Impact of CO Emissions on CMB Observations

The cosmic microwave background (CMB) is a faint glow left over from the Big Bang. It contains important information about the early universe, but this information can be disturbed by various sources of noise, including emissions from galaxies outside of our own, specifically from carbon monoxide (CO).

In our study, we look at how CO emission lines from distant galaxies can impact CMB observations made from the ground. We focus on how these emissions contribute to the signals we see in CMB surveys, particularly in observing the CMB at specific radio frequencies.

#Background on CMB Observations

Recent advancements in technology have allowed ground-based CMB surveys to gather data with improved precision. Instruments like the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have begun to map the CMB in great detail. The temperature fluctuations and polarization patterns observed in the CMB can tell us about the structure and evolution of the universe.

As we measure these fluctuations, it is crucial to be aware of any additional signals that could interfere with our observations. One such signal comes from galaxy emissions, especially from molecules like CO, which can emit radiation at the same frequencies we are measuring in the CMB.

#Role of CO in Extragalactic Backgrounds

CO is a molecule that often acts as a marker for star formation in galaxies. As stars form, they often create environments rich in CO, which emits at specific frequencies. These emissions can become a significant foreground signal when searching for the faint CMB.

We investigated how CO emissions, especially from galaxies at various Redshifts (distances in terms of the universe's expansion), might show up in the CMB data collected by ground-based telescopes. These emissions can be detected at specific radio frequencies, which overlap with the frequencies used to observe the CMB.

#Methodology

To study the impact of CO emissions, we used data and models that relate the luminosity of galaxies in the Infrared (how bright they are in infrared light) to their CO emissions. By understanding how these two measures relate, we can estimate how much CO might contribute to the signals observed in CMB surveys.

We focused on specific frequency bands that are commonly used in CMB observations, such as 90 GHz, 150 GHz, and 220 GHz. For these frequencies, we looked at how CO emissions vary with distance (redshift) and how they might correlate with other known signals like the cosmic infrared background (CIB).

#Findings

1. Detectability of CO Emission: Our analysis indicates that CO emissions can have a significant contribution to the signals observed in CMB surveys, especially in the frequency bands mentioned above. At these frequencies, emissions from CO at certain redshifts can be strong enough to be detected in current experiments.

2. Correlation with CIB: We found that the correlation between CO emissions and the CIB is notable. The CIB is a background signal created by numerous distant, dusty galaxies, and its properties are closely related to the CO emissions from these galaxies. This correlation can lead to observable effects in the CMB temperature maps, affecting the overall interpretation of the data.

3. Impact of Uncertainty: We also examined the uncertainties in our models regarding CO luminosity functions, especially the brightest CO emissions. These uncertainties play a crucial role in determining the expected levels of CO contributions to CMB observations. Depending on how accurately we can model these emissions, our predictions can vary significantly.

4. Auto and Cross-Spectra: By creating maps of CO emissions and cross-referencing these with CIB maps, we were able to measure the angular power spectra. This helps us quantify how CO emissions contribute to the overall signals captured in the CMB maps.

5. Future Observations: Our findings suggest that as new CMB experiments come online, such as the Simons Observatory, they will provide an even clearer picture of how CO emissions influence the CMB. This will be important for refining our models and improving the accuracy of our measurements of the CMB and its associated signals.

#Implications for CMB Studies

The contribution of CO emissions highlights the need for careful consideration of foreground signals when interpreting CMB data. As we continue to refine our understanding of the universe's structure and evolution through CMB observations, recognizing and accounting for emissions from CO and other sources will be essential for accurate results.

#Conclusion

Our investigation into the contributions of extragalactic CO emission lines to ground-based CMB observations has revealed significant insights into how these emissions can influence the signals we measure. As we advance our observational techniques and theoretical frameworks, understanding these contributions will be crucial for extracting the most valuable information from the CMB and furthering our knowledge of the universe's early stages and its ongoing evolution.

#Looking Ahead

The future of CMB observations is promising, with new technologies and methodologies being developed. Continued efforts to integrate knowledge about CO emissions and their correlations with other cosmic signals will enhance our ability to understand the universe. The implications of our findings extend not only to astrophysics but also to cosmology, opening doors for new discoveries and insights into the nature of our universe.