157 research outputs found
A Captured Runaway Black Hole in NGC 1277?
Recent results indicate that the compact lenticular galaxy NGC 1277 in the
Perseus Cluster contains a black hole of approximately 10 billion solar masses.
This far exceeds the expected mass of the central black hole in a galaxy of the
modest dimensions of NGC 1277. We suggest that this giant black hole was
ejected from the nearby giant galaxy NGC 1275 and subsequently captured by NGC
1277. The ejection was the result of gravitational radiation recoil when two
large black holes merged following the merger of two giant ellipticals that
helped to form NGC 1275. The black hole wandered in the cluster core until it
was captured in a close encounter with NGC 1277. The migration of black holes
in clusters may be a common occurrence.Comment: Four pages, accepted by The Astrophysical Journal Letters. Major
revisions, especially Section
The Black Hole Mass - Galaxy Luminosity Relationship for Sloan Digital Sky Survey Quasars
We investigate the relationship between the mass of the central supermassive
black hole, M_bh, and the host galaxy luminosity, L_gal, in a sample of quasars
from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We use composite
quasar spectra binned by black hole mass and redshift to assess galaxy features
that would otherwise be overwhelmed by noise in individual spectra. The black
hole mass is calculated using the photoionization method, and the host galaxy
luminosity is inferred from the depth of the Ca II H + K features in the
composite spectra. We evaluate the evolution in the M_bh - L_gal relationship
by examining the redshift dependence of Delta log M_bh, the offset in black
hole mass from the local black hole - bulge relationship. There is little
systematic trend in Delta log M_bh out to z = 0.8. Using the width of the [O
III] emission line as a proxy for the stellar velocity dispersion, sigma_*, we
find agreement of our derived host luminosities with the locally-observed
Faber-Jackson relation. This supports the utility of the width of the [O III]
line as a proxy for sigma_* in statistical studies.Comment: 10 pages, 5 figures; final version; major revision
Recoiling Black Holes in Quasars
Recent simulations of merging black holes with spin give recoil velocities
from gravitational radiation up to several thousand km/s. A recoiling
supermassive black hole can retain the inner part of its accretion disk,
providing fuel for a continuing QSO phase lasting millions of years as the hole
moves away from the galactic nucleus. One possible observational manifestation
of a recoiling accretion disk is in QSO emission lines shifted in velocity from
the host galaxy. We have examined QSOs from the Sloan Digital Sky Survey with
broad emission lines substantially shifted relative to the narrow lines. We
find no convincing evidence for recoiling black holes carrying accretion disks.
We place an upper limit on the incidence of recoiling black holes in QSOs of 4%
for kicks greater than 500 km/s and 0.35% for kicks greater than 1000 km/s
line-of-sight velocity.Comment: 4 pages, 4 figures, uses emulateapj, Submitted to ApJ Letter
Comment on the Black Hole Recoil Candidate Quasar SDSS J092712.65+294344.0
SDSS J092712.65+294344.0 has been proposed as a candidate for a supermassive
black hole (~10^8.8 solar masses) ejected at high speed from the host galactic
nucleus by gravitational radiation recoil, or alternatively for a supermassive
black hole binary. This is based on a blueshift of 2650 km/s of the broad
emission lines ("b-system") relative to the narrow emission lines ("r-system")
presumed to reflect the galaxy velocity. New observations with the Hobby-Eberly
Telescope (HET) confirm the essential features of the spectrum. We note a third
redshift system, characterized by weak, narrow emission lines of [O III] and [O
II] at an intermediate velocity 900 km/s redward of the broad line velocity
("i-system"). A composite spectrum of SDSS QSOs similar to J0927 illustrates
the feasibility of detecting the calcium K absorption line in spectra of
sufficient quality. The i-system may represent the QSO host galaxy or a
companion. Photoionization requires the black hole to be ~3 kpc from the
r-system emitting gas, implying that we are observing the system only 10^6 yr
after the recoil event and contributing to the low probability of observing
such a system. The HET observations give an upper limit of 10 km/s per year on
the rate of change of the velocity difference between the r- and b-systems,
constraining the orbital phase in the binary model. These considerations and
the presence of a cluster of galaxies apparently containing J0927 favor the
idea that this system represents a superposition of two AGN.Comment: 18 pages, 4 figures, ApJ in press, revised discussion of stellar
absorption features and binary black hole mode
INTEGRAL High Energy Observations of 2S 0114+65
We report the first INTEGRAL timing and spectral analysis of the high mass
X-ray binary source 2S 0114+65 at high energies (5-100 keV). The pulse period
was found at 2.668 hr with a high pulsed fraction, ~80% in both the 20-40 keV
and 40-80 keV energy bands. The spin-up trend over ~8 years was measured to be
-8.9 * 10^{-7}. The hard X-ray spectrum obtained with JEM-X/ISGRI is well
described by a high energy exponential cut-off power law model where the
estimated luminosity is 1.8 * 10^{36} erg/s in the 5-100 keV energy band, for a
source distance of 7.2 kpc. We tentatively identify a cyclotron resonance
scattering feature at ~22 keV with one harmonic, implying a magnetic field of
2.5 * 10^{12} G.Comment: 4 pages, 5 figures, accepted to A&A Letter
The Quasar SDSS J105041.35+345631.3: Black Hole Recoil or Extreme Double-Peaked Emitter?
The quasar SDSS J105041.35+345631.3 (z = 0.272) has broad emission lines
blueshifted by 3500 km/s relative to the narrow lines and the host galaxy. Such
an object may be a candidate for a recoiling supermassive black hole, binary
black hole, a superposition of two objects, or an unusual geometry for the
broad emission-line region. The absence of narrow lines at the broad line
redshift argues against superposition. New Keck spectra of J1050+3546 place
tight constraints on the binary model. The combination of large velocity shift
and symmetrical H-beta profile, as well as aspects of the narrow line spectrum,
make J1050+3546 an interesting candidate for black hole recoil. Other aspects
of the spectrum, however, suggest that the object is most likely an extreme
case of a ``double-peaked emitter.'' We discuss possible observational tests to
determine the true nature of this exceptional object.Comment: 5 pages, 2 figures, LaTeX; substantial revision
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