Gamma rays from star- forming regions. Jürgen Knödlseder (IRAP, Toulouse) 1

Transcription

1 Gamma rays from star- forming regions Jürgen Knödlseder (IRAP, Toulouse) 1

2 Gamma- ray sources in star- forming regions Star forming regions as paracle accelerators Pulsars and wind nebulae Supernova remnants Wind- wind collisions Gas clouds 2

3 Emission mechanisms SNRs Starbursts Binaries PWNs Curvature Radiation Pulsars 3

4 AcceleraAon Physics Diffusive Shock AcceleraAon InducAon MagneAc reconnecaon 4

5 Observing gamma rays Fermi- LAT satellite H.E.S.S. MAGIC launched in MeV 300 GeV almost 1 m 2 effecave area sub- degree scale angular resoluaon VERITAS MILAGRO operaaonal since 200x (x = a few) 25 GeV 10 TeV about 10 6 m 2 effecave area < 0.1 scale angular resoluaon 5

6 Colliding Wind Binaries Eta Carinae Smith (HST, NASA) André Fonseca Silva (arasts view) Corcoran (RXTE) 6

7 Months 1-10 Colliding Wind Binaries Gamma ray observaaons Months GeV GeV Abdo et al. (2010) Some temporal variaaon (in paracular at high energies) No pronounced correlaaon with periastron passage H.E.S.S. non- detecaon at TeV energies (spectral cut- off) Have we detected the first colliding- wind binary? Abdo et al. (2012) 7

8 Gamma- ray pulsars Fermi- LAT inventory (certainly outdated) 8

9 Gamma- ray pulsars Fermi- LAT observaaons of young pulsars GeV characterisacs Generally (but not always), two peaks separated by ½ rotaaons Generally (but now always), gamma peak offset from radio peak Hard, exponenaally cut- off spectra at 1-3 GeV Crab (MAGIC) Aleksik et al. (2011) 9

10 Pulsar wind nebulae TevCat 10

11 Pulsar wind nebulae Synopsis Kathrin Valerius (NOW 2014) 11

12 Pulsar wind nebulae EvoluAon Kathrin Valerius (NOW 2014), adapted from Stefan Klepser (2013) 12

13 Pulsar wind nebulae TeV zoologie Young plerions Evolved systems SNR G relaavely compact or unresolved good spaaal match with X- rays pulsar close to TeV centre extended and ogen resolved (up to degree scales) pulsars offset / outside TeV PWN spectral sogening away from pulsar 13

14 Pulsars and their wind nebulae Link between pulsar and pulsar wind nebulae GeV pulsars TeV PWN Abdo et al. (2013) Primary galacac GeV & TeV source populaaon GeV & TeV emission from young pulsar / PWN populaaons (< 1 Myr) Pulsars ~ instantaneous power PWN ~ integrated power Klepser et al. (2013) 14

15 Supernova remnants RX J (H.E.S.S) RX J (Fermi+H.E.S.S.) Aharonian et al. (2007) Abdo et al. (2012) 15

16 Supernova remnants Evidence for the pion bump Fermi- LAT findings Strong evidence for hadronic gamma- ray emission Proton spectra sogen above ~10 GeV Ackermann et al. (2013) 16

17 Supernova remnants Hewim (5 th Fermi Symposium) 17

18 TeV emission from young stellar clusters? Westerlund 1 Pismis 22 W 43 W 49A Westerlund 2 Cygnus See Isabelle s talk 18

19 Fermi s bubbles See Roland Crocker s talk on Wednesday Selig et al. (arxiv: ) 19

20 Large Magellanic Cloud The Infrared View (Spitzer) Meixner (SAGE) 20

21 Large Magellanic Cloud The Gamma- Ray View GeV 8 80 GeV > 600 GeV MarAn et al (5 th Fermi Symposium) Komin et al (SAIP2014) CharacterisAcs 30 Doradus is brightest region in gamma rays Extended emission not filling the galaxy or following the gas A few hard (or high- energy) sources 21

22 0.8 8 GeV Large Magellanic Cloud PSR J First extragalacac gamma- ray pulsar Crab twin (giant spin down pulsar) Ten Ames more luminous than Crab in gamma rays MarAn et al (5 th Fermi Symposium) 22

23 Large Magellanic Cloud PSR J (PWN N157B) 8 80 GeV > 600 GeV MarAn et al (5 th Fermi Symposium) Komin et al (SAIP2014) Most powerful pulsar known H.E.S.S. source compaable with PWN N157B, but 100 Ames the Crab luminosity! (can be explained by strong IR fields in 30 Doradus region) Fermi- LAT indicates flat GeV spectrum. Physical connecaon? 23

24 8 80 GeV Large Magellanic Cloud SNR N132D MarAn et al (5 th Fermi Symposium) Brightest SNR in the LMC (2500 yr, interacang with cloud) Hard spectrum Marginally detected by H.E.S.S. for 200 hr of observaaons TransiAon between middle- aged and young SNR? 24

25 Other Galaxies SMC M31 M82 NGC 253 NGC 4945 NGC 1068 ev GeV TeV Large variety of galaxies detected (dwarf, normal spiral, starbursts) Emission believed to be dominated by cosmic- ray induced gamma- ray producaon Access to comparaave and populaaon studies Abdo et al. (2010), Abdo et al. (2010), Acciari et al. (2009), Acero et al. (2009), MarAn (2011) 25

26 Galaxies Spectral evoluaon? Ackermann et al. (2012) 26

27 Galaxies SFR GeV luminosity correlaaon Ackermann et al. (2012) 27

28 What comes next? Cherenkov Telescope Array Take home facts About 100 Cherenkov telescope located in two sites (South, North) 3 size- classes of telescopes to cover a broad energy range (LST, MST, SST) Tenfold improvement in sensiavity w/r to exisang telescopes Fivefold improvement in angular resoluaon w/r to exisang telescopes Unprecedented energy coverage An open observatory An internaaonal research infrastructure for the next decades 28

29 Some selected Science Prospects Unveiling the sources of GalacAc cosmic rays CTA will identify sources of Galactic Cosmic Rays by measuring the spectral and morphological signatures of hadronic particle acceleration XMM & CTA simulation Fermi & H.E.S.S. measurements Acero et al. (2011) H.E.S.S. measurements Aharonian (2013) 29

30 Some selected Science Prospects Understanding paracle escape and the evoluaon of SNRs CTA will detect the entire population of TeV-emitting Galactic supernova remnants (about 80 objects). If the Galaxy hosts a proton PeVatron, CTA should see it! mid-aged (~10000 yr) young ( yr) 30

31 Some selected Science Prospects Assessing the impact of cosmic rays on the GalacAc environment CTA will observe the leaking of cosmic rays from the sources into the interstellar environment, providing clues on cosmic-ray-propagation physics. CTA simulation Acero et al. (2013) 31

32 Some selected Science Prospects Understanding cosmic- ray physics in diverse environments CTA will probe cosmic ray physics in a large variety of environments, covering dwarf galaxies, normal galaxies and starburst galaxies. Galactic centre Aharonian et al. (2006) Fermi Abdo et al. (2010) Aharonian et al. (2009) Abdo et al. (2012) 32

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