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ATCA search for 21 cm emission from a candidate damped Ly-$α$ absorber at z = 0.101

Nissim Kanekar·Jayaram N Chengalur·Ravi Subrahmanyan·Patrick Petitjean
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Abstract

We report a deep search for 21 cm emission/absorption from the $z \sim 0.101$ candidate damped Lyman-$α$ system towards PKS 0439-433, using the Australia Telescope Compact Array (ATCA). The spectrum shows a weak absorption feature --- at the $3.3 σ$ level --- which yields a lower limit of 730 K on the spin temperature of the system. No HI emission was detected: the $3σ$ upper limit on the HI mass of the absorber is $2.25 \times 10^9 M_{\odot}$, for a velocity spread of $\sim 70$ km s$^{-1}$. The low HI mass and the high spin temperature seem to rule out the possibility that the absorber is a large gas-rich spiral galaxy.

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Nissim Kanekar, Jayaram N Chengalur, Ravi Subrahmanyan, Patrick Petitjean. 2000-12-04. ATCA search for 21 cm emission from a candidate damped Ly-$α$ absorber at z = 0.101. https://doi.org/10.1051/0004-6361%3A20000420

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