Skip to main content Accessibility help
×
Home
Hostname: page-component-544b6db54f-kbvt8 Total loading time: 0.539 Render date: 2021-10-22T13:40:25.507Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

Absorption in the ROSAT X-ray Spectra of Quasars

from II - Luminosity Functions and Continuum Energy Distributions

Published online by Cambridge University Press:  04 August 2010

Jonathan McDowell
Affiliation:
Center of Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
Andrew Robinson
Affiliation:
University of Cambridge
Roberto Juan Terlevich
Affiliation:
Royal Greenwich Observatory, Cambridge
Get access

Summary

Abstract

The first ROSAT X-ray spectra of two high-redshift quasars reveal unexpectedly strong absorption when compared with similar luminosity objects at lowredshift. A third quasar shows none. A fourth, low-redshift, radio-loud quasar (3C351) with extended radio structure, shows absorption possibly due to a warm absorber with a strong OVII absorption edge.

Introduction

X-ray spectral observations of quasars have been confined to low redshift objects (z≤0.5) whose proximity makes them bright enough to study and also to those with relatively bright X-ray flux (αox≲1.5). ROSAT, with its high sensitivity, enables us to observe the spectra of high redshift (z>2) and large αox quasars for the first time. We have begun a ROSAT observing program to study the X-ray spectra of quasars selected to cover the full range of continuum properties. In particular this sample includes objects at high redshift, with relatively faint X-ray flux and with a full range of radio properties: strong, weak, extended and compact. We are also carrying out a follow-up observing program to obtain multi-wavelength (infrared – ultra-violet) data for all our ROSAT-observed quasars.

Sampling the full quasar population with ROSAT

To date we have received and analysed data for > 25 quasars. Their spectra are generally steeper than those seen at higher (e.g. Einstein IPC) energies, as observed in general with ROSAT. Our current sample includes 4 high-redshift (z>2.8) quasars with sufficient counts (> 350) to obtain spectral information (Table 1).

Type
Chapter
Information
The Nature of Compact Objects in Active Galactic Nuclei
Proceedings of the 33rd Herstmonceux Conference, held in Cambridge, July 6-22, 1992
, pp. 139 - 142
Publisher: Cambridge University Press
Print publication year: 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Send book to Kindle

To send this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Send book to Dropbox

To send content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Dropbox.

Available formats
×

Send book to Google Drive

To send content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Google Drive.

Available formats
×