OCRA-p science projects

1. OCRA-p science projects Marcin Gawroński Bonn 14.III.2011

2. Observations with OCRA-p - two modes of observations (for bright and weaksources) - one primaryfluxdensitycalibrator (NGC 7027, Hafez et al., 2008) - correction of atmosphericabsorption is based on measurements of T_Sys at zenith and z=60 - gainelevationfunction is estimatedusing the series of NGC7027 measurements at differentelevations - fluxdensityerrors at level of 5-8% OCRA-p Bonn 14.III.2011 Marcin Gawroński

3. Modes of observations 1. Cross-scans (>100 mJy) OCRA-p Bonn 14.III.2011 Marcin Gawroński

4. Modes of observations 2. „On-off” Observations OCRA-p Bonn 14.III.2011 Marcin Gawroński

5. Modes of observations 2. „On-off” Observations Limits of the „on-off' method: - due to accuracy of pointing and trackingadditional position calibration is needed - cross-scans on nearbybrightsources (<4o, F30GHz > 150 mJy) - position calibrationevery 30-40 min - single „on-off' observation ~5 min, single cross-scan ~7 min OCRA-p Bonn 14.III.2011 Marcin Gawroński

6. Science projects - CJF CJF survey - test project, comparison of ourresults to other from the literature - 293 sourcesfromCaltech – Jodrell Bank Flat spectrum survey - S4.8 GHz > 350 mJy -  (1950)  35º - |b|  10º - 1.4-4.8 GHz>-0.5 (S) - observations in the „qscan” (cross-scan) mode (IV-VII 2005) - resultspublished in Lowe et al. 2007 OCRA-p Bonn 14.III.2011 Marcin Gawroński

7. Science projects - PNe Planetary nebulaesurveywith OCRA-p Aims: - test the spinning dustemissionhypothesis in the case of PNe - prepare a small sample of sourcewhich can be used as a future flux calibrators Observations: - 442 objectsfrom Acker et al. 1994 ( > -15º) - „blind” survey in the „qscan” mode (XII.2005 – V.2007) - detection of 93 PNe Results (Pazderska et al. 2009): - for 41 objects free-free emission models were calculated based on Siódmak & Tylenda (2001) - model fits well to observations and hence no need for additional emission mechanism OCRA-p Bonn 14.III.2011 Marcin Gawroński

8. Science projects - VSA Survey of sourcesfromVery Small Arrayfields Aims: - measure the flux densities of 121 sources in VSA fieldsselected at 15GHz with the Ryle telescope - investigate the spectral index distribution of weaksources - estimate the surfacedensity of sources Observations: - in the „on-off” mode (2007 -2009) - ~5 mesurements per source Results (Gawronski et al. 2010) - the estimated surface density of sources with F30GHz>10 mJy of 2.0  0.4/deg2 is in a good agreement with previous results (eg. Mason et al., 2010) - the proportion of steep spectrum sources increases with decreasing flux density (de Zotti et al., 2005) - no evidence for an additional population of sources with inverted spectra OCRA-p Bonn 14.III.2011 Marcin Gawroński

9. Science projects - VSA Spectral index distribution OCRA-p Bonn 14.III.2011 Marcin Gawroński

10. Science projects - VSA Variability of weak sources OCRA-p Bonn 14.III.2011 Marcin Gawroński

11. Science projects - CRATES Observations of the Combined Radio All-sky Targeted Eight-GHz Survey (CRATES) sample with OCRA-p Aims: - improve the knowledge about radio sources populations in the range ~2-200 Ghz - measure the flux densities of the selected subsample from CRATES (|b|  15º,1.4-4.8 Ghz>-0.5, 75º > >31º) Observations: - in both modes, for sources with f30_est>100 mJy „qscan” mode was used, for f30_est <100 mJy „on-off” mode was used - XI.2008 -VI.2010, ~6 mesurements per source Results (Peel et al. 2011): - 34 candidate GPS sources (5.4% objects from selected sample) - variability implies that simple source substraction strategies in CMB studies can be subject to considerable uncertainty - good corelation between the 30GHz flux densities and Fermi gamma-ray flux densities OCRA-p Bonn 14.III.2011 Marcin Gawroński

12. Science projects - CRATES OCRA-p Bonn 14.III.2011 Marcin Gawroński

13. Science projects - CRATES OCRA-p Bonn 14.III.2011 Marcin Gawroński

14. Science projects – SZ effect Observations of the Sunyaev–Zel'dovich (SZ) effect in Galaxy clusters Aims: - measure the SZ effect in well selected galaxy clusters sample - estimate the properties of IGM - investigate the cosmological evolution of GC Observations: - long integrations in the „on-off” mode - observations of trail field separated from the target fields by 20' in RA over the same range of hour angle after each cluster observation - 2006 – 2011 Results (Lancaster et al. 2007, Lancaster et al. 2011): - detections of the SZ effect in 21 most X-ray luminous clusters (4+17) - background source contamination is an important issue - estimated scaling relations between various cluster parameters are in good agreement with the self-similarity model (Morandi et al., 2007) OCRA-p Bonn 14.III.2011 Marcin Gawroński

15. Science projects – RS Oph International follow up of the RS Oph outburst in the radio part of the continuum - the latest outburst of the recurrent nova RS Oph was discovered on 12.II.2006 - observations were done in the on-off mode -MERLIN, VLBA, VLA, Effelsberg, GMRT, OCRA-p (1.4 – 30 GHz) - all data published in Eyres et al. 2009 and Eyres et al. 2010 OCRA-p Bonn 14.III.2011 Marcin Gawroński

16. Science projects – RS Oph Results OCRA-p Bonn 14.III.2011 Marcin Gawroński

17. Science projects – V407 Cyg OCRA-p follow up of the outburst of the symbiotic nova V407 Cyg - the outburst was discovered on 10.III.2010 - OCRA-p made a series of measurements during next 5 months - results were published in the Astronomer's Telegram #2511 & #2905 OCRA-p Bonn 14.III.2011 Marcin Gawroński