3,856 research outputs found
A CO Survey of Gravitationally Lensed Quasars with the IRAM Interferometer
We present the results of a CO survey of gravitationally lensed quasars,
conducted with the Plateau de Bure Interferometer over the last three years.
Among the 18 objects surveyed, one was detected in CO line emission, while six
were detected in the continuum at 3mm and three in the continuum at 1mm. The
low CO detection rate may at least in part be due to uncertainties in the
redshifts derived from quasar broad emission lines. The detected CO source, the
z=3.2 radio quiet quasar MG0751+2716, is quite strong in the CO(4-3) line and
in the millimeter/submillimeter continuum, the latter being emission from cool
dust. The integrated CO line flux is 5.96 +- 0.45 Jy.km/s, and the total
molecular gas mass is estimated to be in the range M(H_2) = 1.6-3.1 X 10^9
solar masses.Comment: 5 pages, 2 figures, uses aa.cls and psfig.st
Mafic alkaline metasomatism in the lithosphere underneath East Serbia: evidence from the study of xenoliths and the host alkali basalts
Effects of mafic alkaline metasomatism have been investigated by a combined study of the East Serbian mantle xenoliths and their host alkaline rocks. Fertile xenoliths and tiny mineral assemblages found in depleted xenoliths have been investigated. Fertile lithologies are represented by clinopyroxene (cpx)-rich lherzolite and spinel (sp)-rich olivine websterite containing Ti–Al-rich Cr-augite, Fe-rich olivine, Fe–Al-rich orthopyroxene and Al-rich spinel. Depleted xenoliths, which are the predominant lithology in the suite of East Serbian xenoliths, are harzburgite, cpx-poor lherzolite and rare Mg-rich dunite. They contain small-scale assemblages occurring as pocket-like, symplectitic or irregular, deformation-assisted accumulations of metasomatic phases, generally composed of Ti–Al- and incompatible element-rich Cr-diopside, Cr–Fe–Ti-rich spinel, altered glass, olivine, apatite, ilmenite, carbonate, feldspar, and a high-TiO2 (c. 11 wt%) phlogopite. The fertile xenoliths are too rich in Al, Ca and Fe to simply represent undepleted mantle. By contrast, their composition can be reproduced by the addition of 5–20 wt% of a basanitic melt to refractory mantle. However, textural relationships found in tiny mineral assemblages inside depleted xenoliths imply the following reaction: opx+sp1 (primary mantle Cr-spinel) ±phlogopite+Si-poor alkaline melt=Ti–Al-cpx+sp2 (metasomatic Ti-rich spinel)±ol±other minor phases. Inversion modelling, performed on the least contaminated and most isotopically uniform host basanites (87Sr/86Sr=c. 0.7031; 143Nd/144Nd=c. 0.5129), implies a source that was enriched in highly and moderately incompatible elements (c. 35–40× chondrite for U–Th–Nb–Ta, 2× chondrite for heavy rare earth elements (HREE), made up of clinopyroxene, carbonate (c. 5%), and traces of ilmenite (c. 1%) and apatite (c. 0.05%). A schematic model involves: first, percolation of CO2- and H2O-rich fluids and precipitation of metasomatic hydrous minerals; and, second, the subsequent breakdown of these hydrous minerals due to the further uplift of hot asthenospheric mantle. This model links intraplate alkaline magmatism to lithospheric mantle sources enriched by sublithospheric melts at some time in the past
First redshift determination of an optically/UV faint submillimeter galaxy using CO emission lines
We report the redshift of a distant, highly obscured submm galaxy (SMG),
based entirely on the detection of its CO line emission. We have used the newly
commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8
GHz of instantaneous dual-polarization bandwidth, to search the 3-mm
atmospheric window for CO emission from SMMJ14009+0252, a bright SMG detected
in the SCUBA Lens Survey. A detection of the CO(3--2) line in the 3-mm window
was confirmed via observations of CO(5--4) in the 2-mm window. Both lines
constrain the redshift of SMMJ14009+0252 to z=2.9344, with high precision (dz=2
10^{-4}). Such observations will become routine in determining redshifts in the
era of the Atacama Large Millimeter/submillimeter Array (ALMA).Comment: 5 pages, 3 figures, accepted by ApJ
Dense Molecular Gas and the Role of Star Formation in the Host Galaxies of Quasi-Stellar Objects
New millimeter-wave CO and HCN observations of the host galaxies of
infrared-excess Palomar Green quasi-stellar objects (PG QSOs) previously
detected in CO are presented. These observations are designed to assess the
validity of using the infrared luminosity to estimate star formation rates of
luminous AGN by determining the relative significance of dust-heating by young,
massive stars and active galactic nuclei (AGN) in QSO hosts and IRAS galaxies
with warm, AGN-like infrared colors. The HCN data show the PG QSO host IZw1 and
most of the warm IRAS galaxies to have high L_IR / L'_HCN (>1600) relative to
the cool IRAS galaxy population for which the median L_IR / L'_HCN ~
890(+440,-470). If the assumption is made that the infrared emission from cool
IRAS galaxies is reprocessed light from embedded star-forming regions, then
high values of L_IR / L'_HCN are likely the result of dust heating by the AGN.
Further, if the median ratio of L'_HCN / L'_CO ~ 0.06 observed for Seyfert
galaxies and IZw1 is applied to the PG QSOs not detected in HCN, then the
derived L_IR / L'_HCN correspond to a stellar contribution to the production of
L_IR of ~ 7-39%, and star formation rates ~ 2-37 M_sun/yr are derived for the
QSO hosts. Alternatively, if the far-infrared is adopted as the star formation
component of the total infrared in cool galaxies, the stellar contributions in
QSO hosts to their L_FIR are up to 35% higher than the percentages derived for
L_IR. This raises the possibility that the L_FIR in several of the PG QSO
hosts, including IZw1, could be due entirely to dust heated by young, massive
stars. Finally, there is no evidence that the global HCN emission is enhanced
relative to CO in galaxies hosting luminous AGN.Comment: LaTex, 31 pages, including 9 postscript figures, AJ, in press
(December 2006
Quantum Connectivity of Space-Time and Gravitationally Induced Decorrelation of Entanglement
We discuss an alternative formulation of the problem of quantum optical
fields in a curved space-time using localized operators. We contrast the new
formulation with the standard approach and find observable differences for
entangled states. We propose an experiment in which an entangled pair of
optical pulses are propagated through non-uniform gravitational fields and find
that the new formulation predicts de-correlation of the optical entanglement
under experimentally realistic conditions
The quasar Q0957+561: Lensed CO emission from a disk at z~1.4?
In recent years large efforts have been made to detect molecular gas towards
high redshifted objects. Up to now the literature reports on only two cases of
CO-detection in quasars at a redshift between 1 and 2 - Q0957+561, a
gravitationally lensed system at z=1.41 (Planesas et al. 1999), and HR10 at
z=1.44 (Andreani et al. 2000). According to Planesas et al. (1999), 12CO(2-1)
emission was detected towards both the lensed images of Q0957+561 with the IRAM
Plateau de Bure Interferometer (PdBI). In contrast to the optical spectra of
the two images which support the idea that they are images of one and the same
object, the CO-spectra were surprisingly different: the southern image (named
CO-B) shows a single blueshifted line whereas a double-peaked line profile with
a blue- and a redshifted part appears towards the northern image (CO-A). Based
on the observations and on simulations with a gravitational lens program, we
are tempted to argue that the line profile traces the presence of molecular gas
of a disk in the host galaxy around the quasar. We have now new observations
with the PdBI providing the necessary sensitivity to corroborate our disk
model.Comment: 4 pages, 1 figure, to appear in "Proceedings of the 4th
Cologne-Bonn-Zermatt-Symposium", ed. S. Pfalzner, C. Kramer, C. Straubmeier,
and A. Heithausen (Springer Verlag
Infrared and radio observations of W51: Another Orion-KL at a distance of 7kpc
The bright infrared sources W51-IRS2 has at least three components with different physical and evolutionary properties. The spatial distribution and the near infrared spectra of the components in IRS2 are remarkably similar to, but more luminous than those found in Orion, where an H2 region of comparable linear size is also located close to a cluster of compact infrared sources. The characteristics of the nearby W51-NORTH H2O maser source, and the detection of 2 micro m H2 quadrupole emission in IRS2 indicate that the mass loss phenomena found in Orion-KL also exist in W51
The faint counterparts of MAMBO mm sources near the NTT Deep Field
We discuss identifications for 18 sources from our MAMBO 1.2mm survey of the
region surrounding the NTT Deep Field. We have obtained accurate positions from
Very Large Array 1.4GHz interferometry and in a few cases IRAM mm
interferometry, and have also made deep BVRIzJK imaging at ESO. We find
thirteen 1.2mm sources associated with optical/near-infrared objects in the
magnitude range K=19.0 to 22.5, while five are blank fields at K>22. The median
redshift of the radio-identified mm sources is ~2.6 from the radio/mm
estimator, and the median optical/near-infrared photometric redshifts for the
objects with counterparts ~2.1. This suggests that those radio-identified mm
sources without optical/near-infrared counterparts tend to lie at higher
redshifts than those with optical/near-infrared counterparts. Compared to
published identifications of objects from 850micron surveys of similar depth,
the median K and I magnitudes of our counterparts are roughly two magnitudes
fainter and the dispersion of I-K colors is less. Real differences in the
median redshifts, residual mis-identifications with bright objects, cosmic
variance, and small number statistics are likely to contribute to this
significant difference, which also affects redshift measurement strategies. We
discuss basic properties of the near-infrared/(sub)mm/radio spectral energy
distributions of our galaxies and of interferometrically identified submm
sources from the literature. From a comparison with submm objects with
CO-confirmed spectroscopic redshifts we argue that roughly two thirds of the
(sub)mm galaxies are at z>~2.5. This fraction is probably larger when including
sources without radio counterparts. (abridged)Comment: 45 pages, 9 figures. Accepted by ApJ. The resolution of figures 2 and
3 has been degraded. A higher quality pdf version of this paper is available
at http://www.mpe.mpg.de/~dannerb
New Observations and a New Interpretation of CO(3--2) in IRAS F10214+4724
New observations with the IRAM interferometer of CO(3--2) from the highly
luminous galaxy IRAS F10214+4724 show the source is 1.5'' x <= 0.9'' ; they
display no evidence of any velocity gradient. This size, together with optical
and IR data that show the galaxy is probably gravitationally lensed, lead to a
new model for the CO distribution. In contrast to many lensed objects, we have
a good estimate of the intrinsic CO and far IR surface brightnesses, so we can
derive the CO and far IR/sub-mm magnifications. The CO is magnified 10 times
and has a true radius of 400 pc. and the far IR is magnified 13 times and has a
radius of 250 pc. The true far IR luminosity is 4 to 7e12 Lsun and the
molecular gas mass is 2e10 Msun . This is nearly an order of magnitude less
than previously estimated. Because the far IR magnification is lower than the
mid and near IR magnification, the intrinsic spectral energy distribution now
peaks in the far infrared. That is, nearly all of the energy of this object is
absorbed and re-emitted in the far infrared. In CO luminosity, molecular gas
content, CO linewidth, and corrected far IR luminosity, 10214+472 is a typical,
warm, IR ultraluminous galaxy.Comment: 18 pages, including 3 figures, of gzipped, uuencoded postscript. To
be published Ap.J. Letter
The Stellar Populations and Evolution of Lyman Break Galaxies
Using deep near-IR and optical observations of the HDF-N from the HST NICMOS
and WFPC2 and from the ground, we examine the spectral energy distributions
(SEDs) of Lyman break galaxies (LBGs) at 2.0 < z < 3.5. The UV-to-optical
rest-frame SEDs of the galaxies are much bluer than those of present-day spiral
and elliptical galaxies, and are generally similar to those of local starburst
galaxies with modest amounts of reddening. We use stellar population synthesis
models to study the properties of the stars that dominate the light from LBGs.
Under the assumption that the star-formation rate is continuous or decreasing
with time, the best-fitting models provide a lower bound on the LBG mass
estimates. LBGs with ``L*'' UV luminosities are estimated to have minimum
stellar masses ~ 10^10 solar masses, or roughly 1/10th that of a present-day L*
galaxy. By considering the effects of a second component of maximally-old
stars, we set an upper bound on the stellar masses that is ~ 3-8 times the
minimum estimate. We find only loose constraints on the individual galaxy ages,
extinction, metallicities, initial mass functions, and prior star-formation
histories. We find no galaxies whose SEDs are consistent with young (< 10^8
yr), dust-free objects, which suggests that LBGs are not dominated by ``first
generation'' stars, and that such objects are rare at these redshifts. We also
find that the typical ages for the observed star-formation events are
significantly younger than the time interval covered by this redshift range (~
1.5 Gyr). From this, and from the relative absence of candidates for quiescent,
non-star-forming galaxies at these redshifts in the NICMOS data, we suggest
that star formation in LBGs may be recurrent, with short duty cycles and a
timescale between star-formation events of < 1 Gyr. [Abridged]Comment: LaTeX, 37 pages, 21 figures. Accepted for publication in the
Astrophysical Journa
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