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Ran Wang,
Jeff Wagg, Chris L. Carilli,
Fabian Walter,
Lindley Lentati,
Xiaohui Fan,
Dominik A. Riechers,
Frank Bertoldi,
Desika Narayanan,
Michael A. Strauss,
Pierre Cox,
Alain Omont,
Karl M. Menten,
Kirsten K. Knudsen,
Roberto Neri,
Linhua Jiang
[show abstract]
[hide abstract]
ABSTRACT: We present ALMA observations of the [C II] 158 micron fine structure line and
dust continuum emission from the host galaxies of five redshift 6 quasars. We
also report complementary observations of 250 GHz dust continuum and CO (6-5)
line emission from the z=6.00 quasar SDSS J231038.88+185519.7. The ALMA
observations were carried out in the extended array at 0.7" resolution. We have
detected the line and dust continuum in all five objects. The derived [C II]
line luminosities are 1.6x10^{9} to 8.8x10^{9} Lsun and the [C II]-to-FIR
luminosity ratios are 3.0-5.6x10^{-4}, which is comparable to the values found
in other high-redshift quasar-starburst systems and local ultra-luminous
infrared galaxies. The sources are marginally resolved and the intrinsic source
sizes (major axis FWHM) are constrained to be 0.3" to 0.6" (i.e., 1.7 to 3.5
kpc) for the [C II] line emission and 0.2" to 0.4" (i.e., 1.2 to 2.3 kpc) for
the continuum. These measurements indicate that there is vigorous star
formation over the central few kpc in the quasar host galaxies. The ALMA
observations also constrain the dynamical properties of the atomic gas in the
starburst nuclei. The intensity-weighted velocity maps of three sources show
clear velocity gradients. Such velocity gradients are consistent with a
rotating, gravitationally bound gas component, although they are not uniquely
interpreted as such. Under the simplifying assumption of rotation, the implied
dynamical masses within the [C II]-emitting regions are of order 10^{10} to
10^{11} Msun. Given these estimates, the mass ratios between the SMBHs and the
spheroidal bulge are an order of magnitude higher than the mean value found in
local spheroidal galaxies, which is in agreement with results from previous CO
observations of high redshift quasars.
02/2013;
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[show abstract]
[hide abstract]
ABSTRACT: We report on a measurement of the temperature of the cosmic microwave
background radiation field, T_CMB, at z = 0.88582 by imaging HC3N (3-2) and
(5-4) absorption in the foreground galaxy of the gravitationally lens magnified
radio source PKS 1830-211 using the Very Long Baseline Array and the phased
Very Large Array. Low-resolution imaging of the data yields a value of Trot =
5.6+2.5-0.9 K, for the rotational temperature, Trot, which is consistent with
the temperature of the cosmic microwave background at the absorber's redshift
of 2.73(1+z) K. However, our high-resolution imaging reveals that the
absorption peak position of the foreground gas is offset from the continuum
peak position of the synchrotron radiation from PKS 1830-211 SW, which
indicates that the absorbing cloud is covering only part of the emission from
PKS 1830-211, rather than the entire core-jet region. This changes the
line-to-continuum ratios, and we find Trot between 1.1 and 2.5 K, which is
lower than the expected value. This shows that previous, Trot, measurements
could be biased due to unresolved structure.
12/2012;
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Ran Wang,
Jeff Wagg, Chris L. Carilli,
Fabian Walter,
Xiaohui Fan,
Frank Bertoldi,
Dominik. A. Riechers,
Alain Omont,
Karl M. Menten,
Pierre Cox,
Michael A. Strauss,
Desika Narayanan
[show abstract]
[hide abstract]
ABSTRACT: We have been carrying out a systematic survey of the star formation and ISM
properties in the host galaxies of z~6 quasars. Our 250 GHz observations,
together with available data from the literature, yield a sample of 14 z~6
quasars that are bright in millimeter dust continuum emission with estimated
FIR luminosities of a few 10^12 to 10^13 Lsun. Most of these
millimeter-detected z~6 quasars have also been detected in molecular CO line
emission, indicating molecular gas masses on order of 10^10 Msun. We have
searched for [C II] 158 micron fine structure line emission toward four of the
millimeter bright z~6 quasars with ALMA and all of them have been detected. All
these results suggest massive star formation at rates of about 600 to 2000
Msun/yr over the central few kpc region of these quasar host galaxies.
09/2012;
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Roberto Decarli,
Fabian Walter,
Yujin Yang, Chris L. Carilli,
Xiahoui Fan,
Joseph F. Hennawi,
Jaron Kurk,
Dominik Riechers,
Hans-Walter Rix,
Michael A. Strauss,
Bram P. Venemans
[show abstract]
[hide abstract]
ABSTRACT: We search for extended Ly-alpha emission around two z>6 quasars, SDSS
J1030+0524 (z=6.309) and SDSS J1148+5251 (z=6.419) using WFC3 narrow-band
filters on board the Hubble Space Telescope. For each quasar, we collected two
deep, narrow-band images, one sampling the Ly-alpha line+continuum at the
quasar redshifts and one of the continuum emission redwards of the line. After
carefully modeling the Point Spread Function, we find no evidence for extended
Ly-alpha emission. These observations set 2-sigma limits of L(Ly-alpha,
extended) < 3.2 x 10^{44} erg/s for J1030+0524 and L(Ly-alpha, extended) < 2.5
x 10^{44} erg/s for J1148+5251. Given the star formation rates typically
inferred from (rest-frame) far-infrared measurements of z~6 quasars, these
limits are well below the intrinsic bright Ly-alpha emission expected from the
recombination of gas photoionized by the quasars or by the star formation in
the host galaxies, and point towards significant Ly-alpha suppression or dust
attenuation. However, small extinction values have been observed along the line
of sight to the nuclei, thus reddening has to be coupled with other mechanisms
for Ly-alpha suppression (e.g., resonance scattering). No Ly-alpha emitting
companions are found, down to a 5-sigma sensitivity of ~ 1 x 10^{-17}
erg/s/cm^2/arcsec^2 (surface brightness) and ~ 5 x 10^{-17} erg/s/cm^2
(assuming point sources).
07/2012;
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[show abstract]
[hide abstract]
ABSTRACT: We present high-resolution imaging of the low-order (J = 1 and 2) CO line emission from the z = 3.93 submillimeter galaxy (SMG) MM18423+5938 using the Expanded Very Large Array, and optical and near-IR imaging using the Canada-France-Hawaii Telescope. This SMG with a spectroscopic redshift was thought to be gravitationally lensed given its enormous apparent brightness. We find that the CO emission is consistent with a complete Einstein ring with a major axis diameter of ~14, indicative of lensing. We have also identified the lensing galaxy as a very red elliptical coincident with the geometric center of the ring and estimated its photometric redshift z ~ 1.1. A first estimate of the lens magnification factor is m ~ 12. The luminosity L'CO(1 – 0) of the CO(1-0) emission is 2.71 ± 0.38 × 1011 m –1 K km s–1 pc2, and, adopting the commonly used conversion factor for ultraluminous infrared galaxies (ULIRGs), the molecular gas mass is M(H2) = 2.2 × 1011 m –1 M ☉, comparable to unlensed SMGs if corrected by m ~ 12. Our revised estimate of the far-IR luminosity of MM18423+5938 is 2 × 1013 m –1 < L FIR < 3 × 1014 m –1 L ☉, comparable to that of ULIRGs. Further observations are required to quantify the star formation rate in MM18423+5938 and to constrain the mass model of the lens in more detail.
The Astrophysical Journal Letters 08/2011; 739(1):L30. · 5.53 Impact Factor
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Ran Wang,
Jeff Wagg, Chris L. Carilli,
Roberto Neri,
Fabian Walter,
Alain Omont,
Dominik A. Riechers,
Frank Bertoldi,
Karl M. Menten,
Pierre Cox,
Michael A. Strauss,
Xiaohui Fan,
and Linhua Jiang
[show abstract]
[hide abstract]
ABSTRACT: We present new millimeter and radio observations of nine z ~ 6 quasars discovered in deep optical and near-infrared surveys. We observed the 250 GHz continuum in eight of the nine objects and detected three of them. New 1.4 GHz radio continuum data have been obtained for four sources, and one has been detected. We searched for molecular CO (6-5) line emission in the three 250 GHz detections and detected two of them. Combined with previous millimeter and radio observations, we study the far-infrared (FIR) and radio emission and quasar-host galaxy evolution with a sample of 18 z ~ 6 quasars that are faint at UV and optical wavelengths (rest-frame 1450 Å magnitudes of m 1450 ≥ 20.2). The average FIR-to-active galactic nucleus (AGN) UV luminosity ratio of this faint quasar sample is about two times higher than that of the bright quasars at z ~ 6 (m 1450 < 20.2). A fit to the average FIR and AGN bolometric luminosities of both the UV/optically faint and bright z ~ 6 quasars, and the average luminosities of samples of submillimeter/millimeter-observed quasars at z ~ 2-5, yields a relationship of L FIR ~ L bol 0.62. Five of the 18 faint z ~ 6 quasars have been detected at 250 GHz. These 250 GHz detections, as well as most of the millimeter-detected optically bright z ~ 6 quasars, follow a shallower trend of L FIR ~ L bol 0.45 defined by the starburst-AGN systems in local and high-z universe. The millimeter continuum detections in the five objects and molecular CO detections in three of them reveal a few × 108 M ☉ of FIR-emitting warm dust and 1010 M ☉ of molecular gas in the quasar host galaxies. All these results argue for massive star formation in the quasar host galaxies, with estimated star formation rates of a few hundred M ☉ yr–1. Additionally, the higher FIR-to-AGN luminosity ratio found in these 250 GHz detected faint quasars also suggests a higher ratio between star formation rate and supermassive black hole accretion rate than the UV/optically most luminous quasars at z ~ 6.
The Astronomical Journal 08/2011; 142(4):101. · 4.03 Impact Factor
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Ran Wang,
Jeff Wagg, Chris L. Carilli,
Fabian Walter,
Dominik A. Riechers,
Chris Willott,
Frank Bertoldi,
Alain Omont,
Alexandre Beelen,
Pierre Cox,
Michael A. Strauss,
Jacqueline Bergeron,
Thierry Forveille,
Karl M. Menten,
Xiaohui Fan
[show abstract]
[hide abstract]
ABSTRACT: We report new observations of CO (2-1) line emission toward five z~6 quasars
using the Ka-band receiver system on the Expanded Very Large Array (EVLA).
Strong detections were obtained in two of them, SDSS J092721.82+200123.7 and
CFHQS J142952.17+544717.6, and a marginal detection was obtained in another
source, SDSS J084035.09+562419.9. Upper limits of the CO (2-1) line emission
have been obtained for the other two objects. The CO (2-1) line detection in
J0927+2001, together with previous measurements of the CO (6-5) and (5-4)
lines, reveals important constraints on the CO excitation in the central ~10
kpc region of the quasar host galaxy. The CO (2-1) line emission from
J1429+5447 is resolved into two distinct peaks separated by 1.2" (~6.9 kpc),
indicating a possible gas-rich, major merging system, and the optical quasar
position is consistent with the west peak. This result is in good agreement
with the picture in which intense host galaxy star formation is coeval with
rapid supermassive black hole accretion in the most distant universe. The two
EVLA detections are ideal targets for further high-resolution imaging (e.g.,
with ALMA or EVLA observations) to study the gas distribution, dynamics, and
SMBH-bulge mass relation in these earliest quasar-host galaxy systems.
05/2011;
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[show abstract]
[hide abstract]
ABSTRACT: Using the 12m APEX telescope, we have detected redshifted emission from the 157.74micron [CII] line in the z=4.4074 quasar BRI1335-0417. The linewidth and redshift are in good agreement with previous observations of high-J CO line emission. We measure a [CII] line luminosity, L_[CII] = (16.4 +/- 2.6)x10^9 Lsun, making BRI~1335-0417 the most luminous, unlensed [CII] line emitter known at high-redshift. The [CII]-to-FIR luminosity ratio of (5.3+/-0.8)x10^-4 is ~3x higher than expected for an average object with a FIR luminosity L_FIR = 3.1x10^13 Lsun, if this ratio were to follow the trend observed in other FIR-bright galaxies that have been detected in [CII] line emission. These new data suggest that the scatter in the [CII]-to-FIR luminosity ratio could be larger than previously expected for high luminosity objects. BR1335-0417 has a similar FIR luminosity and [CII]/CO luminosity compared to local ULIRGS and appears to be a gas-rich merger forming stars at a rate of a few thousand solar masses per year. Comment: A&A accepted
08/2010;
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[show abstract]
[hide abstract]
ABSTRACT: We report the detection of the CO J=1-0 emission line in three near-infrared selected star-forming galaxies at z~1.5 with the Very Large Array (VLA) and the Green Bank telescope (GBT). These observations directly trace the bulk of molecular gas in these galaxies. We find H_2 gas masses of 8.3 \pm 1.9 x 10^{10} M_sun, 5.6 \pm 1.4 x 10^{10} M_sun and 1.23 \pm 0.34 x 10^{11} M_sun for BzK-4171, BzK-21000 and BzK-16000, respectively, assuming a conversion alpha_CO=3.6 M_sun (K km s^{-1} pc^{2})^{-1}. We combined our observations with previous CO 2-1 detections of these galaxies to study the properties of their molecular gas. We find brightness temperature ratios between the CO 2-1 and CO 1-0 emission lines of 0.80_{-0.22}^{+0.35}, 1.22_{-0.36}^{+0.61} and 0.41_{-0.13}^{+0.23} for BzK-4171, BzK-21000 and BzK-16000, respectively. At the depth of our observations it is not possible to discern between thermodynamic equilibrium or sub-thermal excitation of the molecular gas at J=2. However, the low temperature ratio found for BzK-16000 suggests sub-thermal excitation of CO already at J=2. For BzK-21000, a Large Velocity Gradient model of its CO emission confirms previous results of the low-excitation of the molecular gas at J=3. From a stacked map of the CO 1-0 images, we measure a CO 2-1 to CO 1-0 brightness temperature ratio of 0.92_{-0.19}^{+0.28}. This suggests that, on average, the gas in these galaxies is thermalized up to J=2, has star-formation efficiencies of ~100 L_sun (K km s^{-1} pc^2)^{-1} and gas consumption timescales of ~0.4 Gyr, unlike SMGs and QSOs at high redshifts. Comment: Accepted for publication in ApJ
05/2010;
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Ran Wang, Chris L. Carilli,
R. Neri,
D. A. Riechers,
Jeff Wagg,
Fabian Walter,
Frank Bertoldi,
Karl M. Menten,
Alain Omont,
Pierre Cox,
and Xiaohui Fan
[show abstract]
[hide abstract]
ABSTRACT: We report our new observations of redshifted carbon monoxide emission from six z ~ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z ~ 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 1010 M ☉ within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ~ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ~ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of ~0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift.
The Astrophysical Journal 04/2010; 714(1):699. · 6.02 Impact Factor
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Linhua Jiang,
Xiaohui Fan,
W N Brandt, Chris L Carilli,
Eiichi Egami,
Dean C Hines,
Jaron D Kurk,
Gordon T Richards,
Yue Shen,
Michael A Strauss,
Marianne Vestergaard,
Fabian Walter
[show abstract]
[hide abstract]
ABSTRACT: The most distant quasars known, at redshifts z approximately 6, generally have properties indistinguishable from those of lower-redshift quasars in the rest-frame ultraviolet/optical and X-ray bands. This puzzling result suggests that these distant quasars are evolved objects even though the Universe was only seven per cent of its current age at these redshifts. Recently one z approximately 6 quasar was shown not to have any detectable emission from hot dust, but it was unclear whether that indicated different hot-dust properties at high redshift or if it is simply an outlier. Here we report the discovery of a second quasar without hot-dust emission in a sample of 21 z approximately 6 quasars. Such apparently hot-dust-free quasars have no counterparts at low redshift. Moreover, we demonstrate that the hot-dust abundance in the 21 quasars builds up in tandem with the growth of the central black hole, whereas at low redshift it is almost independent of the black hole mass. Thus z approximately 6 quasars are indeed at an early evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them.
Nature 03/2010; 464(7287):380-3. · 36.28 Impact Factor
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Ran Wang, Chris L. Carilli,
R. Neri,
D. A. Riechers,
Jeff Wagg,
Fabian Walter,
Frank Bertoldi,
Karl M. Menten,
Alain Omont,
Pierre Cox,
Xiaohui Fan
[show abstract]
[hide abstract]
ABSTRACT: We report our new observations of redshifted carbon monoxide emission from six z~6 quasars, using the PdBI. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic reionization. Complementary results are also presented for low-J CO lines observed at the GBT and the VLA, and dust continuum from five of these sources with the SHARC-II bolometer camera at the CSO. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z~6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 10^10 M_sun within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z~6 quasars and samples of CO-detected $1.4\leq z\leq5$ quasars and submillimeter galaxies. Most of the CO-detected quasars at z~6 follow the far infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole--bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The results place important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift. Comment: 34 pages, 8 figures, accepted for publication in ApJ
02/2010;
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Ran Wang, Chris L. Carilli,
Jeff Wagg,
Frank Bertoldi,
Fabian Walter,
Karl M. Menten,
Alain Omont,
Pierre Cox,
Michael A. Strauss,
Xiaohui Fan,
Linhua Jiang,
and Donald P. Schneider
[show abstract]
[hide abstract]
ABSTRACT: We report new continuum observations of 14 z ~ 6 quasars at 250 GHz and 14 quasars at 1.4 GHz. We summarize all recent millimeter and radio observations of the sample of the 33 quasars known with 5.71 ≤ z≤ 6.43 and present a study of the rest-frame far-infrared (FIR) properties of this sample. These quasars were observed with the Max Planck Millimeter Bolometer Array (MAMBO) at 250 GHz with mJy sensitivity, and 30% of them were detected. We also recover the average 250 GHz flux density of the MAMBO undetected sources at 4 σ by stacking the on-source measurements. The derived mean radio-to-UV spectral energy distributions (SEDs) of the full sample and the 250 GHz nondetections show no significant differences from lower redshift optical quasars. Obvious FIR excesses are seen in the individual SEDs of the strong 250 GHz detections, with FIR-to-radio emission ratios consistent with those of typical star-forming galaxies. Most 250 GHz-detected sources follow the LFIR-Lbol relationship derived from a sample of local IR-luminous quasars (LIR > 1012 L☉), while the average LFIR/Lbol ratio of the nondetections is consistent with that of the optically selected PG quasars. The MAMBO detections also tend to have weaker Lyα emission than the nondetected sources. We discuss possible FIR dust-heating sources and critically assess the possibility of active star formation in the host galaxies of the z ~ 6 quasars. The average star formation rate of the MAMBO nondetections is likely to be less than a few hundred M☉ yr−1, but in the strong detections, the host galaxy star formation is probably at a rate of 103 M☉ yr−1, which dominates the FIR dust heating.
The Astrophysical Journal 12/2008; 687(2):848. · 6.02 Impact Factor
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Manuel Aravena,
Frank Bertoldi,
Eva Schinnerer,
Axel Weiss,
Knud Jahnke, Chris L. Carilli,
David T. Frayer,
Christian Henkel,
Marcella Brusa,
Karl M. Menten,
Mara Salvato,
Vernesa Smolcic
[show abstract]
[hide abstract]
ABSTRACT: Using the IRAM 30m telescope, we have detected the CO J=2-1, 4-3, 5-4, and 6-5 emission lines in the millimeter-bright, blank-field selected AGN COSMOS J100038+020822 at redshift z=1.8275. The sub-local thermodynamic equilibrium (LTE) excitation of the J=4 level implies that the gas is less excited than that in typical nearby starburst galaxies such as NGC253, and in the high-redshift quasars studied to date, such as J1148+5251 or BR1202-0725. Large velocity gradient (LVG) modeling of the CO line spectral energy distribution (CO SED; flux density vs. rotational quantum number) yields H2 densities in the range 10^{3.5}--10^{4.0} cm-3, and kinetic temperatures between 50 K and 200 K. The H2 mass of (3.6 - 5.4) x 10^{10} M_sun implied by the line intensities compares well with our estimate of the dynamical mass within the inner 1.5 kpc of the object. Fitting a two-component gray body spectrum, we find a dust mass of 1.2 x 10^{9} M_sun, and cold and hot dust temperatures of 42+/-5 K and 160+/-25 K, respectively. The broad MgII line allows us to estimate the mass of the central black hole as 1.7 x 10^{9} M_sun. Although the optical spectrum and multi-wavelength SED matches those of an average QSO, the molecular gas content and dust properties resemble those of known submillimeter galaxies (SMGs). The optical morphology of this source shows tidal tails that suggest a recent interaction or merger. Since it shares properties of both starburst and AGN, this object appears to be in a transition from a strongly starforming submillimeter galaxy to a QSO. Comment: Accepted for publication in Astronomy & Astrophysics (A&A)
09/2008;
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Ran Wang,
Jeff Wagg, Chris L. Carilli,
Dominic J. Benford,
C. Darren Dowell,
Frank Bertoldi,
Fabian Walter,
Karl M. Menten,
Alain Omont,
Pierre Cox,
Michael A. Strauss,
Xiaohui Fan,
and Linhua Jiang
[show abstract]
[hide abstract]
ABSTRACT: We present observations of four z ≥ 5 SDSS quasars at 350 μm with the SHARC-II bolometer camera on the Caltech Submillimeter Observatory. These are among the deepest observations that have been made by SHARC-II at 350 μm, and three quasars are detected at ≥3σ significance, greatly increasing the sample of 350 μm (corresponds to rest frame wavelengths of <60 μm at z ≥ 5), detected high-redshift quasars. The derived rest frame far-infrared (FIR) emission in the three detected sources is about five to ten times stronger than that expected from the average spectral energy distribution (SED) of the local quasars given the same 1450 Å luminosity. Combining the previous submillimeter and millimeter observations at longer wavelengths, the temperatures of the FIR-emitting warm dust from the three quasar detections are estimated to be in the range of 39-52 K. Additionally, the FIR-to-radio SEDs of the three 350 μm detections are consistent with the emission from typical star-forming galaxies. The FIR luminosities are ~1013 L ☉ and the dust masses are ≥108 M ☉. These results confirm that huge amounts of warm dust can exist in the host galaxies of optically bright quasars as early as z ~ 6. The universe is so young at these epochs (~1 Gyr) that a rapid dust-formation mechanism is required. We estimate the size of the FIR dust-emission region to be about a few kpc, and further provide a comparison of the SEDs among different kinds of dust-emitting sources to investigate the dominant dust-heating mechanism.
The Astronomical Journal 03/2008; 135(4):1201. · 4.03 Impact Factor
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Ran Wang, Chris L. Carilli,
Alexandre Beelen,
Frank Bertoldi,
Xiaohui Fan,
Fabian Walter,
Karl M. Menten,
Alain Omont,
Pierre Cox,
Michael A. Strauss,
and Linhua Jiang
[show abstract]
[hide abstract]
ABSTRACT: We present millimeter and radio observations of 13 SDSS quasars at redshifts z ~ 6. We observed 11 of them with the Max Planck Millimeter Bolometer Array (MAMBO-2) at the IRAM 30 m telescope at 250 GHz and all of them with the Very Large Array (VLA) at 1.4 GHz. Four sources are detected by MAMBO-2 and six are detected by the VLA at the 3 σ level. These sources, together with another six published in previous papers, yield a submillimeter/millimeter- and radio-observed SDSS quasar sample at z ~ 6. We use this sample to investigate the far-infrared (FIR) and radio properties of optically bright quasars in the early universe. We compare this sample to lower redshift samples of quasars observed in the submillimeter and millimeter wavelengths [(sub)mm] and find that the distribution of the FIR-to-B-band optical luminosity ratio (LFIR/LB) is similar from z ~ 2 to 6. We find a weak correlation between the FIR luminosity (LFIR) and B-band optical luminosity (LB) by including the (sub)mm observed samples at all redshifts. Some strong (sub)mm detections in the z ~ 6 sample have radio-to-FIR ratios within the range defined by star-forming galaxies, which suggests possible coeval star-forming activity with the powerful AGN in these sources. We calculate the rest-frame radio-to-optical ratios (R = Lν,1.4 GHz/Lν,4400 Å) for all of the VLA-observed sources in the z ~ 6 quasar sample. Only one radio detection in this sample, J083643.85+005453.3, has R ~ 40 and can be considered radio-loud. There are no strong radio sources (R ≥ 100) among these SDSS quasars at z ~ 6. These data are consistent with, although do not set strong constraints on, a decreasing radio-loud quasar fraction with increasing redshift.
The Astronomical Journal 12/2007; 134(2):617. · 4.03 Impact Factor
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Linhua Jiang,
Xiaohui Fan,
Dean C. Hines,
Yong Shi,
Marianne Vestergaard,
Frank Bertoldi,
W. N. Brandt, Chris L. Carilli,
Pierre Cox,
Emeric Le Floc'h,
Laura Pentericci,
Gordon T. Richards,
George H. Rieke,
Donald P. Schneider,
Michael A. Strauss,
Fabian Walter,
and J. Brinkmann
[show abstract]
[hide abstract]
ABSTRACT: We present Spitzer observations of 13 z ~ 6 quasars using the Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS). All the quasars except SDSS J000552.34-000655.8 (SDSS J0005-0006) were detected with high signal-to-noise ratio in the four IRAC channels and the MIPS 24 μm band, while SDSS J0005-0006 was marginally detected in the IRAC 8.0 μm band and not detected in the MIPS 24 μm band. We find that most of these quasars have prominent emission from hot dust, as evidenced by the observed 24 μm fluxes. Their spectral energy distributions (SEDs) are similar to those of low-redshift quasars at rest frame 0.15-3.5 μm, suggesting that accretion disks and hot-dust structures for these sources have already reached maturity. However, SDSS J0005-0006 has an unusual SED that lies significantly below low-redshift SED templates at rest frame 1 and 3.5 μm and thus shows a strong near-IR (NIR) deficit and no hot-dust emission. Type I quasars with extremely small NIR-to-optical flux ratios such as SDSS J0005-0006 are not found in low-redshift quasar samples, indicating that SDSS J0005-0006 has different dust properties at high redshift. We combine the Spitzer observations with X-ray, UV/optical, millimeter/submillimeter, and radio observations to determine bolometric luminosities for all the quasars. We find that the four quasars with central black hole mass measurements have Eddington ratios of order unity.
The Astronomical Journal 12/2007; 132(5):2127. · 4.03 Impact Factor
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Linhua Jiang,
Xiaohui Fan,
Dean C. Hines,
Yong Shi,
Marianne Vestergaard,
Frank Bertoldi,
W. N. Brandt, Chris L. Carilli,
Pierre Cox,
Emeric Le Floc'h,
Laura Pentericci,
Gordon T. Richards,
George H. Rieke,
Donald P. Schneider,
Michael A. Strauss,
Fabian Walter,
J. Brinkmann
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ABSTRACT: We present Spitzer observations of thirteen z~6 quasars using the Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS). All the quasars except SDSS J000552.34-000655.8 (SDSS J0005-0006) were detected with high S/N in the four IRAC channels and the MIPS 24um band, while SDSS J0005-0006 was marginally detected in the IRAC 8.0um band, and not detected in the MIPS 24um band. We find that most of these quasars have prominent emission from hot dust as evidenced by the observed 24um fluxes. Their spectral energy distributions (SEDs) are similar to those of low-redshift quasars at rest-frame 0.15-3.5 um, suggesting that accretion disks and hot-dust structures for these sources already have reached maturity. However, SDSS J0005-0006 has an unusual SED that lies significantly below low-redshift SED templates at rest-frame 1 and 3.5 um, and thus shows a strong near-IR (NIR) deficit and no hot-dust emission. Type I quasars with extremely small NIR-to-optical flux ratios like SDSS J0005-0006 are not found in low-redshift quasar samples, indicating that SDSS J0005-0006 has different dust properties at high redshift. We combine the Spitzer observations with X-ray, UV/optical, mm/submm and radio observations to determine bolometric luminosities for all the quasars. We find that the four quasars with central black-hole mass measurements have Eddington ratios of order unity. Comment: 22 pages, 5 figures, accepted by AJ
07/2006;
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ABSTRACT: We review recent progress in the study of dust and gas in optically
luminous, radio-quiet high-z quasars (QSOs). Highlights include the
detection of thermal dust continuum in ~80 1 < z < 6.4 quasars,
and molecular line data in 11 of them including J1148+5152, the farthest
known QSO at z = 6.42, indicating the presence of massive reservoirs of
dust and molecular gas. The importance of ALMA and Herschel in these
studies is underlined.
12/2004; 577:115-120.
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ABSTRACT: We summarise preliminary results of our search for optical and near-infrared counterparts to millimeter continuum background
sources discovered in deep blank field surveys with the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30m telescope.
A good fraction of the MAMBO sources do show optical and near-IR counterparts, with evidence for clustering of galaxies around
the MAMBO sources.
01/1970: pages 123-128;
