Skip to main content

Research Repository

Advanced Search

SUPER VI. A giant molecular halo around a z∼2 quasar

Cicone, C.; Mainieri, V.; Circosta, C.; Kakkad, D.; Vietri, G.; Perna, M.; Bischetti, M.; Carniani, S.; Cresci, G.; Harrison, C.; Mannucci, F.; Marconi, A.; Piconcelli, E.; Puglisi, A.; Scholtz, J.; Vignali, C.; Zamorani, G.; Zappacosta, L.; Arrigoni Battaia, F.

SUPER VI. A giant molecular halo around a z∼2 quasar Thumbnail


C. Cicone

V. Mainieri

C. Circosta

D. Kakkad

G. Vietri

M. Perna

M. Bischetti

S. Carniani

G. Cresci

C. Harrison

F. Mannucci

A. Marconi

E. Piconcelli

J. Scholtz

C. Vignali

G. Zamorani

L. Zappacosta

F. Arrigoni Battaia


We present the discovery of copious molecular gas in the halo of cid_346, a z = 2.2 quasar studied as part of the SINFONI survey for Unveiling the Physics and Effect of Radiative feedback (SUPER). New Atacama Compact Array (ACA) CO(3−2) observations detect a much higher flux (by a factor of 14 ± 5) than measured on kiloparsec scales (r ≲ 8 kpc) using previous snapshot Atacama Large Millimeter/submillimeter Array data. Such additional CO(3−2) emission traces a structure that extends out to r ∼ 200 kpc in projected size, as inferred through direct imaging and confirmed by an analysis of the uv visibilities. This is the most extended molecular circumgalactic medium (CGM) reservoir that has ever been mapped. It shows complex kinematics, with an overall broad line profile (FWHM = 1000 km s−1) that is skewed towards redshifted velocities up to at least v ∼ 1000 km s−1. Using the optically thin assumption, we estimate a strict lower limit for the total molecular CGM mass observed by ACA of MmolCGM > 1010 M⊙. There is however room for up to MmolCGM ∼ 1.7 × 1012 M⊙, once optically thick CO emission with αCO = 3.6 M⊙ (K km s−1 pc2)−1 and L′CO(3−2)/L′CO(1−0) = 0.5 are assumed. Since cid_346 hosts quasar-driven ionised outflows and since there is no evidence of merging companions or an overdensity, we suggest that outflows may have played a crucial rule in seeding metal-enriched, dense gas on halo scales. However, the origin of such an extended molecular CGM remains unclear.


Cicone, C., Mainieri, V., Circosta, C., Kakkad, D., Vietri, G., Perna, M., …Arrigoni Battaia, F. (2021). SUPER VI. A giant molecular halo around a z∼2 quasar. Astronomy & Astrophysics, 654, Article L8.

Journal Article Type Article
Acceptance Date Sep 2, 2021
Online Publication Date Oct 18, 2021
Publication Date 2021-10
Deposit Date Jan 17, 2022
Publicly Available Date Jan 17, 2022
Journal Astronomy and astrophysics.
Print ISSN 0004-6361
Electronic ISSN 1432-0746
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 654
Article Number L8


Published Journal Article (3.5 Mb)

Copyright Statement
Cicone et al, A&A, vol. 654, L8, 2021, reproduced with permission, © ESO.

You might also like

Downloadable Citations