CHITALS: Cold HI 21-cm Absorption Line Survey

CHITALS: Cold HI 21-cm Absorption Line Survey 2015 PHISCC Workshop: HI Surveys Get Real Rajeshwari Dutta (with R. Srianand & Neeraj Gupta) IUCAA 18 March, 2015 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 1 / 17

Cold Gas in & around low-z Galaxies Motivation: Understand CNM phase (T 100 K & n 1 cm 3 ) in ISM and CGM of low-z galaxies, trace redshift evolution of CNM Objective: Connect between H i 21-cm absorption and galaxy properties Method: H i 21-cm absorption survey of Quasar-Galaxy-Pairs (QGPs) Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 2 / 17

Low-z H i 21-cm absorption studies 21-cm absorption is an useful tool to study thermal state, parsec-scale structure, filling factor of cold neutral gas in ISM & CGM Nature of 21-cm absorption line systems still unclear (small number statistics, pre-selection biases, origin of absorbers,...) Low-z 21-cm absorption survey: detect associated galaxies, H i 21-cm emission, milliarcsecond-scale VLBI spectroscopy Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 3 / 17

Quasar Galaxy Pairs QGPs to probe cold gas in/around galaxies: Carilli & van Gorkom 1992, Gupta+ 2010, Borthakur+ 2011 Carilli & van Gorkom 1992 Gupta+2010 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 4 / 17

Sample Construction Largest sample of low-z QGPs ( 100): Cross-matching: FIRST (S(1.4GHz) > 50 mjy) SDSS-DR10 galaxies (z gal(phot) < 0.4) Galaxy on top of QSO Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 5 / 17

Sample Construction Largest sample of low-z QGPs ( 100): Cross-matching: FIRST (S(1.4GHz) > 50 mjy) SDSS-DR10 galaxies (z gal(phot) < 0.4) Galaxy on top of QSO Sub-sample of 46 QGPs at b 40 kpc (largest absorption-unbiased sample of low-z galaxies) Gupta+ 2013 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 5 / 17

Observations Optical: Radio: SDSS-DR10 SALT long-slit spectra ( 50 hrs) Galaxy z, SFR, stellar mass, virial radius & metallicity GMRT & VLA L-band ( 250 hrs) 3σ optical depth sensitivity τdv 0.1 km s 1 (dv = 5 km s 1 ) Spectral resolution 2 km s 1 Spectral coverage 1000 km s 1 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 6 / 17

SALT Spectra 8 J1254+0546 z gal=0.0246 8 J1457+0519 z gal=0.2198 J125422.19+054619.8 6 6 J145722.53+051921.8 4 4 2 J145722.40+051918.8 2 J125422.21+054610.4 0 6650 6700 6750 6800 6850 6900 6950 Observed Wavelength (Å) 0 8000 8050 8100 8150 8200 8250 Observed Wavelength (Å) 4 J1133+0015 z gal=0.0752, 0.0758 1.1 J1551+0713 z gal=0.1007 J113303.02+001549.0 3 2 J155121.13+071357.7 0.9 0.7 0.5 0.4 4700 4710 4720 4730 4740 4750 4760 4770 Observed Wavelength (Å) 1.1 J113302.01+001541.7 1 0 7030 7040 7050 7060 7070 7080 7090 7100 Observed Wavelength (Å) J155126+071352.4 0.9 0.7 0.5 0.4 6460 6470 6480 6490 6500 6510 Observed Wavelength (Å) Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 7 / 17

Probing ISM using multi-wavelength observations of QGP Srianand+2013 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 8 / 17

21-cm absorption from QGPs Galaxy on top of QSO (b = 5 kpc): Ca ii, Na i and H i 21-cm absorption at z = 0.1468 J143806.79+175805.4 Galaxy on top Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 9 / 17

21-cm absorption from QGPs Galaxy on top of QSO (b = 5 kpc): Ca ii, Na i and H i 21-cm absorption at z = 0.1468 J143806.79+175805.4 Galaxy on top f c N(H i) / T s = 8 10 19 cm 2 K 1 1.1 J1438+1758 21-cm absorption 1.2 SDSS 0.9 CaII λ3934 4500 4510 4520 4530 4540 4550 4560 Observed Wavelength (Å) 1.1 CaII λ3969 0.7 0.5-40 -20 0 20 40 Velocity Relative to z abs = 0.1468 (km s -1 ) NaI λ5891 0.9 6740 6750 6760 6770 6780 Observed Wavelength (Å) NaI λ5897 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 9 / 17

21-cm absorption from QGPs Two galaxies along sightline: foreground at z = 0.1007 (no 21-cm absorption) & background at z = 0.3291 (21-cm absorption) J155121.13+071357.7 J155126+071352.4 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 10 / 17

21-cm absorption from QGPs Two galaxies along sightline: foreground at z = 0.1007 (no 21-cm absorption) & background at z = 0.3291 (21-cm absorption) J155121.13+071357.7 J155126+071352.4 f c N(H i) / T s = 0.09 10 19 cm 2 K 1 J1551+0713 21-cm absorption SDSS 0 0.95 0.90 MgII λ2796 0.4 0.2 3700 3710 3720 3730 3740 Observed Wavelength (Å) MgII λ2803 5 0-40 -20 0 20 40 Velocity Relative to z abs = 0.32892 (km s -1 ) 0 0.95 CaII λ3934 0.90 5 0 5200 5220 5240 5260 5280 5300 Observed Wavelength (Å) CaII λ3969 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 10 / 17

21-cm absorption from QGPs J004121.53-014257.0 J004126.01-014315.6 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 11 / 17

21-cm absorption from QGPs J004121.53-014257.0 J004126.01-014315.6 A z = 0.01767 spiral galaxy at b = 25 kpc from an extended radio-loud QSO f c N(H i) / T s = 0.12 10 19 cm 2 K 1 for sightline A To be reobserved for better constraining the galaxy H i emission and absorption Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 11 / 17

A QGP with disparate H 2 and 21-cm absorption Both H 2 and 21-cm absorption simultaneously for the first time at z < 1 (Dutta+ 2015, MNRAS, 448, 3718) Chen+ 2005 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 12 / 17

A QGP with disparate H 2 and 21-cm absorption Both H 2 and 21-cm absorption simultaneously for the first time at z < 1 (Dutta+ 2015, MNRAS, 448, 3718) Chen+ 2005 Sub-DLA at z = 0.10115 shows strong H 2, C i and Na i absorption from one of the two components in HST/COS spectrum 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2-100 -50 0 50-100 -50 0 50-100 -50 0 50-100 -50 0 50 Velocity Relative to z abs = 0.10115 (km/s) 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2-100 -80-60 -40-20 0 20 40-100 -80-60 -40-20 0 20 40 Velocity Relative to z abs = 0.10115 (km/s) Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 12 / 17

A QGP with disparate H 2 and 21-cm absorption Both H 2 and 21-cm absorption simultaneously for the first time at z < 1 (Dutta+ 2015, MNRAS, 448, 3718) Chen+ 2005 Sub-DLA at z = 0.10115 shows strong H 2, C i and Na i absorption from one of the two components in HST/COS spectrum 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2-100 -50 0 50-100 -50 0 50-100 -50 0 50-100 -50 0 50 Velocity Relative to z abs = 0.10115 (km/s) 1.2 0.4 0.2 0.0-0.2 1.2 0.4 0.2 0.0-0.2-100 -80-60 -40-20 0 20 40-100 -80-60 -40-20 0 20 40 Velocity Relative to z abs = 0.10115 (km/s) Strong H 2 component shows log N(H 2) = 16.61 ± 0.05 and T 01 = 133 +33 22 K (Muzahid+ 2015) Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 12 / 17

A QGP with disparate H 2 and 21-cm absorption N(H i) = 1.8 10 18 T s/f c τdv (cm 2 ) Muzahid+ 2015 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 13 / 17

A QGP with disparate H 2 and 21-cm absorption N(H i) = 1.8 10 18 T s/f c τdv (cm 2 ) 50 Muzahid+ 2015 40 30 Our VLBA 1.4 GHz continuum image contains only 27% of arcsecond scale emission, extending over 131 pc at redshift of absorber MilliArc seconds 20 10 0-10 -20-30 -40-50 40 20 0-20 -40 MilliArc seconds Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 13 / 17

A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar+ 2001 using ATCA (M(H i) 2 10 9 M ) Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 14 / 17

A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar+ 2001 using ATCA (M(H i) 2 10 9 M ) No 21-cm absorption associated with the strong H 2 component either the N(H i) associated with this component is 50% of the total N(H i) or the gas covering factor is 0.27 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 14 / 17

A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar+ 2001 using ATCA (M(H i) 2 10 9 M ) No 21-cm absorption associated with the strong H 2 component either the N(H i) associated with this component is 50% of the total N(H i) or the gas covering factor is 0.27 Weak tentative 3σ 21-cm absorption coincident with the weaker H 2 component spin temperature of 90 K, at odds with the weakness of H 2, C i and Na i absorption in this component Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 14 / 17

A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar+ 2001 using ATCA (M(H i) 2 10 9 M ) No 21-cm absorption associated with the strong H 2 component either the N(H i) associated with this component is 50% of the total N(H i) or the gas covering factor is 0.27 Weak tentative 3σ 21-cm absorption coincident with the weaker H 2 component spin temperature of 90 K, at odds with the weakness of H 2, C i and Na i absorption in this component 25 hrs in VLA to obtain 3 times higher S/N and resolution 21-cm absorption spectrum Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 14 / 17

z gal N gal Sample of CHITALS Low-z galaxies (z 0.4, median z = 0.1) with b 40 kpc and median b = 15 kpc probe gas in optical disks of galaxies, extended H i disks, extraplanar or intra-group gas N gal 8 6 4 2 0 40 30 b (kpc) 20 10 0 0.0 0.1 0.2 0.3 0.4 0 1 2 3 4 5 6 Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 15 / 17

Sample of CHITALS Low-z galaxies (z 0.4, median z = 0.1) with b 40 kpc and median b = 15 kpc probe gas in optical disks of galaxies, extended H i disks, extraplanar or intra-group gas N gal 8 6 4 2 0 40 30 b (kpc) 20 10 0 0.0 0.1 0.2 0.3 0.4 z gal 0 1 2 3 4 5 6 N gal Wide range of galaxy luminosity and morphology (early- to late-type), with SDSS colour u r 5.0 and median u r = 2 important resource for understanding high-z galaxy evolution based on absorption line studies 6 5 4 N gal 3 2 1 0 1 2 3 4 5 u r Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 15 / 17

Summary & Upcoming Results CHITALS will be an unbiased systematic survey of 21-cm absorption from the largest sample of low-z galaxies H i 21-cm optical depth around low-z galaxies as function of stellar mass, virial radius and SFR Application to high-z 21-cm absorbers and future blind 21-cm absorption surveys 8 QGPs with 21-cm absorption detection till now Statistical results to follow Future follow-ups: HST/COS UV spectroscopy, VLBI imaging and spectroscopy Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 16 / 17

Rajeshwari Dutta (IUCAA) CHITALS 18 March, 2015 17 / 17