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Beyond COrE Workshop, Paris Picture: GALFACTS Collaboration.

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Presentation on theme: "Beyond COrE Workshop, Paris Picture: GALFACTS Collaboration."— Presentation transcript:

1 Beyond COrE Workshop, Paris Picture: GALFACTS Collaboration

2  Synchrotron Physics (Galactic)  Component separation for foregrounds  What can COrE tell us that we don’t know already from WMAP and Planck?  Current ground-based work  What about extragalactic low-frequency sources (AGN)? Beyond COrE Workshop, Paris

3  Cosmic ray leptons (electrons, mostly) › Origin › Propagation › Distribution  Magnetic Fields (at source) › Structure  Coherent/Ordered/Random › Intensity  Propagation effects › Faraday Rotation › Free-free absorption Beyond COrE Workshop, Paris

4  Supernova remnants prominent in Galactic synchrotron emission  Strong shocks  Pulsar winds Beyond COrE Workshop, Paris

5  First-order Fermi (e.g. Bell 1978): › N(E)  E −s, I  − , s = 2  +1 › s = (r+2)/(r − 1) › r = 4 for strong adiabatic shock: s = 2,  = 0.5 › r 2,  > 0.5 › r = 7 relativistic shock  s = 4/3,  = (Test particle)  Complicated (CR-dominated) › r >> 4 cooling shock  but fast particles don’t see this compression ratio Beyond COrE Workshop, Paris

6 VLA (Dyer et al 2009) Chandra (NASA/CXC)

7  Shock front Radio-X-ray: ›  = 0.50  0.02 › Decourchelle et al (2011)  X-ray synchrotron  = 1.5 › Cutoff in spectrum just below X-ray band › Highest-energy electrons ~ 100 TeV  Thin shock suggests r > 4  Barrel shape: › Efficient acceleration at parallel shocks?  Contrary to Bell model!  SN1006 has radial B-field Beyond COrE Workshop, Paris

8  Significant variation in SNR spectral indices  Pulsar Wind nebulae flatter, e.g. Crab  = 0.3  Balance between steepening spectrum of old material and injection of new material: › Young SNR (+radio SN) have steeper spectra. Beyond COrE Workshop, Paris

9  Low sensitivity in WMAP data at λ < 1.3 cm gives limited sky coverage  Note flat spectrum for Crab nebula  Mean β P ≈ −3.0 › Slightly flatter than at lower frequencies. (−3.1 in same regions)  Kogut et al (2007) claim detection of flattening from β P ≈ −3.2 to −3.0 from WMAP data alone… › Use smoothing from 7° to 18° › No allowance for pol. bias at 23 GHz: artifact? Beyond COrE Workshop, Paris (3-year WMAP data)

10  External galaxies show SR most intense in spiral arms  (M51 extreme case)  Highest fractional polarization in interarms › Field more ordered Beyond COrE Workshop, Paris

11  Milky Way also has distinct radio spiral arms  Consistent with arms in NE2001 model.  Cosmic ray analysis suggests CRs very smoothly distributed › e.g. Fermi: outer galaxy ≈ constant density  Major variation in B-field  Hammurabi code › Waelkens, Jaffe et al. › Sun et al (2008) › Jaffe et al (2010)  Fit: › 408 MHz I › 23 GHz p Beyond COrE Workshop, Paris NE2001 electron density contours

12  Hammurabi model:  B:  G › Jaffe et al (2010,2011)  Yet another wrinkle: › Laing (1980) › Not included in published Hammurabi analyses › too poorly constrained Beyond COrE Workshop, Paris

13  Ambient spectrum of CRs in ISM is steady state between injection & loss › radiative, diffusive, convective  Direct measurement in good agreement with inferred spectrum from synchrotron emission (B ~ 6  G)  Detailed modelling suggests injection spectrum with several breaks, very hard at low frequency (s ~ 1.6)  C.f. Orlando, Strong & Jaffe (2011)  Jaffe et al 2011: E 3 scaling  GALPROP prediction fitted to synchrotron data vs local e − spectrum. Beyond COrE Workshop, Paris

14  408 MHz I + 23 GHz P  Minimum intensity at mid latitudes  Synchrotron monopole: › Cosec|b|fit to Haslam map: zero level = 9.8 K (N), 10.1 K (S) › But already zeroed to  3 K › Would give negative intensity at faintest points › cf ARCADE2  Isotropic component! › Local bubble or halo? Beyond COrE Workshop, Paris

15  On large scale mostly dominated by coherent structures › Loops (local) › Fan (c. 1 kpc) › SNRs  Not a lot of scope for meaningful statistical analysis › higher resolution needed!

16 Beyond COrE Workshop, Paris  Only Loop I and top half of Loop III clear ???? ?

17  Polarization well organized across NGP  Fractional polarization low outside Spur: ~ 10% › Complex structure along LOS  Field in Spur follows outside field › Bright rim effect? Beyond COrE Workshop, Paris

18  Needed to do foreground science as well as for CMB!  Since Planck designed, Anomalous Microwave Emission discovered › Significant contributor GHz › Quite variable spectrum, peak GHz Beyond COrE Workshop, Paris

19  Synchro  Free-free  Spinning dust  Thermal dust  CMB  1° resolution Beyond COrE Workshop, Paris

20  rms 1°  E  B, r = 0.1  3.4% anomalous dust  10% thermal dust  artefacts at 100 & 217 GHz from CO lines QUIJOTE

21  Planck, after subtraction of templates for all major components  NB: template fit pretty good!  ESA press release Feb 2012 Beyond COrE Workshop, Paris  Fermi, E > 10 GeV  NASA press release Jan 2012

22  Existence of “haze” conclusively demonstrated  Interpretation: › Two components,  = 0.5 and  = 1  Implicit in template method › Region with single unusual  = 0.7 › Very hard to distinguish without ultra-precise measurements › Illustration assumes 2% errors for WMAP/Planck, except at > 50 GHz › Actual errors dominated by residuals from other foregrounds Beyond COrE Workshop, Paris

23  Synchrotron spectra are very smooth › Monoenergetic kernel › Nearly power-law electron distribution  Similarly › free-free › Spinning dust › Thermal dust  Synchrotron spectrum of mono- energetic electrons  Black body Beyond COrE Workshop, Paris

24  Power law is just an approximation…  …but a good one  The best- measured synchrotron sources are well fit by a 2 nd -order log-log polynomial over 2 decades of frequency Beyond COrE Workshop, Paris

25  Fermi shows electron spectrum really is smooth  NB: Emission frequency  E  Stay tuned for AMS2 results  Departures from power law expected at high E where propagtion time from nearest source ~ radiative lifetime  ~50 TeV?  Optical band! Assumes 6  G Jaffe et al (2011)

26  More frequencies: › Maybe we will have more frequency points than parameters to fit!  Better-defined frequencies because bands are narrower › Including significantly smaller colour correction › Hopefully more resources devoted to getting accurate bands in pre-launch calibration  High sensitivity: component discrimination depends on differences between adjacent bands › Easy to run out of SNR › Especially if bands are close together  BUT fundamentally, with all components smooth, subdividing bands rapidly stops giving new information  Very likely CMB+AME+Synch + Free-Free + dust is fundamentally ambiguous  NB: monopole uncertainty doesn’t help. Beyond COrE Workshop, Paris

27  Many surveys exist but quality uneven › Strong et al (2011) for an up-to-date list  Complications: › Below 300 MHz: free- free absorption, especially in the plane › Above 1 GHz: free- free emission › Below 5 GHz Faraday rotation › Above 10 GHz: AME Beyond COrE Workshop, Paris Guzmán et al 2011

28  Dipole arrays › Japan (Maeda et al 1999) › Chile (Alvarez et al 1997)  Merged map Guzmán et al (2011)  Spectral index vs 408 MHz Beyond COrE Workshop, Paris

29  Replacement for DRAO/Villa Elisa 21 cm survey  Fully sampled, 30′ beam  GHz  2048 channels › for RM Synthesis  I as well as Q U  South from Parkes › STAPS (PI Haverkorn)  Also ‘low’ band: MHz. Beyond COrE Workshop, Paris Wolleben et al (2010, ApJL)

30  Continuum Transit Survey with Arecibo L-Band Feed Array › 32% of sky  3 arcmin beam  300 MHz  2048 channels  Final maps will use GMIMS to recover large-scale structure Beyond COrE Workshop, Paris GALFACTS fields overlaid on Stockert Survey

31  2.3 GHz Southern-sky polarization survey with Parkes  9′ beam  Data collected, processing under way  Much less depolarized than 21 cm.  Figs from Carretti (2011) › ATNF Newsletter Beyond COrE Workshop, Paris

32  5 GHz all-sky survey  IQU, 48′ beam  Planck-like pseudo- correlation total power receiver combined with correlation polarimeter.  Telescope optimised to minimise sidelobes  Owens Valley (north)  Karoo (south) Beyond COrE Workshop, Paris

33  QUI JOint TEnerife experiment  GHz  Telescope recently installed on Teide  Aim to map ~ ¼ of sky at 15 GHz in full polarization Beyond COrE Workshop, Paris

34  Prior to WMAP, there were no large-area surveys from 6 cm to 100  m  Previously, pioneering this much new territory has yield unexpected phenomena › quasars, pulsars, X-ray binaries, Gamma-ray bursts, ULIRGs…  But WMAP and Planck LFI ERCSC show only expected blazar-type AGN  HFI point sources are also the expected SMGs  Deeper < 70 GHz with COrE-sized telescope will rapidly hit the confusion limit › LFI close to confusion at 30 GHz  Ground-based surveys already far deeper › and SKA is coming… Beyond COrE Workshop, Paris

35  Old questions: › What is the central engine? › How does it make relativistic jets? › How do jets propagate to Mpc scales? › How does the AGN population evolve cosmologically?  New questions › What do AGN do to their environment? › Regulate cluster cooling? › Provide entropy floor? › Use as Faraday probes to study growth of cosmic magnetic fields Beyond COrE Workshop, Paris

36

37 Guidetta et al (2011) Beyond COrE Workshop, Paris

38

39  Radio/X-ray interactions to probe dynamics  VLBI movies to probe dynamics  Variability  Large samples for statistics/rare cases  Polarization structure and wavelength- dependence to probe local and line-of- sight Faraday rotation › Must be spatially resolved! Beyond COrE Workshop, Paris

40 ALMA JVLA GBT Meerkat / SKA LMT ASKAP

41 Beyond COrE Workshop, Paris

42  COrE features: › many bands, high sensitivity, narrow(er) bands will all help untangle low frequency foregrounds › If frequency coverage extends  100 GHz › …and we avoid spectral lines!  BUT problem is fundamentally insoluable: not clear whether approximate solutions can be good enough to give interasting astrophysics.  COrE band is not of critical interest for synchrotron radiation  COrE measurements of AGN are not competitive with ground-based instruments. Beyond COrE Workshop, Paris


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