1 / 9

The X-ray properties of Spitzer-selected type-2 quasars

The X-ray properties of Spitzer-selected type-2 quasars. Mark Lacy (SSC), Nick Seymour, Anna Sajina, Lisa Storrie-Lombardi, Lee Armus (SSC) Andreea Petric (Columbia), Gabriela Canalizo (Riverside), Susan Ridgway (NOAO), Elinor Gates (Lick Obs). Surveys for dust-obscured AGN.

wayne
Télécharger la présentation

The X-ray properties of Spitzer-selected type-2 quasars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The X-ray properties of Spitzer-selected type-2 quasars Mark Lacy (SSC), Nick Seymour, Anna Sajina, Lisa Storrie-Lombardi, Lee Armus (SSC) Andreea Petric (Columbia), Gabriela Canalizo (Riverside), Susan Ridgway (NOAO), Elinor Gates (Lick Obs)

  2. Surveys for dust-obscured AGN • Chandra surveys vs Spitzer surveys • Spitzer finds objects on basis of hot dust emission. • Finds preferentially high accretion-rate objects (“dirty accretors”). • Chandra misses the most heavily obscured objects, but can find low accretion rate objects that Spitzer misses (e.g. some LINERS/XBONGs/low-luminosity radio galaxies - the “clean” accretors).

  3. Spitzer selection of AGN • Use “wedge” in IRAC color-color plot to select objects with hot dust continua, or require red power-law in mid-IR. • At bright (24mu flux ~5mJy) levels, <z>~0.6, median (bolometric) luminosity about x10 QSO/Seyfert divide. • Optically, our IR-wedge selected AGN sample is 33% normal type-1, 44% type-2, 14% reddened type-1 and 9% low-ionization in the optical (Lacy et al. 2006).

  4. What about the X-ray? • Some of our type-2 quasars overlap 20-50ks XMM pointings. • Most fluxes from 2XMM. • About half the type-2s are detected. • All the detected type-2 objects have high hardness ratios where available.

  5. X-ray survey strategies • Areal density of bright AGN low ~ 6/deg^2 to ~5mJy at 24mu. • Shallow X-ray survey will find the ~1/3 unobscured objects. • Deep pointed observations (~30ks) required for the obscured objects. • Contrast with GOODS-type surveys - finds these objects, but only at z>>1.

  6. ADIOS (Richards et al) • Wide area (~200deg^2) survey in SDSS equatorial field • Field is repeated when northern fields are unavailable • Limit ~25 mag • Applying for Spitzer/IRAC time, principally for quasar survey.

  7. Summary • Making sense of the AGN population requires both Spitzer and Chandra. • Host galaxy absorption/extinction probably plays an important role at the highest columns, but more study of heavily absorbed objects required. • May have to abandon the “pyramid scheme” to study luminous heavily absorbed quasars at z<1 (and other rare objects).

  8. The Compton thick elephant… (with apologies to Banksy (and the elephant))

More Related