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Register a new userCO and Dust in PSS2322+1944 at a redshift of 4.12
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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.
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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+.
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.
Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts - that is, increased rates of star formation - in the most massive dark matter halos at early epochs. However, it remains unknown how soon after the Big Bang such massive starburst progenitors exist. The measured redshift distribution of dusty, massive starbursts has long been suspected to be biased low in redshift owing to selection effects, as confirmed by recent findings of systems out to redshift z~5. Here we report the identification of a massive starburst galaxy at redshift 6.34 through a submillimeter color-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40% of the baryonic mass. A maximum starburst converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn of cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.
A diverse range of dust attenuation laws is found in star-forming galaxies. In particular, Tress et al. (2018) studied the SHARDS survey to constrain the NUV bump strength (B) and the total-to selective ratio (Rv) of 1,753 star-forming galaxies in the GOODS-N field at 1.5<z<3. We revisit here this sample to assess the implications and possible causes of the correlation found between Rv and B. The UVJ bicolour plot and main sequence of star formation are scrutinised to look for clues into the observed trend. The standard boundary between quiescent and star-forming galaxies is preserved when taking into account the wide range of attenuation parameters. However, an additional degeneracy, regarding the effective attenuation law, is added to the standard loci of star-forming galaxies in the UVJ diagram. A simple phenomenological model with an age-dependent extinction (at fixed dust composition) is compatible with the observed trend between Rv and B, whereby the opacity decreases with the age of the populations, resulting in a weaker NUV bump when the overall attenuation is shallower (greyer). In addition, we compare the constraints obtained by the SHARDS sample with dust models from the literature, supporting a scenario where geometry could potentially drive the correlation between Rv and B
The article describes the biography and manifold contributions to research in mathematics of Mikhail Aleksandrovich Shubin.
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