HELP: XID+, the probabilistic de-blender for Herschel SPIRE maps

Hurley, P.D.; Oliver, S.; Betancourt, M.; Clarke, C.; Cowley, W.I.; Duivenvoorden, S.; Farrah, D.; Griffin, M.; Lacey, C.; Le Floc'h, E.; Papadopoulos, A.; Sargent, M.; Scudder, J.M.; Vaccari, M.; Valtchanov, I.; Wang, L.

doi:10.1093/mnras/stw2375

HELP: XID+, the probabilistic de-blender for Herschel SPIRE maps

Hurley, P.D.; Oliver, S.; Betancourt, M.; Clarke, C.; Cowley, W.I.; Duivenvoorden, S.; Farrah, D.; Griffin, M.; Lacey, C.; Le Floc'h, E.; Papadopoulos, A.; Sargent, M.; Scudder, J.M.; Vaccari, M.; Valtchanov, I.; Wang, L.

Authors

P.D. Hurley

S. Oliver

M. Betancourt

C. Clarke

W.I. Cowley

S. Duivenvoorden

D. Farrah

M. Griffin

Professor Cedric Lacey cedric.lacey@durham.ac.uk
Professor

E. Le Floc'h

A. Papadopoulos

M. Sargent

J.M. Scudder

M. Vaccari

I. Valtchanov

L. Wang

Abstract

We have developed a new prior-based source extraction tool, xid+, to carry out photometry in the Herschel SPIRE (Spectral and Photometric Imaging Receiver) maps at the positions of known sources. xid+ is developed using a probabilistic Bayesian framework that provides a natural framework in which to include prior information, and uses the Bayesian inference tool Stan to obtain the full posterior probability distribution on flux estimates. In this paper, we discuss the details of xid+ and demonstrate the basic capabilities and performance by running it on simulated SPIRE maps resembling the COSMOS field, and comparing to the current prior-based source extraction tool desphot. Not only we show that xid+ performs better on metrics such as flux accuracy and flux uncertainty accuracy, but we also illustrate how obtaining the posterior probability distribution can help overcome some of the issues inherent with maximum-likelihood-based source extraction routines. We run xid+ on the COSMOS SPIRE maps from Herschel Multi-Tiered Extragalactic Survey using a 24-μm catalogue as a positional prior, and a uniform flux prior ranging from 0.01 to 1000 mJy. We show the marginalized SPIRE colour–colour plot and marginalized contribution to the cosmic infrared background at the SPIRE wavelengths. xid+ is a core tool arising from the Herschel Extragalactic Legacy Project (HELP) and we discuss how additional work within HELP providing prior information on fluxes can and will be utilized. The software is available at https://github.com/H-E-L-P/XID_plus. We also provide the data product for COSMOS. We believe this is the first time that the full posterior probability of galaxy photometry has been provided as a data product.

Citation

Hurley, P., Oliver, S., Betancourt, M., Clarke, C., Cowley, W., Duivenvoorden, S., …Wang, L. (2017). HELP: XID+, the probabilistic de-blender for Herschel SPIRE maps. Monthly Notices of the Royal Astronomical Society, 464(1), 885-896. https://doi.org/10.1093/mnras/stw2375

Journal Article Type	Article
Acceptance Date	Sep 16, 2016
Online Publication Date	Sep 16, 2016
Publication Date	Jan 1, 2017
Deposit Date	Feb 27, 2017
Publicly Available Date	Mar 2, 2017
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	464
Issue	1
Pages	885-896
DOI	https://doi.org/10.1093/mnras/stw2375

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.