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Constraints on Dark Matter Scenarios from Measurements of the Galaxy Luminosity Function at High Redshifts P.S

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Constraints on Dark Matter Scenarios from Measurements of the Galaxy Luminosity Function at High Redshifts P.S View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Archive Ouverte en Sciences de l'Information et de la Communication Constraints on dark matter scenarios from measurements of the galaxy luminosity function at high redshifts P.S. Corasaniti, S. Agarwal, D.J.E. Marsh, S. Das To cite this version: P.S. Corasaniti, S. Agarwal, D.J.E. Marsh, S. Das. Constraints on dark matter scenarios from mea- surements of the galaxy luminosity function at high redshifts. Phys.Rev.D, 2017, 95 (8), pp.083512. 10.1103/PhysRevD.95.083512. hal-01555096 HAL Id: hal-01555096 https://hal.archives-ouvertes.fr/hal-01555096 Submitted on 31 Jan 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Constraints on dark matter scenarios from measurements of the galaxy luminosity function at high redshifts P.S. Corasaniti1, S. Agarwal3;2;1, D.J.E. Marsh4, S. Das5 1LUTH, UMR 8102 CNRS, Observatoire de Paris, PSL Research University, Universit´eParis Diderot, 92190 Meudon, France 2African Institute for Mathematical Sciences, 6{8 Melrose Rd, Muizenberg 7945, South Africa 3Stellenbosch University, South Africa 4King's College London, Strand, London, WC2R 2LS, United Kingdom 5Indian Institute of Astrophysics, 560034 Bangalore, India We use state-of-art measurements of the galaxy luminosity function (LF) at z = 6; 7 and 8 to derive constraints on warm dark matter (WDM), late-forming dark matter (LFDM) and ultra-light axion dark matter (ULADM) models alternative to the cold dark matter (CDM) paradigm. To this purpose we have run a suite of high-resolution N-body simulations to accurately characterise the low-mass end of the halo mass function and derive DM model predictions of the high-z luminosity function. In order to convert halo masses into UV-magnitudes we introduce an empirical approach based on halo abundance matching which allows us to model the LF in terms of the amplitude and scatter of the ensemble average star formation rate halo mass relation, hSFR(Mh; z)i, of each DM model. We find that independent of the DM scenario the average SFR at fixed halo mass increases 12 −1 from z = 6 to 8, while the scatter remains constant. At halo mass Mh & 10 M h the average SFR as function of halo mass follows a double power law trend that is common to all models, while differences occur at smaller masses. In particular, we find that models with a suppressed low-mass halo abundance exhibit higher SFR compared to the CDM results. Thus, different DM models predict a different faint-end slope of the LF which causes the goodness-of-fit to vary within each DM scenario for different model parameters. Using deviance statistics we obtain a lower limit on the WDM thermal relic particle mass, mWDM & 1:5 keV at 2σ. In the case of LFDM models, the phase 5 transition redshift parameter is bounded to zt & 8 · 10 at 2σ. We find ULADM best-fit models −22 with axion mass ma & 1:6 · 10 eV to be well within 2σ of the deviance statistics. We remark that measurements at z = 6 slightly favour a flattening of the LF at faint UV-magnitudes. This tends to prefer some of the non-CDM models in our simulation suite, although not at a statistically significant level to distinguish them from CDM. I. INTRODUCTION These measurements have been possible thanks to the detection of very faint high-redshift objects through the gravitational lensing magnification caused by massive In the past few years there has been significant galaxy clusters that are the targets of the Hubble Fron- progress in the characterization of the high-redshift UV- tier Fields (HFF) program [18, 19]. This novel approach luminosity function (LF) (see e.g. [1{9]). Measurements is a promising alternative to deep galaxy survey searches from galaxy samples at z 4 have shown that the slope & such as the Hubble Ultra Deep Field [20{22], but it is of LF remains steep to M 17 magnitudes (see UV not exempt of systematic errors that can bias the deter- e.g. [6, 7]) with important implications∼ − for scenarios of mination of the LF. As an example, the uncertainty in cosmic reionization. Evidence of such steepness persist- the assumed size distribution of very faint galaxies [23] ing to very faint magnitudes (MUV 13) would im- ∼ − and the magnification error due to lens model uncertain- arXiv:1611.05892v3 [astro-ph.CO] 3 Apr 2017 ply the existence of a large population of dim galaxies ties can alter the LF faint-end slope [24]. The latter has contributing to the reionization of the universe (see e.g. been shown to be the dominant source of systematics. In [10{13]). However, it is only very recently that observa- particular the analysis of [24] has indicated that when tions have begun probing the galaxy LF at such low UV- carefully assessed, current LF estimates cannot exclude luminosities. As an example, measurements of the LF to the presence of a flattening of the LF at the faint-end, as M 15 at z 6 and M 17 at z 8 have UV UV expected from a number of numerical simulations studies been obtained≈ − in [14{16],∼ while estimates≈ − to even∼ fainter [69, 70], which would call into question some of the pro- magnitudes have been obtained by Livermore, Finkel- posed reionization scenarios. However, the implications stein and Lotz [17]. The latter have been able to charac- of these measurements are far wider than probing the terise for the first time the LF to M = 12:5 at z 6, UV link between galaxy formation models and cosmic reion- M = 14 at z 7 and M = 15 at−z 8, showing∼ UV UV ization history, since they provide a test of the nature of that the− LF slope∼ remains steep to− very faint∼ magnitudes dark matter (DM) itself. and at high-redshifts. 2 In the standard cosmological model (e.g. [25]), DM small scale distribution of density fluctuations.1 consists of cold, collisionless particles interacting with A common feature of these scenarios is the suppres- visible matter (and indeed other DM particles and neu- sion of matter density fluctuations below a cut-off scale trinos) only via gravity. This is known as the cold dark that depends on the specificity of the DM particle model. matter (CDM) paradigm, and has various motivations Traces of this signature have been tightly constrained us- from particle physics such as supersymmetry, extra di- ing matter power spectrum measurements at z 4 5 mensions, axions, and string theory (for reviews, see e.g. from Lyman-α forest observations (see e.g. [74,∼ 75]).− Refs. [30{32]). In such a scenario the faint galaxies ob- However, it has been pointed out that such bounds may served at high-redshift populate small-mass DM halos. relax if the thermal evolution of the intergalactic medium As an example, analytical models of the LF suggest that is a non-monotonic function of redshift [76]. A detailed galaxies with magnitude M 15 at z 8 should UV discussion of other caveats pertaining the properties of be hosted in halos of mass of ≈ −109 M h−∼1 (see e.g. the intergalactic medium that enter such analyses can [10, 12]). Therefore, the recent≈ measurements of the be found in [51]. Alternatively, DM models predicting a faint-end of the galaxy LF function at z = 6; 7 and 8 cut-off in the matter power spectrum can be constrained probe the lightest and earliest to form DM objects, which using measurements of the abundance of faint galaxies are at the frontier of our knowledge. at high redshifts. This is because the suppression of power at small scale leads to suppressed abundance of low-mass halos. Similarly, constraints on DM scenarios The CDM paradigm has been tremendously successful can be inferred from measurements of the dark matter at reproducing observations of the large-scale distribu- distribution in the local universe. Indeed, it was the tion of matter in the universe [26{29]. In contrast, the discovery of small scale anomalies in the distribution of emergence of anomalies at small scales and the lack of structures surrounding the Milky Way, such as the core- detection of supersymmetric weakly interactive particles vs-cusp problem [52, 53], the missing satellites problem (WIMPs) or QCD axions in the lab (e.g. Refs. [33, 34]) [54, 55] and the too-big-to-fail problem [56, 57] that have have prompted the investigation of broader scenarios prompted the study of non-standard DM models such that evade detection in standard channels. For exam- as WDM. Nevertheless, in the low redshift universe it is ple, direct detection interpretations are altered when the hard to disentangle whether such anomalies are the result DM production method breaks the link between thermal of the non-standard properties of DM or the consequence cross-section and abundance, when production is non- of baryon feedback (see e.g. [58{60]). This is because thermal, or when symmetry dictates particular couplings the amplitude and nature of the baryonic processes that to be absent or suppressed. In the present work we will contribute to the shaping distribution of matter at small be particularly interested in models of DM that not only scales and at late times remains largely uncertain (see evade direct detection, but also differ from CDM in terms e.g.
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