1 / 15

Cold Gas in Cooling Flows

Cold Gas in Cooling Flows. Cooled or just cold?. Alastair Edge - Durham. Charlottesville June 1st 2003. 25 th December 1998. 10-15 clusters with >1000 M o yr -1 flows. Dozens of central galaxies from ROSAT Survey known to have strong optical line emission.

adanne
Télécharger la présentation

Cold Gas in Cooling Flows

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cold Gas in Cooling Flows Cooled or just cold? Alastair Edge - Durham Charlottesville June 1st 2003

  2. 25th December 1998 • 10-15 clusters with >1000 Moyr-1 flows • Dozens of central galaxies from ROSAT • Survey known to have strong optical • line emission • Only NGC1275 known to have cold gas • The gap between cold gas expected to • cold gas known has never been wider

  3. 26th December 1998 • The upgrade to the A-band receiver took place in December 1998 and offered enhanced sensitivity over A2. • The highest redshift cooling flows have CO(3-2) redshifted into the A-band. • The total deposited mass within the A3 beam in these systems should be high. • I obtained service observations to see….

  4. A bit like buses……… • Buoyed by the success with the JCMT the next logical step was looking for CO(1-0) with IRAM-30m • From three runs in 1999, 2000 and 2002, we made 20 CO(1-0) detections with IRAM • More CO(3-2), CO(4-3) and CO(5-4) data from CSO and JCMT • Derived molecular gas masses lie between • 109-1011.5M⊙ (=1-300 x 109)

  5. Is this just selection? • There are now 60 clusters with recent IRAM-30m data (Edge 2001, Salome & Combes 2003 and Edge etal in prep). • Of these, 24 are detected with the detection fraction strongly dependent on optical line flux. • The detected CO line width distribution is relatively narrow (200-400km s-1).

  6. Where is the gas? • The JCMT, IRAM-30m and CSO data are of limited resolution (15-30”). • Obtaining higher spatial resolution requires mm-interferometry. • Apply for Owens Valley time (OVRO) • Five clusters observed so far (Edge & Frayer 2003, submitted) • Implied column densities >1022cm-2

  7. Where there is gas, there is dust • From JCMT SCUBA observations of A1835 and A2390 it is clear that there is a significant mass of cool dust in cDs as found from FIR data from IRAS. • Using SCUBA we made two more detections (A1068 and RXJ0821+07) and Chapman etal 2002 detect Zw3146 and E1455+22.

  8. Gas-to-Dust Ratios • Using SCUBA and IRAS detections and limits we can determine gas-to-dust ratios using a fixed dust temperature. • Mean gas-to-dust ratio is 1825 (Tdust=40K) or 925 (Tdust=35K). These values are higher than Galactic values but bracket values for ULIRGs and starbursts.

  9. Widening the net with Richard Wilman • Recent UKIRT UIST IFU and VLT VIMOS IFU observations very promising! • Having obtained detailed information on the molecular and ionised Hydrogen in these galaxies, the obvious next step is to look for atomic Hydrogen at 21cm. • Search in higher redshift cooling flows

  10. Origin of the cold gas • NGC1275 exhibits a number of peculiar features that have been attributed to a recent merger. • Most of the other 24 CO-detected central cluster galaxies share the properties of NGC1275. • Is this a coincidence or telling us that there is a common origin to all of these features?

  11. It’s cooled • The simplest explanation of the cool molecular gas we detect is that it is the long-awaited `sink’ of gas. • With the radically `down-sized’ X-ray cooling flow deposition rates, it is possible that the 109-11.5 M⊙of molecular gas found is deposited gas that is yet to be formed into stars.

  12. Alternatives? • Can mergers with gas-rich galaxies supply enough gas often enough given the HI-deficiency found in clusters? • Is this the ISM of the central galaxy? • Why the close link to short central cooling times?

  13. 5 Year Plan…. • SIRTF - FIR spectroscopy and photometry to get other cooling lines (CII 158μm and OI 63μm) and dust masses two orders of magnitude better than IRAS+SCUBA. • SOFIA – sub-mm/FIR spectroscopy of • brightest objects. • More mm-interferometry from Plateau de Bure or CARMA

  14. Points for discussion • Links to optical line emission? • Why are the CO lines so narrow? • Why isn’t Cygnus-A detected? • What fraction of the stars in the central galaxy form from cooled gas? • Can we trace the growth of the `cold sink’ with look back time?

  15. Conclusions • No-one in the audience today can ever state in a paper that there is no evidence for cold molecular gas in cooling flows! • Even you, James.

More Related