Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-02-12
Astrophys.J. 617 (2004) 281-302
Astronomy and Astrophysics
Astrophysics
Accepted for publication in ApJ. Presentation improved and references added
Scientific paper
10.1086/424837
Strong intergalactic shocks are a natural consequence of structure formation in the universe. They are expected to deposit large fractions of their energy in relativistic electrons (xi_e~0.05 according to SNR observations) and magnetic fields (xi_B~0.01 according to cluster halo observations). We calculate the synchrotron emission from such shocks using an analytical model, calibrated with a hydrodynamical LCDM simulation. The resulting signal composes a large fraction of the extragalactic radio background (ERB) below 500 MHz. The associated angular fluctuations dominate the sky for frequencies nu<10 GHz and angular scales arcmin-deg (after a modest removal of point sources), provided that xi_e*xi_B>3*10^-4. The fluctuating signal is most pronounced for nu<500 MHz, dominating the sky even for xi_e*xi_B=5*10^-5. The signal will be easily observable by next generation radio telescopes such as LOFAR and SKA, and is marginally observable with present telescopes. It may be identified using cross-correlations with tracers of large scale structure, possibly even in existing <10 GHz CMB anisotropy maps and high resolution ~1 GHz radio surveys. Detection of the signal will provide the first identification of intergalactic shocks and of the WHIM, and gauge the unknown intergalactic magnetic field. We show that existing observations of the diffuse <500 MHz radio background are well fit by a simple, double-disk Galactic model, precluding a direct identification of the diffuse ERB. Modelling the frequency-dependent anisotropy pattern observed at very low (1-10 MHz) frequencies can disentangle the distributions of Galactic cosmic-rays, ionized gas and magnetic fields. Space missions such as ALFA will thus provide important insight into the structure and composition of our Galaxy (abridged).
Keshet Uri
Loeb Abraham
Waxman Eli
No associations
LandOfFree
Imprint of Intergalactic Shocks on the Radio Sky does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Imprint of Intergalactic Shocks on the Radio Sky, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Imprint of Intergalactic Shocks on the Radio Sky will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-84961