Evolution of Cold Gas at 2 < z < 5: A Blind Search for H i and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN
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Evolution of Cold Gas at 2 < z < 5 : A Blind Search for H i and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN. / Gupta, N.; Srianand, R.; Shukla, G.; Krogager, J-K; Noterdaeme, P.; Combes, F.; Dutta, R.; Fynbo, J. P. U.; Hilton, M.; Momjian, E.; Moodley, K.; Petitjean, P.
In: Astrophysical Journal Supplement Series, Vol. 255, No. 2, 28, 08.2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Evolution of Cold Gas at 2 < z < 5
T2 - A Blind Search for H i and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN
AU - Gupta, N.
AU - Srianand, R.
AU - Shukla, G.
AU - Krogager, J-K
AU - Noterdaeme, P.
AU - Combes, F.
AU - Dutta, R.
AU - Fynbo, J. P. U.
AU - Hilton, M.
AU - Momjian, E.
AU - Moodley, K.
AU - Petitjean, P.
PY - 2021/8
Y1 - 2021/8
N2 - We present results from a spectroscopically blind search for associated and intervening H i 21 cm and OH 18 cm absorption lines toward 88 active galactic nuclei (AGN) at 2 2. The detection rate ( 1.6(-1.4)(+3.8) %) suggests a low covering factor of the cold neutral medium (CNM; T similar to 100 K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Ly alpha systems (DLAs), has comoving absorption path lengths of Delta X = 130.1 and 167.7 for HI and OH, respectively. The corresponding number of absorbers per unit comoving path length are 2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path similar to 9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of H I 21 cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z > 2.
AB - We present results from a spectroscopically blind search for associated and intervening H i 21 cm and OH 18 cm absorption lines toward 88 active galactic nuclei (AGN) at 2 2. The detection rate ( 1.6(-1.4)(+3.8) %) suggests a low covering factor of the cold neutral medium (CNM; T similar to 100 K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Ly alpha systems (DLAs), has comoving absorption path lengths of Delta X = 130.1 and 167.7 for HI and OH, respectively. The corresponding number of absorbers per unit comoving path length are 2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path similar to 9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of H I 21 cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z > 2.
KW - FOCUS IMAGING SPECTROGRAPH
KW - AFRICAN LARGE TELESCOPE
KW - LYMAN-ALPHA SYSTEMS
KW - QUASAR-GALAXY PAIRS
KW - DIGITAL SKY SURVEY
KW - 21-CM ABSORPTION
KW - CM ABSORPTION
KW - NEUTRAL HYDROGEN
KW - CENTIMETER ABSORPTION
KW - INTERSTELLAR-MEDIUM
U2 - 10.3847/1538-4365/ac03b5
DO - 10.3847/1538-4365/ac03b5
M3 - Journal article
VL - 255
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0067-0049
IS - 2
M1 - 28
ER -
ID: 276215239