Quick search Find article
Quick search
Find article

New Optical Constraints on the Presence of a Compact Central Object in Cassiopeia A

FREE

Erin Ryan1, R. Mark Wagner2 and Sumner G. Starrfield3

Show affiliations


Deep optical imaging at the location of the pointlike X-ray source at the center of the simeq300 yr old Cassiopeia A supernova remnant discovered in the Chandra first-light observation is presented. R-band images obtained with the Steward Observatory 2.3 m telescope and direct CCD on four nights in 1999 September are used to set a new brightness limit of R gtrsim 26.3 mag (1 σ) on the presence of any optical object associated with the X-ray source. This new limit implies MR gtrsim 10.3 mag and LX(0.2-10 keV)/Lopt gtrsim 800. Accretion models are the most constrained by the optical results. Binary accretion models and scenarios involving very low accretion rates from a disk onto a neutron star or a black hole similar to models for quiescent transient low-mass X-ray binaries are effectively ruled out. Fallback accretion models may be ruled out in some circumstances, but the emitted optical and infrared flux is sensitive to the location of the transition radius, the geometry of the disk, and its inclination to the line of sight.


Subject headings

accretion, accretion disks; black hole physics; stars: neutron; stars: peculiar; supernovae: individual (Cassiopeia A); X-rays: stars


Dates

Issue 2 (2001 February 20)

Received 2000 August 25, accepted for publication 2000 October 18



View by subject




Export








Please login to access our web services, or create an account if you don't yet have one.

You must have cookies enabled in your web browser to be able to login.

Username
Password

Forgotten your password? Get a new one here.