114 research outputs found
Unveiling the unseen with the Dark Energy Survey: gravitational waves and dark matter
In this thesis I show how large galaxy surveys, in particular the study of the properties of galaxies, can shed light on gravitational wave sources and dark matter. This is achieved using the latest data from the Dark Energy Survey, an on-going 5000 deg2 optical survey. Galaxy properties such as photometric redshifts and stellar masses are derived through spectral energy distribution fitting methods. The results are used to study host galaxies of gravitational wave events and how light traces dark matter in galaxy clusters. Gravita- tional wave (GW) science, and particularly the electromagnetic follow up of these events, is transforming what had never been seen into a new astronomical field able to unveil the nature of cataclysmic events. Identifying the galaxies that host these events, and es- timating their redshift, stellar mass, and star–formation rate, is crucial for cosmological analysis with gravitational waves, for follow up studies and to understand the formation of the binary systems that are thought to produce observable gravitational wave signals. This thesis describes how the host matching is implemented within the DES–GW pipeline and how observations of NGC 4993, the galaxy host of the event GW170817, provide important information about possible formation scenarios for binary neutron stars. In particular, we find that NGC 4993 presents shell structures and we relate their formation to the binary formation. The same galaxy properties are used to derive an observable mass proxy for galaxy clusters. I show that this mass observable correlates well with the total mass of clusters, which is mainly composed of dark matter. It can therefore be used for cosmological studies with galaxy clusters. The measurement of stellar–to–halo mass relations in clusters provides insights on the connection between the star content and the total matter content in clusters, and how this evolves over cosmic time
Standard Siren Cosmology with Gravitational Waves from Binary Black Hole Mergers in Active Galaxy Nuclei
The detection of gravitational waves (GW) with an electromagnetic counterpart
enabled the first Hubble Constant measurement through the standard siren
method. Current constraints suggest that of LIGO/Virgo/KAGRA
(LVK) Binary Black Hole (BBH) mergers occur in Active Galactic Nuclei (AGN)
disks. The claim for a possible association of several BBH mergers with flaring
AGNs suggests that cosmological analyses using BBH and AGNs might be promising.
We explore standard siren analyses through a method that takes into account the
presence of background flaring AGNs, without requiring a unique host galaxy
identification, and apply it to realistic GW simulations. Depending on the
fraction of LVK BBHs that induce flares, we expect to constrain at the
() precision with years or
events ( year or events) of LVK at design (A+) sensitivity,
assuming that systematic BBH follow-up searches are performed. Assuming a more
restrictive prior and that at least of BBHs produces
detectable flares, we may reach a () precision in after 2 (1)
year of LVK at design (A+) sensitivity. We also show that a
precision is possible with complete AGN catalogs and 1 year of LVK run, without
the need of time-critical follow-up observations.Comment: 14 pages, 5 figure
Challenges for Fast Radio Bursts as Multi-Messenger Sources from Binary Neutron Star Mergers
Fast radio bursts (FRBs) are a newly discovered class of radio transients
that emerge from cosmological sources and last for a few milliseconds.
However, their origin remains a highly debated topic in astronomy. Among the
plethora of cataclysmic events proposed as potential progenitors, binary
neutron star (BNS) mergers have risen as compelling candidates for at least
some subset of apparently non-repeating FRBs. However, this connection should
not be drawn solely on the basis of chance coincidence probability. In this
study, we delineate necessary criteria that must be met when considering an
association between FRBs and BNS mergers, focusing on the post-merger ejecta
environment. To underscore the significance of these criteria, we scrutinize
the proposed association between GW190425 and FRB20190425A. Our investigation
meticulously accounts for the challenging condition that the FRB signal must
traverse the dense merger ejecta without significant attenuation to remain
detectable at 400 MHz. Furthermore, we find that if the FRB is indeed linked to
the gravitational wave event, the GW data strongly support a highly off-axis
configuration, with a probability of the BNS merger viewing angle
30) to be 99.99%. Our findings therefore strongly
exclude an on-axis system, which we find, on the other hand, to be required in
order for this FRB to be detectable. Hence, we conclude that GW190425 is not
related to FRB20190425A. We also discuss implications of our results for future
detections of coincident multi-messenger observations of FRBs from BNS remnants
and GW events and argue that BNS merger remnants cannot account for the
formation of > 1% of FRB sources. This observation suggests that short
gamma-ray bursts should not be used to explain global attributes of the FRB
host population.Comment: 9 pages, 4 figures. Submitte
Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82
We present the first weak lensing calibration of , a new galaxy
cluster mass proxy corresponding to the total stellar mass of red and blue
members, in two cluster samples selected from the SDSS Stripe 82 data: 230
redMaPPer clusters at redshift and 136 Voronoi Tessellation
(VT) clusters at . We use the CS82 shear catalog and stack
the clusters in bins to measure a mass-observable power law
relation. For redMaPPer clusters we obtain , . For VT clusters, we find
, and , for a low and a high redshift bin, respectively. Our results are
consistent, internally and with the literature, indicating that our method can
be applied to any cluster finding algorithm. In particular, we recommend that
be used as the mass proxy for VT clusters. Catalogs including
measurements will enable its use in studies of galaxy evolution
in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio
The distant, galaxy cluster environment of the short GRB 161104A at and a comparison to the short GRB host population
We present optical observations of the Swift short-duration gamma-ray burst
(GRB) GRB 161104A and its host galaxy at . We model the
multiband photometry and spectroscopy with the stellar population inference
code Prospector, and explore the posterior using nested sampling. We find that
the mass-weighted age ~Gyr, stellar mass
, metallicity , dust extinction mag, and
the star formation rate ~yr.
These properties, along with a prominent 4000 Angstrom break and optical
absorption lines classify this host as an early-type, quiescent galaxy. Using
Dark Energy Survey galaxy catalogues, we demonstrate that the host of GRB
161104A resides on the outskirts of a galaxy cluster at ,
situated Mpc from the likely brightest cluster galaxy. We also
present new modeling for 20 additional short GRB hosts ( of which
are early-type galaxies), finding population medians of and ~Gyr ( confidence).
We further find that the host of GRB 161104A is more distant, less massive, and
younger than the four other short GRB hosts known to be associated with galaxy
clusters. Cluster short GRBs have faint afterglows, in the lower
() of observed X-ray (optical) luminosities. We place a lower
limit on the fraction of short GRBs in galaxy clusters versus those in the
field of , consistent with the fraction of stellar mass
in galaxy clusters at redshifts .Comment: 20 pages, 9 figures, ApJ: Vol. 904, No.
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