Magnetic flares and the observed τt ∼ 1 in seyfert galaxies

Sergei Nayakshin, Fulvio Melia

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We here consider the pressure equilibrium during an intense magnetic flare above the surface of a cold accretion disk. Under the assumption that the heating source for the plasma trapped within the flaring region is an influx of energy transported inward with a group velocity close to c, e.g., by magnetohydrodynamic waves, this pressure equilibrium can constrain the Thomson optical depth, ΤT, to be of order unity. We suggest that this may be the reason why τT ∼ 1 in Seyfert galaxies. We also consider whether current data can distinguish between the spectrum produced by a single X-ray-emitting region with τT ∼ 1 and that formed by many different flares spanning a range of τT. We find that the current observations do not yet have the required energy resolution to permit such a differentiation. Thus, it is possible that the entire X-ray/γ-ray spectrum of Seyfert galaxies is produced by many independent magnetic flares with an optical depth of 0.5 < τT < 2.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume490
Issue number1 PART II
StatePublished - 1997

Fingerprint

Seyfert galaxies
optical depth
flares
optical thickness
magnetohydrodynamics
energy
accretion
magnetohydrodynamic waves
heating
plasma
group velocity
accretion disks
unity
rays
x rays
flaring
cold

Keywords

  • Acceleration of particles
  • Agnetic fields
  • Galaxies: Seyfert
  • Lack hole physics
  • Plasmas
  • Radiation mechanisms: nonthermal

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Magnetic flares and the observed τt ∼ 1 in seyfert galaxies. / Nayakshin, Sergei; Melia, Fulvio.

In: Astrophysical Journal, Vol. 490, No. 1 PART II, 1997.

Research output: Contribution to journalArticle

@article{35df4cc67f7a4c338dd566c51b3e8cd7,
title = "Magnetic flares and the observed τt ∼ 1 in seyfert galaxies",
abstract = "We here consider the pressure equilibrium during an intense magnetic flare above the surface of a cold accretion disk. Under the assumption that the heating source for the plasma trapped within the flaring region is an influx of energy transported inward with a group velocity close to c, e.g., by magnetohydrodynamic waves, this pressure equilibrium can constrain the Thomson optical depth, ΤT, to be of order unity. We suggest that this may be the reason why τT ∼ 1 in Seyfert galaxies. We also consider whether current data can distinguish between the spectrum produced by a single X-ray-emitting region with τT ∼ 1 and that formed by many different flares spanning a range of τT. We find that the current observations do not yet have the required energy resolution to permit such a differentiation. Thus, it is possible that the entire X-ray/γ-ray spectrum of Seyfert galaxies is produced by many independent magnetic flares with an optical depth of 0.5 < τT < 2.",
keywords = "Acceleration of particles, Agnetic fields, Galaxies: Seyfert, Lack hole physics, Plasmas, Radiation mechanisms: nonthermal",
author = "Sergei Nayakshin and Fulvio Melia",
year = "1997",
language = "English (US)",
volume = "490",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 PART II",

}

TY - JOUR

T1 - Magnetic flares and the observed τt ∼ 1 in seyfert galaxies

AU - Nayakshin, Sergei

AU - Melia, Fulvio

PY - 1997

Y1 - 1997

N2 - We here consider the pressure equilibrium during an intense magnetic flare above the surface of a cold accretion disk. Under the assumption that the heating source for the plasma trapped within the flaring region is an influx of energy transported inward with a group velocity close to c, e.g., by magnetohydrodynamic waves, this pressure equilibrium can constrain the Thomson optical depth, ΤT, to be of order unity. We suggest that this may be the reason why τT ∼ 1 in Seyfert galaxies. We also consider whether current data can distinguish between the spectrum produced by a single X-ray-emitting region with τT ∼ 1 and that formed by many different flares spanning a range of τT. We find that the current observations do not yet have the required energy resolution to permit such a differentiation. Thus, it is possible that the entire X-ray/γ-ray spectrum of Seyfert galaxies is produced by many independent magnetic flares with an optical depth of 0.5 < τT < 2.

AB - We here consider the pressure equilibrium during an intense magnetic flare above the surface of a cold accretion disk. Under the assumption that the heating source for the plasma trapped within the flaring region is an influx of energy transported inward with a group velocity close to c, e.g., by magnetohydrodynamic waves, this pressure equilibrium can constrain the Thomson optical depth, ΤT, to be of order unity. We suggest that this may be the reason why τT ∼ 1 in Seyfert galaxies. We also consider whether current data can distinguish between the spectrum produced by a single X-ray-emitting region with τT ∼ 1 and that formed by many different flares spanning a range of τT. We find that the current observations do not yet have the required energy resolution to permit such a differentiation. Thus, it is possible that the entire X-ray/γ-ray spectrum of Seyfert galaxies is produced by many independent magnetic flares with an optical depth of 0.5 < τT < 2.

KW - Acceleration of particles

KW - Agnetic fields

KW - Galaxies: Seyfert

KW - Lack hole physics

KW - Plasmas

KW - Radiation mechanisms: nonthermal

UR - http://www.scopus.com/inward/record.url?scp=0006814764&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0006814764&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0006814764

VL - 490

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 PART II

ER -