Narrow Absorption Line Systems Research Articles

Results of Monitoring the Dramatically Variable CivMini–Broad Absorption Line System in the Quasar HS 1603+3820

We present six new and two previously published high-resolution spectra of the quasar HS 1603+3820 (z_em = 2.542) taken over an interval of 4.2 years (1.2 years in the quasar rest frame). The observations were made with the High-Dispersion Spectrograph on the Subaru telescope and Medium-Resolution Spectrograph on the Hobby-Eberly Telescope. The purpose was to study the narrow absorption lines (NALs). We use time variability as well as coverage fraction analysis to separate intrinsic absorption lines, which are physically related to the quasar, from intervening absorption lines. By fitting models to the line profiles, we derive the parameters of the respective absorbers as a function of time. Only the mini-BAL system at z_abs ~ 2.43 (v_off ~ 9,500 km/s) shows both partial coverage and time variability, although two NAL systems possibly show evidence of partial coverage. We find that all the troughs of the mini-BAL system vary in concert and its total equivalent width variations resemble those of the coverage fraction. However, no other correlations are seen between the variations of different model parameters. Thus, the observed variations cannot be reproduced by a simple change of ionization state nor by motion of a homogeneous parcel of gas across the cylinder of sight. We propose that the observed variations are a result of rapid continuum fluctuations, coupled with coverage fraction fluctuations caused by a clumpy screen of variable optical depth located between the continuum source and the mini-BAL gas. An alternative explanation is that the observed partial coverage signature is the result of scattering of continuum photons around the absorber, thus the equivalent width of the mini-BAL can vary as the intensity of the scattered continuum changes.

Erratum: Chemical abundances in QSO host galaxies and environments from narrow absorption line systems

Erratum: Chemical abundances in QSO host galaxies and environments from narrow absorption line systems

Chemical abundances in QSO host galaxies and environments from narrow absorption line systems

We determined C, N and a-element relative abundances in the gas surrounding six quasi-stellar objects (QSOs) at an average redshift of z 2.4, by studying six narrow associated absorption systems in Ultraviolet Visual Echelle Spectrograph (UVES) high-resolution spectra. We found five systems with a metallicity (measured by C/H) consistent or above the solar value. The ionization structure observed in the associated systems is clearly different from that of the intervening ones, indicating that the associated systems are influenced by the strong UV flux from the QSO. There is a possible correlation (anticorrelation) between [N/C] ([Si/C]) and [C/H] of the studied associated systems, and [N/C]= 0 when [C/H]= 0. We have compared these observational results with the predictions of a model simulating the joint evolution of QSOs and their spheroidal hosts. The agreement turns out to be very good; in particular, the case envisaging massive haloes and high star formation rates recovers both the correlation between [N/C] and [C/H] and the anticorrelation for [Si/C] versus [C/H]. Narrow associated absorption systems prove to be powerful tracers of the chemical abundances in gas belonging to high-redshift spheroidal galaxies. The outflow of this same gas, triggered by the QSO feedback, is probably going to contribute to the early enrichment of the surrounding intergalactic medium. A larger sample, possibly increasing the number of ionization stages, chemical elements and the redshift range, would allow us to put firm constraints on detailed chemical evolution models of galaxies at high redshifts.

An Intrinsic Absorption Complex toward RX J1230.8+0115: Geometry and Photoionization Conditions

We present Hubble Space Telescope/Space Telescope Imaging Spectrograph and Far Ultraviolet Spectroscopic Explorer spectra of the quasar RX J1230.8+0115 (V = 14.4,z = 0.117). In addition to Galactic, Virgo, and intervening absorption, this quasar is host to a remarkable intrinsic absorption complex. Four narrow absorption line systems, strong in C IV, N V, and O VI, lie within 5000 km s-1 of the QSO redshift. Three of the systems appear to be line locked, two in N V and two in O VI, with the common system residing in between the other two (in velocity). All three systems show signs of an intrinsic origin—smooth windlike profiles, high ionization, and partial coverage of the central engine. The fourth system, which appears at the systemic redshift of the QSO, may originate from host galaxy or intervening gas. Photoionization analyses imply column densities in the range 19.1 < log N(H) < 21 and ionization parameters in the range -1.3 < log U < 0.3. Revisiting the issue of line locking, we discuss a possible model in the context of the accretion disk/wind scenario and point out several issues that remain for future simulations and observations.

Variability Tests for Intrinsic Absorption Lines in Quasar Spectra

Quasar spectra have a variety of absorption lines whose origins range from energetic winds expelled from the central engines to unrelated, intergalactic clouds. We present multiepoch, medium-resolution spectra of eight quasars at z ~ 2 that have narrow associated absorption lines (AALs, within ±5000 km s-1 of the emission redshift). Two of these quasars were also known previously to have high-velocity mini-broad absorption lines (mini-BALs). We use these data, spanning ~17 yr in the observed frame with 2-4 observations per object, to search for line-strength variations as an identifier of absorption that occurs physically near (intrinsic to) the central active galactic nucleus. Our main results are the following: Two out of the eight quasars with narrow AALs exhibit variable AAL strengths. Two out of two quasars with high-velocity mini-BALs exhibit variable mini-BAL strengths. We also marginally detect variability in a high-velocity narrow absorption line system, blueshifted ~32,900 km s-1 with respect to the emission lines. No other absorption lines in these quasars appeared to vary. The outflow velocities of the variable AALs are 3140 and 1490 km s-1. The two mini-BALs identify much higher velocity outflows of ~28,400 and ~52,000 km s-1. Our temporal sampling yields upper limits on the variation timescales from 0.28 to 6.1 yr in the quasar rest frames. The corresponding minimum electron densities in the variable absorbers, based on the recombination timescale, are ~40,000 to ~1900 cm-3. The maximum distances of the absorbers from the continuum source, assuming photoionization with no spectral shielding, range from ~1.8 to ~7 kpc.

On the Origin of Intrinsic Narrow Absorption Lines inz ≲ 1 QSOs

We present an exhaustive statistical analysis of the associated (Δvabs < 5000 km s-1), high-ionization (C IV, N V, O VI) narrow absorption line (NAL) systems in a sample of 59 QSOs defined from the Hubble Space Telescope (HST) QSO Absorption Line Key Project. The goals of the research were twofold: (1) to determine the frequency of associated NALs at low redshift and in low luminosity QSOs, and (2) to address the question of what QSO properties either encourage or inhibit the presence of associated NAL gas. To that end, we have compiled the QSO rest-frame luminosities at 2500 Å, 5 GHz, and 2 keV, spectral indices at 2500 Å and 5 GHz, the Hβ emission-line FWHM, and the radio core fraction at observed 5 GHz. In addition, we have measured the C IV emission-line FWHM. We find 17 associated NALs (16 selected by C IV and one selected by O VI) toward 15 QSOs, of which ~10 are statistically expected to be intrinsic. From a multivariate clustering analysis, we find that the QSOs group together (in parameter space) based primarily on radio luminosity, followed (in order of importance) by radio spectral index, C IV emission-line FWHM, and soft X-ray luminosity. We find that radio-loud QSOs that have compact radio morphologies, flat radio spectra [α(5 GHz) > -0.5], and mediocre C IV FWHM (≲6000 km s-1) do not have detectable associated NALs, down to Wr(C ) = 0.35 Å. We also find that broad absorption line (BAL) QSOs have an enhanced probability of hosting detectable NAL gas. In addition, we find that the velocity distribution of associated NALs is peaked around the emission redshifts rather than the systemic redshifts of the QSOs. Finally, we find only one strong NAL [Wr(C ) ≳ 1.5 Å] in our low-redshift sample. A comparison with previous higher redshift surveys reveals evolution in the number of strong NAL systems with redshift. We interpret these results in the context of an accretion disk model. We propose that NAL gas hugs the streamlines of the faster, denser, low-latitude wind, which has been associated with BALs. In the framework of this scenario, we can explain the observational clues as resulting from differences in orientation and wind properties, the latter presumably associated with the QSO radio properties.

Nuclear winds in active elliptical galaxies. II - Observational signatures

We discuss the possible observational signatures resulting from the interaction of a nuclear wind with an elliptical host galaxy. The ionization parameter in emission-line gas, deduced from spatially resolved spectral observations, will be a strong indicator of the nuclear wind as well as the possible pickup of stellar mass loss by the wind. If the wind is sufficiently luminous, galactic X-ray profiles will exhibit an extended flattening. Detailed study of individual objects will be necessary for conclusive evidence of nuclear winds. We find that nuclear winds are unlikely to cause the disruption of the radio jets in wide-angle tail radio galaxies. Previously proposed mechanisms whereby nuclear winds cause the formation of narrow absorption line systems or stellar shells are not likely to occur if the interstellar medium of the host elliptical galaxy is hot.

A catalog of absorption in the spectra of quasi-stellar objects

view Abstract Citations (63) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Catalog of Absorption in the Spectra of Quasi-stellar Objects Junkkarinen, V. ; Hewitt, A. ; Burbidge, G. Abstract This paper contains a compilation of basic information on QSO absorption systems. A total of 724 QSOs are listed in three tables. Table 1 contains 353 QSOs that have absorption-line systems with measured redshifts. The numerous Lyα forest systems based only on narrow hydrogen lines are excluded from Table 1. Absorption systems with multiple components are listed only once if all of the components fall within a span of 500 km s^-1^. A total of 862 systems with narrow metal lines which we consider to be reliably identified are listed in Table 1. Table 1 contains an additional 260 systems consisting of less certain systems, damped Lyα systems, and Lyman limit systems that have no detected narrow metal lines. In Table 2 we list 146 broad absorption line QSOs. Fifteen of these have narrow absorption line systems identified, and thus they also appear in Table 1. In Table 3 we give an inhomogeneous list of 240 QSOs in which absorption systems have been seen but not measured. Also shown are histograms of emission redshift, absorption redshift, and (1 + Z_em_)/( 1 + Z_abs_) for the reliably identified narrow metal line systems. Several selection effects are apparent in this collection of data. Publication: The Astrophysical Journal Supplement Series Pub Date: October 1991 DOI: 10.1086/191602 Bibcode: 1991ApJS...77..203J Keywords: Absorption Spectra; Astronomical Catalogs; Astronomical Spectroscopy; Quasars; Emission Spectra; Lyman Alpha Radiation; Red Shift; Astrophysics; GALAXIES: REDSHIFTS; LINE IDENTIFICATIONS; QUASARS full text sources ADS | data products NED (1454) SIMBAD (633) CDS (1) Related Materials (1) Erratum: 1992ApJS...81..409J

Spectroscopy of the QSO pair Q0028+003/Q0029+003

view Abstract Citations (37) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectroscopy of the QSO pair Q0028+003 / Q0029+003. Shaver, P. A. ; Boksenberg, A. ; Robertson, J. G. Abstract It is hypothesized that a prominent, narrow absorption line system discovered in the spectrum of Q0029+003, at a redshift of 1.7334, and only 190 km/sec from the emission line redshift of Q0028+003, may be due to a galaxy located in a cluster containing the latter QSO. Alternatively, the absorption line system may arise in a halo associated with Q0028+003 and extending at least 520 kpc, which is the projected separation of the two QSOs at this redshift. Publication: The Astrophysical Journal Pub Date: October 1982 DOI: 10.1086/183879 Bibcode: 1982ApJ...261L...7S Keywords: Absorption Spectra; Astronomical Spectroscopy; Galactic Clusters; Line Spectra; Quasars; Red Shift; Calcium; Galactic Nuclei; Magnesium; Spectral Energy Distribution; Spectral Line Width; Astronomy full text sources ADS | data products NED (7) SIMBAD (1) MAST (1)