A. J. Apponi

Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71 III.Rapid and correlated flux density variability from radio to sub-mm bands

Aims. The BL Lac object S5 0716+71 was observed in a global multi-frequency campaign to search for rapid and correlated flux density variability and signatures of an inverse-Compton (IC) catastrophe during the states of extreme apparent brightness temperatures. Methods. The observing campaign involved simultaneous ground-based monitoring at radio to IR/optical wavelengths and was centered around a 500-ks pointing with the INTEGRAL satellite (November 10−17, 2003). Here, we present the combined analysis and results of the radio observations, covering the cm- to sub-mm bands. This facilitates a detailed study of the variability characteristics of an inter- to intra-day variable IDV source from cm- to the short mm-bands. We further aim to constrain the variability brightness temperatures (TB) and Doppler factors (δ) comparing the radio-bands with the hard X-ray emission, as seen by INTEGRAL at 3−200 keV. Results. 0716+714 was in an exceptionally high state and different (slower) phase of short-term variability, when compared to the past, most likely due to a pronounced outburst shortly before the campaign. The flux density variability in the cm- to mm-bands is dominated by a ∼ 4d ay time scale amplitude increase of up to ∼35%, systematically more pronounced towards shorter wavelengths. The cross-correlation analysis reveals systematic time-lags with the higher frequencies varying earlier, similar to canonical variability on longer time-scales. The increase of the variability amplitudes with frequency contradicts expectations from standard interstellar scintillation (ISS) and suggests a source-intrinsic origin for the observed inter-day variability. We find an inverted synchrotron spectrum peaking near 90 GHz, with the peak flux increasing during the first 4 days. The lower limits to TB derived from the inter-day variations exceed the 10 12 K IC-limit by up to 3−4 orders of magnitude. Assuming relativistic boosting, our different estimates of δ yield robust and self-consistent lower limits of δ ≥ 5−33 – in good agreement with δVLBI obtained from VLBI studies and the IC-Doppler factors δIC > 14−16 obtained from the INTEGRAL data. Conclusions. The non-detection of S5 0716+714 with INTEGRAL in this campaign excludes an excessively high X-ray flux associated with a simultaneous IC catastrophe. Since a strong contribution from ISS can be excluded, we conclude that relativistic Doppler boosting naturally explains the apparent violation of the theoretical limits. All derived Doppler factors are internally consistent, agree with the results from different observations and can be explained within the framework of standard synchrotron-self-Compton (SSC) jet models of AGN.

L183 (L134N) revisited. III. The gas depletion

We present a detailed study of the gas depletion in L183 (= L134N) for a set of important species, namely, CO, CS, SO, N_2H+ and NH_3. We show that all these species are depleted at some level. This level seems to depend mostly on a density threshold rather than on dust opacity. Therefore UV shielding would not be a main factor in the triggering of depletion. Our data suggest that CO, CS and SO depletion happen at densities of ˜3 × 104 cm-3, while N_2H+b and NH_3 seem to deplete at densities close to 106 cm-3. The latter result is consistent with the Bergin & Langer (cite{Bergin97}, ApJ, 486, 316) polar (H_2O) ice case but not with the more recent models of Aikawa et al. (cite{Aikawa03}, ApJ, 593, 906). CS depletion occurs much below its (J:2-1)b critical density, (7 × 105 cm-3) and therefore makes this species unsuitable to study the density structure of many dark cloud cores. Based on observations made with the CFHT, the Iram 30-m and the ARO 12-m (formerly NRAO 12-m). Appendix A is only available in electronic form at http://www.edpsciences.org

L183 (L134n) revisited. II. The dust content

We present here a complete dust map of L183 (=L134N) with opacities ranging from A V = 3 to 150 mag. Five peaks are identified as being related to known molecular peaks and among these dust peaks two are liable to form stars. The main peak is a prestellar core with a density profile proportional to r -1 up to a radius of ~4500 AU and the northern peak could possibly be on its way to form a prestellar core. If true, this is the first example of the intermediate steps between cloud cores and prestellar cores during the quasi-static contraction. Additionally, the low dust temperature of the core reported in Pagani et al. ([CITE]) is confirmed, and the ISOPHOT data are shown to be inappropriate for finding such cores. In the inner core,

L183 (L134N) Revisited - I. The very cold core and the ridge

T_mathrm{dust} approx 7.5

Research Note On the frequency of the CS (J: 2

K and could be as low as 6.7 K.

\rightarrow

We report new 1.2 mm continuum observations of the L183 (=L134N) dark cloud with the MAMBO bolometer array at IRAM. Combined with ISOCAM and ISOPHOT data at 7 and 200 μ m, this new observation is not compatible with the results found by Ward-Thompson et al. (1994) with SCUBA and further analysed by Lehtinen et al. (2003) using ISOPHOT data. Only one bright core, with a northern elongation (the ridge) is detected. We show that this core has an average temperature

1) and (J: 5

T approx 7.6~{rm K} pm0.5

\rightarrow

K which is one of the coldest temperatures reported so far.

4) transitions

While conducting high signal-to-noise ratio (SNR) observations of multiple transitions and different isotopomers of CS, SO and CO towards L183 (also known as L134N), we found that the CS ( J : 2

On the frequency of the CS (J: 2

rightarrow