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IR STIG Seminar

Infrared Science and Technology Integration Group

DATE

Oct 05, 2021

TIME

1:00 pm EST

COMMUNITY

IR STIG

TYPE

Seminar

Probing Intra-Halo Light with Galaxy Stacking in CIBER Images

Yun-Ting Cheng (Caltech)

We study the stellar halos of 0.2 ≲ z ≲ 0.5 galaxies with stellar masses spanning log(M∗ / M⊙) ∼10.5 to 12 (approximately L∗ galaxies at this redshift) using imaging data from the Cosmic Infrared Background Experiment (CIBER). A previous CIBER fluctuation analysis suggested that intra-halo light (IHL) contributes a significant portion of the near-infrared extragalactic background light (EBL), the integrated emission from all sources throughout cosmic history. In this work, we carry out a stacking analysis with a sample of ∼30,000 Sloan Digital Sky Survey (SDSS) photometric galaxies from CIBER images in two near-infrared bands (1.1 and 1.8 μm) to directly probe the IHL associated with these galaxies. We stack galaxies in five sub-samples split by brightness, and detect an extended galaxy profile, beyond the instrument point spread function (PSF), derived by stacking stars. We jointly fit a model for the inherent galaxy light profile, plus large-scale one- and two-halo clustering to measure the extended galaxy IHL. We detect non-linear one-halo clustering in the 1.8 μm band, at a level consistent with numerical simulations. Our results on the galaxy profile suggest that ∼50% of the total galaxy light budget in our galaxy sample resides in the outskirts of the galaxies at r > 10 kpc. We describe this extended emission as IHL and and are able to study how this fraction evolves with cosmic time. These results are new in the near-infrared wavelength at the L∗ mass scale, and suggest that IHL has a significant contribution to the integrated galactic light, and to the amplitude of large-scale background fluctuations.

Short Bio: Dr. Yun-Ting Cheng received her PhD in Physics from Caltech in June 2021. She works on intensity mapping, large-scale structures, and extragalactic background light. She has studied the intra-halo light with sounding rocket experiment CIBER, and developed theoretical models data analysis techniques for CII line intensity mapping experiment TIME. She is currently a postdoctoral scholar at Caltech Observational Cosmology group.

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An illustration of Sun-like star HD 181327 and its surrounding debris disk. The star is at top right. It is surrounded by a far larger debris disk that forms an incomplete ellpitical path and is cut off at right. There’s a huge cavity between the star and the disk. The debris disk is shown in shades of light gray. Toward the top and left, there are finer, more discrete points in a range of sizes. The disk appears hazier and smokier at the bottom. The star is bright white at center, with a hazy blue region around it. The background of space is black. The label Artist's Concept appears at lower left.