Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-06-02
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
Accepted in MNRAS. Revised to match the accepted version
Scientific paper
The detection of ionized bubbles around quasars in redshifted 21-cm maps is possibly one of the most direct future probes of reionization. We consider two models for the growth of spherical ionized bubbles to study the apparent shapes of the bubbles in redshifted 21-cm maps, taking into account the finite light travel time (FLTT) across the bubble. We find that the FLTT, whose effect is particularly pronounced for large bubbles, causes the bubble's image to continue to grow well after it's actual growth is over. There are two distinct FLTT distortions in the bubble's image: (i) its apparent center is shifted along the line of sight (LOS) towards the observer from the quasar; (ii) it's shape is anisotropic along the LOS. The bubble initially appears elongated along the LOS. This is reversed in the later stages of growth where the bubble appears compressed. The FLTT distortions are expected to have an impact on matched filter bubble detection where it is most convenient to use a spherical template for the filter. We find that the best matched spherical filter gives a reasonably good estimate of the size and the shift in the center of the anisotropic image. The mismatch between the spherical filter and the anisotropic image causes a 10 - 20% degradation in the SNR relative to that of a spherical bubble. We conclude that a spherical filter is adequate for bubble detection. The FLTT distortions do not effect the lower limits for bubble detection with 1000 hr of GMRT observations. The smallest spherical filter for which a detection is possible has comoving radii 24 Mpc and 33 Mpc for a 3-sigma and 5-sigma detection respectively, assuming a neutral fraction 0.6 at z \sim 8.
Bharadwaj Somnath
Choudhury Tirthankar Roy
Datta Kanan K.
Majumdar Suman
No associations
LandOfFree
The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps 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 The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The impact of anisotropy from finite light travel time on detecting ionized bubbles in redshifted 21-cm maps will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-513123