Thermal history of the Universe at intermediate redshift: progress with 21cm absorption measurements

Contribution List

1. An Absorption Feature in the Sky-Averaged Radio Spectrum

Dr Raul Monsalve

6/26/18, 10:00 AM

The EDGES experiment has detected with high S/N an absorption feature in the radio spectrum centered at 78 MHz. This feature is broadly consistent with expectations for the global 21-cm absorption signal from cosmic dawn. However, important aspects of the signal differ from physical predictions. In particular, 1) its absorption amplitude is larger than expected, 2) its profile has surprisingly...

2. Dark matter revealed by the first stars?

Prof. Rennan Barkana

6/26/18, 11:00 AM

The EDGES global 21-cm experiment has detected stronger absorption than expected at cosmic dawn. This absorption can be explained by invoking excess cooling of the cosmic gas induced by an interaction with dark matter. This would have far reaching consequences, including an upper limit on the mass of dark matter particles that conflicts with the expectations for WIMPs. Specific particle...

8. Bounds on Dark Matter annihilations from 21 cm data

Dr Guido D'Amico

6/26/18, 3:30 PM

The observation of an absorption feature in the 21 cm spectrum at redshift z ≈ 17 implies bounds on Dark Matter annihilations for a broad range of masses, given that significant heating of the intergalactic medium would have erased such feature. The resulting bounds on the DM annihilation cross sections are comparable to the strongest ones from all other observables.

4. Speculations on the EDGES 21cm anomaly

Dr Andi Hektor

6/26/18, 4:15 PM

Possible attempts to resolve the EDGES anomaly rely on cooling cosmic hydrogen gas via interactions between dark and visible sector or modifying the soft photon background beyond CMB. The first solution is in tension with cosmological dark matter probes once simple dark sector models are considered. The second solution can be realised as soft photon emission from dark sector. However, the...

11. Constraints on energy injection from 21-cm measurements: primordial black holes, axion-like particles and excited dark matter

Dr Gert Hutsi

6/26/18, 5:00 PM

I will review our recent papers 1803.09697 and 1805.09319

6. 21 cm Cosmology: The status of the current redshifted 21 cm experiments

Dr Saleem Zaroubi

6/27/18, 10:00 AM

In the last decade a large effort has been dedicated to detect one of the last phase transitions in the Universe called the Epoch of Reionization and its preceding epoch know as the Cosmic Dawn, specially with redshifted 21 cm probes. I will review the current status of the various constraints that we currently have on reionization. I will also show the current results from the few redshifted...

7. Probing non-cold dark matter models with the global 21-cm signal

Dr Aurel Schneider

6/27/18, 11:00 AM

The global 21-cm absorption signal induced by the first stars provides unique insights into structure formation at very high redshifts. I will show how the timing of such a signal can be used to obtain unprecedented constraints on the nature of dark matter.

9. Stronger 21cm absorption from charge sequestration

Dr Adam Falkowski

6/27/18, 3:30 PM

The unexpectedly strong 21cm absorption signal detected by the EDGES experiment suggests that the baryonic gas at the end of the dark ages was colder than predicted in the standard scenario. We discuss a mechanism to lower the baryon temperature after recombination. We introduce a stable, negatively-charged particle with a significant cosmological abundance, such that the universe remains...

3. The 21-cm signal and the high redshift IGM

Dr Tejaswi Venumadhav

6/27/18, 4:15 PM

The recent results of the EDGES experiment motivate us to take a closer look at the standard calculation of the 21cm signal. I will give a short introduction to the physics of the 21cm line, and how its brightness temperature depends on the physical conditions in the high redshift IGM, namely the local gas temperature and the flux of Lyman-alpha photons. I will then describe recent work that...

10. 21 cm physics as a probe of (a case for?) dark radiation.

Dr Maxim Pospelov

6/27/18, 5:00 PM

Numerous quanta of soft dark radiation ( e.g. more abundant than CMB photons) could be created in the early Universe by means of various non-thermal processes. The dark radiation
can be resonantly converted to the "normal" photons, creating over-population of Rayleigh-Jeans photons, increasing the contrast of the 21 cm absorption feature. We construct specific classes of models to that...