Calibrating photometric redshift measurements with the Multi-channel Imager (MCI) of the China Space Station Telescope (CSST)

The China Space Station Telescope (CSST) photometric survey aims to perform a high spatial resolution (~0.15'') photometric imaging for the targets that cover a large sky area (~17,500 deg^2) and wide wavelength range (from NUV to NIR). It expects to explore the properties of dark matter, dark energy, and other important cosmological and astronomical areas. In this work, we evaluate whether the filter design of the Multi-channel Imager (MCI), one of the five instruments of the CSST, can provide accurate photometric redshift (photo-$z$) measurements with its nine medium-band filters to meet the relevant scientific objectives. We generate the mock data based on the COSMOS photometric redshift catalog with astrophysical and instrumental effects. The application of upper limit information of low signal-to-noise ratio (SNR) data is adopted in the estimation of photo-z. We investigate the dependency of photo-z accuracy on the filter parameters, such as band position and width. We find that the current MCI filter design can achieve good photo-z measurements with accuracy sigma_z~0.017 and outlier fraction f_c~2.2%. It can effectively improve the photo-z measurements of the main CSST survey using the Survey Camera (SC) to an accuracy sigma_z~0.015 and outlier fraction f_c~1.5%. It indicates that the original MCI filters are proper for the photo-z calibration.

The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder – V. Rotational measurements of NGC 891

ABSTRACT The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. In this work, we demonstrate the use of the FF information extracted from three observations of the edge-on spiral galaxy NGC 891 to measure the rotation of N ii and C i gas at far-infrared frequencies in complement to radio observations of the [H i] 21-cm line and the CO(1-0) transition as well as optical measurements of Hα. We find that measurements of both N ii and C i gas follow a similar velocity profile to that of H i and Hα showing a correlation between neutral and ionized regions of the interstellar medium in the disc of NGC 891.

Star formation in luminous LoBAL quasars at 2.0 < z < 2.5

ABSTRACT Low-ionization broad absorption line quasars (LoBALs) mark an important, yet poorly understood, population of quasars showing direct evidence for energetic mass outflows. We outline a sample of 12 luminous (Lbol &gt; 1046 ergs−1) LoBALs at 2.0 &lt; z &lt; 2.5 – a key epoch in both star formation and black hole accretion, which have been imaged as part of a targeted program with the Herschel Spectral and Photometric Imaging REceiver (SPIRE). We present K-band NOTCam spectra for three of these targets, calculating their spectroscopic redshifts, black hole masses, and bolometric luminosities, and increasing the total number of LoBAL targets in our sample with spectral information from five to eight. Based on FIR observations from Herschel SPIRE, we derive prolific star formation rates (SFRs) ranging 740–2380 M⊙ yr−1 for the detected targets, consistent with LoBALs existing in an evolutionary phase associated with starburst activity. Furthermore, an upper limit of &lt;440 M⊙ yr−1 is derived for the non-detections, meaning moderate-to-high SFRs cannot be ruled out, even among the undetected targets. Indeed, we detect an enhancement in both the SFRs and FIR fluxes of LoBALs compared to HiBAL and non-BAL quasars, further supporting the evolutionary LoBAL paradigm. Despite this enhancement in SFR, however, the environments of LoBALs appear entirely consistent with the general galaxy population at 2.0 &lt; z &lt; 2.5.