Euclid preparation. Far-infrared predictions for Euclid galaxy catalogues: cluster, protocluster, and field

Abstract

The MAMBO mock galaxy catalogue, based on the Millennium Simulation with empirically assigned galaxy properties, provides predictions of FIR fluxes and physical parameters of Euclid-detectable galaxies. Predicted FIR flux distributions confirm that only the brightest Euclid sources will be detectable in existing FIR surveys. We employ stacking to measure the mean dust properties as a function of stellar mass and redshift. We find dust temperatures and infrared luminosities increase with redshift across all mass bins, while dust masses remain roughly constant. FIR number counts from MAMBO show overall good agreement with observations, and the total infrared luminosity function reproduces published estimates across most redshift ranges, extending to z~10. Comparing the Euclid Wide and Deep Surveys, we find that the EDS recovers the total IRLF to fainter luminosities and higher redshifts (up to z~6 in $I_E$), although its detectability falls below 80% at z>4, whereas the EWS becomes strongly incomplete beyond z~2. We also examine the dependence of the IRLF on environment. Schechter fits indicate that the faint-end slope $α$ flattens with redshift for cluster and protocluster galaxies, while remaining approximately constant for field populations. Imposing additional detection limits from Herschel-PACS and SPIRE shows that only the most luminous ($L_{IR}$ > $10^{12.5}$ $L_{\odot}$) galaxies remain detectable at z~4, but the limited MAMBO area (3.14$deg^2$) is inadequate for statistically robust (>3$σ$) constraints. Survey areas at least 30 times larger are required. Overall, the MAMBO FIR extension reproduces key number count and IRLF trends, provides realistic predictions for FIR-detected Euclid galaxies, and highlights the importance of synergies with current and future FIR/sub-mm facilities to probe environmental dependence with sufficient depth and area.

Figures (17)

• Figure 1: Predicted flux ranges of EWS-detectable MAMBO galaxies in various FIR/mm bands and redshift bins. Markers show the mean flux. The bands per subplot are offset in the x-axis for clarity.
• Figure 2: Average FIR physical properties of EWS-detectable galaxies as predicted by MAMBO. Top: Average dust temperatures ($T_{\text{dust}}$). Middle: Average dust masses ($M_{\text{dust}}$). Bottom: Average IR luminosities ($L_{\text{IR}}$).
• Figure 3: Differential number counts of the MAMBO mock for the Spitzer-MIPS bands. Data and models from the following works are shown for comparison: Lagache_2004, Dole_2004, Papovich_2004, Frayer_2006, Frayer_2009, Shupe_2008, Berta_2010, Clements_2011, Bethermin_2010_spitzer, and Magnelli_2013.
• Figure 4: Differential number counts of the MAMBO mock for the Herschel-PACS bands. The legend in the $100\,\micron$ panel also applies to the $160\,\micron$ panel, and vice versa. Data and models from the following works are shown for comparison: Lagache_2004, Frayer_2006, Berta_2010, Clements_2011, Bethermin_2010_BLAST, and Magnelli_2013.
• Figure 5: Differential number counts of the MAMBO mock for the Herschel-SPIRE bands. The legend in the $250\, \micron$ and $350\, \micron$ panels apply to all three panels. Data and models from the following works are shown for comparison: Lagache_2004, Frayer_2006, Berta_2010, Clements_2011, Bethermin_2010_BLAST, and Magnelli_2013.