Dust and Molecules at high-z R. Srianand, IUCAA, PUNE
C OLLABORATORS : • Patrick Petitjean, IAP , France • Neeraj Gupta, ASTRON, Netherlands • Pasquier Noterdaeme, IAP , France • Cedric Ledoux, ESO, Chile • Sebastian Lopez,Universidad de Chile, Chile • Hadi Rahmani, IUCAA • Sowgat Muzahid, IUCAA R. Srianand, IUCAA, PUNE Dust Meeting-2011 1
P LAN OF THE T ALK : • Basic introduction to damped Lyman- α systems (DLAs) • Search in DLAs for – H 2 and HD absorption – CO molecule – 2175 ˚ A bump – DIBs • Summary R. Srianand, IUCAA, PUNE Dust Meeting-2011 2
QSO SPECTRUM: A BSORPTION LINES R. Srianand, IUCAA, PUNE Dust Meeting-2011 3
DLA S C ONTAIN GOOD AMOUNT OF Ω g : lookback time (Gyr) 0 2 4 6 7 8 9 10 11 12 1.5 1.0 −3 ) DLA ( × 10 Ω g 0.5 0.0 0 1 2 3 4 5 z Noterdaeme et al. 2009, A&A, 505, 1087 R. Srianand, IUCAA, PUNE Dust Meeting-2011 4
W IDE RANGE OF HEAVY ELEMENTS R. Srianand, IUCAA, PUNE Dust Meeting-2011 5
P ROPERTIES OF DLAS: H IGH Z DLA S AND LBG S Most of these have high metallicity absorbers − Moller et al., 2002 R. Srianand, IUCAA, PUNE Dust Meeting-2011 6
I NSITU STAR - FORMATION IN HIGH - Z DLA S 1.2 0.8 CII λ 1334 0.4 0.0 1.0 25 0.5 • yr -1 Mpc -3 ) 0.0 0.10 20 −0.5 F λ (10 −17 erg s −1 cm −2 Å −1 ) 1213.2 1214.8 1216.5 1218.2 15 ρ * ( M O . 10 0.01 5 SiIII weighted mean 0.0 0.2 0.4 0.6 0.8 1.0 0 log(1+z) 1200 1205 1210 1215 1220 1225 1230 Rest Wavelength (Å) Rahmani et al. 2010 R. Srianand, IUCAA, PUNE Dust Meeting-2011 7
P HOTO - DISSOCIATION REGIONS : R. Srianand, IUCAA, PUNE Dust Meeting-2011 8
H 2 MOLECULES : R. Srianand, IUCAA, PUNE Dust Meeting-2011 9
H 2 AND C I IN DLA S : R. Srianand, IUCAA, PUNE Dust Meeting-2011 10
S EARCH FOR H 2 IN DLA S : UVES SURVEY Petitjean et al. 2000; Ledoux et al. 2003; Srianand et al. 2005; Noterdaeme et al. 2008 & Srianand et al. 2011 R. Srianand, IUCAA, PUNE Dust Meeting-2011 11
M OTIVATION : UVES SURVEY • Quantify the H 2 fraction in DLAs • Use the rotational level population to infer the physical state of the gas • Establish the connection between C I and H 2 and get additional constraints on physical state of the gas. • Constraining the variation of fundamental constants. • Probing the thermal evolution of CMBR. • Obtaining HD/H 2 and providing independent constraints on Ω b R. Srianand, IUCAA, PUNE Dust Meeting-2011 12
R ESULTS OF OUR UVES SURVEY : • Out of 77 DLAs at z ≥ 1.8 only 13 show H 2 detection. • Molecular fraction: 5 × 10 − 7 and 0.1. (Diffuse gas!). • Molecular fraction: ≤ 10 − 5 in non-detections • H 2 detection is independent of H I column density • H 2 detection is more frequent in high metallicity and dusty DLAs. • T = 100-300 K, n H = 10 − 200 cm − 3 and G = few G 0 . • Good candidates for constraining ∆ µ/µ . • HD is detected in one case. D/H is consistent with WMAP constraints. • Photoionization models: most of the DLAs originate from low density hot gas. • 21-cm survey: The H 2 gas contains very small amount of N (H I ). The extent of this component is less than 10 pc. R. Srianand, IUCAA, PUNE Dust Meeting-2011 13
S EARCH FOR CO IN DLA S : • To detect translucent and molecular gas. • Automatic search for very strong C I absorption in the SDSS spectrum of QSOs. 45 strong systems found. • The expected CO bands are in high wavelength side of the Lyman- α emission from the QSOs so one can search for them at z ≥ 1 . 5 . • Detection of CO at z ≥ 2 will allow one to measure CO/H 2 directly at different environments. R. Srianand, IUCAA, PUNE Dust Meeting-2011 14
F IRST DETECTION OF CO IN A DLA AT HIGH - Z R. Srianand, IUCAA, PUNE Dust Meeting-2011 15
V OIGT PROFILE FITTING OF DIFFERENT J LEVELS : R. Srianand, IUCAA, PUNE Dust Meeting-2011 16
CO EXCITATION DIAGRAM R. Srianand, IUCAA, PUNE Dust Meeting-2011 17
CO/H 2 RATIO 100 10 −4 Translucent Translucent 10 10 −5 N(CO)/N(C 0 ) N(CO)/N(H 2 ) 1.0 10 −6 0.1 10 −7 Diffuse Diffuse 0.01 10 −8 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 f H2 f H2 R. Srianand, IUCAA, PUNE Dust Meeting-2011 18
T(CMBR) VS . Z 14 0 (1+z) T CMB TCMB( z ) = (2 . 725 ± 0 . 002) × (1 + z )1 − β • with β = − 0 . 007 ± 0 . 027 . 0 (1+z) T CMB (1− β ) 12 Following decaying dark energy models of Jetzer • et al. 2010, 10 T CMB (K) TCMB( z = 0) × (1 + z )3 γ − 1 TCMB( z ) = 8 γ ( m − 3Ω m ) + x (1 + z ) m − 3(Ω m − 1) 6 ( m − 3)Ω m 4 Where, γ = 4 / 3 , Ω m = 0 . 275 ± 0 . 015 and m=3( weff + 1 ) with weff = p/ρ . The best 2 fitted value is weff = − 0 . 996 ± 0 . 025 . 0.0 0.5 1.0 1.5 2.0 2.5 3.0 z Noterdaeme et al. 2011, A&AL, 526, L7 R. Srianand, IUCAA, PUNE Dust Meeting-2011 19
CO SURVEY : S TATUS • 16 bright candidates were observed with UVES and about 20 is being observed with X-SHOOTER. • Till now there are 7 CO detections. Whenever z ≥ 2 we are detecting very strong H 2 and HD molecules. • Typical detection limit of N(CO) is few times 10 13 cm − 2 . • 50% of the data yet to be analysed. • CO detections are all towards red objects not in SDSS because of color selection but for other reasons. • Strong C I absorbers allow us to probe the translucent gas at high-z. • X-SHOOTER spectra also allow us to search for associated emission from the absorbers. Srianand et al. 2008; Noterdaeme et al., 2009; 2010; 2011 R. Srianand, IUCAA, PUNE Dust Meeting-2011 20
2175 ˚ A F EATURES : R. Srianand, IUCAA, PUNE Dust Meeting-2011 21
QSO COMPOSITE SPECTRUM : R. Srianand, IUCAA, PUNE Dust Meeting-2011 22
2170 ˚ A DUST FEATURE TOWARDS J0850+5159 R. Srianand, IUCAA, PUNE Dust Meeting-2011 23
S IGNIFICANCE OF THE FEATURE : R. Srianand, IUCAA, PUNE Dust Meeting-2011 24
2170 ˚ A DUST FEATURE TOWARDS J0852+3432 R. Srianand, IUCAA, PUNE Dust Meeting-2011 25
S IGNIFICANCE OF THE FEATURE : R. Srianand, IUCAA, PUNE Dust Meeting-2011 26
GMRT SPECTRA : R. Srianand, IUCAA, PUNE Dust Meeting-2011 27
SED FITTING : R ESULTS • For J0850+5159 : – N (H I ) = (5.73 ± 1.10) × 10 21 cm − 2 – T s ∼ 190 +124 − 69 K • For J0852+3435 : – N (H I ) = 6.97 ± 1 . 30 × 10 21 cm − 2 – T s /f c = 536 +234 − 88 K. R. Srianand, IUCAA, PUNE Dust Meeting-2011 28
CO AND UV BUMP R. Srianand, IUCAA, PUNE Dust Meeting-2011 29
SDSS SAMPLE : • 9.7 µ m silicate feature is seen in the systems that show UV bump. (Kulkarni et al. 2011, ApJ, 726, 14) • ∼ 15 UV bump candidates. Most of them will be searched for CO using VLT. • 39 Mg II systems with bump are reported by Jiang et al. 2011, ApJ, 732, 110. • Estimation of redshift path length for dusty absorbers. R. Srianand, IUCAA, PUNE Dust Meeting-2011 30
DIB S AT HIGH - Z : R. Srianand, IUCAA, PUNE Dust Meeting-2011 31
DIB S IN DLA S : X-S HOOTER SPECTRA 30 25 F λ (10 −17 erg s −1 cm −2 Å −1 ) QSO composite J1135−0010 20 QSO composite, A V =0.11 15 10 5 0 400 600 800 1000 1200 1400 1600 Obs. wavelength (nm) R. Srianand, IUCAA, PUNE Dust Meeting-2011 32
QSO-G ALAXY P AIRS : GMRT MINI - SURVEY 1290 1300 1310 1320 1160 1180 1200 1220 1240 1260 1280 1150 1200 1250 37 06 25 50 31 35 51 08 50 20 45 30 15 40 DECLINATION (J2000) DECLINATION (J2000) DECLINATION (J2000) 25 35 10 20 30 05 25 15 00 20 10 15 05 55 08 21 55.5 55.0 54.5 54.0 53.5 53.0 52.5 52.0 08 50 00.0 49 59.5 59.0 58.5 58.0 57.5 57.0 56.5 56.0 55.5 12 28 49.0 48.5 48.0 47.5 47.0 46.5 RIGHT ASCENSION (J2000) RIGHT ASCENSION (J2000) RIGHT ASCENSION (J2000) 1120 1140 1160 1180 1200 1160 1180 1200 1220 63 32 46 03 21 55 44 DECLINATION (J2000) 50 DECLINATION (J2000) 45 42 40 40 35 38 30 36 25 34 20 32 15 11 10 28 27 26 25 24 23 22 21 12 42 00 41 59 58 57 56 55 54 RIGHT ASCENSION (J2000) RIGHT ASCENSION (J2000) Gupta et al. 2010 R. Srianand, IUCAA, PUNE Dust Meeting-2011 33
QSO-G ALAXY P AIRS : J124157.54+633241.6 R. Srianand, IUCAA, PUNE Dust Meeting-2011 34
QSO-G ALAXY P AIRS : DIB S 30 30 20 20 10 10 0 0 0 0 0.5 0.5 1 1 1.5 1.5 R. Srianand, IUCAA, PUNE Dust Meeting-2011 35
S UMMARY : • We are successful in detecting the basic molecules in DLAs under normal interstellar medium conditions. • Complex molecules are still elusive. May be due to colour selection of QSOs. New selection is needed. • 2175 ˚ A feature is detected at high-z. DIBs are still elusive for z ≥ 0 . 5 . • Blind radio survey will be helpful. R. Srianand, IUCAA, PUNE Dust Meeting-2011 36
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