1 / 35

Planck (and Supporting) Observations of Extragalactic “Point” Sources

Planck (and Supporting) Observations of Extragalactic “Point” Sources. Bruce Partridge, for Planck WG6 Haverford College, Haverford PA bpartrid@haverford.edu OUTLINE 1. Planck mission’s unique contributions 2. Radio sources: validation of ERCSC; counts and physical properties

olive
Télécharger la présentation

Planck (and Supporting) Observations of Extragalactic “Point” Sources

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. Planck (and Supporting) Observations of Extragalactic “Point” Sources Bruce Partridge, for Planck WG6 Haverford College, Haverford PA bpartrid@haverford.edu OUTLINE 1. Planck mission’s unique contributions 2. Radio sources: validation of ERCSC; counts and physical properties FIR emission from nearby galaxiesPrinceton-Planck, Feb, 23

  2. Unique Features of Planck Mission • All-sky surveys at 100-857 GHz are unique • Supporting, nearly simultaneous, ground-based observations at frequencies below & overlapping Planck bands • A variety of time scales probed • Point sources extracted from Galactic plane (esp. cold cores)

  3. Compare to WMAP At 30-100 GHz, roughly as many sources from 10 months as WMAP in 7 years (Gold et al. 2010) WMAP -- 471 Planck (at |b| > 5o) -- at 30 GHz -- 563 at 44 GHz -- 278 at 70 GHz -- 320 at 100 GHz ~ 800 Scores of these have supporting, approximately simultaneous ground-based measurements

  4. The ERCSC

  5. Again, compare to WMAP 7 yr. WMAP sources Planck sees Planck sources WMAP saw

  6. This talk…. Based on 5 Planck Early Papers • ERCSC paper astro-ph/1101.2041 • Statistical properties 1101.2044 • Extreme Radio Sources 1101.1721 • Blazars 1101.2047 • Nearby FIR galaxies 1101.2045 All source flux densities and positions from ERCSC Conscious decision not to “skim the cream;” plenty of science left. Open issues , further work, future plans… in italics

  7. Radio Sources: Validation of Planck Results Positional accuracy of ERCSC: LFI ..and HFI In both cases < 0.2 FWHM

  8. Radio Sources: Validation Flux density (possible only where catalogs or specific follow-up observations exist, e.g. 30 & 44 GHz) Shown here: Planck-VLA comparison of unresolved sources: note close agreement of slopes

  9. Radio Sources: Summary of Planck Findings 0. No huge surprises (unfortunately) 1. (Bright) sources at 30-143 (and generally 217) GHz are essentially all flat-spectrum radio sources (not dusty galaxies) 2. No obvious new category of extragalactic sources 2a. Few if any new, young GPS sources detected • Radio sources are mostly blazars 3a. And many of these are variable • Some sources have very extended, very flat spectra 4a. A challenge to jet acceleration models 5. Counts at 143 GHz fall a bit below models: relevant to ACT and SPT

  10. 1. Sources at 30-143 (and often 217) GHz are essentially all flat-spectrum radio sources (not dusty galaxies) The rule ---------> (Planck data in red) An exception: M82 -------> In bright Planck sources, synchrotron dominates. (“bump” at 100 GHz may be CO)

  11. Spectral indices show the same thing: Even at 217 --> 353 GHz, most sources have -----> synch. spectra… ….not thermal spectra ----->

  12. 2. No obvious new category of extragalactic sources >90% of Planck 30-70 GHz sources at |b| > 5o matched with cataloged radio sources with “sensible” flux densities. Rogues’ gallery of exceptions at 70 GHz:-- (note low galac. lat. for some) Will check out all unidentified sources at 30-70 & some at 100 & 143 GHz

  13. 2a. Few, young, GPS sources found One known young source A candidate (Planck data in red)

  14. 3. Most ERCSC sources, even with spectral peaks, are blazars Strongly beamed jet, general flat spectra In some, a spectral peak: “flaring shock-in-jet”? (Planck LFI data in red) (Planck HFI in blue)  ~simultaneous ground-based

  15. 3a. Many are variable Detected in both long-term monitoring (U. Michigan &Metsahovi) and in Planck & simultaneous ground-based work Effect of variability (esp.at 44 GHz with 2 widely spaced rows of detectors)

  16. 4. Many have remarkably flat spectra Variability can confuse results Note expected Follow-up observations underway  = 0.5 of some blazars turn-over Solid dots () are ~simultaneous ground-based observations

  17. 4. Many have remarkably flat spectra Two issues: When   0. electron energy spectrum is N(E)  E-1; rather extreme. Or is flat spectrum a cosmic conspiracy?

  18. Cosmic conspiracy -- many synch. self-absorbed components add up to a flat spectrum The basic idea… Evidence in one case, where Planck results are crucial

  19. But there are many cases where the spectrum really does look like a single, smooth power law Does this show simple Fermi acceleration (for which generally  ≤ -0.6) is inadequate?

  20. Complete SED of Blazars (plotting F) Synchrotron peak with synch. self-absorption cut-off Inverse Compton boosted emission at higher energy Are peak frequencies related?

  21. No obvious connection between synch and IC peak frequencies

  22. Nearby Starforming Galaxies: Summary of Planck Findings High S/N sources at 857, 545 & 343 GHz: • Evidence for cooler dust • In some cases, two component fits required (with lower T ~ 10-20 K) one instance ---->

  23. Nearby Starforming Galaxies: Summary of Planck Findings High S/N sources at 857, 545 & 343 GHz: 3. Planck sources fill gap in L-T plot between SMGs and very local galaxies Open squares & triangles: SMGs + local galaxies . Planck Contamination by AGN synchrotron emission?

  24. Statistical properties At |b| > 5o, most 30 GHz sources are extragalactic At |b| > 5o, 100 GHZ counts may be contaminated by Galactic emission (needs to be checked)

  25. Statistical properties Based on a sample selected at 30 GHz (therefore truly extragalactic) Findings: • Average spectral index steepens above 44 or 70 GHz 2. Counts at 143 & 217 match onto ACT & SPT counts well 3. But at these frequencies, counts fall below models (probably because of #1)

  26. Spectral steepening One example… These bright sources have slightly flatter spectra than AT20G sources (Murphy et al. 2010; Sajina et al. 2011)

  27. Statistics: pre-Planck 148 GHz counts

  28. Statistics: Counts (SPT, ACT & Planck) vs. models Models over-predict radio source counts by ~2

  29. (Some) Future Work -- with 3-4, not 1.6, Surveys Follow-up of ERCSC sources -- “unidentified” (Pearson, Chen or Partridge) -- sources with peaks in Planck frequency range (Rocha) Investigation of resolved sources -- M31regular & anomalous dust (Clements & Dickinson) -- low-z, classic radio galaxies; spectra of lobes (Israel) Further work on blazar SEDs (Lahteenmaki) Compiling variable sources (Rachen & Chen) Further work on flux density scales (Massardi & Partridge) Search for high-z “blobs” of sources (Montier) Initial work on polarization of sources (Caniego) Lensing enhancement of ERCSC counts around clusters (Chary)

More Related