Distribution of the molecular absorption in front of the quasar B0218+357

Müller, S.; Guèlin, M.; Combes, F.; Wiklind, T.

doi:10.1051/0004-6361:20077310

Cited by 13 publications

(26 citation statements)

References 23 publications

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“…The 1 01 −0 00 para-H 2 CO transition, that was measured with even higher angular resolution (see Table 1), yields the same result. There is no hint of line absorption toward source B with a 3.1 km s −1 channel 3σ upper limit to the line-to-continuum ratio of 0.39 (see also Muller et al 2007). Table 2 indicates that the flux density of B0218+357 reaches a peak near 10 GHz.…”

Section: Formaldehyde Absorption Toward Image Amentioning

confidence: 99%

Redshifted formaldehyde from the gravitational lens B0218+357

Jethava

Henkel

Menten

et al. 2007

A&A

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Context. Little is known about individual molecular clouds at high redshifts. The gravitational lens toward B0218+357 offers the unique possibility to study cool moderately dense gas with high sensitivity and angular resolution in a cloud that existed half a Hubble time ago. Aims. This non-CO molecular multi-level study of a significantly redshifted cloud aims at a better definition of the physical properties of molecular gas in a kind of interstellar environment that is rarely studied in the Galaxy or in the nearby extragalactic space. Methods. Observations of the radio continuum and six formaldehyde (H 2 CO) lines were carried out with the VLA, the Plateau de Bure interferometer and the Effelsberg 100-m telescope. Results. Three radio continuum maps indicate a flux density ratio between the two main images, A and B, of ∼3.4 ± 0.2. Within the errors the ratio is the same at 8.6, 14.1, and 43 GHz. The 1 01 −0 00 line of para-H 2 CO is shown to absorb the continuum of image A. Large Velocity Gradient radiative transfer calculations are performed to reproduce the optical depths of the observed two cmwave "K-doublet" and four mm-wave rotational lines. These calculations also account for a likely frequency-dependent continuum cloud coverage. Confirming the diffuse nature of the cloud, an n(H 2 ) density of <1000 cm −3 is derived, with the best fit suggesting n(H 2 ) ∼ 200 cm −3 . The H 2 CO column density of the main velocity component is ∼5 × 10 13 cm −2 , to which about 7.5 × 10 12 cm −2has to be added to also account for a weaker feature on the blue side, 13 km s −1 apart. N(H 2 CO)/N(NH 3 ) ∼ 0.6, which is four times less than the average ratio obtained from a small number of local diffuse (galactic) clouds seen in absorption. The ortho-to-para H 2 CO abundance ratio is 2.0-3.0, which is consistent with the kinetic temperature of the molecular gas associated with the lens of B0218+357. With the gas kinetic temperature and density known, it is found that optically thin transitions of CS, HCN, HNC, HCO + , and N 2 H + (but not CO) will provide excellent probes of the cosmic microwave background at redshift z = 0.68.

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Section: Formaldehyde Absorption Toward Image Amentioning

confidence: 99%

Redshifted formaldehyde from the gravitational lens B0218+357

Jethava

Henkel

Menten

et al. 2007

A&A

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“…In the case of B 0218+357, molecular absorption is detected only toward one image of the quasar (Menten & Reid 1996;Muller et al 2007). Toward PKS 1830−211, molecular absorption is detected, however, for both of the bright and compact images, located one arcsecond apart on the north-east and south-west side, respectively, of the Einstein ring (Wiklind & Combes 1998;Muller et al 2006).…”

Section: Introductionmentioning

confidence: 97%

Molecules atz= 0.89

Müller

Beelen

Guèlin

et al. 2011

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We present the results of a 7 mm spectral survey of molecular absorption lines originating in the disk of a z = 0.89 spiral galaxy located in front of the quasar PKS 1830−211. Our survey was performed with the Australia Telescope Compact Array and covers the frequency interval 30-50 GHz, corresponding to the rest-frame frequency interval 57-94 GHz. A total of 28 different species, plus 8 isotopic variants, were detected toward the south-west absorption region, located about 2 kpc from the center of the z = 0.89 galaxy, which therefore has the largest number of detected molecular species of any extragalactic object so far. The results of our rotation diagram analysis show that the rotation temperatures are close to the cosmic microwave background temperature of 5.14 K that we expect to measure at z = 0.89, whereas the kinetic temperature is one order of magnitude higher, indicating that the gas is subthermally excited. The molecular fractional abundances are found to be in-between those in typical Galactic diffuse and translucent clouds, and clearly deviate from those observed in the dark cloud TMC 1 or in the Galactic center giant molecular cloud Sgr B2. The isotopic ratios of carbon, nitrogen, oxygen, and silicon deviate significantly from the solar values, which can be linked to the young age of the z = 0.89 galaxy and a release of nucleosynthesis products dominated by massive stars. Toward the north-east absorption region, where the extinction and column density of gas is roughly one order of magnitude lower than toward the SW absorption region, only a handful of molecules are detected. Their relative abundances are comparable to those in Galactic diffuse clouds. We also report the discovery of several new absorption components, with velocities spanning between −300 and +170 km s −1 . Finally, the line centroids of several species (e.g., CH 3 OH, NH 3 ) are found to be significantly offset from the average velocity. If caused by a variation in the proton-to-electron mass ratio μ with redshift, these offsets yield an upper limit | Δμ μ | < 4×10 −6 , which takes into account the kinematical noise produced by the velocity dispersion measured from a large number of molecular species.

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“…With respect to the detection of molecular absorption lines, the most striking differences are the continuum levels and the complexity of the absorption systems. B0218+357 hosts two molecular components separated by ∼13 km s −1 observed toward the south-western continuum image (Menten & Reid 1996;Jethava et al 2007;Muller et al 2007). Toward PKS 1830-211, weak molecular absorption is also measured toward the north-eastern radio continuum hotspot, displaced by -147 km s −1 from the dominant south-western absorption component (Wiklind & Combes 1998).…”

Section: Introductionmentioning

confidence: 99%

The kinetic temperature of a molecular cloud at redshift 0.9: ammonia in the gravitational lens PKS 1830–211

Henkel¹,

Braatz

Menten³

et al. 2008

A&A

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Context. Little is known about the structure of the interstellar medium and the nature of individual clouds in galaxies at intermediate redshifts. The gravitational lens toward PKS 1830-211 offers the unique possibility to study this interstellar gas with high sensitivity and angular resolution in a molecular cloud that existed half a Hubble time ago. Aims. This multi-line study aims at a better definition of the physical properties of a significantly redshifted cloud. Methods. Using the Green Bank Telescope (GBT), we searched for ammonia (NH 3 ) toward PKS 1830-211. Results. We have detected all ten observed metastable λ ∼ 2 cm ammonia lines. The (J, K) = (1, 1) to (10, 10) transitions, up to ∼1030 K above the ground state, were measured in absorption against the radio continuum of the lensed background source. The ammonia absorption appears to be optically thin, with absolute peak flux densities up to 2.5% of the total continuum flux density. Measured intensities are consistent with a kinetic temperature of ∼80 K for 80-90% of the ammonia column. The remaining 10-20% are warmer, with at least some of this gas reaching kinetic temperatures of > ∼ 600 K. Toward the south-western continuum source, the column density is N(NH 3 ) ∼ (5-10) × 10 14 cm −2 , which implies a fractional abundance of X(NH 3 ) ∼ (1.5-3.0) × 10 −8 . Similarities with a hot NH 3 absorption component toward the Sgr B2 region close to our Galactic center, observed up to the (18, 18) line, suggest that the Sgr B2 component also consists of warm diffuse low-density gas. The warm absorption features from PKS 1830-211 are unique in the sense that they originate in a spiral arm.

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Distribution of the molecular absorption in front of the quasar B0218+357

Cited by 13 publications

References 23 publications

Redshifted formaldehyde from the gravitational lens B0218+357

Redshifted formaldehyde from the gravitational lens B0218+357

Molecules atz= 0.89

The kinetic temperature of a molecular cloud at redshift 0.9: ammonia in the gravitational lens PKS 1830–211

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