Sgr A* and its siblings in nearby galaxies

نویسنده

  • Heino Falcke
چکیده

We have proposed previously that Sgr A* is simply a scaled down AGN with a black hole, an accretion disk and a radio jet operating at a very low power. It appears as if M81* { the nuclear source in the nearby galaxy M81 { is an ideal laboratory to study a Sgr A*-like source at a higher power level. The jet/disk model can explain M81* in great detail with no basic changes in the model parameters other than the accretion rate. Radio cores in other LINERs may be explained by the same model and they appear to be low-power counterparts to radio-loud quasar cores. For Sgr A*, models without a supermassive black hole are facing diiculties { some of which are discussed here, but a persistent puzzle in any scenario are the non-detecions and low ux limits for Sgr A* from IR to x-rays. Especially the IR limits are a threat to accretion models. I discuss whether a thin molecular disk (as seen in NGC 4258) around Sgr A* could intercept infalling material before it reaches the black hole.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

ar X iv : a st ro - p h / 96 04 18 5 v 1 1 M ay 1 99 6 Sgr A * and its siblings in nearby galaxies

We have proposed previously that Sgr A* is simply a scaled down AGN with a black hole, an accretion disk and a radio jet operating at a very low power. It appears as if M81* – the nuclear source in the nearby galaxy M81 – is an ideal laboratory to study a Sgr A*-like source at a higher power level. The jet/disk model can explain M81* in great detail with no basic changes in the model parameters...

متن کامل

Sgrs in Nearby Galaxies: Rate, Luminosity Function and Fraction among Short Grbs

It was suggested that some of the short-duration Gamma-Ray Bursts (GRB) are giant flares of Soft Gammaray Repeaters (SGR) in nearby galaxies. To test this hypothesis, I have constructed a sample of 47 short GRBs, detected by the Inter-Planetary Network (IPN), for which the position is constrained by at least one annulus on the celestial sphere. For each burst, I have checked whether its IPN 3-σ...

متن کامل

Soft Gamma-ray Repeaters in Nearby Galaxies: Rate, Luminosity Function, and Fraction among Short Gamma-ray Bursts

It was suggested that some of the short-duration gamma-ray bursts (GRBs) are giant flares of soft gamma-ray repeaters (SGRs) in nearby galaxies. To test this hypothesis, I have constructed a sample of 47 short GRBs, detected by the Interplanetary Network (IPN), for which the position is constrained by at least one annulus on the celestial sphere. For each burst, I have checked whether its IPN 3...

متن کامل

A Radio Census of Nuclear Activity in Nearby Galaxies

In order to determine the incidence of black hole accretion-driven nuclear activity in nearby galaxies, as manifested by their radio emission, we have carried out a high-resolution Multi-Element Radio-Linked Interferometer Network (MERLIN) survey of LINERs and composite LINER/Hii galaxies from a complete magnitude-limited sample of bright nearby galaxies (Palomar sample) with unknown arcsecond-...

متن کامل

Soft gamma repeaters outside the Local Group

We propose that the best sites to search for Soft Gamma Repeaters (SGRs) outside the Local Group are the galaxies with active massive-star formation. Different possibilities to observe SGR activity from these sites are discussed. In particular, we have searched for giant flares from the nearby galaxies (∼ 2 – 4 Mpc away) M82, M83, NGC 253, and NGC 4945 in the BATSE data. No candidate giant SGR ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2008