Optical and X-ray properties of the RIXOS active galactic nuclei -- I.: The continua

Puchnarewicz, E. M.; Mason, K. O.; Romero-Colmenero, E.; Carrera, Francisco J.; Hasinger, G.; McMahon, R. G.; Mittaz, J. P. D.; Page, M. J.; Carballo, R.

doi:10.1093/mnras/281.4.1243

Cited by 30 publications

(59 citation statements)

References 45 publications

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“…In the plot we show the BCES(Y j X ) (Akritas & Bershady 1996) linear fit to the full combined data sets, À HR ¼ (0:54 AE 0:15) UV þ (2:07 AE 0:13). A similar correlation of with soft X-ray spectral slope was found by Puchnarewicz et al ( 1996) using ROSAT data. They interpreted the correlation as arising from absorption by dusty gas on the intrinsic opticalY throughYX-ray continuum, which makes the optical spectrum redder and the X-ray spectrum harder, and our data are consistent with that scenario extended into the hard X-ray regime.…”

Section: Correlations Between X-ray and Optical Propertiessupporting

confidence: 82%

ChandraObservations of Red Sloan Digital Sky Survey Quasars

Gallagher¹,

Richards²,

Alexander³

et al. 2006

Astron J

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We present short Chandra observations of 12 bright (i < 18) z em $ 1:5 quasars from the Sloan Digital Sky Survey chosen to have significantly redder optical colors than most quasars at the same redshift. Of the five quasars with optical properties most consistent with dust reddening at the quasar redshift, four show indirect evidence of moderate X-ray absorption (inferred N H $ 10 22 cm À2 ) with a dust-to-gas ratio <1% of the SMC value. The remaining seven objects show no evidence for even moderate intrinsic X-ray absorption. Thus, while optically red quasars are marginally more likely to show signatures of X-ray absorption than optically selected quasars with normal colors, dust-reddened type 1 active galactic nuclei (as opposed to fully obscured type 2 active galactic nuclei) are unlikely to contribute significantly to the remaining unresolved hard X-ray background. The red quasar population includes objects with intrinsically red continua, as well as objects with dust-reddened continua. Improved sample selection is thus needed to increase our understanding of either subpopulation. To identify dust-reddened quasars likely to exhibit X-ray absorption, some measure of spectral curvature is preferable to simple cuts in observed or relative broadband colors.

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Section: Correlations Between X-ray and Optical Propertiessupporting

confidence: 82%

ChandraObservations of Red Sloan Digital Sky Survey Quasars

Gallagher¹,

Richards²,

Alexander³

et al. 2006

Astron J

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“…In order to investigate whether or not this value is systematically di †erent between NLS1Ïs and BLS1Ïs, we compare of 10 NLS1Ïs2 and 28 BLS1Ïs3 a ox taken from the sample of Walter & Fink (1993). It is noted that the values of for the sample of Walter & Fink (1993) a ox are slightly di †erent from those described in equation (1) because they measured the optical continuum Ñux at 2675 not at 2500 this leads to a di †erence of 0.02 in (see Ó, Ó: a ox Puchnarewicz et al 1996). The average spectral indices and 1 p deviations for the NLS1Ïs and the BLS1Ïs are [1.31^0.16 and [1.36^0.24, respectively.…”

Section: Observational Propertiesmentioning

confidence: 93%

“…The average for optically seleca ox ted radio-quiet AGNs is (Zamorani et al 1981 Puchnarewicz et al (1996), a ox whose sample is an X-rayÈselected one, is harder than the others : [1.14^0.18. In order to investigate whether or not this value is systematically di †erent between NLS1Ïs and BLS1Ïs, we compare of 10 NLS1Ïs2 and 28 BLS1Ïs3 a ox taken from the sample of Walter & Fink (1993).…”

Section: Observational Propertiesmentioning

confidence: 99%

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The Narrow‐Line Region of Seyfert Galaxies: Narrow‐Line Seyfert 1 Galaxies versus Broad‐Line Seyfert 1 Galaxies

Nagao

Murayama

Taniguchi

2001

ApJ

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It is known that the spectral energy distribution (SED) of the nuclear radiation of narrow-line Seyfert 1 galaxies (NLS1Ïs) has di †erent shapes with respect to that of ordinary broad-line Seyfert 1 galaxies (BLS1Ïs) particularly in X-ray wavelengths. This may cause some di †erences in the ionization degree and the temperature of gas in narrow-line regions (NLRs) between NLS1Ïs and BLS1Ïs This paper aims to examine whether or not there are such di †erences in the physical conditions of NLR gas between them. For this purpose, we have compiled the emission-line ratios of 36 NLS1Ïs and 83 BLS1Ïs from the literature. Comparing these two samples, we have found that the line ratios of, which represent the ionization degree and the gas temperature respectively, are statistically indistinguishable between NLS1Ïs and BLS1Ïs. Based on new photoionization model calculations, we show that these results are not inconsistent with the di †erence of the SED between them. The inÑuence of the di †erence of SEDs on the highly ionized emission lines is also brieÑy discussed.

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“…Complete Ñux-limited X-ray surveys have found some red quasars or AGNs (Stocke et al 1982 ;Kruper & Canizares 1989 ;Puchnarewicz et al 1996Puchnarewicz et al , 1997. In particular the ROSAT International X-Ray/Optical Survey (RIXOS) survey (Puchnarewicz & Mason 1998) has identiÐed a small sample of red quasars.…”

Section: Introductionmentioning

confidence: 99%

Radio‐quiet Red Quasars

Kim

Elvis

1999

ApJ

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We have performed a successful targeted search for a population of red, radio-quiet, and probably absorbed quasars. Radio-quiet, optically red ROSAT PSPC X-ray sources brighter than 1 ] 10~13 ergs cm~2 s~1 were searched for red (O[E [2.0, O ¹ 20) counterparts in the Automated Plate-measuring Machine catalog of Palomar Sky Survey objects. Of 45 objects for which we obtained adequate followup optical spectroscopy, we have found seven red quasars, Ðve with Their redshifts range a opt \ [2. from 0.06 to 0.31, and their luminosities are moderate, lying on the quasar/Seyfert boundary. These red quasars strengthen the case for a radio-quiet population that is the counterpart of the radio-loud red quasars found by Smith & Spinrad and Webster et al. UnidentiÐed, fainter sources could increase the fraction of red quasars by up to a factor of 7. For the red quasars found here, the Ha/Hb ratios, optical slope, and X-ray colors all indicate that they are absorbed by rather than having intrinsically red A V D 2 spectra. This amount of obscuration seems to hide D1%È7% of quasars at a given observed Ñux or D3%È20% when their Ñuxes are corrected to their intrinsic values. This size of population is consistent with earlier limits, with predicted values from Comastri et al., and is comparable with the rate found among radio-loud quasars. A large population of more heavily absorbed fainter quasars equal (A V \ 5), in size to the blue population could exist without violating existing upper limits, which is in accord with the Comastri et al. predictions.

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Optical and X-ray properties of the RIXOS active galactic nuclei -- I.: The continua

Cited by 30 publications

References 45 publications

ChandraObservations of Red Sloan Digital Sky Survey Quasars

ChandraObservations of Red Sloan Digital Sky Survey Quasars

The Narrow‐Line Region of Seyfert Galaxies: Narrow‐Line Seyfert 1 Galaxies versus Broad‐Line Seyfert 1 Galaxies

Radio‐quiet Red Quasars

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