J/ApJ/904/44 Evolution of C^IV^ absorbers. I. Absorber properties (Hasan+, 2020)
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Evolution of C^IV^ absorbers.
I. The cosmic incidence.
    Hasan F., Churchill C.W., Stemock B., Mathes N.L., Nielsen N.M.,
    Finlator K., Doughty C., Croom M., Kacprzak G.G., Murphy M.T.
   <Astrophys. J., 904, 44 (2020)>
   =2020ApJ...904...44H
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ADC_Keywords: QSOs; Spectra, optical; Spectra, ultraviolet; Spectra, infrared;
              Redshifts
Keywords: Quasar absorption line spectroscopy ; Circumgalactic medium ;
          Intergalactic medium ; Galaxy evolution ; High resolution
          spectroscopy

Abstract:
    We present a large high-resolution study of the distribution and
    evolution of C^IV^ absorbers, including the weakest population with
    equivalent widths W_r_<0.3{AA} . By searching 369 high-resolution,
    high signal-to-noise ratio spectra of quasars at 1.1<=z_em_<=5.3 from
    Keck/HIRES and VLT/UVES, we find 1268 C^IV^ absorbers with
    W_r_>~0.05{AA} (our ~50% completeness limit) at redshifts
    1.0<=z<=4.75. A Schechter function describes the observed equivalent
    width distribution with a transition from power-law to exponential
    decline at W_r_>~0.5{AA} . The power-law slope {alpha} rises by ~7%,
    and the transition equivalent width W* falls by ~20% from <z>=1.7 to
    3.6. We find that the comoving redshift path density, dN/dX, of
    W_r_>=0.05{AA} absorbers rises by ~1.8 times from z~4.0 to 1.3, while
    the W_r_>=0.6{AA} dN/dX rises by a factor of ~8.5. We quantify the
    observed evolution by a model in which dN/dX decreases linearly with
    increasing redshift. The model suggests that populations with larger
    W_r_ thresholds evolve faster with redshift and appear later in the
    universe. The cosmological Technicolor Dawn simulations at z=3-5
    overproduce the observed abundance of absorbers with W_r_<=0.3{AA}
    while yielding better agreement at higher W_r_. Our empirical linear
    model successfully describes C^IV^ evolution in the simulations and
    the observed evolution of W_r_>=0.6{AA} C^IV^ for the past ~12Gyr.
    Combining our measurements with the literature gives us a picture of
    C^IV^ absorbing structures becoming more numerous and/or larger in
    physical size over the last ~13Gyr of cosmic time (z~6-0).

Description:
    We have analyzed 369 high-resolution, high signal-to-noise ratio (S/N)
    quasar spectra obtained with the High Resolution Echelle Spectrometer
    (HIRES) spectrograph and the Ultraviolet and Visual Echelle
    Spectrograph (UVES) spectrograph from the Keck and Very Large
    Telescope (VLT) observatories, respectively. The wavelength coverage
    of the spectra spans approximately 3000-10000{AA}, though there is
    variable coverage in this range from spectrum to spectrum. (R=36000).

File Summary:
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 FileName    Lrecl  Records  Explanations
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ReadMe          80        .  This file
table1.dat      49      369  List of QSO spectra
table2.dat      67     1268  Data of C^IV^ absorber properties
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See also:
 J/A+A/283/759 : CIV QSO absorption systems (Petitjean+ 1994)
 J/ApJ/596/768 : Optical depths in 19 QSOs (Schaye+, 2003)
 J/A+A/473/791 : CIV absorption in DLAs and sub-DLAs systems (Fox+, 2007)
 J/ApJ/679/194 : Low-z intergalactic medium. III. (Danforth+, 2008)
 J/ApJ/690/20  : Models of the AGN and black hole populations (Shankar+, 2009)
 J/ApJ/708/868 : CIV candidates (Cooksey+, 2010)
 J/MNRAS/401/2715 : CIV column densities in z<2.5 QSOs (D'odorico+, 2010)
 J/MNRAS/422/3370 : Spatial variation in fine-structure constant (King+, 2012)
 J/ApJ/761/112 : High-redshift MgII absorption QSOs with FIRE (Matejek+, 2012)
 J/ApJ/755/89  : Metallicities of damped Ly{alpha} systems (Rafelski+, 2012)
 J/ApJ/763/37  : Metals in SDSS QSOs.I. 1.5<z<4.5 CIV absorbers (Cooksey+, 2013)
 J/MNRAS/435/1198 : z~6 QSOs CIV doublet absorption systems (D'Odorico+, 2013)
 J/ApJ/776/114 : MAGIICAT. I. MgII Absorber-Galaxy Catalog (Nielsen+, 2013)
 J/MNRAS/445/2061 : Absorption multiphase circumgalactic medium (Liang+, 2014)
 J/ApJ/815/91  : z<0.16 CIV absorbers from HST/COS QSO spectra (Burchett+, 2015)
 J/ApJS/221/32 : Narrow MgII absorption lines from SDSS-DR9Q (Chen+, 2015)
 J/AJ/150/111  : KODIAQ DR1 (O'Meara+, 2015)
 J/ApJ/833/283 : HI-selected Lyman limit systems metallicities (Lehner+, 2016)
 J/A+A/611/A76 : DLAS dust-corrected metallicity (De Cia+, 2018)
 J/ApJ/883/163 : OI abs. search in Keck & VLT spectra 199 QSOs (Becker+, 2019)
 J/MNRAS/488/1035 : AGN UV luminosity function (Kulkarni+, 2019)

Byte-by-byte Description of file: table1.dat
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 Bytes  Format Units  Label Explanations
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  1- 14 A14    ---    QSO   Quasar name in J2000 format (1)
 18- 22 F5.3   ---    z     [1.16/5.3] Quasar emission redshift
 26- 35 A10    ---    Inst  Quasar spectrum observation facility
 38- 42 I5     0.1nm  wmin  [2636/7648] Minimum wavelength CIV search space (2)
 45- 49 I5     0.1nm  wmax  [3302/9578] Maximum wavelength CIV search space (3)
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Note (1): QSO name taken from Veron-Cetty & Veron, 2001, VII/224.
Note (2): Blueward limit of the portion of the spectrum that is searched for
          C^IV^ absorbers, defined by Lya 1215 emission of the quasar
Note (3): Redward limit of the portion of the spectrum that is searched for
          C^IV^ absorbers, set at 5000km/s blueward of C^IV^ 1548 emission
          of the quasar.
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Byte-by-byte Description of file: table2.dat
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 Bytes  Format Units    Label Explanations
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  1- 14 A14    ---      QSO   Quasar name in J2000 format
 18- 24 F7.5   ---      z     [1.04/4.72] CIV absorber redshift
 28- 32 F5.3   0.1nm    W1548 [0.05/4.23] CIV 1548 rest-frame equivalent width
 36- 40 F5.3   0.1nm  e_W1548 [0.001/0.2] Uncertainty in W1548
     44 A1     ---    l_Naod  Upper limit flag for Naod
 48- 53 F6.3   [cm-2]   Naod  [13.1/15.5] log10 Apparent Optical Depth (AOD)
                               column density, atoms/cm^2^
 57- 60 F4.2   [cm-2] E_Naod  [0/0.1]? Upward uncertainty in Naod (1)
 64- 67 F4.2   [cm-2] e_Naod  [0.01/0.2]? Downward uncertainty in Naod
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Note (1): For upper limits the uncertainty are given as as blanks.
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History:
    From electronic version of the journal

References:
    Hasan et al.     Paper II : 2022ApJ...924...12H
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(End)                          Prepared by [AAS], Coralie Fix [CDS], 14-Mar-2022