58 research outputs found
A Study of CO Emission in High Redshift QSOs Using the Owens Valley Millimeter Array
Searches for CO emission in high-redshift objects have traditionally suffered
from the accuracy of optically-derived redshifts due to lack of bandwidth in
correlators at radio observatories. This problem has motivated the creation of
the new COBRA continuum correlator, with 4 GHz available bandwidth, at the
Owens Valley Radio Observatory Millimeter Array. Presented here are the first
scientific results from COBRA. We report detections of redshifted CO(J=3-2)
emission in the QSOs SMM J04135+10277 and VCV J140955.5+562827, as well as a
probable detection in RX J0911.4+0551. At redshifts of z=2.846, z=2.585, and
z=2.796, we find integrated CO flux densities of 5.4 Jy km/s, 2.4 Jy km/s, and
2.9 Jy km/s for SMM J04135+10277, VCV J140955.5+562827, and RX J0911.4+0551,
respectively, over linewidths of Delta(V_{FWHM}) ~ 350 km/s. These
measurements, when corrected for gravitational lensing, correspond to molecular
gas masses of order M(H_2) ~ 10^{9.6-11.1} solar masses, and are consistent
with previous CO observations of high-redshift QSOs. We also report 3-sigma
upper limits on CO(3-2) emission in the QSO LBQS 0018-0220 of 1.3 Jy km/s. We
do not detect significant 3mm continuum emission from any of the QSOs, with the
exception of a tentative (3-sigma) detection in RX J0911.4+0551 of S_{3mm}=0.92
mJy/beam.Comment: 18 pages, 5 figures, 2 tables, accepted to ApJ. Changes made for
version 2: citations added, 2 objects added to Table 2 and Figure
SN1999E: Another piece in the SN-GRB connection puzzle
Detailed optical and near-IR observations of SN 1999E have confirmed early
suggestions that this supernova was indeed a twin of the peculiar type II SN
1997cy: it was exceptionally luminous and had evolved slowly, and the line
profiles had narrow peaks and broad wings, indicating interaction with the
circumstellar material. Nevertheless, the most intriguing characteristic was
that, in analogy to SN 1997cy, it exploded at a position consistent in time and
location with a BATSE event (GRB980910). The "a posteriori" probability that
the only two SNe with such an optical appearance are associated with two
different BATSE GRB is only 0.2%. This raises the possibility that some GRB are
associated with H--rich SNe.Comment: accepted for publication in MNRA
The Leo I Cloud: Secular nuclear evolution of NGC 3379, NGC 3384, and NGC 3368?
The central regions of the three brightest members of the Leo I galaxy group
-- NGC 3368, NGC 3379, and NGC 3384 -- are investigated by means of 2D
spectroscopy. In all three galaxies we have found separate circumnuclear
stellar and gaseous subsystems -- more probably, disks -- whose spatial
orientations and spins are connected to the spatial orientation of the
supergiant intergalactic HI ring reported previously by Schneider et al. (1983)
and Schneider (1985, 1989). In NGC 3368 the global gaseous disk seems also to
be inclined to the symmetry plane of the stellar body, being probably of
external origin. Although the rather young mean stellar age and spatial
orientations of the circumnuclear disks in NGC 3379, NGC 3384, and NGC 3368
could imply their recent formation from material of the intergalactic HI cloud,
the time scale of these secondary formation events, of order 3 Gyr, does not
support the collision scenario of Rood & Williams (1985), but is rather in line
with the ideas of Schneider (1985, 1989) regarding tidal interactions of the
galaxies with the HI cloud on timescales of the intergroup orbital motions.Comment: Accepted to ApJ, 46 pages (figs 18 and 22 are low resolution
Evidence of galaxy interaction in the Narrow-line Seyfert 1 galaxy IRAS17020+4544 seen by NOEMA
The narrow-line Seyfert 1 galaxy IRAS17020+4544 is one of the few sources
where both an X-ray ultra-fast outflow and a molecular outflow were observed to
be consistent with energy conservation. However, IRAS17020+4544 is less massive
and has a much more modest active galactic nucleus (AGN) luminosity than the
other examples. Using recent CO(1-0) observations with the NOrthern Extended
Millimeter Array (NOEMA), we characterised the molecular gas content of the
host galaxy for the first time. We found that the molecular gas is distributed
into an apparent central disc of 1.1x10^9 Msun, and a northern extension
located up to 8 kpc from the centre with a molecular gas mass M_H2~10^8 Msun.
The molecular gas mass and the CO dynamics in the northern extension reveal
that IRAS 17020+4544 is not a standard spiral galaxy, instead it is interacting
with a dwarf object corresponding to the northern extension. This interaction
possibly triggers the high accretion rate onto the super massive black hole.
Within the main galaxy, which hosts the AGN, a simple analytical model predicts
that the molecular gas may lie in a ring, with less molecular gas in the
nuclear region. Such distribution may be the result of the AGN activity which
removes or photodissociates the molecular gas in the nuclear region (AGN
feedback). Finally, we have detected a molecular outflow of mass
M_H2=(0.7-1.2)x10^7 Msun in projection at the location of the northern galaxy,
with a similar velocity to that of the massive outflow reported in previous
millimeter data obtained by the Large Millimeter Telescope.Comment: Published in MNRAS, Volume 501, Issue 1, Pages 219-22
Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A Thirteen-Year Study of Spectral Variability in NGC 5548
We present the final installment of an intensive 13-year study of variations
of the optical continuum and broad H-beta emission line in the Seyfert 1 galaxy
NGC 5548. The data base consists of 1530 optical continuum measurements and
1248 H-beta measurements. The H-beta variations follow the continuum variations
closely, with a typical time delay of about 20 days. However, a year-by-year
analysis shows that the magnitude of emission-line time delay is correlated
with the mean continuum flux. We argue that the data are consistent with the
simple model prediction that the size of the broad-line region is proportional
to the square root of the ionizing luminosity. Moreover, the apparently linear
nature of the correlation between the H-beta response time and the nonstellar
optical continuum arises as a consequence of the changing shape of the
continuum as it varies, specifically with the optical (5100 A) continuum
luminosity proportional to the ultraviolet (1350 A) continuum luminosity to the
0.56 power.Comment: 20 pages plus 4 figures. Accepted for publication in The
Astrophysical Journa
Early Science with the Large Millimeter Telescope: an energy-driven wind revealed by massive molecular and fast X-ray outflows in the Seyfert Galaxy IRAS 17020+4544
We report on the coexistence of powerful gas outflows observed in millimeter
and X-ray data of the Radio-Loud Narrow Line Seyfert 1 Galaxy IRAS 17020+4544.
Thanks to the large collecting power of the Large Millimeter Telescope, a
prominent line arising from the 12CO(1-0) transition was revealed in recent
observations of this source. The complex profile is composed by a narrow
double-peak line and a broad wing. While the double-peak structure may be
arising in a disk of molecular material, the broad wing is interpreted as the
signature of a massive outflow of molecular gas with an approximate bulk
velocity of -660 km/s. This molecular wind is likely associated to a
multi-component X-ray Ultra-Fast Outflow with velocities reaching up to ~0.1c
and column densities in the range 10^{21-23.9} cm^-2 that was reported in the
source prior to the LMT observations. The momentum load estimated in the two
gas phases indicates that within the observational uncertainties the outflow is
consistent with being propagating through the galaxy and sweeping up the gas
while conserving its energy. This scenario, which has been often postulated as
a viable mechanism of how AGN feedback takes place, has so far been observed
only in ULIRGs sources. IRAS 17020+4544 with bolometric and infrared luminosity
respectively of 5X10^{44} erg/s and 1.05X10^{11} L_sun appears to be an example
of AGN feedback in a NLSy1 Galaxy (a low power AGN). New proprietary
multi-wavelength data recently obtained on this source will allow us to
corroborate the proposed hypothesis.Comment: Accepted for publication on ApJ Letters, 9 pages, 4 figure
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