4 · 2024: 5 · 2023: 3 · 2022: 5 · 2021: 3 · 2020: 9 · 2019: 5 · 2018: 4 · 2017: 9 · 2016: 6 · 2015: 11 · 2014: 8 · 2013: 8 · 2012: 14
FWCI
8.46
Type
journal article
Language
en
Open access
Locations
  • The Astrophysical Journal (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • Digital Access to Scholarship at Harvard (DASH) (Harvard University) (submittedVersion, cc-by)
  • CERN Document Server (European Organization for Nuclear Research) (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
  • Physical Sciences › Physics and Astronomy › Nuclear and High Energy Physics › Astrophysics and Cosmic Phenomena
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
Keywords
Sgr A*, supermassive black holes, infrared variability, X-ray flares, synchrotron radiation, magnetic reconnection, accretion flow, synchrotron self-Compton, linear polarization, Galactic Center, low-luminosity active galactic nuclei

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