Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAtomic carbon in PSS 2322+1944, a quasar at redshift 4.12
123
0
0.0
(
0
)
Authors
J. Pety
Ask ChatGPT about the research
No Arabic abstract
We report the detection of the 3P1 to 3P0 fine-structure line of neutral carbon in the z=4.12 quasar PSS 2322+1944, obtained at the IRAM Plateau de Bure interferometer. The CI 3P1-3P0 line is detected with a signal-to-noise ratio of about 6 with a peak intensity of about 2.5 mJy and a velocity-integrated line flux of 0.81+-0.12 Jy.km/s. Assuming an excitation temperature of 43 K (equal to the dust temperature), we derive a mass of neutral carbon (corrected for magnification) of about 1.2e7 Msun. In PSS 2322+1944, the cooling due to C is about 6 times smaller than for CO, whereas the CO and C cooling represents about 1e-4 of the far-infrared continuum and more than half of the cooling due to C+.
rate research
Read More
We present observations of CO 1-0 and CO 2-1 emission from the z = 4.12 QSO PSS 2322+1944 using the Very Large Array. The CO emission is extended on a spatial scale of 2. This extension could reflect the double nature of the QSO as seen in the optical, or could be diffuse emission with a (redshift corrected) mean brightness temperature of 2.8 K for the CO 2-1 line. We find the CO excitation conditions are lower than in two other IR-luminous z > 4 QSOs, suggesting the presence of a significant contribution from cooler, lower density molecular gas (n(H_2) = 5x10^3 /cm^3), although such a conclusion is complicated by the possibility of differential gravitational magnification.
Using the IRAM interferometer we have detected J=4-3 and 5-4 CO line emission toward the radio quiet quasar PSS2322+1944. At a redshift of z_CO=4.1199 this is the fourth and strongest detection of CO at z>4. The velocity-integrated CO J=4-3 and J=5-4 line fluxes are 4.21+-0.40 and 3.74+-0.56 Jy km/s, and the linewidth is ~300 km/s. The CO J=10-9 line was searched for but not detected with an upper intensity limit of 30 mJy. The 1.35 mm (250 mum rest wavelength) continuum flux density is 7.5+-1.3 mJy, in agreement with previous bolometer measurements at 1.2 mm with the 30-m IRAM telescope. The 3mm (580 mum rest wavelength) continuum is not detected with a 3 sigma upper limit of 0.7mJy. We also report observations of the 450 mum continuum in PSS2322+1944 using the SCUBA array at the JCMT. The quasar was detected with a 450 mum flux density of 79+-19mJy. At the angular resolution of 4.8 x 2.1 at 1.3mm and 6.2 x 4.9 at 3.2 mm, the interferometer observations do not show evidence of spatial extension in the continuum or CO line emission. Assuming no gravitational magnification, we estimate a molecular gas mass of ~2.5x10^11 M_sun. The molecular gas is warm (40-100 K) and dense (10^3.5-10^4.1 cm^-3). The infrared-to-CO luminosity ratio is ~185 L_sun/(K km/s pc^2), comparable to the values found for ultraluminous infrared galaxies. The detection of CO emission in this high redshift QSO provides further evidence that the radio emission and the millimeter to submillimeter continuum emission are predominantly powered by a starburst which is coeval with the AGN activity.
We present a survey of atomic carbon (CI) emission in high-redshift (z>2) submillimeter galaxies (SMGs) and quasar host galaxies (QSOs). Sensitive observations of the CI(3P_1->3P_0) and CI(3P_2->3P_1) lines have been obtained at the IRAM Plateau de Bure interferometer and the IRAM 30m telescope. A total of 16 CI lines have been targeted in 10 sources, leading to a total of 10 detected lines --- this doubles the number of CI observations at high redshift to date. We include previously published CI observations (an additional 5 detected sources) in our analysis. Our main finding is that the CI properties of the studied high-redshift systems do not differ significantly from what is found in low-redshift systems, including the Milky Way. The CI(3P_2->3P_1)/CI(3P_1->3P_0) and the CI(3P_1->3P_0)/12CO(3-2) line luminosity (L) ratios change little in our sample, with respective ratios of 0.55+/-0.15 and 0.32+/-0.13. The CI lines are not an important contributor to cooling of the molecular gas (average L_CI/L_FIR ~ (7.7+/-4.6) x 10^-6). We derive a mean carbon excitation temperature of 29.1+/-6.3 K, broadly consistent with dust temperatures derived for high-redshift starforming systems, but lower than gas temperatures typically derived for starbursts in the local universe. The carbon abundance of X_CI/X_H2~8.4+/-3.5 x 10^-5 is of the same order as found in the Milky Way and nearby galaxies. This implies that the high-z galaxies studied here are significantly enriched in carbon on galactic scales, even though the look-back times are considerable (the average redshift of the sample sources corresponds to an age of the universe of ~2 Gyr).
Distant quasars are unique tracers to study the formation of the earliest supermassive black holes (SMBHs) and the history of cosmic reionization. Despite extensive efforts, only two quasars have been found at $zge7.5$, due to a combination of their low spatial density and the high contamination rate in quasar selection. We report the discovery of a luminous quasar at $z=7.642$, J0313$-$1806, the most distant quasar yet known. This quasar has a bolometric luminosity of $3.6times10^{13} L_odot$. Deep spectroscopic observations reveal a SMBH with a mass of $(1.6pm0.4) times10^9M_odot$ in this quasar. The existence of such a massive SMBH just $sim$670 million years after the Big Bang challenges significantly theoretical models of SMBH growth. In addition, the quasar spectrum exhibits strong broad absorption line (BAL) features in CIV and SiIV, with a maximum velocity close to 20% of the speed of light. The relativistic BAL features, combined with a strongly blueshifted CIV emission line, indicate that there is a strong active galactic nucleus (AGN) driven outflow in this system. ALMA observations detect the dust continuum and [CII] emission from the quasar host galaxy, yielding an accurate redshift of $7.6423 pm 0.0013$ and suggesting that the quasar is hosted by an intensely star-forming galaxy, with a star formation rate of $rmsim 200 ~M_odot ~yr^{-1}$ and a dust mass of $sim7times10^7~M_odot$. Followup observations of this reionization-era BAL quasar will provide a powerful probe of the effects of AGN feedback on the growth of the earliest massive galaxies.
Large-scale surveys over the last years have revealed about 300 QSOs at redshift above 6. Follow-up observations identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas of the host galaxy, or high CIV-MgII velocity shifts. In particular, the discovery of luminous high-redshift quasars suggests that at least some black holes likely have large masses at birth and grow efficiently. We aim at quantifying quasar pairs at high redshift for a large sample of objects. This provides a new key constraint on a combination of parameters related to the origin and assembly for the most massive black holes: BH formation efficiency and clustering, growth efficiency and relative contribution of BH mergers. We observed 116 spectroscopically confirmed QSOs around redshift 6 with the simultaneous 7-channel imager GROND in order to search for companions. Applying identical colour-colour cuts as for those which led to the spectroscopically confirmed QSO, we perform LePHARE fits to the 26 best QSO pair candidates, and obtained spectroscopic observations for 11 of those. e do not find any QSO pair with a companion brighter than M1450(AB) < -26 mag within our 0.1-3.3 h^-1 cMpc search radius, in contrast to the serendipitous findings in the redshift range 4--5. However, a low fraction of such pairs at this luminosity and redshift is consistent with indications from present-day cosmological-scale galaxy evolution models. In turn, the incidence of L- and T-type brown dwarfs which occupy a similar colour space as z ~ 6 QSOs, is higher than expected, by a factor of 5 and 20, respectively.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
