CHITALS: Cold HI 21-cm Absorption Line Survey

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1 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, / 17

2 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, / 17

3 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, / 17

Borthakur+ 2011 Carilli & van Gorkom 1992 Gupta+2010

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

5 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, / 17

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

7 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, / 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.

4 0 6650 6700 6750 6800 6850 6900 6950 Observed Wavelength (Å) 0 8000 8050 8100 8150 8200 8250 Observed Wavelength

7 0.5 0.4 4700 4710 4720 4730 4740 4750 4760 4770 Observed Wavelength (Å) 1.1 J113302.01+001541.

8 SALT Spectra 8 J z gal= J z gal= J J J J Observed Wavelength (Å) Observed Wavelength (Å) 4 J z gal=0.0752, J z gal= J J Observed Wavelength (Å) 1.1 J Observed Wavelength (Å) J Observed Wavelength (Å) Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

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

10 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 = J Galaxy on top Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 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.

9 CaII λ3934 4500 4510 4520 4530 4540 4550 4560 Observed Wavelength (Å) 1.1 CaII λ3969 0.7 0.

11 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 = J Galaxy on top f c N(H i) / T s = cm 2 K J cm absorption 1.2 SDSS 0.9 CaII λ Observed Wavelength (Å) 1.1 CaII λ Velocity Relative to z abs = (km s -1 ) NaI λ Observed Wavelength (Å) NaI λ5897 Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

12 21-cm absorption from QGPs Two galaxies along sightline: foreground at z = (no 21-cm absorption) & background at z = (21-cm absorption) J J Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 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.

13 21-cm absorption from QGPs Two galaxies along sightline: foreground at z = (no 21-cm absorption) & background at z = (21-cm absorption) J J f c N(H i) / T s = cm 2 K 1 J cm absorption SDSS MgII λ Observed Wavelength (Å) MgII λ Velocity Relative to z abs = (km s -1 ) CaII λ Observed Wavelength (Å) CaII λ3969 Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

14 21-cm absorption from QGPs J J Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

21-cm absorption from QGPs J004121.53-014257.0 J004126.01-014315.6 A z = 0.

= 0.12 10 19 cm 2 K 1 for sightline A To be reobserved for better constraining the

15 21-cm absorption from QGPs J J A z = spiral galaxy at b = 25 kpc from an extended radio-loud QSO f c N(H i) / T s = 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, / 17

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

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 Sub-DLA at z = shows strong H 2, C i and Na i absorption from one of the two components in HST/COS spectrum Velocity Relative to z abs = (km/s) Velocity Relative to z abs = (km/s) Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 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.

18 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 Sub-DLA at z = shows strong H 2, C i and Na i absorption from one of the two components in HST/COS spectrum Velocity Relative to z abs = (km/s) Velocity Relative to z abs = (km/s) Strong H 2 component shows log N(H 2) = ± 0.05 and T 01 = K (Muzahid+ 2015) Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

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

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

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

22 A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar using ATCA (M(H i) 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, / 17

23 A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar using ATCA (M(H i) 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, / 17

24 A QGP with disparate H 2 and 21-cm absorption Searched for 21-cm absorption and emission by Kanekar using ATCA (M(H i) 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, / 17

25 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 b (kpc) Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

26 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 b (kpc) z gal 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 N gal u r Rajeshwari Dutta (IUCAA) CHITALS 18 March, / 17

27 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, / 17

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

Cold gas at high redshifts. R. Srianand Inter-University Center for Astronomy & Astrophysics, Pune - India

Cold gas at high redshifts. R. Srianand Inter-University Center for Astronomy & Astrophysics, Pune - India Cold gas at high redshifts R. Srianand Inter-University Center for Astronomy & Astrophysics, Pune - India Why cold gas? Stars are formed from the cold gas. IAS, Bangalore,Nov, 2009 1 Why cold gas? Physical