J/ApJ/800/7 Physical conditions of high redshift DLAs (Neeleman+, 2015) ================================================================================ Probing the physical conditions of atomic gas at high redshift. Neeleman M., Prochaska J.X., Wolfe A.M. =2015ApJ...800....7N ================================================================================ ADC_Keywords: QSOs ; Redshifts ; Abundances ; Spectroscopy ; Interstellar medium Keywords: galaxies: abundances; galaxies: evolution; galaxies: ISM; ISM: atoms; evolution; quasars: absorption lines Abstract: A new method is used to measure the physical conditions of the gas in damped Ly{alpha} systems (DLAs). Using high-resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper and lower fine-structure levels of the ground state of C^+^ and Si^+^. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5% of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ~100/cm3 and temperatures below 500K. We further find that the typical pressure of DLAs in our sample is log(P/k_B_)=3.4(K/cm3), which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsecs. We show that the majority of the systems are consistent with having densities significantly higher than expected for a purely canonical warm neutral medium, indicating that significant quantities of dense gas (i.e., n_H_>0.1/cm3) are required to match observations. Finally, we identify eight systems with positive detections of Si II*. These systems have pressures (P/k_B_) in excess of 20000K/cm3, which suggest that these systems tag a highly turbulent ISM in young, star-forming galaxies. Description: Data are taken from the high-resolution spectrograph (HIRES) on the Keck I telescope, which resulted in spectra with a typical resolution of ~8km/s. We further require that at least one of the transitions of both levels of the C^+^ and Si^+^ are clear of any forest lines or interloping features. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 101 80 Fine structure damped Ly{alpha} system (DLA) sample table2.dat 93 80 Results of SiII* and CII* technique -------------------------------------------------------------------------------- See also: VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010) II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/MNRAS/435/482 : DLA system from SDSS DR5 (Jorgenson+, 2013) J/ApJ/769/54 : Spectroscopy of DLA systems (Neeleman+, 2013) J/ApJ/755/89 : Metallicities of damped Ly{alpha} systems (Rafelski+, 2012) J/ApJS/171/29 : UCSD/Keck DLA Abundance Database (Prochaska+, 2007) J/ApJ/649/L61 : SDSS J155810.16-003120.0 abundances (O'Meara+, 2006) J/PASP/118/1077 : Metal-strong damped Ly{alpha} systems (Herbert-Fort+, 2006) J/ApJ/635/123 : The SDSS-DR3 damped Ly{alpha} survey (Prochaska+, 2005) J/ApJS/145/329 : Millennium Arecibo 21-cm Survey (Heiles+, 2003) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 --- Seq [1/80] Running sequence number of the DLA 4- 14 A11 --- QSO QSO name 16- 21 F6.4 --- zabs [1.6/4.9] Absorption redshift of DLA 23- 27 F5.2 [cm-2] NHI [20.3/22.1] Log of the hydrogen column density 29- 32 F4.2 [cm-2] e_NHI [0.05/0.2] Error in NHI 34- 38 F5.2 [Sun] [M/H] [-2.6/-0.1] Log of metal "M" to hydrogen number abundance 40- 43 F4.2 [Sun] e_[M/H] [0.05/0.5] Error in [M/H] 45- 46 A2 --- M Ion used for metallicity determination (O, S, Fe, Si or Zn) 48 A1 --- l_NCIIs Limit flag on NCIIs 50- 54 F5.2 [cm-2] NCIIs [12.5/15.7] Log of column density of CII* 55 A1 --- f_NCIIs [*] * = fitted using VPFIT (1) 57- 60 F4.2 [cm-2] e_NCIIs [0.01/0.2]? Error in NCIIs 62 A1 --- l_NSiIIs Limit flag on NSiIIs 64- 68 F5.2 [cm-2] NSiIIs [11/13.7] Log of column density of SiII* 70- 73 F4.2 [cm-2] e_NSiIIs [0.02/0.2]? Error in NSiIIs 75 A1 --- l_NSiII Limit flag on NSiII 77- 81 F5.2 [cm-2] NSiII [13.3/16.6] Log of column density of SiII 82 A1 --- f_NSiII [*] * = fitted using VPFIT (1) 84- 87 F4.2 [cm-2] e_NSiII [0.01/0.5]? Error in NSiII 89 A1 --- N13 [NY] Part of the sample of Neeleman et al. 2013, J/ApJ/769/54 91-101 A11 --- Ref Reference (2) -------------------------------------------------------------------------------- Note (1): VPFIT is the Voigt profile fitting program (http://www.ast.cam.ac.uk/~rfc/vpfit.html) Note (2): Reference as follows: 1 = Lu et al. (1996ApJS..107..475L); 2 = Prochaska & Wolfe (1997ApJ...487...73P); 3 = Lu et al. (1998AJ....115...55L); 4 = Prochaska & Wolfe (1999ApJS..121..369P); 5 = Petitjean et al. (2000A&A...364L..26P); 6 = Prochaska & Wolfe (2000ApJ...533L...5P); 7 = Prochaska et al. (2001ApJS..137...21P); 8 = Ledoux et al. (2003MNRAS.346..209L); 9 = Prochaska & Wolfe (2002ApJ...566...68P); 10 = Prochaska et al. (2003ApJ...595L...9P); 11 = Dessauges-Zavadsky et al. (2004A&A...416...79D); 12 = Khare et al. (2004ApJ...616...86K); 13 = Ledoux et al. (2006A&A...457...71L); 14 = O'Meara et al. (2006, J/ApJ/649/L61); 15 = Herbert-Fort et al. (2006, J/PASP/118/1077); 16 = Dessauges-Zavadsky et al. (2007A&A...470..431D); 17 = Prochaska et al. (2007, J/ApJS/171/29); 18 = Wolfe et al. (2008ApJ...681..881W); 19 = Jorgenson et al. (2010ApJ...722..460J); 20 = Kaplan et al. (2010PASP..122..619K); 21 = Rafelski et al. (2012, J/ApJ/755/89); 22 = Kulkarni et al. (2012ApJ...749..176K); 23 = Berg et al. (2013MNRAS.434.2892B); 24 = This Work; 25 = Berg et al. (2015PASP..127..167B); -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 --- Seq [1/80] Running sequence number of the DLA 4- 14 A11 --- QSO QSO name 16- 21 F6.4 --- zabs [1.6/4.9] Absorption redshift of DLA 23- 26 F4.1 [cm-3] b1NH The 1{sigma} lower limit to log(HI density) 28- 30 F3.1 [cm-3] B1NH The 1{sigma} upper limit to log(HI density) 32- 35 F4.1 [cm-3] b2NH The 2{sigma} lower limit to log(HI density) 37- 39 F3.1 [cm-3] B2NH The 2{sigma} upper limit to log(HI density) 41- 44 F4.1 [cm-3] b1Ne The 1{sigma} lower limit to log(electron density) 46- 49 F4.1 [cm-3] B1Ne The 1{sigma} upper limit to log(electron density) 51- 54 F4.1 [cm-3] b2Ne The 2{sigma} lower limit to log(electron density) 56- 59 F4.1 [cm-3] B2Ne The 2{sigma} upper limit to log(electron density) 61- 63 F3.1 [K] b1T The 1{sigma} lower limit to log(temperature) 65- 67 F3.1 [K] B1T The 1{sigma} upper limit to log(temperature) 69- 71 F3.1 [K] b2T The 2{sigma} lower limit to log(temperature) 73- 75 F3.1 [K] B2T The 2{sigma} upper limit to log(temperature) 77- 80 F4.1 [K/cm3] b1P/k The 1{sigma} lower limit to log(pressure/k_B_) 82- 84 F3.1 [K/cm3] B1P/k The 1{sigma} upper limit to log(pressure/k_B_) 86- 89 F4.1 [K/cm3] b2P/k The 2{sigma} lower limit to log(pressure/k_B_) 91- 93 F3.1 [K/cm3] B2P/k The 2{sigma} upper limit to log(pressure/k_B_) -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jun-2015