We present a survey of the C ii 158 m line and underlying far-infrared (FIR) dust continuum emission in a sample of 27 quasars using the Atacama Large Millimeter Array (ALMA) at resolution. The C ii ...line was significantly detected (at - ) in 23 sources (85%). We find typical line luminosities of , and an average line width of ∼385 . The C ii-to-far-infrared luminosity ratios (C ii/FIR) in our sources span one order of magnitude, highlighting a variety of conditions in the star-forming medium. Four quasar host galaxies are clearly resolved in their C ii emission on a few kpc scales. Basic estimates of the dynamical masses of the host galaxies give masses between 2 × 1010 and 2 × 1011 , i.e., more than an order of magnitude below what is expected from local scaling relations, given the available limits on the masses of the central black holes ( , assuming Eddington-limited accretion). In stacked ALMA C ii spectra of individual sources in our sample, we find no evidence of a deviation from a single Gaussian profile. The quasar luminosity does not strongly correlate with either the C ii luminosity or equivalent width. This survey (with typical on-source integration times of 8 minutes) showcases the unparalleled sensitivity of ALMA at millimeter wavelengths, and offers a unique reference sample for the study of the first massive galaxies in the universe.
During reionization, neutral hydrogen in the intergalactic medium (IGM) imprints a damping wing absorption feature on the spectrum of high-redshift quasars. A detection of this signature provides ...compelling evidence for a significantly neutral universe, and enables measurements of the hydrogen neutral fraction xH i(z) at that epoch. Obtaining reliable quantitative constraints from this technique, however, is challenging due to stochasticity induced by the patchy inside-out topology of reionization, degeneracies with quasar lifetime, and the unknown unabsorbed quasar spectrum close to rest-frame Ly . We combine a large-volume semi-numerical simulation of reionization topology with 1D radiative transfer through high-resolution hydrodynamical simulations of the high-redshift universe to construct models of quasar transmission spectra during reionization. Our state-of-the-art approach captures the distribution of damping wing strengths in biased quasar halos that should have reionized earlier, as well as the erosion of neutral gas in the quasar environment caused by its own ionizing radiation. Combining this detailed model with our new technique for predicting the quasar continuum and its associated uncertainty, we introduce a Bayesian statistical method to jointly constrain the neutral fraction of the universe and the quasar lifetime from individual quasar spectra. We apply this methodology to the spectra of the two quasars with the highest redshifts known, ULAS J1120+0641 and ULAS J1342+0928, and measure volume-averaged neutral fractions and (posterior medians and 68% credible intervals) when marginalized over quasar lifetimes of 103 ≤ tq ≤ 108 yr.
We present a study of the C ii 158 m line and underlying far-infrared (FIR) continuum emission of 27 quasar host galaxies at z ∼ 6, traced by the Atacama Large Millimeter/submillimeter Array at a ...spatial resolution of ∼1 physical kpc. The C ii emission in the bright, central regions of the quasars have sizes of 1.0-4.8 kpc. The dust continuum emission is typically more compact than C ii. We find that 13/27 quasars (approximately one-half) have companion galaxies in the field, at projected separations of 3-90 kpc. The position of dust emission and the Gaia-corrected positions of the central accreting black holes are cospatial (typical offsets 0 1). This suggests that the central black holes are located at the bottom of the gravitational wells of the dark matter halos in which the quasar hosts reside. Some outliers with offsets of ∼500 pc can be linked to disturbed morphologies, most likely due to ongoing or recent mergers. We find no correlation between the central brightness of the FIR emission and the bolometric luminosity of the accreting black hole. The FIR-derived star formation rate densities (SFRDs) in the host galaxies peak at the galaxies' centers, at typical values between 100 and 1000 M yr−1 kpc−2. These values are below the Eddington limit for star formation, but similar to those found in local ultraluminous infrared galaxies. The SFRDs drop toward larger radii by an order of magnitude. Likewise, the C ii/FIR luminosity ratios of the quasar hosts are lowest in their centers (few ×10−4) and increase by a factor of a few toward the galaxies' outskirts, consistent with resolved studies of lower-redshift sources.
ABSTRACT We present ALMA detections of the C ii 158 m emission line and the underlying far-infrared (FIR) continuum of three quasars at 6.6 < z < 6.9 selected from the VIKING survey. The C ii line ...fluxes range between 1.6 and 3.4 Jy km s−1 (C ii luminosities ∼(1.9-3.9) × 109 L ). We measure continuum flux densities of 0.56-3.29 mJy around 158 m (rest frame), with implied FIR luminosities of (0.6-7.5) × 1012 L and dust masses Md = (0.7-24) × 108 M . In one quasar we derive a dust temperature of K from the continuum slope, below the canonical value of 47 K. Assuming that the C ii and continuum emission are powered by star formation, we find star formation rates from 100 to 1600 M yr−1 based on local scaling relations. The LC ii/LFIR ratios in the quasar hosts span a wide range from (0.3-4.6) × 10−3, including one quasar with a ratio that is consistent with local star-forming galaxies. We find that the strength of the LC ii and 158 m continuum emission in z 6 quasar hosts correlates with the quasar's bolometric luminosity. In one quasar, the C ii line is significantly redshifted by ∼1700 km s−1 with respect to the Mg ii broad emission line. Comparing to values in the literature, we find that, on average, the Mg ii is blueshifted by 480 km s−1 (with a standard deviation of 630 km s−1) with respect to the host galaxy redshift, i.e., one of our quasars is an extreme outlier. Through modeling we can rule out a flat rotation curve for our brightest C ii emitter. Finally, we find that the ratio of black hole mass to host galaxy (dynamical) mass is higher by a factor of 3-4 (with significant scatter) than local relations.
The Kinematics of z ≳ 6 Quasar Host Galaxies Neeleman, Marcel; Novak, Mladen; Venemans, Bram P. ...
Astrophysical journal/The Astrophysical journal,
04/2021, Letnik:
911, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
We explore the kinematics of 27
z
≳ 6 quasar host galaxies observed in C
ii
158
μ
m (C
ii
) emission with the Atacama Large Millimeter/submillimeter Array at a resolution of ≈025. We find ...that nine of the galaxies show disturbed C
ii
emission, due to either a close companion galaxy or a recent merger. Ten galaxies have smooth velocity gradients consistent with the emission arising from a gaseous disk. The remaining eight quasar host galaxies show no velocity gradient, suggesting that the gas in these systems is dispersion dominated. All galaxies show high velocity dispersions with a mean of 129 ± 10 km s
−1
. To provide an estimate of the dynamical mass within twice the half-light radius of the quasar host galaxy, we model the kinematics of the C
ii
emission line using our publicly available kinematic fitting code,
qubefit
. This results in a mean dynamical mass of 5.0 ± 0.8( ± 3.5) × 10
10
M
⊙
. Comparison between the dynamical mass and the mass of the supermassive black hole reveals that the sample falls above the locally derived bulge mass–black hole mass relation at 2.4
σ
significance. This result is robust even if we account for the large systematic uncertainties. Using several different estimators for the molecular mass, we estimate a gas mass fraction of >10%, indicating that gas makes up a large fraction of the baryonic mass of
z
≳ 6 quasar host galaxies. Finally, we speculate that the large variety in C
ii
kinematics is an indication that gas accretion onto
z
≳ 6 supermassive black holes is not caused by a single precipitating factor.
Abstract
We present the
z
≈ 6 type-1 quasar luminosity function (QLF), based on the Pan-STARRS1 (PS1) quasar survey. The PS1 sample includes 125 quasars at
z
≈ 5.7–6.2, with −28 ≲
M
1450
≲ −25. With ...the addition of 48 fainter quasars from the SHELLQs survey, we evaluate the
z
≈ 6 QLF over −28 ≲
M
1450
≲ −22. Adopting a double power law with an exponential evolution of the quasar density (Φ(
z
) ∝ 10
k
(
z
−6)
;
k
= −0.7), we use a maximum likelihood method to model our data. We find a break magnitude of
M
*
=
−
26.38
−
0.60
+
0.79
mag
, a faint-end slope of
α
=
−
1.70
−
0.19
+
0.29
, and a steep bright-end slope of
β
=
−
3.84
−
1.21
+
0.63
. Based on our new QLF model, we determine the quasar comoving spatial density at
z
≈ 6 to be
n
(
M
1450
<
−
26
)
=
1.16
−
0.12
+
0.13
cGpc
−
3
. In comparison with the literature, we find the quasar density to evolve with a constant value of
k
≈ −0.7, from
z
≈ 7 to
z
≈ 4. Additionally, we derive an ionizing emissivity of
ϵ
912
(
z
=
6
)
=
7.23
−
1.02
+
1.65
×
10
22
erg
s
−
1
Hz
−
1
cMpc
−
3
, based on the QLF measurement. Given standard assumptions, and the recent measurement of the mean free path by Becker et al. at
z
≈ 6, we calculate an H
i
photoionizing rate of Γ
H I
(
z
= 6) ≈ 6 × 10
−16
s
−1
, strongly disfavoring a dominant role of quasars in hydrogen reionization.
Molecular Gas in Three z ∼ 7 Quasar Host Galaxies Venemans, Bram P.; Walter, Fabian; Decarli, Roberto ...
Astrophysical journal/The Astrophysical journal,
08/2017, Letnik:
845, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present ALMA band 3 observations of the CO(6-5), CO(7-6), and C i 369 m emission lines in three of the highest-redshift quasar host galaxies at . These measurements constitute the highest-redshift ...CO detections to date. The target quasars have previously been detected in C ii 158 m emission and the underlying FIR dust continuum. We detect (spatially unresolved, at a resolution of >2″, or 14 kpc) CO emission in all three quasar hosts. In two sources, we detect the continuum emission around 400 m (rest-frame), and in one source we detect C i at low significance. We derive molecular gas reservoirs of (1-3) × 1010 in the quasar hosts, i.e., approximately only 10 times the mass of their central supermassive black holes. The extrapolated C ii-to-CO(1-0) luminosity ratio is 2500-4200, consistent with measurements in galaxies at lower redshift. The detection of the C i line in one quasar host galaxy and the limit on the C i emission in the other two hosts enables a first characterization of the physical properties of the interstellar medium in z ∼ 7 quasar hosts. In the sources, the derived global CO/C ii/C i line ratios are consistent with expectations from photodissociation regions, but not X-ray-dominated regions. This suggest that quantities derived from the molecular gas and dust emission are related to ongoing star-formation activity in the quasar hosts, providing further evidence that the quasar hosts studied here harbor intense starbursts in addition to their active nucleus.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the C ii fine-structure line and the underlying far-infrared (FIR) dust continuum emission in J1120+0641, the most ...distant quasar currently known ( ). We also present observations targeting the CO(2-1), CO(7-6), and C i 369 m lines in the same source obtained at the Very Large Array and Plateau de Bure Interferometer. We find a C ii line flux of Jy and a continuum flux density of mJy beam−1, consistent with previous unresolved measurements. No other source is detected in continuum or C ii emission in the field covered by ALMA (∼ 25″). At the resolution of our ALMA observations (0 23, or 1.2 kpc, a factor of ∼70 smaller beam area compared to previous measurements), we find that the majority of the emission is very compact: a high fraction (∼80%) of the total line and continuum flux is associated with a region 1-1.5 kpc in diameter. The remaining ∼20% of the emission is distributed over a larger area with radius 4 kpc. The C ii emission does not exhibit ordered motion on kiloparsec scales: applying the virial theorem yields an upper limit on the dynamical mass of the host galaxy of , only ∼20 × higher than the central black hole (BH). The other targeted lines (CO(2-1), CO(7-6), and C i) are not detected, but the limits of the line ratios with respect to the C ii emission imply that the heating in the quasar host is dominated by star formation, and not by the accreting BH. The star formation rate (SFR) implied by the FIR continuum is 105-340 , with a resulting SFR surface density of ∼100-350 kpc−2, well below the value for Eddington-accretion-limited star formation.
We present IRAM/NOEMA and JVLA observations of the quasar J1342+0928 at z = 7.54 and report detections of copious amounts of dust and C ii emission in the interstellar medium (ISM) of its host ...galaxy. At this redshift, the age of the universe is 690 Myr, about 10% younger than the redshift of the previous quasar record holder. Yet, the ISM of this new quasar host galaxy is significantly enriched by metals, as evidenced by the detection of the C ii 158 m cooling line and the underlying far-infrared (FIR) dust continuum emission. To the first order, the FIR properties of this quasar host are similar to those found at a slightly lower redshift ( ), making this source by far the FIR-brightest galaxy known at . The C ii emission is spatially unresolved, with an upper limit on the diameter of 7 kpc. Together with the measured FWHM of the C ii line, this yields a dynamical mass of the host of . Using standard assumptions about the dust temperature and emissivity, the NOEMA measurements give a dust mass of . The brightness of the C ii luminosity, together with the high dust mass, imply active ongoing star formation in the quasar host. Using C ii-SFR scaling relations, we derive star formation rates of 85-545 yr−1 in the host, consistent with the values derived from the dust continuum. Indeed, an episode of such past high star formation is needed to explain the presence of ∼108 M☉ of dust implied by the observations.
![An ALMA [C ii] Survey of 27...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "An ALMA [C ii] Survey of 27 Quasars at z > 5.94")
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