Extreme gas properties in the most distant quasars

Maiolino, R.; Oliva, E.; Ghinassi, F.; Pedani, M.; Mannucci, F.; Mújica, R.; Juárez, Yectivani

doi:10.1051/0004-6361:20035704

Cited by 64 publications

(96 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many of these spectra were already partly presented in previous works (Maiolino et al 2003(Maiolino et al , 2004bJuarez 2009). The data reduction process is presented in these previous papers, and here we summarize only the instrumental setup.…”

Section: Spectroscopic Data and Samplementioning

confidence: 91%

The extinction law at high redshift and its implications

Gallerani

Maiolino

Juárez

et al. 2010

A&A

Self Cite

152

171

View full text Add to dashboard Cite

We analyze the optical-near infrared spectra of 33 quasars with redshifts 3.9 ≤ z ≤ 6.4 to investigate the properties of dust extinction at these cosmic epochs. The SMC extinction curve has been shown to reproduce the dust reddening of most quasars at z < 2.2; we investigate whether this curve also provides a good description of dust extinction at higher redshifts. We fit the observed spectra with synthetic absorbed quasar templates obtained by varying the intrinsic slope (α λ ), the absolute extinction (A 3000 ), and by using a grid of empirical and theoretical extinction curves. We find that seven quasars in our sample are affected by substantial extinction (A 3000 ≥ 0.8), and characterized by very steep intrinsic slopes (α λ ≤ −2.3). All of the individual quasars require extinction curve deviating from that of the SMC, with a tendency to flatten at λ ≤ 2000 Å (in the rest frame of the source). However, due to the uncertainties in the individual extinction curves the SMC is still (marginally) consistent with the data in most cases. We obtain a mean extinction curve at z > 4, both by performing a simultaneous fit of all quasars and by averaging the extinction curves inferred for individual quasars. In the case of broad absorption line quasars (which are generally more absorbed by dust and possibly in a younger evolutionary stage), the mean extinction curve deviates from the SMC at a confidence level ≥95%. The difference between extinction curves in quasars at z > 4 and in quasars at lower redshift is indicative of either a different dust production mechanism at high redshift, or a different mechanism for processing dust into the ISM. We suggest that the same transitions may also apply to normal, star-forming galaxies at z > 4. In particular, the observed change in the average spectral slope of galaxies at z > 4 may be partially ascribed to a variation in the extinction curve, rather than a lower dust content at high redshift. In this scenario, the extinction curve inferred at z > 4 would imply a cosmic star-formation corrected for dust attenuation a factor of ∼2 higher than estimated in the past.

show abstract

Section: Spectroscopic Data and Samplementioning

confidence: 91%

The extinction law at high redshift and its implications

Gallerani

Maiolino

Juárez

et al. 2010

A&A

Self Cite

152

171

View full text Add to dashboard Cite

show abstract

“…Recent simulations of mergers and quasar evolution show that during much of the lifetime of the quasar, it is heavily shrouded by gas with large column densities (e.g., Hopkins et al 2005). Observational support for this view comes from the discovery of a large number (four out of a sample of eight) of LoBALs in high-redshift quasars (Maiolino et al 2004).…”

Section: Implications For Quasar Populations and Evolutionmentioning

confidence: 99%

A Self‐consistent NLTE‐Spectra Synthesis Model of FeLoBAL QSOs

Casebeer¹,

Baron²,

Leighly³

et al. 2008

ApJ

View full text Add to dashboard Cite

We present detailed radiative transfer spectral synthesis models for the iron low ionization broad absorption line (FeLoBAL) active galactic nuclei (AGNs) FIRST J121442.3+280329 and ISO J005645.1À273816. Detailed non-LTE spectral synthesis with a spherically symmetric outflow reproduces the observed spectra very well across a large wavelength range. While exact spherical symmetry is probably not required, our model fits are of high quality, and thus very large covering fractions are strongly implied by our results. We constrain the kinetic energy and mass in the ejecta and discuss their implications on the accretion rate. Our results support the idea that FeLoBALs may be an evolutionary stage in the development of more ''ordinary'' QSOs.

show abstract

“…As one alternative, both classes of objects could be observed during a young phase of AGN evolution, characterized by smaller black hole masses and higher accretion rates (e.g. Pounds et al 1995;Mathur 2000;Yuan & Wills 2003;Maiolino et al 2004;Botte et al 2004). In fact, I Zw 1 is a NLS1 whose similarity with broad-absorption line QSOs has previously been noted.…”

Section: Nuclear Activity Of I Zwmentioning

confidence: 99%

The nearby QSO host I Zw 1: the stellar disk and adjacent objects

Scharwächter¹,

Eckart

Pfalzner

et al. 2007

A&A

View full text Add to dashboard Cite

Context. The relation between tidal interactions, starbursts, and the onset and/or fueling of active galactic nuclei (AGN) is a matter of debate. I Zw 1 is considered as the prototypical narrow-line Seyfert 1 galaxy (NLS1) and as one of the closest quasi-stellar objects (QSOs). With a clear spiral host and a small companion galaxy to the west, I Zw 1 is a possible example of minor-merger-related nuclear activity. Aims. This study investigates possible signs of a relation between merger process, star formation activity, and AGN properties in the case of I Zw 1. Methods. The morphology of I Zw 1 and nearby sources is investigated via high-resolution near-infrared (NIR) images. Color trends in the host galaxy of I Zw 1 are discussed by means of optical-to-NIR color composites. Long-slit spectra of the QSO nucleus of I Zw 1 and of the two nearby sources to the north and the west of the I Zw 1 disk are analyzed. Results. The data support the scenario of a tidal interaction between I Zw 1 and the small companion galaxy to the west. A concentration of blue color in the western part of the I Zw 1 host galaxy might be the manifestation of merger-induced star formation activity. Previous findings that the likely companion has an old evolved stellar population are substantiated by the new data. An extension to the west of the putative companion emerges as a separate source. The source to the north of the I Zw 1 disk is reconfirmed as a late-type foreground star. Lines in the nuclear K-band spectrum of I Zw 1 are discussed in comparison to data prior to this article and line fluxes are reported.

show abstract

Extreme gas properties in the most distant quasars

Cited by 64 publications

References 40 publications

The extinction law at high redshift and its implications

The extinction law at high redshift and its implications

A Self‐consistent NLTE‐Spectra Synthesis Model of FeLoBAL QSOs

The nearby QSO host I Zw 1: the stellar disk and adjacent objects

Contact Info

Product

Resources

About